An autonomous capture and recovery docking system and method for an underwater robot

Abstract

An underwater robot capture type autonomous recovery docking system and method, comprising: a flat body, a rack, a guide mechanism, a capture mechanism, a single drive mechanism and a force bearing structure arranged in cooperation; the rack is fixed inside the flat body to form a whole support frame, the guide mechanism and the capture mechanism are hinged to the front end of the rack and are arranged symmetrically left and right, respectively, to undertake the position correction and locking function of the recovery ball; the single drive mechanism is fixed to the tail of the rack and the output end is simultaneously connected with the guide mechanism and the capture mechanism for transmission, providing power for the guide mechanism and the capture mechanism; the force bearing structure is welded and fixed to the center position of the front end of the rack for bearing the recovery ball and all tensile load in the recovery process, so as to protect the capture mechanism from being damaged; a five-stage autonomous recovery docking operation method is designed, and a three-stage abnormal processing flow is set, effectively improving the recovery fault tolerance and stability of the underwater robot in complex sea conditions.

Description

Technical Field

[0001] This invention relates to the field of autonomous underwater robot recovery technology, specifically to an underwater robot capture-type autonomous recovery docking system and method. Background Technology

[0002] Underwater robots are playing an increasingly important role in fields such as marine oil exploration, underwater rescue, seabed salvage, and marine scientific research. However, underwater robots have limited energy carrying capacity, and must be recovered after performing long-term missions to replenish energy and transmit data. Currently, the recovery of underwater robots mainly relies on manual operation or underwater docking. Manual recovery is inefficient and risky, while underwater docking is costly, time-consuming, and a static docking method, unsuitable for dynamic docking and recovery scenarios in complex sea conditions.

[0003] While existing capture-and-recovery systems can achieve dynamic docking, most adopt multi-drive docking methods, resulting in an overly complex overall structure. They rely excessively on external mother ships and complex guidance systems, and lack independent operating procedures for the docking system itself. This leads to an overly chaotic overall action sequence, poor locking reliability, and a significant drop in recovery success rate under high sea states, failing to meet the requirements for efficient autonomous recovery. Summary of the Invention

[0004] This invention provides an underwater robot capture-type autonomous recovery and docking system and method. The system and method are rationally designed, based on the collaborative design of a flat main body, guiding mechanism, capture mechanism, single drive mechanism, and load-bearing structure. It integrates the docking device structure with the autonomous recovery operation method, enabling synchronous operation of the guiding and capture functions. This allows for adaptation to the synchronous characteristics of the single drive mechanism, achieving a compact, low-resistance, and highly reliable autonomous docking and recovery. Furthermore, it provides a repeatable docking operation process and a three-level anomaly handling process, forming a two-level guidance mode (near and far range), adaptable to various operating platforms, eliminating the need for manual intervention, improving recovery efficiency, ensuring smooth docking, and providing better maneuverability and longer endurance. This invention solves the problems existing in the prior art.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: An underwater robot capture-type autonomous recovery and docking system, the recovery and docking system comprising: a flat main body, a frame, a guiding mechanism, a capture mechanism, a single drive mechanism, and a load-bearing structure arranged in a coordinated manner; The frame is fixed inside the flat main body to form an integral support frame. The guiding mechanism and the capture mechanism are hinged to the front end of the frame and arranged symmetrically on the left and right, respectively undertaking the functions of position correction and locking of the retrieved ball. The single drive mechanism is fixed to the rear end of the frame and its output end is simultaneously connected to the guiding mechanism and the capture mechanism, providing power to the guiding mechanism and the capture mechanism to achieve precise synchronization of their actions. The load-bearing structure is welded and fixed to the center position of the front end of the frame to bear the retrieved ball and all tensile loads during the retrieval process, so as to protect the capture mechanism from damage.

[0006] The flat body has a streamlined design and is formed by a flat upper shell and a flat lower shell. A watertight camera and an ultra-short transducer are installed on the front side respectively. The frame includes a bow arc-shaped frame, a bow section connecting rod, a front frame, and a stern frame. The bow arc-shaped frame is fixedly connected to the front frame with screws, and the front frame and the stern frame are fixedly connected with the bow section connecting rod. The bow arc-shaped frame is located at the foremost end of the frame and matches the streamlined profile of the front end of the flat main body to reduce fluid resistance. The front frame and the bow arc-shaped frame are fixedly connected with multiple countersunk screws to provide a stable mounting position for the guiding mechanism and the capture mechanism. The stern frame is used to install a single drive mechanism and is connected and fixed between the front frame and the stern frame by four parallel bow section connecting rods. The two ends of the connecting rods are inserted into the corresponding holes of the front and rear frames and locked with set screws.

[0007] The front of the flat upper shell and the flat lower shell are fitted and positioned with the upper and lower edges of the bow arc frame. The middle part is fixed to the front frame with screws, and the rear part is fixed to the tail frame with screws, forming a closed installation cavity to ensure the strength and rigidity of the overall structure and protect the internal mechanism from seawater corrosion. A dedicated mounting hole is provided at the front of the flat upper shell. The watertight camera is fixed in the hole through a sealing structure and is used to collect real-time image information of the recovered ball during the close-range recovery phase, providing data support for optical guidance. A transducer mounting base is integrally injection molded at the front of the flat lower shell. The ultra-short transducer is fixed in the base through a threaded connection and is used to conduct acoustic communication and positioning with the mother ship during the long-range recovery phase, enabling large-area target search.

[0008] The guiding mechanism includes guide rods and guide rod connecting rods arranged symmetrically on the left and right sides, and the guide rods and guide rod connecting rods are configured and used together; the rear end of the guide rod is rotatably connected to a hinge support fixed to the bow arc frame through a first hinge shaft, which is used to open underwater to form a funnel-shaped area to guide the recovery ball at the end of the recovery cable into the docking system; the front end of the guide rod is hinged to the front end of the guide rod connecting rod through a second hinge shaft; the lower part of the rear end of the guide rod connecting rod has a flat surface that forms surface contact with the front end of the push rod of the single drive mechanism.

[0009] The capture mechanism includes two capture claws, a capture claw locking hook, and a positioning detection sensor; the middle part of each capture claw is rotatably connected to a hinge support fixed to the bow arc frame via a first hinge shaft, which is used to rotate around the shaft to realize the opening and closing action; a cylindrical locking pin is provided at the rear end of the capture claw, which is used to cooperate with the capture claw locking hook to realize locking. The capture claw hook is rotatably connected to the bow arc frame via a third hinge shaft. One end is machined into a hook shape to hook the cylindrical locking pin at the rear end of the capture claw; the other end is machined into an inclined sliding surface to form a sliding contact with the corresponding inclined surface at the upper rear end of the guide rod connecting rod, thereby achieving mechanical linkage. The positioning detection sensor is fixedly installed in the front mounting slot of the bow arc frame via a slot and is located above the load-bearing structure. The positioning detection sensor is an infrared sensor, and its detection light path passes exactly through the preset positioning position of the recovery ball. When the recovery ball moves along the guide channel to contact the load-bearing structure, it blocks the infrared light path and generates a high-level trigger signal.

[0010] The single drive mechanism includes a drive unit, a transmission unit, a control unit, and a sealing sleeve; the drive unit is a DC geared motor, and a sealing sleeve is provided on its exterior. The sealing sleeve is fixedly connected to the tail frame by a flange and screws. The transmission unit includes a coupling, a lead screw, a nut, and a push rod. The output shaft of the DC geared motor is connected to the input end of the reducer. The output shaft of the DC geared motor is fixedly connected to one end of the lead screw via the coupling. The first nut is threaded into the other end of the lead screw. The second nut is fixedly connected to the rear end of the push rod. The front end of the push rod serves as the output end of the transmission assembly and forms surface contact with the lower rear end of the guide rod connecting rod. The control unit is fixedly installed on a preset mounting position on the tail frame via a slot. The control unit includes a power supply, a main control circuit board, a vision computer, and a video acquisition unit. It is used to receive position detection sensor signals and pressure sensor signals, and output forward and reverse rotation commands to the drive unit according to the control logic to control the operation of the DC geared motor.

[0011] When the drive unit drives the transmission unit to move the push rod forward, the push rod pushes the guide rod connecting rod to rotate around the second hinge axis, causing the guide rod to open outward to the working angle. The inclined surface at the rear end of the guide rod connecting rod disengages from the capture claw hook. Under its own gravity, the hook rotates around the third hinge axis, releasing the locking pin at the rear end of the capture claw. The capture claw then fully opens, and the docking system enters the capture-ready state. When the drive unit rotates in the opposite direction to move the push rod backward, the push rod pulls the guide rod connecting rod to rotate in the opposite direction, causing the guide rod to retract inward into the flat body. At the same time, the inclined surface at the rear end of the guide rod connecting rod presses the capture claw hook, causing the hook to rotate around the third hinge axis. Its hook head hooks the locking pin at the rear end of the capture claw and drives the capture claw to close inward, firmly locking the recovery ball between the load-bearing structure and the capture claw.

[0012] The load-bearing structure is fixedly connected to the lower center of the bow arc frame by welding. It is a metal block with an arc concave surface that matches the recovery ball, so as to form a surface contact with the recovery ball during towing and bear the pulling force during recovery and towing. The load-bearing structure is equipped with a pressure sensor to detect the recovery pressure of the recovery ball.

[0013] A method for autonomous capture and docking of an underwater robot, the method comprising the following steps: S1. Five minutes before the underwater robot reaches the recovery area, the docking system is powered on and started. The control unit checks the power supply voltage, motor current, sensor signals and communication links in sequence to ensure they are normal. After the self-test is passed, the control unit sends a forward drive command to the drive unit, which drives the push rod to move forward and opens the guide rod to the working angle. At the same time, the capture claw lock hook is unlocked, and the capture claw opens and enters the unlocked state. The docking system enters the capture state. S2, the underwater robot carrying the recovery ball sails toward the docking system at a preset speed. The underwater robot is acoustically located and guided from a distance by an ultra-short transducer. After gradually approaching the recovery ball, it is optically guided from a close distance by a watertight camera. When the recovery ball contacts the guide rod, it slides into the frame under the guidance of the guide rod. S3, as the underwater robot continues to move forward, the recovery ball moves along the guide rod and is pushed into the frame. The recovery ball slides down the guide rod until it contacts the load-bearing structure. The recovery ball blocks the infrared light path, and the positioning detection sensor is triggered, outputting a high-level capture signal. S4. After receiving the high-level capture signal, the control unit immediately sends a reverse drive command to the drive unit to control the DC geared motor to reverse and drive the push rod to move backward. While retracting the guide rod, the capture claw closes, locking the recovery ball between the load-bearing structure and the capture claw. When the capture claw is fully closed, the locking position switch is triggered, and a locking success signal is fed back to the control unit, and the motor stops and locks. S5: The recovery ball and recovery cable establish a reliable connection with the docking system, the recovery cable tightens, the recovery ball fits tightly with the load-bearing structure, the pressure sensor data is normal, and the docking is completed; when release is required, the DC motor rotates forward, the push rod moves forward, the capture claw opens, the guide rod opens, and the underwater robot can detach from the recovery docking system.

[0014] The recovery docking method also includes a three-level anomaly handling process, which addresses three common anomalies: capture failure, locking failure, and disengagement. Handling capture failure: If the positioning detection sensor does not detect a trigger signal within 10 seconds, it is determined that the capture has failed; the control unit keeps the mechanism in the open state, the underwater robot automatically retreats 20m, readjusts its course and depth, and then re-enters the guidance phase. It can be retried up to 3 times. If the capture fails 3 or more times, a distress signal is sent to the mother ship. Locking failure handling: If the positioning detection sensor has been triggered, but the locking positioning switch does not provide a feedback signal within 5 seconds, it is determined that the locking has failed; the control unit immediately drives the motor to rotate forward, opens the capture claw, and the underwater robot retreats 20m to retry, with a maximum of 3 retries. If the locking fails 3 or more times, a distress signal is sent to the mother ship. Disengagement handling: If the pressure sensor detects that the tension suddenly drops below 10% of the threshold, it is determined to be disengaged; the control unit immediately drives the motor to rotate forward, opens the capture claw to release the residual cable, and the underwater robot automatically retreats and re-enters the acoustic guidance stage.

[0015] This invention employs the aforementioned structure and method, integrating the docking system structure with an autonomous recovery operation method. A standardized five-stage operation process is designed alongside the docking system, adapting to the synchronous characteristics of a single-drive mechanism to avoid slippage of the recovery ball due to asynchronous movements. Long-distance acoustic guidance is achieved through an ultra-short transducer, and short-distance optical guidance through a watertight camera, forming a two-tiered guidance mode suitable for various operating platforms. A three-level complete anomaly handling mechanism is established, with corresponding solutions for three common operating conditions: capture failure, locking failure, and disengagement. No manual intervention is required, improving recovery efficiency and ensuring successful docking. The flat design of the docking system conforms to the shape of the underwater robot, reducing fluid resistance and offering advantages of high efficiency, practicality, stability, and reliability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the present invention.

[0017] Figure 2 for Figure 1 The front view.

[0018] Figure 3 for Figure 1 Side sectional view.

[0019] Figure 4 This is a schematic diagram of the locking state of the capturing claw according to the present invention.

[0020] Figure 5 This is a top view of the guiding mechanism and capturing mechanism of the present invention.

[0021] Figure 6 This is a top sectional view of the single drive mechanism of the present invention.

[0022] Figure 7 This is a side view of the captured state of the recovered ball according to the present invention.

[0023] Figure 8 for Figure 7 A magnified view of a portion of the image.

[0024] Figure 9 This is a schematic diagram of the process of the present invention.

[0025] Figure 10 This is a flowchart of the three-level exception handling process of the present invention.

[0026] In the diagram: 1. Flat main body; 2. Guiding mechanism; 3. Capture mechanism; 4. Single drive mechanism; 5. Load-bearing structure; 6. Frame; 7. Recovery ball; 8. First hinge shaft; 9. Second hinge shaft; 10. Third hinge shaft; 101. Watertight camera; 102. Ultra-short transducer; 103. Flat upper shell; 104. Flat lower shell; 201. Guide rod; 202. Guide rod connecting rod; 301. Capture claw; 302. Capture claw locking hook; 303. Position detection sensor ; 401, Drive unit; 402, Transmission unit; 403, Control unit; 404, Sealing sleeve; 601, Bow arc frame; 602, Bow section connecting rod; 603, Bow frame; 604, Tail frame; 4021, Coupling; 4022, Lead screw; 4023, First nut; 4024, Push rod; 4025, Second nut; 4031, Power supply; 4032, Main control circuit board; 4033, Vision computer; 4034, Video acquisition unit. Detailed Implementation

[0027] To clearly illustrate the technical features of this solution, the invention will be described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0028] like Figures 1-10 As shown in the figure, an underwater robot capture-type autonomous recovery and docking system includes: a flat main body, a frame, a guiding mechanism, a capture mechanism, a single drive mechanism, and a load-bearing structure arranged in a coordinated manner; The frame is fixed inside the flat main body to form an integral support frame. The guiding mechanism and the capture mechanism are hinged to the front end of the frame and arranged symmetrically on the left and right, respectively undertaking the functions of position correction and locking of the retrieved ball. The single drive mechanism is fixed to the rear end of the frame and its output end is simultaneously connected to the guiding mechanism and the capture mechanism, providing power to the guiding mechanism and the capture mechanism to achieve precise synchronization of their actions. The load-bearing structure is welded and fixed to the center position of the front end of the frame to bear the retrieved ball and all tensile loads during the retrieval process, so as to protect the capture mechanism from damage.

[0029] The flat body has a streamlined design and is formed by a flat upper shell and a flat lower shell. A watertight camera and an ultra-short transducer are installed on the front side respectively. The frame includes a bow arc-shaped frame, a bow section connecting rod, a front frame, and a stern frame. The bow arc-shaped frame is fixedly connected to the front frame with screws, and the front frame and the stern frame are fixedly connected with the bow section connecting rod. The bow arc-shaped frame is located at the foremost end of the frame and matches the streamlined profile of the front end of the flat main body to reduce fluid resistance. The front frame and the bow arc-shaped frame are fixedly connected with multiple countersunk screws to provide a stable mounting position for the guiding mechanism and the capture mechanism. The stern frame is used to install a single drive mechanism and is connected and fixed between the front frame and the stern frame by four parallel bow section connecting rods. The two ends of the connecting rods are inserted into the corresponding holes of the front and rear frames and locked with set screws.

[0030] The front of the flat upper shell and the flat lower shell are fitted and positioned with the upper and lower edges of the bow arc frame. The middle part is fixed to the front frame with screws, and the rear part is fixed to the tail frame with screws, forming a closed installation cavity to ensure the strength and rigidity of the overall structure and protect the internal mechanism from seawater corrosion. A dedicated mounting hole is provided at the front of the flat upper shell. The watertight camera is fixed in the hole through a sealing structure and is used to collect real-time image information of the recovered ball during the close-range recovery phase, providing data support for optical guidance. A transducer mounting base is integrally injection molded at the front of the flat lower shell. The ultra-short transducer is fixed in the base through a threaded connection and is used to conduct acoustic communication and positioning with the mother ship during the long-range recovery phase, enabling large-area target search.

[0031] The guiding mechanism includes guide rods and guide rod connecting rods arranged symmetrically on the left and right sides, and the guide rods and guide rod connecting rods are configured and used together; the rear end of the guide rod is rotatably connected to a hinge support fixed to the bow arc frame through a first hinge shaft, which is used to open underwater to form a funnel-shaped area to guide the recovery ball at the end of the recovery cable into the docking system; the front end of the guide rod is hinged to the front end of the guide rod connecting rod through a second hinge shaft; the lower part of the rear end of the guide rod connecting rod has a flat surface that forms surface contact with the front end of the push rod of the single drive mechanism.

[0032] The capture mechanism includes two capture claws, a capture claw locking hook, and a positioning detection sensor; the middle part of each capture claw is rotatably connected to a hinge support fixed to the bow arc frame via a first hinge shaft, which is used to rotate around the shaft to realize the opening and closing action; a cylindrical locking pin is provided at the rear end of the capture claw, which is used to cooperate with the capture claw locking hook to realize locking. The capture claw hook is rotatably connected to the bow arc frame via a third hinge shaft. One end is machined into a hook shape to hook the cylindrical locking pin at the rear end of the capture claw; the other end is machined into an inclined sliding surface to form a sliding contact with the corresponding inclined surface at the upper rear end of the guide rod connecting rod, thereby achieving mechanical linkage. The positioning detection sensor is fixedly installed in the front mounting slot of the bow arc frame via a slot and is located above the load-bearing structure. The positioning detection sensor is an infrared sensor, and its detection light path passes exactly through the preset positioning position of the recovery ball. When the recovery ball moves along the guide channel to contact the load-bearing structure, it blocks the infrared light path and generates a high-level trigger signal.

[0033] The single drive mechanism includes a drive unit, a transmission unit, a control unit, and a sealing sleeve; the drive unit is a DC geared motor, and a sealing sleeve is provided on its exterior. The sealing sleeve is fixedly connected to the tail frame by a flange and screws. The transmission unit includes a coupling, a lead screw, a nut, and a push rod. The output shaft of the DC geared motor is connected to the input end of the reducer. The output shaft of the DC geared motor is fixedly connected to one end of the lead screw via the coupling. The first nut is threaded into the other end of the lead screw. The second nut is fixedly connected to the rear end of the push rod. The front end of the push rod serves as the output end of the transmission assembly and forms surface contact with the lower rear end of the guide rod connecting rod. The control unit is fixedly installed on a preset mounting position on the tail frame via a slot. The control unit includes a power supply, a main control circuit board, a vision computer, and a video acquisition unit. It is used to receive position detection sensor signals and pressure sensor signals, and output forward and reverse rotation commands to the drive unit according to the control logic to control the operation of the DC geared motor.

[0034] When the drive unit drives the transmission unit to move the push rod forward, the push rod pushes the guide rod connecting rod to rotate around the second hinge axis, causing the guide rod to open outward to the working angle. The inclined surface at the rear end of the guide rod connecting rod disengages from the capture claw hook. Under its own gravity, the hook rotates around the third hinge axis, releasing the locking pin at the rear end of the capture claw. The capture claw then fully opens, and the docking system enters the capture-ready state. When the drive unit rotates in the opposite direction to move the push rod backward, the push rod pulls the guide rod connecting rod to rotate in the opposite direction, causing the guide rod to retract inward into the flat body. At the same time, the inclined surface at the rear end of the guide rod connecting rod presses the capture claw hook, causing the hook to rotate around the third hinge axis. Its hook head hooks the locking pin at the rear end of the capture claw and drives the capture claw to close inward, firmly locking the recovery ball between the load-bearing structure and the capture claw.

[0035] The load-bearing structure is fixedly connected to the lower center of the bow arc-shaped frame by welding. It is a metal block with an arc-shaped concave surface, which matches the arc-shaped concave surface of the recovery ball, so as to form surface contact with the recovery ball during towing and bear the pulling force during recovery towing. The load-bearing structure is equipped with a pressure sensor to detect the recovery pressure of the recovery ball.

[0036] The recycling docking method includes the following steps: S1. Five minutes before the underwater robot reaches the recovery area, the docking system is powered on and started. The control unit checks the power supply voltage, motor current, sensor signals and communication links in sequence to ensure they are normal. After the self-test is passed, the control unit sends a forward drive command to the drive unit, which drives the push rod to move forward and opens the guide rod to the working angle. At the same time, the capture claw lock hook is unlocked, and the capture claw opens and enters the unlocked state. The docking system enters the capture state. S2, the underwater robot carrying the recovery ball sails toward the docking system at a preset speed. The underwater robot is acoustically located and guided from a distance by an ultra-short transducer. After gradually approaching the recovery ball, it is optically guided from a close distance by a watertight camera. When the recovery ball contacts the guide rod, it slides into the frame under the guidance of the guide rod. S3, as the underwater robot continues to move forward, the recovery ball moves along the guide rod and is pushed into the frame. The recovery ball slides down the guide rod until it contacts the load-bearing structure. The recovery ball blocks the infrared light path, and the positioning detection sensor is triggered, outputting a high-level capture signal. S4. After receiving the high-level capture signal, the control unit immediately sends a reverse drive command to the drive unit to control the DC geared motor to reverse and drive the push rod to move backward. While retracting the guide rod, the capture claw closes, locking the recovery ball between the load-bearing structure and the capture claw. When the capture claw is fully closed, the locking position switch is triggered, and a locking success signal is fed back to the control unit, and the motor stops and locks. S5: The recovery ball and recovery cable establish a reliable connection with the docking system, the recovery cable tightens, the recovery ball fits tightly with the load-bearing structure, the pressure sensor data is normal, and the docking is completed; when release is required, the DC motor rotates forward, the push rod moves forward, the capture claw opens, the guide rod opens, and the underwater robot can detach from the recovery docking system.

[0037] The recovery docking method also includes a three-level anomaly handling process, which addresses three common anomalies: capture failure, locking failure, and disengagement. Handling capture failure: If the positioning detection sensor does not detect a trigger signal within 10 seconds, it is determined that the capture has failed; the control unit keeps the mechanism in the open state, the underwater robot automatically retreats 20m, readjusts its course and depth, and then re-enters the guidance phase. It can be retried up to 3 times. If the capture fails 3 or more times, a distress signal is sent to the mother ship. Locking failure handling: If the positioning detection sensor has been triggered, but the locking positioning switch does not provide a feedback signal within 5 seconds, it is determined that the locking has failed; the control unit immediately drives the motor to rotate forward, opens the capture claw, and the underwater robot retreats 20m to retry, with a maximum of 3 retries. If the locking fails 3 or more times, a distress signal is sent to the mother ship. Disengagement handling: If the pressure sensor detects that the tension suddenly drops below 10% of the threshold, it is determined to be disengaged; the control unit immediately drives the motor to rotate forward, opens the capture claw to release the residual cable, and the underwater robot automatically retreats and re-enters the acoustic guidance stage.

[0038] The working principle of an underwater robot capture-type autonomous recovery docking system and method in this embodiment of the invention is as follows: Based on the collaborative design of a flat main body, a guiding mechanism, a capture mechanism, a single drive mechanism, and a load-bearing structure, the docking device structure is integrated with the autonomous recovery operation method, enabling the synchronous operation of the guiding function and the capture function. It can adapt to the synchronous characteristics of the single drive mechanism, achieving a compact, low-resistance, and highly reliable autonomous docking recovery. At the same time, it provides a repeatable docking operation process and a three-level anomaly handling process, forming a two-level guidance mode that is both near and far. It is compatible with various operating platforms, requires no manual intervention, improves the efficiency of the recovery operation, ensures smooth docking, and has better maneuverability and longer endurance.

[0039] In this application, an integrated design approach combining structure and method is adopted. The docking system achieves synchronous operation of guidance and capture functions through a single drive source. The docking method is designed based on the mechanical characteristics of the docking system, with a standardized five-stage operation process and a three-level anomaly handling process, forming a complete autonomous recovery technical solution.

[0040] In the overall solution, the recycling docking system includes: a flat main body, a frame, a guiding mechanism, a capture mechanism, a single drive mechanism, and a load-bearing structure arranged in a coordinated manner; The frame is fixed inside the flat main body to form an integral support frame. The guiding mechanism and the capture mechanism are hinged to the front end of the frame and arranged symmetrically on the left and right, respectively undertaking the functions of position correction and locking of the retrieved ball. The single drive mechanism is fixed to the rear end of the frame and its output end is simultaneously connected to the guiding mechanism and the capture mechanism, providing power to the guiding mechanism and the capture mechanism to achieve precise synchronization of their actions. The load-bearing structure is welded and fixed to the center position of the front end of the frame to bear the retrieved ball and all tensile loads during the retrieval process, so as to protect the capture mechanism from damage.

[0041] Specifically, the flat body 1 is composed of a flat upper shell 103 and a flat lower shell 104 fastened together, and the whole is streamlined. The front of the flat upper shell has a mounting hole, and the watertight camera 101 is fixed in the hole by screws. An O-ring is provided at the opening to achieve radial sealing. The front of the flat lower shell has an integrally injection molded threaded mounting seat, and the ultra-short transducer 102 is screwed into the mounting seat by threads. The wiring terminal is connected to the internal cable through a watertight connector.

[0042] The frame 6 is CNC machined from aluminum alloy and includes a bow arc frame 601, four bow section connecting rods 602, a front frame 603, and a stern frame 604. The front end of the bow arc frame 601 is arc-shaped and is fixedly connected to the front frame 603 by countersunk screws. The front frame 603 and the stern frame 604 are connected and fixed by the bow section connecting rods 602. The two ends of the bow section connecting rods 602 are respectively inserted into the corresponding insertion holes of the front frame 603 and the stern frame 604 and locked with screws. The front inner side of the flat upper shell 103 and the flat lower shell 104 is provided with positioning bosses, which are fitted and positioned with the grooves on the upper and lower edges of the bow arc frame 601.

[0043] The guiding mechanism 2 includes guide rods 201 and guide rod connecting rods 202 arranged symmetrically on both sides. The rear end of the middle section of each guide rod 201 is rotatably connected to both sides of the front end of the bow arc frame 601 via a first hinge shaft 8. The front end of the guide rod 201 and the front end of the guide rod connecting rod 202 are hinged via a second hinge shaft 9. The lower rear end of the guide rod connecting rod 202 contacts the front end face of the push rod 4024. The front end of the guide rod 201 is provided with an outwardly inclined guide surface to increase the guiding range and reduce the impact force when colliding with the recovered ball.

[0044] The capture mechanism 3 includes a capture claw 301 hinged to the bow arc frame 601 and capable of opening and closing, a capture claw locking hook 302, and a position detection sensor 303. There are two capture claws 301, arranged symmetrically on the left and right. The middle part of each capture claw 301 is rotatably connected to both sides of the bow arc frame 601 through a first hinge shaft 8, which is used to close when the recovery ball 7 reaches the preset position and lock it inside the bow arc frame 601. The middle part of the capture claw locking hook 302 is hinged to the bow arc frame 601 through a third hinge shaft 10. One end of the hook contacts the rear end of the capture claw 301, and the other end forms an inclined contact with the upper rear end of the guide rod connecting rod 202. The position detection sensor 303 is an infrared sensor, embedded in the mounting groove at the front of the bow arc frame 601, and located above the load-bearing structure 5. When the recovery ball 7 moves along the guide channel to contact the load-bearing structure 5, the ball just blocks the infrared light path, and the infrared receiver outputs a high-level signal, indicating that the recovery ball has reached its position.

[0045] For the single-drive mechanism 4, mounted on the tail frame 604, it includes a drive unit 401, a transmission unit 402, a control unit 403, and a sealing sleeve 404. The drive unit 401 is a DC geared motor, and an aluminum alloy sealing sleeve 404 is provided on its exterior. The rear end of the sealing sleeve 404 is fixedly connected to the tail frame 604 by a flange and screws. The output shaft of the DC motor extends out of the end face of the sealing sleeve 404 and is connected to a lead screw 4022 through a coupling 4021. The lead screw 4022 is threadedly engaged with a first nut 4023, and a second nut 4025 is fixedly connected to a push rod 4024. The push rod 4024 is a rod that slides in the front-back direction. Its front end contacts the guide rod connecting rod 202 and is used to drive the expansion and contraction of the guide rod 201 and the closing and opening of the capture claw 301. The control unit 403 is integrated in the rear of the main body and includes a power supply 4031, a main control circuit board 4032, a vision computer 4033, and a video acquisition unit 4034. The main control circuit board 4032 is electrically connected to the drive source 401 and the position detection sensor 303, and is used to receive the position detection signal and control the forward and reverse rotation of the motor. The vision computer 4033 and the video acquisition unit 4034 are connected to the watertight camera 101 on the front of the main body, and are used to identify and record the position of the recovery ball in real time during the recovery process to assist in guidance.

[0046] Specifically, when the drive unit drives the transmission unit to move the push rod forward, the push rod pushes the guide rod connecting rod to rotate around the second hinge axis, causing the guide rod to open outward to the working angle. The inclined surface at the rear end of the guide rod connecting rod disengages from the capture claw hook. Under its own gravity, the hook rotates around the third hinge axis, releasing the locking pin at the rear end of the capture claw. The capture claw then fully opens, and the docking system enters the capture-ready state. When the drive unit rotates in the opposite direction to move the push rod backward, the push rod pulls the guide rod connecting rod to rotate in the opposite direction, causing the guide rod to retract inward into the flat body. At the same time, the inclined surface at the rear end of the guide rod connecting rod presses the capture claw hook, causing the hook to rotate around the third hinge axis. Its hook head hooks the locking pin at the rear end of the capture claw and drives the capture claw to close inward, firmly locking the recovery ball between the load-bearing structure and the capture claw.

[0047] The load-bearing structure 5, a metal block, is fixedly connected to the lower center of the bow arc-shaped frame by welding. Its front face has an arc-shaped concave surface, the radius of curvature of which matches the radius of the recovery ball 7. When the capture claw 301 closes, the recovery ball 7 is confined between the load-bearing structure 5 and the capture claw 301. When the retrieval cable is tightened, the recovery ball 7 fits tightly against the arc-shaped concave surface of the load-bearing structure 5, forming a large-area contact and preventing the capture claw 301 from bearing excessive tension.

[0048] Correspondingly, the recycling docking method includes the following steps: S1 Preparation Phase: Initially, the underwater robot is in a navigation state. Five minutes before reaching the recovery area, the docking device is powered on and started. The control unit 403 sequentially checks whether the power supply voltage, motor current, sensor signals, and communication link are normal. After the self-test passes, the control unit 403 sends a forward drive command to the drive unit 401. The drive source 401 drives the push rod 4024 to move forward, the guide rod 201 opens to a preset angle, and at the same time, the capture claw hook 302 unlocks, the capture claw 301 opens, and the docking system enters the capture state.

[0049] S2 Guidance Phase: The underwater robot carrying the recovery ball 7 travels towards the docking system at a preset speed. When the recovery ball 7 approaches the docking system, due to navigation deviation, the recovery ball 7 may first contact the left or right guide rod 201. Guided by the inclined surface of the guide rod 201, the recovery ball 7 slides along the guide rod 201 towards the center of the frame 6 and enters the frame.

[0050] S3 Triggering Phase: As the underwater robot continues to move forward, the recovery ball 7 moves along the guide rod 201 and is pushed into the frame 6 until it contacts the load-bearing structure 5. At this time, the recovery ball 7 blocks the infrared light path, and the positioning detection sensor 303 outputs a high-level trigger signal.

[0051] S4 Capture Phase: Upon receiving the trigger signal, the control unit 403 immediately sends a reverse drive command to the drive unit 401, controlling the DC motor to reverse and drive the push rod 4024 to move backward. Simultaneously, the guide rod 201 retracts, closing the capture claw 301 and locking the recovery ball 7 between the load-bearing structure 5 and the capture claw 301. When the capture claw 301 is fully closed, the locking position switch is triggered, sending a successful locking signal to the control unit 403, and the motor stops and locks.

[0052] S5 Recovery Phase: The recovery ball 7 is firmly secured between the load-bearing structure 5 and the capture claw 301. The recovery ball 7 and the load-bearing structure 5 are tightly fitted together, completing the docking.

[0053] When release is required, the DC motor rotates forward, the push rod 4024 moves forward, the capture claw 301 opens, the guide rod 201 opens, and the underwater robot can detach from the recovery docking system.

[0054] To improve the reliability of the recovery process and cope with various abnormal situations that may occur under complex sea conditions, this invention designs a three-level anomaly handling process: 1. Handling of capture failure: If the positioning sensor 303 does not detect a trigger signal within 10 seconds, the capture is deemed to have failed. The control unit 403 keeps the mechanism in the open state, and the underwater robot automatically retreats 20m, readjusts its course and depth, and then re-enters the guidance phase. It can be retried up to 3 times. If the capture fails 3 or more times, a distress signal will be sent to the mother ship. 2. Locking Failure Handling: If the positioning detection sensor has been triggered, but the locking positioning switch does not provide a feedback signal within 5 seconds, it is determined that the locking has failed. The control unit 403 immediately drives the motor to rotate forward, opens the capture claw 301, and the underwater robot retreats 20m to retry. It can retry a maximum of 3 times. If the locking fails 3 or more times, a distress signal will be sent to the mother ship. 3. Unhooking process: If the pressure sensor 501 detects that the tension suddenly drops below 10% of the threshold, it is determined that the hook has been unhooked; the control unit 403 immediately drives the motor to rotate forward, opens the capture claw to release the residual cable, and the underwater robot automatically retreats and re-enters the acoustic guidance stage.

[0055] All anomaly handling is completed automatically by the system without manual intervention, significantly improving the recovery success rate and the system's autonomy. It should be noted that an elastic pad is provided on the inside of the capture claw to increase the friction between it and the recovery ball and to protect the surface of the recovery ball.

[0056] In summary, the underwater robot capture-type autonomous recovery and docking system and method in this embodiment of the invention is based on the collaborative design of a flat main body, a guiding mechanism, a capture mechanism, a single drive mechanism, and a load-bearing structure. It integrates the docking device structure with the autonomous recovery operation method, enabling the synchronous operation of the guiding and capture functions. It can adapt to the synchronous characteristics of the single drive mechanism, achieving a compact, low-resistance, and highly reliable autonomous docking and recovery. At the same time, it provides a repeatable docking operation process and a three-level anomaly handling process, forming a two-level guidance mode that is compatible with various operating platforms. It does not require manual intervention, improves the efficiency of recovery operations, ensures smooth docking, and has better maneuverability and longer endurance.

[0057] The above specific embodiments should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, any alternative improvements or modifications made to the embodiments of the present invention shall fall within the scope of protection of the present invention.

[0058] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. An underwater robot capture-type autonomous recovery and docking system, characterized in that, The recycling docking system includes: a flat main body, a frame, a guiding mechanism, a capture mechanism, a single drive mechanism, and a load-bearing structure arranged in a coordinated manner; The frame is fixed inside the flat main body to form an integral support frame. The guiding mechanism and the capture mechanism are hinged to the front end of the frame and arranged symmetrically on the left and right, respectively undertaking the functions of position correction and locking of the retrieved ball. The single drive mechanism is fixed to the rear end of the frame and its output end is simultaneously connected to the guiding mechanism and the capture mechanism, providing power to the guiding mechanism and the capture mechanism to achieve precise synchronization of their actions. The load-bearing structure is welded and fixed to the center position of the front end of the frame to bear the retrieved ball and all tensile loads during the retrieval process, so as to protect the capture mechanism from damage.

2. The underwater robot capture-type autonomous recovery and docking system according to claim 1, characterized in that: The flat body has a streamlined design and is formed by a flat upper shell and a flat lower shell. A watertight camera and an ultra-short transducer are installed on the front side respectively. The frame includes a bow arc-shaped frame, a bow section connecting rod, a front frame, and a stern frame. The bow arc-shaped frame is fixedly connected to the front frame with screws, and the front frame and the stern frame are fixedly connected with the bow section connecting rod. The bow arc-shaped frame is located at the foremost end of the frame and matches the streamlined profile of the front end of the flat main body to reduce fluid resistance. The front frame and the bow arc-shaped frame are fixedly connected with multiple countersunk screws to provide a stable mounting position for the guiding mechanism and the capture mechanism. The stern frame is used to install a single drive mechanism and is connected and fixed between the front frame and the stern frame by four parallel bow section connecting rods. The two ends of the connecting rods are inserted into the corresponding holes of the front and rear frames and locked with set screws.

3. The underwater robot capture-type autonomous recovery and docking system according to claim 2, characterized in that: The front of the flat upper shell and the flat lower shell are fitted and positioned with the upper and lower edges of the bow arc frame. The middle part is fixed to the front frame with screws, and the rear part is fixed to the tail frame with screws, forming a closed installation cavity to ensure the strength and rigidity of the overall structure and protect the internal mechanism from seawater corrosion. A dedicated mounting hole is provided at the front of the flat upper shell. The watertight camera is fixed in the hole through a sealing structure and is used to collect real-time image information of the recovered ball during the close-range recovery phase, providing data support for optical guidance. A transducer mounting base is integrally injection molded at the front of the flat lower shell. The ultra-short transducer is fixed in the base through a threaded connection and is used to conduct acoustic communication and positioning with the mother ship during the long-range recovery phase, enabling large-area target search.

4. The underwater robot capture-type autonomous recovery and docking system according to claim 2, characterized in that: The guiding mechanism includes guide rods and guide rod connecting rods arranged symmetrically on the left and right sides, and the guide rods and guide rod connecting rods are configured and used together; the rear end of the guide rod is rotatably connected to a hinge support fixed to the bow arc frame through a first hinge shaft, which is used to open underwater to form a funnel-shaped area to guide the recovery ball at the end of the recovery cable into the docking system; the front end of the guide rod is hinged to the front end of the guide rod connecting rod through a second hinge shaft; the lower part of the rear end of the guide rod connecting rod has a flat surface that forms surface contact with the front end of the push rod of the single drive mechanism.

5. The underwater robot capture-type autonomous recovery and docking system according to claim 4, characterized in that: The capture mechanism includes two capture claws, a capture claw locking hook, and a positioning detection sensor; the middle part of each capture claw is rotatably connected to a hinge support fixed to the bow arc frame via a first hinge shaft, which is used to rotate around the shaft to realize the opening and closing action; a cylindrical locking pin is provided at the rear end of the capture claw, which is used to cooperate with the capture claw locking hook to realize locking. The capture claw hook is rotatably connected to the bow arc frame via a third hinge shaft. One end is machined into a hook shape to hook the cylindrical locking pin at the rear end of the capture claw; the other end is machined into an inclined sliding surface to form a sliding contact with the corresponding inclined surface at the upper rear end of the guide rod connecting rod, thereby achieving mechanical linkage. The positioning detection sensor is fixedly installed in the front mounting slot of the bow arc frame via a slot and is located above the load-bearing structure. The positioning detection sensor is an infrared sensor, and its detection light path passes exactly through the preset positioning position of the recovery ball. When the recovery ball moves along the guide channel to contact the load-bearing structure, it blocks the infrared light path and generates a high-level trigger signal.

6. The underwater robot capture-type autonomous recovery and docking system according to claim 4, characterized in that: The single drive mechanism includes a drive unit, a transmission unit, a control unit, and a sealing sleeve; the drive unit is a DC geared motor, and a sealing sleeve is provided on its exterior. The sealing sleeve is fixedly connected to the tail frame by a flange and screws. The transmission unit includes a coupling, a lead screw, a nut, and a push rod. The output shaft of the DC geared motor is connected to the input end of the reducer. The output shaft of the DC geared motor is fixedly connected to one end of the lead screw via the coupling. The first nut is threaded into the other end of the lead screw. The second nut is fixedly connected to the rear end of the push rod. The front end of the push rod serves as the output end of the transmission assembly and forms surface contact with the lower rear end of the guide rod connecting rod. The control unit is fixedly installed on a preset mounting position on the tail frame via a slot. The control unit includes a power supply, a main control circuit board, a vision computer, and a video acquisition unit. It is used to receive position detection sensor signals and pressure sensor signals, and output forward and reverse rotation commands to the drive unit according to the control logic to control the operation of the DC geared motor.

7. The underwater robot capture-type autonomous recovery and docking system according to claim 6, characterized in that: When the drive unit drives the transmission unit to move the push rod forward, the push rod pushes the guide rod connecting rod to rotate around the second hinge axis, causing the guide rod to open outward to the working angle. The inclined surface at the rear end of the guide rod connecting rod disengages from the capture claw hook. Under its own gravity, the hook rotates around the third hinge axis, releasing the locking pin at the rear end of the capture claw. The capture claw then fully opens, and the docking system enters the capture-ready state. When the drive unit rotates in the opposite direction to move the push rod backward, the push rod pulls the guide rod connecting rod to rotate in the opposite direction, causing the guide rod to retract inward into the flat body. At the same time, the inclined surface at the rear end of the guide rod connecting rod presses the capture claw hook, causing the hook to rotate around the third hinge axis. Its hook head hooks the locking pin at the rear end of the capture claw and drives the capture claw to close inward, firmly locking the recovery ball between the load-bearing structure and the capture claw.

8. The underwater robot capture-type autonomous recovery and docking system according to claim 7, characterized in that: The load-bearing structure is fixedly connected to the lower center of the bow arc frame by welding. It is a metal block with an arc concave surface that matches the recovery ball, so as to form a surface contact with the recovery ball during towing and bear the pulling force during recovery and towing. The load-bearing structure is equipped with a pressure sensor to detect the recovery pressure of the recovery ball.

9. A method for autonomous capture and docking of an underwater robot, characterized in that, The recycling docking method includes the following steps: S1. Five minutes before the underwater robot reaches the recovery area, the docking system is powered on and started. The control unit checks the power supply voltage, motor current, sensor signals and communication links in sequence to ensure they are normal. After the self-test is passed, the control unit sends a forward drive command to the drive unit, which drives the push rod to move forward and opens the guide rod to the working angle. At the same time, the capture claw lock hook is unlocked, and the capture claw opens and enters the unlocked state. The docking system enters the capture state. S2, the underwater robot carrying the recovery ball sails toward the docking system at a preset speed. The underwater robot is acoustically located and guided from a distance by an ultra-short transducer. After gradually approaching the recovery ball, it is optically guided from a close distance by a watertight camera. When the recovery ball contacts the guide rod, it slides into the frame under the guidance of the guide rod. S3, as the underwater robot continues to move forward, the recovery ball moves along the guide rod and is pushed into the frame. The recovery ball slides down the guide rod until it contacts the load-bearing structure. The recovery ball blocks the infrared light path, and the positioning detection sensor is triggered, outputting a high-level capture signal. S4. After receiving the high-level capture signal, the control unit immediately sends a reverse drive command to the drive unit to control the DC geared motor to reverse and drive the push rod to move backward. While retracting the guide rod, the capture claw closes, locking the recovery ball between the load-bearing structure and the capture claw. When the capture claw is fully closed, the locking position switch is triggered, and a locking success signal is fed back to the control unit, and the motor stops and locks. S5: The recovery ball and recovery cable establish a reliable connection with the docking system, the recovery cable tightens, the recovery ball fits tightly with the load-bearing structure, the pressure sensor data is normal, and the docking is completed; when release is required, the DC motor rotates forward, the push rod moves forward, the capture claw opens, the guide rod opens, and the underwater robot can detach from the recovery docking system.

10. A method for autonomous capture and docking of an underwater robot according to claim 9, characterized in that, The recovery docking method also includes a three-level anomaly handling process, which addresses three common anomalies: capture failure, locking failure, and disengagement. Handling capture failure: If the positioning detection sensor does not detect a trigger signal within 10 seconds, it is determined that the capture has failed; the control unit keeps the mechanism in the open state, the underwater robot automatically retreats 20m, readjusts its course and depth, and then re-enters the guidance phase. It can be retried up to 3 times. If the capture fails 3 or more times, a distress signal is sent to the mother ship. Locking failure handling: If the positioning detection sensor has been triggered, but the locking positioning switch does not provide a feedback signal within 5 seconds, it is determined that the locking has failed; the control unit immediately drives the motor to rotate forward, opens the capture claw, and the underwater robot retreats 20m to retry, with a maximum of 3 retries. If the locking fails 3 or more times, a distress signal is sent to the mother ship. Disengagement handling: If the pressure sensor detects that the tension suddenly drops below 10% of the threshold, it is determined to be disengaged; the control unit immediately drives the motor to rotate forward, opens the capture claw to release the residual cable, and the underwater robot automatically retreats and re-enters the acoustic guidance stage.

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