A precision docking mechanism and control method for an underwater robot

Abstract

The application belongs to the field of underwater robots and relates to a precise docking mechanism and control method of an underwater robot. The mechanism comprises a receiving device and a docking device. The receiving device comprises a pressure-bearing cabin and control and power supply modules, locking electromagnets, an image acquisition device, a rotary positioning device and a centering device arranged in sequence in the pressure-bearing cabin. The image acquisition device is used to collect the real-time position of a docking head and feed back to the control and power supply modules. The control and power supply modules control the rotary positioning device to adjust the angle between the docking head and the rotary positioning device, control the centering device to keep the docking head coaxial with the rotary positioning device and control the locking electromagnets to be powered on to realize the locking and fixing between the docking head and the rotary positioning device. In this way, the precise fine adjustment is realized through the image recognition and the spring magnet combined system of the centering device, the speed and precision are improved, the dynamic correction is realized, the closed-loop control of high-precision docking in a poor light environment in the deep sea is realized and the underwater robot formation cooperative operation has a very positive significance.

Description

Technical Field

[0001] This invention belongs to the field of underwater robots, specifically relating to a precise docking mechanism and control method for underwater robots. Background Technology

[0002] The underwater environment is complex and changeable. In areas with good conditions and ample space, manned submarines are often used for exploration. However, in some waters with strong currents, underwater robots are required due to space or environmental constraints.

[0003] The operational efficiency of a single underwater robot is limited, and different types of underwater robots have varying operational capabilities. The future development trend is for underwater robots to evolve from individual operations to swarm operations, leveraging the advantages of different robot types to improve detection efficiency. With the increasing emphasis on long-term and comprehensive ocean observation, building collaborative operational systems using multiple underwater robot platforms such as AUVs, ROVs, and ARVs to observe and study the ocean from different depths, scales, and ocean parameters has become an inevitable trend in the underwater robotics industry.

[0004] To enable swarm operations of underwater robots, two or more robots need to be docked before underwater operations can begin. Currently, there are two main methods for this:

[0005] The first method is docking on land, but the on-shore method has poor concealment and high docking risk, and manual docking is prone to collisions.

[0006] The second type is underwater fixed connection. Although the docking risk is small, the existing docking docks are relatively large and have poor flexibility. High concealment is required during docking, and the use of sonar communication should be minimized. Otherwise, they can easily become targets of deep-sea attacks in special circumstances. Moreover, being fixed in the deep-sea environment for a long time will result in the attachment of marine organisms and significant corrosion from the marine environment. The mother ship release and recovery process is highly intensive and dangerous, which greatly limits the engineering application of AUVs.

[0007] How to enable multiple underwater robots to dock and separate freely and precisely underwater, in order to improve the flexibility and maneuverability of underwater robot swarms, is an urgent problem to be solved. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention proposes a precise docking mechanism and control method for underwater robots, which can quickly and conveniently achieve precise docking and flexible operation of underwater robots underwater, greatly improving the flexibility and maneuverability of underwater robot swarm formations.

[0009] The proposed solution is as follows:

[0010] On one hand, this invention proposes a precise docking mechanism for an underwater robot, including a receiving device installed on an underwater device A and a docking device installed on an underwater device B. The docking device includes a docking joint and a docking fixing base installed on the docking joint, the docking fixing base being used to connect the underwater robot A. The receiving device includes a receiving fixing base and a pressure chamber, the receiving fixing base being used to connect the underwater robot B. The receiving device also includes a control and power supply module, a locking electromagnet, an image acquisition device, a rotation positioning device, and an alignment device sequentially arranged in the pressure chamber. Both the rotation positioning device and the alignment device have channels for inserting the docking joint. The image acquisition device is used to collect the real-time position of the docking joint and feed it back to the control and power supply module. The control and power supply module controls the rotation positioning device to adjust the rotation angle between it and the docking joint. The control and power supply module controls the alignment device to keep the docking joint and the rotation positioning device coaxial. The control and power supply module controls the locking electromagnet to be energized to attract the docking joint, thereby locking and fixing the docking joint and the rotation positioning device.

[0011] Furthermore, the image acquisition device includes a camera mounting bracket, an industrial camera, and a light source. The light source and the industrial camera are both fixed on the camera mounting bracket, which is installed inside the pressure chamber. The industrial camera and the light source are aligned with the rotary positioning device.

[0012] Furthermore, the rotary positioning device includes a slip ring motor and a connecting cap. The rotor of the slip ring motor is connected to the connecting cap to drive the connecting cap to rotate. The side wall of the slip ring motor is connected to the pressure chamber. The connecting cap is configured with a channel structure that is open at one end and closed at the other end. The outer contour of the channel structure is adapted to the upper part of the docking head. The closed end of the channel structure is made of a light-transmitting transparent material.

[0013] Furthermore, the closed end of the channel structure extends a plug towards the connector end, and the top of the connector has a slot adapted to the plug to restrict the radial and circumferential movement of the connector.

[0014] Furthermore, the alignment device includes a docking groove, a tension spring, a corrective electromagnet, a guide connecting rod, and a permanent magnet. The docking groove is connected to the stator of the slip ring motor. Several brackets are evenly distributed circumferentially around the end of the docking groove away from the slip ring motor. A corrective electromagnet is installed on each bracket. The guide connecting rod includes branch rods of the same number as the brackets. The permanent magnet is embedded in the end of the branch rod near the bracket. The branch rod and the corresponding bracket are connected by the tension spring. The alignment device has a channel for inserting the docking head, and the channel is located at the center of the guide connecting rod.

[0015] Furthermore, the centering device also includes a second locking part to restrict the axial movement of the coupling.

[0016] Furthermore, the second locking part includes several micro servo motors and several fixing buckles. The micro servo motors are installed on the docking slot near the slip ring motor end. The fixing buckles are connected to the micro servo motors. The surface of the docking joint is provided with an annular groove that matches the fixing buckle. The micro servo motors drive the fixing buckles to engage with or move away from the annular groove.

[0017] On the other hand, the present invention also proposes a precise docking control method for an underwater robot, applied to the precise docking mechanism of the aforementioned underwater robot, comprising the following steps:

[0018] S1. The connector is inserted into the guide connecting rod of the centering device. The image acquisition device acquires the image between the connector and the guide connecting rod, as well as the image between the connector and the connecting cap of the rotary positioning device, and feeds the acquired data back to the controller of the control and power supply module.

[0019] S2. The controller calculates the center distance between the connector and the guide connecting rod, decouples the center distance to a two-dimensional coordinate system, and obtains the first position difference in the two-dimensional coordinate system, i.e., the x and y directions; the controller calculates the center distance between the connector and the connecting cap, decouples the center distance to a two-dimensional coordinate system, and obtains the second position difference in the two-dimensional coordinate system, i.e., the x and y directions.

[0020] S3. Based on the difference between the first and second positions in step S2 and the balance relationship formula between the electromagnet and the tension spring built into the controller, the current value of the correction electromagnet supplied to the centering device is obtained. The controller adjusts the extension and retraction of the tension spring by changing the current value of the correction electromagnet in real time to eliminate the difference between the first and second positions.

[0021] S4. After the difference between the first and second positions is eliminated, the image acquisition device acquires an image between the slot of the connector and the plug of the rotary positioning device, and feeds back the acquired data to the controller of the control and power supply module; the controller calculates the included angle between the slot and the plug.

[0022] S5. According to the included angle in step S4, the controller adjusts the operation of the slip ring motor of the rotary positioning device. The rotation of the slip ring motor drives the connecting cap to rotate to the position where the included angle is zero.

[0023] S6. The controller controls the locking electromagnet to be energized, which attracts the top of the connector to the position of the connector cap. The plug inside the connector cap is tightly connected to the socket on the top of the connector to restrict the radial and circumferential movement of the connector.

[0024] S7. The controller controls the micro servo motor of the alignment device to work. The micro servo motor drives the fixed buckle to rotate towards the center of the arc, thereby fixing and locking the groove of the docking head and restricting the axial movement of the docking head.

[0025] Furthermore, in step S3,

[0026] The equilibrium formula between the electromagnet and the tension spring is:

[0027] (1);

[0028] Where μ0 is the free permeability, with a value of ;

[0029] m1 is the magnetic moment of the permanent magnet;

[0030] N is the number of turns of the electromagnetic coil;

[0031] I represents the electromagnet current;

[0032] S is the cross-sectional area of ​​the electromagnet coil;

[0033] This refers to the docking distance;

[0034] k is the spring constant of the tension spring;

[0035] This refers to the deformation of the tension spring due to the force applied.

[0036] Docking distance formula: (2);

[0037] Where d is the distance between the corrected electromagnet and the position of a permanent magnet on a bracket on the guide connecting rod;

[0038] dx represents the positional difference between a specific bracket and its connector;

[0039] (3);

[0040] Substituting formulas (2) and (3) into formula (1), we obtain the formula for the magnitude of the current supplied by the controller to the correction electromagnet:

[0041] (4).

[0042] Compared with the prior art, the advantages of the present invention are as follows:

[0043] This invention is primarily applicable when two objects are already relatively parallel in posture, but precise docking is impossible due to seawater disturbance. The invention incorporates a control and power supply module, a locking electromagnet, an image acquisition device, a rotation positioning device, and a centering device within the pressure chamber of the receiving device. The precise docking mechanism of this invention can achieve precise fine-tuning through a combination of image recognition and a spring-magnet system, improving docking speed and accuracy. This allows the entire docking device to dynamically correct itself against the object to be docked, enabling closed-loop control for high-precision docking in the poor light conditions of the deep sea. This has significant implications for future collaborative operations involving multiple underwater robots in formation.

[0044] The precision docking mechanism of this invention features an innovative structural design, a reasonable and compact layout, a simple structure, low cost, and easy manufacturing. It eliminates the manual docking step, reduces the difficulty of underwater docking tasks, and improves the flexibility of the entire system. It can achieve precise docking at any location in the deep sea, with lower adjustment difficulty and easier calculation. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the overall structure (connection state) of the precision docking mechanism according to Embodiment 1 of the present invention.

[0046] Figure 2 This is a schematic diagram of the overall structure (separated state) of the precision docking mechanism according to Embodiment 1 of the present invention.

[0047] Figure 3 This is a longitudinal cross-sectional view of the precision docking mechanism according to Embodiment 1 of the present invention;

[0048] Figure 4 This is an exploded structural diagram of the precision docking mechanism according to Embodiment 1 of the present invention;

[0049] Figure 5 This is a schematic diagram of the connecting cap according to Embodiment 1 of the present invention;

[0050] Figure 6 This is a schematic diagram of the structure of a centering device according to an embodiment of the present invention;

[0051] Figure 7 This is a partial structural diagram of the precision docking mechanism according to Embodiment 1 of the present invention;

[0052] Figure 8 This is a flowchart illustrating the precise docking control method of Embodiment 2 of the present invention;

[0053] Figure 9 This is a schematic diagram of the image processing process in Embodiment 2 of the present invention;

[0054] Figure 10 This is the control result output data of Embodiment 2 of the present invention;

[0055] Figure 11 This is the comparative output data of the control results in Embodiment 2 of the present invention.

[0056] In the above figures:

[0057] 100. Receiving device; 110. Receiving fixed base; 120. Pressure chamber; 130. Control and power supply module; 140. Locking electromagnet; 150. Image acquisition device; 151. Camera mounting bracket; 152. Industrial camera; 153. Light source; 160. Rotary positioning device; 161. Slip ring motor; 162. Connecting cap; 1621. Channel structure; 1622. Plug; 170. Alignment device; 171. Docking groove; 1711. Bracket; 172. Tension spring; 173. Correction electromagnet; 174. Guide connecting rod; 1741. Branch rod; 175. Permanent magnet; 176. Second locking part; 1761. Miniature servo motor; 1762. Fixing buckle; 200. Docking device; 210. Docking joint; 211. Ring groove; 212. Slot; 220. Docking fixed base. Detailed Implementation

[0058] To facilitate understanding of the present invention by those skilled in the art, specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0059] The precise docking mechanism and control method of the present invention are particularly suitable for scenarios where the receiving device 100 and the docking device 200, and the interconnected underwater main body devices such as underwater robots, have achieved pose data synchronization before docking, that is, the main body and the connected body have achieved the same posture before docking, but there is still a small distance, and due to the underwater undulating environment, it is difficult to achieve a stable docking state. The precise docking mechanism of the present invention is mainly to solve the problems in such specific environments and improve the docking accuracy and docking speed in the critical docking state.

[0060] Example 1

[0061] like Figures 1-7 As shown, the present invention discloses a precise docking mechanism for underwater robots, including a receiving device 100 and a docking device 200. The two devices are respectively installed on different underwater robots. When docking is required, the docking device 200 is inserted into the receiving device 100 to achieve precise docking of the two underwater devices.

[0062] The docking device 200 includes a docking joint 210 and a docking fixing base 220, which are connected by threads. The docking fixing base 220 is fixedly connected to the underwater robot A (not shown in the figure) by bolts. The receiving device 100 includes a receiving fixing base 110 and a pressure chamber 120, which are connected by threads. The receiving fixing base 110 is fixedly connected to the underwater robot B (not shown in the figure) by bolts. The receiving device 100 also includes a control and power supply module 130, a locking electromagnet 140, an image acquisition device 150, a rotation positioning device 160, and an alignment device 170, which are sequentially arranged in the pressure chamber 120. The rotation positioning device 160 and the alignment device 170 are both provided with channels for inserting the connector 210. The image acquisition device 150 is used to collect the real-time position of the connector 210 and feed it back to the control and power supply module 130. The control and power supply module 130 controls the rotation positioning device 160 to adjust the rotation angle between it and the connector 210. The control and power supply module 130 controls the alignment device 170 to keep the connector 210 and the rotation positioning device 160 coaxial. The control and power supply module 130 controls the locking electromagnet 140 to be energized to attract the connector 210 and achieve locking and fixing between the connector 210 and the rotation positioning device 160.

[0063] Specifically, the image acquisition device 150 includes a camera mounting bracket 151, an industrial camera 152, and a light source 153. The light source 153 and the industrial camera 152 are both fixed on the camera mounting bracket 151. The camera mounting bracket 151 is installed inside the pressure chamber 120. The industrial camera 152 and the light source 153 are aligned with the rotation positioning device 160.

[0064] Specifically, the industrial camera 152 is fixedly connected to the camera mounting bracket 151 through the groove of the camera mounting bracket 151. The camera mounting bracket 151 has four through holes, and bolts pass through the four through holes to be fixedly connected to the pressure chamber 120.

[0065] The control and power supply module 130 includes an integrated controller and power supply unit. The interior of the pressure chamber 120 is a hollow through-hole, and a stepped hole is provided on the hollow through-hole. The control and power supply module 130 is limited and fixed through the stepped hole in the pressure chamber 120.

[0066] The rotary positioning device 160 includes a slip ring motor 161 and a connecting cap 162. The slip ring motor 161 includes a stator (outer ring) and a rotor (inner ring), and the stator and rotor rotate around each other via cylindrical needle roller bearings.

[0067] The rotor of the slip ring motor 161 is connected to the connecting cap 162 to drive the connecting cap 162 to rotate. The outer ring sidewall of the slip ring motor 161 is connected to the pressure chamber 120. In this embodiment, the sidewall of the pressure chamber 120 is provided with multiple threaded holes evenly distributed around it. The locking screw passes through the threaded holes and abuts against the outer ring sidewall of the slip ring motor 161 to achieve a fixed connection between the slip ring motor 161 and the pressure chamber 120. The connecting cap 162 is provided with a channel structure 1621 that is open at one end and closed at the other end. The outer contour of the channel structure 1621 is adapted to the upper part of the connector 210.

[0068] In order for the industrial camera 152 to see the connector 210, the closed end of the channel structure 1621 inside the connector cap 162 is made of a light-transmitting transparent material.

[0069] Furthermore, a plug 1622 extends from the closed end of the channel structure 1621 toward the end near the connector 210, and a slot 212 adapted to the plug 1622 is provided at the top of the connector 210 to restrict the radial and circumferential movement of the connector 210.

[0070] The stator of the slip ring motor 161 is connected to the alignment device 170. The alignment device 170 is used to adjust the mating joint 210 and the connecting cap 162 to be concentric.

[0071] The centering device 170 includes a docking groove 171, a tension spring 172, a corrective electromagnet 173, a guide connecting rod 174, and a permanent magnet 175. The docking groove 171 is connected to the stator of the slip ring motor 161. Several supports 1711 are evenly distributed circumferentially around the end of the docking groove 171 away from the slip ring motor 161. In this embodiment, there are four supports 1711, and each support 1711 is equipped with a corrective electromagnet 173. In this embodiment, the corrective electromagnet 173 is an 8mm diameter electromagnet, which is embedded in a pre-set recessed groove on the support 1711. The guide connecting rod 174 includes the same number of branch rods 1741 as the supports 1711, i.e., four branch rods 1741 in this embodiment. The central part where the four branch rods 1741 meet is a circular structure. The size of this circular structure is adapted to the mating joint 210 to allow the mating joint 210 to pass through smoothly. A permanent magnet 175 is embedded in the end of the branch rod 1741 near the bracket 1711. The permanent magnet 175 and the correction electromagnet 173 are positioned opposite each other and are used in conjunction. The branch rod 1741 and the corresponding bracket 1711 are connected by a tension spring 172. In this embodiment, hook rods are provided on the branch rod 1741 and the bracket 1711 to facilitate the connection of the tension spring 172.

[0072] To further enhance the locking effect, the centering device 170 also includes a second locking part 176 to restrict the axial movement of the coupling 210. Specifically, as shown... Figure 4As shown, the second locking part 176 includes several micro servo motors 1761 and several fixing buckles 1762. In this embodiment, there are two micro servo motors 1761, and each micro servo motor 1761 is connected to a fixing buckle 1762. The micro servo motors 1761 are installed on the docking slot 171 near the slip ring motor 161. The fixing buckles 1762 are connected to the micro servo motors 1761. The surface of the mating joint 210 has a circumferentially formed annular groove 211 that matches the fixing buckle 1762. The micro servo motors 1761 drive the fixing buckles 1762 to engage or disengage from the annular groove 211.

[0073] The locking magnet is used to provide locking force for locking the connector 210. In this embodiment, a 52mm diameter electromagnet is selected, which is limited and fixed by a stepped groove provided in the pressure chamber 120.

[0074] The connecting cap 162 is fixedly connected to the rotor (inner ring) of the slip ring motor 161, so that the connecting cap 162 can move in a circle around the docking groove 171. The connecting cap 162 is provided with a plug 1622 that is similar in shape to an electric plug 1622. When the slot 212 on the top of the connector 210 coincides with the position of the plug 1622, the locking magnet is energized, which attracts the connector 210 into the connecting cap 162, and the plug 1622 is inserted into the slot 212, thereby locking the connector 210.

[0075] Work process:

[0076] The docking device 200 gradually approaches the receiving device 100, and the mating connector 210 is inserted into the docking slot 171. The pattern acquisition device detects the position of the mating connector 210 in real time and feeds it back to the control and power supply module 130. The control and power supply module 130 controls the alignment device 170 to adjust the position of the mating connector 210 in real time so that the mating connector 210 is aligned with the connecting cap 162. Then, the control and power supply module 130 controls the rotation positioning device 160 to adjust the rotation angle of the mating connector 210 so that the plug 1622 and the slot 212 are at zero angle. After that, the control and power supply module 170... When the locking electromagnet 140 is energized, the connector 210 is attracted into the connector cap 162, and the plug 1622 is inserted into the slot 212. The proximity switch (not shown in the figure) embedded on the end of the plug 1622 outputs a contact signal. The controller of the control and power supply module 130 receives the contact signal and controls the micro servo motor 1761 of the second locking part 176 to work. The micro servo motor 1761 drives the fixing buckle 1762 to engage in the annular groove 211 of the connector 210, thereby realizing the precise docking of the underwater robot.

[0077] The present invention securely fixes all degrees of freedom of the connector 210 to the receiving device 100 through multiple locking mechanisms, including the plug 1622 socket, the fixing buckle 1762, and the annular groove 211. At the same time, it also has another function: when the connection device between the docking device 200 and the connector 210 needs to be connected, the rotation angle can be controlled as needed, and the connecting cap 162 will drive the connector 210 to achieve controllable rotation.

[0078] Example 2

[0079] like Figure 8 As shown, the present invention also provides a precise docking control method, comprising the following steps:

[0080] S1. The connector 210 is inserted into the guide connecting rod 174 of the centering device 170. The image acquisition device 150 acquires the image between the connector 210 and the guide connecting rod 174, as well as the image between the connector 210 and the connecting cap 162 of the rotary positioning device 160, and feeds the acquired data back to the controller of the control and power supply module 130.

[0081] S2. The controller calculates the center distance between the connector 210 and the guide connecting rod 174, decouples the center distance to a two-dimensional coordinate system, and obtains the first position difference in the two-dimensional coordinate system, i.e., the x and y directions. The controller calculates the center distance between the connector 210 and the connecting cap 162, decouples the center distance to a two-dimensional coordinate system, and obtains the second position difference in the two-dimensional coordinate system, i.e., the x and y directions.

[0082] S3. Based on the difference between the first and second positions in step S2 and the balance relationship formula of the electromagnet and tension spring 172 built into the controller, the current value of the correction electromagnet 173 supplied to the centering device 170 is obtained. The controller adjusts the extension and retraction of the tension spring 172 by changing the current value of the correction electromagnet 173 in real time to eliminate the difference between the first and second positions.

[0083] S4. After the difference between the first and second positions is eliminated, the image acquisition device 150 acquires the image between the slot 212 of the connector 210 and the plug 1622 of the rotary positioning device 160, and feeds the acquired data back to the controller of the control and power supply module 130; the controller calculates the included angle between the slot 212 and the plug 1622.

[0084] S5. According to the included angle in step S4, the controller adjusts the operation of the slip ring motor 161 of the rotary positioning device 160. The rotation of the slip ring motor 161 drives the connecting cap 162 to rotate to the position where the included angle is zero.

[0085] S6. The controller controls the locking electromagnet 140 to be energized, attracting the top of the connector 210 to the position of the connector cap 162. The plug 1622 inside the connector cap 162 is tightly connected to the socket on the top of the connector 210 to restrict the radial and circumferential movement of the connector 210.

[0086] S7. The controller controls the micro servo motor 1761 of the centering device 170 to work. The micro servo motor 1761 drives the fixing buckle 1762 to rotate towards the center of the arc, thereby fixing and locking the groove of the connector 210 and restricting the axial movement of the connector 210.

[0087] Specifically, in this embodiment, the docking device 200 gradually approaches the receiving device 100, and the docking connector 210 is inserted into or about to be inserted into the central ring of the guide connecting rod 174 of the docking slot 171. The light source 153 next to the industrial camera 152 is turned on, and the industrial camera 152 captures images of the docking connector 210 and the central ring of the guide connecting rod 174, the docking connector 210 and the connecting cap 162, and the slot 212 and plug 1622 between the connecting cap 162 and the docking connector 210. These images are transmitted to the controller. By calculating the center distance between the docking connector 210 and the guide connecting rod 174, the center distance between the docking connector 210 and the connecting cap 162, and the angle between the slot 212 and the plug 1622 between the connecting cap 162 and the docking connector 210, the center distance is decoupled to a two-dimensional coordinate system, and the first position difference and the second position difference in the two-dimensional coordinates, i.e., the x and y directions, are obtained. By substituting the formula for the balance relationship between the first position difference and the 8mm diameter electromagnet and the tension spring 172 on the connector 210, the required magnetic force can be obtained. According to the formula for the relationship between current and magnetic force, the current that needs to be supplied to the 8mm diameter electromagnet can be obtained. Adjustment is made in real time to eliminate the first position difference. Similarly, the second position difference can be eliminated using the above method.

[0088] Based on the angular relationship between the slot 212 and the plug 1622 between the connector 162 and the mating connector 210, the current of the slip ring motor 161 can be controlled to rotate the connector 162 to a position where the angle is zero, thus preparing for subsequent docking. When the position difference of the two-dimensional coordinates and the real-time angle are both zeroed under the control of the centering device 170 by the controller, the locking and fixing module starts to operate. The 52mm diameter electromagnet module provides the maximum magnetic force, attracting the head of the mating connector 210 to the position of the connector 162. The plug 1622 is tightly connected to the socket, restricting the radial and circumferential movement of the mating connector 210.

[0089] The plug 1622 is tightly connected to the socket. When the proximity switch is touched, the proximity switch outputs a contact signal to the controller. After receiving the contact signal, the controller controls the micro servo motor 1761 to work. The micro servo motor 1761 drives the fixing buckle 1762 to rotate towards the center of the arc, thereby fixing and locking the annular groove 211 on the connector 210 and restricting the axial movement of the connector 210.

[0090] When docking is required:

[0091] When the device is underwater, the docking environment is affected by poor light in the deep sea. When docking is required, the industrial camera 152 needs to be activated. The light source 153 on the industrial camera 152 is turned on, and the camera of the industrial camera 152 takes a picture and transmits the picture to the controller of the control and power supply module 130.

[0092] The main process for processing the acquired image results is as follows: dehazing → Gaussian filtering → CLAHE → Hough circle detection → contour center detection. For example... Figure 9 As shown in the figure, five sub-images are provided to illustrate the image processing process. The first sub-image is the original image. The controller first preprocesses the image, mainly by dehazing to obtain the second sub-image, which is the original grayscale image. Then, Gaussian filtering is used to remove underwater noise from the obtained image to obtain the third sub-image. Next, the CLAHE algorithm is used to enhance local contrast to obtain the fourth sub-image, highlighting the edge features of the docking hole and the joint 210. Finally, Hough circle transform is applied to the docking hole on the guide connecting rod 174 to obtain the fifth sub-image, which obtains the coordinates of the center position of the docking hole, denoted as . Similarly, using contour detection on the joint 210, the center of the member of the joint 210 is obtained, denoted as... .

[0093] Calculate the relative distance; therefore, the distance components in the X and Y axis directions are as follows:

[0094] (Horizontal deviation)

[0095] (Vertical deviation)

[0096] Then, the visual image coordinates (in pixels) are converted into actual physical coordinates using the camera's built-in parameter matrix. Let the camera focal length be f (known) and the image pixel size be s (unit: mm / pixel), then the actual physical coordinates are as follows: Z depth The distance from industrial camera 152 to guide connecting rod 174.

[0097]

[0098]

[0099] After obtaining the actual position difference, the magnitude of the current signal that the control and power supply module 130 needs to provide to the 8mm diameter electromagnet in the docking groove 171 connected to the guide connecting rod 174 is calculated. .

[0100] During the docking process, assuming the permanent magnet on the guide connecting rod 174 has a magnetic moment m1, and according to the Coulomb magnetic charge model, the magnetic moment generated by the electromagnetic coil is: let the number of coil turns be N, the current be I, and the cross-sectional area of ​​the coil be S, then the magnetic moment m = NIS (the direction is determined by the right-hand screw rule), and the magnetic moment of the fixed end, i.e., the 8mm diameter electromagnet, is m2 = NIS. At this time, the docking distance is... The magnitude of the magnetic force is:

[0101] (1);

[0102] Where μ0 is the free permeability. (Units here include meters, kilograms, seconds, and amperes);

[0103] By substituting m2 into formula (1) using the formula m=NIS, the required current for an 8mm diameter electromagnet can be calculated. :

[0104]

[0105] Based on the tension spring 172 obeying Hooke's Law F k =kΔx, which gives the equilibrium relationship between the electromagnet and the tension spring 172, as follows:

[0106] (2);

[0107] Assuming the docking is complete, the distance between the 8mm diameter electromagnet and the permanent magnet 175 inside the guide connecting rod 174 is d (known), and the positional difference between the guide connecting rod 174 and the mating joint 210 is dx = 0. However, in the initial state, only one of the four 8mm diameter electromagnets is considered. , Substituting these two terms into formula (2), we can obtain the current that the control and power supply module 130 ultimately needs to provide to the 8mm diameter electromagnet:

[0108]

[0109] Two sets of symmetrical electromagnetic coils (a total of 4 coils) are set on the X-axis (horizontal direction) and Y-axis (vertical direction). The electromagnetic coils are 8mm diameter electromagnets. Fine-tuning of the attitude is achieved through "differential control". For example:

[0110] X-axis control: When d is detected X If the current is greater than 0 (the rod is on the right side of the mating hole), then the current in the left coil (left) is increased and the current in the right coil (right) is decreased, generating a resultant force to the left, pushing the rod to the left until d... X =0.

[0111] Y-axis control: Similarly, when d Y >0 (rod above the mating hole), increase the current of the lower coil downwards and decrease the current of the upper coil upwards, generating a downward resultant force to achieve vertical alignment.

[0112] Since this can be achieved using existing technology, the description of detecting the angle between the plug 1622 on the mating cap and the socket on the mating connector 210, and transmitting the angle signal to the slip ring motor 161 to make the motor rotate to a position where the angle difference is 0° is omitted here.

[0113] When the final dx distance is zero and the angle difference is 0°, the control and power supply module 130 sends an alignment signal to the 52mm diameter electromagnet. The 52mm diameter electromagnet provides the maximum current, attracting the connector 210 to the connector cap 162 plug 1622. After the connector 210 contacts the connector cap 162, the control and power supply module 130 sends a feedback signal to the micro servo motor 1761, which rotates the fixing buckle 1762 inward to tighten the connector 210, thus achieving a complete docking.

[0114] To verify the performance of the underwater robot's precision docking mechanism and control method, this study employed MATLAB simulation experiments. Experimental scenarios were set up (covering water flow disturbances of 0.1–0.5 m / s, initial position deviations of 5–15 mm, and initial angle deviations of 0–10°), and a control group with only tension spring correction was included for reference. Figure 10 , Figure 11 The docking method described in this study achieves rapid convergence, while the control group cannot guarantee convergence. The experiment dynamically adjusts the electromagnet current, spring force, and slip ring motor speed to achieve closed-loop correction of the joint's position and angle. The performance differences between the "electromagnet-spring combined control group" and the "spring-only control group" are compared and analyzed. Simulation results show that this method can achieve rapid and accurate docking under different disturbances and deviations (time 2.1–3.8s, positioning error ≤0.8mm), and significantly improves response speed and accuracy compared to the control group (time ≥5.2s, error ≥1.8mm), verifying its robustness and efficiency in complex deep-sea environments.

[0115] The main advantages of this invention are:

[0116] 1. This invention can address the issue of inaccurate docking caused by seawater disturbance by using an image recognition and spring-magnet combined system to achieve precise fine-tuning, thereby improving docking speed and accuracy;

[0117] 2. Compared with the traditional docking device 200, it is smaller in size, which can reduce the impact of marine organism attachment or marine environmental corrosion, improve the efficiency of the recovery process, and reduce the risk;

[0118] 3. The locking mechanism utilizes a combination of a 1762 locking buckle and a magnetic attraction device to enhance the fixing strength. Furthermore, it allows both devices to rotate around an axis at any angle when necessary, improving overall mobility.

[0119] 4. It is small in size and easy to install in any location. The device is highly versatile and can be docked with underwater robots, underwater platforms, unmanned vessels, deep-sea landers, etc. The device has a relatively simple structure, is easy to install, has low cost, and is easy to maintain.

[0120] The embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A precision docking mechanism for underwater robots, comprising a receiving device (100) mounted on an underwater robot (A) and a docking device (200) mounted on an underwater robot (B), characterized in that, The docking device (200) comprises a docking head (210) and a docking fixed base (220) installed on the docking head (210), and the docking fixed base (220) is used for connecting an underwater robot (A); the receiving device (100) comprises a receiving fixed base (110) and a pressure cabin (120), the receiving fixed base (110) is used for connecting an underwater robot (B), and the receiving device (100) further comprises, in sequence, a control and power supply module (130), a locking electromagnet (140), an image acquisition device (150), a rotary positioning device (160) and a centering device (170) arranged in the pressure cabin (120), the rotary positioning device (160) and the centering device (170) are both provided with a channel for inserting the docking head (210), the image acquisition device (150) is used for collecting real-time positions of the docking head (210) and feeding back to the control and power supply module (130), the control and power supply module (130) controls the rotary positioning device (160) to adjust the rotation angle between the docking head (210) and the rotary positioning device (160), the control and power supply module (130) controls the centering device (170) to keep the docking head (210) coaxial with the rotary positioning device (160), and the control and power supply module (130) controls the locking electromagnet (140) to be powered to adsorb the docking head (210) to realize locking and fixing between the docking head (210) and the rotary positioning device (160); The rotary positioning device (160) comprises a slip ring motor (161) and a connecting cap (162). The centering device (170) comprises a docking groove (171), a tension spring (172), a correction electromagnet (173), a guide connecting rod (174) and a permanent magnet (175), the docking groove (171) is connected with a stator of the slip ring motor (161), a plurality of supports (1711) are uniformly arranged on the docking groove (171) away from the slip ring motor (161) in the circumferential direction, one correction electromagnet (173) is installed on each support (1711), the guide connecting rod (174) comprises branch rods (1741) in the same number as the supports (1711), the permanent magnet (175) is embedded in an end of the branch rod (1741) close to the support (1711), and the branch rod (1741) and the corresponding support (1711) are connected through the tension spring (172); the centering device (170) is provided with a channel for inserting the docking head (210), and the channel is located at the center of the guide connecting rod (174).

2. The precision docking mechanism for an underwater robot of claim 1, wherein, The image acquisition device (150) comprises a camera mounting rack (151), an industrial camera (152) and a light source (153), the light source (153) and the industrial camera (152) are both fixed on the camera mounting rack (151), the camera mounting rack (151) is installed in the pressure cabin (120), and the industrial camera (152) and the light source (153) are aligned with the rotary positioning device (160).

3. The precision docking mechanism for an underwater robot of claim 1, wherein, The rotor of the slip ring motor (161) is connected with the connecting cap (162) to drive the connecting cap (162) to rotate, the side wall of the slip ring motor (161) is connected with the pressure cabin (120), the connecting cap (162) is provided with a channel structure (1621) with one end open and the other end closed, and the outer contour of the channel structure (1621) is matched with the upper part of the docking head (210); and the closed end of the channel structure (1621) is made of a light-transmitting transparent material.

4. The precision docking mechanism for an underwater robot of claim 3, wherein, The closed end of the channel structure (1621) extends towards the end close to the docking head (210) and is provided with a plug (1622), and the top end of the docking head (210) is provided with a plug groove (212) matched with the plug (1622) to limit the radial and circumferential movement of the docking head (210).

5. The precision docking mechanism for an underwater robot of claim 1, wherein, The centering device (170) further comprises a second locking part (176) to limit the axial movement of the docking head (210).

6. The precision docking mechanism for an underwater robot of claim 5, wherein, The second locking part (176) comprises a plurality of micro servo steering machines (1761) and a plurality of fixed buckles (1762), the micro servo steering machines (1761) are installed at the end close to the slip ring motor (161) of the docking groove (171), the fixed buckles (1762) are connected with the micro servo steering machines (1761), the surface of the docking head (210) is provided with a ring groove (211) matched with the fixed buckles (1762) in the circumferential direction, and the micro servo steering machines (1761) drive the fixed buckles (1762) to be clamped into or away from the ring groove (211).

7. A method for precision docking control of an underwater robot, characterized in that, The precision docking mechanism applied to the underwater robot of any one of claims 1-6 comprises the following steps: S1, the docking head (210) is inserted into the guide connecting rod (174) of the centering device (170), the image acquisition device (150) acquires the image between the docking head (210) and the guide connecting rod (174) and the image between the docking head (210) and the connecting cap (162) of the rotary positioning device (160), and feeds the acquired data to the controller of the control and power supply module (130); S2, the controller calculates the center distance between the docking head (210) and the guide connecting rod (174), decouples the center distance to the two-dimensional coordinates, and obtains the first position difference value in the two-dimensional coordinates, i.e., the x and y directions; the controller calculates the center distance between the docking head (210) and the connecting cap (162), decouples the center distance to the two-dimensional coordinates, and obtains the second position difference value in the two-dimensional coordinates, i.e., the x and y directions; S3, according to the first and second position difference values in step S2 and the balance relationship formula of the electromagnet and the tension spring (172) built in the controller, the current value of the correction electromagnet (173) supplied to the centering device (170) is obtained, and the controller adjusts the extension amount of the tension spring (172) by changing the current value of the correction electromagnet (173) in real time to eliminate the first and second position difference values. S4, when the first, second position difference is eliminated, the image acquisition device (150) collects the image between the socket (212) of the adapter (210) and the plug (1622) of the rotating positioning device (160), and feeds the collected data to the controller of the control and power supply module (130); the controller calculates the included angle between the socket (212) and the plug (1622); S5, according to the included angle in step S4, the controller adjusts the work of the slip ring motor (161) of the rotating positioning device (160), and the slip ring motor (161) rotates to drive the connecting cap (162) to rotate to the position where the included angle is zero; S6, the controller controls the energization of the locking electromagnet (140), and attracts the top of the adapter (210) to the position of the connecting cap (162), so that the plug (1622) in the connecting cap (162) is closely connected with the socket at the top of the adapter (210), so as to limit the radial and circumferential movement of the adapter (210); S7, the controller controls the work of the micro servo steering engine (1761) of the centering device (170), the micro servo steering engine (1761) drives the fixed buckle (1762) to rotate to the center of the arc, realizes the fixed locking of the groove part on the adapter (210), and limits the axial movement of the adapter (210).

8. The method of claim 7, wherein, In step S3, The formula of the balance relationship of the electromagnet and the tension spring (172) is: (1); wherein μ 0 is the vacuum permeability, having a value of ; m 1 is the magnetic moment of the permanent magnet; N N is the number of turns of the electromagnetic coil; I For electromagnet current; S A is the cross-sectional area of the electromagnet coil is the approach distance; k k is the spring constant of the tension spring; the deformation amount of the tension spring under force; Docking distance formula: (2); wherein, d To correct the position distance of the permanent magnet (175) on one of the supports (1711) of the electromagnet (173) and the guide connecting rod (174). dx to correspond to a position difference of a certain support (1711) and a docking head (210); (3) ; The formula (2), (3) is brought into formula (1), and the current size formula provided by the controller to the correction electromagnet (173) is obtained: (4)。

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