TECHNICAL FIELD

[1] The present invention relates to a drone landing system, assembly and method. In particular, embodiments of the present invention relate to a drone landing system to allow a drone to land accurately.

BACKGROUND

[2] Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

[3] Autonomous and semi-autonomous air vehicles, commonly referred to as drones, carry people and cargo.

[4] Attempts to operate drones in metropolitan areas for the transport of people and cargo have been made but such a task is difficult.

[5] In particular, the operation of drones in metropolitan areas presents numerous problems, including manoeuvring, landing and aligning the drone with the people and/or cargo to be transported. Drones that are unable to land precisely may pose a safety hazard to those in the immediate area due to the propellers of the drone which spin at high rates.

[6] It is an aim of this invention to provide a drone landing system and method which overcomes or ameliorates one or more of the disadvantages or problems described above, or which at least provides a useful commercial alternative. [7] Other preferred objects of the present invention will become apparent from the following description.

SUMMARY OF INVENTION

[8] In an aspect, the invention provides a drone landing assembly comprising: a coupling assembly comprising a first coupling and a second coupling complementary to the first coupling; a landing station having the first coupling of the coupling assembly; a drone having the second coupling of the coupling assembly, the drone being adapted to be guided to: within a first predetermined vertical height and horizontal distance of the landing station via GPS; and align the first coupling with the second coupling within a predetermined tolerance level via an image processing assembly.

[9] In another aspect, the invention provides a drone landing system comprising: a coupling assembly comprising a first coupling and a second coupling complementary to the first coupling; a landing station having the first coupling of the coupling assembly; a drone having the second coupling of the coupling assembly; a first positioning system for guiding the drone to within a first predetermined vertical height and horizontal distance of the landing station, the first positioning system comprising a GPS; and a second positioning system for aligning the first coupling with the second coupling to within a predetermined tolerance level, the second positioning system comprising an image processing assembly, wherein the first positioning system firstly guides the drone to within the first predetermined vertical height and horizontal distance of the landing station, the second positioning system secondly aligns the first coupling with the second coupling to within the predetermined tolerance level, and when the drone is within the predetermined tolerance level, the drone is guided to the landing station by the first coupling and the second coupling, wherein the first coupling reciprocally engages the second coupling.

[10] In a third aspect, the invention provides a method for drone landing, the method comprising the steps of: guiding, via a first positioning system comprising a GPS, a drone to within a first predetermined vertical height and horizontal distance of a landing station; aligning, via a second positioning system comprising an image processing assembly, a second coupling of a coupling assembly on the drone with a first coupling of the coupling assembly on the landing station within a predetermined tolerance level, and when the drone is within the predetermined tolerance level, guiding the drone to the landing station wherein the second coupling reciprocally engages the first coupling.

[11] In a fourth aspect, the invention provides a drone landing assembly comprising: a drone landing station comprising a first coupling of a coupling assembly, the first coupling being adapted to engage a complementary second coupling of the coupling assembly. [12] Preferably, the first predetermined vertical height and horizontal distance define a cylinder. Preferably, the first predetermined vertical height and horizontal distance comprise a height of ±2 metres and a distance of ±1 metre.

[13] Preferably, the predetermined tolerance level is based on a maximum diameter of the first coupling or the second coupling.

[14] Preferably, the first coupling comprises a coupling device having a geometric shape. Preferably, the coupling device has a base and a head, wherein a diameter of the base is greater than a diameter of the head.

[15] Preferably, the second coupling is shaped complementarily to the first coupling to receive the first coupling therein. Preferably, the second coupling comprises a complementary receptacle for receiving the first coupling therein.

[16] Alternatively, the second coupling comprises a coupling device having a geometric shape and the first coupling comprises a complementary receptacle for receiving the second coupling therein.

[17] Preferably, the first coupling is conical and the second coupling is a reciprocally shaped conical receptacle. Preferably, the first coupling is a dome, hemispherical, a square-based pyramid, a pyramidal frustum or a conical frustum. Preferably, the second coupling is a reciprocally shaped receptacle configured to receive the first coupling.

[18] Preferably, the first coupling comprises a coupling pin and the second coupling comprises a complementary coupling receptacle for receiving the coupling pin therein. Alternatively, the second coupling comprises a coupling pin and the first coupling comprises a complementary coupling receptacle for receiving the coupling pin therein [19] Preferably, the system comprises a landing target. Preferably, the landing station comprises a base and the landing target. Preferably, the landing target is located on a surface of an object connected to or attached to the base of the landing station. Alternatively, the landing target is located on the base on the landing target. Preferably, the image processing assembly is adapted to identify the landing target and adjust a relative position of the drone to align the first coupling and the second coupling to within the predetermined tolerance level. Preferably, the image processing assembly is adapted to calculate a pose position of the drone based on the identification of the landing target. Preferably, a velocity command comprising a velocity is calculated from the pose position of the drone. Preferably, the velocity command is provided to the drone to adjust the position of the drone based on the velocity of the velocity command.

[20] Preferably, the landing target comprises a guide image or guide pattern. Preferably, the image processing assembly comprises a camera attached to the drone. Preferably, the image processing assembly is adapted to identify the landing target via the camera and adjust a position of the drone relative to the landing target to thereby align the first coupling with the second coupling.

[21] Preferably, the first positioning system comprises differential GPS (DGPS), wherein the landing station has a reference position (i.e. the position of the landing station is fixed at a known position). Preferably, the landing station comprises a GPS receiver for receiving a GPS-determined position of the landing station. Preferably, the landing station is adapted to calculate a difference between the reference position of the landing station and the GPS-determined position of the landing station to calculate a correction factor. Preferably, the landing station is configured to communicate the correction factor to the drone. Preferably, the drone and the landing station are configured with a wireless communication interface allowing wireless transmission and receipt of the correction factor therebetween.

[22] Preferably, the drone comprises a GPS receiver for receiving a GPS- determined position of the docked drone (i.e. when the drone is docked at the landing station). Preferably, the landing station or the drone has a reference position (i.e. the position of the landing station/drone is fixed at a known position). Preferably, the drone is adapted to calculate a difference between the reference position of the docked drone (i.e. when docked at the landing station) and the GPS-determined position of the docked drone to calculate a correction factor.

[23] Preferably, the coupling assembly comprises a locking assembly for securing the first coupling to the second coupling. Preferably, the first coupling is adapted to securely engage the second coupling such that the first coupling is secured to the second coupling. Preferably, the locking assembly comprises a locking pin and a cavity for receiving the locking pin therein. Preferably, the first coupling includes the locking pin and the second coupling includes the cavity.

[24] Preferably, the coupling assembly comprises an inductive charging system. More preferably, the coupling assembly comprises a resonant inductive charging system. Preferably, the first coupling and the second coupling have electrical coils therein for wireless charging when the drone is docked at the landing station.

[25] Preferably, aligning the first coupling with the second coupling within a predetermined tolerance level via an image processing assembly further includes maintaining the alignment of the first coupling with the second coupling within the predetermined tolerance level until the first coupling engages the second coupling.

[26] Preferably, maintaining the alignment includes measuring yaw of the drone, comparing the yaw of the drone within a yaw angle tolerance limit. Preferably, if the yaw of the drone is outside the yaw angle tolerance limit, adjusting the drone so the yaw of the drone is within the yaw angle tolerance limit. Additionally, or alternatively, calculating a position of the first coupling of the drone relative to the second coupling and comparing the position of the first coupling to the predetermined tolerance level. Preferably, if the position of the first coupling of the drone is outside the predetermined tolerance limit, adjusting the position of the first coupling of the drone so the position of the first coupling of the drone is within the predetermined tolerance level. Preferably, the position of the first coupling comprises a radius and angle of the first coupling relative to the second coupling. Additionally, or alternatively, calculating a velocity of the drone, estimating a future position of the drone from the velocity and comparing the future position of the drone to a second predetermined tolerance level. Preferably, if the future position of the drone is within the second predetermined tolerance level, initiating a landing of the drone to engage the first coupling with the second coupling. Preferably, calculating the future position of the drone includes calculating a future position of the first coupling of the drone. Preferably, the second predetermined tolerance level may be equal or different to the predetermined tolerance level.

BRIEF DESCRIPTION OF THE DRAWINGS

[27] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows: Figure 1 illustrates a landing station for a drone landing system;

Figure 2 illustrates a drone landing on the landing station;

Figure 3 illustrates a block diagram of the drone and landing station;

Figure 4 illustrates the landing station and a cylindrical alignment region the drone is to be guided to;

Figure 5 illustrates the drone within the cylindrical alignment region as it aligns with the landing station;

Figure 6 illustrates a locking assembly for locking the first coupling and second coupling together;

Figure 7 illustrates a resonant inductive charging system in the coupling assembly;

Figure 8 illustrates the position vector and velocity vector of a drone relative to the coupling of the landing target; and

Figure 9 illustrates a pseudocode implementation of a landing algorithm for a drone.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[28] Embodiments of the present invention provide a drone landing system, assembly and method for accurately landing a drone on a landing station.

[29] Embodiments of the invention utilise a three-step positioning system including GPS (Global Positing System), an image processing assembly (using image processing or Artificial Intelligence) and a mechanical coupling system to ensure the drone safely and accurately returns to its landing station.

[30] Figures 1 to 5 illustrate a drone landing system 10. The drone landing system 10 includes a landing station 100 having a landing base 102 mounted on a pole 103 and a first coupling comprising four coupling devices in the form of conical pins 104. The landing base 102 also includes a landing target 106, which will be described in more detail below.

[31] The illustration shows four conical pins. However, it will be appreciated that any number of pins can be used from one upwards.

[32] As can be seen in the block diagram of Figure 3, the landing station 100 also includes a computer 108, having a processor 108a and memory 108b storing Al/image processing/control algorithms, a wireless transmitter 110 and a GPS receiver 112.

[33] The drone landing system 10 also includes a drone 140 having a second coupling comprising four coupling devices thereon in the form of conical receptacles 142. The conical receptacles 142 are shaped to receive the conical pins 104 of the landing station 100 therein and are thus complementary to the conical pins 104 so that when the drone 140 is docked at the landing station 100, the conical pins 104 are received within the conical receptacles 142, as shown in Figure 2.

[34] The number of conical receptacles 142 matches the number of conical pins 104 on the landing station 100. It will be readily understood that the conical receptacles could be located on the landing station 100 and the conical pins located on the drone 140 such that the conical receptacles on the landing station 100 receive the conical pins of the drone 140. [35] As shown in Figure 3, the drone 140 includes a computer 144, having a processor 144a for image processing and memory 144b, a wireless receiver 146, a GPS receiver 148 and a camera 150.

[36] While both the drone 140 and landing station 100 are both described as having a GPS receiver, it should be understood that the GPS receiver may be omitted from either the drone 140 or the landing station 100 in some embodiments as only a single GPS receiver may be required.

[37] In use, the drone 140 would leave the landing station 100 to attend to a task (e.g. surveillance or a delivery, for example). Once the task is complete, the drone 140 must return to the landing station 100. However, this can be difficult and requires highly accurate positioning and guidance.

[38] As noted above, the embodiments described herein use a three-step positioning and landing system to allow the drone to safely, securely and accurately return to the landing station, through a first step (coarse positioning), a second step (medium/finer positioning) and a third, mechanical coupling step.

[39] The first step brings the drone 140 to within a predetermined vertical height and horizontal distance of the landing station 100. This is represented by a cylindrical region 160 shown in Figure 4 having predetermined horizontal distance r and vertical height h. Effectively, the drone 140 must be within a volume defined by the vertical height and horizontal distance.

[40] In the first step, the system utilises GPS technology to position the drone 140 with a horizontal accuracy of ±4 metres (i.e. 8 metres of accuracy). It is known that vertical accuracy of GNSS/GPS receivers is approximately 1.7 times the horizontal accuracy. Thus, it is expected that the vertical accuracy is approximately ±7 metres (i.e. 14 metres of accuracy). [41] The Inventor envisions that in some embodiments, the accuracy of standard GPS may not be sufficient.

[42] In some embodiments, the system 10 also includes differential GPS (DGPS) to improve the accuracy of the drone 140.

[43] In one embodiment, the landing station 100 has a reference position (i.e. the position of the landing station is fixed at a known position that does not change). The GPS receiver 112 of the landing station 100 receives a GPS-determined position of the landing station 100 and calculates a difference between the reference position of the landing station 100 and the GPS-determined position of the landing station 100 to calculate a correction factor. Advantageously, the landing station 100 acts as its own DGPS reference site.

[44] The landing station 100 then communicates the correction factor to the drone 140 via the wireless transmitter 110.

[45] In an alternative embodiment, the landing station or the drone has a reference position (i.e. the position of the landing station/drone is fixed at a known position and does not change).

[46] Before launching from the landing station 100, the drone 140 receives a GPS- determined position of the drone 140 via the GPS receiver 148. The drone 140 then calculates a difference between the reference position and the GPS-determined position of the docked drone 140 to calculate a correction factor. Advantageously, this allows the drone 140 to act as its own error calibrating reference before it leaves the landing station 100.

[47] In some further embodiments, if there are a plurality of drones and associated landing stations, this may act as a network of reference positions for DGPS correction. [48] The Inventor envisions that through DGPS, positional accuracy of ±1 metres horizontally (r= 1 ) and ±2 metres vertically (h = 4) is achievable. Assuming a safety margin of 2 metres above the landing station (represented by m in Figure 4), upon completion of the first positioning step, the drone 140 will be positioned within the cylinder 160 approximately 4±2 metres above the landing station 100 and ±1 metre from a centre of the landing station 100.

[49] In the second step, the image processing assembly positions the drone 140 from within the cylinder 160 to a position much closer to the conical pins 104. The horizontal accuracy is determined by the maximum diameter of the base of the conical receptacles 142. The apex 104a of the conical pin 104 must be within the opening of the conical receptacle 142 so that the apex 104a impacts the angled internal wall of the conical receptacle 142 which then guides the apex 104a towards the apex 142a of the conical receptacle 142.

[50] In operation, when positioned within the space defined by cylinder 160, the drone 140 utilises the camera 150 to view the landing station 100 below. Importantly, the drone 140 identifies the landing target 106 through optical recognition/image processing and determines how the drone 140 must be positioned and/or orientated to ensure coupling between the conical receptacles 142 and conical pins 104.

[51] While the landing target 106 is described as being below the drone 140, it will be appreciated that the landing target 106 could be located remotely or separately from the landing station 100 such that the landing target 106 and the landing station 100 are distinct objects. In some embodiments, the landing target is located on a surface of an object connected to or attached to the base of the landing station. Alternatively, the landing target is located on the base on the landing target. For example, in some embodiments, the landing target may be located on a surface of an object that is attached to the landing station, where the surface of the object is orientated perpendicular to the base of the landing station (i.e. the surface of the object is vertical and the base of the landing station is horizontal).

[52] Utilising image processing and artificial intelligence techniques, the drone 140 is trained to identify its position (x,y,z coordinates) and rotation relative to the landing target 106.

[53] Using this relative position information, the drone 140 calculates the movements required to align itself with the landing target 106 and thus positions itself to align with the landing target 106 such that the conical receptacles 142 are aligned with the conical pins 104 on the landing station 100. The drone 140 is considered to be in the correct position when the conical receptacles 142 are within a predefined radius or area (a predetermined tolerance level in the form of a radial limit 800 - see, for example, Figure 8) which is derived from the diameter D1 of the base of the conical receptacles 142.

[54] It will be understood that the Al can be calibrated for a camera on a drone that is not centred on the drone.

[55] Furthermore, it will be understood that the processing and Al described above may be performed by the computer 144 of the drone 140, the computer 108 of the landing station 100 or by a cloud computing environment.

[56] Upon completion of the second step, the conical receptacles 142 of the drone 140 are positioned above (approximately 200mm, for example) the apex 104a of the conical pins 104 and the third and final step of the landing process may be completed. [57] In the third step, the drone 140 is mechanically guided to land on the landing station 100 through the coupling assembly comprising the conical pin 104 and the conical receptacles 142.

[58] During the third step, once initial alignment of the conical pins 104 and conical receptacles 142 is achieved as described above, the drone 140 maintains alignment by assessing and adjusting to various factors (such as gusts of wind, eddy currents from the downdraft of the drone 140, etc.). In this regard, the drone 140, in some embodiments, may also determine or calculate, and assess velocity (including both magnitude and direction) and yaw (rotation) of the drone 140.

[59] As an example, if the drone 140 detects that its rotational position (yaw) is misaligned with the conical pins 104 by determining whether the yaw of the drone 140 is within a yaw angle tolerance limit. If the yaw of the drone 140 is outside the yaw angle tolerance limit, the drone 140 will rotate until the landing target 106 is aligned. In one embodiment, the drone 140 may use a target overlay that is a copy of the landing target 106 on the camera 150 that must align with the landing target 106 within a predetermined tolerance level. Preferably, the predetermined tolerance level allows the drone 140 to deviate from perfect (or acceptable) alignment by a few centimetres. As noted above, the accuracy is determined by the diameter of the opening of the conical receptacles 142. The larger the diameter, the greater amount of inaccuracy that can be tolerated.

[60] Determining and assessing velocity is useful for two reasons. Firstly, when adjusting the conical receptacles 142 for alignment in the initial phase of the landing procedure, it is helpful to determine speed and direction to ensure that the landing point is not overshot by an unnecessary adjustment in a particular direction (which may be the right or wrong direction). In this manner, velocity commands are provided to the drone 140 to ensure the drone 140 is correctly positioned over the landing target 106.

[61] Secondly, accounting for velocity allows compensatory movements to be made in response to environmental factors (such as wind) to maintain the alignment of the concial receptacles 142 with the conical pins 104 as the drone 140 descends for landing.

[62] In an example, the drone 140 determines its current velocity (including one or both of magnitude and direction) and adjusts its x, y (horizontal) position to centre the landing target 106 and/or adjust the position of the conical receptacles 142. For example, if the drone 140 is at a position of 50mm, 50mm (relative to the landing cone tip which is at 0,0).

[63] In another example, if the drone 140 detects that the landing target 106 is not centred, the drone 140 will adjust its x,y (i.e. horizontal) position until the landing target 106 is centred.

[64] In yet another example, if the drone 140 detects that the landing target 106 is too small in the image captured by the camera 150, the drone 140 will adjust its z (i.e. vertical) position until the landing target 106 is the right size.

[65] In another embodiment, a position vector 810 and a velocity vector 820 of the drone are used. The position vector establishes the position of the drone relative to the conical pin of the landing target. The apex 104a of the conical pin 104 is shown in Figure 8 along with the current position 801 of the drone 140. A future position of the drone is also calculated from the velocity (the future position 830) and comparing the future position 830 of the drone to a second predetermined tolerance level (indicated by the dotted line). If the position of the drone is within the second predetermined tolerance level, landing of the drone to engage the first coupling with the second coupling continues. If the position of the drone is outside the second predetermined tolerance level, landing of the drone to engage the first coupling with the second coupling may be paused and the position of the drone adjusted to re align the first and second couplings.

[66] It will be understood that calculating the future position of the drone may include calculating a future position of the first coupling of the drone. Furthermore, the second predetermined tolerance level may be equal or different to the predetermined tolerance level.

[67] In some embodiments, the first coupling is a dome, hemispherical, a square- based pyramid, a pyramidal frustum or a conical frustum and second coupling is a reciprocally shaped receptacle configured to receive the first coupling.

[68] The drone 140 slowly reduces thrust and descends towards the landing station 100. Due to the narrow width of the apex 104a of the conical pins 104 relative to the wide opening 142b of the conical receptacles 142, any centimetre-level inaccuracy is overcome and thus irrelevant.

[69] Due to the preceding positioning steps, the apex 104a of the conical pin 104 will be within the opening of the conical receptacle 142 so that the apex 104a impacts the angled internal wall of the conical receptacle 142 which then guides the apex 104a of the conical pin 104 towards the apex 142a of the conical receptacle 142.

[70] In some embodiments, the drone 140 will disable any algorithms for monitoring and adjusting x,y positioning to avoid the drone 140 attempting to compensate for any movement induced by the guiding forces imparted by the contact between the conical pins 104 and the conical receptacles 142. The drone 140 can continue to monitor its vertical positioning to compensate for any errors in vertical movement and alignment. For example, if the drone 140 has calculated a vertical movement of 10cm downwards towards the landing station 100 but, instead, the drone 140 descends 50cm, the drone 140 may be configured to invoke an abort operation to reattempt the landing process.

[71] In an embodiment, the coupling assembly also includes a locking assembly for securing the first coupling to the second coupling. This provides stability and security to the drone once it is docked preventing the drone from being lifted from the landing station by strong winds or theft. In one embodiment, shown in Figure 6, the locking assembly includes a locking pin 170 in the first coupling (such as the conical pin 104) and a cavity 172 in the second coupling (such as the conical receptacle 142) for receiving the locking pin 170 therein. Once the drone 140 has landed, the locking pin 170 may automatically extend from within a cavity 174 within the coupling that stores the locking pin 170 and engage the cavity 172 to secure the first coupling to the second coupling.

[72] In some further embodiments, the coupling assembly includes an inductive charging system in the form of a resonant inductive charging system. In such embodiments, the first coupling and the second coupling may have electrical coils 180 (see Figure 7) therein for wireless charging when the drone 140 is docked at the landing station 100.

[73] In one specific example (that will be understood as not limiting), the drone 140 executes the following algorithm to execute a successful landing and docking manoeuvre. An example of this algorithm as pseudocode can be seen in Figure 9.

[74] Firstly, the drone 140 moves into a hover position such that the drone 140 is centred in the x, y plane over the landing platform and is a height (e.g. 200mm) above the conical pins 104. [75] The rotation (yaw) of the drone 140 is determined and assessed on whether the rotation is within an acceptable limit. If not, the rotation of the drone 140 is adjusted to be within the acceptable limit.

[76] From the position in the x, y plane, a radius and angle of the drone 140 relative to the landing target 106 is calculated.

[77] Next, using the calculated radius and angle, it is determined whether the radius if within a first radial limit (radial_limit_1 of Figure 9). As an example, if the diameter of the foot of the drone (the conical receptacles 142) is 50mm, then a radial limit of 10mm may be set, which is well within the 50mm diameter of the foot of the drone 140.

[78] If yes, the instantaneous velocity vector (including both magnitude and direction) is calculated and a position of the drone 140 at future time t _n is calculated based on the current estimated position of the drone 140 and the instantaneous velocity vector.

[79] Using the estimated position of the drone 140 at t _n , it can be determined whether the position of the drone 140 at t _n is within a second radial limit (radial_limit_2 of Figure 9). This second radial limit may be the equal to the first radial limit or a unique, secondary radial limit different from the first radial limit.

[80] If yes, then the landing can commence.

[81] Embodiments of the invention described above allow a drone to return to a docking station accurately. This ensures the drone can performs any tasks requiring it to leave the docking station without concerns for the drone not being able to return to the docking station again.

[82] The word “drone”, as used herein, shall be understood to refer to any autonomous and/or semi-autonomous air vehicle. [83] In this specification, adjectives such as first and second, left and right, top and bottom, and the like may be used solely to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where the context permits, reference to an integer or a component or step (or the like) is not to be interpreted as being limited to only one of that integer, component, or step, but rather could be one or more of that integer, component, or step, etc.

[84] The above detailed description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The invention is intended to embrace all alternatives, modifications, and variations of the present invention that have been discussed herein, and other embodiments that fall within the spirit and scope of the above described invention.

[85] In this specification, the terms ‘comprises’, ‘comprising’, ‘includes’, ‘including’, or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed.

[86] Throughout the specification and claims (if present), unless the context requires otherwise, the term “substantially” or “about” will be understood to not be limited to the specific value or range qualified by the terms.