Composite sea urchin catching robot and sea urchin catching method

Abstract

The invention discloses a combined type sea urchin catching robot and a sea urchin catching method, the combined type sea urchin catching robot comprises a robot moving chassis, the robot moving chassis comprises a robot frame body, a propelling system, floating systems and moving systems, the moving systems are symmetrically installed on the two sides of the bottom of the robot frame body, and the floating systems are symmetrically installed on the top of the robot frame body; the sealed cabin is mounted on the robot frame body; the mechanical arm device comprises a multi-degree-of-freedom mechanical arm and a mechanical claw, the multi-degree-of-freedom mechanical arm is fixed to the top of the front end of the robot frame body through a mechanical arm base, and the mechanical claw is installed at the front end of the multi-degree-of-freedom mechanical arm through a wrist joint double-shaft steering engine; the visual communication system is mounted at the top of the front end of the sealed cabin; and the control device is mounted in the sealed cabin. The method can quickly identify the area where the sea urchins are located and automatically go to the sea urchin dense area, the fatigue degree of personnel is reduced, and the specific fishing efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of marine product harvesting technology, and in particular to a composite sea urchin harvesting robot and a sea urchin harvesting method. Background Technology

[0002] Sea urchins, a marine organism with high economic value, have traditionally been harvested using manual diving. However, this method has many drawbacks, such as low efficiency, high labor intensity, and threats to the lives of divers. Furthermore, it is ill-suited to the complex and ever-changing underwater environment. With the continuous advancement of underwater robotics technology, using robots for sea urchin harvesting is gradually becoming a new trend.

[0003] However, most underwater harvesting robots currently on the market are designed for fish or other seafood, and their specific needs for sea urchin harvesting are not yet fully met. Therefore, developing an underwater robot and new harvesting technology specifically for sea urchin harvesting is of great significance for improving sea urchin harvesting efficiency, ensuring the safety of divers, and protecting the marine ecological environment. Summary of the Invention

[0004] The purpose of this invention is to provide a composite sea urchin harvesting robot and sea urchin harvesting method to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following solution: The present invention provides a composite sea urchin harvesting robot, comprising:

[0006] A robot mobile chassis includes a robot frame, a propulsion system, a floating system, and a moving system. The moving system is symmetrically installed on both sides of the bottom of the robot frame, the floating system is symmetrically installed on the top of the robot frame, and the propulsion system is installed between the moving system and the floating system.

[0007] A sealed chamber, which is mounted on the robot frame;

[0008] A robotic arm device, comprising a multi-degree-of-freedom robotic arm and a robotic gripper, wherein the multi-degree-of-freedom robotic arm is fixed to the top of the front end of the robot frame via a robotic arm base, and the robotic gripper is mounted on the front end of the multi-degree-of-freedom robotic arm via a wrist joint dual-axis servo motor;

[0009] A visual communication system, which is installed on top of the front end of the sealed chamber;

[0010] A control device is installed inside the sealed chamber.

[0011] According to the composite sea urchin harvesting robot provided by the present invention, the propulsion system includes six underwater thrusters, two of which are vertical thrusters and four are horizontal thrusters; the vertical thrusters are installed on both sides of the center line of the robot frame in a dual-axis symmetrical layout, with the positive output port pointing vertically downward; the horizontal thrusters are arranged in a spatial array at a 45° tilt angle, fixedly installed at the four diagonal gaps of the robot frame, and connected to the control device in the sealed chamber through waterproof cables.

[0012] According to the composite sea urchin harvesting robot provided by the present invention, the floating system includes foam floats, which are symmetrically fixed to the upper fixing plate on the top of the robot frame by screws, for adjusting the buoyancy balance of the robot.

[0013] According to the composite sea urchin harvesting robot provided by the present invention, the mobile system includes four track groups and a motor housing; the track groups are symmetrically installed at the four corners of the bottom of the robot frame; the motor housing adopts a closed waterproof structure, is installed on the robot frame, and is connected to the drive wheel of the track group through the end drive shaft to provide power to the track group.

[0014] According to the composite sea urchin harvesting robot provided by the present invention, the sealed chamber includes an acrylic tube body, a hemispherical cover, a silicone pad, an O-ring, and a sealing cap; the front end of the acrylic tube is fixedly connected to the sealing cap, and the hemispherical cover and the silicone pad are fixed to the sealing cap by bolts; a wire threading screw ring is provided at the end of the acrylic tube for the cable to pass through and to prevent seawater from entering, and the acrylic tube body is fixed between the upper fixing plate by an upper fixing frame and a lower fixing frame.

[0015] According to the composite sea urchin harvesting robot provided by the present invention, the multi-degree-of-freedom robotic arm includes a shoulder joint system, an upper arm system, and a forearm system;

[0016] The shoulder joint system includes a robotic arm base, a servo motor mounting base, a single-axis servo motor for the shoulder joint, a dual-axis servo motor for the shoulder joint, and a shoulder joint U-shaped bracket. The robotic arm base is fixedly connected to an upper fixed plate. The servo motor mounting base is connected to the robotic arm base via bearings and is fixedly connected to the single-axis servo motor for the shoulder joint. The output shaft of the single-axis servo motor for the shoulder joint is connected to the robotic arm base. The dual-axis servo motor for the shoulder joint is fixed to the shoulder joint U-shaped bracket.

[0017] The boom system includes an inner boom link, an outer boom link, a dual-axis servo motor for the elbow joint, and a U-shaped bracket for the elbow joint; wherein, the inner boom link is connected by a copper column, the outer boom link is connected to the inner boom link by a copper column, and the output shaft of the dual-axis servo motor for the elbow joint is connected to the U-shaped bracket for the elbow joint.

[0018] The forearm system includes an inner forearm link, an outer forearm link, a dual-axis servo motor of the wrist joint, a single-axis servo motor of the wrist joint, and a U-shaped support of the wrist joint; wherein, the outer forearm link and the inner forearm link are connected by a copper column, the dual-axis servo motor of the wrist joint is fixed to the inner forearm link and connected to the U-shaped support of the wrist joint, and the output shaft of the single-axis servo motor of the wrist joint is fixedly connected to the U-shaped support of the wrist joint.

[0019] The shoulder joint dual-axis servo, shoulder joint single-axis servo, elbow joint dual-axis servo, wrist joint dual-axis servo, and wrist joint single-axis servo are all waterproof servos.

[0020] According to the composite sea urchin harvesting robot provided by the present invention, the mechanical claw includes an upper gripper, a lower gripper, a gripper fixing component, and a gripper drive servo motor; wherein, the gripper fixing component is connected to a single-axis servo motor of the wrist joint via a multi-functional bracket, the gripper drive servo motor is fixed to the gripper fixing component and its output shaft is connected to the upper gripper, and the lower gripper is fixedly connected to the gripper fixing component; the upper gripper and the lower gripper adopt a flexible mesh folding structure and are arranged in a crescent shape.

[0021] According to the composite sea urchin harvesting robot provided by the present invention, the visual communication system includes a wide-angle underwater camera and a rigid camera bracket, one end of which is connected to the O-ring bolt on the upper part of the sealed chamber. The wide-angle underwater camera is mounted on the rigid camera bracket via a flange, and the wide-angle underwater camera is connected to the image transmission module built into the sealed chamber via a waterproof cable.

[0022] A method for harvesting sea urchins includes the following steps:

[0023] Step 1: Multimodal descent and real-time obstacle avoidance. The control device drives the vertical thruster and foam float to adjust the descent speed in coordination. At the same time, the horizontal thruster is activated to perform lateral displacement. The distance to obstacles is monitored in real time based on the laser ranging module. When the distance to the obstacle is <10mm, the obstacle avoidance path is generated through the PID control algorithm. After saving the current movement pulse count, the track group is controlled to move horizontally to avoid the obstacle. Finally, the remaining pulse count is calculated to accurately reach the target point.

[0024] Step 2, sea urchin identification and autonomous localization: After the robot touches the bottom, the visual communication system collects seabed images, the control device executes the MSW-YOLOv8 recognition algorithm, outputs the coordinates of the dense sea urchin area and drives the track group to move to the target area.

[0025] Step 3, adaptive non-destructive harvesting: When the sea urchin enters the working range of the robotic arm, a six-degree-of-freedom robotic arm grasping trajectory is generated based on binocular vision data and inverse kinematics algorithm. The mesh robotic claw is driven to perform clamping with closed-loop force control, and the sea urchin is transferred to the collection chamber and the chamber cover is closed.

[0026] Step four, dynamic decision-making and stable return: monitor the capacity of the collection bin in real time. If it is not full, return to the new working area in step two. If it is full, start the propulsion system to float up, and use the gyroscope to monitor the attitude angle and the PID controller to adjust the propulsion output to maintain navigation stability until it floats up.

[0027] The present invention discloses the following technical effects:

[0028] This invention integrates a propulsion system, a floating system, and a mobility system into a mobile chassis. It can propel itself flexibly in water and move stably on the seabed. At the same time, it can adapt to different water depths and terrains (such as rocky reefs and sandy beds) through buoyancy adjustment, thus solving the problem that a single mobility method is difficult to cope with complex marine environments.

[0029] The multi-degree-of-freedom robotic arm of this invention expands the working radius. Combined with the angle adjustment capability of the wrist joint dual-axis servo motor, the robotic claw can adapt to various angle scenarios where sea urchins attach (such as tilted rocks and crevices), achieving precise grasping with "large-area coverage + small-angle fine adjustment", reducing the probability of missed or mis-grabbing.

[0030] The visual communication system of this invention provides real-time environmental feedback, and the control device integrates information and automatically plans the path, reducing human intervention and improving fishing efficiency; compared with traditional manual diving fishing, it can reduce labor costs and operational risks.

[0031] The waterproof sealing design of the sealed chamber for the control device in this invention ensures the long-term stable operation of the core control components underwater; the modular installation of each system facilitates maintenance and upgrades, extending the service life of the equipment.

[0032] The precise visual positioning and mechanical claw control of this invention can reduce the accidental capture of non-target marine organisms, reduce the disturbance to the marine ecological environment, and conform to the concept of sustainable fishing. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a front view of the composite sea urchin harvesting robot of the present invention;

[0035] Figure 2 This is a rear view of the composite sea urchin harvesting robot of the present invention.

[0036] Figure 3 This is a top view of the composite sea urchin harvesting robot of the present invention;

[0037] Figure 4 This is a schematic diagram of the sealed chamber structure of the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of the robotic arm device of the present invention;

[0039] Figure 6 This is a flowchart of the sea urchin harvesting method of the present invention;

[0040] Figure 7 A flowchart for multi-angle joint three-dimensional movement;

[0041] Figure 8 This is a schematic diagram of the control principle of the robotic arm device.

[0042] Figure 9 Here is a flowchart of the PID control algorithm;

[0043] Figure 10 Diagram of the yaw attitude angle motion control system;

[0044] Figure 11 This is a schematic diagram of the roll attitude angle motion control principle.

[0045] Figure 12 Here is a diagram of the depth controller structure;

[0046] Figure 13 Here is the flowchart for attitude angle control;

[0047] Figure 14 This is a flowchart for deep control.

[0048] The components include: 1. Robot mobile chassis; 2. Sealed cabin; 3. Robotic arm device.

[0049] 101. Propeller; 102. Foam float; 103. Track assembly;

[0050] 201. Acrylic tube body; 202. Hemispherical cover; 203. Silicone gasket; 204. O-ring; 205. Sealing cap;

[0051] 301. Robotic arm base; 302. Servo mount; 303. Shoulder joint single-axis servo; 304. Shoulder joint dual-axis servo; 305. Shoulder joint U-shaped bracket; 306. Upper mounting plate; 307. Upper arm inner link; 308. Upper arm outer link; 309. Elbow joint dual-axis servo; 310. Elbow joint U-shaped bracket; 311. Forearm inner link; 312. Forearm outer link; 313. Wrist joint dual-axis servo; 314. Wrist joint single-axis servo; 315. Wrist joint U-shaped bracket; 316. Upper gripper; 317. Lower gripper; 318. Gripper fixing component; 319. Gripper drive servo. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] Reference Figures 1-5 This invention provides a composite sea urchin harvesting robot, comprising:

[0055] The robot mobile chassis 1 includes a robot frame, a propulsion system, a floating system, and a moving system. The moving system is symmetrically installed on both sides of the bottom of the robot frame, the floating system is symmetrically installed on the top of the robot frame, and the propulsion system is installed between the moving system and the floating system.

[0056] Sealed compartment 2 is mounted on the robot frame;

[0057] The robotic arm device 3 includes a multi-degree-of-freedom robotic arm and a robotic gripper. The multi-degree-of-freedom robotic arm is fixed to the top of the front end of the robot frame via a robotic arm base 301, and the robotic gripper is mounted on the front end of the multi-degree-of-freedom robotic arm via a wrist joint dual-axis servo motor 313.

[0058] A visual communication system is installed on top of the front end of the sealed chamber 2;

[0059] The control device is installed inside the sealed chamber 2.

[0060] The design was further optimized, and the propulsion system includes six underwater thrusters 101, two of which are vertical thrusters 101 and four are horizontal thrusters 101. The vertical thrusters 101 are installed on both sides of the center line of the robot frame in a dual-axis symmetrical layout, with the positive output port pointing vertically downward. The horizontal thrusters 101 are arranged in a spatial array at a 45° tilt angle, fixedly installed in the four diagonal gaps of the robot frame, and connected to the control device in the sealed chamber 2 through waterproof cables.

[0061] The system employs six underwater thrusters 101 (2 vertical and 4 horizontal). The vertical thrusters 101 are arranged in a dual-axis symmetrical layout to provide lifting power, while the horizontal thrusters 101 are spatially arrayed at a 45° tilt angle. By decomposing the propulsion force, horizontal movement and attitude fine-tuning are achieved. The control device coordinates the power of each thruster 101 to achieve six degrees of freedom of motion (forward / backward, left / right, up / down, roll, pitch, and yaw), adapting to complex seabed environments.

[0062] Further optimization of the scheme: the floating system includes foam floats 102, which are symmetrically fixed to the upper fixed plate 306 on the top of the robot frame by screws, and are used to adjust the buoyancy balance of the robot.

[0063] Foam floats 102 are symmetrically fixed to the top of the frame. By providing constant buoyancy to balance the robot's weight, they ensure that the center of buoyancy coincides with the center of gravity, allowing the robot to maintain a stable suspended posture in the water. The buoyancy can be precisely controlled by adjusting the number or density of the floats, reducing the energy consumption of the thruster 101.

[0064] Further optimization of the scheme: the mobile system includes four track groups 103 and one motor housing; the track groups 103 are symmetrically installed at the four corners of the bottom of the robot frame; the motor housing adopts a closed waterproof structure, is installed on the robot frame, and is connected to the drive wheel of the track group 103 through the end drive shaft to provide power to the track group 103.

[0065] Four track sets 103 are symmetrically distributed at the four corners of the bottom of the frame. The enclosed electric motor housing drives the track drive wheels, and the track structure is adapted to complex terrains such as sand and rocks. Steering is achieved through the differential movement of the two side tracks, and the lateral force of the horizontal thruster 101 enhances mobility. The waterproof design ensures reliable operation of the motor underwater.

[0066] The design is further optimized. The sealed chamber 2 includes an acrylic tube body 201, a hemispherical cover 202, a silicone pad 203, an O-ring 204, and a sealing cover 205. The front end of the acrylic tube is fixedly connected to the sealing cover 205, and the hemispherical cover 202 and the silicone pad 203 are fixed to the sealing cover 205 with bolts. A wire threading screw ring is provided at the end of the acrylic tube for the cable to pass through and to prevent seawater from entering. The acrylic tube body 201 is fixed between the upper fixing plate 306 by the upper fixing frame and the lower fixing frame.

[0067] The acrylic tube body 201 and the sealing cap 205 are sealed by a silicone gasket 203 and an O-ring 204. The hemispherical cover 202 provides a transparent observation window, and the cable threading screw ring compresses the cable to achieve waterproofing. The overall structure is securely installed by upper and lower fixing brackets to resist seawater pressure, ensure that the internal control device is isolated from the outside world, and guarantee the long-term operation of the equipment.

[0068] The design was further optimized, and the multi-degree-of-freedom robotic arm includes a shoulder joint system, an upper arm system, and a forearm system.

[0069] The shoulder joint system includes a robotic arm base 301, a servo motor mounting base 302, a single-axis servo motor 303, a dual-axis servo motor 304, and a shoulder joint U-shaped bracket 305. The robotic arm base 301 is fixedly connected to the upper fixed plate 306. The servo motor mounting base 302 is connected to the robotic arm base 301 via bearings and is fixedly connected to the single-axis servo motor 303. The output shaft of the single-axis servo motor 303 is connected to the robotic arm base 301. The dual-axis servo motor 304 is fixed to the shoulder joint U-shaped bracket 305.

[0070] The boom system includes an inner boom link 307, an outer boom link 308, a dual-axis servo motor 309 for the elbow joint, and a U-shaped bracket 310 for the elbow joint. The inner boom link 307 is connected by a copper column, the outer boom link 308 is connected to the inner boom link 307 by a copper column, and the output shaft of the dual-axis servo motor 309 for the elbow joint is connected to the U-shaped bracket 310 for the elbow joint.

[0071] The forearm system includes an inner forearm link 311, an outer forearm link 312, a dual-axis servo motor 313 of the wrist joint, a single-axis servo motor 314 of the wrist joint, and a U-shaped support 315 of the wrist joint; wherein, the outer forearm link 312 and the inner forearm link 311 are connected by copper pillars, the dual-axis servo motor 313 of the wrist joint is fixed to the inner forearm link 311 and connected to the U-shaped support 315 of the wrist joint, and the output shaft of the single-axis servo motor 314 of the wrist joint is fixedly connected to the U-shaped support 315 of the wrist joint;

[0072] Shoulder joint dual-axis servo 304, shoulder joint single-axis servo 303, elbow joint dual-axis servo 309, wrist joint dual-axis servo 313, and wrist joint single-axis servo 314 are all waterproof servos.

[0073] The further optimized design includes an upper gripper 316, a lower gripper 317, a gripper fixing component 318, and a gripper drive servo motor 319. The gripper fixing component 318 is connected to a wrist joint single-axis servo motor 314 via a multi-functional bracket. The gripper drive servo motor 319 is fixed to the gripper fixing component 318 and its output shaft is connected to the upper gripper 316. The lower gripper 317 is fixedly connected to the gripper fixing component 318. The upper gripper 316 and the lower gripper 317 adopt a flexible mesh folding structure and are arranged in a crescent shape.

[0074] The shoulder joint uses a single-axis servo motor (303) to control horizontal rotation, while a dual-axis servo motor controls pitch and lateral movement. The upper arm / forearm system uses dual-axis servos at the elbow and wrist joints to achieve multi-angle bending, and a single-axis servo motor to adjust wrist rotation. Waterproof servos at each joint work in tandem to achieve precise positioning and attitude adjustment of the robotic gripper in three-dimensional space.

[0075] The upper / lower grippers 317 employ a flexible mesh folding structure, with a crescent-shaped layout to increase the contact area with the sea urchin. The gripper drive servo 319 controls the opening and closing, and the flexible material disperses the gripping force, avoiding damage to the sea urchin spines or its own structure, thus achieving stable gripping of irregular objects.

[0076] The solution is further optimized. The visual communication system includes a wide-angle underwater camera and a rigid camera bracket. One end of the camera is connected to the O-ring 204 bolt on the upper part of the sealed chamber 2. The wide-angle underwater camera is mounted on the rigid camera bracket through a flange. The wide-angle underwater camera is connected to the image transmission module built into the sealed chamber 2 through a waterproof cable.

[0077] A wide-angle underwater camera is mounted on the top of the sealed chamber 2 via a rigid bracket to capture images of the underwater environment. The images are transmitted via waterproof cables to the processing module inside the chamber, which identifies the location and morphological characteristics of sea urchins, providing data support for the control device and guiding the robotic arm to perform precise operations.

[0078] refer to Figure 6 A method for harvesting sea urchins, comprising the following steps:

[0079] Step 1: Multimodal descent and real-time obstacle avoidance. The control device drives the vertical thruster 101 and the foam float 102 to coordinate and adjust the descent speed. At the same time, the horizontal thruster 101 is activated to perform lateral displacement. The distance to the obstacle is monitored in real time based on the laser ranging module. When the obstacle distance is <10mm, the obstacle avoidance path is generated through the PID control algorithm. After saving the current movement pulse count, the track group 103 is controlled to move horizontally to avoid the obstacle. Finally, the remaining pulse count is calculated to accurately reach the target point.

[0080] Step 2, sea urchin identification and autonomous positioning: After the robot touches the bottom, the visual communication system collects seabed images, the control device executes the MSW-YOLOv8 recognition algorithm, outputs the coordinates of the dense sea urchin area and drives the track group 103 to move to the target area.

[0081] Step 3, adaptive non-destructive harvesting: When the sea urchin enters the working range of the robotic arm, a six-degree-of-freedom robotic arm grasping trajectory is generated based on binocular vision data and inverse kinematics algorithm. The mesh robotic claw is driven to perform clamping with closed-loop force control, and the sea urchin is transferred to the collection chamber and the chamber cover is closed.

[0082] Step four, dynamic decision-making and stable return: real-time monitoring of the collection bin capacity. If it is not full, return to the new work area located in step two; if it is full, start the propulsion system to float up, and use the gyroscope to monitor the attitude angle and combine it with the PID controller to adjust the output of the thruster 101 to maintain navigation stability until it floats to the surface.

[0083] refer to Figures 7-14The robotic arm control unit of the industrial control computer sends commands to the wireless communication module via wireless transmission. The wireless communication module then wirelessly transmits the received commands to the main control circuit board. Next, the command signals are converted into signal data by the microprocessor on the main control circuit board and transmitted to each joint to control their movement. Simultaneously, the angle monitoring device for each joint collects and stores the changes in each joint in real time, transmitting the data to the angle monitoring circuit board. The signal data is then converted by the microprocessor and transmitted to the CAN data acquisition box and uploaded to the angle monitoring module of the industrial control computer. This completes the motion control and angle monitoring of the entire robotic arm.

[0084] The underwater fishing robot's walking control algorithm employs PID control technology. PID control consists of a proportional element K... p K, the points stage i Differential element K d Composed of three components, it boasts good applicability and a wide range of applications. In industrial production, due to its simplicity and reliability, when the structure and parameters of the controlled object are difficult to accurately grasp or when a precise mathematical model cannot be obtained through theoretical calculations, control requirements can be achieved through actual debugging combined with PID technology.

[0085] Considering the actual operating environment of underwater fishing robots, the control results are closely related to the values ​​of the three coefficients in the PID control. Different combinations are adopted based on the requirements of control accuracy and the controlled object, with each component playing a different role:

[0086] Proportional link K p The deviation signal e(t) reflects the control system's error. When a deviation occurs, to ensure the controlled object reaches the preset target value as quickly as possible, the controller amplifies the output control signal to reduce the deviation, achieving real-time regulation. When the deviation is zero, there is no control effect; this is considered differential regulation.

[0087] Points Section K i It is mainly used to eliminate steady-state error and increase stability. As long as the deviation is not zero, the integral action continues until the deviation is zero, so as to eliminate steady-state error.

[0088] Differential element K d It can reflect the changing trend of the deviation signal, reduce the adjustment time by using the early correction signal (before the deviation signal value becomes too large), and has the functions of reducing system overshoot and vibration, and improving response speed and dynamic performance.

[0089] In terms of attitude control, the motion attitude of an underwater fishing robot refers to the state of the three axes of the carrier in the air relative to a fixed coordinate system. It is one of the keys to the entire motion control system and the basic guarantee for its stable movement in water.

[0090] Regarding the yaw angle, the yaw angle is the x-axis of the carrier. tThe projection on the horizontal plane and the Earth's x-axis d The angle between them. To stabilize the yaw attitude, a PID controller is used, and its output control quantity acts on the thruster 101, directly affecting the underwater harvesting robot's navigation effect towards the sea urchin.

[0091] Regarding the roll angle, it is the angle between the plane of symmetry of the carrier and the vertical plane passing through the longitudinal axis of the carrier body. Its motion control method is similar to that of yaw, using a PID controller to stabilize the roll attitude angle at a preset value, and the output control quantity acts on the thruster 101, directly affecting the underwater fishing robot's ability to smoothly navigate towards the target.

[0092] In terms of depth control, when the underwater harvesting robot dives into the water to collect information on sea urchins and needs to perform depth positioning based on the diving depth, a PD controller is used for control.

[0093] The walking control algorithm for the underwater fishing robot is implemented based on STM32. The STM32's built-in timer outputs PWM values ​​to drive the motor. Combined with the STM32 encoder and the motor's built-in 13-line Hall encoder, an incremental PID algorithm is used to achieve autonomous positioning of the motor's odometer.

[0094] In the control algorithm, when the motor rotates, the Hall encoder's A and B phases record pulse signals. When phase A reads the rising edge of the pulse signal, before reading its falling edge, if phase B detects the rising edge of the pulse signal and phase A reads the falling edge before phase B reads its falling edge, and then phase B reads the falling edge again, it indicates that the motor is rotating forward, and the encoder pulse count is 4. Conversely, if the motor rotates backward, the current pulse value needs to be subtracted. In the STM32 control chassis's built-in timer, when both the rising and falling edges of phases A and B are detected as a single pulse value, the frequency division coefficient is set to 4. The number of pulses recorded for one revolution of the motor is Ax, and the encoded value for each revolution is 1, so Ax = 13 × 56 × 4. In the robot design phase, the number of pulses required to reach each target point can be determined in advance, Ay. Finally, Ay = number of motor revolutions + the pulse value recorded for the last partial revolution. Ay is used as the input error for the incremental PID algorithm, with the expected value set to 0. The returned PWM value is limited by the motor to prevent motor burnout before being applied to the motor. When the returned PWM value is 0, it means the destination has been reached. This allows the angular displacement required for each motor of the robot to rotate to be calculated in advance.

[0095] Actual testing revealed that the robot experienced tilting errors upon reaching the target point each time due to the precision issues of the Mecanum wheels. To correct this, an MPU6050 gyroscope was used to measure the tilt angle, and a PWM value was calculated using a PID controller and applied to the motors. During the robot's journey to the target location, if the laser ranging module detected an obstacle less than 10mm away, the total number of pulses counted (Az = number of revolutions × Ax + the currently counted pulses) was saved and then cleared to zero. The robot then moved to the left to perform obstacle avoidance, continuing towards the destination, with the wheel rotation pulse count being Aa (Aa = Ay - Az). Upon reaching the destination, the robot moved to the right, the same distance as when it moved to the left during obstacle avoidance, thus achieving obstacle avoidance and accurately reaching the destination.

[0096] The robot's vision system uses an improved YOLOv8 detection algorithm to identify sea urchins. The YOLOv8 model mainly consists of three parts: Backbone, Neck, and Head. The Backbone part uses a series of convolutional and deconvolutional layers to extract features. The Neck part uses multi-scale fusion technology to fuse feature maps from different stages of the Backbone to enhance expressiveness. The Head part is responsible for the final target detection and classification, which also includes a series of convolutional and deconvolutional layers.

[0097] One improvement to the MSW-YOLOv8 algorithm model is the addition of a lightweight MixedLocalChannelAttention (MLCA) module to the C2f module, enhancing its ability to extract channel and spatial information. The structure is shown in the figure below. The improved M-C2f module replaces a portion of the original C2f module. The C2f module, as a residual module in the YOLOv8 network, serves two purposes: downsampling and feature extraction. The BottleNeck part reduces computational cost. By adding the BottleNeck part, the C2f module enriches the information flow while reducing computation, thereby improving its feature representation ability. To further enrich the gradient flow of the C2f module and enhance its feature representation ability, the MLCA attention mechanism is introduced into the BottleNeck part, forming the M-BottleNeck. The MLCA attention mechanism recalculates the weights at each position by fusing spatial and channel information, without changing the number of channels or increasing the model's computational cost, while also improving the model's recognition accuracy.

[0098] The second improvement to the MSW-YOLOv8 model is the introduction of the WIoU (Weighted Intersection over Union) loss function to address the bias caused by the loss function in evaluating the results. The design of the WIoU loss function is as follows: First, the IoU score between the predicted and ground truth boxes is calculated to measure their overlap. Then, the maximum distance between the center points of the bounding boxes is determined, and the region between the two boxes is calculated. This region measures the relationship between the boxes. Next, a weight coefficient is calculated based on this region, which is used to weight the IoU score. Finally, the introduction of the region and weight coefficient between the boxes allows the algorithm to more accurately evaluate the object detection results. This method helps to more accurately evaluate the accuracy and relevance of object detection. The formula for WIoU is as follows:

[0099]

[0100] Where n represents the number of marked defect boxes, b i G represents the coordinates of the i-th prediction box. i Represents the coordinates of the i-th ground truth bounding box, IoU(b i ,g i ) represents the IoU value between the predicted bounding box and the ground truth bounding box, w i This represents the weight value.

[0101] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0102] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A composite sea urchin harvesting robot, characterized in that, include: A robot mobile chassis (1) includes a robot frame, a propulsion system, a floating system and a moving system. The moving system is symmetrically installed on both sides of the bottom of the robot frame, the floating system is symmetrically installed on the top of the robot frame, and the propulsion system is installed between the moving system and the floating system. A sealed compartment (2) is mounted on the robot frame; The robotic arm device (3) includes a multi-degree-of-freedom robotic arm and a robotic claw. The multi-degree-of-freedom robotic arm is fixed to the top of the front end of the robot frame by a robotic arm base (301), and the robotic claw is mounted on the front end of the multi-degree-of-freedom robotic arm by a wrist joint dual-axis servo motor (313). A visual communication system, which is installed on top of the front end of the sealed chamber (2); A control device is installed inside the sealed chamber (2).

2. The composite sea urchin harvesting robot according to claim 1, characterized in that: The propulsion system includes six underwater thrusters (101), two of which are vertical thrusters (101) and four are horizontal thrusters (101). The vertical thrusters (101) are installed on both sides of the center line of the robot frame in a dual-axis symmetrical layout, with the positive output port pointing vertically downward. The horizontal thrusters (101) are arranged in a spatial array at a 45° tilt angle, fixedly installed in the four diagonal gaps of the robot frame, and connected to the control device in the sealed chamber (2) through waterproof cables.

3. The composite sea urchin harvesting robot according to claim 1, characterized in that: The floating system includes foam floats (102), which are symmetrically fixed to the upper fixed plate (306) on the top of the robot frame by screws, for adjusting the buoyancy balance of the robot.

4. The composite sea urchin harvesting robot according to claim 1, characterized in that: The mobile system includes four track sets (103) and a motor housing; the track sets (103) are symmetrically installed at the four corners of the bottom of the robot frame; the motor housing adopts a closed waterproof structure, is installed on the robot frame, and is connected to the drive wheel of the track set (103) through the end drive shaft to provide power to the track set (103).

5. The composite sea urchin harvesting robot according to claim 3, characterized in that: The sealed chamber (2) includes an acrylic tube body (201), a hemispherical cover (202), a silicone pad (203), an O-ring (204), and a sealing cover (205); the front end of the acrylic tube is fixedly connected to the sealing cover (205), and the hemispherical cover (202) and the silicone pad (203) are fixed to the sealing cover (205) by bolts; the end of the acrylic tube is provided with a wire threading screw ring for the cable to pass through and to prevent seawater from entering; the acrylic tube body (201) is fixed between the upper fixing plate (306) by the upper fixing frame and the lower fixing frame.

6. The composite sea urchin harvesting robot according to claim 1, characterized in that: The multi-degree-of-freedom robotic arm includes a shoulder joint system, an upper arm system, and a forearm system; The shoulder joint system includes a robotic arm base (301), a servo motor mounting base (302), a single-axis servo motor for the shoulder joint (303), a dual-axis servo motor for the shoulder joint (304), and a shoulder joint U-shaped bracket (305); wherein, the robotic arm base (301) is fixedly connected to the upper fixing plate (306), the servo motor mounting base (302) is connected to the robotic arm base (301) through bearings and is fixedly connected to the single-axis servo motor for the shoulder joint (303), the output shaft of the single-axis servo motor for the shoulder joint (303) is connected to the robotic arm base (301), and the dual-axis servo motor for the shoulder joint (304) is fixed to the shoulder joint U-shaped bracket (305); The boom system includes an inner boom link (307), an outer boom link (308), a dual-axis servo motor for the elbow joint (309), and a U-shaped bracket for the elbow joint (310); wherein, the inner boom link (307) is connected by a copper column, the outer boom link (308) is connected to the inner boom link (307) by a copper column, and the output shaft of the dual-axis servo motor for the elbow joint (309) is connected to the U-shaped bracket for the elbow joint (310); The forearm system includes an inner forearm link (311), an outer forearm link (312), a dual-axis servo motor (313) of the wrist joint, a single-axis servo motor (314) of the wrist joint, and a U-shaped support (315) of the wrist joint; wherein, the outer forearm link (312) and the inner forearm link (311) are connected by copper pillars, the dual-axis servo motor (313) of the wrist joint is fixed to the inner forearm link (311) and connected to the U-shaped support (315) of the wrist joint, and the output shaft of the single-axis servo motor (314) of the wrist joint is fixedly connected to the U-shaped support (315) of the wrist joint; The shoulder joint dual-axis servo motor (304), shoulder joint single-axis servo motor (303), elbow joint dual-axis servo motor (309), wrist joint dual-axis servo motor (313), and wrist joint single-axis servo motor (314) are all waterproof servo motors.

7. A composite sea urchin harvesting robot according to claim 6, characterized in that: The mechanical gripper includes an upper gripper (316), a lower gripper (317), a gripper fixing member (318), and a gripper drive servo motor (319); wherein, the gripper fixing member (318) is connected to the wrist joint single-axis servo motor (314) through a multi-functional bracket, the gripper drive servo motor (319) is fixed to the gripper fixing member (318) and its output shaft is connected to the upper gripper (316), and the lower gripper (317) is fixedly connected to the gripper fixing member (318); the upper gripper (316) and the lower gripper (317) adopt a flexible mesh folding structure and are arranged in a crescent shape.

8. A composite sea urchin harvesting robot according to claim 5, characterized in that: The visual communication system includes a wide-angle underwater camera and a rigid camera bracket, one end of which is bolted to the O-ring (204) on the upper part of the sealed chamber (2). The wide-angle underwater camera is mounted on the rigid camera bracket via a flange. The wide-angle underwater camera is connected to the image transmission module built into the sealed chamber (2) via a waterproof cable.

9. A method for harvesting sea urchins, based on the composite sea urchin harvesting robot according to any one of claims 1-8, comprising the following steps: Step 1: Multimodal descent and real-time obstacle avoidance. The control device drives the vertical thruster (101) and foam float (102) to coordinate and adjust the descent speed. At the same time, the horizontal thruster (101) is started to perform lateral displacement. The distance to the obstacle is monitored in real time based on the laser ranging module. When the obstacle distance is <10mm, the obstacle avoidance path is generated through the PID control algorithm. After saving the current movement pulse count, the track group (103) is controlled to move to avoid the obstacle. Finally, the remaining pulse count is calculated to accurately reach the target point. Step 2, sea urchin identification and autonomous positioning: After the robot touches the bottom, the visual communication system collects seabed images, the control device executes the MSW-YOLOv8 recognition algorithm, outputs the coordinates of the dense sea urchin area and drives the track group (103) to move to the target area. Step 3, adaptive non-destructive harvesting: When the sea urchin enters the working range of the robotic arm, a six-degree-of-freedom robotic arm grasping trajectory is generated based on binocular vision data and inverse kinematics algorithm. The mesh robotic claw is driven to perform clamping with closed-loop force control, and the sea urchin is transferred to the collection chamber and the chamber cover is closed. Step 4, dynamic decision-making and stable return: monitor the capacity of the collection bin in real time. If it is not full, return to the new work area in Step 2; if it is full, start the propulsion system to float up, and use the gyroscope to monitor the attitude angle and adjust the output of the thruster (101) in combination with the PID controller to maintain navigation stability until it floats up.

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