Polishing device based on underwater robot and control system thereof

Abstract

The invention discloses a grinding device based on an underwater robot and a control system thereof, the device comprises a mounting connecting mechanism, a position adjusting mechanism and a grinding pollution discharge mechanism, the system comprises a sensor unit, a joint control module, and the joint control module integrates a self-adaptive control unit and a sliding mode control unit; the driving unit is integrated with a nonlinear suppression module; the self-adaptive control unit and the nonlinear suppression module are coupled to form hierarchical control, and the nonlinear suppression module compensates joint coupling disturbance torque in real time. The polishing device has the advantages that attachments on a structure can be removed and discharged through the polishing device, so that the visual field of the underwater robot is clearer, and the surface condition of the structure can be better observed; the contact force between the grinding piece and the surface of the structure is dynamically adjusted through a self-adaptive adjusting strategy and force control, excessive grinding or sliding off-target of the underwater structure grinding device is avoided, synchronous movement of all joints of the mechanical arm is achieved through a multi-joint cooperative control algorithm, and the grinding track precision is improved.

Description

Technical Field

[0001] This invention relates to the field of underwater polishing technology, specifically a polishing device and its control system based on an underwater robot. Background Technology

[0002] Currently, the underwater ultrasonic rebound combined method for testing the strength of underwater structures is one of the health assessment methods for underwater structures. This technology measures the rebound value of the structure surface by hitting it with a rebound hammer, and at the same time measures the sound velocity inside the structure by placing an ultrasonic probe close to the surface of the structure. The strength of the structure is then calculated by combining relevant formulas to assess the health status and performance of the structure.

[0003] However, the surface condition of underwater structures directly affects the accuracy of this method. Long-term exposure to the underwater environment causes the structure surface to accumulate dirt, biological shells, rust layers, and other deposits. These can prevent the rebound hammer's impact rod from directly striking the structure surface, resulting in significant deviations in the rebound value. Furthermore, they can prevent the ultrasonic probe from closely and directly adhering to the structure surface, causing the ultrasonic wave propagation path to deviate and distorting the sound velocity data. Therefore, it is essential to grind and clean the surface of underwater structures before performing ultrasonic rebound strength measurement.

[0004] However, existing methods are insufficient to solve this problem. Handheld grinding devices used by divers lack consistent grinding force and cannot operate underwater for extended periods. Small cleaning brushes can only remove soft deposits and cannot clean hard deposits such as scale, biological shells, and thick layers of rust. Larger equipment, due to its size, poor precision, and high cost, is unsuitable for complex underwater environments. Furthermore, existing underwater grinding robotic arms often employ simple PID control for joint control, which struggles to address issues like poor motion synchronization caused by joint dynamic coupling and underwater flow disturbances, resulting in low grinding trajectory accuracy and impacting subsequent inspection results. Therefore, a more efficient and reliable underwater structural grinding device is urgently needed.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this application is to at least solve one of the technical problems existing in the prior art, and to provide a grinding device and its control system based on an underwater robot. The grinding device can remove the deposits on the structure, providing a favorable surface condition for subsequent underwater ultrasonic rebound testing. At the same time, the grinding device can discharge the removed deposits, making the underwater robot's field of vision clearer, better observing the surface condition of the structure, and performing subsequent ultrasonic rebound testing. Furthermore, through an adaptive adjustment strategy, the contact force between the grinding disc and the structural surface is dynamically adjusted by force control to avoid over-grinding or slippage of the underwater structure grinding device. Through a multi-joint collaborative control algorithm, the synchronous movement of each joint of the robotic arm is achieved, improving the accuracy of the grinding trajectory.

[0007] According to a first aspect of this application, a grinding device based on an underwater robot includes a mounting and connecting mechanism, a position adjustment mechanism, and a grinding and waste removal mechanism. The mounting and connecting mechanism includes a mounting base, a robotic arm base, and a communication cable. The mounting base is bolted to an underwater robot mounting platform, and the robotic arm base is located at the top center of the mounting base. The position adjustment mechanism is hinged to the robotic arm base of the mounting and connecting mechanism via bearings, and rotates around the robotic arm base as a fulcrum. The grinding and waste removal mechanism is located at the front end of the position adjustment mechanism. A joint control module is built into the position adjustment mechanism. The joint control module includes a drive unit, a sensor unit, and a control unit. The drive unit provides power to each joint of the position adjustment mechanism, the sensor unit collects joint motion parameters, and the control unit achieves synchronous movement of each joint through a multi-joint collaborative control algorithm.

[0008] The underwater robot-based grinding device according to the embodiments of this application has at least the following beneficial effects: the arc-shaped support ring of the mounting and connecting mechanism fits onto the arc-shaped float of the underwater robot, maximizing the contact area between the two, strengthening the stability of the structure, and improving the installation adaptability; the position adjustment mechanism is fixed to the mechanical arm base of the mounting and connecting mechanism through bearing connection; the position adjustment mechanism can move the connected grinding and sewage discharge mechanism to a designated position by rotating and extending the components; at the same time, when the grinding and sewage discharge mechanism is working, the grinding and sewage discharge mechanism can change positions while grinding, without the need to control the robot movement at the same time, increasing the grinding range and improving grinding efficiency.

[0009] According to some embodiments of this application, the mounting base of the mounting connection mechanism is provided with an arc-shaped support ring, and symmetrical bolt mounting holes are provided on both sides of the arc. The mounting connection mechanism is attached to the underwater robot float through the arc-shaped support ring and is fixedly connected to the underwater robot mounting platform through the bolt mounting holes.

[0010] According to some embodiments of this application, the installation and connection mechanism further includes a robotic arm base, which is disposed at the top center of the arc-shaped support ring of the mounting base, and the communication line extends from the outer wall of the robotic arm base and connects to the underwater robot connection port.

[0011] According to some embodiments of this application, the position adjustment mechanism includes a horizontal rotating component, a zigzag connecting rod, a vertical rotating component, and a telescopic component. The horizontal rotating component is sleeved on the mechanical arm base of the mounting and connecting mechanism, and the two are connected by a bearing. The position adjustment mechanism rotates horizontally back and forth at a certain angle with the mechanical arm base as the fulcrum.

[0012] According to some embodiments of this application, the proximal end of the zigzag link is hinged to the top of the horizontal rotating component via a bearing. The zigzag link rotates back and forth in the vertical direction at a certain angle with the axis of the horizontal rotating component as the base point. The zigzag design allows the robotic arm head to reach a farther position without the need for additional joints like traditional linear links, thus reducing the cost, complexity, and control difficulty of the robotic arm.

[0013] According to some embodiments of this application, the vertical rotating component is hinged to the distal end of the zigzag connecting rod via a bearing, and the vertical rotating component rotates back and forth in the vertical direction at a certain angle with the distal end of the zigzag connecting rod as the base point. A small hydraulic drive device is installed inside the vertical rotating component.

[0014] According to some embodiments of this application, the joint control module is integrated into the position adjustment mechanism. The joint control module includes the drive unit and the sensor unit. The drive unit provides power for joint rotation, and the sensor unit includes an angular displacement sensor, a torque sensor, and an inertial measurement unit. The angular displacement sensor is installed at each joint bearing to collect the joint rotation angle and angular velocity; the torque sensor is connected in series between the reducer and the joint to collect the joint driving torque; the inertial measurement unit is installed on the top of the horizontal rotating component to collect the attitude angle, acceleration, and angular velocity information of the position adjustment mechanism.

[0015] According to some embodiments of this application, the control unit of the joint control module adopts an embedded processor. The control unit pre-stores a multi-joint coupling dynamics model and a nonlinear disturbance observer algorithm, receives joint parameters and attitude information collected by the sensor unit, and generates the desired joint trajectory by combining the coordinates of the grinding area. The target driving torque of each joint is calculated by the sliding mode cooperative control law and output to the drive unit.

[0016] Furthermore, the multi-joint coupled dynamic model considers the influence of the underwater environment, wherein...

[0017] This is the underwater viscous drag vector. Here is the viscous damping matrix. The quadratic damping matrix is ​​used to describe the relationship between underwater viscous drag and velocity; the nonlinear disturbance observer compares the observer state with known dynamic terms. Estimating interference The interference estimation error converges asymptotically.

[0018] According to some embodiments of this application, the telescopic component is installed inside the vertical rotating component, and a small hydraulic drive device is used to extend and retract the internal space of the vertical rotating component.

[0019] According to some embodiments of this application, the grinding and sewage discharge mechanism includes a brushless motor, a rotating head, and a grinding disc. The brushless motor is fixed to the end of the telescopic component, the rotating head is fixed to the brushless motor, and the grinding disc is assembled to the end of the rotating head.

[0020] According to some embodiments of this application, the brushless motor is divided into a stator assembly and a rotor assembly. The stator assembly is fixed to the end of the telescopic component, and the rotor assembly is coaxially assembled to the stator assembly. The stator assembly is wound with an electric coil, which generates a magnetic field when energized. The rotor assembly has a built-in permanent magnet and has its own fixed magnetic field. The brushless motor uses the principle of like magnetic poles repelling and unlike magnetic poles attracting to make the stator assembly rotate continuously relative to the rotor assembly.

[0021] According to some embodiments of this application, the rotating head is fixed to the brushless electronic rotor assembly, and a ring of rotating plates is designed on the side wall of the rotating head. When the rotating head rotates, the rotating plates generate water flow, which can disperse and discharge the dirt in the surrounding water a certain distance.

[0022] According to some embodiments of this application, the end of the rotating head is provided with an internal threaded hole, the grinding disc connecting shaft is equipped with an external thread, the grinding disc is screwed into the rotating head, and then the grinding disc is pressed axially by a lock nut.

[0023] According to some embodiments of this application, the mating part between the rotating head and the brushless motor is provided with anti-slip stripes. The anti-slip stripes increase the coefficient of friction when the hand or tool is operated by processing regular concave and convex patterns on the contact surface, thereby preventing slippage during the assembly and disassembly of the grinding disc.

[0024] According to some embodiments of this application, the brushless motor rotates and drives the corresponding rotating head to rotate, which in turn drives the grinding disc to rotate and grind the surface deposits of the underwater structure. When the rotating disc on the outer wall of the rotating head rotates, water flow is generated, which disperses the deposits ground off by the grinding disc, providing a good field of view for the underwater robot camera.

[0025] According to some embodiments of this application, the joint control module integrates an adaptive control unit and a sliding mode control unit, and the drive module adopts a force / position hybrid control strategy. It compensates for joint coupling interference torque in real time through a nonlinear interference observer, effectively solving the problems of joint coupling and water flow disturbance in the underwater environment, and improving the grinding trajectory accuracy and grinding efficiency.

[0026] Specifically, this method designs a hybrid control module integrating adaptive control and sliding mode control at the end of the grinding device, and achieves high-precision and robust grinding task execution based on a force / position hybrid control strategy.

[0027] A polishing method based on an underwater robot-based polishing apparatus according to a second aspect embodiment of this application includes the following steps: The polishing device is mounted on an underwater robot. The underwater robot moves to the ultrasonic rebound detection area, observes the surface condition of the structure through a camera, and moves to the position where polishing is required. The joint control module is activated, the sensor unit collects the initial motion parameters and posture information of each joint, and the control unit establishes a multi-joint coupled dynamic model to generate the desired joint trajectory. The control unit estimates the joint coupling interference and hydrodynamic disturbance through the interference observer of the nonlinear suppression module, and outputs the sliding mode cooperative control law. The drive unit controls the position and adjusts the movement of each joint of the mechanism according to the control law, so that the grinding disc abuts against the part to be ground. When the grinding and sludge removal mechanism is activated, the grinding disc rotates to begin grinding the deposits on the surface of the underwater structure, removing the deposits. The rotating head then disperses the deposits that have been ground off by the grinding disc. During the polishing process, the joint control module collects joint motion parameters in real time and dynamically corrects the control law to ensure that the polishing disc moves along the desired trajectory and completes the polishing work.

[0028] The advantages of this invention compared to existing technologies are: This invention employs the underwater structure grinding device of the first embodiment of this application. The arc-shaped support ring of the mounting and connecting mechanism can fit snugly against the arc-shaped float of the underwater robot, thereby maximizing the contact area between the two and enhancing structural stability and installation adaptability. The position adjustment mechanism is connected to the robotic arm base of the mounting and connecting mechanism via bearings. Through the rotation and extension of the components, it can not only move the connected grinding and sewage discharge mechanism to a designated position, but also allow the grinding and sewage discharge mechanism to change position synchronously during the grinding process without controlling the robot's movement, thus expanding the grinding range and improving grinding efficiency. The built-in sliding mode control module is responsible for global robust tracking. The multi-joint collaborative algorithm of the sliding mode control module, combined with the parameter fine-tuning update control output provided by the adaptive framework, is coupled with the nonlinear disturbance observer (NDO) to form hierarchical control, achieving fast convergence and disturbance resistance, effectively solving the problems of joint coupling and water flow disturbance in the underwater environment, and improving the grinding trajectory accuracy. The nonlinear suppression module's broken-line rod coupling compensation mechanism uses a dedicated broken-line rod coupling observer. When the broken-line rod is deployed, the coupling interference torque between adjacent joints can be reduced by the observer compensation. Through a layered force / position hybrid strategy, it ensures constant contact force of the grinding disc, adapts to irregular surfaces, solves the problem of contact force fluctuation under hybrid control in underwater operations, improves grinding efficiency, and reduces coupling interference, which is an improvement over traditional PID control. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a grinding device based on an underwater robot, according to an embodiment of this application.

[0030] Figure 2 This is an exploded view of a grinding device based on an underwater robot, according to an embodiment of this application.

[0031] Figure 3 This is a schematic diagram of the installation and connection mechanism in the grinding device based on an underwater robot according to an embodiment of this application.

[0032] Figure 4 This is a schematic diagram of the position adjustment mechanism in the grinding device based on an underwater robot according to an embodiment of this application.

[0033] Figure 5 This is a schematic diagram of the grinding and sewage discharge mechanism in the grinding device based on an underwater robot according to an embodiment of this application.

[0034] Figure 6 This is a schematic diagram of the control method of the grinding device based on an underwater robot in an embodiment of this application.

[0035] Reference numerals: 100, mounting connection mechanism; 101, mounting base; 102, robotic arm base; 103, communication cable; 104, mounting hole; 105, support ring; 200. Position adjustment mechanism; 201. Horizontal rotating component; 202. Zigzag connecting rod; 203. Vertical rotating component; 204. Telescopic component; 205. Expansion compartment; 206. Top hinge end; 207. Proximal hinge interface of connecting rod; 208. Distal hinge interface of connecting rod; 209. Vertical hinge end; 300. Grinding and sewage discharge structure; 301. Brushless motor; 302. Rotary head; 303. Grinding disc; 304. Guide vane; 305. Anti-slip texture; 306. Stator assembly; 307. Rotor assembly. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. Identical components are indicated by the same reference numerals.

[0037] It should be noted that the terms “front,” “back,” “left,” “right,” “up,” and “down” used in the following description refer to the directions shown in the attached diagram, while the terms “inside” and “outside” refer to the directions toward or away from the geometric center of a specific component, respectively.

[0038] To make the content of this invention easier to understand, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings.

[0039] like Figure 1 As shown in the illustration, this application provides a grinding device based on an underwater robot. The underwater structure grinding device includes a mounting and connecting mechanism 100, a position adjustment mechanism 200, and a grinding and waste removal mechanism 300. The mounting and connecting mechanism 100 is fixed to the underwater robot via bolts. The position adjustment mechanism 200 is connected and fixed to the robotic arm base 102 of the mounting and connecting mechanism 100 via bearings. Through the rotation and extension of the components, the grinding and waste removal mechanism 300 can be moved to a designated position, and its position can be switched synchronously during grinding without requiring robot movement, thereby expanding the grinding range and improving grinding efficiency. The grinding and waste removal mechanism 300 uses a brushless motor 301 to provide rotational power, which in turn provides grinding power to the grinding discs 303, grinding off the deposits on the structural surface. The guide vanes 304 rotating on the outer wall of the rotating head 302 generate water flow to disperse and discharge the deposits ground off by the grinding discs, completing the grinding of the underwater structural surface.

[0040] In some examples, the mounting base 101 of the mounting connection mechanism 100 is provided with an arc-shaped support ring 105, and the support ring 105 has symmetrically distributed bolt mounting holes 104 on both sides; with the help of the arc-shaped support ring 105, the mounting connection mechanism 100 can fit with the underwater robot float, and then be fixedly connected to the underwater robot mounting platform by bolts passing through the bolt mounting holes 104.

[0041] The installation and connection mechanism 100 also includes a robotic arm base 102, which is located at the top center of the arc-shaped support ring 105 of the mounting base 101. The robotic arm base 102 is equipped with integrated cables inside. Furthermore, the communication line 103 extends from the outer wall of the robotic arm base and connects to the dock of the underwater robot. The outer layer of the line is wrapped with a high-voltage resistant and corrosion-resistant polytetrafluoroethylene protective sleeve, which can stably protect the internal signal transmission cable in the complex underwater environment. In some examples, the position adjustment mechanism 200 includes a horizontal rotating component 201, a zigzag connecting rod 202, a vertical rotating component 203, and a telescopic component 204. The position adjustment mechanism 200 is sleeved on the robotic arm base 102 of the mounting connection mechanism 100 through the internal annular structure of the horizontal rotating component 201. The two are connected by a bearing. Through this connection structure, the position adjustment mechanism can rotate back and forth in the horizontal direction around the robotic arm base as the center. The horizontal rotating component 201 has an outwardly protruding expansion chamber 205 on its outer wall, which increases the internal space and provides sufficient space for cable arrangement, avoiding cable tangling and jamming. Furthermore, the proximal hinge interface 20207 of the broken line type connecting rod 202 is hinged to the top hinge end 206 of the horizontal rotating component 201 through a bearing. The broken line type connecting rod 202 rotates back and forth in the vertical direction with the top hinge end 206 of the horizontal rotating component 201 as the base point. Understandably, compared to traditional linear linkages, the special design of the zigzag linkage 202 can optimize the lever arm transmission path, allowing the robotic arm head to extend to a more distant working position without increasing the arm length. At the same time, without the need for additional joint components, it not only reduces the number of core components such as joint drive motors and reducers, directly reducing the manufacturing and maintenance costs of the robotic arm, but also simplifies the overall mechanical structure, avoids the error accumulation problem that may occur when multiple joints are coordinated, and significantly reduces the programming difficulty and operational stability risk of the control system. It is especially suitable for scenarios with limited space but a wide working range requirement. In some examples, the hinge end 209 of the vertical rotating component 203 is hinged to the distal hinge interface 208 of the broken line connecting rod 202 via a bearing. The vertical rotating component 203 uses the distal hinge interface 208 of the broken line connecting rod 200 as a fixed base point to smoothly complete the reciprocating rotation in the vertical direction within a preset angle range.

[0042] The vertical rotating component 203 has a small hydraulic drive device installed in its internal compartment. The telescopic component 204 is mounted on the hydraulic drive device and performs axial telescopic movement with the internal compartment of the vertical rotating component 203 as the telescopic movement path. It is understandable that the telescopic component 204 plays a crucial role. Without the telescopic component 204, the grinding device relies on the rotation of the horizontal rotating component 201 and can only perform grinding operations along a circular trajectory. However, with the addition of the telescopic component 204, the axial telescopic movement of the telescopic component 204, in conjunction with the coordinated action of the original joints of the robotic arm, allows the movement trajectory of the end-grinding and waste removal mechanism 300 to be expanded into straight lines and curves, effectively improving the adaptability and operational capability of the grinding device under different grinding conditions. In some examples, the grinding and sewage discharge mechanism 300 includes a brushless motor 301, a rotating head 302, and a grinding disc 303. The brushless motor 301 consists of a stator assembly 306 and a rotor assembly 307. The stator assembly 306 of the brushless motor 301 is rigidly connected to the head of the telescopic component 204 via a flange structure. Furthermore, the rotor assembly 307 of the brushless motor 301 is coaxially nested on the outside of the stator assembly 306, forming a radial clearance fit. A three-phase armature coil is wound on the silicon steel core of the stator assembly 306, generating a rotating magnetic field when energized; high-performance permanent magnets are embedded in the yoke of the rotor assembly 307, forming a stable inherent magnetic field. The brushless motor 301 controls the current direction of the stator coils through an electronic commutation device, utilizing the electromagnetic force of like poles repelling and unlike poles attracting to drive the rotor assembly 307 to rotate continuously relative to the stator assembly 306, thereby achieving efficient conversion of electrical energy to mechanical energy and providing stable power output for the grinding and sewage discharge mechanism 300. The electromagnetic component of the stator assembly 306 in the brushless motor 301 is potted for waterproofing. The stator assembly 306 core, winding coils, and lead interfaces are all potted with polyurethane or epoxy resin potting compound, which cures to form a sealing layer. This layer tightly covers the electromagnetic components, preventing moisture intrusion and also provides insulation and auxiliary heat dissipation, ensuring stable operation of the motor in underwater or humid environments. Furthermore, the rotating head 302 is coaxially mounted on the output end of the rotor assembly 307 of the brushless motor 301. A ring of guide vanes 304 with a turbine-shaped surface design is arranged along the circumferential direction on the side wall of the rotating head 302. The curvature and tilt angle of the vanes are designed with reference to the principles of fluid dynamics. Understandably, when the rotating head 302 rotates at high speed under the drive of the rotor assembly 307, the turbofan-type guide vane 304 cuts the water to form a strong convection field, which can not only efficiently disperse the suspended matter generated by grinding in the surrounding water, but also use the pushing force of the water flow to discharge it to a certain distance outside the working area, so as to avoid the accumulation of pollutants and suspended matter affecting the grinding accuracy and the equipment operating environment. In some examples, the grinding disc 303 is fitted with the internal threaded hole at the front end of the rotating head via a connecting shaft with external threads. After being inserted, it is axially tightened with a lock nut. Disassembly is performed by reversing the operation, which allows for quick removal, achieving stable and convenient assembly and disassembly of the grinding disc. Furthermore, anti-slip stripes 305 are provided between the rotating head 302 and the brushless motor 301. The raised and recessed texture increases friction, making the grinding disc 303 more stable to hold when being installed and removed, preventing slippage, facilitating quick replacement, ensuring continuous operation and convenient maintenance; In some examples, the control system built into the underwater robot-based grinding device executes steps such as... Figure 6 As shown: S1: After installing the grinding device onto the underwater robot mounting platform and connecting the communication line to the underwater robot connection port, manipulate the underwater robot to reach the bridge pier position that needs to be ground, input the desired trajectory d, collect the actual position q of the grinding device, and calculate the error e. S2: The joint control module starts, the sensor unit collects the initial parameters and posture information of each joint, the control unit calls the adaptive control unit and the sliding mode control unit; the drive unit outputs the drive torque according to the sliding mode control law, and the control position adjustment mechanism drives the grinding and sewage discharge mechanism to move to the surface of the pier, and the grinding disc contacts the surface of the pier. S3: The joint control module estimates the total disturbance using the Nonlinear Observer (NDO). ,

[0043] in, This is the observation gain matrix based on the Hurwitz stabilization design.

[0044] S4: Grinding device drive module receiving error Then, extract the total disturbance. Error signal, construct sliding surface s, the sliding surface is:

[0045] in, , The coefficients of the integral term are updated and adjusted through a nonlinear adaptive module to suppress chattering.

[0046] S5: The sliding mode control unit is equipped with a multi-joint cooperative control algorithm, the multi-joint cooperative control algorithm This includes establishing a multi-joint coupled dynamic model, designing a sliding mode cooperative control law, and updating the output:

[0047] S6: The joint control module calls the adaptive module to collect the contact force at the end of the grinding and sewage discharge mechanism in real time, including the normal force and position. and speed Water flow velocity is estimated using an external water flow sensor. The adaptive module updates the model through online parameter estimation, adjusting the contact force between the grinding disc and the structure surface to prevent over-grinding or slippage of the underwater structure grinding device. The updated output is as follows: , in Based on fuzzy logic rules, Dynamic adjustment of water flow intensity; For the position sub-control of the force / position hybrid control law in the adaptive unit, the PD adaptive form is adopted:

[0048] For force control of the force / position hybrid control law in the adaptive unit, impedance control is adopted:

[0049] S7: Output via multi-joint coupled dynamics model The output of the adaptive unit It integrates equivalent control, switching control, and fuzzy compensation to generate control signals. , The output update strategy primarily employs an adaptive control framework based on adaptive units. It utilizes a multi-joint cooperative control algorithm, combined with a radial basis function neural network, to perform online parameter estimation and compensation. The online parameter estimation model update form is as follows:

[0050] in, The weight matrix is ​​updated based on Lyapunov stability; S8: Output via nonlinear suppression module The output of the adaptive unit The coupling forms a layered control, suppresses vibration, and outputs a smooth control signal to drive the grinding device. S9: The grinding device performs the grinding task and provides real-time feedback of position q to form a closed-loop control.

[0051] In some examples, the position adjustment mechanism 200 has a built-in control drive module, and the mounting connection mechanism, the position adjustment mechanism 200, and the grinding and sewage discharge mechanism 300 are equipped with integrated cables. The device is powered and controlled by the cables.

[0052] This application also provides an underwater robot, including a robot body and a grinding device as described in the above embodiments. The robot body and the grinding device are detachably connected. The robot body is provided with a mounting platform that cooperates with the mounting connection mechanism 100 so that the grinding device can be securely mounted on the underwater robot body.

[0053] This application also provides a polishing method using the underwater robot described in the above embodiments, comprising the following steps: During the preparation phase, when the underwater robot reaches the bridge pier that needs to be polished, it activates the position adjustment mechanism to adjust the polishing and sewage discharge mechanism to the surface of the bridge pier, and the polishing disc contacts the surface of the bridge pier. During the grinding stage, the grinding and sewage discharge mechanism is activated. The entire grinding and sewage discharge mechanism rotates clockwise, and the grinding discs begin to grind the surface of the bridge pier. When the guide vanes on the outer wall of the rotating head rotate, water flow is generated, which disperses and discharges the deposits that are ground off by the grinding discs. At the same time, the position adjustment mechanism drives the grinding and sewage discharge mechanism to grind along a predetermined trajectory.

[0054] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A control system for a grinding device based on an underwater robot, characterized in that: include; The sensor unit includes an angular displacement sensor, a torque sensor, and an inertial measurement unit. The angular displacement sensor collects the rotation angle of each joint, the torque sensor collects the joint driving torque, and the inertial measurement unit collects the attitude information of the position adjustment mechanism. The joint control module integrates an adaptive control unit and a sliding mode control unit; The drive unit integrates a nonlinear suppression module and adopts a force / position hybrid control strategy, estimating the total disturbance online through a disturbance observer; The adaptive control unit is coupled with the nonlinear suppression module to form a hierarchical control, which suppresses chattering and outputs a smooth control signal. The drive grinding device performs the grinding task and provides real-time position feedback. This forms a closed-loop control, and the nonlinear suppression module compensates for joint coupling interference torque in real time.

2. The control system for a grinding device based on an underwater robot according to claim 1, characterized in that, The adaptive control unit collects the contact force at the end of the grinding device in real time through force and torque sensors and position sensors, including normal force and tangential force, and position. and speed Water flow velocity is estimated using an external water flow sensor. The adaptive control unit is equipped with an adaptive control framework designed to address the dynamic uncertainties, hydrodynamic parameter variations, and differences in the hardness of deposits in the grinding and wastewater discharge mechanism. This adaptive control framework, combined with a radial basis function neural network, performs online parameter estimation and compensation to ensure end-point trajectory accuracy. Force control dynamically adjusts the contact force between the grinding disc and the structural surface, preventing over-grinding or slippage of the underwater structure grinding device. The online parameter estimation model update format is as follows: ， The input to the adaptive control framework is a state vector. The output is the estimated disturbance. The weight update law is based on Lyapunov stability, where, This is the weight matrix. For learning rate, For radial basis functions, To track errors, It is a positive definite solution of the Lyapunov matrix.

3. The control system for a grinding device based on an underwater robot according to claim 1, characterized in that: The nonlinear suppression module integrated in the drive unit adopts a force / position hybrid adaptive strategy. The force / position hybrid adaptive strategy equations include position sub-control and force sub-control, and the equations are established as follows: Position sub-control adopts PD adaptive form: ， Force control adopts impedance control: ， in, For Jacobian matrices, , , The desired impedance parameter is adaptively adjusted to suit the hardness of the deposit, and the hybrid control output is used. ,in Based on fuzzy logic rules, Dynamic adjustment of water flow intensity; The nonlinear suppression module includes a disturbance observer (NDO) for estimating the total disturbance. The nonlinear suppression module includes a broken-line linkage coupling compensation mechanism. Using a dedicated broken-line linkage coupling observer, when the broken-line linkage of the position adjustment mechanism is deployed, the coupling interference torque between adjacent joints can be reduced by the observer compensation. Through a layered force / position hybrid strategy, when the linkage deployment angle is greater than 45°, the torque of adjacent joints is observed and compensated to ensure a constant contact force of the grinding disc, adapt to irregular surfaces, solve the problem of contact force fluctuation under hybrid control in underwater operations, and improve grinding efficiency.

4. The control system of the grinding device based on an underwater robot according to claim 1, characterized in that: The sliding mode control unit is equipped with a multi-joint collaborative control module, which includes establishing a multi-joint coupled dynamics model: ， in The joint angle vector. For the angle of the horizontally rotating component, angle of the broken-line type connecting rod joint. For the angle of the vertically rotating component, The inertia matrix, For the centrifugal force matrix, The resultant force vector of gravity and buoyancy. This is the underwater viscous drag vector. This is the joint driving torque vector. For unknown disturbances affected by joint coupling and attachment resistance; The multi-joint collaborative control module includes the design of a sliding mode collaborative control law: ， in, To generate the desired joint angle based on the grinding area information provided by the underwater robot, To track errors, For sliding surface, For joint coupling disturbances and hydrodynamic disturbances estimated by a nonlinear disturbance observer, , It is a positive definite diagonal matrix. It is a symbolic function.

5. A grinding device based on an underwater robot, employing the control system described in any one of claims 1-4, characterized in that, include: The mounting connection mechanism (100) includes a mounting base (101) and a communication line (103). The mounting base (101) is used to fix the underwater robot mounting platform. A robotic arm base (102) is fixedly installed at the center of the mounting base (101). The communication line (103) is connected to the underwater robot connection port. The mounting base (101) includes an arc-shaped support ring (105). Several bolt mounting holes (104) are opened on both sides of the mounting base. A position adjustment mechanism (200) includes a horizontal rotating component (201), which is hinged to the upper end of the robotic arm base (102) via a bearing. A zigzag connecting rod (202) is hinged to the upper end of the horizontal rotating component (201) via a bearing. A vertical rotating component (203) is hinged to the distal joint of the zigzag connecting rod (202) via a bearing. A telescopic component (204) is assembled inside the vertical rotating component (203). The telescopic component (204) is telescopically extended or retracted by a driver inside the vertical rotating component (203). The grinding and sewage discharge mechanism (300) includes a brushless motor (301), a rotating head (302), and a grinding disc (303). The brushless motor (301) includes a stator assembly (306) and a rotor assembly (307). The stator assembly (306) is fixed to the end of the telescopic component (204), and the rotor assembly (307) is coaxially assembled to the stator assembly (306). The outer wall of the rotating head (302) is provided with a vortex-shaped guide vane (304) along the circumferential direction. The guide vane (304) rotates to drive the formation of water flow.

6. A grinding device based on an underwater robot according to claim 5, characterized in that, The arc-shaped support ring (105) is designed with an arc shape according to the size of the arc-shaped float of the underwater robot. The arc-shaped support ring (105) is attached to the float of the underwater robot. The grinding device is bolted to the underwater robot mounting platform through the bolt mounting hole (104). The communication line (103) extends from the outer wall of the robotic arm base (102) and connects to the underwater robot connection port.

7. A grinding device based on an underwater robot according to claim 5, characterized in that, The rotating head (303) is coaxially fixed to the output end of the rotor assembly (307). The rotor assembly (307) rotates around the stator assembly (306) through electromagnetic induction and drives the rotating head (302) to rotate synchronously. The grinding disc (304) is assembled at the end of the rotating head (302). The grinding disc (304) is detachable and replaceable.

8. A method of using a polishing device based on an underwater robot, employing the polishing device and its control system as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Install the grinding device onto the underwater robot mounting platform and connect the communication line (103) to the underwater robot connection port, and control the underwater robot to reach the bridge pier that needs to be ground; Step 2: The joint control module starts up, the sensor unit collects the initial parameters and posture information of each joint, and the control unit calls the multi-joint collaborative control algorithm; Step 3: The drive unit outputs drive torque according to the control law, controls the position adjustment mechanism to drive the grinding and sewage discharge mechanism to move to the surface of the pier, and the grinding disc (303) contacts the surface of the pier. Step 4: Start the grinding and cleaning mechanism to remove dirt. During the grinding process, the joint control module collects joint motion parameters in real time and dynamically corrects the control law to ensure the accuracy of the grinding trajectory.

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