METHODS AND SYSTEMS FOR DETECTING AND RESOLVI G FAILURE EVENTS WHE RAISI G A D LOWERING A FAVLOAD

CROSS REFERENCE- TO RELATED APPLICATIO

0005 § Tliis app lication claiaas priority to U,S, PaiSBt: Application, Ηό. 15/389,338 filed: Becember 22, 2ΘΙ6 and U.S. Fm^sk Application ^" No _* $ί3$$$$9 filed oft September ¾. ^' 2(M-6 _? bolts of which are herein iBeorporatcd by reference m their eBtirety,

well as on land. Other examples are also possible. SUMMARY

}0¾0S| Example implementations ^' tmy relate to various error detection and correction tec ni ues when picking » and towering a payload coupled to a. tether of a hic s stem arranged on an tmmantted. aeri al vehicle (UAV). For exam le, the winch system may include a -motor for winding, and. eawiading the tether from a spool, and the UAV's control system may control the motor to lower the tether and monitor and analyze an electric curren supplied to the motor in order t deiermitie whether a payioad has detached from me tether. T his process may be repeated up to a predstemiined number of femes, at which point the control system, may operate the motor to detach the tether f om the spool, le ding both: the tether and the pay load behind In another exam le, when lilting a payload, the control system ma monitor and analyze the moto current: i order to■determine thai the tether or payload is snagged. The control system may responsiveiy operate' the motor to lower and then rest me lifting the payload and/or to detach the tether from the spool, leaving both the tether and the payload behind. In yet. another example _* when picking up a pa load _* the control system may monitor and analyze the motor current in order to determine whether the payload has been attached to the tether. Responsive to determinin at least, a threshold snnther of times that the payloa has failed to attach to the tether, the control system may operate the motor to retract the tether and c&Kse the UAV to abandon, piete of the payload. O¾06l 1» one aspect _s a system is provided. The system: includes a tether disposed on a spool, "where a first end of the tether is tion-fixedl wound on the spool, and a payload coupling apparatus stroet ired to mechauicaly couple a second end of the tether to a payload. The system further includes a motor arra ged tft a UAV, where operatin the motor in a first- mode arid a second, mode respectively counters and assists unwinding of the tether due to gravity. Additionally, the system includes a control system configured to operate the motor according to a -delivery mode. During operation In the delivery mode, the control system is eonfigirred to operate the motor to unwind the tether and lower the payload toward the ground, detect when the payload contacts the rouijd, and responsiveiy initiate a tether overrun process to attempt to .release the payload from the payload cou lin apparatus, where the tether o ver-run: process is repeatable up * to a predetermined nttmher of times when the payload does not release from the payload coupling apparatus. The control system is further configured to, dfcttag operarioti to. the delivery mode, determine that the over-ru process has been repeated the predetermined number of times without successful release of the payload, responsiveiy operate me motor to allow me tethe to unwind during ascent of A UAV, and cause the UAV to initiate a flight to a different location, such that die flight of die UAV unwinds■the tether imi separates th first end of the tether from the spool, thereby -releasing the tetter from: the UAV-.

}Θ007| In another aspect another system is ps-ovided. The system me hides- a tether disposed on a spool, where a first end of the tether is nou-feediy wound on the spool, and a payioad coupling apparatus structured to mechanicall couple a second end of the tether to a payioad. The -system further includes a motor arrange*! is a A-V, where operating the motor in a lirst mode and a second mode respectively -counters and assists unwinding of die -tether dye to gravity.. Additionally, the system rochides a control system configured to control . the motor to carry out tethered delivery of the payioad. During the process of delivering the payioa to a target location and. while the II AV is in flight, the corstFol system is configured to determine that both {a) an unwound length of the tether is greater Ittan a threshold length and (hi a motor current of the motor is greater than a threshold current for at least a predetermined timeout period. Responsive to making such a. determination,, t e control system is former -configured to Operate- the mot r to allow the tether to unwind when -die ti W ascends and cause the tJAV to initiate ¾ flight to a different location, such that the fight of the UAY nnwinds. the tether and separates the first end of the tether from the spool, thereby releasing the tether from the UAV,

(-0988] 1» yet another aspect, anothe system is provided. The system Includes a tether disposed on a spool and motor arranged In a OAY _>; where operstki the m t r in a first mode and a second mod respect! vely counters and assists unwindin of the tether due to gravity.. The system ftirther includes a payioad coupling apparatus stni teed. to mechanically couple the tether to a payioad and control system configured -to control: the .motor to carry oat tethered delivery of the payioad, .During process of picking up the payioad to be delivered and while the WAV Is. over or near t a pickup location, the control system is -configured to, responsive to a deterannatlau that the payioad couplin apparatus is mechanically coupled to the payioad, operate the motor to retract the tether and lift the payioad toward the UAV. The control system is further configured to, while retracting the tether with the payioad coupled thereto, detect: an. error condition when both: (a) the unwound lengt of tether is greater than a threshold length and (h) a motor etuxent of the motor is greater than a threshold current, make an attempt to correct the error condition by operatin the motor to unwind the: tether, and then resume retracting the tether. Further the cont ol system is configured to dete mi e that a predetennmed ^' number of attempts to correet the error condition have been made without successfully correcting the error condition, and respossfvely end the process of picking up the pay ioad and initiate a payioad delivery process to r tu the pay load, to the grunrtd at or near the pickup location.

}θ¾ 9| 1B yet another aspect, another systern is provided. The system includes a disposed on a spool aid. a motor arrange in a HA Y, where erat on the motor in a first mode and a second mode respcehveiy counters and assists UBwinding of the tether due to ra ity- The system former includes a payioad coupling apparatus structured to mechaaiea!ly couple the tether to a payioad and a control system configured to control ihe motor to carry out tethered delivery of the payioad,. .Dur¾g a process of picking up the payioad to he delivered, and while t e- t AV is over or near to a pickup location _* the control system is configured t operate the motor to nnwiftd die tether and lower the payioad coupling apparatus to a payioad aiiaetaent altitude. The eoaito! system, is !wfiter eoriigured to, after lowering the tether and waiting for a predeterBBBed payioad attaehmeBt period, perform, an attachmeBt verification process that includes (a) operating the moto ^' in the first mode for a predetermine attachment 'verification period, and (h) determining, based at least hi part on a motor current during the predetermined attachment verification period, whether or not the payioad. coupling apparatus is mechanically coupled to the payioad, where the control system, can l wer die payioad coupMBg apparatus: and repeat die atfaehrnetit verrfseation proces up to a pr determined number of times when it is detertnlrsed that the payioad coupling apparatu is Hot mechanically coupled to the payioad. Further, the control system is configured to determine thai die attachrnetrt verification process has been repeated the predelermined number of times ithout successful coupling of the payioad coupling- apparatus to the payioad- and responsiveiy initiate process to cancel picfesp of the payioad and initiate flight of the OAV to a di iereni locatiori.

f061ij 1B yet anothe aspect, aaother system is provided. The system may include means for operating a motor arranged in a UAV according to a delivery mode. The system, m also include means for, while operating m the delivery mode, operating the motor to unwind a tether and lower a payioad toward the groaml, detecting when me payioad coBtaets the gron , and respoirsiveiy initiating a tether over-run process to attempt t release the payioad. .from, a payioad coupling apparatus, w ¾-e the tether over-rnn process is repeatabie u to a predetermined niimher of times when the payioad doe not .release from the payioad ^' coupling apparatus. The system may further include means tor, during operation in the d.eiiver mode, determining that the over-run. process has been repeated the predetermined mrmber of times without successful release of the payioad, responsive y operating the motor to allow the tethe to laiwiad dnring ascent of die IM-V, and causing the VI AY to initiate s flight to a different location, such that me light of the OAV unwinds the tether and separates die first end of the tether froitt the spool, {here y mfeasing the tether from the UAV,

[O&IXf _. IB yet another aspect, anothe system Is piovided. The system tsay include means for controlling a motor arranged its a UAV to carry out tethered delivery of ^* a payioad:. The system may further include means for, d-ariftg die process of delivering the payload to a target location and while the UAV is hi flight, determining that both (a): an unw und length ■of the tether is greater than a threshold length and (b) a motor current of the motor is greater than a threshold curren for at least a predetermined tnrieont period.. The system may also include means for, responsive to making such _, a tomninafion. operating the motor to allow tire tether to. un ind vvhen fee OAV ascends and cansisg the AY to initiate a flight to a different location, snch ilmt the ight of the UAV unwinds die tether and separates the first end of the tether fr m the spool, thereby releasing the tether from the UAV..

(00121 in yet another aspect, another system is provided. The system may include means for controlling a motor arranged in a UAV to cany out tetltered delivery of a. pa load. The system ma further include means for, during a process of picking up tiie payload to fee delivered and. white the UAV is over or nea to a pickup location, determining that a payload. coupling apparatus is mechanically coupled to the payload and tesponsively operating tie motor to retract a tether arid lift the payload toward the UAV. The system ma also include means for _* while retracting die tether -with die payload coupled thereto, detecting an error condition when both; (a) the un otnid: length of tether is greater than a threshold length and (¥} a motor current of the rnoto is greater than a threshold current, making an attempt to correct the error condition by operatin the moto to unwind the tether, and then resumin retracting the tether. Further, the system may include mean for determining that: a predetermined number of attempts to correct the error condition have been made without successfully correcting the error condition, and responsively ending the process of picking up the payload and initiating a payload delivery process to return the payload to the ground at or near the pickup location.

j0ul3f in yet another aspect, another system is provided. The system ma include meatis for controll ing a motor arranged in a U AV to carr out: tethered delivery of a payload. The system may further include mean for, during a process of pickin up the payload to be delivered, and while the UAV is over or near to a . pickup location, operating tire motor to unwind a tether and lower a payload couplin apparatus to a payload attacimient altitude,. The system ma also Include means for, after lowering the tether and waiting for a predetermined payioad. attachment period, performing an attachment verification process that includes (a) operating the motor- in. a mode that counters unwinding of the tether dire to

Mill? i)ESC.' F i0 OF THE D AW S

{ ^' O iSf Figure 1A is a simplified illustration of M «rmaimed aerial veoicie., according to art example embodiroeat .

|θΐϊΙ6 Fig re I is a simplified iUustration of an aaraanned aerial e icle _s according to aa exampl e erohijdimeat.

| ^' M17| Fig tire 1€ is a siraplified illustrat ion of an ttamanried aer al vehicle, according to m example eaibodiment

10 181 Figaro ID is a simplified iilusttation. of an mma ne aerial vehicle, according

^■ to■ an exam le embodiment,

Jflii lf 1 Figure j E is a simplified illustration of an unmanned aerial ve cle, according to an exarripl e erobodirneat .

|O#20] Figisre: 3 is. a siriiphfied bloeh diagram iltastraiiag components of aa itnnmaaed aerial vehicle, aceorrfiag to m example embodiment

f §0211 FigBfe 3 is a simplified block diagram ilhsstratrsg a IIA system, acc rd n to aa example embodiment,

{0022J Figures 4A, 4B, and 4G show a payload delivery apparatus, aecordta to ■example embodiments. j0023j Figure: 5A sfeo s- a perspective view of a payload delivery apparatus 500

Including pay load 510, according to an example efl¾odii»erii>

0024| Figure SB ts a cross-sectional sste view of payload delivery apparatus 509: and payload 510 sto¾¾ i Figure 5A,

}M2S| Figure SC is side view of pay bad deli very apparatus 500 and pa loafi 510 shown in Figures 5A and SB.

|0<i2S| Figure 6 A is a perspective vie of payload coupling apparatus BOO, according to an example effibodimeRt

i002?f Figure 6B is a side view of payioad coupling apparatus 800 shown in Figure

6A.

|M28j Figur 6C. is a front view of payload cotiptmg apparatus 800 shown in Figures

OA and SB.

|Μ2θ| Figure 7 is a. perspective view of payioad coupling apparatus 8 0 shown in

Figures- 6A~6€, prior to iase ^ou into a payload eouplipg apparatus receptacle positioned the fuselage of a UAV.

(.0039)- Figur 8 is anothe perspective view of payioad coupling apparatus 8 0 shown, ia Figures 6A-6C, prior to insertion into a payioad coupling apparatus: receptaeie positioned I» the i½«iage of a UAV.

|0¾3I| Figure 9 shows, a perspective view of a recessed restraint slot and payload coupling apparatus receptacle positioned its a fuselage of a U V>

932| Figure HiA shows a side view of a payload delivery apparatus 500 with a handle 50 of payload 51.0 secured within a payioad coupling apparatus 800 as the payload. 51.0 moves downwardly prior to touching down for delivery.

f 0O33;f Figure 10B shows a side vie of payload delivery apparatu 500 after payioad 510 has landed on the ground showing payload: coupling apparatus 800 .decoupled from handle 51 1 of payload 10.

j¾$34| Figure 10C shows a side vie of payload deliver apparatus 500 wit payload coupling apparatus 800 moviug: aw¾y :troni toarsdie S i 1 of payioad 510.

|Q03S| Figure 1 1 is a side view of handle 51 1 of payload 51 ik

{0036} Figure 1.2. shows a pair oflocfcing piss.570, 572 extending through holes 14 and 516 in handle 51 1 of payload 510 fo secure the handle 11 and to of payload 10 within the fuselage of ^' UAV,

f§037|: Figure 13-A is a perspective view of payioad coupling apparatus tOO prior to haviag a haadle-oif af&yload .pos iipaed wlthi i: slot ¾0 of payload coupling apparatus 900. f003SJ Figure 13S is a perspective view of payioad coupling apparatus 900 after ddiverirsg a payioad a»d decoupling f¾:r» a handle of a payioad,

|0 39| Figure 1.4A is a front perspective view of payioad coupling apparatus 9fK> shown in Figures L3A. arsd 13B, according to an example embodiment,

}O 0| Figure J B- is a rear perspective view of payioad couplin apparatus 9:00 shown in Figure HA.

{0041 } Figure ! 4C is a side view of payioad coupling apparatus 900 showu in Figures

14A arid J4B..

(0042] Figure 14X3 is frost view of pay oad couplrug apparatus .900 sitown iti

.Figures 14A-I4C>

|iW43{ Figure 14E is a to view of payioad coupling apparatus 900 shown in Figures

14A-D.

|1H44| Figare Γ5Α is a perspective view of pay load coiipiitrg apparatus 1001), according to an exasnpie emi>odin®it,

|0045{ Figure 15B is aHOiher perspective view of payioad. eottpHug apparatus .1.000 shown in Figur ) 5 A.

0046j Figure ISC is a side view of payioad couplin apparatus 1000 show is

Figures ISA aad 15B.

0¾4?1 Figure 15D is a top view of payioad couplin ap aratus 1000 shown M

Figures j.5A~€.

j0048J Figure 15B is eross-sectiona! side view of payioad couplin apparatus .1000 shown in Figures ISA-F .

Θ0491 Figure- 1.6A is a side view of payioad coupling apparatus 800 ^* w t a slot 808 positioned above lip 806', according to an examp!c embodiment.

f0050| Figure !6 is a side view of ^' payioad coupling apparatus £00' after slot 808. has been closed followin decoapling of payioad coupling apparatus 800 ' f ont a -handle of a payioad.

fOOSl f Figure 16C is a bross-seeuoual side view of payioad. e uplmg; apparatus 800 ^* shown in Figure 16A.

J0652J Figure WD is a eross-seetional side vie of payioad. coupling apparai«s 800 ^s shows in. Figure 16B.

f 00531 Figure 1? is a flow chart of a method for carrying oat temered picku of a payioad fo strbseipertt delivery to alarget .ioeaiioa _s according to art example embodiment. f0054 Figure-: 18 is a t¾ chart of a method for cany sa out tethered d very of- a pay oad, according, o an example etahodimeffi.

j{ ^| f>5S| Figure 19 is an exatnple ilo ehaii for facilitating control of die tether for pnrposes of interacting with and/or providing feed ack t a user, according to an example embodiment

|9f «6| Figure 21) i!instrates a motor current, le el ^' over tirne, _: according to an example erAodimerit.

fOOSTJ Fignre 21 illustrates a detected current spike that is ffidkative of a particular nset-isienictioa with a tether, accord iug to air example enibodimeui

|00S8| Figure: 22 il!ristrates a. motor response based- an die particular aser-iRteraciioB, according to an example embodimeBt.

Figure 23 illustrates a motor response process to a just tension of die ie&er, according to an example embodiment.

Fig re 24 illustrates a motor response process to provide the feel of a detent, according to an example em odiinsen

Figtue 25 iliusitaics a motor response process followed by : OA V response process, -according to an example embodiment

l&MZl Figure 26 Is a flow chart of a- met od for deteTOiniug whedier a payJoad has detached ffoM a tether o a tlA , according to an example embodiment.

¾OJ Figure 2? is an -exampl flowchart for initiating a damping routine to da en oscillations of a payioad .-coupimg- apparatus, according to a»* example mbo iment.

00 4 Figures 28 A to 28D collectively illustrate initiation of a dampittg routine during a tether retractio process, according to an example embodimen

|006S Figure 29 is. an example flowchart for initiating forward flight to dampen osciilatioos of a payload, according to an example embodiment.

f M<¾i Figures 38A. to 30D collectively illustrate use of orwa d flight to dampen oscillations of a pay load, according to an example embodiment

fiKI&¾ Figure 31 is an example -flowchart for reducing an extent of flight stabilization to dampen osc llations of payioad, according to an example embodiment, |θί 8| Figure 32A to 32H collectively illustrate use of reduction in the extent of fii glrt stabili ado to dampen oscillations of a payioad, according to an example embodiment jCK Jf Figure 33 is an cxampie flowchart for selecting one or more damping routines to help dampen oscillations of a payioad, according to an example embodiment. [0078} Figure 34 is a flow cksi of a method fo detachiftg a tether fioitt a UAV, according fo an ex mple efliboditnerit

,[b 7l Figure 33 is a flow eliari of a mei-hod for deteotifig and addressing dmwrwar forces o a tether when lowering a payload toward ike groundj according to an example erftbodiraest.

|00?2| Figaro 36 ¼ a low chart of a method for detecting and addressing downward feces on a tether hen ioeking a payload toward, a l AY, according t an example embodiment.

{ 07¾ Figure 37 is a So : etort of a etri.od ior detecting whether a UAV s swecesstiii!y pis-ked, u a pay!e-ad, according to a« exan^Ie smbodiraeni.

f§i?4J Figures 38A illustrates a poriorr of a state diagram of OAV carrying oat a jMyload pickup arid deli very process,, according to an. example effitedimerrt,

fM75j Figrsre 38B iSltsStrates another portiors of the state diagram of a. UA¥ carr ii¾

^• out. a payioai pickup and delivery' rocess _.* according to att example embodimeiit

0 761 Fi re 38€ ilkrstrates another ort on of the state diagram of a UA V carrying out a payioad pickup and elivery process, according to an example embodiment.

pt?8f The present embodiments are related to die use of ^" unmanned, aerial vehicles

(iJAVs) or unmanned aerial systems (iJASs) (referred to collectivel herein as tJAYs) that are used to carry a payload to be delivered or retrieved. As examples, OA Vs may b used to deliver or .rcttieve a payload to or -from an individual or business. In operation the payload to be delivered is secured to ike OAV and the IIAV is then flown to the desired delivery site. Ones the tJAV arrives at ¾e delivery s te, the UAV my land to deliver the payload, or operate in a hover mode and lowe the pay toad front ke UAV towards ilie delivery site a&hi$ a tether and a wiaek meeka sm positioned will i tke UAV tJpoa iouchdowu of the payload, a payload. coupling apparatus,, sometimes referred to as a "capsule," is automatically decoupled from the payload. In addition, the payload may be retrieved wftiie the OAV is operating in a hover mode by posttkiniag a ndle of the payload into a slot in die payload ■coupling apparatus.

J007«¾ i« order to deliver the payload, the UAV may include wi «s mechanisms to secure the payload: during transport an release the payload upon delivery. Example e bodiments may take the fern of or otherwise relate to an apparatus for passively coupling a payload. to a U AV for transport sad releasing the payload u o dehvery.

0086j Such a payload coupling apparatus .may include a housing couple to the UAV by a tether ihat may he wouad. and unwonnd to raise and lower the lionsing with respect to the UAV, The faousing ma Include- one or more swin arms adapted to extend from, he housing at aa acnte angle, forming a hook on whiek the payload may be attached. When the housing and attached payload re lowered from tfee UAV (e,§, _:> by unwinding the tether) to 8 traasport location below the OA (eg., ihe gfound), tie payload may detach, torn, the hook. f0 8t| For instance, once t e payloa reaches the grouad, the UAV m y over-ruft the tether by eontinaituj to unwind the tether. As the ay ad retaaius stationary oa the groand, the payload couptiag apparatus aiay coauuue to lower, arid a gravitatfeiml asd or asi ineffiai force on the housing. May cause the swing arm book to detach front the payload. Upon detaching front the payload. the swing arm ntay he adapted to retract into the housing,, and the payload coupling apparatus may aseead (e.g., _: by i¾txactiag the tether) toward the UAV, leaving the payload on the ground.: As the payload coupling apparatus approaches the l!AV _; a device adapted to receive the ^' housi g _: roay engage a eanr of the swing arm causing the s iug arn to extend from die housing at au ae-nte angle, thereby ί¾¾ηίη a hook for securing another payload for delivery by the UAV.

j0eS2 More specifically* the present enihodirnents advantageousl include a unique payload coupling a par tus.. In one embodiment, the payload coupling apparatus includes a slot downwardly exteading front an oater surface of the payload coapling apparatus towards a center of the payload coupling apparatus. The slot is adapted to receive a handle- of a. payload, and supports the payload during delivery or retrieval of the payload _* Once the payload .reaches the ground, the payload coupling: apparatus eoniittues to ntove downwardl until th handle of the payload is decoupled, tern the slot of ^* the payload coupling ap r aiS: A» outer surface of a lower lip beneath the slot is undercut such ihat ¾ extend less than- the outer surface of the upper eud of die payload c upling device above the- slot to prevent the payload coupling device ff at reengaging With the handle of the payload during retrieval of the payload coupling device to the UA.V _; . or ith catching on power lines or ree braaches. | 083| The _: payload couplin apparatus may include earns positioned on opposite sides of an. outer surface thereo As the payload. coupling apparatus is winched hack to the UAV, the caras of the payload coupling apparatus are adapted to -engage with correspoadiag cants■ within the fuselage of the UAV such ihat when the caras engage, the payload coupling apparatus is able to rotate to orient the payload coupling apparatus in desired position within the fuselage of the UAV.

fih?S In this, regard, the payload may have a longitudinally extendin top such that when the earns on the outer surface of the p load coupling apparatu engage the mating cants wiihis the fesekge of the UAV, the longitudinally extending top is rotated into a desired position within a corresponding loagliudinaUy e tending recessed restraiat slot in the bottora of the fuselage of the UAV, in other embodanerits, the payload ma he simpl draws int s tight positioning against the bottom of tire fuselage of the UAV. In such cases, the top of the payload is not r p ired to have a loagiiadinaHy extending top thai heeoates positioned within a cavity ta t e fuselage when the cams- of he payioad coupling apparatu are in -©ttgagemeiit wit tnatiag earns w¾ » the fuselage. However, where earns are used, the caaas- of the payioad couplin apparatus and the mating earns within a payioa eoopiltig receptacle is the fuselage may property restate the pay bad coupling apparatus to orien t the payioad hi a desired position with respect to the _: fuselage,

|θβ8$! A significant .advantage of the payioad coupling apparatus is that the payioad coupling apparatus includes mo moving p ts, thereby reducing its complexity and reducing the possibility of part faitare which exists when moving parts are involved in a pyload coupling apparatus,

| 086 ihe payioad may advantageously include a. handle thai is well-suited for positioning within the slot of the payioad coupling apparatus, tile handle may constructed of a thin, flexible plastic .material having a high degree of fiejiihiiity allowing for eas ^' insertion into fee slot of he payioad coupling mechanism, and ls for easy decoupling: from, the slot of the payioad coupling mechanise upon landing; of the payioad, ^' Handle flexibility is desirable to allow the pay ad and payioad coupling apparatus to bang vertically straight as the handle bends to matc the angle of fee slot in the payioad coapling apparatus, A more rig d handle m kes it easier for the jsayload ^' coupling apparatus to decouple fto iSte handle upon package landing, although it fee handle ^' is too flexible the pay ioad coupling apparatus could flip over and not release. Furthermore, it is desirable that upon decoupling, the haiidie should spring back to a vertical orientation whieh further reduces the r booking of the handle with the slot of the payioad coupling apparatus, and to pull the package tight into the restraint when engaging within the fuselage of the UAV . It should, also be noted: that the handle could also be out of paper or other natural fiber, with or without plastic lamination or piastio gS ass/natural fibers for extra strength. As an example, fiber feinfbreed paper niay he used as well

The handle rnay also advantageously include ^' a pair of holes that are adapted to receive locking pins positioned within the UAV, The: lockin pins may have a, conical shape to facilitate insertion o the holes in the handle and to pull the package int tiglii engagement Within the recessed restraint slot in the fuselage of the OAY, Onee the cants of the payioad coupling apparatus are engaged with, the mating earns within the fuselage, the handle is positioned in the desired : orientation, A servo motor, or other mechanism such as a regular eleetric motor with a !eadscrew, or rack and pinion wit limit switches to control travel (or other mechanism such as a linear actuator) may he wsed to move the conical locking pins tlitough the holes in the handle to hold the handle and payioad beneath tightly in ^• pdsifioa, allowing for high speed fligh t of the ti Α ? when the payload is secured beneath the UAV. Alternatively, tbe locking ^' pirn or pin could e moved into position■ within a recess or opening to the payload coupling apparatus itself, rafter than into holes ί» the handle of the .of the package id secure the payload coupling apparatus and package to the IIAV,

|OT88| The pay load may take the for of an aerodynamic tote, although the payload may have any «ura¾er of dlfcrent configurations and geometries. However, where a linear recessed restraint slot is positioned with the tuseiagc. it is desirable ihai the top of the payioad has a generally linear shape to it within the linear recessed restraint slot within, the foselage.

[00891. The pay!ead coupling mechanism ma have different configurat ons as well For example, a tether may be attached to a bottom of the payloail coupling apparatus, and is posiiioaed within a vertically e ten ing tether slot is the payload coupling apparatus. The vertical tether slot exten s through; the payload coupliKg apparauis that is adapted to receive a handle of a pay load, in this position, the handle of the payload is positioned within the slot storing delivery and retrieval. The payload coupling apparatus also includes a pair of upwardly extending fingers positioned about ike slot wit an opening between th pair of lagers.

$ 0f When the payload touches the ground, the psyload coupling apparatus continwes to move downwardly an autoinarioaliy Is decoupled te» the baud So of the payload. The pa loail coiipllag apparatus nia foelade a top half that is weighted, sach that upon decoupling from the handle of the payioad, the payload coupling apparatus iips over and rotates 1:80 degrees such that the pair of upwa dly extending ingers are rotated 180 and extend: downwardly. During this rotation, the tether ecomes disengaged from the vertical tether slot and moves through the opening between the pair of fingers. As a result, the payload coupling is prevented from, reengaging with the handle of the payload because the slots extends downwardly. In addition, the downwardly extending slot after release of the handle also helps to prevent the payload coupling apparatus from engaging with power lines or tree branches as it is winched back to the UAV, because the opening in the slot extends downwardly. Alternately, the payload coupling apparatus ma be bottom weighted,

[0091 ] This embodiment of the payload coupling apparatus may also include cams on an outer surface thereof adapted to engage Blaring cams within a payload coupling apparatu receptacle within the insetage to orient the payload coMpliing apparatus in a desired position wi thin the tlsselage of the UAV.

|θΐϊ92| in another emtjodipienl a vertical slot may be positioned ^■■ within the pay ba coupling apparatus adapted to receive a handle of a payload and to support the handle and

911 degree orientation,, in this regard, helical ea n surfaces may .meet at an a ex on one side of the payioad coupling raec aaism, and helical earn surfaces may meet at a rounded apes on the oilier side of the payioad. coupling ineenautsm. The hook is speeiieally designed so that the package .hangs in .the eenterBae of the hook, enabling alignment in both directions from 90 degrees.

|Θ094| Besides the alignment functionality, the payioad hook also releases tile package passively and automatically wfeea the package touches the ground upon delivery.. This is accomplished through -the shape and angle of the hook slot and the corresponding handle on the package. The hook slides off Ihe handle easily when the payioad foueltes down due to the mass of the capsule and also the ujeriia wasting to continue moving the capsule downward, past the package. The end of the hook is designed to be recessed slightly from the body of the capsule, which, prevents the hook from accidentally re-aiiaehing to the handle. Afler successful release, the hook gets win.eiied back np int the aircraft All this functionality (package alignment during ^' pickup and passive release during delivery) may advantageously be achieved without any moving parts in this hook embodiment (referred to as a, solid state design). This greatly increases reliability and redness eost. The simple esi n, also makes user interaction very clear self-explanatory, la addition,: the payioad coupling ap ratus may b& bottom eighted si? "that It ^' remains m a desired vertical orientation, and does flat tilt.

j0 95f The package used for the inc ap/pick op operation may be an aerodynamiea!Iy shaped tote with a reinforced snap-is handle (e.g. m de out of plastic or other niaterials .such as fiber), although other shaped pa teads may also be used. The handle of the payioad attaches the payioad to the hook of a payioad. coupling apparatus and its slot or opening Is shaped to allow for a reliable passive release. The handle also may inc ude two smaller openings for Soeklag pius, _: . The rem&rcerueat of the handle is beaefteial to transmit die torqtie from the capsule into the package during the alignment rotation. The package itself itiay be made out of ca dstock mi have an internal, tear strip. The this fiber ta e tear strip may tan along the pe i Meier of one package sid and. enables the extstomer to open the package easily after delivery,

fiMJ¾»J Whea the payload is■winched up and alignment, is completed, the payioad is piilled into a recessed it iraint. slot in the fuselage f the OAV _» using the additional vertical tray el of the capsule in its receptacle . The rece ssed restraint slot matches se shape of the upper portion of the payload and stabilises it during cruise flight, preventing any excess side to side or back and forth sway rnotioa. The recessed res nt. slot is also completely recessed into the fuselage an has ho protruding parts, allowing for good aetodytiinftlc oft the return flight (after the package has been delivered).

f 0€#7| The present eatbodlroeuts provide a highly Integrated winch-based pickup and delivery system for UAVs. A number, of significant advantages ma be provided. For example, the ability to pick up ai& deliver packages without the need for landing is provided. Tile system i able to winch up a package with the aircraft hovering. There also may he no seed for iniTastractare at the merchant or customer in certain applications. The advantages Include high, mission flexibility and the potential for limited, or in¾astrueture- installation costs, as well as iticreased flexibility iu payload geometry.

II. Illustrative Unmanne Vehicles

$98f Herein, the: terms "unmanned aerial vehicle'' and 'TiA.V ^5' ' refer to any

■aat£8i©HJO¾s or semi-autonomous vehicle that is capable of performin sotne functions without a physically present human pilot.

J ^y f>99{ A iJAV can ^' take yarions forms. For example, a JAV may take the form of a fixed-wing aircraft, a gilder aircra.it, a tail-sitter aircraft, a jet aircraft, a dneted fan aircraft, a lighter-than~air dirigible such as a biiinp or steerahle balloon,; a rotorcraft such as a heiicopicf or multico tet, and/or an oMlthopter, atnon other possibilities. Further, the terms "dione,"

UAV 1110a is descending to a delivery location., or ascending following a delivery, in the example UA I 1 0a, stabilizers 1108 are -shows attached to the rotor supports 1.1.1 .

f OlOtSJ During flight,, the UAV l!QOa may control the direction and/or speed of its movement by controlling its pitch, roil, yaw, and/bf attitude. For example, the stabilizers 1 108 may ine!ude one or more rudders: 1108a for controlling the UA V's yaw,, and the wings 1102 may include one or mom elevators for controlling the U AV 's pitch and/or one or more ailerons 3 102a for controlling the UAV's roll. A another example, increasing or decreasin the speed of all the propellers simultaneonsiy can result in the UAV 1 100a increasing or deereasing Its altitude, respectively.

&i f Similarly, Figure B shows another example of a fixed- wing U ^' A V 1,20. The fixed-wing UAV 120 includes a mselage 122.. two wings 12 with an airfbil-shaped cross section: to provide lift for the UAV 120, a ertical stabilizer 126 (or fin) to stabilize the plane's yaw (to s left or ^' right), a horizontal stabilizer 128 (also referred to as an elevator or iailplane) to stabilize p tch (tilt up or down), iaftding gear 130, aftd a proptdsiorr unit 132, which can include a motor, shaft, arid propeller.

}0165| Figure iC shows m example of a UAV 140 with a propelle in a pusher configuraiioa. The i&rm "pusher" refers to the feci that a propulsion unit 142 is mounted at the hack of the UAV and "poshes" the vehicle fo ward, m contrast to the propulsion «nit being mounted at the ftimi o jhe UA¥, Similar to the description provided for Figures |.A and IB. igure iC depicts eon ufcRi structures used .¾· a pusher plane, including a fuselage i 44, two wings 146, vertical stabilizes l48,.arsd the propulsion unit 142,. hich can. include a motor, shaft, ami propeller.

010 1 Figure ID shows an example of a tai l -si iter UA 160. In the illustrated esa iple, the taiFsitter UAV 160 has fixed wings 162 to provide lift and allow the UAV 160 to glide orizaatally (fcg., along the x-axis, in a. position that is approximately perpendicular to the position shown m Figure IB). ffcw ve¾ the fixed wings 1.62 also allow the tail-si tef U AV 160 to take off and land vertically on its owu.

Θ1Θ7| For example, at a launch, she, the taiFsitter UAV 160 .may he positioned vertically (as. shown) with its tins 164 and/or wi^ 162 ^' resting on the gr¾w:rid and stabilizing the UA 1-60 la the vertical position. The tail-sitter UAV 160 m y then- take off by operating lis piopellers 166 to generate m upward tewst (e.g , a thrsst tliaf is generally along the y- axis). CJeee at a. sattable .altitude, _, the fail-sitter OAV 160 may use its Haps 168 t reorien itself in a horizontal position, such that its fuselage 170 is closer to beifig aligned, with th - axis than the y~axis. Positioned ^' horizontally, the propellers: 166 may provide forward thrust so that the tail-si iter UAV 3,60 can fry in a similar manner as a typical airplane.

ffli§8 Many variations m the illustrated foed-wing UAVs are possible., For iasfanee, feed-wing UAVs may include mo e or fewer propellers, and or rnay utilize a ducted fan or mr tipie ducted fans tor propulsion.:. Further, UAVs wit more wmgs (e,g,, as ¾-wing ^* ' configuration wiin foirr wiags), with &w¾r wings, or even with no wings, are also possible.

|O109| As noted above, setae- embodiments may involve other types of UAVs, in. addition to or ia flic alternative to fixed:-wing rjA.Vs, For Instance, Figure IE shows an example of a rotorcraft that is- connnonly referred to as a muliieopter 1 0:. The mnlticoprer 180 :raay also be referred to as a quadcopier, as it includes fou rotors 1.82, It should he uaderstood thai xam le embodiments may involve: a rotorcraft witlr more or fewer rotors than the u capier 180. For e&mtjfi a helicopter typically s two rotors. Other examples with .three or more rotors are possible as well Herein, t e- ^' tefcm ¾ttlticopte ^! refers to any rotorcfaft having store i m two rotors, an the term "lielicopter'' refers to rotoreraft Slaving two rotors,

}0110| Referring to th multicopie 180 in greater detail, the four rotors 182 provide propulsion and maneiiverabilily for th multicopter I SO. More specifically, each rotor 182 includes blades thai are attached to a motor 184. Configured as such, the rotors 182 may allow the mohieopte SO to take off and: land vertically, to jnaneuver in any direction:, and/or to hover. Further, the pitch of the Males may be adjusted as a group and/or differentially, and may allow tfte multleopter 180 to _. control its pitch, roll yaw, and/or altitude.

f!H I t I it should fee understood that references herein to an "rmrBasi ed" aerial vehicle or UAV can .apply equally to .autonomous and semi-autonomous aerial vehicles. In. as autonomous inipleittent&tioft, all functionality of the aerial vehicle is automated;; e.g., pre- rogrammed or controlled via real-time corupiiter ftmciiorialiiy that responds to input from ^■ various sensors and/or pre-determihed iriforisation, hi a semi-autoriomous impiemejitation, some functions of au aerial vehieie may be coatroiied by a ir man operator, while other functioBS are carried out autorjouiousiy. Fiather, in some emhodirrjests, a UAV may be configured to allow a remote operator to take o ver tactions that can othcRvlse he controlled autonomously by the UAV. Yet further, a gives type of fuReriou ma be con trolled- remotely at one level of abstrac tion and perfbraied aiiioaomously at another level of abstiaetiott. For ex m le, a remote operator could contr l high level navigation -decisions for UAV, such as by specifying that the UAV should travel from one location to another (e.g., .from warehouse iii a suburban area to delivery address in a nearby ciiy), while the UAV's navigation system autOBornousIy controls mo e fine-graiaed navigation decisions, such as the specific route to take between the two locations, specific fight controls to achieve the route and avoid obstacles while navigating the route,, and so on.

fQillJ More generally, it should be understood that the exafnpte UAVs described herein are mt intended to be hayting. Example embodirtieiits may relate to, be implemented within, or take the fmrn of any type of tmrnattued aerial vehieie.

HI, I iistradve UAV Cotnpeaente

{ttlUJ Figure 2 is a simplified block diagram illustrating coraponents of a UAV 200, according to an example embodiment, UAV 200 ma take the form of, or be similar In form to, orse of the UAVs 100, 120, .1.40, MO, aa ISO described m reference to Figures 1 A- IE. However, UAV 200 may also take other forms. some e bodiments,, a tlAV may include a tow-power, digital 3-axis magnetometer, which can be used id realize an orientation independent electronic cotrtpass for accurate heading information... However, oilier types of magnetometers may be utilized as Well Other examples are also possible. Farther, Bot that a TJAV could include some or all of the bove- deseribed inertia sensors as separate components from as IMU,

|ΘΊ20| UAV 200 may also iacfcde a pressure sensor or barometer, which can be usee! to determine the altitude of the UAV ^' 200. Alternatively, other sensors, .such as sonic altimeters or radar altimeters, can be used to provide an indication of altitude which may help to improve the aecttracy of and/or prevent drift of an IMO,

l&tM l a Sirftier aspect, U AV 200 ma ineliide one or more sensors that allow tie

UAV to sense objects In the environment. For instance, in the illustrated emlwdiment, UAV 200 includes ultrasonic sensor(s) 204. Ultrasonic sensor(s) 204 can. determine u¾e distance to ati object by generating, sound waves and determining the time interval between transmission o the wave and receiving; he correspondm echo off an object. A typical application of an ultrasonic sensor for unmanned veMeies or IMUs is low^evel altitude control and obstacle: avoidance. An ultrasonic sensor can also be used for vehieks that need to hover at a certain hei ght o need to be capable of detec ting obstacles. Other systems ean he used to determine, sense the resence- of _* and/or de&oriiae the distance to aearby objects, such as a. light detection and tarjging ( DA t) system, laser detection and ranging (LADAR) system, and/or an infrared or forward-fooidn inirated (FOR) system, among other possibilities,

jfj Ϊ 22| In some e bo&inients, tJAV 200 :wtay. also include one. or more imaging system(s):. For example, one or more still and/or video cameras may be utilked ^' by IJAV :20ft to ea tnre image data from the IIAV's environment. A a specific example, eharge _^ eoupied device (GCD) cameras or complementary nietalOxide-semieondttctor (CMOS) cameras can be used with unman ed ^' vehicles. Such imaging sensor(s) have .anmerous possible applications, such, as obstacle avoidance, localization tec ni es, ground tracking for more accurate navigation Ce,g., by applying optical So techniques to images), video feedback, asid.¾r image recognition: and processing,. among other possibiMties.

|0.I23 IJAV :20ft m also include a GPS receiver 206. The GPS receiver 206 ma be configured, to provide data that is typical of well-known G:PS systems, such as the GPS Coordinates -.of the UAV 200, Such GPS data may he utilized by the UAV 200 for various fonctioBs, s sack the U V a use its GPS receiver 206 to help navigate to tire caller's location, as indicated., at least in part., by the GPS coordinates provided by their mobile device. Otltcr examples are als possible .

use localization to update its ma of the envifoniBertt This feontmnoas mapping process ma be referred to as simultaneous localization and mapping (SLAM). Other navigation techniques may also be ntili¾ed.

f ^§ $26J Its some embodiments, the negation module 214 ma navigate ^'■ -using tec uique that relies on waypoints. In particular, waypOhits are sets of coordinates that identify points in physical space. For instance, as ah -Bavigatiou. aypoi«t may he defined b a certain, latitude, ioRgiiude, and afhtude. AeoordiBgly, navigation: module 214 ma cause UAV 200 to move from waypoint to wayp int., in order to ultimately travel to final destinatioB. (e.g., a final waypoatin a sequence of waypoints).

ffli27{ in a .further- as ect, the navigation -module 214 and/or other -component, and systems of the UAV 200 may be configured for ' ocali^on' ^* to more precisel navigate to the scene of a target location. More specifically, it ma be desirable is certain situations for a UAV to be -withi - a threshold distance of the target location where a payload 2 8 is being delivered by a UAV (e,g., within a lew feet of die target destination). To this end, a UAV may use a two-tiered approach in which it rises a more-general iocation-determisiatrOB technique to navigate to a general area that is associated with the target location, and t en use a more-refined location-dete∞iinatioB technique to Identif m& navigate to the target location within, the general area. f :12S For example, the UAV 200 rosy navigate to. the genera! are of a target desiinatios where a ayload 22S is Mag delivered using waypoi s arid/or map-based navigation. The UAV ia&f then swf teh to a mode in which it utilizes a ieeaSiz&tioa process to locale aftd iravei to a more specific location. For instance,, if the tlAV 260 is to deliver a pa load to a user's home, th OAV 200 may need to be substantially- close to the target location is order to avoid delivery of the pay!oad to nadesired areas (e.g.,. onto a roof,, into a pool, onto a neighbors property,, etc.). How ver, a GPS signal may only get the IJAY 200 so far es-g^ wthm a. block of the user's borne). A more precise tocatiOE-deterniiiiaiton technique ma then be used to &cl the specific target location,

10129! ^" V¾rio«s types of !ocsticsri-deierP««aii.0« techniques sMy fee used to accomplish localization of the target delivery location osce the OkV 200 has navigated to the general area of the target deliver location. For isistasiee, the IJAV 200 may be equipped with one or rnore sensory systems; such as, for example, ultrasonic sensors 204, krfrared sensors hot. sh witj _s and/or other sensors, which. «m ' provide input that the navigation nioehi!e 21 utilizes to navigate autonomously or sen-¾i-antoriom.o«siy to the speeifie target ideation.

ίθ ΐ3θ| As another example, once the. UAV 200 reaches the eaerai area of the target delivery location (or of a moving; subject such as a person or their mobile device), di IJAV 200 rria switch to a "Oy^by-wire" mode here it is controlled, at least in part _* , by a remote operator, ho ca» navigate the O V 290 to the specific target tocatitoa. To ibis ead, sensory data fro the OAV 200 may be- sent to the renieie operator to assist them, is aavigating the tJAV 200 t the specific location.

{QtM} As yet ano her xample, the UAV 2§0 may include a module that is able to signal to a passer-by for assistance in either reaching the speeifie target delivery location; for example, the UAV 200 m y display a visual message reqnestlag such assistance in. a .graphic display, pl y an audio message or torse through speakers to indicate the need for s»ch assistance:, among other possibilities, Site a visual or aisdio message might indicate that assistaaee is needed Is deUvering the U AV 200 to a particular person or a: particular location, ati ight provide inforrnatson to assist the passes-by m delivering the OA 200 to the person o location (e.g., a description or picture of the person, or location, slid; or the person or location's name), among other possibilities. Such a feature can be tisefel in a scesiario in which the DAY is unable to use sensory fisHeiiofi or -another location-deienninafioa ieehniqiie to reach the speeifie target location ^' . However, this fe ture is ttai limited to sucli scenarios: ίθ132 lift ^' s me embodiments, once the UAV 200 arrive at the gcjief l area of a target deli ers iocatieo* tft ^' UAV 201 ⁾ ni&y utilize a beacon fern a user's remote device the user ¾ mobile ohotse) to locate the person, Siich a beacon may take variorts fbtths. As as example, consider tile scenario where a remote device, such as the m b le phone of a pefsoii who requested a UAV -delivery.,. is able to _: send out directional signals (e.g., via an F signal, a light signal and/or an audio signal). In this scenario, ^' the ¾AV 200 may be configured to navigate b "soiirchig' ^* such directional signals ~ m other words, by determining: where the signal is strongest and M H¾at iig aceordingiy . As another example, a- m bile device cart emit a ntx e ey, either |n the human range or outside the human range, and the UA 200 can listen for that fre uenc aud navigate accordingly.. As a related example, if the UAV 200 is listening for spoken commands, then the UAV 200 could utilize spoken, statements, such as ' ia over here!" to source the specific location of ihe person requesting delivery of a payioad.

03f 33 In an alternative arrangement, a navigation module may be implemented at a remote computing device,, which eommnnieates wirelessly with the OA V 200, The remote cftmptttittg device may reeeive data indieattoji tie operational state of the UAV 200, sensor •data. frota the UAV 200 that allows it to assess the environmental conditions feein experienced fey the UAV .300, and/or location iiiforniaiion for the UAV 200. Provided with siseh mfermation,. the remote computing device may determine aliiiudinal and or directional adjustments that should be made by the UAV 200 and/or may determine how the UAV 200 should adjust its mechanicai feature (e.g., its rwdderfs), elevatoris), ai ^: lei¾n(s}, ao:0¾r the speed of its propel !.er s)) hi orde to ef& tnate such movements. The remote computing system may then communicate such adjustments to the UAY 200 so it can move its ihe determined manner.

C. CoaittiBiiicatioi! Systems

f0 4f hi a furthe aspect, the UA 200 includes one. or more commuriicatioa systems 18. The coumiunieaii ii systems 218 may include one or m t wifeless interfaces aiid'bv one or more wireline - interfaces., which allow he- ^' II AV 260 to eonimtoicate via one or more networks. Such wireless . interfaces ma provide fo c jmmunicatio under one or more wireless eommnrncation protocols, such as Bluetooth, WiFl (e.g,, an. IEEE 802.11 protocoi), Long-Term Evolution (LTE , iMAX (e.g., atUBEE- 802,16 standard), a radio-freqnenc ID (ΙίΗ ) protocol, aea reld eommumeation (NFC¾ m ot. other wireless connn«nic3tion protocols. Such wireline interfaces may inelnd as Ethernet hiterlaee, a Universal Serial Bus (USB) interface j or similar interface to co tmisleate via a wire, a twisted pair of wires, a

otherwise access.

D. Fewer Systewts

[#.t37| In a tiuther aspect _* the UA 200 may -include power systom(s) 230:, The power system 220 may include one or more batieries for providing power to the UAV 200, hi one example, the one or more batteries may be rechargeable and each battery may fee recharged via a wired connection between the battery and a power supply and/or via a wireless charging system, such as an inductive charging s stem that applies an external, time- vary tn niagneite field to an internal battery.

E _* Payload Delivery

fOORJ The UAV 200 may em lo various systems and configurations order to transport and deliver a pay load 2:28. hi some inmlemen.t&uons, the payload 228 of a given UAV 200 may include or take the fwm of a ''package" designed to transport various goods to a target delivery location. For example, the UAV 2()Q can include a compartment, in which an item or item may be transported. Such a package may one or more food stents, purchased ^' goods, medical items,, or any other objeehs} having a size and weight suitable to be fsiispo fe between two locations by the UAV, In other embodiments, a payload 22S may simply fee the one or more items that are feeing delivered (e,g,, without any paelage honsing the items).. {01391 ϊύ some embo iment^ the payload 228 may be attached to the UAV sod located substantially outside of the UAV during- sotae or all of a flight by the UAV. For example, -the package tmy be tethered or otherwise releasahiy attached belo the UAV during Sight to a target location. Is as embodiment where a package carries goods below the UAV,.. the package may include various features thai protect its contents from the envnomnent reduce aerodynamic drag on the system, and pr vent the contents of -the package from shifting daring UAV flight

J0I.40| Far instance, when;: the payload 22 takes the form of a package for tra&sportm items, the package may include an outer shell constructed of water-resistant cardboard, plastic, ©r arty other Hghtwdght sod water-resistaiit material Further;, in order to reduce drag, the package may feat tire siBooth surfaces With a p inted front that reduces the frontal cross-sectional area. Further, the sides of the package may taper front a wide bottom to a -narrow top, iiieh allows the package to. serve as a narro pylon that reduces interference ¹ effects on the wiug(s) of the U A V, This may move some of the frontal area and volume of the package away from the wingis) of the UAV, thereby preventing the reduction of lift on the wlngCs} canse by the package. Yet farther, in some embodanentk,, the outer shell of the package ma be constructed (torn a single sheet of material in order to reduce air gaps or extra m terial, both of which tmy increase drag on the system,: Additionally or alternatively,, the package niay Include a stabilizer to dampe package Slitter. This reduction in flutter tmy allow the package to: ha ve a less rigid connection to the UAV and may cause the contents of the package to shift less during flight.

{01411 in oxdef to deli er the payload, the UAV tmy include a winch system. .221 controlled b the tether control module 216 in order to lower the payload 228 to the ground white the UAV hovers above. As: shown in Figure 2, the winch system >22.1 may include tether 224, and the tether 224 may be coupled to the payload 28 by a payload coup-Bag app aratus 226. Use tether 224 may he wound on a spool that is coupled to motor 222 o f the UAV, The motor 222 ma take the form of a DC motor (e.g,, a s&vo motor) that can he actively controlled by a speed controller. The tether control module 216 can control the speed controller to cause the motor 222 to rotate the spool, thereby tmwhiding or refracting; the tether 224 and lowering or raising the payload couplin apparatus 226. In practice, the speed controller may output a desired operating rate (e.g., a desired RP ) for the spool, ^• which may correspond t the speed at which the tether 224 and payload 228 shonld be lowered towards ike ground. The motor 222 ma then rotate fte spool so- that it nmiuta s the desired operating rate. ttta vary the aaiotaa b which it adjusts the speed (e.g., the RPM) of the s ool, aad tins may ^• vary- the deployment tare of the tether 224, Other examples are also possible.

10145} IK some embodiments, the tether eontroi module 216 ma be configure to iitmt the moto current supplied to the motor 222 to a ma imum: value. With such a liaiii placed OR die m&iffl cttn¾at _> there may be situatioas where the motor 222 cannot operate at the desired operate specified: by the speed controller. For instance, as discussed in more detail below, fere may be -situations where the speed controller specifies a desired operatin rate at which the motor. 222 should retract the tether 224 to ard the UAV 200, but the motor carrept may he limited such that a large enough wnwar force on the tether 224 would coahieraet the retractiog tbrce of ti motor 22 and cause the tether 224 to unwind Ib-stea , And a further discussed below, a limit on the motor current ma he iaiposed and or altered depending, on aa operational state of the UAV 200.

| ^' 0I 6 ΪΒ some embodintents, the tetiser control module 216 may be configured to deteraime a states of the tether 22.4 m m the payload 228 based on the amou t of current supplied to the motor 222. For instance, if a downward forte is applied to the tether 224 (e.g. , if the pay taad 228 is attached to the tether 22 or if the tetber 224 gets snagged ©a. as object when ret aedng toward the UA 200), the tether eontroi module 2 may aeed to increase- the motor entreat in order to cause the determined rotational speed: of the motor- 222 arid/or spool to match tbe desired speed, Similarly, when the downward force is removed from the tether 224 (fcg., wpou delivery of the payload 2 8 o reraovst of a tether snag), the tether control modiste 2.16 ma need t decrease the. motor current m order t eaiise the determined rotatioftal speed of the motor 222 and/or spool io match the desired speed.. As such, the tetbe control module 16 may he configured to moaitor the eurrest supplied to the motor 222. For instance, the tether control a¾od«le 216 could determine the motor current based o sensor data received from a current sensor of the motor or a current sensor o the power system 220. In any ease, based on the current supphed to the tnoior 222, determine if the payload 228 is attached to the tether 2 , if someone or something is pnlling on the tether 224, an /or if the payload coupling apparatus 226 is pressing against the (JAV 2 0 after retracting the te her 224. Other example are possible as well.

101.47} Daring delivery of the payload 228, the payload coupling apparatus 226 can be co»8gttre4 to seeare the payload 228 while being lowered from the XJAV by the tether 224, and can be further eoufigared to .release, the payload 228 upon teaching ground level _* The payload coupling apparatus 226 can then be .retracted to he UAV by reeling in the tetber 224 asing the motor 222.

.housing n ay reduce the likelihood of the release mechariisrn snagging the payioad 228 or other nearby objects when raising the release rnecharsism toward ihe -UAV νρύ delivery of the payload 228.

{0149J Active payload. release Mechanisms are also possible. For example, sensor such as barometrie pressure based altimeter and/or aceeierorneters may help to detect the position of the release meehaihsnj (and the payload) relative to the ground Data ironr the sensors cas be communicated: back to the UAV and/or a control system oye a wireless link aar! used to hel in determining when the release mechanism has reached grorisd level (e,g. % detecting a measurement with the aeceleromeier that is characteristic of gmnad: impact), in other examples, the UAV may determine that the payioad has reached, the ground based on a weight sensor detecting a threshold low downward force on the temer and/or based on a fereshold low measurement of power drawn by the winch when lowering the pay load.

ϊ ^' β!5 | Other systems and techniques for delivering a pay load, n addition or in the alternative to tethered delivery system are -also possible. For example, a UAV 200 eoeid include an air >ag drop system or a paraeh«t drop system. Alternatively, a: OAV 20Q carrying a payioad eoaid simply land on. the groan.d at a deliver location. Other examples are also possible.

W+- Ilhistrsiive UAV Bepfey;me»i Systems

{0151J UA V systems may be implemeated In order to provide various JAV-relaied services. I particular, 1J AVs ma be provided at a matiber of different lawnch sites that may he in: comnrimication with regional: sn#%r central control systems,. Suc a distributed UA.V system may allow UAVs to he uiekly deployed to provide services across a large geographic

operation of a U AV are also possible,

|0i5S| In an illustrative emhodinteut, the UAV 384- .may take various forms- For example, each of the UAVs 304 aia be a UAV such as those illustrated ia Figures .1 A- I E. However, UAV system 300 may als utilize other types of UAVs without departing -from the scope of the invention. Irs some i?nplementati.ons _½ all of the UAVs 304 may be f the same or a similar cGn%inatioa. However, in other implementations, the U AVs 304 may include: number of different types of UAVs. For ^" instance, the UAVs 304 aiay include a number of t es of UAVs, with each type of UA V bein configured tor a diflereut iypc or types of payload delivery capabilities,

Θ15«| The UAV system 300 may further include a "remote device 306, which may take various forms. Generally, the reuiote device 306 may he any device throug which a direct or indirect equest to dispateh a UAV can be made, (Mole that n indirect request may voive an mm McM a. thai t e resposded to by dispatching a UAV, such as Tequestiiig package delivery), ¾ an example embodiment, the remote device 306· ros be a mohije _: phone, tablet computer, lapto computer, personal cotttptiier, or my network- cormeeted CQistj utfeg device. Further, in some mstartees, the remote device 306 may riot be a computing device. As an example, a standard telephone, winch allows for co utatio via plain: old telephone service (POTS), may serve as the remote device 306, Other types of remot devices are also possible.

91571 Further, the remote device 306 ma be eopigared to eommirfiicate with access system- W2 via one or more types of eom tinieatkro ner or¾s) 30¾, Fo example, the remote device 306 may eemmunieate with the access system 302 lor a human operator of the acces system 302) by communicating over a POTS network, a cellular network, and/or a data network such as the internet, Other types of networks may also be utihaed.

plSSf in some embodiinents _* tile em te device 306 ma he configured io allow a. user to request delivery of one of more: items to desired location. For exarnple:, a user could request AV delivery of a ackage to their home via their mobile phone, tablet, or laptop. As another example, user could request dynamic delivery to wherever they are located at the time el* delivery. To provide such dynamic delivery, the UA system 300 may receive location ½formation (e.g. _s GPS coordinates, etc.) feom the user' mobile phone, or any other device on the nse 's person, suets {feat a UAV ca navigate to the user's location {as indicated by their rtiobtle phone),

[ftl.S¾ In an illustrative arrangement _s the central dispatch ystem 310 may be a server or group of servers, which is configured t receive dispatch messages .requests arid or dispatch instructions from the access system 302, Such dispatch messages may request or Instruct the central dispatch system 310 t coordinate the deployment of llAVs to various target locations. The central dispatch system: 310 may he further configured t ro tte suck requests or instructions to one or more local dispatch systems 312, To provide such mnctionahty, the central dispatch system 310 may communicate with the access system 302 vi a data network, such as the internet or a private network that is establishe tor communications between access systems and automated dispatch systems,

fOlft f the illustrated eonlguration,, the central dispatch system 310 may be configured to coordinate the dispatch of OAVs 304 irofti a number of different local dispatc s tems 312. As such, the ceutial dispatch system 310 may kee track of which IJAVs 30 are located at which local dispatch systems 312, which liAVs 304 are entreutty available for complex system, and/ ^' or redistributed among the cental dispatch system. 310, the local dispatch s tem(s) 312, the access system 302, asd or ike deployment sysfeai(s} 314 ai various ways.

10165 j Yet tether, while each local dispatch system 312 is shown, as having two. associated deployaiersi systems 314, a given local dispatch system 312 may alternatively have more or fewer associated deplo ment systems 314. Similarly, whil the central dispatch system 310 is shown as being in communieatiQs with two ^: local dispatch systems 312, the central dispatch, system 310 may alternatively he ia communication with more or fewer local dispatch systems 12.

|0ί66 In a fotther aspect, the. deployment systems 314 m take varioits forms, In general, me deployment systems 14 roay take the form of or include, systems for physically launching one or more of the UAVs 304, Such latmch systems may include features that provide for s automated UAV launc and or features that allow for Inunan-assisted IJ AV iaunek Further die deploymcat systems 314 may each be configured to launch one particular OAV 304, or to launch .multiple UA ^' Vs 304.

JM ?J The deployment systems 31 aa y further be configured: to provide additional functions, including; for example,, diagnostic-related function such as verifying system, fpnerionaiity of the IJAV, verifying i¾ctroeai¾y of devices that are housed within a OAV (e.g., a paylead delivery apparatus), and/or maintaining devices or other items that are housed ia. the llAV (e.g., by monitoring a status of payioad such as its temperaiwre, weight, etc,),. |θίδ8| in some embodiments, the deployment systems 314 and their correspondin

UAVs 304 (and possibly associated local dispatc system 12) may he strategically distributed throughout an area such, as a eity. For example _* , the deployment -systems 314 may be strategically distribpted such that each deplo meni system 314 is proximate. to one or more payioad pickup locations {e.g., near a restaurant, store, or warehouse),. However, the deployment systems 314 (and possibly the local dispatch systems 312): may be distributed, in other way s, depending upon the particular iraplea»¾Miop. As an additional example, kiosks thai allow users to transport packages: via UAVs: may he installed ia various locations. Such kiosks may include OAV launch systems, and may allow a use? to provide their package for loading onto a UAY and pay for UAV shipping services, amo¾g other possibilities. Other examples are also possible,

f(il69§ hi a l¾rtl¾f aspect, the UAV system 300 may include or have access to a user- aecoiini database 316. The pser-aceonnt database 316 ma include -data for a mimber of aser accounts, aad which are each associated with one -or more person. For a given user account. ^• fiie user ^account: data ase 316 ma include data related to or useful in pro viding U AV ^« reiaied services. Typically, the user data associated w¾ eae use account is optionally provided by an associated user mdfot Is collected wi h the associated: user's permission.

0l?0 Further, in some embodiments, a person .may be required to register for a user account with the iJAV system 300, if they wish to be provided with UAV-related. services by the UAVs 3 J4 from OAV system 300. As suck, the usef-accoue database 31 may include mithorization ¾f madou. for a gives user account (e,g., a m mme- and password}, and/or Gtk inforrnadon t at may be used; to . autho ze access tit a user account.

jOI 71J hi some enibodiroeais, _; a person ma associate one or mote of thei devices with their user aceowet, such that they can aecess the services of U V systetK 300. For example, when a person uses as associated mobile phone, e.g., to place a call io operator of the access .system 302 or sen a message requesting a UAV-related service to a dispatch system, the phone may be identified via a■ unique device identifieatiori number, and the call or message may thm be attributed, to the associated user account. Other exarnples ate also possible.

V, S2xairt|jfc Sy n aad Ap arat«s fm Payload Delivery

|0.l¾f Figures 4A, 4B, and 4C sh o w a UAV 00 that Includes a payload delkery system 410 (could also be referred to as a. payload delivery apparatus),, according to as example embodiment As shown, payload delivery syste 410 for UA 400 includes a tether 402 coupled to a spool 0 , a payload latch 406, and a payload 1 coupled to the tether 402 via a. payload eoupim apparatus 412. he payloa iateh 406 can f¾nciion to alternately sec tire payload 408 and release the payload 408 upon delivery. For instance, as shown, the payload latch 406 may take the form of one or more pins that can engage the payload coupling apparatus 412 (eg,,; by sliding into one or rnore rece ag slots ia the payload coupling apparatus 412). Inserting the ins of the payload. latch 406 Into the payload coupling apparatus 412 may secure the payload coupliag apparatus 412 within a .receptacle 414 oa the underside of the U V 400, thereby preveating the payload 408 rrotn befeig lowered from the UAV 0Q. in some erhhodimersts, the payload latch 40S may be arranged to engage the spool 404 or the payload 40S rather than the payload coupling apparatus 412 s» order to prevent the payload 408 from lowering. Is other emhodhaeats, the OA 400 may not include the payload latch. 406, nd the payload delivery apparatus triay be coupled directly to the UAV 401 ⁾ ,

173f hi some embodiments, the spool 40 can function to unwind the Tether 402 sueh that the payload 408 can be towered to the ground with the tether 402 and the pay load cou ling appae&tas 412 from UAV 400. The payloa 408 m&y itself be an item for delivery, and may fee housed whfeitt (or otherwise incorporate) a parcels eortfaluer, or ether stJiiCttste that is configured mteriaee with me payload latch 406, ia practice,, the payload delivery .s stem 410 of UAV 400 ma fnnedon to autonomously lower payload: 408 to the ground in a controlled .manner to facilitate delivery of the payload 408 on the ground while the UA.V 400 hovers above,

{017 ! As shows: iB Figure A, the pay load latch. 406 ma be in a closed position(fc.g- _* piss engaging th e p ay lo a d coupling apparatus 412) to hold the payloa 408 against or close to the eoltors of the U&Y 00, or even, partially or completely ins de the OAV 400, during iight from a launch site to a target location 20, The target locabon 420 may be a point i space directly above a. desired deliver location, T¾en, when, ihe UAV 400 reaches the target location 420, the IJ A ¾ control system (e.g., the tethe control module 216 of Figure 2) may toggle the payload latch 406 to an open, position (e.g., disengaging the pins from die payload .coupling apparatus 412), /thereby allowing the payload 408 to he lowered ftorn the UAV 400; The eorstrol system may further operate the spool 404 (e.g., by controlling iie motor 222 of Figure 2) such that the pay load 08, secured to the tether 40 b a payload couplin apparatus 412 , is lowered to the ground, as shown in Figure 4B.

J ^Q I7S Once the payioait 408 reaches me ground, the control system may continue operating the spool 404 to lower the tether 402, causing ovinia of the tether 402. During over-run of the tether 402„ the p oad eonpilag apparatus 12 inay coiuitiue to lower as the payload. 408 remains Stationary on the grbuad.. The downward momentum asd or gravitational forces on the payload coupling apparatus 412 may cause: die payload 408 to detach from die payload coupling apparatus 412 (e.g., by sliding off a hook of the payload. coupling apparatus 412). Alter releasing payload 408, the control system may operate the spool 404 to retract the tether 402 and. the payload costing, apparatus 412; to rd the OAV 400, Once ihs payload couplin apparatus reaches o sears the UAV 400:, the control sy stern amy operate the spool 404 to pull lite payload coupling apparatus 412 into ttse receptacle 414, arid the control system may toggle the payload. latch 406 ^' to the closed position... as shews m Figure 4C,

|01 ¾| In: s me ern x>diraersis/ _: when to wering the payload 408 from the UAV 400, the control system, may detect when the payload 408 and/or the payload coupling apparatus 41 has been lowered, to be at or mm the round based on an unwound length of the tether 402 from the spool 404, Similar techniques may be use to determhre when the payload eospling apparatus 12 is at or near the UAV 400 when retracting the tether 402. As noted above, the UAV 400 ma include as -e coder for providing data Indicative &i the fetation of the spool 404. Based on data from die encoder, fee eotJtrol system may deterr ae ho many rotations the spool 404 has -undergone and, based on the numbe of rotations, determine a length of the tether 402 that is nnwonad frorn .the spool 404. i¾r instance, ifie- control system may deterniiae an unwound length -of the tether 402 by multiplying the auniher of rotatloas of the spool 404 by the circumference of the tether 402. wrapped around She spool 404, la some embodiments, s¾eh. as when the spool 40 is narrow or when the tether 402 has a large diameter, the ciisura srence of the tether 402 o ? die spool 404 may vary as the tether 0 winds or unwinds from the tether, and so the control s stem may he configured to _: account for these variations when dete mining . the unwound tether length.

|!177| in other embodiments, the control system, ma use various types of data, and various techni ues, to determine when die pay load 4 8 and'or payioad coupling apparatus 412 have lowered, to he ai or nea the ground. Farthe , the data:, that is us to determine when the payioad 408 is at or near the ground may be provided hy sensors on UAV 400, sensors on the payioad coupling apparatus 41,2, and/or other data sources that provide dat to di control system.

0178| In some emlxrf imeat s, the control system itself may he situated on the payioad -coupling apparatus 413 and/or on the UA 400, for exampl , the payioad coupling apparatus 412 m iac!nde logic; moduieCs) implemented via hardware, software, and/of fsrinware that cans? the UAV 400 to Mneiios as described herein, and the UAV 400 may include logic modntefs.) that, eoalm nieate with the payioad coupling apparams 412 to cause die II V 400 to perform fe ctifc s described herein.

|Θ179 Figure 5A show a perspective view of a payioad delivery apparatus 500 including payioad 310, according to an example embodiment. The payioad delivery apparatus 500 is positioned within a ftrselage of a UA V (not shown) and includes a winch 514 powered by motor 512, aad a tetter 502 spooled onto winefo 514. The tether 502 is attached to a payioad coupling apparatus 800 posiiioaed within a: payioad coupling apparatus receptacle 516 positioned within the inselage of the UAV (not: shown). A payioad 510 is secured t the payioad eonpUag apparatus O, In this embodiment- a to portion 513 of payioad 510 is secured withi fee fuselage of the UAV, A. ioe!iag pin 5-70 is shown, extending through handle 511 -attached to payioad 510 to positively secure the payioad benead* tire UAV .durin ^' high speed light ,

f 0:1-8 ) Figure S is a eross-seetionaf side view of payioad delivery apparatus 500 and payioad 510 shown in Figure 5A, In this view, die payioad coupling apparatus is shown tightly positkaied with the pay load coupling apparatus reeepfae!e 5.1 _. 6; Teilier 502 extends ^• ftofti winch 514 a is attached to the lop of payfo&d couplin apparatus 800, Top portion 513 ofpayioad 510 is shows positioned withi tie fuselage of (lie AY (not shownl long With handle S3 L

}0 I| Fi ure 5C is a side view of payload delivery apparatiis 500 and payload 510 shown in Figures 5 A and SB , The top portion 5.1.3 of pay load 51 is shown positioned within tte fuselage of the ΙίΑΥ. Winch 514 has been used to wind ¾ tether 502 to position the paylo i coi^!iaji apparatus within payload. coupling apparatus receptacle 516, Figures 5A-C disclose payload 310 taking the shape of s aerodynamic hexagoiialiy-shaped tote, where -the base and side walls arc six-sided hexagons and the tots. Includes generally pointed front md rear surfaces formed at the intersections of the side walls ami base of the tote providing im aerodynarriie shape.

VI» Exawipie Capsules, Rec ptacle, and Package ote.

p 2j figure 6A is a perspective view of payload coupling apparatus SOO. according to : an example embodiment Payload oup! tug apparatus 800 includes tether mounting point 802, and a slot 808 to position a handle of a aytoad handle in. Lower lip, or hook, B06 is positioned beneath slot BO L Also include is an outer protrusion 804 -having helical earn snrfaees SMa. and $04b that are adapted to mate with corresponding e rn mating siirfaces within -a payioad coupling apparatus receptacle positioned with a fcsela e of a UAV, §Ϊ83| Figure 68 is a side: v i ew of pay load: eouphng apparatus 800 shown hi Fi gure

6A. Slot 808 Is sho a positioned abo ve lower li , or ^' hook., 806. As shown lower lip or hooic 806 has an outer surface 806a thai is undercut suc thai it does pot extend as far outwardly as an outer surface above slot 805 so that the lower lip or hook 806 will not reengage with the handle of the payload: after it has been decoupled, or wilt not get engaged with power lines, or tree branches durin retrieval to the. UAV.

fil8 | Figure 6C is a front view of pay load coupling apparatus 800 shown in Figures

6A and 6B. Lower li or hook 806 ^' is shown positioned- beneath slot 808 that is adapted for securing a asdle of a pay load.

{0J;8S| Figure. 7 is a perspecti ve view of payload couplin apparatu 80 shown in-

Figures 6 A-6C, prior to insertion into a pay load ^■ coupling- apparatus receptacle 51.6 positioned ½ the fuselage 550 of a liAV. As noted previously payload couplin apparatus 800 includes slot 08 positioned ahove lowe hp or hook 806, adapted to receive a handle of a payioad,: The friselage: 550 of the payload delivery system 500 ^; feelsdes a payload eooplsg apparatus receptacle 51 positioned within the fuselage 550 of the UAV. The payload coupling

surfaces 8.10a and 810 b shows: in Figure 7:. In this snanner, the rounded or Ma l apex of canirned surfaces 81 On and 810b prevent possible jarnrning of the payload coupling apparatus 800 as the c mmed surfaces engage the cammed stsrfaces 53& and. 53013 positioned within the payload coupling apparatus receptacle 516. positioned within fuselage 550 of -the UAV ^" , In particular, canned surfaces 804a and 804h are positioned slightly higher than the rounded or blunt apes of eatnr»ed snrfaees 810a and $10h< As a result, the sharper ti of eatnmed surfaces 804a and 804b engages the eatnrned surfaces S30 and 530b within the payload coupling apparatus receptacle 516 positioned within, the fuselage 550 of ^" payload eliver)' s stem 500, thereby initiatin otation of the payload coupling apparatus 800 slightly: before the rounded or blunt apex of eannned surfaces 810a and 810b engage the corresponding carnmed surfaces within flic payload coupling apparatus receptacle 516. in. this manner, the case where both apexes lor tips) of the casnmcd surfaces on the payload eonpiing apparatus end u on the same side of the receiving caps within the payload coupling apparatus receptacle is prevented. This scenario results hi a prevention -of the jasnniri of the payload coupling apparatus wSit la the receptacle.

jy i87f Figure 9 shows a perspective view of a recessed -restfafm slot a id payload coupling apparatus receptacle positioned la; a fuselage of a tJAV, In particular, payload delivery system 590 includes a fuselage 550 ving a payioa coupling apparatus receptacle 5 6 therein that includes in ard protrusion 530 having cammed surfaces 5:30a asi S30o that are adapted to mate with corresponding cammed surfaces on a payioad coupling apparatu (not shown) _* Also included: is a lorsgitudma y extending recessed restrained slot 540 into which a top portion of a payload is adap ted to e positioned arid eeu d within the fuselage 550.

fOlSSf Figure IDA shows a side view of a payload deliv r)' apparatus 5.00 with a han d le 311 of payioad. 510 secured within, a payload coupling apparatus 800 as the pay load 5 K) .moves downwardly prior to touching down for delivery. Prior to payload touchdown, the handle 51 1 -ofp¾ loi¾ ^' 5l0. iiiciu e8-a ^' -h¾«-5i3 through which a !ower S p or hook of payload coupling apparatus 800 extends. The handle sits within a slo of the payload coupling a paratus 80 that is suspended front tethe 5§2 of payload deiivery system 500 during descent of the payload 510 to a landing site.

\%lW i Figure 10B shows a side vie of payload delivery apparatus 500 after payloa 510 has landed on the .ground, shewing payload eoaphug apparatiss 800 decoupled from handle 511 of pay load: 510. Once the payload 510 touches the ground, the payload coupling apparatus SO continues to move downwardly (as the winch further .unwinds) through inertia or gravity and decouples the lowe li op hook. 80S of the payload co pling apparatus 800 fir «J: handle 51 1 of payload 510, The payload coupling apparatus 800 remains suspended, f om tether 5 2 _s and can he winehe hack up to the payload coupling receptacle of the UAY. f 0 I *¾ ^} { Figure 10C shows a side view of payload deliver apparatus 500 with payload coupling apparatus 800 moving away from handle 511 of payload 510, Here the pay load coupling apparatus $0t ⁾ is completel separated ftotn the hole 513 of handle 511 of payload 510. t ethe 502 may be used to winc the payload coupling apparatus back to the payioad coupling apparatus receptacle positioned in the fuselage of the UAV _;

|θ ί 911 Figure 1,1 is a side view of handle 511 of payload 530. The handle 511 includes a hole 513 through- which the lower ^' lip or hook of a payload. coupling, apparatus extends throngh to suspend the payload. during delivery. The handle 5U includes a lower portion 51 that Is secured to the top portion of a payload. Also included ^' a ? h&les 514 and 16 through which locking pins positioned within the fuselage of a UAV may extend to secure :the handle and payload in a secure position ring high speed forward Bight to a deliv ry location. The ha fe-.may be comprised of a thin, flexibfe plastic material that is flexible an provides sufficient strength- to suspend the payload beneat a U&V ^' daring forward flight to a deliver site, and during delivery ando retrieval of a payload, in practice, die handle may be tot to position the handle within a slot of a payload couplin apparatus. The handle SI I also has sufficient strength to withstand the torque doting rotation of the payload coupling apparatus into the desired orientation within the payload couplin apparatus r ceptacle; and rotation: of the top portion of the payload into position with the recessed restraint slot.

{&192$ Figure 12 shows a patr of locking pins- 5?0 _> 572 extending through holes 51 and 5.1 in handle 5.1 ϊ of payload 510 to secure the handle 51.1 and top portion of payload 510 within th fuselage- of a UAV. In this nmnner, the- handle 51 1 and payload 510 may be secured within the fuselage of a ^' UAV, ¾ this embodiment _* the locking pins 570 and 572 have a conical shape so that they pull the package up slightly or at least .remove ^' any do n rd slack present. I» some embodiments Ihc lockin pins 570 and 572 ma com letely phig the boles 51 and 516 of the handle Si 1 of payload 510, to provide a very secure attachment of the handle and top portion of the payload within, the fuselage of the DAY. Although preferably the locking pins are conical in other applications they may have other geometries, such as a cylindrical geometry,

f J93 Figure 13A is a perspective view of payload coupling apparatus 900 prior to having a handle of a payload positioned within, slot 920 of payload coupiiag apparatus 900, Payload coupling apparatus 900 has a tether slot 906 on inner surface 904 of portion 914 into which a tether .902 is inserted. Also included is a pair of upwardly extending fingers 908 and $10 having a slot 912 positioned therebetween, A handle of a payload may be inserted into the slot 920 o payload coupling apparatus 900 .positioned between upwardly extending fingers 90¾ and 910 and inner surface 90 .

|Μ 4| Figure I3B is a perspective view of payload coupling apparattis 900 aiter delivering a payload and decoophng the payload couplin apparatus 9 (1 from a handle: of a: pay load:, Irs. this embodiment _s the upper portion of portion 914 is weighted such that when the payload coupling apparatus 900 is decoupled from the handle; of the payload. the payload coupling apparatus 900 rotates J i degrees such that the fingers 908 and 10 are downwardly extending, thereby preventing the slot 930 free. : reengaging with the handle of the pay load., or engaging with tree branches or wires doring retrieval to the fuselage o the IIAV, During rotation following decoupling, the tether 902 is polled from tile tether slot 906 {shown in Figure 13A) and passes through slot 912 between fingers 908 and 910 suc that ^' the payload coupling apparatus 900 is suspended front tether 902,

f0i95| Figures 14A-E provide various views of payload coupling: apparatus 900 shown ¾ Figures !3A arid 13:8; As shown $a Figures Ϊ Α-Ε. the payload coupling apparatus 900 includes a slot 920 positioned between upwardly extending fingers 908 and 910 an i m surface 904., A tetter slot 906 is positioned in mm surface 904. A slot 912 also extends between upwardly extendin fingers 9 8 and 9 10. A tether attachment poin 922 is positioned on a bottom of the payload c pl ng apparatus 900, The tether slot 906 extends irsm: tether attachment point 922 to the top of inner surface 904, U per portion 91 of payload coupling ap aratus 14 is weighted, such, that upon payload landing, the payload coupling apparatus i automatically decoupled ironi the handle of the payload, and the weighted upper pardon 914 canses the payload coupling apparatus 900 to rotate: downwardly 180 degrees. Darin this period of rotation, a teiher is pulled free from tether slot 906 and the payload. coupling apparatus is suspended horn the UAV via the teiher attached to teiher attachment point 922 with, fingers 90S and 910 pointing downwardly. As a result, the fingers § and 910 arc prevented fito&i sagagiag die handle of the payload when retrieved; to the UAV, and also prevented from engaging tree branches or power lines dnrsag retrieval to the UAV. Although not shown la Figures 14A-B, the payload coupling apparatus 900 could also include carnaied surface* as shown in payload coupling; apparatus 800 that: engage with ajatlng cam positioaed: withia a payload coupling apparatus receptacle la the fuselage of UAV to orient the payload coupling apparatus in a desired orientation within die payload coupling apparatus receptacle.

f0i96| Payload coupling apparatus 900 also advantageously is a solid state design thai includes no movin parte, thereby reducing the complexity and cost of the payload coupling apparatus and eliminating movin parts that cm possibly fait A more .reliable payload conpling apparatus is thereby provided,

t97J Figure I5A-E provide various views of payload coupling apparatus i HJO, lt% this embodiment, payload coupling apparatus 1000 has generally spherical shape, A slot 1.020 is positioned between, enter lip or hook iOM and: .rounded, portion 1014. The slot .1.020· is adapted to receive a handle of a payload. A tether attachment point 1022 is positioned on rounded portion 1.014. A: tether slot 1006 extends from tether attachment paint 1022 t slot 1020 and is adapted to receive and hold a. tether. Rouiaied portion 1014 or portion 1010 may he weighted such thai when a payload touches the gronnd, the handl of the payload. is decoupled from. She slot of payload coupling apparatus 1000, Durin decoupling frons the coupling apparatus f om snagging dnring descent fern, or retrieval to, t e fuselage of a UAV- j0203 The preseni eaibo mc¾s prov de a highly mtegrated winch-based pickup and delivery system for IJAYs, A nataber rf significant advantages are provided.. For example, the ability to pick up. and deliver packages without . ^' the seed fo landing is provided, as the system is able to winch u a package with the aircraft hovering. Although in som locations, iirfra tructere such as p!atforo o perch fo laad g or loading the IIAV ma be provided, in other location there may be no need for mftastcuciure ^' at the merchant or custome location. The advantages include high mission fiexibilify sad potentially .little.; or ftp. in#as:imctere installation costs, as well as increased flexibility in payload geometr ...

f&284| hi addition, the payload delivery system, may automatically align the top portion of the payload during winch up _s orissting it for minimum drag along the aircraft's longitudiiial axis. This aligainent enables high speed forward flig t after ick up. The a|i e«t is accomplished' through the shape of the payload book and receptacle. In the payload. couplin apparatus 800, the lower Hp or hook 806 has earn features around its perimeter which always orient it in a defined difee!iou when it engages into the cam features inside the reeeptaeie of the fuselage of the UAV, The tips of the cam shapes on both sides of the capsule are asymmetric to prevent jamming in the 90 degree orieata oa.- 1» this regard, ^' helical cam surfaces ma meet at an apex on one side of the payload coupling mechanism, and. helical cam surfaces m y meet at a roiraded apex oh th other side of the pay load coupling :raechani$r«. The hooli is speeliealiy designed so that the: package hangs in the ^• ceaterline oiihe hook _s enabling alignment in both directions from 90 degrees.

fO205f Payload coupling apparatuses 800, 800% 909 ₍ and 1000 include a hook formed about a slot such that hook also releases the payload passively aad automatically wh n the payload touches the ground upon, deli very. This is accomplished through the shape and/angle of the hook slot and the corresponding handle on the payload. The hook slides off the handle easil when the payload touches down due to the mass of the capsule and also the inertia wantin to continue moving the c&psuie downward past the payload. ^' The; end of the hook is designed to he recessed slightly from the body of the capsule, which prevents the hook, f om accidentally .reattaching to the handle. After successful release, the hook gets winched hack u Into the aircraft. All this funettmialil (package ali nment during pickup, aad passive elease: during ^' delivery) Is achieved wit ut any moving parts in this payload coupling apparatuses 800, 900,. and 1000 (referred t as a solid state design). This greatly increases reliability and reduces cost The simple design also makes user imeraetion very clear and seit-expianaiory,

Vlf » Tef her CoHtrei Oaring Payioad Pickao

f 02861 A UAV may be able to pick u an deliver a payioad without landing. In. some examples, the UAV ma be able to raise and lower a pay!oad coupled to a tether by winding and unwinding i tether while hoveriag. As suc&, _: the UAV may pick up and deliver the payioad. wit!out requiring infrastructure to he se u by 3 merchant, or customer, tirerehy increasing a flexibility of delivery location and/or payioad. geometry arid decreasing or eliminaiiftg costs associated with the manutseiure or installation of iafrasirnciure. In oiher exariiples, the UAV raay be epnt1:g ire to land on various elevated structures, such as a perch or shelf, and, ¾orn its elevated landing pos os, pick tip or deliver tile payioad by winding or unwinding the tether,

|¾2I 7| Figure 17 sho ws a-methpd 17 0 for tethered pickup of a payioad (e. g., a. package) for subsequent delivery it* 3 target location, Method 1700 ma be carried out by a. ^' 0AV such as those described elsewhere herein. For example, method .1 ΊΜ i y be carried oat by a control -system of a. UAV with a wiaeh system. F rt er, the mch system may

Mclnde a. tether dispose OR a spool, a motor operable in a -first mode and a secou&mode that respectively counter an assist uowindii¾ of the tetber d«e to gravity (eg. , by dmwg the spool forward or its reverse) _* a, payioad coupihig apparatus that mechanical ly cowpies the tetber to a payioad, and a payioad latch switehable between a closed position thai prevents die payioad from being lowered frost) the U V and as open position: fiat allows tbe payioad to be lowered from tbe UAV,

|Θ2Θ§ As shown by block 1702 of method 1700, wbeu tire UAV arrives at a pickup location (also referred to as a source location), the OAV¾ control, system rriay opea tbe payioad latch, such thai tbe tetber and. the payioad coupling apparatus cars be lowered toward the ground at tbe pi ekup _: locution.

At block 1704, the control system operates the motor to unwind predetermined length of tbe tether. This unwound length ma coi espo-ud ^' to- aft expected payioad attachment altitude for the payioad coupling apparatus, which is attached io tbe lower end of the tether. The payioad -attachment altitude may be an altitude at which a - uman, or perhaps 3 robotic device, may grab die payioad coupling apparatus for attaching the coupling; apparatus to a payioad. For Instance, the payioad attachment altitude may be an altitude less than two meters ab ve ground level. Other examples are possible as weiL [0210} After unwinding the predetcmimed length of the tether, ike control s stem may wait to a predetermined payload attaehnie t period, as shown ^' by ^' block 1706:. ^' This- attachment period allows ia«S ifcr a human, or perhaps a robotic device, to attach a payload (e.g., & package to delivery) ίό the payioad. coupling apparatus. Tie predetermined payload aitachrnest period may be a fixed value or May vary based B art operational state of the OAV,

receptacfc. hi particular, when the calculated unwowu length of tether is at or near zer , this may indicate EMt the payload coupling apparatus and/or the pay load have eea lifted all the way to the V Further, hen the paylaad coupling a paratus and or the payload: contact the UAV's receptacle area, the motor ctrrrent may increase as tile motor's speed c aitrolfe attempts to continue paling the payioad upward. Arid, by considering both these indications, th control system may avoid false positives.

i S| Thus, upon detecting both, of the abovc-deserihed indications, ike control system may respousively operate tfee motor is the first mode to pull the payload. into _s and oris¾t the payload within, he receptacle oft the lower surface of the UAV ^' , as sfeffi n by block 1716. In particular, the control system may operate the motor to increase the torque applied to the tetiier, such as by Increasing die eurreftt supplied ^' to the motor to predetermined, value, in order to help ensure that the payload coupling apparatus (and perhaps the payload as well) are firmly seated against the corresponding surfaces of the JJAVs i¾cep:tae.le, such that the payload. latch (e,g, _< pins 579 and 572 of Figure 12) cm be closed to secure the payload for flight to the target location. Accordingly, after applyin torque to trie tether in an upward, direction for a predetermined peri d of iwe , ifte control system ma close tie payload latch, as shown by M ck 1718. With the payload seetue for flight, the tJAV may navigate to target location tor delivery.

VOL Tether Cent al Durin Faylo&d Delivery

&2161 Once the UAV arrives at the target ioeatioa for ddivery, the UAV's control system may responsively operate i a delivery mode . Figure 1.8 is a flow chart illustrating metliod. 1800 fo operation of a UAV hi a delivery mode,, according to an example embodlrnem,

|021:7f Mote specifically, once the UAV arrives at and is hovering over a target location for tethered delivery, the OAV's control system may operate the motor to unwind the tether accordin t a predeterm ed descent, profile, as shows by block 1802. The predetermined descent profile may control a descent rate of the payload by speeifydiig a desired irotatienal speed of the motor., for example, the descent profile imay specify- a: constant descent rate or a variable descent rate for the duration of the payload descent.

|Q21B| la some examples, the desired rotational motor speeds specified by the redetermined descent prof le could be based on maenine-ieame i data that could be inferred om data from, prio flights. For e ample, for ^' delivery to a a ti ular location, the control, system could use a descent profile that was previously used during a previous delivery to the particular location. Alternatively, if use of the descent profile during a previous delivery to that particular location o $®s - ether location rssnlied ¾* »* or more detected errors -(e.g., failure to detach, the payioad from me tether, damaged pay load, etc,), men the control system couki alter the descent profile .ie,g, _: , _. by increasing of decreasing the- desired motor speeds duriftg various p ases of the pay!oad. descent) or choose to ose a default descent profile insiead.

i&tl la an. exam le method, the control system may not exert significant control ^' over the descent of the pay load until ft is closer to die ground. For instance, at some point while the icthcf i$ unwinding, the control system may detemhne that the an ousd length of die tether is greater dian a threshold length, and respottsively operate in. a pm-tonchdown mode, as shown by "block 180 . The threshold, -.length may correspond to a prcdeteom ^' nefl near-ground altitude of the payload: e,g., a height where more control is desirable lor tfse safety of bystanders and/or ground structures, arid/or to protect die payload and. its contents from, d mage,

p228f As note _* in the pre-touchdo n mode, the control s stem may pay close attention to the pay load to improve the chances of successful release of the payload on the ground, hi particular, while operating hi the pre- oaeMowu Mode, the contxol sy stern operates die motor such that the tether continues to unwind accordin to die predetermined descent profile, as shown by block 180 a,, while monitoring both, motor current and moto speed, as shows by block 1804b. The motor current may be compared to predetermined payload-uacoiipling eurreut to detect when the motor current is less than _: the predetermined p yioad- sconpiirig current. Additionally, the rooter speed may be compared: to predetermined pa ioad-uueoiip!hig speed to detect when the motor speed is less than the predetermined payload«-trncoupling speed, as shown by block 1804c. When both the motor current is less than a predetermined payload-ttncouplng current and the motor speed is less than a predetcrroined payload-iracoupiing speed, the control system responsively switches to operation in a possiblc-touchdo n mode.

22 i] The possible-touchdown mode may be implemented in an -effort to verify that the package has, in fact, reached t e ground, (or put another way, to help prevent false positive detection of contact with, die ground). For instance, while operating in the possible- touchdown mode, the control system may analyze the motor current to verif that the motor current remains below the predetermined, payload-uncoupiin current for a toue&down- veriication period (e,g., perhaps allowing for a small amount of fluctuation dtsring this period), as shown by blQcjk 181)6 ^" . In ractice, a Sebrsitt trigger may be applied to verify that the detected drop in rnotor current to below me payload-uncoupling threshold is not the result of noise or some temporary blockage, and is in fact due to die payload resting on the ground. Other techniques for verifying touchdown of the payload ; are also possible.

J0222 Once touchdown of ike payload is verified, the control system operates he motor such that oyer-ras of the tether and payload coupling apparatus occurs, as shows by block 1808. Qver-rttrs . occurs when the payload comes to a test while ihe tedier continues to unwind, in practice, for example, die control system- may switch the winch motor front the first mo z to the second mode fey, .e.g. _s reversing the direction the motor and thus the direction, of torque applied to the tether by {¾© motor _* Thus, the motor may switch ^' firora slowing the descent of the tetter to forcing the tether to unwind such that over-run of the tether occurs. The over-run. of the tether ma in turn lower the payload c upling apparatus below a height where coupl n to tile payload occurs .(and perhaps all ire way to the ground), la other embodiments, block 1.808 may involve the control system simply taming the motor off, sad allowing gravity to pnl! the payload cottpli g apparatus down and cause the tether over-run.

[0223| ftirtte as shown la Fipres 6A-6C. lOA-IOC, -and I I , the payload and/or payload coupling apparatus may have miertaeing surfaces such that the interaction of the payload and payload cou Bag apparatus during over-run deflects the payload coupling apparatus to the side of the payload. As sucti _* the .coupling feature of the pay load coupling apparatus (e.g , a book) will no louger he aligned with a correspondiiig coupling feature of the payload (e.g., a handle on a tote package). Located as such, me winch system may retract the tether an payload coupling apparatus to the UAV without the payload coupling apparatus re-coupling to the payload, thereby le ding the package oft the ground.

[0224} In some examples of method 1800, the control system may be configured to, prior to openin the payload latch, operating the motor to apply an upward force on the tether. This may allow for the payload latch to he opened more easily, as the payload may be arranged to: rest some or all of its weight on the payload latch when the latch is in the closed .position. The weight of the payload may increase the f iction against the payload latch when attempting to switch: the latch to the Open position, so lifting the payiaad. a predetenihned amount may reduce occurrences of the payload iateh getting stuck in the closed position. Additionally, after openin the pay bad latch and before unwinding the tether, the control system, may fee configured to operate the motor to hold the tether in a substantially constant position. This may allow the weight of the payload to pull the payload downward and against the paylo coupling apparatus, causing the payload to become firmly seated in a coupling mechanism (e,g., a hook) of the payload coupling apparatus. IX _* User 'Interaction and Feedback, via Control of Tether

}Θ225| ^' Μ practice, a user may internet with the disclosed winch systeni ia various ways afid for various .'.reasons. For instance, the user may interact wit tlse wiiseli sptem to .manually couple or decouple a payload to the tether via the payload coupling apparatus;, such as for payload delivery purposes or for payload pickup purposes. I» doing so. the user may apply forces directly onto the tether and/or may apply forces to the tetlier via the payload coupling apparatus., .a ong ^■■ other possibilities. Moreover, such interaction with the winch system may effectively also amounts to an iateraetiop: i¾ the OAV itseif because the UAY could a< )ust its ope atioH based oft those fetees (e,g,, _: the AY iftay engage in flight stabs ligation that accounts fo those forces).

[02261 When the user interact with, the disclosed winch system,, the user eoakl e couBie various challenges. For example, the user ma not know how the interaction with the winch system may ultimately affect operation of the winch system and/or operation of the llAV, As a, result the user could niadvertently damage the O V and/or the winch system. In another example _* the nse.r. may not know any ruture operations that the SJA V and/or the winch system plan to carry oat A a result, the user coul d iftad:verteiitly stop the UA and or. tie winch system from cany tug. out a planned operation. In yet another exam le, the user may want the IJ V and or the winch system to carry out a certain operation, but raay not have me means to control operatioa of die OAV r of the winch system. Other examples are possible as well,

( ^' 0227J To help resolve such challenges, the disclosed winch system m fee configured to control the tether so as to interact with and provide feedback to a. user. Specifically, the UA.V*$ control s stem ^' may be equipped with the capability to interpret direct or indirect user interactions with the tether, perhaps carrying out certain operations in response to the interpreted interactions. Also, the tiAV ^' s control, system may be equipped with the capability to provide information to the user by ma pulatjag the tether, perhaps doing so in: response to a user interaction with the tether.

2281 figure: 19 illustrates a method i9iM) lor faicil stating coatrol. of the tether fer purposes of interacting with anil/or providing feedback to a user. As shows by Mock 1902· ol ^* method 19Θ , the lIAA ^" s control system may determine .e s .or goat oj>e«ation¾i parameters of a motor for a winch disposed in an aerial vehicle, the winch including a tether and a spool. Then, the control, system may detect in the one or more o eratio al parameters, an operational pattern of the moto that is indicative of an infentioHal nser-ipteraetioH with: the tether, as shown by block 1904 of method 1900, Based on the detected operational pattern o ^• fiie motor that is iridieative of the intentional «ser-ratemetioa.- W-iih ^' the ^■ tether, the control system may ietefoftifce a Mot r response process, as shown · block 1906 of i»eiSiod 1900. And s shown by block of method 1900, the control system may then operate the motor in accordance with the determined motor response process.

i, D& rmimng Qp&rttiami Pa mefers motor

|022 } As noted above, the WAV's control system ma determine one or more operational parameters of the motor. In praeti.ee. art operational parameter of the motor may be an measure of the motor's activity.. Aimotsgh certain operational parameters are described herein, other operational parameters are also possible without departing from, the scope of the presen disclosure.

|0 3Θ1 By way of example^ an operational paramete of ilie motor may be current characteristics of the motor, such as a current level being provided to asd br generated by the motor over time or at a particular instance in time, among other possibilities. In another example,, an operational parameter of the motor may be speed characteristics Of the- tnotor., such as a speed, of mtatioti. of the motor's transmission assembly over time or at a partietdar instance in time, among other possibilities, Irs yet another example,, it operatiot parameter of the motor may be rotation ehariteteristies of the Motor, such as an extent of rotation of the motor's transmission assembl over me, among other possibilities. Other examples are possible as well.

023il Generally, the control system may determine one or more operational parameters of the motor n various ways, For instance, the control system may .receive,, fern one or more sensors eoiip!ed to motor, sensor dat indieadve of operational parameters. Once the control system receives the sensor data, the control system may then e the sensor data to determine arid/or evaluate the operational parameters of the motor..

f§232| By way of exam le, a current sensor may be coupled, to the motor and configured, to generate current data indicative of a current level being provided to and/or generated b die motor. With this arrangement, the eostjol system may receive current data from the einrent sensor and may nse the received current data as basis to determine eiarent characteristics of the motor. For instance, the control system may wse the received current data as basis to determine particular ctrrrent: level of tire motor er a particniar time period.

In another example, a spee sensor may he couple to the motor and configured to generate speed data indicative of spee of rotation of the motor 's transmission assembly. With this arrangement, the control system may receive speed data rom the speed sensor and may use the received current data as basis to determine speed characteristics o the motor. For instance,, the control system may use the received speed data as basis to determine a particular speed of the motor at a particular point, in tkne.

0234| lh yet another exam le _* encoder msy be coupled to the motors transmission assembly and configured to generate position data representative of the transmission assembly's over time. With this arran ement the control system may receive position data -from foe -encoder and may use the received position data as basis to determine rotation characteristics of the motor , For instance, the control system may use the received position data as basis to determine an extent arsd/or a direction: of the transmission, assembly's rotation ftom a first point i time to a second point in time, Other examples and instances are possible s well,

}023S| Figure 20 ^' next shows a- graph Minstrative of example current, characteristics

.2.000 of ^' foe motor. As shown., the current characteristics 2000 represent the motor's current, level o er time. In practice, the current, level may change over time ased on various fee-tors. For instance, the eim-eni level may change based on to q«e/fdree that the motor seeks to provide (e.g>, to the tether) and/or based on an external torque/ibrce provided to the motor Ce.g., via foe ted¾er), amon other possibiliies. Other examples are possible as well ii. Defecting m Ope atiomi Pattern &fth& Motor thai is rt imtt User^Jnter eti {-§2 { As noted above, foe control system m detect, in foe one or .more e rstoml pararneters, mi operational pattern: of foe niotor that is indicative of an- intentional aser- interaeiion with the: tether. ^' In practice, an operational pattern may be any contiguous and of nan-contiguous sequence of values of one -or more operational parameters over time. Moreover, the control syste may use any currently known and/or future developed signal processing techniques or the like to detect an operationai pattern. Nonetheless, a operational pattern eoo take various forms,

f 237| In one c^se, an. operational pattern, may be a pattern found In a single operational parameter. For ins.tan.ee, an operational pattern may be a particular pattern of current characteristics, such as a particular set ence of current levels being represented by current data over time. In another ease, however, an operationai pattern may involve patterns respectively found in two or more operationai parameters over the same time period and&r over different respective time periods. For instance, an operational pattern may be a ^• particular pattern of current characteristics over a first time period as well as- a particular pattern of speed clsaraeteristtes over a second time period (e.g., sarne as or different from the first time period:).. Other eases are possible as well | 23S| Given the above-descrihed amuigenrent, the control system, detecting o|seraiiotiai pattern may involve the control system defectin var ions patterns among ί β or more determined parameters. By way of example (md without hmiiation), the control .system delecting m operational pattern may involve the control system detecting any combination of the .following: a particular atiye change of motor e enf, a particular fate ■of change of motor current a particular motor current value, a. particular sequence of motor current values, a partoilar relative change of motor speed, a particular rate of c an e of motor speed, a particular motor speed alue,. ¾· a^sal - ^aob of motor speed values, a particular relative change of motor rotation, a particular rate of change of mot r rotation, a particular motor rotation value, arsd or a particular sequence; of motor rotation: values, among others.

|0239J hi accordance with the present disclosure, as noted, detecting an operational pattern may specifically involve - detecting an operational pattern of the motor that is indicative of an intentional user½tef8C ion with the tether. More specifically _* when a user interacts with the tethe in a particula manner, the motor may exhibit a particular operational pattern. As such, established operational patterns (e.g., established vis manual engineeriug Input) that the control system can detect may each correspond to a. respective user-interaction with the tether, la this way, when the control system detects a particular operational pattern _* the control syste may effectively detect a particular iiser-interaetioh wit the tether; la practice, the control system may do so simply detecting the operational pattern and without there necessarily being a logical indication Of a irser-interaction,

| 249| In some cases, however, fee control system may maintain or ma otherwise refer to mapping data that maps each of a pluriiiit of operational patterns of the motor each with a respective user-dnteractlon. For example, the mappin dat may map a particular current level pattens with an Indication of a user providing a particular downward force on the tether. & practice, the particular downward force may he a force that is applied In a direction swhstantMly perpendicular to a ground SMrfacc and/or ma be a force that Is applied in a direction that is at another angle (e.g., 45 degrees) relative to the ground ^' surface fe.g., such as when a user catches an. oscillating tether and then tugs o it at art angle), in. another example, the mapping data ma map particular speed level pattern: with an indication of a user moving the tether side to side at a particular rate. In practice, such indications could each take on any feasible forms, soch as the form of letters, ntmibers, and or logical Boolean values, among others. Accordingly., when the control system detects a particular operational pattern, the control system ass refer to the niapping data to determine the oser-iuteraciion that is respectively mapped to that particular of erafional pattern,

02 11 Moreover, different operational patterns may sometimes be indicative of the same user-interaction. For dns reason, tke control system may be arranged to detect a first operational, pattern and. fhtfs effeetively detect a particular user-interaction with the tether, and ma also be arranged to detect a second operational pattern and thus effectively detect the same ^■ ■particular aser-interaction with the tether, such as for . urposes of determining a motor response process as farther described below. Alternatively, two or more operational patterns in the mapping date could each be mapped to fee same ser-iMeraetion, s feat the control system, detects the saote Mser-interacti-Qn when referring to either one of those operational patterns in the mapping: data. Other eases are possible as weit

J02421 Yet farther, when variou detectable operational patterns are established, at least some. of those established pattern coul account for various external forces that may be applied to the tether, such as external forces other than just those being applied by a user disring an. interaction with the tether. In particular, the operational pattern t y account for gravity, external forces based on weight: of the payioa cou lurg apparatus, and/or external forces based on weight of a coupled payioad (e.g., a weight of a package to be shipped}, among others, in this way, the- control system :may be able to detect art operational pattern of the motor that is exhibited when such external forces are applied in combination ^' with external forces that are based on a user-iBtejactios. Oter external forces are possible; as well |ίϊ2 3| In ye a further aspect in addition to o instead of the above-mentioned mapping data, the control system may use one or more oilier approaches to determine a user interaction based on art operational pattern of the motor..

(02441 In one ease, the control system may carry out signal processing and/or analysis techniques to- -determine YalueCs and/or trendCs) of signal. (e,g>, a signal representative of motor speed values) and to determine the user-iuteraetiou based on those yalue(s) and or tread(s) of the signal. For instance, the control system m y evaluate a set of conditions of signal so as to determine whether or not. all conditions within the set are determined to be true. If the control system determines that ail conditions of the set are true, the control system may determine feat fee signal corresponds to a particular user-interaction. Ofeerwise, the control system, may e valuate another set of conditions so as to determine whether or not ait conditions within that other set are determined to be tee, and so OR. In an example of this approach, the control system may determine whether or not a slope of the signal is within, a particular range of slopes and may determine whether -or not a value of the signal exceeds a particular threshold value within a particular t reshey extent of time. And the- control system niay determine that fte signal corresponds to a pattretiiar lisewftieraciion if the control .system determines both of drese con itiosis to be true. Oilier examples are also possible.

f0245| I» another case, the control system ma carry out probability analysis techniques to determine die «sef«mteraction. For exam le, the control syste raay determine that a detec ted operafioBal pattern does not precisely match one of the operational patterns of the mapping data and thus may apply probability analysis to determine he operational pattern of tbe mapping dat to which d deteeted operational, patters matche wit the highest likelihood. For iostaoce, when defeflSirhng the Watch, die control system ma give a higher weight to a certain portion, of the detested signal patterii eoriipared to the weight given to other portions of the detected signal pattern, thereby applying an additional factor to determine the matching operational pattern and thus to ultimately the user*interaction based on the mapping data. Other cases and examples are possible as well,

[0246! Figure 21. next illustrates an example operational pattern of the motor that is indicative of a particular user-interaction widi the tedier. As shown, die control system may detect a. particular ciateat. spike 2002 in fte aheve-deseribed current eiMitaeteri sties 2000. to d so, the control ^' system, rra detect a particular increase in. current level over time t¾ijowed by a. particular decrease in carreut level over tirae. Additionally or alternatively, the control system ma do s by detecting, a particular rate of increase la current level over ime followe by a particular rate of decrease of current level over time, h either ease, the particular current: spike 2092 is shown as: being Indicative of g particular user uteraetion 2110 involving a particular downward force heing applied^ to a tether 2102.

|0¾47f More specifically. Figure: 21 sh ws a DAY 2100 that Includes winch system 2106 with a motor configured to control io emes of the tether 2102,. As shown, a user 2108 physically interacts with a pay toad coupling apparatus 2104 that is coupled to the tether 2102. In doing so, the user 1 8 applied a downward force to the tether 2102 via die payioa couplin apparatus 210 . ^' the downward feree havin a. magnitude of '' T'. As such, the particular current spike 20O2 is Indicative of a user applying to a tether a downward, force havin a magnitude of 'Ft". Other examples are possible as well.

tii I)etefwMmg a Motor pome Process

{024$f As noted above, the control system may determine a motor response process and o so based on rile detected operational pattern of the moto that is indicative of the intentional nsw-iniemeiion with die tedier. I practice, a particular nioior response process may i&vdlve one or moft ^' particular operation by ike otor, such as appSieatida of ne or more patiieitiar torques onto the ^' tether for instance. Moreover, a motor response process may he arranged so as to cause the winch -system .to interact with the nser via me tetter and/or to provide feedback to fee user via the tether,, among ofeer possibilities,

}0249| In accordance -with the present disclosine, the control syste may determine tire motor response process in various ways., in one case, the- control system may .have stored thereon, or may otherwise be configured to refer to mapping data: that maps a plurality of operational patterns each wife a respective motor response process- lor instance, the mapping data may map a particular sequence of speed levels with a m tor response process nvolving the motor applying, one or more particular tor jties to wind fee -tether: As such, the control system, may detetnvine fee Motor response process by referrin io the trap i data to determine the respective motor response proeess that is mapped to the deteeted operational pattern of the motor .

0258f In another case _* fee control system may aoioally .determine the particular ^' user- interaction with fee tether feat is indicated by the detected operational pattern of the motor, such as by referring to the above-described Mapping: data that maps various operational patiertis respectivel to various respective usef-Mleraeiions. And the control system ma then use the determined particular uscr-mteraetion as basis for deterraintiig the motor response process,

|02S1| More specifically, tSie control system Ma have stored thereon or May otherwise be eonf gtired to refer to mapping data that maps a pluralit of user½teracttons each with a respective motor response process. For instance., the map in data Ma map particular side to side movement of the tether by a user with a response proeess involving application of a particular torqtie to unwind the tetter for a particular duration. As such, the control system may determine fee motor response proces by referring t the mapping data to determine- fee respectiv motor response proees that is mapped to the -particular user- interaction, which was originally determined based on the above-described mapping data that maps various operational patterns to various respective user-interactions. Other eases are also possible-.

|0252f In a further aspect, in addition to or instead of Mapping data, the control system may use One or more other approaches to determine a motor response proeess.

f 0253J In &m ease, the control system ma cany* out signal processing and/or analysis techniques to determine vaine(s) and/ or irend{s) of a signal (e ,, a signal representative of motor speed values) and to determine the motor response process based on those value(s) aad Of trettd(s of me signal Fo instance, the control system may evaluate a. set of conditions of a signal .so- as to dsterh&he. whether or not all conditions- ithin the set are determined to- be troc. if the control system determines that ail conditions of the set are tree, the control system may determine that the signal corresponds to a particular motor response proeess. Otherwise, the control system may evaluate another set of conditions so as to. determine whether or sot a!i conditions within that other set are determined to be true, and. so on. In an example of this approach, the control system, may detemnne whether -or not the ■signal includes an inflection point and may determine et er or ot. a value of a local maxim of the signal exceeds a particular threshold value. And the central, system may deterhiine that the signal corresponds to a particnlar motor response: proeess if the control system determines hoth of these conditions to he true. Other examples are also possible, }0254) 1» another ease, the control system, may cany oat probability analysi techniques to deterntiae the motor response process. For example, the control system may determine that a detected operational pattern does not. precisely match one of the operational patterns: of the mapping data and dins ma a ly probability analysis to determine the operational pattern, of the mapping data t which the detected operational pattern .matches- with the highest likelihood- For instance, when deternnning the match, the- control system may determine a- state of the environment and or of the UAV during which the operational pattern is detected, and may use: ihe stale of the envi nment and/or of the OAY as as additional weighted iaetof for deiennining the matching operational pattern. In this way,, once the control system determines die matching Operational pattern using the the probabilit analysis, the control system may men. determi e the motor response proees based on the mapping data. Other cases and examples are also possible.

|Θ255| In a system arranged as described aboye, the motor response- proeess may involve various motor response operations, some of which are described below, la practice, the control system may determine the motor response proeess to ineSnde a single such motor response operation, or an feasible ^' combination of these motor response operations. Assumin two- o more motor response operations are: determined to be carried owt, determining the motor msponse process may also involve determining an order for carrying out motor response operations (e,g. _s with some motor response operations possibly being repeated at various points throughout the order) and/or a respective duration for applying each motor response operation* among ether possibilities. Generally ,.s«eh an order md/or durations ay be determined based on various factors, such as based on. the detected operational pattern of the motor for instance. Alternatively, such an order aud or dra¾tions may be predetermined in accordance with established mapping data,

}02S6| in either ease, various possible motor response operations arc described below. Although certain motor response operations are descr bed,, other Motor response operations are possible as well without departing front tte scope :tf the present disclosure.

|0:257| ia one example, a motor response operation may involve a particular ^• countering operatioa that counters unwinding of the fcj&er-due to at least one external force applied to the tether. As part of such art operation, the control system may operate the .motor to apply o e or more particular counteracting tor aes that each coniifeFaet rewin i g of the tether, sod possibly appl each eoimieraeting to!tjt!e or a respective duration. SpeeiScaily, each sneh counteracting torque may be at a magnitude that is substantially the same as the external foree(s) being applied and may he in a direction that, is effectively opposite to direction la which external ihree(s are applied- In this wa , this response operation may resist unwinding of the tether due to the external fbree(s) being applied without necessarily causing retraction of the tether back to the tJA¥. _: In practice, a tiser applying an external force to the tether tnay essentiall feel that the tether cannot be lowered any farther. Moreover, as magnitude of such counteracting torques increases, the tension of the tether may oierease as we l.

02581 I» another c ntpie, a motor response operation may involve a- particular assistance operation that assists lutwm ing of the tether dne to at least one external force applied to the tether. As part of such an operation, tbe eontre-i system may operate the motor to apply one or more particular assistive torqnes that cash assist unwinding of the tether, and possibly apply each assistive torque for a respective duration. Specifically, each sucb assistive torque may be in a direction, thai is effectively that same to direction ia which ^■ external fbree(s) are applied, and may be of any feasible magnitude, ia ibis way, the assistive torques may be used in combination with the external force(s) being applied so as to furtber help unwaiding of tbe teth&r.. In practice, a riser applying an external force to the tether m y essentially feel, that manual unwinding of tbe tether has been, made easier due ΐό lesse resistance to the vsawindiag.

|Θ2591 In yet another example, a motor response operation may involve a particular retracting operation that retract the tether against at least one externa! force applied to tbe tetber. As part of such an operation, the control system may operate the motor to apply one or re particular retraehng tprqu.es tliat "each ret act e tetber against the external :fbree(s),, afid possibl apply each retracting torque for a respective duration. Specifically, each sucb

5? retracting tmq nray be at a magnitude that is larger than the e ternal foree(s) being applied and may be in a direction that is effectively opposite to direction in winch -external iorce(s) are applied. In this way, this response ^'■ operation may resist miwift ing of the tetherdue to the externa! fbxce(s) being applied and feet cause retraction, of the tether back to the UAY despit the external foreefs). In practice, a user applying as external force to the tettter ma essentially feel that the tether is pulling against the user to an extent that the tether retracts even a though the oser applies the: extenial force.

f026lf ,|n yet another example, a motor response operation may occur after application of an external force by a user rather than during application of an external force by a user.. For instance, a motor response operation may involve a tether nrnvernern operation that moves the tether i accordance with a partieuiar tether movement profile after the ^• external force is applied onto the tether. In practice, such a motor response operation ma allow for user ^■ feedback/interaction, so be carried out even when a user no longer physically internets with the tether.

[0-261 J in thi regard _s t e control system could detect an operational pattern .indicative of a partieuiar ttser interaction aM then determine a motor response process thai is to fo carried out afier the particular user interaction is eompiete. In particular, the control s stem m determine that: the particular user tateractipn. Is complete by detecting yet another operational -pattern of the motor that indicates s and/or may do this its oilier ways, In either -case _* once the control system determines that the particular user interaetiO is complete _* the control system could then carry out the determined motor response process that involves movement of the tother i accordance with a partietdar tether movement profile.

|0262| Generally, the particula tether movement profile may take v-arions forms and ma be based on the operational pattern ardicative of the user-interaction. For instance, the tether movement: profile may simply involve retraction of the tether back to the OAV ^' at a particular rate. In this instance, ..movement of the tether in. aeeordanee with this tether movement profile may occur based on detecting an operational pattern that is indicative of the aser pullin down on the tether several consecuti e- times. Other instances and examples are possible as well.

[026 { Figure 22 next illnstrates an example motor response process. As shown, the control system determines that the above-described particular user-interaction 2110 corresponds to motor response process 220(1 Specifically, the motor response -process 220 involves a countering operation that includes application of a countering torque. ¾at countering torque ma have a magnitude of "Ti" that is substantially the same as the magnitude ^' "Fi" of the downward force being applied by the user 2108. Also, that countering tonpe may be in a direction that is effectively opposite to the dkection of tie downward force feeing ap lied by the «ser 2108. As such, the control system may ultimately operate the motor of fee winch system 2106 to appl that eorrateting torque as the nser 2108 applies the down ard force onto the tether. Ofter examples are also possible.

Ope fifig the Motor in Accordance with the Deiermimd Motor Response

Process

J026 | As noted above _* once a motor response process i determined the control system may then operate the motor in ;sccordat¾ce with ike determined motor response process, specifically doing so by transmitting to the motor One or owe conrrhands that instruct the motor to carry out certain operations i line wife the response process. And as further noted above, .fee eoniro system do so dnring and/or a ter user-inieraetinn,, .d p nding -on the moto response process that has been determined. Moreover, the motor response process thai is carried out may lead to various outcomes is addition to the planned interaetiors eedfeaek with the ^' user.

{02$5f For example, the motet response process: may correspond to one or more target tension forces being; Kotiutered by die tether. Specifically, each target tension force may be one tha Is expected to fee experienced by the tether when the motor applies a. certain tcasjtte- in accordaaee with the motor response process. As such, the control system operating the motor in accordance with tire determined response process may cause one or more such target tension forces to be encountered by the . ^' tether:

2 J In other example, the motor response process may correspond to one or more target tether movement being encountered by the tether. Specifically,, each target tether movement may be one thai is expected to fee experienced by the- tether whe the- motor applies a certain, orque in accordance with the motor response process. As sneh, the control system: operating the motor i accordance with the determined response process may canse one or more such target tether movements to be encountered by the tether (e.g., a wave pulse travel isig through the teihert. Other exaropies are also possible.

J0267J Figure 23 next illustrates example motor response process in. which the control system operates the motor to control tension of the tether 2102 as the user 2108 grasps onto the tether 2102, such as daring the process of manually coupling a payfcad for instance, Assutning that the DAY 2i00 substantially maisitains its physical position in space while hovering, the control system may proportionally {e.g., linearly) increase he torque o the motor la a wording direction as a downward force provided by the user 2108 Increases, d vice versa, 1» this way, the tension, of ^' the tether 2102 amy increase as the user 2! S pulls the tether 210 tether down, and vice versa. Mttreover, the control sysfetn may be configured prop^tionally Increase the torque of the motor Bp to a maximam torque, thereby s teaiin the tension of the tether and ideally preventin the user 210:8. front prilling the UA V 2100 down o ards the grotirtd.

|0268| More specifically, at state 23t¾ of the motor response process, the control systan operates the motor to apply a torque havirsg a magnitude ^' *Τ ^* to counteract the magnitude "F Γ" of the force provided b the user 2108, thereby resulting, is a .first tension forc feeing encountered by the tether 2102. at state 2304 of the m to response process, the control system operates the motor to appl a torque having a roagratude that is larger than ^' "Ti ^": and do so to counteract the force magnitude "F2" that ¾ larger than "Ft", thereby resiiliing ¾ the tethe 2102 encountering :a second tension, foree that is large than the first tension force.- Finally, at state 2306 of the motor response process, the control system operates the motor to apply a torqas having a magnitude that is yet larger than "T2" and do so to eoriRteract the force magnitude "F3" that is yet larger than "F2", thereby resulting in the tether 2102 encountering a thi d tension, force that is yet larger t rj the secon tension force,

$20\ Figure 24 next iliastrates an example -motm response proeess m which the control systeai may operate the motor to vary the araonnt, aad possibly the direction, of the torqrie that is applied to die tether 2102 over lime, specifically doing so to etthaace tiser- experienee or for other reasons: For Instance, the control system may operate the motor to replicate the feel of detents or clicks as the user 2108 polls down on the tether 21.02, and<½ to provide vibrational feedback (e.g., wave pulse) via the tether 2102, among other possibilities.

| 27if Mor specifically, at state 2402 of the rnotor response process, the control systeai operates the nioior to appl at* assistive- terojae that h as a ajagnitnde " l" aad is in the same direction as the ibree provided b the user 2108, thereby assisting the user 2108 with, unwinding of the. tether 2102, Then, durin unwinding of the tether 2102 at state 2404 of the raotor fesporsse process, the control system operate the motor to apply a counteracting _: torque having a magnitude ^W T2' ^" to counteract the magnitude ^*4 F2" of the force provided by the user 2108, thereby resulting hi a feel of a ''detent" being experienced by the user 2108. Finally, at state 2406 of the motor response process, the control system again operates the motor to: apply an assistive torque, so as to eoatipne assisting the user 2108 with irnwinding of the tether 102. Specifically, this further assistive force is shown as havMg a aiagnirade "T3" and being rovided In the same direction as the force {hav ng magnitude *'F3") provided by ihe isserllOE.

j0271| Figure 23 next illustrates- an■ exalte- motor response process la which the control system interprets the user 21 OS's nlteraetien with the tether 2102 to determine that the user 2 iOS's intention is to cause the tlAV 2100 and/or tile motor of ike winch system 2106 to. carry out certain operations. Speefikally, at state 2502 of .he motor response process, the control system detects an operational pattern that indicates that the user 210S pulled down on the tether 2102 at feast three eouseeuti-ve times with a force substantially- having magnitude, of " T', ϋροη detecting sueh. gesture by the riser 2108, the control s stem ma interpret the gesture as a signal feat a paylosd has been properl -deco-np!ecl- from the payioad coupling apparatus 2104 and thus that he UAV 2100 may proceed with further flight to a target destination. Generally, to facilitate such gestures, users could he provided with a manual or the like listing the -various gestures ^' that are mterpretable by the disclosed system.

Θ272 Mote specifically,; as shown by state 2504 of the motor res onse process, the control sysiem responds to the gesture by carrying o«t a motor response process that, invokes operating the moto to apply a torque having a magtutu.de "12" for pirrposes of te&acting the tether .2 Ϊ62 back to the UA V 21CS Moreover, the control system does so once the user 2108 has completed interaction with the: tether 2102 and thus no longer applies external fb ceCs) to the tether 102. Finally, once the tether 30 has bee retracted, the UAV 2100 may then proceed with forward Sight to a target destination, as -shown- b state 2506. Other exatnp!es are possible as well,

v. Additional Fmllures of !Jser iMer tkm an ^' , F db k

0273| In a further aspect, the control system could consider other factors as _: basis tor determining a motor response process.. In practice, the control system may consider .such factors, in addition t or Instead of consideration of the detected operational pattern of the moto as described above. Moreover, the control system ma consider any feasible combination of these -factors, possibly giving some factors more weight compared to others, fi!274| .hi one ease, the control sysiem ma consider a state of the environment as basis for determining a motor response process. Specifically, the control system may receive, from one or more of the llAV's sensors {eg., image capt re device), sensor data representative of the UA ^' V's state of the - .environment, such as of obstacles near the UAV, among other possibilities. And the control systetn na men determine the motor response process based at least, on mat senso data. For example, if the control sysiem detects an obstacle within a threshold distance awa from the tether, the control system, may fesponsively select a motor response process in ^■■ which the tether encounters smaller target letter movements rather than larger target tether movements, thereb attempting to avoid colhsion with the obstacle,

hi ariOther ease, the control system may consider a UAV's state of flight as basis tor deteffitining a motor esponse process . Specifically,, the control system, may .receive,, fern a lig t management system (e.g,, onbo r tie liAV and/or external to the U ^' AV), flight dat representative of a state of flight of the UAY, which m y e the UAV's flight progress along a planned flight _. p ath, among other possibilities. And the control system may then detertftilie the motor response process teed at least oil that flight data. For example, if the control sy stem deterrmne that tlre ti AV's flight progress is sigBiflcsBt!y behiad a plaoiieil schedule along the flight path, the control system may responsively select a motor response process in which die motor begins retrtsehng the tether to a certain extent, so as to indicate to a user that that the UA V's flight progress is significantly behind the planned schedule. Other eases nd examples are possible as well.

p276J In yet a further aspect, the control system may carry out the disclosed method

1 00 conditioned upon a payloa (e.g,, the payload eoupJing apparatus and/or a Coupled payload) being at a payfoad, altitude at w ich user-interaction is expected. More specifically, the control s $«sm ma eteOTtne a payload altitude of the payload and ros mahe a determination that the payload altitude is one at which a user-interaction is expected. Once die eoss ^' tml system makes that determination, the control system ta&y then responsiveiy carry out the method ! »)0■ snch as when a «ser-iateraetioa is actually detected for nsta ce 0277 Generally, the control system ma use various techniques to determine the payload altitude. In one example, art altitude sensor may he coupled to the payload (e.g, _s to the psyload coupling apparatus) and the control sensor ma c ive rom the altitude sensor, altitude data indicative of the payload altitude. In another exam le, the control system may determine alt Kuwotni lersgtfs of the tether, such as by using techni ues described hereto for instance. Also, the control system may determine a flight altitude based on altitude data received from n -altitude, sensor of the AV, among other possibilities. Then, the control system may use the detemiined unwound tether length of the tether as well as the determined flight altitude as basis for determining the payload altitude, f or example, the control system, tnay s btract the detenmned unwound tether length of the tether (e,g. _s 5 feet) from the determined flight altitude {e.g., 11 feet ahove grouftd) s as to determine the payioacl altitude (eg,, 6 feet above ground). in another example, the control .s stem may determine the UAV response i a state of the UAV ¾ environment and/or based on the U AV's state of flight if the caatrol system determines that Ac tJAY's state of flight involves he ^' UA hovering over a first location oa the- gronttd and that the stale of the UAV's en vttDameot includes a user physically pointing to a second location on the ground., then the- UA response process may involve the DAY flying ia hover flight so as to end: up hoverin ove the second location, snels. a for purposes of deli vering a payload at the second location for iestance. Other eanmles and aspects are possible as well.

(028 3 it is rioted that the ahove-desef&ed featntes related to use loteracilpa fcedhaek are uotlmhtedto: a siiBsiioa in which the UAV is hovering and eonid be carried otit in various slteatioas- without departing om the scope of the present disclosure. For example, the various features may he earned out . in a situation m whic the UAV has landed on a ledge -. and the tether has ^' been at least partially unwound such . that th tether is suspended by the UAV over n edge of the ledge:. Othe exam les are possible as well.:

Post-Oelivery Tether C&atrel

A* Release VerifieatioH

0285| As noted ab ve, when UAV ^' loweis a payload to the ground b controlling motor ic UR«ti»d a tether coupled to the pay load, the control system of the UAV niay -monitor the current of the motor and/or fhe rotation of the spool to verily that the payload has reached the ground. he control s stem may then operate tiie motor to caus over-run of the tether by eontimnng to imwioJ: the tether fern the spool. Once the touchdown of the payload is verified and tether over-tun. is performed., the control system may operate i : a release- verification mode hi order to verify separation of the payload from the payload coupling apparatus, before beginning the process of lifting: the payload coupling apparatus hack, to the UAV.

fft286| Figure 26 is a flow chart illustrating a release verification method 3800, according to an ex mple enibodhment Method 26(30 may be hhtiated nporj the completion of method ! 8 0 e.g. _s at the end of the- tether over-ma period), as part of operation in the refease-verlfseatio mode:,

|028?f As shown, method 2600 involves the control system operating the motor in the irsi mode where torque Is applied to cotsnter the pull of gravity on the tether) for a release- verification period, as show by block 2602, In. practice, the control system ma appl a speed profile designed for release verification. T¾» Speed profile may be designed so as te lift flic specific weight of the payload coupling apparatus a small distance daring the release- ecupririg- apparatus, in which the tetfeer retracts fully to pull the payioad coupling apparatus id the UAV, and seat fie payle-ad coupling apparatus in the KV'i receptacle: for the flight back to a return location,

}03&3| More details regardin retraction of ike tether and payioad coupling apparatus after delivery are provided in reference to .Figures 38A-38G below.

XI -■ Oampiit g sciikiiou s of a Payioad

0294| .In practice, the UAV may sometimes encounter situations in -which the tether fe at least partially laiwound and a suspended payioad eeuple to the tether is susceptible to oscillations. I one example of tins sihsation, the UA V ma deploy the tether for delivery of a coisp!ed; payioad, thereby making the coupled: payioad susceptible to oscillations., fa another example of this situation, the UAV ma deploy die tether for picku of a paytoad _j . thereby making the payioad coupling apparatus (e,g, ₅ considered- to be the payioad in this case) siiscepiibie to oscillations. !« yet another example of tins situation, tise UAV may retract the tether following coupling of the payioad for pickup, thereby making the ^■ -coupled payioad susceptible to oscillations, in yet another example of this situation, the UAV may retract the tether fel!owui release, of the payioad alter delivery, thereby makin the payioad coupling apparatus (e.g., again considered to. be the payioad in this ease) susceptible to oscillations: Other examples are also possible,

}&295f in such -situations, various factors rim cause oscillations of the suspended payioad. I» one example, su eten strong wind conditions ma cause the payioad to oscillate. In ^■ another example, movement of the UAV to maintain Its position; in hover mode may cause the payioad to oscillate. And. in yet another example, oscillations of the payioad may be a result of an external foree applied b a user to the iether and/or the payioad itself. Other examples are also possible.

ffl296| Oenerally, oscillation of the payioad .may cause the payioad to move hack and forth hi a peudnium4ike motion, also referred to as peftdular motion, in praetiee, the pendular motion of an esc dialin payioad could have- various eousequeriees. For example, the peudnlar motion of an oscillating payioad may have undesirable effects on the stability of the UAV, may create difficulties is positioning the payioad in a desired location on the grotrfid, may create an. undesired movement of the payioad near the ground, or may create difficulties in seating the payioad coupling apparatus in the OA V¾ receptacle, among other problems, f0297 fo resolve these ^■ ■problems,- the UAV- g control, system may perform one or more dapping techniques, such a those described, below. As noted above, such damping techniques may be pert¾rtne _; d after delivery of the payioad, during a pause in the tether retraction process. Ho ever, ft should be rtderstood that the below described daaipin techniques could ^' be applied iu otter : scenarios as well, Further, damping tecMipes- described rterem ^■ could be applied In scenarios where the pay load is still attached to the payload coupling apparatus (perhaps with sorne adjustments to account for the increased weight suspended froui the tether, as compared to when only the pay load coupling apparatus is attached).. More generally, datnping iechmques disclosed herein could apply in any scenario here a tether suspends a weight from an aerial vehicle,

A, Dei eefioa and Evduati * of Payioad Oscillations

0298| in an. exam le, inn^lementation, a IJAV ^" play include one o toore sensor arranged to generate sensor data indicative _: ¾f oscillations of the payload eoppling apparatus (and/or of the coupled payload) suspended belo the UAV. In practice, these sensors may include a current sensor coupled t the winch motor,, a tension sensor oft die tether, an inertial rneasurernent unit (IMU) on the UAV and/or on the payload coupling apparatus., s image capture device on the UAV, ahd o an encoder on the winch tnoto , smoiig oihef possibilities. Accordingly, the UAV's control system may use sensor dat froni any combination of such, sensors so as^io-detec ^' oscillations of e.j>aylaa .:as well as attribates of the oscillations, such as amplitude, jrequeney;, and/or speed of oscillations, among other options.

1&2 In one ease _* the current sensor may generate data represcuiaiive of electric : current characteristics of the motor. The control system may receive such current data and may use the current data as. basis for detecting oscillations of die payload us well as: for determining anrifrates of those detected oscillations. To do so, the control system could refer to mapping data or the like that maps various current characteristics each with an indication of payload oscillations arsd/or with respective attribute, of payload oscillations. For example, a particular set of current characteristics (e.g., a pariicttlar reiative change in current value) may be mapped to an indication that the pa load. is oscillating. Also, another particular set. of current characteristics (e.g., a particular rate of change in current value) may be mapped to n indication that the payload is oscillating with a particular amplitude of oscillation.

|03(K)f in another case, the tension sensor may generate tension data representative of tension of the tether. The control system may receive such tension data and ma use the tension data as basis for detecting oscillations of the payload as well as for detsmiiuing attribute* -of those detected oscillations. To do so, the control system could refer to mapping data or the like that maps various tether tension characteristics each it an indication of payload oscillations and/or with respective atirihuies of payload oscillations For example, a particular set of tether tension cii racieristics (e.g.„ a particular relative change in tension) may be mapped to an indication that .the payload- is oscillating. Also, aaotherparticular set of tether teasi tt characteristics -{e.g., a particular ate of change fa tensibrr) may be mapped to an indication that the pay load is oscillating with a par if eular speed,

}CBotJ in yet another case, the !MU may generate movement data Indicative of movement of fee -pay-load relati e to the aerial vehicle. The control s stem may recei ve such movement data and may use the movement data as basis for detecting, oscillates of the payload as well as for determinirfg attributes of feose detected oscillations. To do so, the eoshrol system, could refer mapping data or the like that maps varioiss characteristics of movement data each wife, m indica ion of payload oscillations aftd or with respective attributes of payload oscillations, for example, a particular set of movement: data characteristics may be mapped to an indication that fee payload is oscillating. Also, another particular set of movement data characteristics Movement data indicative of particular force) may he mapped to as indication that: die payload i -oscillating w th a particular amplitude of oscillation,

f03t2j !n yet another esse, the image capture device may fee arranged to face the payload and thus provide im ge data representative of position of the payload relative to the I .V. Witli this arrangement, the control system .may receive the image data and ma use any currently town -and/or future developed image rocess n techniques to e aluate the tnaage data, In doing so, the control sy stem may use the image data to determine: position of the payload over lime. Mote specifically, the control syste may detect oscillation of fee payload by determining a difference in . ^' position- of the payload over time. Moreover, the ^• control system could use the image data as basis for determining attributes of detected oscillations,. For example,, the control system ma determine a difference between certain payload positions over time and then determine amplitude of oscillation based on the determined difference. In. another example, the control system may use the image data to determine a rate of change in position of the payload and then determine a speed of oscillation based on the detennined rate of change. Oilier eases and examples are possible as well.

|Θ303| Moreover, various attributes of payload oscillations ma depend on the extent to which fee tether is unwound. For ^■ instance, a shorter unwound tether length may cause the payload to swing with a higher- freq enc compared to a frequency - with. which the payload swings when the unwound tether length: is longer. For this reason, the control system may consider u wou d: tether length as am additional factor when determining, attributes of payloa oscillations. For example, after deteonming that the tether is unwound at a particular fength, _; the eontel system ay determine jpositi fts -of the payioad: over time. Then :the control system ma relet to ma ing data thai maps the combination ike determined unwound length of the tether an the determiised positions to a particular smplliede of oscillation ami to particular ftequeftcy of oscillations. AlietBatively.. the control system may determiae sttch attributes based oil a predetsnnined formula ^' that inputs variables, such the unwound tether .length and determined positions, a»d that■ outputs data indicative of o.se or more of tbfe abo ve-n eiiti oned atehutes. Other examples are also possible.

|03i | ,|«. practice, t e control system, may dete mine the unwound tether length fey recei in ffpth the encoder position dat representative of the unwound length, of the tether. More speeiSc8ily,:ike encoder .aiay he coispled to the inotorsuch th t as the motor carries out rotation to unwind asd or wind the tether, the enc d r generated data rep-eseiiiauve of an angular position and/Or motion of the motor (e.g., of a tra:iisiuis a.n asseiBbly of the motor). As such, the control system may receive the data and may use the data as basis for tracking tht- unwound length of the tether< For example, the control system may detec two revolutions of the motor in particular dheetien based on the data from the encoder and may determine that those two te voMj ns correspond to uswfeding of the t her b two rasters; Other e amples are als possible.

jlB0S| In a t rtlier aspect, the control system, rosy also use the sensor data as basis for determining the detected oscillations exceed a threshold (e. _; g., established via uiao.ual engineering input). For ex sgfe _t the control system may determine that the sensor data is indicative of a particular amplitude of die oscillations of the payload, and may determine thai the pariieular amplitude is higher than threshold, amplitude. In another example, the control system that die sensor data is indicative of a particular speed of the oseiltaifcnis of die payload, .such as a speed at which the payload swings hack a»d forth while the tethe is partially unwound; n this example, the control system, may then determine that this particular speed is biglier than a threshold speed, in yet another example, the control system that the sensor data is rodieatsve of a particular frequenc of the oscillations of the payload, such as a fequene a which the payload swings back and forth while the te her is partially unwound, in this example, the control, system, may then determine that this particular ftet eney is higher than a threshold: frequency. Other examples are possihie as well

1. aiHjjiiig ditrt&g a ^' fe her Retraction Process

{$306j Figure 2? is flowchart illustrating a method 27¾ for initiating dampin routine (could also he referred to herein as a damping i^hni ue ., aeeordhig to an example embodiment Method ^' 27-00 may be implemented b a UAV's eoutrol system during a tedier retraction process, la practice, the tether retraction process may be carded out after delivery and/or at -other times during pick-up and/or delivery, Moreover, -although method 270(i is described as being, carried oat its the context of a pa load coupling apparatus, method 2700 could also b earned out m the context of a pay-load coupled to the payioad coupling apparatus.

307I Turning to method 270¾, the tiAV m y autlaUy be -operating in a hover flight mode, as shown by block ^' 270-2. For instance _* the OA V may hover over a target or delivery location, or over a source location. Once the payioad is released on the ground, the UAV's control system may switc to a tether retxacdOft mode, as shown by block 2702. ^' hile operating, in. the -tether -re traction Mod , the control system may perform a damping routine to dampen the oscillations of the payioad coupling apparatus, as shown by block 2794. Optionally., ie control system may do so specifically in response to determining that deiected oscillations exceed a tin¾sho!d,

p308| Gene lly, the damping routtoe that the control system performs ^' may be any eombinatiori of ^' the damping routines described herein. In some cases, however, die control system may perform one o more dasnping -.mutiae other thos desc ibed herein & da so ^• without- departing frorn the scope of method 2700,

f #399 f As noted, a ove, a dam ing reumrfc, such as that perifernjed. at block 2 04, may be carried out du ing panse in the ascent process {and perhaps durin a pause while lowering the payioad coupling apparatus as well). In some embodiments, die control system may wait u til di oscillations are sufficien ly dampened before .resuming- the process of retracting (or lowering) the tethe _* For example, die control system may pause until it determines that the ampiitode of the oscillations is less than a threshold amplitude, or possibly even mat the payioad eonpHng: a paratus i resting In an eq«iKbrittm position. In either ease, the control system way responsive ^' ly .resimie retraction of the tether to. lift the payioad coupling -apparatus to the UAV. In o ther embodiments, however, the control system atay not wait utttiS the oscillations are sufficiently darnpeti before resuming the process of retracting (or lowering) die tetter, Bor example, the control system might pause the tether retraction process for a fixed period of time before resuming. Specifically, upon starting performance of the damping routine, the control system may initiate a timer that is arranged to expire after a particular duration (e.g., established via manual engineering input), and may resume the- _. rocess- of retracting for lowering- the tether in response to detecting expiration of that timer. Other examples are/also possible; {0310} Figures 28A to 28D next collectively iliBstrate initiation of a dattjpiog ro ittne during a tetter Mtaetion poeess.

As shown b figure 28A, a !JAV 28(50 includes tether 2802 and a payload coupling apparatus 2804 coupled to -the tether 2802, Also, a payload 2806 is sliowii as havi»g been delivered by the 13AV 2860 at a delivery kieation. on the grotmd. Moreover, Figure 2.8A .shows that the UAV 281)0 Is hovering over the delivery location while the ^' ;0AV ^* s control system operates m the tether rep-action mode to ascent the payload coupling apparatus 2804 bad t o the UAV a ter delivery of the payload 2806.

{03J2J As shown by Figure 28B, while operating in the tether retraction p¾> e, ..the

I ⁾ AV's control system pauses the ascent of the paytdad. eoypimg apparatus 3804.. t ⁾ uri»g the panse, the control system perlbmis a damping; routine, as indicated b Figure 28B,. As noted., the damping routine could be arr of the damping routines described herein, among others. Optionally,, as noted, the control system performs the damping routine m response to defecting that oscillations of the payload coupling apparatus 2804 ar¾ at an oscMiailon amplitude 2808 tnai is gieater than a threshold, amplitude.

{0313! As shown by Figure 2&C, while the tJ Vs control system still pauses ascent of r½ payload couplin apparatus 2804, the oscillations are shows to have bees dampened due to the dampin rotrtin©-, to. om case, du ing the pause and after carrying; out of the damping routine for some time period, the control system detects that oscillations of the payload coupling appaiiites 2804 are at: an oscillation a plitade 2810 that is lower than the threshold am linide- la tin ^' s way, the control system determines that the oscillations have beet! sufficiently dampened an responsivehy determines that the tether retraction process may resume. In another ease, the co!itroi system detects expiration of a timer initiated upon starting performance of the damping routine, and determines that the tetSier retraction process may resnme In response to detecting expiration of that timer _* As such, in either ease, the control system may resportsivety resume operation in the teifcer retraction mode to ascent the payload coupling apparatus 2804 back t the UAV 2800 after delivery of the payload, as shown by Fignre Other iilustrations are also possible.

C, Example Ba ping Tecisiiimies

{03141 AltSiongh several damping teehrti< ues are described below, it should, be understood that other damping teehtiiqa.es and modifications to the described t€clffif¾ues are possi ble as well withont departing from the scope of th present disclosure,

1 Forward fiigkt to iJampm Omslfctii (Θ315| Figure 29 is a flowchart iliastradng & metho 29W for ini fetin forward flight to dampers oscillations. As noted above, the OAV may be configured to. f y fa accordance with a hover Sight mode and in accordance wit a forward flight mode, & hover flight m de, flight dynamics may be similar to a helicopter. More specifically, lift and thrust may be supplied b rotors that allow the UAV to take off arid land vertically and fly in all directions, in for ard- tight mode, however, flight d namics may be similar to a n airplane. More specifically _* a fixed-wing: UAV ma be propelled, forward by thrust from a jet engine or 8 propeller, with fixed wings of the UAV providin liftin and allowing the WAV to glide substantially iiorixontaMy relative to me grontid.

($31$} With, this arr ngements the OAV ma operate ia accordance with hover flight mode, as sh n by Mock 2902.. As noted, the UAV aw do so dtning a process of deploying tire tether for payload pickup and/or for payload dehVery, or may do so during a p ocess of retracting the tether for payload pieknn and/or for paytoad delivery. Regardless, white di UAV is its the hover Sight mode,, the DAVs control system may cause the UAV to switch ftoro the hover flight mode to the forward flight taode, as sh wn by block 2904.

(0317j Optionally, the control system may do so is response to deternnning that detected osci lations exceed a dueshold. Als , die payload at issue may fee considered to be a payload (e.g., a package) that is couple the payload coupling apparatus or s¾y be considered to b the payload coupling apparatus itself, aniong od¾er possibilities.

|0318 Mote specifically, by switehat t die forwar d flight mode, the movement of the UAV ma re-salt in drag on the payload. Generally, drag Is considered ^' to he m aerodynamic force or friction that opposes or resists an object ^' motion through, the air due to interaction between the object and tnoleen!es of the air. So in forward flight scettari©,. airflow may result i» drag that is directed along direction opposite to the direction of lite forward flight. Thus, the resulting drag ma dampen the detected oscillations of the payload because the airflow may Kelp stabiiixe the payload.

f031i>f FurtheraKse, in, some embodiments, whea the control system causes the ll ^' AV to switch, to the forward flight mode, the control system may aiso direct the UAV to operate in the forward flight mode with: certain flight characteristics, In. practice, these flight, characteristic ma htolade flight speed, flight direction, and/or flight iimiBg _s among other possibilities. As such, the control system may determine the appropriate flight characteristics based OK various factors. And. in accordance wit the present disclosure,: the control system .may determine the appropriate flight characteristics eased at least on the detected oscillations of the payload aad or base on other factors. [0320} By svtsv of example, she control system may dei&nttinc an initial flight speed for the. forward flight mode based at least oti the detected oscillations. In practice, the initial flight speed may be a flight speed to which die 13ΑΎ initially accelerates imediaiely after S¾'itcliing to forward flight mode and one which the UAV ultimately aiahltaias for at least .s me time period dorms the forward flight mode. So in. accordance, with die preseat disclosure, the control system may determine an initial ^' flight speed that is generally higher when amplitude of the detected oscillations is greater _* For instance,, the control system ma select a first initial flight speed when the control system detects a first amplitude of oscillation of the payload and may select a second initial fli ght speed h the control system detects a second amplitude of oscillation of the payload, with the f irst amplitude being higher than the second. ^: ampl tude a»d die first initial flight speed feeing higher than th secoad initial flight speed,. Note that the initial, flight speed aiay additionally or alternatively depend on mass, and/or drag of the payload, or may simply be predefined: via. manual engineering input or the like

|032iJ In: another exa le, the control, system ruay determine Sight tiaiia for the forward flight ode based at least on the detected oscillations, in particular, deteitnining flight tht n niay involve determhhn a time a which to initiate the forward flight mo e, a duration for whic to carry oot damping as part of the forward light mode* and/or & time to end the forward: flight mode, among oilier possibilities, In either ease, the control system ma consider yarieas factors: related to ihe detected oscillations as basis, lor detertthni g the flight timing. m~ instance, the control system may determine state of the payload: swing, swell as whether the payload. is at top of a swing of a bottom of a swing, and. use that determined state of the payiead swing as basis .far determaiing the flight timiag. !a another instance, the control system may determine an extent (e.g, ₅ amplitude) of payload oscillations and may determine the flight timing based, on the detenslned ^' extent. Note that the flight timing may alternatively be predefined via manual engineering input or the like. Other instances and examples: are possible as welt

f0322f M a further aspect, the eontrol system may help facilitate e forward flight: damping raniine in varions siteaiioes. In one example situation, the control system ma initiate forward flight to daaipen oscillations during a process of retracting the tether for payload pickup and/or for payload delivery. In this example situation, the coritol system could technically initiate the forward flight at any point of the retraction process, such as without a pptse. n the retraction: process... ideally, iiowever, the control system: may operate the motor to pause retraction of ie tether while the detected oscillations exceed the threshold, which may allow the control system to initiate the forward light mode during; :the pause m the reiiaetiiwi process. Then, once the: control system detects that oscillations of the payload tee been sufficiently dampened by die drag (e.g., that the detected oscillations no longer exceed the threslioid) atid/o after a fixed time delay (e.g., in response to delecting expiratio of a timer), the control system may then operate the m to to resttme retraction of the tether,

0323 In another example siteatioti, the control system may initiate forward flight to dampen: oscillations during a process of deploying die tether for payload picknp and/or for payload delivery. Irs this example situation, the control system eoui teehineali initiate the forward flight at any point of the deployment process, such as without a pause In th deployrnent process. Ideally, however _* tile coot system may operate the motor to panse deployment of the tether while the detected oscillations exceed the threshold, winch may allow the control system to initiate the forward ^' Sight mode dntifig the pause in the deployment process. Then, once the control system detects that osciiiatiotis of tl¾e payload have been snffieientiy dampened by the drag and/or after a fixed time del y (e.g.. In response to detecting expiration of a thner), the control system may the operate the ot r to ressrrne deployment of the tether .. Various other example situations are possible as well.

| 324| Yet fnrthet, when the control system operates the motor to resume deploytnent or retraction of die tether, the control system ma ideall do so while the 0AV operates in the forward flight mode, htrt could also do so while the UAV operates, in the hover flight mode, £6325! example, once the control system detects thai oscillations Of the payload have beers snffieientiy dampened by the drag and¼ after a fixed time delay, the control system may responsively operate the motor to deploy or retract the tether as the control system also causes: the ^' UAV to eoatinae operating in the forward flight mode. Also, in .the context of retraction for instance, the control system may direct the UAV to maintain a particular for rd: flight speed (e.g., tire determined initial, flight speed) as the tether is being retracted- In this way, die control system: ma ensure safe arsd steady retraction of the tether. Then, once the control system determines thai that tether retraction is complete, die control system ma then responsivel change :(e.g. _S; increase) the forward flight speed, if applicable, {0326| Additionally or alternatively, ones the ietfier has heen. fully retracted, tile control system eonld then cause the UAV to switch: from, the forward flight mode back to the hoyer flight mode, hi this f«gard _: , after the UAV switches tmck t the hover fight mode, t e control system may then operate the motor to deploy the tether, hi this way, the .forward flight may dampen oscillations of the payload and subsequent hover Sight may allow for tether deployoient Over a particular location, such as tor payload pickup o delivery purposes. Other examples are possible as well,

_. {0327} 1» a farther aspect, _. :¾se:c0at ol system may carry ott method 2900 conditione upon the payload being at a safe dis ianee a way from the tlAV. Gesierally _> th control system tffiiy do so to ensure that the payload does not collide with ike UAV upon initiation of forward flight and/or may do so for oi er reasons. Nonetheless, the control system- may do. so iu various ways. For ex m le. the con ol system may deteimiBe the unw und length of ^' the teiher and may then determine that the unwound length of the tether is higher than a threshold iengih, thereby irsdlcaiiug to the eoutml system thai the ay!oadis at a relatively safe distance away from .the UAV:, in this way, if the control system seeks to carry Out method 2900, the coutrol system may o so ott!y if the control, system ileterraines thai the imwouud leiigth of the tether is higher than the threshold length. Other examples are also possible,

|9328J Figures 30A to 30D collectively illustrate the technique fnvolvi«g towar flight to danipeu oscillations _* speeiScally doing so dttrirtg a -tether retraction process,

(G329J ^' As showu by Figure 30 A _s . a UAV 3000: ineksdes tether 3002 and a payload coupling apparatus: 3004 coupled: to the tether 3002. Also, a payload 3006 is shown as haying beeti delivered by the UAV 3000 at a delivery !o£afio» -eft the ground.. Moreover, Figure MA. shows tliat the UAV 3000 is hovering o er the delivery location while the I) A.Y's control system operates in the tether retraction mode to ascent the payload coupling: apparatos 3004 back to the UAV after delivery of the payload 3006.

|CB30| As shown by Figure 308, while the UAV 3000 is in hover .flight mode, the

UAV's control system pauses the ascent of the payload coupling apparatus 3004. Duris the pause., the control system may optionally detect that art trnwoand length 3010 of the tether 3002 is greater thaa a threshold length. Also, the -control system may optionally detect that the oscillations of the payload coiiplfeg apparatus 3004 are at an oscillation amplitude 3008 that is greater than threshold arnplitude. In this regard, the control system may then responsively peribrms the -forward Sight dampin routine, as shown by Figure 30C, hi particular, white the UAV's control system still pauses: sscent of the payload couplin apparatus 3004, die DAV 300 responsiyely switches from operating i hover flight mode to operating Iu forward Sight mode, in other cases however,, the control system ma not detect oscillations and may simply carry out the forward flight damping routing for a fixed period of time (e.g., until detecting expiration of a timer),

}ίϊ3 | As shown, fey Figure 30C, b switching to the forward flight, mode, the movement of the UAV 3000 results to drag on the payload coupling apparatus 3004, which dampens the oscillations of the pay load coupl&i apparatus 3004. Accordingly, during tfete pause and after the UAV carries out for ard flight lor some time .period, the control system detects that oscillations of the payload coupling apparatus 3004 are at a oscillation amplitude 3012 that is lower than the threshold amplitude... In this way, the control system detetmmes that the oscillations have been sufficiently dampened and respoftsively detefmitj s that the tether retraction process may resume.

{033f| As s ow , fey Figure 30|¾ in response to determining tliat the oscillations have bee sufficiently dampened and/or in response to detecting -gyrat on -of :ai tnef. _t .--&e control system. the resumes operation in t e tethe retraction mode to ascent the payload coupling apparatus 3004 back to the U AV 3000 after delivery of tie payload. Moreover, the control .system is shown, to resume operation in the tether retraction mode as the control system continues directing the UA 3000 to operate in forward flight mode. Other illustrations are also possible..

it RMming. an Bximt of Flight Si bUizatkm to Dampen O iilaimm

|Θ333| In accordance with an example implementation, the UAV may be operable i posiiion*ho mode in which the UA substantially maintains a physical position is ph steal space during hover fhght. Generally, the UAV may do so b engaging in one or more Sight stabilization techniques (eg., vision- based sta¾iji¾siioB and/or IMU-based stafeifizatioti) dnring Ijover flight, such as- stabiliza ion techniques thai are cwrently know and/or those developed in the insure.

|<3334f Specifically, the UAV ^' mm engage in flight stab lization along three dimensions in physical, space, so as to resist movement of the UAV along arty one of those three dimensions and. thus to help maintain, the UAV's physical position. In practice, the three . dimensions at issue may he the yaw axis of the UAV, the pitch axis of the UAV, and the roll axis of the UAV÷ Additionally or alternatively, the three dimensions may include any feasible tra s!ational axis for the UAV (e.g., any axis along which rranslational movement of the UAV is possible). Bui the three dimensions could also take o» various other fortPs without departing fern: the scope of the present disclosure,

[03351 Fignre. 31 i a flowchar illustrating a method 3100 for redneing an extent

(e.g,, gains) of flight st b lization to dampen oscillations f'go limp" damping technique?. As shown by block 3102 of method 3100, the UA V may operate In the posilion-riok! mode. Here again, the UAV may do so d ring a process of deploying the tether for payloa picktt and or for payload delivery, or may do so during process of retracting the tether for payjoad pickup atid o for payload delivery. Regardless, while- the fJAV is in the position-hold m de;, the along a particular axis 5» each direetio.n rattier than the UAV attempting to maintain tire UAV's phf steal Qsiii by resisting any movement of the UAV away from that physical

}034O| Moreover, the cont ol system slay consider v?tdo¾s ftctors when determinin the extent to which to reduce stabilization along the at least one daBension. In m example implementation, the control, system may use the detected oscillations as basis for determining •a target extern: of stabilization, in doing so,, the control system ma deiemiiae a lesser target extent of stabilization when the amplitude of the detected oscillations is greater, thereby allowing for greater movetnent of the ¾V along the at least one diiviensiou so as to help dissipate energy. An due to swell greater movement of the UAV, the _. higher amplitude oscillations may ultimately dampen. Othe eases and examples are also possible,

f 03411 Following redaction of flight stabilization along the at least one dimension, the control sys em -may detect that oscillations of the paytoad have been sufficiently dampened and/or may detect expiratioa of a tinier initiated at the start of die "g limp* ^' d m n tontine;}, and may responsively eanse the aerial vehicle to increase an extent of flight stabilization along the at least one dimeasioa. In accordance with the present disetosure, such increase of flight stabilization coo take on various forms.

j#342 In one €xam .fe _s assuming tliat: the control system cansed the UAV to completely eliminate any form of siahilkation: along ibat dimension, the control system may cause the DAY to completely activate stabilisation along that dimension as an attempt to ty maintain the UAV's physical position la another exam le:, again assuming that the contr l system caused, the UAV to completely eliminate any form- of stabilkatio along that dimension, the control system may cause the U AV to increase art extent of stabilization along that dimension by effectivel allowing some range of movement, of the UAV along the at least one dimension relative to die physical position. In yet another example, assuming that the control system caused the UAV to partially reduce Ae extent of stabilization aion the at least one danensioa, the ^' control system may -cause the UAV to increase the extent of stabilization along that dimension, in this example, the control system may cause the V io increase the extent of siBbihzation (e,g., to the ane extent prior t the reduction), s as to effectively lessen the allowed range of movement of the UAV along the a least one dimension relative to the physical ..position. Alternatively, the control system tnay canse tie U V to increase the extent of stahiikation so as to completely activate stabilization alon that dimension in an attempt io fully maintain, the 1IA.V'$ physical position,. Various other examples are possible as well. (Q343 In 8 further aspect, the coatroJ system may help facilitate t!ie " o limp" damping iecliai we in various situations. 1ft one example str iiom, the control system may ^' Imitate the "go limp" damping technique during a process of retractiog tfce tether for payioad pickup antl/όί for payioad delivery, lit ibis example situation-, the control system, co« teehnicaliy initiate the " o limp" damping teehnirue at any point of the retraction process, .such as witbout a pause in. the retraction process. Ideally, however, the control system may operate the motor to pause retraedon of the tether while the detected oscillations exceed the threshold, which may allow th control, system to initiate the '"go Im '' ¹ daraptftg technique during the pause in the reiraetion process, Thea, once the control system detects that Oscillations of the payloas! ave Been sufficiently dampened Mo i g reduct ion in the extent of flight stabiiizatio along at least one dimension (e.g., . thai the detected oscillations no longer exceed the mreshold) and/or after a feed time delay (e.g,, upon detecting expiration of a timer), the control system may then operate the motor to resume retraction f the tether.

344| In another example sitwation^ the control system may initiate the "go hmp" damping technique during a process of deploying the tether iior payioad pickup and/or for payioad delivery, in this example situation, the eostrol system could technically initiate the "go Ihryf ' damping technique at any point of the deployment process, such as .it¾oet a pause in the deployment process. Ideally, however, the control system »¾ay operate the motor to pause deployment of the tether while the detected oscillations: exceed the threshold, which may allow the control system to initiate the "go liPip" damping technique duriag the pause in the deploymeBt process: Then, once she control system detects that osc illation of the payioad have been stifficiertlly dampened following reduction is the extent of flight sta izaiiors along at least one dimensio and/or after a fixed time delay (e.g., upon detecting expiration of a timer), the control system may then operate the motor to resume deployment of the tether , Various other ex m le .situations are possible as well

f 0345J Yet feather, when the control system operates the motor t resume deployment or retraction of flic tether, the control system may do so while the flight siabili^ahon along the at least one dimension is still reduced aad br after flight .stabilization; along at least one dimension has been increased. For example,, os.ee the control, system defects that aseillaiions: of the payioad have beea suffieiently dampened, and or delects expiration, of a timer, the control system may responsively operate the motor ic deplo or retract the tetiier as the control system also causes the U A V to maintain reduction in the extent of flight staMhzatiofi along the at least oae dimension. In aaother example,, once the control sysfern deteets f iat oscillations of the payioad have hecn snfi!cieatly dampened and/or detects expiration of a timer, the control system may _; respOttSively cause the UAV to increase the extent of flight stabilisation along th at least one dimension. In this example, after the UAV increases the ■•extent of Sight stabilization -a!oag the at least .one dhneosion, the control system may then operate the motor to deploy or retract the tether, Other examples are possiMe as well |034o| Figures 32A, to 32H next, collectively ilSas rate the "go. limp" damping technique, specifically heing carried o«t during a tether reir action process,

347| As she n: by Figure 32A _S: a - ^' UAV ^' 3208 includes tether 3202 d a payioad coupling, apparatas 32Θ4 coupled to the tethe? 3202. Also, a payioad 3206 is shewn as havin beer? deli vered b the UA V 3200 at ft delivery location on the ground,. Moreover, Figure 32 shows: that: the U ^' AV 3200 is hovering oyer the delivery location while the UAVs control system operates hi the tether retraction mode to ascent the payioad coupling apparatus 3204 hack to the UAV after delivery of the payioad 3206. IB this regar l, the UAV 3200 is shown as being in a position-held mode in which the UAV 3200 substantially maintains a physical positioti is physical space daring hover flight

0348| As shown, by Figure 32B _S while operatin in. the tether refraction mode, the

UAV's eoBtrol system panses the ascent, of the payioad. eouplhig apparatus 32Θ4. Baring the pause, the control system optionally detects that oscillations of the- payioad coupling apparatus.3:204 are at an oscillation- amplitude 208 that is greater than a threshold amplitude,, fesponsive to detecting oscillations in this manner and or respoasive to u tiating a timer, the control system then perforins the above-described " o limp- ' damping routine, lit partieBlar, the control system causes the OA.V to reduce an extent of flight stabilisation along at least one ih ension. By doing so, the UAV then .rnoves along that dimension based on application ^• of external forces to the UAV, which, may dampen oscillations due to energ dissipation;. Sisch nrovement and energy dissipation k illustrated by Figures 32C to 32F.

f03 f More specifically, due to reduction in the extent of flight stabilisatio along the dimension, the swinging payioad couplin - apparatus 3204 drags tire UAV 3200 in a first direction along the dimension to a position that is at a distance Dl away from position *' A"\ as shown by Figure 32C. Subsequently,, disc to continued redaction Ire the extent of flight, stabilization along- -the- dn¾eiision and due to. energy dissipation,, the swinging payioad coupling apparatus 3204 drags the UAV 3200 in a second direction (e,g„ opposite to the first direction) alon the dimension to a position that is at lesser distance 02 (e.g., smaller than Dl) awa from the physical position '%:Y ^* as shown by Figure 32D:. Sybse entry, again due. to eontinned redttctiors in tne extent of flight stabilization along the dnrieiision and dee to turther energy dissipation, the swinging payioad eonpling apparatus 3204 drags the UAV

SO

amplitude 32,10 tisat is: lower than the threshold .amplitude. Itt practice, the control system may carry out. such detection while flight, stabilization, is still reduced, along ihe dimension and/or after the control system increased flight siabilizatiort along the; dimension. Nonetheless, the control systern determines that the oscillations have been sviffieienily dampened and/or detects expiration of a: timet, and iesponslvely determine thai the ctfeer retraction process resume. As such,, the control s stem may responsively restnne ope tion in the tether retraction mode to ascent the payload coopling apparatus 3204 back to the DAY 3200 after delivery of the payload, as show by Figure 32H, Other libe ti n are also possible;

M Umvinciing/Wimttftg Tether ϊϋ Detypm (Mciikiiiam

|θ35ί In accordance with example implementation, the OAVs control system, may dampen oscillations of the payload by operating the motor to unwind aad or wmd the tether, thereby changing tension on the tether. In doing so, the control, system, may increase andlor decrease th nnwonnd tether length and do s at various rates, winch may help dissipate energ and thus ultimately dampen the oscillations of the pay toad, in this manner, the control system is provided with. a additional control input tha does not necessarily Interfere with the other control objectives of the system. Ce,g< _; . does iot prevent the vehicle from holding position wliile aiso damping payload oscillations},

|Θ352 More specifically,, the control system may operate the motor to vary a retraction rate of the tether and/or a deployment rate of the tether, in practice, the retraction rate may define timing, extent, «n ?r. speed of tether ret ctio and the deployment rate may define timing, extent, and/or speed of tedier deployment. As such, the control s tem may may operate iise aioir in the first mode to retract Ihe tether at ihe at least one target retraeiioo: rate (e.g., defe ed ^' based mi detected oscillations and/or established via manual engineering input). Additionally or alternatively, (lie control sysiem may operate the motor is fee second ntede to- deploy the tether at fee at least one tar et; deployment rate (e.g.,. determined based on detected oscillations and/or established vk manual engineering in ut). Widr this arrangement, the control system could thus -use various specific approaches lot damping oscillations via control of the tether at various rates.:

J03S3| For instance,, the control system may control the winding and/or unwinding of the tether, or the rate of winding and/or unwi ding of the tether to ''pltmp" the payioad muc like a swing, with tetter let out as the pay load moves toward the bottom of the swing nd tie tether held last (or even wound in) as the payioad moves towards the tops of ihe swing. Moreover, a "pum ing" feqnency, period, and/or phase of the tether may he respeetiveiy -matched. to -an oscillation i equeRcy, period, and/o phase of the payioad. By doing this, the energy of ihe swinging payioad may be removed even as the UAV remains, suhstantial!y stationary.

f0354| Furthermore, the extent of "ptiniping" of the winch .may depen on the distance between the payioad and the C¾V, whielr corresponds to tb ttawouMd length of the tether. Specifically when there is large distance between the payioad md the OA¥, the pendnlat uction of the payioad ma he very slow. O the order of ¼ hertz for instance. At this point, the amount of the tether unwound or wound onto di winch darin "pumping" of me winc ma fee on the order of meters. S«r when the payioad is closer to the l?AV, the pendniar ra&tioB may speed up to on the order of ! hertz or more for instance. In this case, the amount of the tether unwound or wound onto the winch during "pumping' ^* ma be on the order of centimeters..

|035$| Yet further, the rate of speed at whic the tether is wound or nnwound mm vary from one period of oscillation to the next as the distance of the payioad to the UAV changes, and ma ev¾n be varied within a single period of oscrBation. For example* the rate of winding _, or usiwindiu may he proportional to me velocit of the payioad or t e velocity of the payioad squared. Other examples are possible as well.

|0356 Wife tins arrangement, the control system, may ^* 'pnmp" fee winch while operating in the tether retraction mode to engage i ascent of the payioad or while operating in the tether deployment mode to engage in descen of the payioad Specifically, during descent of the psyjoad, he oscillations of the payioad m y fee damped by letting tether out at as the payioad approaches die bottom of the swing. Whereas, when fee payioad is moving towards the top of the swiag, fee amount of tether usswound from the meli coutd be reduced or slopped, or the tether cmM mm. be wound in as the pay load moves to the tops of the swing. Such ' ^{^} pum ing ^* ' of the tether may eoiinteraet the pendaiar motion of the payload t eontroi and damp the oscillations, of the payload. Is contrast,, during ascent of the payload, the oscillations of die pay toad may he damped by inding the tether m ^' as the payloa moves to the tops of the swing. Whereas, when the payload is moving towards the bottom of the swifig _s . the tetter could be uuwoynd, w stopped^ or wouu : In at a ted«eed rate:, Other approaches arc possible as well.

iv. IM M&v0m ( i Dampen QseMat ns

{ 57) : in accordanc ith an example implementation, the P 's eooiroi system .may dampen oscillations of the payfoad by directing the IJA.V itself to Move in various ways throug out .physical space. With this approach, the control system ma direct the UA to reaetively move in a manner that offsets, prevents, or reduces movement of the payktad diffing ascent and/or descent of the pay load. Although various such movements are described below, other movements are possible as well without: departing from the scope of the present disclosure.

|0358| .More speeifical y, the control system may he operable to deteriaiae- a target path of the pay-toad 'T is target path ma be a .target path of ascent of the payload during winding of the tether or may be a target path of descent of the payload during; a winding of the tether. For example, the target path may be swhstaatiaUy perpendicular to the ground and may ex send from, the ground to the: UAV. In this way, the ^■ control system may eft¾c»ve y plan to maintain the payload substantially beneath the UAV as the payload is being lowered or raised. But oscillations of the payload may cause the payload to ove away from the target path as the payload is: being lowered or raised,

(03 J To help $oh¾ this problem, as noted, the control system may cause the UAV to move In various ways. Specifically, at a give point hi time, the control system may use the detected oscillations of the payload as basis for determiniiig a position of the payload rel tive t the target path. Then, based On the determined position of the payload relative to the target pailt the eontroi system, ma determin a movement to be performed by - he U V so as to move the payload closer to the taiget path, and the . control system: may cause the UAV to perform that determined movement As such, the control system could repeatedly determine soch- movements as position of the payload relative to the target path changes over time due to oscillations,, and e nld repeatedly ea«se die UA V tp perform moveineuts to help dampen, fee oscillations.

S3 f0369 By way of exam le, the peftdular motion of the payload could be controlled, fey moving or translating the DAV hot i¾ontally in response to the motio of ihe pay!oad, e,g. by attempting to maintain the payioad beneath the UAV. -Oscillations of iie payioad. (e.g., pendidum-like s ingin ) would he damped by having ike UAV translate (e.g.. Move back and .forth) in such a way that the oscillations are mmimized. For s tance, the control system may determine .that a- querent position of the payioad is at a particular distance away irons t e tar get path and. that the payioad is currently moving, in a particular direction relative to the target path.. Responsively, the control system may immediately cause the IJAV to horizontally move in the particular direction and do so by an amount that is based oft the articular distance, thereby attempting to maint in the payioad beneath the UAV. hi this manner, the control system ma reactively determine horizontal movements thai offset horizontal forces on the payioad, and prevent or damp the oscillation of the payioad. Other examples are possible as well.

B. Selection of ^' Damping Techniques

[03&1 J Figure 33 is a flowchart illustrating ii method 3300 for selecting on or more damping routines teehnit es to help ampen oscillations of die payioad. I» praeftce, tie UAV's control system could: carry out method.3300 while ojSetatiftg in tether reunion. mode- or whil operating in tether deployment -modci I» accordance with block 3302 of method 3300, while the tether is at least partially unwound, the control system ma select one or more damping routines from a pluralit of available damping routines to dampen the oscillations of the payioad. And the control, system Way then perform those selected damping routines,, as shewn by block 3304,

3621 In accordance with the present disclosure, the control system may select any one of the above-described damping routines. Specifically, the control system, inay select any ^■ combination of the following routines: forward flight to dampen, oscillations* " o limp** technique to dampen oscillations, winding unwinding of tether to dampen oscillations, and/or UA V movement: to danrpen oscillations, hi practice, however, the control system could also select other damping routines: that are not described herein, and then, perform such dampin routines individual ly or in combination with, any of the above-described damping routines. |0363| Moreover, the control system, may select the damping routines based on various factors, some of which are described, below, Iti practice, die control system ma use any combination of those- ^' factors as basis for the selection, perhaps giving certain factors more weight compared to others. Although, ex mple factors are described below, other factors are possible as well without departing from tire scope of tire present isclosure

routines oased. on aa. operating mode of the motor. Specifically, dte control system ma deterursne whether the motor is operating in the first mode in which the motor applies torque to the tether Its a winding direction -or whether the motor is operating in the second mode in which the motor applies torque to the tether in an unwinding direction. Based at least in part on the determined mode of operation of the ^■ .motor _* tlje control syste may then select , one or more clamping roitife.es. For xam le^ if the motor is operating in. die second .mode, the ■control system may select: any damping technique otter than ie for ward flight damping technique, so as to avoid further increase of the unwound tether length in preparation for sad/or ^■ dtiring forward flight.

| 3(¾{ In yet another case, the control system ma select the one or more damping routines based on an operating mode of the UAV, Specifically, the control system m determine whether the UAV is operating i a payload pickup mode in which the UAV attempts to pick tip the payload or whether the UA is operating a payload deliver)' mode in. which the UAV attempts to deliver a payload. perhaps respectivel determining a state of payload delivery or of payload pickup. Based, at least in part on the deterMined mode of operation of the UAV , the eooirol system nay then se lect one or more damping routines _* For example, the cont ol system may select the i¾rward. flight damping technique if the UAV is engaging in post-delivery tether retraction as part of the payioad delivery mode, la practice,, the control system may do so hecause the UAV can begin forward flight to the nest may be carried out in olitcr -situa-fioas as well. For Instance, me control system may be configured to carry out one or mere dampin teehniipe during certain phases of flight a&d¾r ui Rg certain phases of payload pickup and or delivery, smoag other possibilities, to: this instance, Ihe control system, ma carry mi those damping eehmques w.itkoni necessarily detecting oscillations of a payload. In this, regard, as noted, ffie eoHtrol system may carr oat tire datRpiag routine for a -certain time period, such as b Initiating a thner upon start of a d m ing roiitee md then ending the damping routine (and/or carrying out- other operations, seefc. ¾s . esuming tether retraction) responsive to detecting expiratio of that rimer. I this maaner, the control system, ma essentially ahe p eventative serious ¾.r mimmbe any oscillations that might he present

Faitere Betectfen and Correction Methods

A. Failure to Md^ase Payloa

}0374| As described above with inspect to methods- 1800 and 2600, the UAV may

Operate hi a, delivery mode to deliver a payload to a. target location and sitbseqweutly Operate in a release-verification mode to- verif that the payload has. separated from the payload coupling apparatus. However, mere may be-sitaatioas-ia which the payload does not separate from the payload eoit ling apparatus upon, delivery. F½r instance, the payload coupling: apparatus may become snagged on the payload such that when, die UAV motor is operated io cause over-run of the tether, the pay load coupling apparatus, remains coupied to the payload rather than lowering asd detaching itom the payload. Accordingly, the control system may detect such situation d responsively take remedial action by causing the tether to detach from the UAV rather than causin the payload to detach from the payload coupling apparatus,

|0375f Figure 34 is a flow chart illustrating - .method- 3409 for detaching a tether from, a UAV. Method 340 m y be carried out by a UAV suck as those described elsewhere .herein. For example, method 3400 ma he carried: out by a control system of a UAV with a winch system. Further,, the winch system may include a tether disposed on a spool, a motor operable in a first mode arid a second mode that respectively ©ouster and assist Unwinding of tlte tether due to gravity (e.g. _s b drlving the spool, forward or in reverse), a payload coupling apparatus that mechanically couples the tether t a payload, and a payload latch switehable between a closed position that prevents the payload from, being lowered from the UAV and an open posi tion that allows the payload- to fee lowered fi-oni the IjAV.

376 As shown by block 3402, method 34(10 .involves the control s stgiB of the

UAV operating the motor to unwind the tether and lower the payload toward the ground (eg., by pcffbrmiiig mettod .1800). The control system may be coafig ied to detect when itie payload contacts the ground and re^onsiveiy initiate a tether ove ru process to atteshpi to release the payload from tire payload coupling apparatus, as show b block 3404, Tether over-ran occurs when the motor continues to unwin the tether after the- payload has stopped lowering. Dttriag letfeer over-rtrs, the pay load coupling apparai¾s coniinues to lower as the tether is .unwound, while the payload remains stationary. This can cause the payload coupling apparatus to detach from the ayload, for lasia ee^ w en the payload is resting on a protruding arm or other hook-hfce mec anism of the payload eoapling apparatus. As described above with respect to met od 1 Θ, the control system may detect when the payload contacts the; ground b wul ting a speed dfar a current of the meter and determining that the motor speed and½ .motor current is threshold low. As further described above with, respect to aieihod 1800, initiating the tether over-run process may involve operating the moior in the second mode to forward drive the spool . in a. direction that causes the tether to continue to unwind even after the payload has reached the round,

f 37?J Typically, carrying out the tether over-run process would: cause the payload coupling apparatu to detach from the payload However, in situators where tire payload does not: release torn tire payload eoa ling apparatus, the tsth&t over-run process niay he repeatable up to a predetermined number of times, as further shown by bl ck 3404,

j¾3?8I I» practice, oace tire payload has reached the ground and the control system has carried out a first tethe over-rea proces to attempt to separate the payload coupling apparatus from the payload, the control system ma determine whether the payload coupling apparatus has actuall separated from the payload, based on the current of the motor (e.g,, b perforatin Mod s 2602· and 2604 of method 2600). For example, after operating the motor to cause tether over-run, the control system, may operate the motor t begin retracting the tether, and if the payload is still attached to the payload coupling apparatus, the mm. weight of the payload raay eaase the motor to draw atore current:. Accordingly, tire control system may deierniine that ihe payload is still attached to the payload coupling appafains b detecting that the motor current. -is threshold high.-

|037f J Responsive to making such a determination, the control system may repeat the processes of lowerin the payload to the ground, operating the motor t cause over-run of the tether (ibis time, perhaps, by some predetmnined additional length) _: , and then pulling upwards on the tether to test for payload separation, shown in blocks 3402 and 3404. These processes ma be repeated a number of times until the control system, detemiines that the payioad has separated from the. payioad coupiirig apparatus of until a threshold r urfeer of repetitions has occurred, as sfiown fey block 3404.

}038f I The control system: may track how many times the. processes of causing overrun: of the tether and testing for payioad separation have been carried oui arid may determine that these processes have, been repeated a threshold number of times without successfully releasing the payioad from the payioad coupling apparatus, as shown by block 3406. Responsive to ffiskiitg this determination, the control system may decide to abandon ftrtlher attempts to separate the payioad from the payioad coupling apparatus and may instead decide to separate tie tether from the UAV by operating the mot to allow d tether to unwin during ascent of the UAV, as shownby block 34f

fi38I| in practice, the control system may operate the motor to allow the tether to unwind by controlling a maximum current supplied to die motor. By limiting the maximum current supplied to the motor, the control system limits the amount of force that the motor cars exert OR the- tether. More specifically, the control system may limit the maximom current to a small enough valpe that the motor's: maximu upward force exerted on the tether is smaller in magijittide than the downward force on the tether due to gravitsnoriai forces an- the payioad. As -a result, the UA tnay iy upward, an the tether will continue- to uu iid due to the do nward force on the tether exceeding the upward force from, the motor. In. other examples,, the control system may merely tarn off the motor, allowing it to spin freely, in order to obtain similar -results..

|0382| ^' Further. as n ted above, the tether ma be disposed on a spool. More spedfieaiiy, a first end of the tether may be ¾ion~fixed|y wound -on the spool. As such, when the te ler completely unwinds from the spool the tether may detach and fall away from the spool. Thus, whiie the control system operates the motor to- allow the tether to unwind, the control system may &rtlwr cause the UAV to initiate a. flight to a different location 1e.g„ a return location),-, sueh- that the flight of the UAV unwinds the tether and separates the tether from the spool, thereby releasing -the tether from the UAV, as shown by block 3 10, In this manner, when the payioad cOnphng apparatus is unable- to detach from the payioad,. both the payioad. and- the tether may be left behind at the delivery location, allowing the UAV to safel navigate- away.

B, Saag Detection

f QM3 A UAV carrying out tethered pickup and delivery of pay loads accordin to the processes disclosed herein may Snd itself operating in various different types of e yh uin Ms with various diflerent issues to address. One issue ma involve undesirable or unexpected forces exerted on the icther. For instance, a ptf&mi may excessively yank on die tether, or the tether ^' migkt get snagged on a moving o stationary object, resulting m a d© sft¾si force on -i e ^: tet!ief. -Other examples are possible as well, its these sUostioas, if the downward force is great enough, the OAV cotld be iilied oat of its fligiitj perhaps damaging the UAV, Ike payload,. or riearby. persons or property. Aeeordisigly. the control system may detect when certain forces are applied to the tether during delivery of a payload. and responsiveiy take remedial action by allowing She tether to t«m½d from its spool.

|038 J Figure 3 is a flow chart j!Jwsirating a method 3500 of detecting and addressing wiidestrabie downwar forces on a tetker when lowering a payload toward the gi¾«twL Method 3500 m be carried out by a IJAV suck as those described, elsewhere kerein. For exam le, metkod 35CKJ May be carried -out by a control system of a OAY witk a iBck system. Further, the which system may include a tetke disposed on a spool, a motor operable in a first mode and -a. second mode that respectively counter and assist rewinding of the tetker due to gravity (e,g. _i: by driving the spool forward or ip reverse) _* a a l ad couplin apparains tkat mechanically couples the tether to a payload. and a payload latch switehable between a cl sed positioji tha prevents ike payload fronv being lowered irons the OA V and an open position that ajlows tke payload to he l wered fro tke UAY.

|03§SJ As shown by block 3502, method 3501) involv s the control system, of the UAV operating ike .motor to cany otit tethered: deliver of a payload (e.g.., by pcrfenniog method I $00). Daring the process: of delivering the payload to a target location, tke control system may detect at* undesirable downw rd.; fb¾e on the terher As described above,, the presence of additional weight (or hi this case, the presence of a sufiioleftt do wnward force) OR ike tether may result in an increase in, enrreiit supplied to the motor in order to maintain a desired rotational speed of the motor. As suck, the control system ma detect an undesirable d wn a d force OR. the tether based on the motor current Further, in- order to av id false positives, the control system may also consider how long tke motor ciirrent is increased.

38 Additionally, ike control syste may consider an unwound lesgik of ike tetker when detectin sin undesirabl downward force. For instance, m order to limit the de-teetion of downward ferees to sou ces a t or near ground level {e.g., detecting -S person yanking on the tedier), ike control system may also determine kow far tke tether has keeB unweuBd from the spool iti order to dcteniiine whether an part of the tetker is at or near -ground level. Other examples are possible as well,

Θ387 Xhns, In practice, during the process of. delivering tke payload to a target location aad wkile the IJAV is in flight, the eoatfel system may determine an unwound length of the tetter based on encoder data representisg a rotation of the tether spool, and the control systera may de¾t»iae a motor &m t based m a s ii sensor of the Motor or the power system of t e IIA.V. Farther, the control system may determine that both (a) the u vound length of tether is greate than a threshold length and (b| the motor current of the motor is greater tftan a threshold ctifrent for at least a predetermined timeout period, as shown Mock 3504. Responsive to making such a determination, the control system may operate the motor to allow ^' the tether to unwind when the UAV ascends (e,g., as described above with respect to block 3408 of method :M00J, as shown by block 3506. And fwfo responsive to ma ug the determination, the control system may cans© the OA to initiate a flight to a dtfi¾r¾Bt location {e,g:„ a retiira location), such that .the : light of ^" the UAV unwinds the tether and separates tile tether f m t e spool, thereby releasing, the tether from the UAY, as shown by block 3508. this manner, when an undesirable downward force is exerted on the tether, the tether may unwind, and detach ftotn the UAV, allowing the UAV to safely navigate away, f 0388f In other examples, rather than detecting a snag and tes orisively operatin the motor to ind and release the tether, snags may he resolved by imposing a enrrent limit 0» the motor when picking up a payload, hhihtltsg the motor current t a «Μχίηηηη value limits the amount of force the motor can exert ik& tether, which i«ay prevent DA .fteta crashing if the tether becomes snagged,: For instance,, if the current limit Is low enough that the nmximura upward- force exerted o tie tether by the motor is weaker than a downward force on the tether, then the current linrii on t¾e motor relay allow the tether to completely •unwind, and detach om its spool , should the OAV fly awa while the tether is snagged, [0389 ¾ addition to experiencing undesirable forces during delivery of a payload, the tether may also experience undesirable forces during pickup of the payload,. For instance, when winching a payload from the ground toward the UAV, the payload and/or the tether m become snagged on various objects, such as trees, buildings, or various other nearby objects. As another example, an unexpectedly heav payload could be attached to the tether, resulting in an excessive downward force en the tether that prevents the UAV ^' from liftin the payload. Accordingly, the control system may detect when certain forces are applied to the iether during picku of a payload and responsiveiy take r medial, action.

|039QJ Fig re 36 is a flow chart illustrating a method 3600 of detecting and addressing undesirable downward forces on a. tether when winching a payload toward a IIAV. Method 361)0 may be carried oat b a UA.V such as those deseribed elsewhere herein,. For example, method 3600 m y be carried otn by a control system of a UA V ^' ith a winch system. Further, the winch system may include a tether disposed o a. spool, a niotor operable is a first mode sad a second aiode that respectively counter and assist aawisdssg: of the tether due to gmvity ^: (e.g., b driving the spool forward or in reverse), a pyload coupling apparatus that ffiecKanicaiiy eoitples the tetter to a payload, and a payload laten swtteriable betweerr a closed posi ion that prevents the payload from being lowered from tile UAV and m open position that allows the payload: to be towered from the UAV,

J039lf .As shown by block 3602, method 36 0 involves the control system of the UAV operating the motor to carry oat tethered delivery of the payload e.g,. fey performin method 170Θ). Poring a process of picking up fee payload to he delivered, and while the UAV is ever or near to a picloip location, the eoatrol system may determirie that a payload coupling apparatus is ttiechanicaiiy coisp!ed to a payload ^' fe.g. _f based on the motor earrent as described above with respect to method 1700). arid may responsivel operate the motor t retract the tether and lift the payload toward the UAV, as shown, by block 3604.

j0392) While retracting the tether,, die control system may detect- an error condition when the: tether and/or the payload becomes snagged, in order to detect a snag, the control system may pioaitor the motor cyrreni As described above, adding a downward force to the tether may cause an iaerease is motor current in order to eowtrtetact the downward force and riiairttairj a motor speed set by speed coattoHer. Thus, when the tether and/or the payload beco es snagged, the motor cttrrent tmy increase as the -motor attempts to rrolntain the rotational speed set b the speed controller. However., as also noted above with respect t rftethod 1.700, as increase: in taotor enrrent nia be indicative of the payload reaching the UAV after winching is complete . AceotAngfy, the control system, may also monitor and consider a unwound length of fee tether when defecting a: snag. For instance, if the unwound length of the tether indicate that the payload lias not yet reached the UAV, then the control system may detect a snag: On the other hand, if the unwound length of the tether Indicates that: the payload has reached the UA then the control s stem may not detect a snag, Thus, white retracting the tether with the payload coupled thereto, the control system tnay detect an error condition when both (a) an un wound l ength of the tether is greater than a threshold length and (b) a motor current f the motor is greater than, a threshold extent,, as shown by block 3606,

103931 ^β a ease, _: after detecting the error condition,, the control: system May make an attempt to correct the erro condition by operating the motor to unwind the tether (e , by a p¾determinsd length), and may then esume seteactittg the tether, as shown by block 3608.: Urjwinding tlie tether may add slack to the tether, perhaps allowing i eight of the payload to ando the detected .snag. In soase examples, the control systera may cause the UAV to repes tiea- itself before resumiag retracting .the tether in order to improve iiie cbaaees of Uiidoisg the snag aad/or reduce the chances of eneotBrtermg the -safcik snag.

}039 | If, after -jpesumiog _. . the retracting of die tether, the control system detects that the error condition is still, present Ce.g,, as shown by block 3i¾¾¾ i&e control system may repeat tile attempt to correct the error condition by repeating block 3608, and die eontroi system ma monitor the nuai er of repeated correction attempts. Once the control system deterniin.es that a predetermined number of attempts to correct the error condition have been made without s eeessfo!ly correctin the erro condition,, die control -system may responsively end the process of picking tip the pay load and initiate a pay load delivery process to return the payioad to the grmrod at or nea ike picku locstion, as shown by block 3610. More spedfieally, the control system -may operate the motor to lower the -payioad to the ground as if .it was performing a payioad. delivery according to metho 1800,

€. Failure to Pick Up Payioa

{0-395 J Occasionally* ¾hen a DAY ttempts to pk up payioad for tethered delivery (e.g., by perfornsiHg metfiod I7(M)) _:s the tJA.V may retr et the tether before a payioad h$ts been attached ^' to the tether. For instance, -while perforating meted I 7QCJ, the coatrot .system of the UAY may falsely deierrnine that a payioad is attached to the tether at blocks 1708 and 171 (e. _. g;,, clue to mw& -QX somefhiag pulling on the. tether during the predetermined attachment yeriilcatioa. period) aad responsively operate the motor to retract the tether. Accordingly, the control system may be ^• configured to deternn e, duriag retracting; of the tether, that a payioad is not actually attached to the tether

f 39SJ Figure 37 : a flow chart of a method 3700 of detecting that the UAV failed to pick n payioad. Method 3700 may be carried, out by a UAY such as those described, elsewhere herein. For example, method 3700 may be carried oat b a control system of a UAV with, a winch, system. Further, the winch system may include a tether disposed on M spool, a motor operable ia a first atode and a second mode that respectively counter and assist unwinding of die tether due to gravity (e,g,, by drivin the spool forward or ia reverse), payioad: coupling apparatus tha eehameaily couples the tether to a payioad. and a payioad iaieh. switehahie between a closed position that pre vents the payioad fior being lowered frost! the UAV and an opea position that allows the payioad to he l.ow-ered. from the UAV, |Θ3*>7| As shows b block 3702, method 3700 invokes- the control system of the UAY operating the motor to carry oat tethered deliver of the payioad (e.g., by perforniing- method 1700). During, a process ot pieking op the payioad to be delivered.,, and while the DAY is over or near to a picku location, the control s stem may operate the motor to tra ind the tether and lower a pay b ad Coupling ..apparatus t an expected: paylo-ad i\i tachmest altitude, as shewn by btoek 3704. As noted above, the payioad attachment altitude i»ay be m attitude at which a hamaR, or perhaps a robotic device, may grab the: payioad coupling apparatus for attaching the coupling apparatus to a payioad. For instance, the payioad attachment altitude may be an. altitude less Chan two meters above ground level,

|CB98f .Alter !oweriiig _: the tether, the control system may watt for a predeteraiise pay!oad aitachuient period, as shown fey hjoefc 3706. This atiaehmcRt period allows time for a hu aR, or perhaps a robote device, -to attach a payioad. to the payioad coupliRg apparatus. 039¾ ¾' hen the payioad attachment e i ends, the control system ma perform an attachment verification process _* as fRrther showo by block 3 &, I» particular, the attachment verification process may invol ve the control, system operating the motor so as to eounter unwinding of the tether lor a predetermined attaehtneM verification period, (e.g., by pulling upwards on the tether in order to hold d tetlier in place or retracting the tether at a certaiR rate), as shows by block 37t½a> The motor citrrent required to hold the tether in place or retract .the tedier at a certain rate will be greate when the payioa is attaehecL due to the added weight of th payioad As s«ch _$ the attachment verification process may further involve the control system determining, hasee at least in par on otor current during the predetermined attachment verification period, whether or pot the paytoad. coxipfing apparatus is niechanjc ity eoitpied; to the pa ioad, as shewn by Meek 3?06b, For instance, as discussed above, the control system may deteitmne the motor current based o duta ft¾m a eurreat sensor of the motor or of ^" the power syst m -©f ^' the l AV. if, during the aUaehment verification process, ^' the motor current exceeds a threshold, current value, then the contra! system may determine that the payioad is eoitpied to the paytoad coupling apparatus. Oil Che other hand, if the .motor current is below the threshold ewrreni value, then the control system, naay determine that the paytoad coupling apparatus is not eonpted to the payioad.

|8 §0J Further, when the contr system determines t at the payioad coupling apparatus is not mechanieaiiy coupled: to the payioad, the control system can cause the UAV to repeat the lowering of the payioad coupling apparatus and the attachment verification process in order t reattcirmt pickup of the payioad, and sn some embodiments these processes may onl be repeated tip. to a predetermined number of times, as shown by ock 3706, At this point rather than attempting to pick np the payioad again, the control system may eatsse the ..UAV to abandon the picku and aavigate away, in practice, for instance, the control system ma determine tha the attae!imeut verification process has been repeated a predetermined number of times without successful coupling of the payioad coupling; app&fatns to the payioad, and respousiveiy initiate a process- to cancel pickup of ^' the payioad and initiate tight o-f the UAV ^" to a next, -different location _* as shown by ^' block 3708. lie dti&rent location may be another pickup location, or it may bo some ot er location, such as a UAV dock for docking and/or storing the ^" UAV. Other examples are possible as well

}0461| As noted above, there may fee simation when control system falsely, determines that a payioad is attached during the payioad verification period, and the control system may responsively cause the motor to enter a winching state to retract the tether toward th HAY. Accordingly, in order to reduce such false deter ninarioris, the duration of the predet rmined attachment verifieatioa period described above ma be increased. Additionally or alternatively, the control s stem- ma be farther configured to esf HS the attachment verification process and tether lo ering process as .shown by bioek 3706 while operating in the winching state.

D. ayioad Laid* Failure

4(Sf As described above with respect to tiietbod \W(% when a UAV sueeess&ily picks tfp. payioad and pulls the payioad or payioad coopbng apparatu into receptacle of tile UAV, the control sy stem may close a payioad latch to secure the payioad to the UAV.. However, there rnay be sanat ons- where the c&atroi sy stem fails to close the latch (e.g., 4»e to m obstrtfction or iot other issue) or where the control system closes the latch but the closed latch f its to secure the payioad to the UAV. Accordingly, the controi system rnay be configured to determine wbether the payioad iateb has sueeesst lly secured the payioad to the UAV.

|04β3| In some embodiments, the control system ma operate the motor to pub upwards on the tether prior to attempting to close the payioad iateb. If the pa ioad and/or payioad couplin apparatus have reached the UAV receptacle, me payioad coupling apparatus is pressed up against the U.AV such that the motor caimot retract the tether any fiirther. At this point, closing the payioad latch may successfull secure the payioad arid/or the payioad coupling apparatus t the UAV, On the other hand, if the payioad and/or payioad couplin apparatus have not yet ireached the UA V receptacle, then the motor may still be retracting the tether, an closing the payioad latch, at this point would tmsiiceessbi!ly secure the payioad. Accordingly, when closing th payioad latch and/or for a time duration after closing the payioad latch, the control system may be - configured to monitor the motor speed to determine whether the payioa latch successfully closed and secured the payioad to the UAV, for. instance, responsive to detecting that the motor speed is above a threshold speed. the .control system may deierrttise feat the payload latch Med to. successfully close and/or secure the payload to the UAV.

j0484f lh other en#ot£mient¾ after attempting to close the payload latch _* the control system may detect pay load latch failure by operating the motor to unwind the tethe a predetermined length, If the payload latch was successfully closed, to engage th payload or payload: coupling apparatus, then the payload: or payload coupling apparatus may be arranged within i e UAV receptacle such that all or a portion of die weight of the paytoaii rests on the ■payload. latch rather than the tether, and the motor current might be below a threshold current (e.g., approximately zero). On the other hand, if the payload !ateh failed to close, then the weight of the payload might be stajported by the tether, mii. the motor current tegsired t .support: the weight of the payload might be above a ii»eshold etrrrersL Accordingly, the control system may de errniHe whether the payload latch siuecessf ily closed based the motor euftent of the ^' UAV.

|O405} In aay ease., responsive t ^■ detecting that the payload fetch failed to close, the control system may operate the motor to winch the payload back toward the UAV and teattew t ciosfcg: the latch _* This process may he repeated up to a predetermined sutafeer of times. or until the payload latch is successfully closed. After unsuccessfully repeating the process the pte e nnned ranafeer of times, the control system m y responsively operate die motor to lower the payload back to the. ground and detach the pay load from, the tether (e.g., by: _: pcriojtrung niethod: 1 B i.

Q466 The following fa hie provides a brief representati n of the various methods for detecting and resotviag errors as described above:

system determines whether the payioad is attacked to the payioad couplin . apparatus based osi a motor current supplied to the motor when the Motor attempts to hold die payioad coupling apparatu at a constant altitude or begins to retract the tether toward the UAV. If the motor current is below a threshold current during the VERIFY PAYLOAD stat 3808, the control system returus. to. the LOWERING HOO state 3804 to rea.tiempt att ch ent of the payioad. As described above with respect to method 3700, this repetition may be repeated number of times u t l a limit is reached. Once the limit is reached,, tire control system may cause the l!AV to retract the tether, ascend, and perhaps return to the IDLE state 3802 from which the UAV may navigate to some other location.

|0 1¾ On the other hand, if, daring the VERIFY PAYLOAD state 3:808, the control system, determines that the payioad has been attached to the payioad coupling apparatus (e .g.,. by detennistng after a time delay that the motor ew-rent is at least a thresbol current), the control system may eeter a WiMCHiNG EAYLOAP state 38 0. Daring thi state:, the control system may operate the motor to retract: the tether and pull the payioad toward the UA V. As described above ' ith respec t to meth d 3700, the con trol system may also monitor niotor cttrretM in Urn- state to determine whether a false positive was obtained daring the VERIFY PAYLOAD: state 3808 by detecting that the motor current Is threshold low),. Addilsoually, noted above with respect io method 3S0Ci the control system may monitor the motor current during the WINCHING- FAYLOAD slate 3810 in order to detect when the tether becomes snagged, (e.g., by detecting; .that .ihe motor -current is threshold high). Responsive io detec ng, snag _s the control system may operate the motor lower the payload a predetermined length and tcatscmpt winching the payload. After a threshold number of atje pts to remove the snag, the coMrol system may operate the motor to lower the payload to the groii»d and abandon pickup of. the payload. This may involve advancing to a DESCENOrNG state 3822, which is discussed in more detail beiow.

f lli While operating in the WINCHING- PAYLOAD state 38 0, if no snags are detect d _: , or if all detected snags arc resolved, the con ol system may detect that the payload is w thin, a. threshold distance of the .UAV (e.g^. by measuring a nisniber of oialions of the tether spool) and responsively enter an ENGAGING PAYLOAD state 3812, During thi state, the control system m y increase- the current .supplied to the motor tor a predetermined time period s order to attempt to pull the payload- into, and orient the payload wiifei , a receptacle of the .UAV. ¾ during this state _* the control system detects that the motor current is below a threshold current and or that the tether is unwowad at least a threshold, length, then the eoatrol syste may responsiveiy determine that the payload is too far from the UAV and ay ^' .re-enter the WlMCHlKG FAYLO D state 3810 until the control system again detects that the payioad is close enough to the UAV to advance to the ENGAGING PAYLOAD state 3812.

{04121- On the other hand, if, during the ENGAGING PAYLOAD state 3812, the motor current remains threshold high and the unwound length of the tether indicates that the payload has reached the UAV, then the Control system enters the LATCHING PAYLOAD state 381.4, During thi state^ Ihe eoatro t system switches the payload latch to the closed position, thereb preventing the tether and/or the payioad frorn descending from the UAV. As described above, the control system may determine whether th paytead la!eh. was successfully closed fey monitoring the motor speed and/or by operating the motor to attempt to lower the payioad aad moniiortag the moi current. If the control system determines that the payload latch was not successfully closed, the control -System ma return to the iNCfflMG FA YLOAD state 3810 and reatiernpt to lift and engage the payload: Bnt if the control system deteraiines that the payload latch was saceessmlly closed, then the control system may enter- a WAITING TO DELIVER state 381

{0415j The WAITING TO DELIVER state 3816 may be s milar to *tse IDEE state

3802 where the payload is secured to the U Y, and the control system perates the motor to kee the ayload stationar . If, after a time tielay, the control: system detects that the moto speed is .greater titan a threshold speed, this .ma indicate thai the payload Is not sui cieatly secured to t e- WAV, and the control system; may responsrvely return to the WlNC iMG PAYLOAD ^' state 3814 Otherwise, enfsrin fhe WAITING TO DILI E tate 3 16 signals the end of the pickup mod e,

| 414{ While in the WAITING ΓΟ IIEOVER. state 3816,. the control system mm receive a command to deliver the payload and; may responsively enter a deliver mode (e.g., by performing Method 1 Miff}, The delivery mode may iBchide a PRl-DRGP TENSION state 3818, In this state, while the payload latch is -closed, the control system ma operate the motor to l ft the payload (e.g., by setting the desired tether speed to 1 m s or some other speed i -an to a d direction, or by setting the motor etnreot to a predetermined v lue), thereby removing: the weight of the payload from the payload latch and makin it easier to open the payload latch. While in the PRE- DROP ENSION stat 3ilS, the control system: may open the payload latc and advance to the POST-DROP TENSION ^' state 382 ⁽ after -a time delay, hi this state; the control syste may operate the rnoter to hold the tether in a eonsiantpositiori for a pf edeternhried. amount Of time to allow me weight of the payload to pull the pa load firmly agaiast the payload cou ling apparatos, thereby mdneing any chance mat the payload might, slip off and detach from the payload coupling apparatus. After the predetermined .amount of time has passed, the control system ma enter the DESCENDING state 3822, }0415f la. both the PRE-DROP TENSION ^' state 3:818 and the POST-DROP

TENSION ^' state 382(1, if the control system detects that the payload has traveled at least M threshold distance (e,g., ^' by measuring rotation of the spool), then this tnay indicate that an error ha occurred (eg,, premature detachment of the payload from the payload coupling apparatu or snapping of the tether) because the ^■ spool - should remain substantially : otionless during these states, .As result to detecting such an error, the control system may return to the IDLE; state 3802 and canse the UAV to navigate to a location where it may he serviced. }04i 6| In the BESC'ENDING state 3822, the control system may operate the ^' motor to unwind the tether according to a predetermined, descent profile that specifies a constant or varyin operational speed f the m to Opon detecting thai the tether has un ou d at least a predetermined a ount (e,g„ detecting that the payload is within a threshold distance of the gimaid ased ^' on a» altitude of &e U V), the coatrol syste m y ester a WAITING FOR TOUCHDOWN state 3824. & some exaaiples, the control system may also be configured- to advance from the DESCENDING state 3822 to the WAITING FOR TOUCHDOWN state 3824 if a threshold amount of imm elapses in the DESCENDING stat 3822 without advancing to the WAITING FOR TOUCHDOWN state 3824.

{0 *71 & the WAITING FOR TOUCHDOWN state 3824, the control system may monitor the mo tor current sod its operational speed in order to detect whether the pay load has reached the ground. Specifically, upon detennirtirig that both die motor e«rrent and die motor speed are threshold low, l¾e control system ay ester a POSSIBLE TOUCHDOWN state 38 6 to. verify that the payload has m fact: reached the grotiod. The control system may fee eontlg«red to .remain hi (he POSSIBLE TOUCHDOWN state 3826 for a predetermined amount of time. It during that time, either the Motor earrersi or the motor speed becomes threshold high, this may indicate that e payload has not yet reached the ground, and the control system may rrnnm to the WAITING FOR TOUCHDOWN state 3824. However, if, diffing the duration of the POSSiBLE TOUCHDOWN state 3826, the motor current sad the motor speed remain thiesho!d tow, this may Indicate that the. payload has in fact reached the groisnd, and the control system ma respoBSivel sdvaaee to a TOUCHED -DOWN ^' state 3828. hi some- ex mples, the control, system may also be cooSgarecl to advance from the WAITING FO TOUCHDOWN state 382 to the TOUCHED DOWN slate 3828 if a. threshold amount of time elapses in the WAITING FOR TOUCHDOW i state 3824 without advancing to. the ROSSiBLF TOUCHDOWN state 3826\

{Q4W$ Qn.c m the TOUCHED DOW state 3828,. the control syste may operate the motor to cause over-am ef the tether siteh that the payload coupling apparatus co hiues to lower while the payload remains stationary en the ground. Continuing to lower the payloa coupling apparatus may cause the payload coupling apparatus to detach from, the payload. After eassmg tether over-rait for a predetermined aMOnat of time, the control system ma enter a VERIFY RELEASE state 3830 ia. order to determine whether the payload coupling apparams did. -in fact separate from the payload.

[Q4t f In the VERIFY RELEASE state $ the control system may operate the motor to pull upwards OS the tether. Based the motor current when, pultiag upwards on the; tet er:, me control system may determine whether or not the payload has been released from the payload eonpilttg apparatus, if the motor current is threshold high, this may indicate that the payload is still attached, and the -control system ma return to the TQIiClIED D

1.02 state 3828. This process may be repeated «p to a predetermined du ber of times, at which point the -control system may enter a FREE SFt state 3832,

|042©| hi the FREE SPIN state 3832, the control system may operate the motor to allow the tether to coBipieteiy (stiwind such that the tether disconnects and fails awa from the IJAV. This .may be achieved by imxting the motor current to a sufficiently low -value- that the inaior is unable to counteract the downward force on the tether csttse by the gravitational pxt\l on the .payiaai Alternatively, the motor c be sjtet off completely (e,g;, limiting the motor current to 0 A).

0 211 Referring back io the VERIFY RELEASE state M, i£ tlirOBghottt a predete:rmined duration, the motor cira-ent remains threshold low, this may indicate - that tie payioad has is fact separated irons the payioad. coupling apparatus, and. the control system may fesponsively advancelo an ASCENDiNQ state 3834,

| 422} In the ASCENDING state 3834, the control system ma operate the motor to retract the tether a¾d the payioad coupling - apparatus up toward the ¹ UAV according t a. predetermined ascent profile that specifies constant or varyin operational speed of me motor, Once the control system deterotiaes thai an. unwound- length of the tether is belo ifetexhold length SBCO. that the payioad coupling, apparatus- is sufiieiently close to the D Y (e.g , based on a measured murs-her of rotations o f the spool), the control system may enter an ASCENDING PAUSE state 3836.

|04231 in the ASCENDING PAUSE state 3 ¾ iSie control system ma operate the motor to haii the refraction Of the tether. Once retraction of the tether is- halted, the control system may control a .movement of the IJAV in order to dampen any oscillations of the ieiher that may have occurred during the ASCENDING state 3834. After dampng the tether oscillations, the control system may -enter a FINAL ASCENT state MM,

|0424} n the FINAL ASCENT state 38 the control system may operate the motor to resume retracting me tether. However, in this state, the tether may be retracted at a slower rate than that of tie SCENDING state 3834. This slower rate may introduce weaker oscillations o the tether. Also daring the FINAL ASCEN state 3836, the control system may .monitor the motor current to determine when the payioad coupling apparatus reaches the UAV. In practice, hen, the payioad. coupling apparatus reaches the UAV, the apparatus is pressed against ^' the UAV, the motor speed drops to zero, and thenioior current increases ^' in ^' an attemp to Increase moto speed. Accordingly, the control system, may determine that the payioad coupling apparams has reached the IJAV based on the motor current exceeding a threshold entreat. Respoiistvely, the control system ma eater an ENCAGING state 3841},.

1.03 fu ¾5j !n the ENGAGING state 38 0, the control system ay increase ic M ximMrn motor current ½ order to: allow the motor to pail the payioad coupling apparatus ted, and orient itself ithin _* a receptacle of {lie UAV ^" . Once tie payioa couplin apparatus Is secured within the receptacle, the control system, may- .return ie the IDLE state 3802. if, during the ENGAGING state 384ft, the motor c«rrent fails below a threshold current, this may indicate that th payioad coupling apparatus was not i» fact near to the UAV, and the detected increase is current was likely caused by something else (e.g, _s ¾ temporary sna of the tetlter). In ch s. scenario, the control system may revert back to the FINAI, ASCENT state 3 R„

[0426] ^' As shown by the state diagram 3800, once he so ¾rpS system enters the SCENDING state the eoiiirol system, may repeatedly advance to the next state upon determining that a threshold amount of time has elapsed without advancing states,

| 27 In .some examples, a Sower maximum current limit may be imposed oft the

^' UAV motor when retracting; the tether, as shown by states 3834 to 3840, when compared- to lowering tlie tether, as shown by states 3818: t 3828, This is because the tether is more likely to encounter a snag whe retracting the tether. Imposing a lower current limit reduces the aniosmt of force that the motor may exert on the tether. This may prevent the motor fr ta causin the UAV t crash by continuing to winch: the UAV toward a snag. And as: noted above, if the c irrent limit is low enough that the axhnn . Iferce of the motor is weaker than a■ do n ard force on the tether, then the current limit on the motor may allow the tether to completely unwind and detach from its spool should the (JAV fly away while the tether is snagged _* Similar Methods may be -employe when initially picking tip a payioad d r ng states 38 to 3814.

XIV. Additional Aspects

|0 28| In some embodimeats, the control .system of the UAV may he configured to calibrate the rotar encoder and. speed controller of the motor upon startup of the system. In practice, when the U V system is initially powered on, the motor should he stationary. Accordingly, lite encoder data should also indicate that the. -motor is stationary- If the encoder dais ind cates otherwise, then an offset may be applied to the encoder data to account: for any inconsistencies.

|Q42 f The control system may further test the friction of the moto on startup of ihe

UAV system. Based on- tire measured motor friction, an offset; may be applied t various motor current settings to account for the measured motor hictioii. Over time, the friction of a DC motor may vary. Therefore, measuring friction on every startup and adjusting moto current: settings accordingly may enable consistent operation over the life of the motor. XV·.. Conclusion

}Θ43 | 'Die parrictdat arraa CEtteats shows in the Figures .should taoi be viewed as limiting.: It should fee tin eistoctii that "other iiMpieffiesiistisss hiay include more or less of each element sfaowa i a given. Figure, Farther, some of the Ohisiraied elements y be combined or omitted. Yet .taker, exemplar implemeittatioii may include elements that ate sot illustrated in the Figures,

043lf Additionally, while yariff&s aspects and ifa jementations have heea disclosed herein, other aspects mud implementations will he apparent to these skilled in the art. The various aspects and implep¾ntaoo»s disclosed herein are ih purpose of illustration and are not intended to be limitum, with the tee scope and spirit being indicated by the followihg claims. Other implementations may be utilized,, arid other changes may fee m de, witfeow departing frora the spirit or scope of the subject matter presented^ herein. It will be readily understood, that the aspects of the present disclosure, as gefteraSly described herein, and illustrated itt the figures, can be ar&oged* substituted, combined, separated, and. designed m a. wide variety of different configurations, all of whi ch ar contemplated herein.