A highly maneuverable, low-drag underwater vehicle

Abstract

This invention discloses a highly maneuverable, low-drag underwater vehicle (AUV), comprising a head assembly, a mid-section assembly, and a tail assembly. The head assembly mainly includes a multi-purpose lateral thruster; the mid-section assembly includes a pitch adjustment device and a buoyancy adjustment device; and the tail assembly includes a cross-shaped tail rudder and a tail propeller. By adjusting the variable-structure shell, the lateral thruster can spray water forward to achieve backward movement of the AUV, and the attitude can be changed by rotating the lateral thruster around the AUV's axis. This invention enables highly efficient backward movement of the AUV and adjustment of its attitude in any spatial configuration through the head-mounted lateral thruster. Installed inside the variable-structure shell, the structure is compact and does not affect the AUV's hydrodynamic shape, greatly increasing the AUV's speed and maneuverability.

Description

Technical Field

[0001] This invention belongs to the field of novel underwater vehicles, and in particular relates to a highly maneuverable, low-resistance underwater vehicle. Background Technology

[0002] The exploration and development of the ocean has become a common theme of human development. Autonomous Underwater Vehicles (AUVs), as widely used marine exploration equipment, play an indispensable and crucial role in relevant marine activities in both civilian and military fields.

[0003] In the current domestic and international marine exploration field, AUV technology has reached a high level of maturity. However, its attitude and position adjustment in space mainly falls into two categories: the first uses the thrust of a single propeller as forward propulsion, combined with several rotatable rudders to adjust heading and pitch; the second uses the thrust of several propellers as forward propulsion or steering force to achieve high-precision navigation parameter control of the AUV. Generally, considering factors such as energy consumption, hydrodynamics, and range, the number of driving forces for both types of AUVs is less than 6, making AUVs still underactuated. Therefore, improving the accuracy of the AUV's trajectory or its maneuverability in underactuated conditions remains a significant research area. The addition of lateral propellers and bow thrust propellers can improve the AUV's steering maneuverability and dead reckoning capabilities, respectively, but the disruption of its hydrodynamic shape will significantly increase water resistance, thereby reducing its range.

[0004] Lateral propellers can only improve the steering ability of an AUV in a single plane. Patent CN202220379164.X proposes a 360-degree rotating composite propulsion mechanism for AUVs. While this improves the steering ability, it disrupts the hydrodynamic shape, severely limiting its range. How to improve the steering maneuverability and dead reckoning capability of an AUV without compromising its hydrodynamic shape is not addressed in existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an autonomous underwater vehicle (AUV) with low drag, the ability to move backward, and a highly maneuverable nose, suitable for complex underwater exploration missions.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A highly maneuverable, low-resistance underwater vehicle includes a head assembly, a middle assembly, and a tail assembly connected sequentially from front to back. The head assembly is characterized in that it includes an end cap, a front fairing, a variable-structure shell, a head shell, a rear support, a gear shaft, a steering motor gear, an angle sensor gear, a lateral thruster, a steering motor, a cylindrical guide rail, and a front support.

[0008] The front support is connected to the tail of the front fairing, the top of the front fairing is provided with a water outlet, and the water outlet is provided with an end cap that is rotatably connected to the fairing. The rear support is connected to the front of the head shell.

[0009] The front and rear supports are fixedly connected by cylindrical guide rails. The lateral thruster is fixedly connected to the gear shaft, which is rotatably connected to the rear support and driven by the steering motor. The variable-structure shell is slidably connected to the rear support. The movement of the variable-structure shell can change the water spray direction of the underwater AUV. The gear shaft meshes with the steering motor gear and the angle sensor gear, respectively. The variable-structure shell can convert the water spray direction of the lateral thruster to the direction along the axis of the AUV hull, and achieve the AUV's backward movement through reaction force.

[0010] The mid-section assembly includes a pitch adjustment device and a buoyancy adjustment device. The pitch adjustment device adjusts the position of the AUV's center of gravity through a battery pack that can move along the AUV's axial direction, thereby changing the AUV's pitch angle. The buoyancy adjustment device changes the volume of the outer bladder through a hydraulic system to change the AUV's buoyancy, thereby controlling the AUV's ascent and descent.

[0011] The tail assembly includes a cruciform tail rudder and a tail propeller, wherein the cruciform tail rudder can change the AUV's sailing attitude; the tail propeller is located at the very end of the AUV's tail and provides propulsion for the AUV.

[0012] Furthermore, the head assembly also includes a lead screw nut, a lead screw, a lead screw motor, a guide rail flange, and a bellows; three cylindrical guide rails are provided between the front and rear supports, and each is threadedly connected to both ends of the cylindrical guide rails with a nut; three guide rail flanges are fixedly connected to the end face of the variable-structure housing, and the guide rail flanges are slidably connected to the cylindrical guide rails, allowing the variable-structure housing to slide back and forth along the cylindrical guide rails; the lead screw motor is fixedly connected to the rear support, one end of the lead screw is connected to the output shaft of the lead screw motor, and the other end of the lead screw is rotatably connected to the front support; the lead screw nut is fixedly connected to the end face of the variable-structure housing, and the lead screw motor drives the opening and closing of the variable-structure housing through the cooperation of the lead screw and the lead screw nut; the two ends of the bellows are respectively connected to the water outlet on the flow guide cover and the flow guide pipe on the variable-structure housing, for spraying water forward; the flow guide cover is rotatably connected to the end cover via a hinge, and automatically opens due to the thrust of the water spraying out.

[0013] Furthermore, the head assembly also includes a motor drive box, an angle sensor, and an angle sensor bracket. The angle sensor is fixedly connected to the angle sensor bracket. The motor drive box, steering motor, and angle sensor bracket are all fixedly connected to the rear bracket. The shaft of the angle sensor passes through the rear bracket and is fixedly connected to the angle sensor gear. The output shaft of the steering motor passes through the rear bracket and is connected to the steering motor gear. The gear end face of the gear shaft has four threaded holes for fixing the lateral thruster on the gear shaft. The gear shaft is rotatably connected to the rear bracket. The gear shaft is a hollow shaft. The drive power line of the lateral thruster passes through the hollow gear shaft. The lateral thruster can rotate around the axis of the AUV. The gear end face of the gear shaft has a slot that communicates with the hollow part in the middle of the gear shaft. The motor drive box contains a motor driver for the lateral thruster, which is used to drive the lateral thruster to rotate.

[0014] Furthermore, the gear shaft and the rear support are rotatably connected by a deep groove ball bearing. The inner ring of the deep groove ball bearing is fixed by the shaft shoulder of the gear shaft and the bearing lock nut, while the outer ring is fixed by the rear support and the retaining ring of the hole, restricting the lateral thruster to rotate only around the axis of the AUV.

[0015] Furthermore, by opening and closing the head-mounted variable-structure shell, the direction of water spray from the side thrusters is changed, thereby achieving the two functions of controlling the AUV's backward movement and head turning.

[0016] Furthermore, the variable-structure shell is a cylindrical shape with a fully open top and a partially open tail. The top of the variable-structure shell has an annular slope to reduce resistance. A guide pipe for changing the direction of water flow is fixed inside the variable-structure shell. Several holes are evenly distributed on the bottom end face of the variable-structure shell for installing guide rail flanges and lead screw nuts. A rectangular hole is provided in the middle of the bottom end face of the variable-structure shell.

[0017] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0018] 1. The underwater vehicle of this invention can spray water forward to propel the AUV backward, increasing the diversity of AUV movement. Compared with the traditional method of reversing the tail propeller of the AUV to achieve the backward effect, it has higher propulsion efficiency and greatly increases the endurance of the AUV.

[0019] 2. The underwater vehicle of this invention adopts a highly maneuverable nose steering. Compared with traditional AUVs, the AUV of this invention has a zero turning radius, can achieve rapid maneuvering attitude and position adjustment, and the system control is simple and reliable through direct space drive.

[0020] 3. The lateral thrusters at the head of the underwater vehicle of the present invention can be covered by a cylindrical variable-structure shell. When the AUV needs to make a large turn, the variable-structure shell can be opened to expose the lateral thrusters and adjust them to a suitable angle to achieve AUV attitude adjustment. Therefore, it will not change the hydrodynamic shape and will not have an adverse effect on the normal navigation of the AUV.

[0021] 4. The underwater vehicle of the present invention can generate a torque to change attitude directly through the lateral thruster when stationary or at low speed, which makes up for the shortcomings of rudder adjustment at low speed and greatly increases the maneuverability of the AUV.

[0022] 5. The underwater vehicle of the present invention achieves two purposes with a single lateral thruster. It can both adjust the attitude of the AUV and move the AUV backward by adjusting the modified shell. While increasing the mobility of the AUV, it does not add too many propulsion devices.

[0023] 6. During normal horizontal cruising of the AUV, the underwater vehicle of the present invention can still adjust its attitude by means of the cross-shaped tail rudder at the tail. This method can avoid the large amount of power consumption and the increase in drag caused by the change in hydrodynamic shape caused by direct adjustment through the head side thrusters.

[0024] 7. The underwater vehicle of this invention uses an angle sensor to measure the rotation angle of the lateral thruster in real time, determine the thrust direction of the lateral thruster, and ensure the accuracy of the AUV's motion attitude.

[0025] 8. The underwater vehicle of this invention has multiple AUV attitude adjustment methods, including a head-mounted lateral thruster, a mid-mounted pitch adjustment device and a buoyancy adjustment device, and a tail-mounted cross rudder adjustment, realizing the coupling of three attitude adjustments. In actual navigation, different attitude adjustment methods can be used comprehensively and selectively according to actual needs, which not only increases the maneuverability of the AUV, but also ensures stability, and increases the AUV's motion accuracy and endurance.

[0026] 9. The underwater vehicle of this invention can quickly adjust the AUV to a vertical attitude through the head-mounted side thruster. By using the propeller at the tail and cooperating with the buoyancy adjustment system to change the buoyancy, the AUV can achieve rapid vertical ascent and descent. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the AUV of the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of the head assembly of the present invention in the open state of the variable-structure outer shell.

[0029] Figure 3This is a schematic diagram of the lateral thruster of the head assembly of the present invention.

[0030] Figure 4 This is a full sectional view of the head assembly of the present invention.

[0031] Figure 5 This is an enlarged structural schematic diagram of the head assembly of the present invention in its retracted state.

[0032] Reference numerals: 1-Head assembly; 2-Middle assembly; 3-Tail assembly; 4-End cover; 5-Front fairing; 6-Variable housing; 7-Head housing; 8-Pitch adjustment device; 9-Buoyancy adjustment device; 10-Cruze tail rudder; 11-Tail propeller; 12-Rear support; 13-Gear shaft; 14-Steering motor gear; 15-Angle sensor gear; 16-Side thruster; 17-Lead screw nut; 18-Lead screw; 19-Lead screw motor; 20-Motor drive box; 21-Retaining ring for bore; 22-Bearing lock nut; 23-Steering motor; 24-Angle sensor; 25-Angle sensor bracket; 26-Cylindrical guide rail; 27-Guide rail flange; 28-Bellwall; 29-Diffuser; 30-Deep groove ball bearing; 31-Front support; 32-Hinge Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0034] This embodiment provides a highly maneuverable, low-resistance underwater vehicle, the overall appearance of which is as follows: Figure 1 As shown, it includes a head assembly 1, a mid-section assembly 2, and a tail assembly 3. The head assembly mainly includes a multi-purpose lateral thruster. The mid-section assembly 2 includes a pitch adjustment device 8 and a buoyancy adjustment device 9. Moving the battery pack can adjust the position of the battery pack inside the cabin, thereby changing the position of the AUV's center of gravity and realizing the adjustment of the AUV's pitch attitude. The tail assembly 3 includes a cross tail rudder 10 and a tail propeller 11.

[0035] See Figures 2-5 The front bracket 31 is a circular plate with multiple holes, which is fixedly connected to the tail of the front fairing 5 by four circumferential protrusions evenly distributed at the end of the circumference. The front bracket 31 and the rear bracket 12 are fixed by a cylindrical guide rail 26. The two ends of the cylindrical guide rail 26 are threaded. Two sets of nuts and washers are used to clamp the front bracket 31 (rear bracket 12) in the middle, thereby fixing the front bracket 31 (rear bracket 12) to the cylindrical guide rail 26.

[0036] See Figures 2-5The variable-structure outer shell 6 is a cylindrical shape with one end fully open and the other end partially open. An internal guide pipe 29 for changing the direction of water flow is fixedly connected. Four cylindrical holes are evenly distributed on the end face of the variable-structure outer shell 6, used to install three guide flanges 27 and a lead screw nut 17. A rectangular hole is located in the middle of the end face. During the closing process of the variable-structure outer shell 6, a cylindrical lateral thruster 16 can pass through the end face of the variable-structure outer shell 6. Three guide flanges 27 are fixed to the end face of the variable-structure outer shell 6 by screws. The guide flanges 27 are connected to the cylindrical guide... The guide rail 26 is slidably fitted. Due to the clearance fit between the variable housing 6 and the guide shield, the variable housing 6 can slide back and forth along the cylindrical guide rail 26 under the drive of the lead screw motor 19. The lead screw motor 19 is fixedly connected to the rear support 12 by screws, and the other end of the lead screw 18 is rotatably connected to the front support 31. The lead screw nut 17 is fixedly connected to the end face of the variable housing 6. The lead screw motor 19 pushes the variable housing 6 to open and close through the screw screw 18 and the lead screw nut 17. The function of switching the side thruster 16 to spray water is to change the attitude or move backward. The guide shield is a combination of cylindrical and hemispherical shapes. There is a water outlet channel on the hemispherical surface. The two ends of the bellows 28 are respectively connected to the water outlet on the front guide shield 5 and the guide pipe 29 on the variable housing 6 to guide the water flow forward. The front guide shield 5 is rotatably connected to the end cap 4 by the hinge 32 to automatically open when the water flow is sprayed.

[0037] See Figure 2-5The rear support 12 is a circular plate with holes for various parts. It is fixed to the head housing 7 by bolts through four circumferential protrusions evenly distributed at the end of the circumference. The circumferential plane of the rear support 12 has multiple holes in the axial direction for mounting components such as gear shaft 13, steering motor 23, angle sensor 24, lead screw 18 and cylindrical guide rail 26. The angle sensor 24 is fixedly connected to the angle sensor bracket 25, and the angle sensor bracket 25 is fixedly connected to the rear support 12. The shaft of angle sensor 24 passes through rear bracket 12 and is fixedly connected to angle sensor gear 15. Angle sensor 24 and angle sensor gear 15 are fixedly connected by set screws. Angle sensor gear 15 meshes with gear shaft 13, thereby feeding back the rotation angle of gear shaft 13 to angle sensor 24 in real time, obtaining accurate angle information of lateral thruster 16. Steering motor 23 is fixedly connected to rear bracket 12. The output shaft of steering motor 23 passes through rear bracket 12 and is fixedly connected to steering motor gear 14 by set screws. Steering motor gear 14 meshes with gear shaft 13, thus enabling steering motor 23 to rotate. The rotation of 3 is transmitted to the gear shaft 13; the gear shaft 13 and the rear support 12 are rotatably connected by a deep groove ball bearing 30. The inner ring of the deep groove ball bearing 30 is fixed by the shaft shoulder of the gear shaft 13 and the bearing lock nut 22, and the outer ring is fixed by the rear support 12 and the retaining ring 21. Therefore, the side thruster 16 of the head can only rotate around the axis of the AUV and cannot move in the axial direction. Because the deep groove ball bearing 30 can withstand a certain bending moment, the thrust of the side thruster 16 can be well supported. The motor drive box 20 contains the motor driver of the side thruster 16, which is used to drive the side thruster to rotate.

[0038] See Figure 1 During normal cruise, the AUV can perform normal functions such as diving, constant depth navigation, surfacing and hovering by using the cross tail rudder 10, tail propeller 11, buoyancy adjustment device 9 and pitch adjustment device 8. This control method is technically mature and the movement process is stable. When the AUV needs to change position and attitude quickly, it can make adjustments quickly through the lateral thrusters 16 at the head, which has high maneuverability. Therefore, it has a combination of stability and maneuverability.

[0039] Specifically, the main processes and principles of the high-maneuverability, low-resistance underwater vehicle in this embodiment during operation are as follows:

[0040] When the AUV needs to reverse: the side thrusters 16 of the head are activated, drawing water into the side thrusters 16 through the sieve-like holes at the bottom of the head housing 7 and spraying the water upwards. The water flow passes through the guide pipe 29 in the variable housing 6, changing its direction from upwards relative to the AUV to forwards. The water flow passes sequentially through the connected bellows 28 and the outlet of the front guide shroud 5. Due to the thrust of the water flow, the rotating end cap 4 on the front guide shroud 5 is pushed, thus rotating upwards and opening. Therefore, the water flow can be smoothly sprayed forward relative to the AUV, and the AUV reverses. When the AUV moves forward normally, due to the thrust of the water flow on the end cap 4, the end cap 4 is pressed against the front guide shroud 5 and will not open on its own. When the AUV sprays water forward through the channel, the pressure of the water flow can push the end cap 4 open.

[0041] When the AUV needs to change its attitude: the lead screw motor 19 rotates, and the lead screw 18 and lead screw nut 17 engage in a screw-like engagement. Since the lead screw nut 17 is fixed to the variable-structure housing 6, it pushes the variable-structure housing 6 to slide forward relative to the AUV until the side thrusters 16 at the head are fully exposed. At this time, the outlet of the side thrusters 16 is vertically upward. According to the target attitude requirements, the main controller issues a command to drive the steering motor 23 to rotate. The steering motor 23 transmits the rotation angle to the side thrusters 16 through the meshing steering motor gear 14 and gear shaft 13. Therefore, the side thrusters 16 can rotate a full circumference around the AUV axis. Since the angle sensor gear 15 and gear shaft 13 mesh with each other, the rotation angle of the side thrusters 16 can be transmitted to the angle sensor in real time. The sensor 24 determines the current orientation of the nozzles of the side thrusters 16, allowing for more precise and real-time control of the AUV's head rotation direction. When the nozzles of the side thrusters 16 on the AUV's head rotate to the desired position, the side thrusters 16 begin to operate. Because the side thrusters 16 are located at the head of the AUV, the thrust generated by the side thrusters 16 will produce a torque on the AUV, causing it to rotate around the center, thus changing the AUV's attitude. At this time, the tail propeller 11 is opened for propulsion, and the AUV moves in the direction the head is pointing. After completing the entire attitude and position adjustment process, the side thrusters 16 rotate to the initial position, and the lead screw motor pushes the variable-structure housing 16 backward until it closes, restoring the AUV's initial shape.

[0042] When the AUV is sailing normally: it can achieve normal functions such as diving, constant depth navigation, surfacing and hovering through the cross tail rudder 10, tail propeller 11, buoyancy adjustment device 9 and pitch adjustment device 8.

[0043] Finally, it should be noted that the above examples are only used to illustrate the calculation process of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing examples, those skilled in the art should understand that modifications can still be made to the calculation process described in the foregoing examples, or equivalent substitutions can be made to some of the parameters. Such modifications or substitutions do not cause the essence of the corresponding calculation method to deviate from the spirit and scope of the calculation method of the present invention.

Claims

1. A highly maneuverable, low-drag underwater vehicle, comprising a head assembly (1), a mid-section assembly (2), and a tail assembly (3) connected sequentially from front to back, characterized in that, The head assembly includes an end cap (4), a front fairing (5), a variable housing (6), a head housing (7), a rear bracket (12), a gear shaft (13), a steering motor gear (14), an angle sensor gear (15), a lateral thruster (16), a steering motor (23), a cylindrical guide rail (26), and a front bracket (31). The front support (31) is connected to the tail of the front guide shield (5), the top of the front guide shield (5) is provided with a water outlet, and the water outlet is provided with an end cap (4) that is rotatably connected to the front guide shield (5). The rear support (12) is connected to the front of the head shell (7). The front support (31) and the rear support (12) are fixedly connected by a cylindrical guide rail (26). The lateral thruster (16) is fixedly connected to the gear shaft (13). The gear shaft (13) is rotatably connected to the rear support (12) and driven by the steering motor (23). The variable-structure shell (6) is slidably connected to the rear support (12). The movement of the variable-structure shell (6) can change the water spray direction of the underwater AUV. The gear shaft (13) meshes with the steering motor gear (14) and the angle sensor gear (15) respectively. The variable-structure shell can convert the water spray direction of the lateral thruster (16) into the direction along the axis of the AUV hull, and realize the backward movement of the AUV through the reaction force. The central assembly (2) includes a pitch adjustment device (8) and a buoyancy adjustment device (9). The pitch adjustment device (8) adjusts the position of the center of gravity of the AUV by means of a battery pack that can move along the axial direction of the AUV, thereby changing the pitch angle of the AUV. The buoyancy adjustment device (9) changes the volume of the outer bladder through a hydraulic system to change the buoyancy of the AUV, thereby controlling the AUV's ascent and descent. The tail assembly (3) includes a cross tail rudder (10) and a tail propeller (11), wherein the cross tail rudder (10) can change the navigation attitude of the AUV; the tail propeller (11) is located at the very end of the tail of the AUV and provides propulsion for the AUV. The head assembly also includes a lead screw nut (17), a lead screw (18), a lead screw motor (19), a guide rail flange (27), and a bellows (28); three cylindrical guide rails (26) are provided between the front bracket (31) and the rear bracket (12), and each is connected to the two ends of the cylindrical guide rails by a nut; three guide rail flanges (27) are fixedly connected to the end face of the variable housing (6), and the guide rail flanges (27) are slidably connected to the cylindrical guide rails (26), and the variable housing (6) can slide back and forth along the cylindrical guide rails; the lead screw motor (19) is fixedly connected to the rear bracket (12), and the lead screw (18) of the lead screw (18) One end is connected to the output shaft of the lead screw motor (19), and the other end of the lead screw (18) is rotatably connected to the front bracket (31). The lead screw nut (17) is fixedly connected to the end face of the variable structure shell (6). The lead screw motor (19) rotates and engages with the lead screw nut (17) through the lead screw (18) to push the opening and closing of the variable structure shell (6). The two ends of the bellows (28) are respectively connected to the water outlet on the front guide shroud and the guide pipe (29) on the variable structure shell (6) to spray water forward. The front guide shroud (5) is rotatably connected to the end cover (4) through the hinge (32) and automatically opens by the thrust when the water is sprayed out. By opening and closing the head-mounted variable shell (6), the direction of water sprayed by the side thruster (16) is changed, thereby realizing the two functions of controlling the AUV's backward movement and head turning respectively. The variable structure shell (6) is a cylindrical shape with a fully open top and a partially open tail. The top of the variable structure shell (6) is provided with an annular slope to reduce resistance. The interior of the variable structure shell (6) is fixed with a guide pipe (29) for changing the direction of water flow. Several holes are evenly distributed on the bottom end face of the variable structure shell (6) for installing guide rail flanges and screw nuts. A rectangular hole is provided in the middle of the bottom end face of the variable structure shell (6).

2. The highly maneuverable, low-resistance underwater vehicle according to claim 1, characterized in that, The head assembly also includes a motor drive box (20), an angle sensor (24), and an angle sensor bracket (25). The angle sensor (24) is fixedly connected to the angle sensor bracket (25). The motor drive box (20), the steering motor (23), and the angle sensor bracket (25) are all fixedly connected to the rear bracket (12). The shaft of the angle sensor (24) passes through the rear bracket (12) and is fixedly connected to the angle sensor gear (15). The output shaft of the steering motor (23) passes through the rear bracket (12) and is connected to the steering motor gear (14). The gear shaft (1) 3) The gear end face has four threaded holes for fixing the side thruster (16) on the gear shaft (13); the gear shaft (13) is rotatably connected to the rear bracket (12). The gear shaft (13) is a hollow shaft. The drive power line of the side thruster (16) passes through the hollow gear shaft. The side thruster can rotate around the axis of the AUV. The gear end face of the gear shaft (13) is provided with a slot that communicates with the hollow part in the middle of the gear shaft. The motor drive box (20) contains the motor driver of the side thruster (16) for driving the side thruster to rotate.

3. A highly maneuverable, low-resistance underwater vehicle according to claim 2, characterized in that, The gear shaft (13) and the rear support (12) are rotatably connected by a deep groove ball bearing (30). The inner ring of the deep groove ball bearing (30) is fixed by the shoulder of the gear shaft (13) and the bearing lock nut (22), and the outer ring is fixed by the rear support (12) and the hole retaining ring (21), which restricts the lateral thruster (16) to rotate only around the axis of the AUV.

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