Autonomous submersible side thrust recovery method and apparatus

Abstract

This invention belongs to the field of autonomous underwater vehicle (AUV) recovery technology, specifically disclosing a side-thrust recovery method and apparatus for AUVs. The recovery method includes the following steps: Step 1, the mother ship releases a recovery boat with a cable to the water surface and controls the recovery boat to move towards the AUV; Step 2, when the distance between the recovery boat and the AUV reaches a set distance, the position of the recovery boat is adjusted, and then the mechanical claw at the front of the recovery boat grabs the AUV from the side; Step 3, the mother ship retrieves the cable, and the cable drives the recovery boat and the AUV to move to the mother ship; This invention provides a side-thrust recovery method and apparatus for AUVs that can flexibly, efficiently, and safely recover AUVs.

Description

Technical Field

[0001] This invention belongs to the field of autonomous submersible recovery technology, specifically relating to a side-thrust recovery method and device for an autonomous submersible. Background Technology

[0002] An Autonomous Underwater Vehicle (AUV) is an unmanned system capable of independently performing underwater missions. It possesses capabilities such as autonomous navigation, data acquisition and processing, and decision-making, without requiring human remote control. AUVs have autonomous navigation capabilities, accurately measuring their position, attitude, and motion status through built-in navigation systems such as inertial navigation systems, Global Positioning System (GPS), sonar, and depth sensors. AUVs typically have underwater communication capabilities, enabling data transmission and communication with control stations on land or the surface. With continuous technological advancements, AUVs have achieved a high degree of autonomy and intelligence, enabling them to perform complex underwater tasks and play a vital role in fields such as marine science, marine exploration, and marine engineering.

[0003] Due to their superior performance in the marine environment, AUVs are now widely used in military and civilian fields. AUV deployment and recovery are among the most extensively researched areas. This is because the complex and variable marine environment makes conventional methods such as sling retrieval, traditional robotic arm retrieval, and towing retrieval difficult to use for docking and grabbing autonomous underwater vehicles, resulting in poor recovery outcomes. Currently, the most reliable method for autonomous underwater vehicles is manual intervention recovery. However, manual intervention recovery requires highly skilled divers and often carries significant risks. Therefore, a more flexible, adaptable, safe, and reliable AUV recovery method is needed. Summary of the Invention

[0004] The purpose of this invention is to provide a side-thrust recovery method and apparatus for autonomous underwater vehicles (AUVs) that can be used flexibly, efficiently and safely.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for recovering an autonomous submersible using a side thruster includes the following steps:

[0007] Step 1: The mother ship releases the recovery boat with the cable to the surface of the water and controls the recovery boat to move towards the autonomous submersible.

[0008] Step 2: When the distance between the recovery boat and the autonomous underwater vehicle reaches the set distance, adjust the position and attitude of the recovery boat, and then the mechanical claw at the front of the recovery boat grabs the autonomous underwater vehicle from the side.

[0009] Step 3: The mother ship retrieves the cable, which then moves the recovery boat and autonomous underwater vehicle to the mother ship.

[0010] Furthermore, in step 2, the method for adjusting the attitude of the recovery vessel is as follows: when the distance between the recovery vessel and the autonomous underwater vehicle reaches 5-10m, the lateral thrusters, forward thrusters and steering rudders are used to adjust the relative position and direction of the recovery vessel and the autonomous underwater vehicle, so that the bow of the recovery vessel is orthogonal to the axis of the autonomous underwater vehicle, and the recovery vessel is controlled to move towards the autonomous underwater vehicle along the axis perpendicular to the autonomous underwater vehicle.

[0011] Furthermore, in step 2, the method for the mechanical claw to grasp the autonomous underwater vehicle is as follows: control the two mechanical claws to open, and simultaneously control the mechanical claws to rotate so that the lower half of the mechanical claws is submerged underwater and the upper half is exposed above the water surface; then control the first mechanical claw to close and grasp the autonomous underwater vehicle, then control the first mechanical claw to adjust the attitude of the autonomous underwater vehicle; finally control the second mechanical claw to grasp the autonomous underwater vehicle.

[0012] Furthermore, in step 2, the method for controlling the second mechanical claw to grasp the autonomous underwater vehicle is as follows: first, adjust the distance between the second mechanical claw and the first mechanical claw, and then control the second mechanical claw to close and grasp the autonomous underwater vehicle.

[0013] Furthermore, in step 2, the distance between the second mechanical claw is adjusted so that the two mechanical claws are symmetrical about the center position of the autonomous submersible.

[0014] Furthermore, in step 2, after the robotic gripper grasps the autonomous underwater vehicle (AUV), if the sensor detects that the robotic gripper is not holding the AUV tightly, the robotic gripper is controlled to open, and then the process of step 2 is repeated until the AUV is successfully grasped.

[0015] An autonomous underwater vehicle (AUV) side-thrust recovery device capable of implementing any of the above methods includes a mother ship connected to a recovery pod via a cable. The recovery pod is equipped with a lateral thruster on its side, a forward thruster, and a steering rudder. A pair of mechanical claws with a large grasping margin are located at the front of the recovery pod, and infrared sensors are installed on the mechanical claws. The mechanical claws are connected to a distance adjustment mechanism for adjusting the distance between the two mechanical claws.

[0016] Furthermore, the distance adjustment mechanism includes a pair of telescopic crossbars arranged in a cross configuration, which are connected by a rotating connector; the front end of each telescopic crossbar is rotatably connected to a mechanical claw, and the two mechanical claws are slidably connected to the recovery boat, with the sliding direction of the mechanical claws perpendicular to the bow direction of the unmanned boat; the rear ends of the two telescopic crossbars are connected to a rotating assembly.

[0017] Furthermore, the rotating assembly includes two rear sliders, each of which is rotatably connected to the rear end of the telescopic crossbar. The two rear sliders are slidably connected to a rear slide rod. The sliding direction of the rear sliders is consistent with that of the mechanical gripper. The rear slide rod is slidably connected to the unmanned surface vessel. The sliding direction of the rear slide rod is perpendicular to that of the rear sliders. The rear slide rod is connected to a rear linear actuator.

[0018] Furthermore, the rotating connector is slidably connected to the recovery boat, and the sliding direction of the rotating connector is consistent with that of the rear slide bar; the two mechanical claws are symmetrical about the sliding direction of the rotating connector.

[0019] Furthermore, each telescopic crossbar has a support frame rotatably connected to its front end, and two support frames are slidably connected to a forearm fixing rod, which is fixedly connected to the unmanned surface vessel (USV). A front linear actuator is rotatably connected to each support frame, and a connecting plate is rotatably connected to the front end of each front linear actuator. Each connecting plate is rotatably connected to the support frame, and the front end of each connecting plate is connected to a mechanical gripper. The rear and front linear actuators can use electric actuators, lead screws, hydraulic actuators, or other similar structures.

[0020] Furthermore, a satellite communication module and a hull stabilizer are installed in the middle of the recovery vessel. The hull stabilizer includes a liftable counterweight. An underwater sonar is connected to the bottom of the hull stabilizer, and a rotating turntable is connected to the bottom of the underwater sonar. A cable fixing seat is connected to the bottom of the rotating turntable. The cable is connected to the bottom of the recovery vessel through the cable fixing seat.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. This invention utilizes a miniaturized, self-stabilizing unmanned recovery vessel. Through a combination of a lateral thruster, a forward thruster, and a steering rudder, the unmanned vessel's mechanical claw at the front end can grab and recover autonomous underwater vehicles (AUVs) from the side. The movement of the unmanned vessel and the mechanical claw is more flexible, making it easier to adjust the angle and position of the AUV being grabbed. This allows for efficient recovery of AUVs near the water surface. This highly flexible unmanned system enables rapid recovery of AUVs in complex sea conditions.

[0023] 2. The unmanned surface vessel (USV) is equipped with a rotatable and retractable mechanical claw at its front end. This claw provides a large grasping margin, significantly improving the success rate of the self-stabilizing recovery vessel in capturing autonomous underwater vehicles (AUVs). The USV only needs to move the mechanical claw, without moving the AUV itself. This reduces power requirements and simplifies the structure. Guided by the principle of "small investment, big return," an innovative, compact, and intelligent recovery device has been designed to recover AUVs larger than itself. This compact recovery vessel is inexpensive, highly intelligent, and possesses remote positioning and communication capabilities. Furthermore, after successfully capturing the AUV, the recovery vessel coordinates with the mother ship using its onboard cable to return to port, effectively avoiding the inconvenience caused by carrying the target AUV and improving recovery reliability.

[0024] 3. Adjusting the position of the recovery boat makes it easier for the mechanical claws to grab the autonomous underwater vehicle (AUV). The two mechanical claws grabbing the AUV in sequence can adjust the lateral position of the mechanical claws relative to the AUV, making the two mechanical claws symmetrical about the middle position of the AUV, so that the mechanical claws can stably hold the AUV and prevent the AUV from falling.

[0025] 4. The mechanical claws can move synchronously laterally via telescopic crossbars. Under the constraints of the crank and rotating connector, the two ends of the telescopic crossbars are always symmetrical about the middle of the unmanned surface vessel (USV), thus ensuring that the two mechanical claws are always symmetrical about the middle of the USV. This prevents the USV from deviating to one side after being grabbed, ensuring the stable recovery of the USV.

[0026] 5. The forearm fixing rod restricts the mechanical claw to lateral movement relative to the recovery vessel, preventing longitudinal movement. This simplifies the claw's trajectory adjustment and improves gripping stability. The hull stabilizer maintains the unmanned surface vessel's stability. In rough seas, the extended stabilizer provides high stability, reducing hull sway and acting as a self-stabilizer. In favorable sea conditions, the stabilizer shortens to reduce underwater resistance during recovery vessel movement and conserve energy. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the recovery boat moving towards the autonomous submersible in Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of the attitude adjustment of the recovery boat in Embodiment 1 of the present invention;

[0029] Figure 3 This is a schematic diagram of the recovery boat capturing the autonomous submersible in Embodiment 1 of the present invention;

[0030] Figure 4 This is a schematic diagram of adjusting the distance of the mechanical claws on the recovery boat according to Embodiment 1 of the present invention;

[0031] Figure 5 This is a schematic diagram of the mechanical claw gripping the autonomous underwater vehicle according to Embodiment 1 of the present invention;

[0032] Figure 6 This is a schematic diagram of the mother ship recovery cable in Embodiment 1 of the present invention;

[0033] Figure 7 This is a schematic diagram of the autonomous submersible being recovered to the mother ship in Embodiment 1 of the present invention;

[0034] Figure 8 This is a side view of the recovery vessel according to Embodiment 2 of the present invention;

[0035] Figure 9 This is a front view of the recovery vessel according to Embodiment 2 of the present invention;

[0036] Figure 10 This is an isometric view of the recovery boat according to Embodiment 2 of the present invention;

[0037] Figure 11 for Figure 10 A magnified view of a portion of the image;

[0038] Figure 12 for Figure 10 A magnified view of a portion of the image, B.

[0039] In the diagram: 1. Mother ship; 2. Cable; 3. Recovery boat; 4. Autonomous submersible; 5. Stern anchor; 6. Hull stabilizer; 7. Underwater sonar; 8. Rotary turntable; 9. Lateral thruster; 10. Cable anchor; 11. Forward thruster; 12. Cabin; 13. Satellite communication module; 14. Guide rail limiting seat; 15. Mechanical claw; 16. Telescopic crossbar; 17. Pin; 18. Telescopic limit block; 19. Crank bar; 20. Top frame fixing rod; 21. Front slider; 22. Forearm fixing rod; 23. Support frame; 24. Push rod pivot; 25. Forearm electric push rod; 26. Connecting plate; 27. Forearm pivot; 28. Rear slider; 29. ​​Rear slide bar; 30. Moving guide rail; 31. Rear electric push rod; 32. Motor fixing rod. Detailed Implementation

[0040] Example 1

[0041] A method for recovering an autonomous submersible using a four-side thruster, such as Figure 1-7 As shown, it includes the following steps:

[0042] Step 1: Recovery vessel 3 moves towards autonomous submersible 4; during recovery of autonomous submersible 4, autonomous submersible 4 surfaces, as if... Figure 1 As shown, the mother ship 1 releases the recovery boat 3 with the cable 2 to the water surface. The recovery boat 3 receives the position information from the autonomous underwater vehicle 4, obtains the current water surface path from the recovery boat 3 to the AUV through the path planning algorithm, and uses low-level control technology to track the planned path and control the recovery boat 3 to move towards the autonomous underwater vehicle 4.

[0043] Step 2, the recovery boat 3 adjusts its attitude; such as Figure 2 As shown, when the distance between the recovery boat 3 and the autonomous underwater vehicle 4 reaches 5m, the lateral thruster 9, the forward thruster 11 and the steering rudder are used to adjust the position and attitude of the recovery boat 3 so that the bow of the recovery boat 3 is orthogonal to the axis of the autonomous underwater vehicle 4; then the forward thruster 11 pushes the recovery boat 3 forward toward the autonomous underwater vehicle 4 in a direction perpendicular to the axis of the autonomous underwater vehicle 4, and the lateral thruster 9 pushes the recovery boat 3 to move laterally in a direction parallel to the axis of the autonomous underwater vehicle 4 so that the bow is aligned with the middle position of the autonomous underwater vehicle 4.

[0044] Step 3, recovery boat 3 retrieves autonomous submersible 4; as Figure 3-5 As shown, the two mechanical claws 15 at the front of the recovery vessel 3 open, and simultaneously control the rotation of the mechanical claws 15 so that the lower half of the mechanical claws 15 is submerged underwater and the upper half is exposed above the water surface; then control the first mechanical claw 15 to close and grab the autonomous underwater vehicle 4, and then control the first mechanical claw 15 to adjust the attitude of the autonomous underwater vehicle 4; grab the autonomous underwater vehicle 4 from the side; then adjust the lateral distance between the second mechanical claw 15 and the first mechanical claw 15 so that the two mechanical claws 15 are symmetrical about the middle position of the autonomous underwater vehicle 4, and then control the second mechanical claw 15 to close and grab the autonomous underwater vehicle 4. After the two mechanical claws 15 grab the autonomous underwater vehicle 4, if the sensors in the mechanical claws 15 sense that the mechanical claws 15 have not gripped the autonomous underwater vehicle 4 tightly, then control the mechanical claws 15 to open, and then repeat the process of steps 2-3 until the autonomous underwater vehicle 4 is successfully grabbed.

[0045] Step 4: Retrieve the autonomous submersible 4 back to the mothership 1; Figure 6-7 As shown, the mother ship 1 pulls the recovery boat 3 to the deck via the recovery cable 2, and then the mechanical claw 15 of the recovery boat 3 releases, releasing the autonomous submersible 4 onto the deck.

[0046] Step 5: When multiple autonomous submersibles 4 are being recovered or multiple recovery boats 3 are operating, repeat steps 1-4 to recover all autonomous submersibles 4 to the mother ship 1.

[0047] Example 2

[0048] An autonomous submersible 4 side-thrust recovery device implementing the method in Embodiment 1 includes a mother ship 1, which is connected to a recovery boat 3 via a cable 2. In this embodiment, the recovery boat 3 is a catamaran. Figure 8-12 As shown, the recovery boat 3 is equipped with a lateral thruster 9 on its side, and a forward thruster 11 and a steering rudder are also provided on the recovery boat 3; the lateral thruster 9 is used to propel the recovery boat 3 to move laterally, the forward thruster 11 is used to propel the recovery boat 3 to move longitudinally, and the steering rudder is used to adjust the forward direction of the recovery boat 3.

[0049] like Figure 8-9 As shown, the recovery vessel 3 includes a stern mounting base 5 to increase the mechanical strength of the hull; a satellite communication module 13 and a hull stabilizer 6 are installed in the middle of the recovery vessel 3. The hull stabilizer 6 includes a counterweight and a lifting assembly connected to the counterweight; an underwater sonar 7 is connected to the bottom of the hull stabilizer 6, a rotating turntable 8 is connected to the bottom of the underwater sonar 7, and a cable fixing seat 10 is connected to the bottom of the rotating turntable 8; the cable 2 is connected to the bottom of the recovery vessel 3 through the cable fixing seat 10, and the recovery vessel 3 is bolted to a guide rail limiting seat 14. The unmanned surface vessel's cabin 12 is equipped with two forward thrusters and four lateral thrusters 9. The six thrusters work together to increase the maneuverability of the recovery vessel 3. The length of the hull stabilizer 6 in the middle of the recovery vessel 3 is variable, and it can be extended or shortened in the direction perpendicular to the sea surface.

[0050] The front of the recovery vessel 3 is equipped with a pair of existing mechanical claws 15 that can open and close autonomously. The two parts of the mechanical claws 15 are arranged vertically. Each mechanical claw 15 is equipped with an infrared sensor to detect whether the mechanical claw 15 is gripping the autonomous underwater vehicle 4. The mechanical claws 15 are connected to a distance adjustment mechanism to adjust the distance between the two mechanical claws 15. The clamping plate of the recovery vessel 3 is set horizontally, and the bow of the recovery vessel 3 is longitudinal.

[0051] like Figure 10-12 As shown, the distance adjustment mechanism includes a pair of horizontally arranged telescopic cross rods 16, which are rotatably connected by a vertical pin 17. Each pin 17 has a telescopic limiting block 18 at its top, and a crank 19 is slidably connected to the limiting block 18. The crank 19 is horizontally and longitudinally arranged, and is fixed to the middle position of the recovery boat 3 via a top frame fixing rod 20. The two mechanical claws 15 and the cabin 12 are symmetrical about the crank 19.

[0052] Each telescopic crossbar 16 has a front slider 21 rotatably connected to its front end. The telescopic crossbar 16 rotates horizontally around the front slider 21. Two front sliders 21 are slidably connected to a forearm fixing rod 22, which is horizontally arranged and fixed to the front end of the unmanned surface vessel. Each front slider 21 is fixedly connected to a support frame 23, which is longitudinally arranged. Each support frame 23 is connected to a push rod shaft 24 at its rear. The push rod shafts 24 are all horizontally arranged, and a forearm electric push rod 25 is rotatably connected to each push rod shaft 24. The rear end of the forearm electric push rod 25 is connected to the push rod shaft 24, and the front end of each forearm electric push rod 25 is rotatably connected to a connecting plate 26. The rotation axis of the forearm electric push rod 25 and the connecting plate 26 is parallel to the push rod shaft 24. Each connecting plate 26 is rotatably connected to the support frame 23 through a forearm shaft 27. The forearm shaft 27 is arranged in front of the push rod shaft 24 and is parallel to the push rod shaft 24. The forearm shaft 27 is connected to the support frame 23. The forearm electric push rod 25, the connecting plate 26 and the support frame 23 on the same support frame 23 form a triangular structure. The front end of each connecting plate 26 is fixedly connected to the mechanical claw 15.

[0053] like Figure 10 , Figure 12 As shown, the rear ends of the two telescopic crossbars 16 are connected to rotating components, which include two rear sliders 28. Each rear slider 28 is rotatably connected to the rear end of the telescopic crossbar 16, and the rotation axes of the telescopic crossbar 16 and the rear sliders 28 are vertically arranged. The two rear sliders 28 are slidably connected to a rear sliding rod 29, which is parallel to the forearm fixing rod 22. The sliding direction of the rear sliders 28 is the same as that of the mechanical claw 15. Both ends of the rear sliding rod 29 are slidably connected to moving guide rails 30. Each moving guide rail 30 is arranged horizontally and longitudinally, and each moving guide rail 30 is fixed to the unmanned surface vessel (USV) through a guide rail limiting seat 14. The rear sliding rod 29 slides longitudinally along the moving guide rail 30. A rear electric push rod 31 is connected to the rear sliding rod 29. The front end of the rear electric push rod 31 is connected to the rear sliding rod 29, and the rear end of the rear electric push rod 31 is connected to a motor fixing rod 32, which is fixed to the recovery vessel 3. The two rear sliders 28 are symmetrical about the crank 19.

[0054] When the mechanical gripper 15 is rotated, the forearm electric push rod 25 extends and retracts, causing the connecting plate 26 to rotate around the forearm pivot 27, and the connecting plate 26 causes the mechanical gripper 15 to rotate.

[0055] When grabbing the autonomous underwater vehicle 4, the rear electric push rod 31 extends and retracts, causing the rear slide rod 29 to move longitudinally on the recovery boat 3. The rear slide rod 29 causes the rear slider 28 to move longitudinally together with it. Since the rear slider 28 and the rear end of the telescopic cross rod 16 rotate together around the pin 17, the rear slider 28 moves laterally along the rear slide rod 29 while moving longitudinally. Since the front end of the telescopic cross rod 16 can only move laterally along the front arm fixing rod 22 with the front slider 21 and cannot move longitudinally, the telescopic cross rod 16 drives the telescopic limit block 18 to move longitudinally along the crank rod 19 through the pin 17. While the rear slider 28 moves laterally, it causes the telescopic cross rod 16 to rotate. The telescopic cross rod 16 causes the front slider 21, the support frame 23 and the mechanical claw 15 to move laterally together, adjusting the distance between the two mechanical claws 15. At the same time, under the restriction of the crank rod 19, the pin 17 moves along the crank rod 19, so that the mechanical claw 15 is always symmetrical about the crank rod 19.

Claims

1. A method for recovering an autonomous submersible using a side thruster, characterized in that, Includes the following steps, Step 1: The mother ship releases the recovery boat with the cable to the surface of the water and controls the recovery boat to move towards the autonomous submersible. Step 2: Adjust the position of the recovery boat, and then the mechanical claw at the front of the recovery boat will grab the autonomous underwater vehicle from the side. Step 3: The mother ship retrieves the cable, which then moves the recovery boat and autonomous underwater vehicle to the mother ship. In step 2, the method for adjusting the attitude of the recovery boat is as follows: when the distance between the recovery boat and the autonomous underwater vehicle reaches 5-10m, the recovery boat is adjusted using the lateral thrusters, forward thrusters and steering rudders so that the bow of the recovery boat is orthogonal to the axis of the autonomous underwater vehicle, and the recovery boat is controlled to move forward in a direction perpendicular to the axis of the autonomous underwater vehicle. The method for the mechanical gripper to grasp the autonomous underwater vehicle (AUV) is as follows: control the two mechanical grippers to open, and simultaneously control the mechanical grippers to rotate so that the lower half of the mechanical grippers is submerged underwater and the upper half is exposed above the water surface; then control the first mechanical gripper to close and grasp the AUV, and then control the first mechanical gripper to adjust the attitude of the AUV; then adjust the lateral distance between the second mechanical gripper and the first mechanical gripper, and then control the second mechanical gripper to close and grasp the AUV.

2. The autonomous submersible side-thrust recovery method as described in claim 1, characterized in that, In step 2, after the two robotic grippers grasp the autonomous underwater vehicle (AUV), if the sensors detect that the grippers are not holding the AUV tightly, the grippers are opened, and the process of step 2 is repeated until the AUV is successfully grasped.

3. A side-thrust recovery device for an autonomous submersible, capable of implementing the method described in claim 1 or 2, characterized in that, The system includes a mother ship, to which a recovery vessel is connected by a cable. The recovery vessel is equipped with a lateral thruster on its side, a forward thruster, and a steering rudder. The front of the recovery vessel is equipped with a pair of mechanical claws, each equipped with an infrared sensor. The mechanical claws are connected to a distance adjustment mechanism. The distance adjustment mechanism includes a pair of telescopic crossbars arranged in a cross configuration, which are connected by a rotating connector. The front end of each telescopic crossbar is rotatably connected to a mechanical claw, and the two mechanical claws are slidably connected to the recovery boat. The sliding direction of the mechanical claws is perpendicular to the bow direction of the unmanned boat. A rotating assembly is connected to the rear end of the two telescopic crossbars. The rotating assembly includes two rear sliders, each of which is rotatably connected to the rear end of a telescopic crossbar. The two rear sliders are slidably connected to a rear sliding rod. The sliding direction of the rear sliders is consistent with that of the mechanical gripper. The rear sliding rod is slidably connected to the unmanned surface vessel. The sliding direction of the rear sliding rod is perpendicular to that of the rear sliders. The rear sliding rod is connected to a rear linear actuator.

4. The autonomous submersible side-thrust recovery device as described in claim 3, characterized in that, The rotating connector is slidably connected to the recovery boat, and the sliding direction of the rotating connector is consistent with that of the rear slide bar; the two mechanical claws are symmetrical about the sliding direction of the rotating connector.

5. The autonomous submersible side-thrust recovery device as described in claim 4, characterized in that, Each of the telescopic crossbars is rotatably connected to a support frame at its front end, and two support frames are slidably connected to a forearm fixing rod, which is fixedly connected to the unmanned surface vessel. Each support frame is rotatably connected to a front linear actuator, and the front end of each front linear actuator is rotatably connected to a connecting plate. Each connecting plate is rotatably connected to the support frame, and the front end of each connecting plate is connected to a mechanical claw.

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