Multi-axis actuated tailcone for autonomous underwater vehicles

Abstract

A multi-axis actuated tailcone for an autonomous underwater vehicle (AUV) is provided. The AUV includes a removeable, interchangeable drive module, active and passive roll compensation, and removeable and interchangeable shrouds and fins for optimizing hydrodynamic performance. The tailcone includes a hull having an exterior surface and defining a cavity. A motor may include a shaft disposed at least partially within the hull. A drive module may be disposed in the cavity. The drive module includes one or more drivers. A plurality of fins are disposed about an exterior surface of the hull. Each fin is coupled to one of the one or more drivers. A propeller assembly is coupled to the shaft and includes a shroud.

Description

MULTI-AXIS ACTUATED TAILCONE FOR AUTONOMOUS UNDERWATER VEHICLESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Patent Ser. No. 63 / 584,639, filed on September 22, 2023, the content of which is hereby incorporated by reference in its entirety7.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not Applicable.FIELD OF TECHNOLOGY

[0003] The described technology relates generally to underwater vehicles, more particularly to tailcone and aft section assemblies for propulsive and control mechanisms of autonomous underwater vehicles.BACKGROUND

[0004] Autonomous underwater vehicles (AUVs) have long been used by both military and scientific communities. Militaries often rely on underwater ordinance, such as torpedoes, and marine vehicles, manned and unmanned systems, when operating in ocean or underwater environments. Similarly, marine scientists often use AUVs to conduct experiments and collect for further study data and materials by towing a pay load or with directly attached, fixed sensors. These AUVs are often subject to size, weight and other operational constraints that present obstacles to efficient and cost-effective design and assembly.

[0005] Traditional AUVs include control surfaces such as rudders, elevators and the like to control the trajectory and route of the vehicle. Often, such control surfaces are contained in or on a tailcone assembly attached to an aft section of the vehicle. Traditional tailcones are limited in their overall capabilities and reliability.SUMMARY

[0006] Aspects of the present disclosure relate generally to a tailcone design for undersea systems, including autonomous underwater vehicles (AUVs), such as, for example, an Expendable Mobile Anti-Submarine Warfare Training Target (EMATT vehicle). Aspects of the disclosure provide systems and devices that may maintain control surfaces and propulsion within diametric constraints imposed on an overall system, including the size, weight, speed, control lifespan, and the like.

[0007] According to one aspect, an assembly may include a hull having an exterior surface and defining a cavity. A motor may have a shaft disposed at least partially within the hull. A drive module may be disposed in the cavity. The drive module may include one or more drivers. A plurality of fins may be disposed about the exterior surface of the hull. Each fin may be coupled to one of the one or more drivers. A propeller assembly may be coupled to the shaft. The propeller assembly may include a shroud.

[0008] The assembly may include, alone or in combination, one or more of the following features. The one or more drivers may include one or more servo motors. Each of the one or more drivers may include a gear assembly. Each gear assembly may be coupled to a fin shaft. The fin shaft may extend from the cavity through the exterior surface and coupled to one of the plurality of fins. The fins may be removeable. The propeller assembly may be interchangeable. The shroud may be interchangeable. The shroud may include a passive roll compensator. The drive module may be interchangeable. The drive module may further include a controller adapted to actuate the plurality of fins. The drive module may be adapted to provide active roll compensation by actuating one or more of the fins. The hull may define at least one port. The at least one port may be one of payload port, a power port, a communication port, a pressure compensation port, a multipurpose port, and a charging port. The motor may be waterproof and external to thehull. Each of the plurality of fins may be within a diameter profile of the hull. The hull may define at least one strain relief mount. The fins may actuate about an axis substantially perpendicular to a longitudinal axis of the hull. Each of the plurality7of fins is coupled to a shaft having a length less than a radius of the hull where the shaft is disposed through the hull.

[0009] According to another aspect, a tailcone assembly may include a hull defining a cavity7and a motor having a shaft disposed at least partially within the hull. A removeable drive module may be disposed in the cavity. The drive module may include one or more servo motors. Each of the one or more servo motors may provide control of three degrees of freedom. A plurality of fins may be disposed about an exterior surface of the hull. Each fin may be removably coupled to one of the one or more servo motors. A propeller assembly may be coupled to the shaft. The propeller assembly may include a shroud. A controller may be coupled to the motor and the one or more servo motors. The controller may be configured to drive the servo motors to direct the plurality of fins to provide active roll compensation.

[0010] According to another aspect, an autonomous underwater vehicle may include a nose, a body coupled to the nose, a controller, and a tailcone assembly in communication with the controller. The tailcone assembly may include a hull having an exterior surface and defining a cavity. A motor may have a shaft disposed at least partially within the hull. A drive module may be disposed in the cavity. The drive module may include one or more drivers. A plurality of fins may be disposed about an exterior of the hull. Each fin may be coupled to one of the one or more drivers. A propeller assembly may be coupled to the shaft. The propeller assembly may include a shroud.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The manner and process of making and using the disclosed embodiments may be appreciated by reference to the figures of the accompanying drawings. It should be appreciated that the components and structures illustrated in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principals of the concepts described herein. Like reference numerals designate corresponding parts throughout the different views. Furthermore, embodiments are illustrated by way of example and not limitation in the figures, in which:

[0012] FIG. 1 is an isometric rendering of a tailcone assembly according to one or more aspects of the present disclosure.

[0013] FIG. 2 is a side view of the tailcone assembly of FIG. 1, according to one or more aspects of the present disclosure.

[0014] FIG. 3 is a rear isometric view of the tailcone assembly of FIG. 1, according to one or more aspects of the present disclosure.

[0015] FIG. 4 is an exploded view of the tailcone assembly of FIG. 1, according to one or more aspects of the present disclosure.

[0016] FIG. 5 is a partial exploded view of the tailcone assembly of FIG. 1, according to one or more aspects of the present disclosure.

[0017] FIG. 6 is a front view and a rear view of the hull of the tailcone assembly of FIG. 1, according to one or more aspects of the present disclosure.

[0018] FIG. 7 is a side view of an autonomous underwater vehicle (AUV) fitted with a tailcone assembly, according to one or more aspects of the present disclosure.

[0019] FIG. 8 is a perspective view of an the AUV and tailcone assembly of FIG. 7. according to one or more aspects of the present disclosure.

[0020] FIG. 9 is a partial exploded view of an alternative embodiment of a tailcone assembly, according to one or more aspects of the present disclosure.

[0021] FIG. 10 is a series of data plots, according to one or more aspects of the present disclosure.

[0022] FIG. 11 is a is a diagram of an example of a controller, according to one or more aspects of the present disclosure.DETAILED DESCRIPTION

[0023] The detailed description set forth below, in connection with the appended draw ings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for providing a thorough understanding of the various concepts. It will be apparent to those skilled in the art. however, that these concepts may be practiced without these specific details. In some instances, well-known structures and components are show n in block diagram form in order to avoid obscuring such concepts.

[0024] Aspects of the present disclosure relate generally to a multi-axis (e.g., three- axis) actuated tailcone for an autonomous underwater vehicles (AUV) featuring a removeable, interchangeable drive module, active and passive roll compensation, and removeable and interchangeable shrouds and fins for optimizing hydrodynamic performance.

[0025] Known tailcones are limited in their overall capabilities and reliability. For example, some known tailcones rely on off-the-shelf components to achieve what is commonly referred to as ‘'Bang-bang” control, in which four flooded solenoids are used to push or actuate an acetyl pin against a plate causing the fins to rotate. When traveling in astraight direction, the solenoids turn off and the fins straighten themselves out. Accordingly, such systems lack an active roll control. Such systems are less expensive, however they do not offer compensation capabilities for active roll of the vehicle.

[0026] Other known tailcones use split rudders wi th external servo motors and a fixed shroud to enhance the performance of the vehicle. The external servos are filled with oil in order to compensate for pressures when submerged. Such systems are disadvantageous because the external servo motors often need to be replaced due to frequently leaking oil. In those situations, water may ingress, resulting in damage and failure of the controls, including the internal electronics, during operation. Many commercially available servo motors are described as “waterproof’; however, they are merely splash proof. This is due to a stretched and compressed gland or seal. The ingress protection (IP) ratings of these devices are insufficient for marine applications. For example, while IP68 is the maximum rating for the IP Standard (i.e., impermeable up to 13 feet of submersion for an indefinite period), most traditional servos are rated for IP67. IP67 devices are dust tight and have a watertight submersion maximum of between 15 centimeters (cm) and 1 meter (m) for 30 minutes.

[0027] Further, external waterproof servo motors come at several costs - namely size, weight, and price. Therefore, to improve reliability and reduce costs, if servos are the desired mode of actuation, the servos can be driven from a dry section with dynamic sealing surfaces which drive the control surfaces. Tailcones relying on truly waterproof or watertight servo motors or linear actuators, such that analog control can be achieved, are traditionally expensive and present significant challenges in keeping costs low and working within size constraints.

[0028] Aspects of the present disclosure provide for a cost-effective tailcone assembly that may be easily assembled and disassembled, may be adaptable to changing internal andexternal pressures underwater, and may further include a multi-purpose pay load assembly supporting a variety of applications and operations.

[0029] Aspects of the present disclosure provide a tailcone assembly w ithin such constraints while still accommodating scientific objectives and other functionalities. For example, government classifications dictating the size of such AUVs are derived from the classification of different ordinance systems and payloads launched from DoD vehicles, (i.e., torpedoes and autonomous submersibles).

[0030] According to one aspects of the present disclosure relate a three-axis actuated tailcone may include a removeable, interchangeable drive module in an unwetted section of the vehicle, active and passive roll compensation, and removeable and interchangeable shrouds and fins for optimizing hydrodynamic performance and stability. Aspects of the present disclosure further provide for a tailcone assembly that may be easily assembled and disassembled, may accommodate for changing internal and external pressures, and may further include multi-purpose payload support for a variety of applications and operations.

[0031] As described herein, aspects of the present disclosure provide a tailcone with an interchangeable drive module for actuating the control surfaces of an AUV. According to one aspect, a tailcone with at least three-axis control with at least three in-profile control surfaces is described. The tailcone may include modular ports for supporting a variety of payloads, including towing an acoustic payload, as well as interchangeable shrouds for passive roll compensation. The passive roll compensation may be tuned for an expected cruising velocity, which may also be supported by active roll compensation. The enumerated features described herein provide a tailcone assembly that is easy to assemble and maintain, is cost effective, can be used for vehicles with an extended lifetime (i.e.,non-expendable vehicles), and can be adapted to support a variety of scientific and military missions.

[0032] According to one aspect of the present disclosure, the tailcone design described herein may overcome the unique nature of underwater vehicle operation as well as several of the shortcomings of traditional tailcone designs. For example, it is important to provide a sealed environment inside of the tailcone such that internal components are not exposed to water, salt and other potential contaminants. Rubber seal glands need to be machined very' precisely, since vehicles may be rated to up to depths of 1000m or more, which may be up to lOOx more pressure than what humans endure in a normal atmosphere. Further, human interfaces may be disposed to the aft section of the vehicle and may be shrouded with a quick release cowling (FIG. 9) for manipulating or monitoring the electrical or physical states of the vehicle.

[0033] Aspects of the present disclosure further provide a tailcone assembly adapted to accommodate significant loads placed on the control surfaces. Loading on the fins of the tailcone may be distributed to the hull of the vehicle rather than the sealing gland and sealing surface disposed about the shaft of the fin. That is, in traditional tailcones when the fin actuates, without loading support, the drag and lift over the fin may squeeze or otherwise compromise the rubber seal and cause a leak or damage the seal. Some designs may avoid dynamic seals and use magnetic couplings instead. These couplings, however, may be limited to how much torque they can transfer through a hull wall, which needs to be thick to endure desired operating depths. Magnetic couplings are also expensive, difficult to manufacture and may interfere with the signal transmission within a vehicle.

[0034] Tailcones described herein may be designed and built to accommodate varying size constraints. According to one aspect, tailcone assemblies described herein may be for use with micro-AUVs, for which the diameter is typically less than 5 inches (in.). As oneexample, U.S. Navy A-Sized ordinance calls for a payload which can fit in a 5 in. sonobuoy launch tube. Accordingly , a properly constrained tailcone design, like those described herein, may include a propulsion mechanism and the actuators for driving control surfaces within a 5 in. diameter. While aspects of the present disclosure rely on such a size constraint, one skilled in the art will appreciate that other size constraints may be considered and other radii tailcone assemblies may be contemplated.

[0035] Streamlining fluid flow around the tailcone is another design consideration.When adding features such as pay load towing or other attachments to an AUV, there are limited places where such features can be implemented that would not disproportionately compromise the performance of the vehicle. According to one aspect, an ideal location for placing add-on structural features may be in the aft section, where features are less likely to compromise overall performance. When working with other requirements, such as granting control authority with control surfaces (fins) and the thruster, space may be limited.

[0036] Portability is another key factor in tailcone design. AUVs may be difficult to store and transport, since the fins protrude from the vehicle. Accordingly, AUVs often require specialized stands or equipment to deploy, reclaim, and stow the vehicle. The external nature of the fins may limit the placement of a vehicle and determine how it is stowed. For example, if a vehicle's core diameter is 5 in. fins are likely an extra 2 in. to 4 in., resulting in a profile diameter of 11 in.

[0037] Power transmission in AUV tailcones can be problematic also. Control surfaces are typically excited, or actuated, by servo motors, stepper motors, or linear actuators. Known waterproof servo and stepper motors are ven’ large and bulky, where they cannot reside outside of the vehicles within the intended size class. Further, as described above,many so-called ‘‘waterproof’ servos are not, in fact, waterproof and are susceptible to leakage and damage under pressure and over time.

[0038] Tailcone assemblies, which include detailed and precisely described features, may be hard to manufacture for the conditions in which they serve. They must be corrosion resistant, compressive resistant (for depth), produce a streamlined fluid flow, and contain watertight features.

[0039] Roll compensation is yet another design hurdle. A thruster of an AUV may generate a torque around the vehicle which may cause the vehicle to roll about its longitudinal axis. How much the vehicle rolls may be related to the revolutions per minute (RPM) of the propeller, and therefore the speed of the vehicle. Compensating for the roll may be accomplished with either passive or active compensation. To passively compensate for the roll that inevitably occurs, a shroud / stator system may be designed for a specific vehicle and for a specific nominal cruising speed. According to one aspect, the shroud may include features, such as one or more stators, to assist in passively counteracting the roll on the vehicle. To actively compensate for unwanted roll, a tailcone assembly may include at least three degrees of freedom to address climbing / descending to depth, turning within the longitudinal / latitudinal plane, and controlling the roll about the vehicle’s longitudinal axis. The necessary control over three degrees of freedom may require at least three actuators. Reliance on purely active roll compensation, however, results in the fins not being hydrodynamically streamlined or in an optimal configuration. Accordingly, the assembly and control systems may waste energy overcoming the induced drag to compensate for roll.

[0040] Aspects of the present disclosure provide a tailcone assembly according to the above considerations. Referring generally to FIGS. 1-6, an exemplary tailcone assembly100 is shown. The tailcone assembly 100 may include a motor 10 and a flange 12 coupledto a hull 3. The flange 12 may be coupled to the hull 3 by an aft threaded connection, by one or more fasteners, or another connection mechanism. According to one aspect, the flange 12 may include a forward threaded connection adapted to couple the tailcone assembly 100 to a mating threaded connection on an AUV (not shown). According to one aspect, the flange 12 may be made from a suitable metal or plastic. The motor 10 may be, according to one aspect, a direct current (DC), brushed motor adapted to receive power from a battery' or other power source housed in the AUV. The motor 10 may be coupled to or include a motor shaft 14 (FIGS. 4, 5) extending through the hull 3 and adapted to drive a propeller 18. A lip seal system may be implemented around the motor shaft 14.Alternatively, an outboard (e.g., external) waterproof brushless motor w ith no lip seal may be used instead. The motor shaft 14 may drive the propeller 18, rudders and elevators (not shown) as is known in the art.

[0041] The interior of the hull 3 may be sized and shaped to accommodate a drive module 2, a power transmission stack, such as gear assemblies 54, and a number of ports 60, as described below. The exterior of the hull 3 may be shaped to increase hydrodynamics and reduce drag. The hull 3 may define one or more strain relief mounts 40 (FIG. 3) adapted to redirect and allow the flow of w ater about the hull 3, thereby reducing the strain on a payload.

[0042] One or more fins 5 may be disposed about the exterior of the hull 3. The fins 5 may be articulable about the hull 3 to assist in roll compensation, depth control, steering and otherwise adjusting course for the AUV. According to one aspect, the fins 5 may extend from the tailcone, yet be within the widest diameter of the hull 3. According to one aspect, each fin 5 may be coupled to a shaft 4 and a gear assembly 54 (FIGS. 5, 6) configured to articulate the fins 5. The fins may actuate about an axis substantially perpendicular to a longitudinal axis of the hull. According to one aspect, shaft 4 may havea length less than the radius of the hull where the shaft is disposed through the hull. Load bearing elements, such as bushings or the like, may be embedded or otherwise coupled to the hull 3, through which the shaft 4 may be disposed. As force is exerted on the shaft 4, the bushings may dissipate such forces to the hull 3, reducing the strain on the fins 5.

[0043] The fins 5 may be coupled to the shaft 4 by a threaded connector 52, such as a bolt, screw, dowel, or the like. As described herein, the rotation of the gear assembly 54 may cause the shaft 4 to rotate, thus driving the articulation of the fin 5. According to one aspect, the fins 5 may be quickly and easily removeable and interchangeable by removing the connector 52, swapping in anew fin 5 and recoupling the connector 52. Such a feature enables rapid repair and redeployment of the AUV should a fin de damaged during transport or operation. While the tailcone assembly 100 is described including a gear assembly 54, one skilled in the art will recognize that other configurations of a power transmission stack may be implemented, including belt and pulley or the like.

[0044] According to one aspect, the fins 5 may be articulated by a drive module 2 (e.g., servo assembly), as shown in FIG. 4 and FIG. 5. The drive module 2 may include one or more drivers, such as servo motors 20, adapted to drive the gear assemblies 54 coupled to the fins 5. Each servo motor 20 may be coupled to at least one drive gear 22 adapted to engage the fin gear assembly 54. The servo motors 20 may be controlled and driven by a controller (not shown), like that described in connection with FIG. 10, to provide active roll compensation during the operation of the AUV. Through sensor feedback, the servo motors 20 may monitor and maintain the rotational orientation of the AUV by adjusting the position of the fins 5 to actively compensate for unwanted roll caused by the torque generated by the movement and thrust of the AUV. While the drive module 2 is described having one or more servos, one skilled in the art will recognize that the drivers are not limited only to servos and may include other driver configurations.including but not limited to, actuators, feedback controlled actuators, angular actuators, or the like.

[0045] According to one aspect, the drive module 2 may be easily installed and removed. In assembly , the drive module 2 may be coupled to the hull 3 at one or more mounting points 26 (FIG. 6) and secured by one or more fasteners 24, such as a threaded connector, bolt, screw, dowel, or the like. As the drive module 2 is coupled to the hull 3, the drive gears 22 may engage the fin gear assemblies 54 coupling the servo motors 20 to the fin shafts 4 and the fins 5 themselves. The motor assembly (e.g., the flange 12, the motor 10 and the motor shaft 14) may be threadedly coupled to the hull 3 with the motor shaft 14 disposed through a central channel defined in the drive module 2 through which the motor shaft 14 passes. To disassemble, the flange 12 may be unthreaded from the hull 3, the motor shaft 14 may be withdrawn from the central channel of the drive module 2, and the drive module fasteners 24 may be removed. The drive gears 22 may be decoupled from the fin gear assemblies 54 and the drive module 2 may be removed, repaired, replaced, or the like. The interchangeable configuration of the drive module 2 also creates open space within the tailcone assembly 100 facilitating assembly and servicing of the tailcone and interacting with one or more ports 60 when adding new or servicing existing payloads.

[0046] As seen in the front and rear views of the tailcone assembly 100 in FIG. 6, the hull 3 may internally define or include one or more ports, generally labeled 60. The ports 60 may be adapted to provide sealed throughways from the interior to the exterior of the hull 3. without allowing ingress of water or other contaminants. The ports 60 may provide channels or other passages, for example, for pressure relief or backfill (60a), disposition of a pressure sensor (60b) or a tow line port (60c) adapted to receive tow lines, cables or other attachments to a particular payload. According to one aspect, ports 60 may facilitateor include ports for, without limitation, one or more internal environmental augmentation ports port, atmospheric gas exchange ports, power ports, communication ports coupled to a payload, or multipurpose ports. According to one aspect, the ports may be shrouded with a quick release cowling (FIG. 9) component to improve hy drody namic performance, while preserving accessibility for operators.

[0047] An on / off switch 19 may be coupled to a port providing power into the vehicle through this port in order to power it externally. Looped conductors inside the switch 19 may provide power to the on-board systems through the port. According to one aspect, the same port may be used as a charging port to supply power and charge the system.

[0048] According to one aspect, a hull cap 7 may be coupled to the aft section of the hull 3, about a lip seal assembly 6. An acetyl bearing, or the like, may be disposed in the hull cap 7 and about the motor shaft 14 which may allow for near-frictionless rotation of the motor shaft 14 and propeller 18. In one aspect, a shroud 8 may be disposed about the propeller 18 to provide protection of the propeller 18 as well as passive roll compensation. According to one aspect, the shroud 8 may include one or more stators, fixed fins, flanges or the like, adapted to provide passive roll compensation to the AUV.

[0049] According to one aspect, the shroud 8 may be removeable and interchangeable with other shrouds of different sizes, shapes and configurations. The hot-swappable ability of the shroud 8 allows the tailcone and AUV added flexibility in their intended applications. As detailed herein, passive roll compensation mechanisms may be designed for a specific cruising velocity. If the AUV is operated outside of the specific cruising velocity (or a minimal range thereabout), the compensation mechanisms may not function properly. Accordingly, the interchangeability of the shroud 8 allows the tailcone assembly100 to be used across multiple applications and deployments where cruising speeds maydiffer by exchanging a shroud 8 with one suitably designed for the new application without compromising the integrity of the sealed and isolated system.

[0050] FIGS. 7-8 depict an AUV 700 featuring a tailcone 701 assembly in accordance with several aspects of the present disclosure. Tailcone 701 may be the same or substantially similar to the tailcone assembly 100 of FIGS. 1-6. FIG. 7 depicts a side view of an AUV 700 including the tailcone assembly 701 coupled to an aft section of the AUV 700. FIG. 8 depicts a perspective view of the AUV 700 and tail cone assembly 701 of FIG. 7. The AUV 700 may include an elongated body 702 with a rounded nose 710 providing a profile that is hydrodynamic and facilitates movement through the water. The body 702 of the AUV may include one or more payloads, sensors, processors, drivers, or other devices adapted to drive the AUV for its intended purpose. One such payload may include a controller for actuating a motor, like that described above, to drive the propeller 718 of the tailcone assembly 701. The propeller 718 may be protected by the shroud 708. The shroud 708, as detailed herein, may feature one or more passive roll compensators, such as one or more stators, adapted to passively counter-torque the AUV in relation to the torque forces generated by the motor and propeller. The stators may straighten the flow of water to increase efficiency as well as generate a counteracting torque relative to the torque bome from the propeller as the vehicle moves through the water. One or more fins 705 may be coupled to the tailcone assembly 701 through the hull 703 to actively compensate for the roll, as described above.

[0051] Turning now to FIG. 9, an alternative embodiment of a tailcone assembly 200 is shown. The tailcone assembly 200 is substantially similar to the tailcone assembly 100 of FIGS. 1-6, where like reference numbers refer to like components. The tailcone assembly 200 may include a drive module 2, hull 3, fins 5 and propeller 18, like those previously described. According to one aspect, the tail cone 200 may include an outboardmotor 11 for driving the propeller 18. The tail cone assembly 200 may further include a removeable cowling 16 disposed over the aft portion of the assembly 200 covering the ports 60 and a portion of the motor 7. According to one aspect, the cow ling may be coupled to the hull in a quick-release fashion, including for example, through a magnetic coupling or the like, allow ing easy removal of the cow ling 16 and easy access to the aft ports 60. According to another aspect, a mast 13 may be coupled to the hull 3 through a port, such as a multipurpose port 15. The mast 13 may include a threaded portion 17 for coupling the mast 13 to the hull 3 through the port 15. According to one aspect, the mast 13 may include additional components, including but not limited to, one or more lights, antennas, global positioning system (GPS) components, acoustic devices, sensors, or the like. While the multipurpose port 15 shown in FIG. 9 is configured to receive the mast 13, one skilled in the art will recognize that the port 15 may be configured as any of the other ports described here.

[0052] Turning now to FIG. 10, exemplary timeseries data is shown for an exemplary deployment of a vehicle with a tailcone assembly as detailed herein, such as tailcone assembly 100 (FIGS. 1-6) and tailcone assembly 701 (FIGS. 7-8). Notably, in FIG. 10a, exemplary data depicts desired heading, heading and an upper rudder over time. FIG. 10b depicts pitch, desired pitch, roll, standby elevator, and port elevator over time. FIG. 10c depicts depth, desired depth, thrust and battery. According to one aspect, reflected in the data of the graphs of FIG. 10. the vehicle using such a tailcone assembly is able to reach a desired depth (FIG. 10c) and hold the desired depth using elevators. The exemplary data also shows the vehicle also reaches the desired heading and is stable (FIG. 10a). Finally, the vehicle has substantially no roll (FIG. 10b). The overshoot on the desired depth target(FIG. 10c) may be due to the physical dynamics of the vehicle, the quality of the controller, and the placement of the pressure sensor in the aft section of the vehicle (i.e.,the nose cone reaches depth first, and when it stabilizes, the aft section sinks to level with the nose, before floating back up). This overshoot, however, does not diminish the practical effectiveness of the tailcone assembly described herein.

[0053] Referring to FIG. 11, in some embodiments, a controller or computing device 1000 may be configured to drive or otherwise control the tailcone assemblies described herein. The controller 1100 may include or communicate with a processor 1102, volatile memory' 1104 (e.g., RAM), non-volatile memory' 1106 (e.g., a hard disk drive, a solid-state drive such as a flash drive, a hybrid magnetic and solid-state drive, etc.), graphical user interface (GUI) 1108 (e.g., a touchscreen, a display, and so forth) and input / output (I / O) device 1120 (e.g., a mouse, a keyboard, etc.). Non-volatile memory 806 stores computer instructions 1112, an operating system 1116 and data 1118 such that, for example, the computer instructions 1112 are executed by the processor 1102 out of volatile memory 1104. Program code may be applied to data entered using an input device of GUI 1108 or received from I / O device 1120.

[0054] The illustrative aspects of the tailcone design described herein meet the basic requirements of thrust, maneuvering depth, and maneuvering across the longitudinal / latitudinal plane. Aspects of the present disclosure also provide for a tailcone with an arrangement of control surfaces which support active roll compensation. Further aspects of the present disclosure include a hot-swappable shroud and stator system which provides passive roll compensation in addition to the active compensation. A user may therefore design and implement a shroud for a unique or particular mission and nominal cruising speed, while achieving hydrodynamically’ optimal performance.

[0055] According to other aspects of the disclosure, the illustrative tailcone assembly may provide, in a hydrodynamically optimal location, a number or ports, including without limitation, a charging port, a battery cell balancing port, an internal environmentalaugmentation port, and an atmospheric gas exchange port. The tailcone assembly may further provide a payload port for towing acoustic and / or scientific sensors. The payload port may also provide pow er and communication to such payloads. The tailcone assembly may also provide structural features adapted to provide strain relief for tow ed payloads.

[0056] According to one aspect, the removable drive module (i.e., the servo assembly) may provide significant solutions to known design issues. For example, the removeable drive module may improve the modularity of the system. The drive module, according to one aspect, may decouple the actuators or drivers from the control surfaces during disassembly, where load-bearing elements, such as bushing and the like, are embedded in the hull of tailcone. This allows the fin shaft to be much shorter than in conventional tailcones. The shorter fin shaft induces less of a moment on the hull and the sealing surfaces, which may be rigidly secured with the bushings, which in turn protect the sealing surfaces from impact. Additionally, wear and tear can be reduced by maintaining a uniform loading. For example, the fin shaft 4 (FIG. 4) may only be about !4” longer than the thickness of the hull wall.

[0057] Further, the decoupling of the actuators during disassembly opens the space within the tailcone making it easier to assemble the tailcone, service the tailcone, and interact with the payload ports when adding new payloads. This also reduces costs for the manufacturer.

[0058] The modular nature of the drive module may also improve cable management, by letting the module be disconnected from the rest of the wires in the aft section, such that the drive module is not harnessed with other systems in the cavity of the hull.

[0059] According to another aspect, the fin design of the tailcone assembly provides significant technical advantages. The fins may be hot-swappable, such that that if a fin breaks or is otherwise damaged, the fin can be replaced without opening the vehicle orcompromising the sealing surface. Further, while the fins are by default contained within the diameter of the vehicle, the platform area can be increased in order to have more control authority' (i.e., increase the rudder size, or the elevator sizes).

[0060] According to one aspect, the arrangement of the actuators and the fins may enable the fins to be contained within the hull diameter, maintaining portability and ease of stowage. This allows an operator to keep and work on the vehicle on any flat surface, in field operations or anywhere else.

[0061] Although reference is made herein to particular materials, it is appreciated that other materials having similar functional and / or structural properties may be substituted where appropriate, and that a person having ordinary skill in the art would understand how to select such materials and incorporate them into embodiments of the concepts, techniques, and structures set forth herein without deviating from the scope of those teachings.

[0062] Various embodiments of the concepts, systems, devices, structures and techniques sought to be protected are described herein with reference to the related drawings. Alternative embodiments can be devised without departing from the scope of the concepts, systems, devices, structures and techniques described herein. It is noted that various connections and positional relationships (e.g., over, below, adjacent, etc.) are set forth between elements in the following description and in the drawings. These connections and / or positional relationships, unless specified otherwise, can be direct or indirect, and the described concepts, systems, devices, structures and techniques are not intended to be limiting in this respect. Accordingly, a coupling of entities can refer to either a direct or an indirect coupling, and a positional relationship between entities can be a direct or indirect positional relationship.

[0063] As an example of an indirect positional relationship, references in the present description to forming layer "A" over layer "B" include situations in which one or more intermediate layers (e g., layer "C") is between layer "A" and layer "B" as long as the relevant characteristics and functionalities of layer "A" and layer "B" are not substantially changed by the intermediate layer(s).The following definitions and abbreviations are to be used for the interpretation of the claims and the specification. As used herein, the terms "comprises," "comprising, "includes," "including," "has," "having," "contains" or "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, a mixture, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or apparatus.

[0064] Additionally, the term "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms "one or more" and "one or more" are understood to include any integer number greater than or equal to one, i.e., one, two, three, four, etc. The terms "a plurality" are understood to include any integer number greater than or equal to two, i.e., two, three, four, five, etc. The term "connection" can include an indirect "connection" and a direct "connection."

[0065] References in the specification to "one embodiment, "an embodiment," "an example embodiment," etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment can include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, orcharacteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0066] For purposes of the description hereinafter, the terms "upper," "lower," "right," "left," "vertical," "horizontal." "top," "bottom," and derivatives thereof shall relate to the described structures and methods, as oriented in the drawing figures. The terms "overlying," "atop," "on top, "positioned on" or "positioned atop" mean that a first element, such as a first structure, is present on a second element, such as a second structure, where intervening elements such as an interface structure can be present between the first element and the second element. The term "direct contact" means that a first element, such as a first structure, and a second element, such as a second structure, are connected without any intermediary elements.

[0067] Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0068] The terms “approximately” and “about” may be used to mean within ±20% of a target value in some embodiments, within ±10% of a target value in some embodiments, within ±5% of a target value in some embodiments, and yet within ±2% of a target value in some embodiments. The terms “approximately” and “about” may include the target value. The term “substantially equal” may be used to refer to values that are wi thin ±20% of one another in some embodiments, within ±10% of one another in some embodiments.within ±5% of one another in some embodiments, and yet within ±2% of one another in some embodiments.

[0069] The term ‘"substantially” may be used to refer to values that are within ±20% of a comparative measure in some embodiments, within ±10% in some embodiments, within ±5% in some embodiments, and yet within ±2% in some embodiments. For example, a first direction that is “substantially” perpendicular to a second direction may refer to a first direction that is within ±20% of making a 90° angle with the second direction in some embodiments, within ±10% of making a 90° angle with the second direction in some embodiments, within ±5% of making a 90° angle with the second direction in some embodiments, and yet within ±2% of making a 90° angle with the second direction in some embodiments.

[0070] It is to be understood that the disclosed subject matter is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the disclosed subject matter. Therefore, the claims should be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the disclosed subject matter.

[0071] Although the disclosed subject matter has been described and illustrated in the foregoing exemplary embodiments, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of implementationof the disclosed subject matter may be made without departing from the spirit and scope of the disclosed subject matter.

Claims

CLAIMS1. An assembly comprising: a hull having an exterior surface and defining a cavity; a motor having a shaft disposed at least partially within the hull; a drive module disposed in the cavity, the drive module including one or more drivers; a plurality of fins disposed about the exterior surface of the hull, each fin coupled to one of the one or more drivers; and a propeller assembly coupled to the shaft, the propeller assembly including a shroud.

2. The assembly of claim 1 wherein the one or more drivers includes one or more servo motors.

3. The assembly of claim 1 wherein each of the one or more drivers includes a gear assembly.

4. The assembly of claim 3 wherein each gear assembly is coupled to a fin shaft, the fin shaft extending from the cavity through the exterior surface and coupled to one of the plurality of fins.

5. The assembly of claim 1 wherein the fins are interchangeable.

6. The assembly of claim 1 wherein the propeller assembly is interchangeable.

7. The assembly of claim 1 wherein the shroud is interchangeable.

8. The assembly of claim 1 wherein the shroud includes a passive roll compensator.

9. The assembly of claim 1 wherein the drive module is interchangeable.

10. The assembly of claim 1 wherein the drive module further includes a controller adapted to actuate the plurality of fins.

11. The assembly of claim 10 wherein the drive module is adapted to provide active roll compensation by actuating one or more of the fins.

12. The assembly of claim 1 wherein the hull defines at least one port.

13. The assembly of claim 12 wherein the at least one port is one of payload port, a power port, a communication port, an internal environmental augmentation port, a multipurpose port, a battery-cell balancing port and a charging port.

14. The assembly of claim 1 wherein the motor is waterproof and external to the hull.

15. The assembly of claim 1 wherein each of the plurality of fins are within a diameter profile of the hull.

16. The assembly of claim 1 wherein the hull defines at least one strain relief mount.

17. The assembly of claim 1 wherein the fins actuate about an axis substantially perpendicular to a longitudinal axis of the hull.

18. The assembly of claim 1 wherein each of the plurality of fins is coupled to a shaft having a length less than a radius of the hull where the shaft is disposed through the hull.

19. A tailcone assembly comprising: a hull defining a cavity; a motor having a shaft disposed at least partially within the hull; a drive module removeable disposed in the cavity, the drive module including one or more servo motors, each of the one or more servo motors providing control of three degrees of freedom; a plurality of fins disposed about an exterior surface of the hull, each fin removably coupled to one of the one or more servo motors;a propeller assembly coupled to the shaft, the propeller assembly including a shroud; and a controller coupled to the motor and the one or more servo motors, the controller configured to drive the servo motors to direct the plurality of fins to provide active roll compensation.

20. An autonomous underwater vehicle comprising: a nose; a body coupled to the nose; a controller; and a tailcone assembly in communication with the controller, the tailcone assembly comprising: a hull having an exterior surface and defining a canty; a motor having a shaft disposed at least partially within the hull; a drive module disposed in the cavity, the drive module including one or more drivers; a plurality of fins disposed about the exterior of the hull, each fin coupled to one of the one or more drivers; and a propeller assembly coupled to the shaft, the propeller assembly including a shroud.

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