CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of the filing of U.S. Provisional Patent

Application No. 63/308, 835, entitled “APPARATUS AND METHODS FOR AQUATIC DATA

COLLECTION”, filed on February 10, 2022, the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention (Technical Field)

The present invention is related to low cost, lightweight, high speed uncrewed surface and subsurface vehicles for aquatic data collection, payload delivery, water quality monitoring, and other purposes. The vehicles can be deployed in pods of a plurality of vehicles, preferably all controlled by a single operator, that enable rapid large scale data collection across a wide area. The small vehicle size makes them ultraportable and able io be used in difficult to access areas. The vehicles can be launched from almost anywhere, including the surf zone, riverbank, dock, or a watercraft of almost any type.

Background Art

Note that the following discussion may refer to a number of publications and references.

Discussion of such publications herein is given for more complete background of the scientific principles and is not to be construed as an admission that such publications are prior art for patentability determination purposes.

SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)

An embodiment of the present invention is a mass inside the aquatic vehicle that is movable with respect to a vehicle hull; and a first compressive device configured to compress under a weight of the mass when the vehicle is oriented sufficiently vertically, and decompress when a more horizontal orientation of the vehicle reduces the force acting on the compressive device due to the weight of the mass; wherein a powered device is not utilized to move the mass relative to the vehicle hull. The compressive device preferably comprises a spring or flexible tubing. The mass preferably comprises one or more batteries which are preferably replaceable without requiring a tool. A second compressive device preferably located rearward from the first compressive device dampens the mobility of the mass when the aquatic vehicle is in large waves or currents. The first compressive device preferably comprises a spring and the second compressive device preferably does not comprise a spring. During forward motion of the aquatic- vehicle the mass is preferably disposed toward the front of the aquatic vehicle, thereby orienting the aquatic vehicle more horizontally. When the aquatic vehicle is vertically oriented the mass is preferably disposed toward the aft of the aquatic vehicle, thereby stabilizing the aquatic vehicle. The aquatic vehicle is preferably capable of traveling on or under a water surface and diving in a vertical orientation. The aquatic vehicle is preferably capable of traveling on the water surface at a speed greater than approximately 6 knots, more preferably greater than approximately 10 knots. The aquatic vehicle preferably comprises wings which maximize stable planing performance of the aquatic vehicle at a speed greater than approximately 6 knots. The wings preferably enable straight vertical alignment when the aquatic vehicle undergoes diving in a vertical orientation. The wings preferably comprise wing sections connected fo a hull unit and forward wings. The aquatic vehicle is preferably portable.

Another embodiment of the present invention is a method of operating an aquatic vehicle, the method comprising: a weight of a mass compressing a first compressive device while the aquatic vehicle is in an approximately vertical orientation: a vehicle motor producing a forward throttle; orienting the vehicle more horizontally; and moving the mass forward in the aquatic vehicle, thereby enabling the first compressive device to decompress and increasing the horizontal orientation of the aquatic vehicle; wherein the moving step is not performed using a powered device. The method preferably further comprises reducing a forward velocity of fhe aquatic vehicle; moving the mass rearward in the aquatic vehicle, thereby orienting the aquatic vehicle more vertically: and the weight of the mass compressing the first compressive device, preferably stabilizing the aquatic vehicle in an approximately vertical orientation. Such method preferably comprises the vehicle diving in a vertical orientation. The method preferably comprises dampening mobility of the mass when the aquatic vehicle is in large waves or currents. The dampening step is preferably performed by a second compressive device disposed in the vehicle rearward from the first compressive device. The method preferably comprises the vehicle traveling approximately horizontally on or under a water surface, optionally comprising the vehicle traveling on the water surface at a speed greater than approximately 6 knots, and preferably greater than approximately 10 knots.

Another embodiment of the present invention is an aquatic vehicle comprising a first hull section comprising a first threaded portion; a second hull section comprising a second threaded portion configured to mate with the first threaded portion; and a switch connected to one or more electronic components; wherein when the first hull section and second hull section are fully twisted together the first threaded portion forms a watertight seal with the second threaded portion and the switch activates the electronic components; and wherein the first hull section and second hull section are configured to enable a user to assemble them without the use of a tool. The first hull section is preferably a forward hull section and the second hull section is preferably an aft hull section. The watertight seal can preferably withstand a pressure of approximately 435 PSI. The watertight seal is preferably produced by the compression of two or more O-rings seated in grooves in either the first threaded portion or the second threaded portion. The switch optionally comprises a reed switch on the first hull section and a magnet on the second hull section configured so that when the first hull section and the second hull section are fully twisted together the magnet is sufficiently close to the reed switch to activate the reed switch. When the first hull section and the second hull section are sufficiently partially twisted together the first threaded portion preferably forms a water resistant seal with the second threaded portion. Such water resistant seal is preferably produced by the compression of one O-ring seated in a groove in either the first threaded portion or the second threaded portion. The water resistant seal is preferably sufficient to prevent water at a depth of less than approximately ten meters from entering the interior of the aquatic vehicle. A notch is preferably configured to be engaged when the first hull section and the second hull section are sufficiently partially twisted together, thereby indicating to the user that the water resistant seal has been formed.

Another embodiment of the present invention is a system for attaching one or more payloads to an aquatic vehicle, the system comprising one or more ports on a hull of the aquatic vehicle, each port comprising a first feedthrough to an interior of the aquatic vehicle and a first mating surface surrounding the first feedthrough; one or more payload housings each comprising a second mating surface configured to mate and form a watertight seal with one of the first mating surfaces, a second feedthrough, and a paytoad cavity; and one or more blanking caps each configured to mate and form a watertight seal with one of the first mating surfaces. The first mating surface preferably comprises a groove for seating an O- ring. The payload housings and the blanking caps are preferably each configured to bolt or screw to one of the ports. The payload cavity is preferably configured to receive and attach a particular payload such that a payload cable extends through the second feedthrough. The payload preferably comprises a sensor and the payload cable comprises a sensor cable preferably configured to attach to one or more electronics components within the aquatic vehicle. The payload cavity is preferably configured to be filled with epoxy after payload is attached to the payload cavity and the payload cable exits the second feedthrough. The aquatic vehicle is preferably capable of comprising any combination of payload housings and blanking caps when in use. A payload housing is preferably attachable to a port in a plurality of orientations relative to a hull of the aquatic vehicle.

Another embodiment of the present invention is an aquatic vehicle comprising one or more removable legs attached to the aft end of the aquatic vehicle, wherein the one or more legs are configured so that, when the vehicle collides with an object or the floor of an aquatic body, one or more of the legs break before a hull of the aquatic vehicle is damaged. The one or more removable legs are preferably sufficiently long to prevent components of a propulsion system on the aft end of the aquatic vehicle from contacting the floor of the aquatic body. The one or more removable legs are preferably sufficiently long to prevent a propulsion systems on the aft end of the aquatic vehicle from ingress of debris such as sand, rocks, and/or seaweed on the floor of the aquatic body. The one or more removable legs preferably provide a stable platform to support the aquatic vehicle on the floor of the aquatic body. Each leg is preferably connected to a standoff adapter which is connected to the hull of the aquatic vehicle. Each leg is preferably threaded and screws together with a threaded portion of a standoff adapter. Each leg preferably comprises nylon and each standoff adapter preferably comprises stainless steel. Each standoff adapter is preferably removable from the hull of the aquatic vehicle.

Another embodiment of the present invention is an aquatic vehicle comprising one or more control surfaces; and one or more removable protectors that at least partially surround at least one of the one or more control surfaces, wherein each protector is configured to be damaged from an impact or collision before the corresponding control surface is damaged. The control surfaces preferably comprise one or more elevators and a rudder. Each of the one or more removable protectors preferably comprises a recess for receiving an edge or other portion of the corresponding control surface. The one or more removable protectors preferably comprise nylon.

Objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a part of the specification, illustrate the practice of embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating certain embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

FIG. 1 is a schematic of an embodiment of a vehicle of the present invention.

FIG. 2 is a schematic of an embodiment of a tool-free vehicle access system of the present invention.

FIG. 3 is an enlarged view of the tool-free vehicle access system.

FIG. 4A is a top view of the tool-free vehicle access system.

FIG. 4B is an enlarged view of Section A-A of FIG. 4A.

FIG. 5A is a bottom view of the forward section of the vehicle,

FIG. 5B is a bottom view of the aft section of the vehicle.

FIGS. 6A-6B are two views of the water wings of the present in vention. The aft hull section is not shown.

FIG. 7 is a top view of the aft hull section of the vehicle showing the location of sacrificial control surface protectors and vehicle control surfaces of the present invention.

FIG. 8 is a magnified view of an embodiment of a sacrificial control surface protector.

FIGS. 9A and 9B are top and bottom view, respectively, of an embodiment of the vehicle of the present invention showing blanking caps and expansion pods attached to the vehicle expansion ports. FIG. 10 is a top view of an embodiment of an expansion port of the present invention.

FIG. 11 is an isometric view of an embodiment of a blanking cap of the present invention.

FIGS. 12A-12D are top, isometric, bottom, and exploded isometric views of an embodiment of an expansion pod of the present invention.

FIG. 13A shows the vehicle tail assembly with four sacrificial vehicle standoff assemblies, each comprising a standoff adapter that connects a standoff to the vehicle hull.

FIG. 13B is a schematic of an embodiment of a sacrificial vehicle standoff assembly of the present invention.

FIGS. 14A-C are schematics illustrating the high speed surface, sub surface, and vertical profile transit modes of operation respectively of an embodiment of the present invention.

FIG. 15 is an exploded view of an embodiment of the passive weight transfer mechanism of the present invention.

FIG. 16 is a bottom view of the passive weight transfer mechanism of FIG. 15 with the weight transfer carriage and battery housing removed.

FIG. 17 is a side view of the passive weight transfer mechanism of FIG. 15.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Embodiments of the present invention are small, lightweight, high speed aquatic vehicles than can be deployed in a pod for data collection, payload deliver, or other uses. A hub is preferably used to host the graphical user interface (GUI) and communications system, thus enabling wireless programming, control, data download and status monitoring of the vehicles of the present invention. The on-board computing element preferably hosts real time embedded open source software that controls ail aspects of the vehicle's operations and behaviors. This software interfaces with the hardware, electronics and other software and firmware drivers on the vehicle that provide navigational, internal and external communications, motion and speed controls.

The vehicles of the present invention preferably comprise a navigation system consisting of a GPS providing positional accuracy and an Inertial Measurement Unit (IMU) and compass for direction, acceleration and velocity. The vehicle’s dynamic control is preferably provided by a rudder, two elevators and a propeller that all work in combination with each other, preferably using proportional integrative and derivative (PID) loops, to achieve stable motion in all modes of transit. The propeller is preferably driven by a brushless DC motor that has a shaft connected to the propeller going through a watertight sealing assembly. Sensors that can be internal or external to each vehicle collect aquatic and other environmental data, which is preferably logged on the vehicle’s on board memory storage system. This data can be retrieved wirelessly for data management or processing. The system can be powered using Li-ion rechargeable battery cells and/or non-rechargeable primary battery cells. The vehicles of the present invention preferably comprise an optical beacon at or near the tip for hazard marking and recovery, a navigational package, an RF antenna for real time data exchange, plug and play sensor packages, a high efficiency propulsion system, an anti-snag hull profile, and a high performance computing element.

The forward section of the vehicle’s hull preferably comprises an extruded plastic or composite material tube which houses the majority of the system electronics, together with 3D printed nose and rear attachment assemblies. The aft end, which preferably houses the motor controls and actuators, preferably comprises 3D printed nylon multi jet fusion (MJF) parts. Planning a data collection mission can be completed in advance via the GUI and then loaded wirelessly onto each vehicle, thereby enabling autonomous or remote controlled data collection missions. Vehicle-collected data can be transmitted to the hub, wh ich can be shore based or vessel based, for real time data analysis. Alternatively, when the vehicle is in wi-fi range ail data sets can be rapidly downloaded into a database hosted on the hub. Once the mission is complete, the vehicles will preferably autonomously return to a defined recovery point. The GUI is preferably hardware agnostic and preferably has advantages including: simple-to-use mission planning suite, real-time system and vehicle status, user-configurable maps, automated survey planning, real-time data overlays, and automatic or manual return to home (RTH), enabling user training to be completed in less than eight hours.

In one or more embodiments of the present invention, certain vehicle parameters are: ♦ Weight: less than approximately 9 lbs ♦ Main Body Length: less than approximately 40 inches ♦ Main Body Diameter: less than approximately 3 inches ♦ Speed: greater than approximately six knots, up to approximately ten knots (or higher) ♦ Dive Depth Max: greater than approximately 50 m, up to approximately 100 m ♦ Dive Depth Min: less than approximately 1 m ♦ Range: surface transit greater than approximately 10 km ♦ RF Communications - Real Time Updates: 900 Mhz ♦ RF Communications - Wireless Data Download: 2.4 Ghz Wi-Fi ♦ Power: 2 x li-ion batteries, each less than 100 watt-hours (approximately 66 Wh) ♦ Sensor Options: temperature, depth, conductivity, dissolved oxygen, turbidity, pH, water sampler, hydrophone, other aquatic sensors

Some preferable rationales for these parameters are set forth in Table 1 below.

Table 1 : Parameter Rationales

Some of the general characteristics of one or more embodiments of the present invention are listed in Table 2.

Table 2: General Characteristics

For autonomous radio communications, all missions are preferably executed from start to finish without user intervention. Radio communications are preferably used to load the vehicles with the mission plan, but not while the mission is executing. While the vehicles are within range they will preferably appear as active vehicles on the GUI. The vehicles moving out of radio communications range during this mission will not impact the data collection integrity or the mission plan. When vehicles are out of communications range the user will preferably see the last know position and status. The waypoints the vehicles will be transiting to will preferably be displayed on the map as planned. When the vehicles return to within communications range they will preferably reappear as active vehicles on the GUI. if the hub is within radio range of vehicles, the user can change the mission tasking by sending a new mission to the vehicles. If the vehicles move out of communications range before the retasking upload has been completed, they will preferably stop executing the preplanned mission and move back to the last position they were ate when they had successful radio communications so that the mission update can be continued. When the new mission has been uploaded the new mission will be executed. If the user is within radio range of a vehicle, they can alternatively take control of a single vehicle using helm control. Mission tasks can be initiated from the GUI for a vehicle being directly controlled. If a directly controlled vehicle moves out of communications range, the vehicle will preferably stop and return to the last position the vehicle had with successful radio communications. When the vehicle is released from being directly controlled, the option to return to home or continue with its preplanned mission is preferably presented to the user. A new preplanned mission can be sent to a directly controlled vehicle, at which point the vehicle will preferably be automatically taken out of direct control mode to execute the preplanned mission. Any method of remote communication besides radio may alternatively be used.

For some applications the vehicle may be operated in stealth mode, during which the vehicles will not transmit radio communications for the duration of the mission and will not appear as active vehicles on the GUI, The optical beacons will not be enabled. The waypoints the vehicle will be transiting to will preferably be displayed on the map as planned. When the vehicles return to the recovery point the user has the option to initiate communications to enable recovery and review vehicle status. The system of the present invention is preferably a platform that is multi sensor configurable. It can be fitted with any sensor that is small enough, and with the market moving towards miniaturization at an ever-increasing pace the number of applications will grow significantly. Simply by adding different sensors, behaviors and payloads, the present invention can address multiple applications and mission types, including but not limited to environmental characterization, mobile Conductivity Temperature Depth (CTD) sensing, pressure measurement, sound velocity profiles, bathymetry and botom type assessment, hazard and channel marking, port security and diver intervention, hydrologic and environmental characterization, rapid environmental assessment, water quality data collection, testing, and sampling, including but not limited to dissolved oxygen, pH, carbon dioxide, phosphates, turbidity, and water sampling, passive acoustic monitoring, marine mammal monitoring, and payload delivery (towed or on board).

Embodiments of the present invention can be used to perform a variety of mission types, including but not limited to: ♦ Waypoint Mission: single or multiple discrete waypoints are set for the vehicles to carry out defined mission tasks. These waypoints and tasks can be chosen via the GUI or uploaded via a file. One example is: go to A, dive to 10 meters, go to B, dive to 10 meters, return to home; ♦ Station Keeping (Hazard or Safe Lane Marking): this is a special case of the Waypoint Mission with only one destination per vehicle: ♦ Optimized Survey Mission: a survey area is defined for the vehicles to carry out defined mission tasks. The system preferably calculates the optimal survey pattern based on the quantity of vehicles and programs each vehicle with a defined route to execute the mission. For example, execute 20 meter water depth dives at a grid resolution of 10 meters within a polygon (user defined), and upon mission completion return home; and ♦ Optimized Station Keeping (Hazard or Safe Lane Marking): this is a special case of the Optimized Survey Mission where the vehicles will station keep along the survey area’s perimeter.

Mission tasks include: ♦ Data Acquisition and Measurement: the vehicle preferably always logs data from the CTD, but for custom sensors a measurement can be programmed to trigger at a specific time, GPS coordinate, or depth; ♦ Dive: the vehicle will descend based on user defined depth increments, maximum depth, and dwell time. One example is: dive to a max depth of 10 m at 1 m increments, holding for

10 secorsds at each increment, if the vehicle hits the bottom, the deceleration of the bottom contact will preferably be recorded by the system and compared with results in a look-up table to determine the most likely bottom type. Preferably the motors will turn off after bottom detection and the vehicle will float back to the surface. The motors will preferably engage if the vehicle doesn't detect a risirsg motion after time to free itself. The user cars set a flag to dictate whether the vehicle should hold onto the bottom or return right away. ♦ Surface Drift: the vehicle will go to a position and turn off its propulsor for a user defined time. For example, the vehicle is programmed to go to position x and surface drift for 30 seconds. Upon completion, it will preferably enter station keeping mode awaiting the next command. Note that this is simply a Dive with a water depth of Q m. ♦ Station Keep: the vehicle will go to a position and station keep, using the propulsor and control surfaces to maintain that position until a new command is received. ♦ Return To Home: the vehicle will transit directly (line of sight) to the launch point or some other user-defined return to home position. This may trigger via a command from the user, when a certain vehicle state is reached (low battery) or be a final step in a mission.

The following tables show examples for various use cases for embodiments of the present invention.

Table 3: Waypoint Mission Use Case

Table 4: Optimized Survey Mission Use Case

Table 5: Generic or Optimized Survey (Autonomous User Retaskinq) Mission Use Case

Table 6: Single Vehicle Remote Control Use Case

Table 7: Survey Mission to Single Vehicle Remote Control Use Case

Tabie 8: User-Initiated Return to Home Use Case

A diagram of an embodiment of the vehicle of the present invention is shown in FIG. 1 . The vehicle preferably comprises one or more standoff batons 10, high speed water wings 20, optional nose corse 25, plug and play expansion pods 30, and sacrificial elevator protectors 40. The forward and aft vehicle sections of the vehicle hull are preferably 3D printed in nylon using the MJF process; however, they may alternatively comprise alternative materials, for example carbon fiber, that are of equal or superior characteristics (such as the ability to withstand pressure at depth) and do not substantially increase the overall weight of the vehicle. More detailed descriptions of embodiments of certain parts of the vehicle of the present invention follow below. A vehicle of the present invention may comprise one, more, or all of any of the following features and structures in any combination. Tool-less watertight vehicle access system

With typical vehicles opening a vehicle requires a took which is easily lost at sea. Furthermore, most vehicles also need a magnet, electrical shorting plug, or other device to turn the vehicle on without having to access the internal electronics of the vehicle. This device is also frequently forgotten or lost. To solve these problems, the tool-less watertight vehicle access system of the present invention, an embodiment of which is shown in FIGS. 2, 3, 4A, 4B, 5A, and 5B, preferably utilizes a twist-to-close, twist- to-open locking design that preferably incorporates an integrated power switch. By inserting vehicle rear or aft hull section 54 into vehicle forward hull section 52, then twisting the vehicle, internally threaded female receptacle 50 attach to externally threaded male connector 60 and pull the two halves of the vehicle together, which together with preferably dual O-ring seals creates a watertight seal that can preferably withstand pressures greater than about 100 pounds per square inch (PSI), more preferably greater than about 150 PSI, and even more preferably greater than about 435 PSI, or other pressures that the vehicle will encounter at depths of 100 meters or more. Two O-rings 58 are preferably disposed in grooves on male connector 60 and are preferably greased prior to use. Any number of O-rings may be employed to provide sufficient watertightness for the depths expected. The final twist to lock rotation preferably activates an integrated power switch that turns the vehicle on. The reciprocal twist to open rotation preferably deactivates power switch and opens the vehicle. This system preferably does not require the use of tools, enabling rapid battery changes that can maintain a high usage / operational tempo.

When operating the access system, initially the vehicle is in two halves, which enables easy access to internal electronics and power printed circuit board (PCB) 45 and other internals of the vehicle. Reed switch 68 is preferably disposed within female receptacle 50, preferably glued to a 3D printed mount which is then screwed to female receptacle 50, but any mounting system may be used. Magnet 66 is preferably attached to male connector 60. Magnetic reed switch 68 preferably detects the magnetic field from magnet 66 and actuates the electronics when reed switch 68 and magnet 66 are sufficiently close. When fhe two halves of the vehicle are initially mated together, the vehicle is preferably watertight for shallow depths when the first O-ring is engaged, but at this stage the electronics are not yet powered on because magnet 66, preferably comprising neodymium, has not come close enough to reed switch 68. If fhe vehicle is left partially twisted together in this state, it may be kept on the deck of a ship or a dock where water may splash on the vehicle but will not be able to get inside the vehicle to damage the electronics. Notch 62 in threads of female receptacle SO mates with protrusion 64 on male connector 60, preferably aligning the vehicle sections and providing tactile feedback to the user to let them know that magnet and reed switch are not yet engaged, but that the vehicle is watertight. When the forward and aft sections of the vehicle are fully twisted together, reed switch 68 is brought close enough to magnet 66 for the vehicle to power on, and the second O-ring is engaged, enabling full submersion of the vehicle to withstand deep ocean depths. The friction fit of the engaged O-rings is preferably sufficient to keep the two halves of the vehicle mated together, but an optional locking mechanism may be added.

High Speed Water Planing Wings

Water wings 20 are preferably disposed on each side of the vehicle’s hull, as shown in FIGS. 6A- 6B. The wings may comprise different sizes, shapes, numbers and angular positionings around the hull to maintain performance when different size and shape sensors and payloads are used on the vehicle. The fully assembled wings are preferably greater than 45% of the vehicle's total length, but may be increased or decreased in size to enhance vehicle performance, for example in extreme nearshore surf zone conditions. The wing shape or size may be varied to accommodate alternative sensor and payload modifications. The wings’ shape and size are preferably designed using computational fluid dynamics (CFD) modeling to maximize stable high speed planing performance and control for surface and subsurface transits in a forward direction across a wide range of low and high operational speeds (e.g. greater than about 10 knots), as well as to maintain straight vertical alignment when conducting reverse vertical profile dives (tail-first). The wings preferably help prevent turning movements and help upon initial throttle. Water wings 20 preferably comprise two components attached to the main hull and preferably to each other: (1) center-hull 80 comprising integrated wing sections 85; and (2) forward wing 87. All bonding is preferably executed such that no gaps nor bubbles remain between the hull section and forward wings to maintain a polished finish, ensure the sections are completely watertight, and reduce fluid drag at the bonding locations. These components preferably comprise a 3D printed nylon using the MJF, but may alternatively comprise a higher performance material, such as a carbon fiber composite, to increase the wing durability, minimize the impacts of water absorption that can be a problem with 3D printed designs, decrease temperature changes on the wings, and reduce the overall weight of the wings. in alternative embodiments, all of the components (optionally including forward hull section 52) can comprise a fully integrated part that is printed or composited as a single component.

Sacrificial control surface protectors Control surfaces, such as elevators 47 or rudder 49, are used to manage the vehicle’s pitch, roll, and yaw angles during underwater transits, surface transits, or dives. The extremities of the vehicle and control surfaces are prone to damage during operational use, shipping, storing, and from accidents if improperly handled. Sacrificial control surface protectors 40 are relatively inexpensive, lightweight components that protect control surfaces from impacts that could change their alignment or render them inoperable. Recognizing that the extremities of the vehicle are prone to damage when dropped or in operational use, the sacrificial protectors absorb any impacts, and when damaged they can be simply be unscrewed (or otherwise easily removed) and replaced. As used throughout the specification and claims, a part that is “removable” and/or “replaceable” means that part is designed to be removed and/or replaced without having to partially or fully disassemble or repair the vehicle. When larger than normal impacts are registered at or near the control surface, sacrificial control surface protector 40 is preferably the first piece to fail. Sacrificial control surface protectors 40 are preferably 3D printed in nylon using the MJF process; this material (and any alternative material) is preferably sufficiently durable to absorb daily impacts, but soft enough to break when an abnormal impact occurs. Sacrificial control surface protectors 40 preferably surround the outer perimeter of the vehicle's control surfaces, preferably varying in shape and size depending on the size and shape of the control surfaces and vehicle they are designed for.

Sacrificial control surface protectors 40 each preferably comprise a recess for the corresponding control surface to notch into, thus providing mounting support as well as protection. FIGS. 7-8 show a sacrificial control surface protector 40. When assembling the vehicle, elevators 47 are preferably installed first. Next, sacrificial control surface protector 40 is attached to both elevator 47 and the tail housing, then screwed into the tail housing preferably using two hex head screws 43, although any attachment method that enables easy, rapid replacement may alternatively be used. Spares of sacrificial control surface protector 40 are preferably readily kept on hand. Plug And Play Watertight Expansion System

The mounting configuration of the plug and play watertight expansion system of the present invention allows any number and types of payloads, for example sensors, having variable form factors (size, weight, cost, etc.) to be installed onto the vehicle and/or replaced with an alternative payload with ease. The payload or payloads can be mounted in various locations and orientations on the vehicle without requiring the vehicle’s exterior to be modified in any way, and the system eliminates the need for a waterproof electrical connector on the exterior of the hull, lowering vehicle cost and maintenance requirements.

As shown in FIGS. 9A-12D, the system comprises one or more expansion ports 100 in the vehicle hull; in one embodiment an expansion port can be on the port side of the hull and another can be on the starboard side of the hull. Each expansion port 100 preferably comprises feedthrough 104 surrounded by mating face 107, to which expansion pod 30 or blanking cap 120 may be attached flush, forming a watertight seal. Expansion port 100 preferably comprises O-ring groove 102, preferably sized to allow for about 20%-25% compression of an O-ring when expansion pod 30 or blanking cap 120 is attached. Mating face 107 preferably comprises more screw holes 109 than are required to attach expansion pod 30 or blanking cap 120. For example, in the embodiment shown in the figures, three screws are sufficient, although in other embodiments any number of screws may be used. In this case mating face 107 comprises six screw holes 109, enabling expansion pod 30 to be attached in a variety of orientations. Particularly, by using twice the number of holes that mirror the three screw holes 112 in expansion pod 30, enable expansion pod 30 to be attached at either a 0° or 180“ alignment to the vehicle’s longitudinal axis, enabling the user to freely dictate where and in which orientation each payload will go.

Expansion pod 30 comprises cable feedthrough 115 which, when sensor pod 30 is mounted on mating face 107, aligns with port feedthrough 104, providing a direct route to the inside of the vehicle that can be used for connecting payload 110 to the internal electronics that are programmed for, for example, data collection. Expansion pods 30 are preferably 3D printed to the size and configuration needed to house the sensor or payload body and electrical connections, and preferably comprise a universal fit configuration to mating face 107, enabling a wide range of different sensor or payload types, shapes, sizes, and weights to easily be interchangeably attached to different vehicles. When installing payload 110, the payload cable is preferably pulled tautly through expansion pod 30, and payload 110 is secured within cavity 103 of expansion pod 30, optionally by screwing payload 110 into cavity 103 if both are threaded. The unfilled portion of cavity 103 surrounding the payload and cable is then preferably filled with epoxy through cable feedthrough 115 in expansion pod 30. This secures both the payload and cable into the pod and ensures a watertight fit. If a payload is located elsewhere on the vehicle, the payload cable can be fed through a custom fitted expansion pod, and is preferably epoxied inside the expansion pod to be watertight in a similar manner. The cable is then fed through port feedthrough 104 and preferably pulled tight. Expansion pod 30 is then secured to mating face 107, preferably using button-head hex screws 124, although any attachment method may be used. The payload cable within the vehicle is then connected to the vehicle's interior electronics.

If there is no need for an expansion port to have a payload attached, blanking cap 120 can be secured to that port instead of expansion pod 30. Blanking cap 120 preferably comprises a flat bottom designed to lie flush with mating face 107, a tapered top, and mounting screw holes 122 in the same configuration as screw holes 112 in expansion pod 30, Blanking caps 120 preferably do not comprise include a cable feedthrough. Blanking caps 120 ensure the vehicle will remain watertight without needing to populate all expansion ports 100 on the vehicle with an expansion pod 30.

Sacrificial Vehicle Standoffs

One or more (preferably four) bottom sacrificial vehicle standoffs 10 prevent contact of the rudder and propeller systems with the floor of the sea, river, or lake when the vehicle is diving vertically, minimizing damage to those components and reducing bottom debris (sand, rocks, seaweed, etc.) ingress into the propeller duct by maintaining a safe distance between the bottom and the propulsion system (propeller, duct, shaft, motor, etc.). They also provide a stable platform when the vehicle is commanded to remain on the bottom by continuing to create reverse thrust. Standoffs 10 are removeable and can be of any length, but they preferably protrude beyond any other part of the vehicle, and are preferably greater than about 2.5” to be compatible with different bottom types, such as rock, sand, shell, cobble, mud, or seaweed. For example, longer standoffs can be used in soft sand in which they will be embedded. The sacrificial vehicle standoffs preferably are able to withstand the force of collision with an obstruction or the bottom. Should the collision cause one or more of the standoffs to break, the performance and safety of the vehicle is unaffected, and the broken standoffs are able to be replaced upon recovery. The standoffs are preferably designed to break under torque stress, so that the standoff(s) will break before any damage is caused to the rest of the vehicle. Sacrificial vehicle standoffs 10 can also be used to alter the center of gravity (CG), center of mass (CM), and/or center of buoyance (CB) of the vehicle. This effect can be used to trim the vehicle (i.e, alter its longitudinal angle in the water) to account for varying payloads and operating environments. The standoffs can also be used as mounts to attach equipment and sensors to the vehicle. As shown in FIGS. 13A and 13B, each sacrificial vehicle standoff assembly 130 preferably comprises standoff 10, which is preferably cylindrical, and standoff adapter 135. Standoffs 10 preferably comprises nylon, but alternatively may comprise any material both strong enough to withstand the immediate impact of the vehicle encountering variable waterbody bottom surfaces and weak enough to break prior to causing harmful stress to the vehicle’s aft hull section 54, to which standoff adapters 135 are preferably attached. Standoffs 10 are designed to be detachable from standoff adapters 135 and are preferably sufficiently long to be able to break anywhere along the exposed section or directly within the corresponding standoff adapter. Standoff adapters 135 preferably comprise 316 stainless steel, but may comprise alternative materials that are corrosion resistant and of equivalent durability (i.e. stronger than the standoff itself)- The standoff adapter is preferably shorter in length than the corresponding standoff so that if the standoff collides with an obstruction, the standoff will break before the rest of the vehicle incurs any damage. The outer diameter of each standoff adaptor 135 is preferably slightly larger than the outer diameter of the corresponding standoff 10. Standoff adapters 135 preferably can be removed and replaced as needed. For example, should a standoff break flush within the corresponding standoff adapter, and/or can no longer be removed by itself from the standoff adapter, the entire sacrificial vehicle standoff assembly can be completely replaced. For ease of replacement, each standoff adapter 135 preferably comprises a male threaded end for screwing into a female threaded receptacle in aft hull section 54 and a female threaded end for receiving a male threaded end of standoff 10. However, any alternative method of attaching the standoff adapter to the vehicle hull and attaching the standoff to the standoff adapter may be used. For example, the standoff adapters could employ a clip In place of a thread to connect to the vehicle hull.

Operation and Passive Weight Transfer Mechanism

The three primary modes of operation of the vehicle of fhe present invention are high speed surface transit, subsurface transit, and water column vertical profile transit (dive mode), as shown schematically in FIGS. 14A-14C. The vehicle preferably comprises a hydrodynamic shape enabling it to skip on the surface during the high speed surface transit mode, and proceed underwater in subsurface transit mode, with minimum drag.

This multiple transit mode capability is preferably aided by a passive weight transfer mechanism, which is preferably used to passively change the angle of the vehicle with respect to its direction of travel, center of gravity (CoG), center of mass (CoM) and center of buoyancy (CoB) of the vehicle to aid vehicle control and stability during surface and underwater transits, dives, drifts, station keeping, or any vehicle mission/operational task. Unlike powered devices such as screw mechanisms, servos or variable buoyancy devices typically employed by aquatic vehicles, the present mechanism preferably uses only gravity and acceleration to transfer weight fore or aft. In the embodiment of the passive weight transfer mechanism shown in FIGS. 15-17, the vehicle’s internal electronics (not shown in these figures) may optionally be mounted to the top of the plate 200, while the bottom of plate 200 is preferably used fo attach both forward weight transfer mechanism 210 and aft weight transfer mechanism 220. Plate 200 preferably comprises carbon fiber, but any rigid, light weight material may be used. Plate 200 is preferably rigidly connected to the vehicle hull via chassis support bracket 202 and thus serves as the stationary component of the passive weight transfer mechanism, remaining secured within the hull while all moving components of the passive weight transfer mechanism are free to move. Chassis support bracket 202 is preferably attached to the forward end of plate 200.

Forward weight transfer mechanism 210 comprises toward attachment 211 and rear attachment 213 which are both attached to plate 200 (preferably via screws); fwo dowel pins 214; and two springs 216 each fed onto a first end of dowel pin 214. Dowel pins 214 preferably comprise 18-8 stainless steel, and springs 216 are preferably corrosion-resistant and preferably comprise zinc-plated music wire steel, but any durable and corrosion resistant materials may be used. Dowel pins 214 extend through and are atached to center adapter 212, and a piece of rubber tubing 218 is atached to the second end of each dowel pin 214. Rubber tubing 218 preferably comprises latex, although any similar compressive material may be used. As used throughout the specification and claims, the term “compressive device” means spring, rubber tubing, or any material or device that is capable of compressing when exposed to a force over a certain value and recovers its shape when such force is lessened below said certain value. Aft weight transfer mechanism 220 is preferably identical to forward transfer mechanism 210, except springs 216 are replaced by pieces of rubber tubing 228. Because aft weight transfer mechanism 220 is spring- free, it preferably provides enough dampening of the spring-loaded front section of the vehicle to prevent the inertial mass from being excessively mobile in harsh environmental conditions, such as being tossed around in large waves and in underwater currents. Weight transfer carriage 230 is then attached (preferably via screws) to center adapters 212 of both forward weight transfer mechanism 210 and aft weight transfer mechanism 220. The entire assembly is then atached to the hull, preferably via two screws that feed through chassis support bracket 202.

One or more inertial masses, which may comprise any object, but in this embodiment comprises two lithium ion batteries 235, are inserted into housing 240, which is then slid into weight transfer carriage 230. Clip 242 is preferably attached to the forward end of housing 240 and not only secures batteries 235 in housing 240 but also clips housing 240 to weight transfer carriage 230. The use of clip 242 preferably ensures that batteries 235 may be easily removed and replaced by sliding housing 240 out of weight transfer carriage 230 without the need for any tools. Thus batteries 235, housing 240, weight transfer carriage 230, center adapters 212, and dowel pins 214 can move with respect to the vehicle hull via springs 215 and rubber tubing 218, 228. The weight of the inertial mass and the spring constant of the spring can have any values but are chosen so that the passive weight transfer mechanism functions appropriately for each vehicle. Chassis support bracket 202, forward attachments 211 , rear attachments 213, center adapters 212, weight transfer carriage 230, housing 240, and clip 242 all preferably comprise MJF 3D-printed nylon, although other materials may be used for any or all of these parts.

With respect to a vehicle that comprises a long axis, typically extending from the nose of the vehicle to the tail of the vehicle, as used throughout the specification and claims, the terms “vertical orientation”, “vertically oriented”, and the like mean that the long axis of the vehicle is approximately perpendicular to a water surface (i.e. the nose of the vehicle is pointed approximately upward or downward), and the terms “horizontal orientation”, horizontally oriented”, and the like mean that the long axis of the vehicle is approximately parallel with the water surface, in operation, when the vehicle is at rest, it is preferably oriented approximately vertically (i.e, with the nose oriented approximately upward), in this orientation, the spring cannot overcome the force of the inertial mass, so the weight is disposed as far toward the aft of the vehicle as it can go. When the motor produces a forward throttle, the force vectors of the thrust, gravity, and buoyancy means that the center line of the vehicle transitions into a more horizontal attitude. As the vehicle moves and its nose orients more horizontally; i.e. more closely to its direction of travel, the compressive force of the spring overcomes the pulling force of gravity and the inertial mass slides towards the front of the vehicle. With the weight toward the front of the vehicle, the CoG and CoM are moved further forward and the CoB is moved backward, which makes the vehicle more horizontal than it would be if the weight didn't slide. The horizontal attitude improves surface transit by aligning the propeller with the direction of travel, increasing efficiency. When the vehicle stops, the lack of a thrust vector causes the inertial mass to slide toward the aft of the vehicle, moving the CoG and CoB rearward and thus orienting the vehicle more vertically than it would have been without the sliding inertial mass. In this configuration, the CoB is moved forward, and the further separation of the CoG from the CoB makes the vehicle stable when it is submerged vertically in the water and enables vertical profile diving.

Note that in the specification and claims, “about” or “approximately” means within twenty percent (20%) of the numerical amount cited. As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a functional group” refers to one or more functional groups, and reference to “the method” includes reference to equivalent steps and methods that would be understood and appreciated by those skilled in the art, and so forth.

Although the invention has been described in detail with particular reference to the disclosed embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover all such modifications and equivalents. The entire disclosures of all patents and publications cited above are hereby incorporated by reference.