Dual-machine cooperation redundant degree of freedom mobile parallel composite robot and cooperation method thereof

Abstract

The application discloses a double-machine cooperation redundant degree of freedom mobile parallel composite robot and a cooperation method thereof, the robot comprises a planar moving platform for omnidirectional movement, a single degree of freedom lifting platform is installed on the top of the planar moving platform, a six degree of freedom pose adjusting platform is installed on the lifting output end of the single degree of freedom lifting platform, the output end of the six degree of freedom pose adjusting platform is a six degree of freedom adjusting pose moving platform, and a workpiece support for bearing a workpiece is installed on the moving platform. The cooperation method comprises the following steps: visual identification and coordinate system conversion; master-slave machine cooperative coarse adjustment and parking; visual closed loop fine pose adjustment; docking completion and resetting. The robot adopts the above structural design and cooperation method, and flexible transfer and high-precision stable assembly of heavy workpieces are realized.

Description

Technical Field

[0001] This invention belongs to the field of mobile assembly robot technology, specifically relating to a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot and its cooperative method. Background Technology

[0002] With the development of modern manufacturing, the demand for the transfer, orientation adjustment, and assembly of large-size and heavy components in unstructured industrial environments such as aviation, aerospace, shipbuilding, and large equipment is increasing. Traditional manual labor methods struggle to simultaneously guarantee efficiency and precision in the assembly of large components. Therefore, mobile robots combining robotic arms with automated guided vehicles (AGVs), i.e., mobile platforms, have been widely applied in the industrial field. Among various robotic arms, parallel robots, due to their inherent high rigidity and high positioning accuracy, have advantages over serial robots. Mobile parallel robots, formed by combining parallel robots with mobile platforms, inherit the wide-range mobility of mobile platforms while leveraging the high load and high precision characteristics of six-degree-of-freedom orientation adjustment platforms. They demonstrate great application potential in smart factories for the large-scale handling and high-precision orientation adjustment of large components, perfectly meeting the core assembly needs of "large-scale transfer" and "small-scale precise orientation adjustment" in smart factories.

[0003] However, most of the current mainstream six-DOF parallel robots adopt the traditional six-branch configuration, such as the Stewart platform. When such robots are mounted on mobile platforms with limited size and load-bearing capacity, their own weight and volume not only make it difficult to meet the requirements of lightweighting, but also limit the range of their pose adjustment workspace, which becomes a bottleneck restricting their application efficiency.

[0004] Currently, some mobile robots only possess simple grasping or handling functions, making it difficult to meet complex assembly requirements. Furthermore, many mobile assembly robots suffer from insufficient rigidity due to their serial arm structures. For example, the serial structure of the first, second, and third arms connected in sequence, as used in patent CN105500333A, and the integrated multi-joint serial robotic arm disclosed in CN223211381U, exhibit open-chain structures prone to deformation under heavy loads, resulting in poor rigidity and difficulty meeting the high precision and stability requirements for assembling large components. Moreover, some six-degree-of-freedom (6DOF) mobile assembly robots employing a six-DOF attitude adjustment platform also have design flaws. For instance, the design in patent CN104802151A places the parallel platform above the lifting mechanism and then installs it as a whole on the mobile platform. This vertically stacked structure leads to an excessively high center of gravity, resulting in poor stability when carrying large, heavy workpieces, hindering mobile assembly, and making it unsuitable for confined spaces with height restrictions.

[0005] Furthermore, the aforementioned mobile robots suffer from inaccurate positioning and complex assembly processes during assembly, which reduces assembly accuracy and efficiency. Summary of the Invention

[0006] This invention is proposed to solve the problems existing in the prior art. Its purpose is to provide a collaborative method for a dual-machine collaborative redundant degree-of-freedom mobile parallel composite robot with high rigidity, large workspace and multi-level attitude adjustment capability, as well as a dual-machine collaborative redundant degree-of-freedom mobile parallel composite robot.

[0007] The cooperative method for a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot provided by the present invention includes the following steps: S1: Visual Recognition and Coordinate System Transformation Fix the robot host in the designated position, and place the robot slave in the position opposite to the robot host to determine the roles of the robot host and the robot slave. The robot host's binocular camera acquires images of the workpiece at the end of the opposing robot slave. The central controller of the robot host preprocesses the images and uses an ellipse edge enhancement detection algorithm to identify the circular features of the workpiece end face. It fits an ellipse and extracts the coordinates of the ellipse center point in the pixel coordinate system, as well as the major and minor axis parameters of the ellipse. Furthermore, in S1, based on the intrinsic parameters and depth information of the robot's binocular camera, the pixel coordinates of the ellipse center point are converted into three-dimensional coordinates in the camera coordinate system.

[0008] Furthermore, in S1, based on the preset rotation and translation matrices between the camera coordinate system and the static platform coordinate system, the three-dimensional coordinates in the camera coordinate system are converted into three-dimensional pose data in the static platform coordinate system with the static platform of the robot host as the reference. At the same time, the normal attitude angle of the workpiece end face is calculated according to the major axis direction of the ellipse.

[0009] Furthermore, the central controller receives images captured by the binocular cameras, preprocesses the images, and uses an elliptical edge enhancement detection algorithm to identify the circular features of the end face of the workpiece at the end of the opposing robot. Specifically, the central controller extracts image edges using Canny edge detection, calculates the approximate circularity of the contour, and performs ellipse fitting on contours containing at least 5 points to extract the coordinates of the ellipse center point in the pixel coordinate system and the major and minor axis parameters of the ellipse. Simultaneously, it obtains the depth value corresponding to the ellipse center point by combining the depth information from the binocular cameras, and converts the pixel coordinates into 3D coordinates in the camera coordinate system based on the camera intrinsic parameters. Then, based on the preset rotation and translation matrices between the camera coordinate system and the static platform coordinate system, it converts the 3D coordinates in the camera coordinate system into 3D pose data in the static platform coordinate system based on the local static platform, and calculates the normal attitude angle of the workpiece end face according to the major axis direction of the ellipse.

[0010] S2: Master-Slave Coordination and Parking The central controller of the robot host calculates the relative pose error between the robot host and the opposing robot slave based on the converted pose data. After the rough adjustment is completed, the central controller of the robot host negotiates with the opposing robot slave via wireless communication to re-determine the roles of the robot host and the robot slave. Then, the robot slave executes the parking mechanism to lift and rigidly fix the robot slave's frame to the ground, while the robot host remains in a moving state. Furthermore, in S2, if the relative pose error exceeds the joint compensation range of the robot host's six-degree-of-freedom posture adjustment platform and single-degree-of-freedom lifting platform, the robot host's central controller sends a correction command to the planar motion platform, driving the drive wheel set to make a slight movement until the relative pose error enters the compensation range.

[0011] Furthermore, the central controller calculates the relative pose error between the robot master and the opposing robot slave based on the converted pose data, and determines whether this error is within the combined compensable range of the six-degree-of-freedom pose adjustment platform and the single-degree-of-freedom lifting platform. If it exceeds the range, the central controller sends a correction command to the planar motion platform, driving the drive wheel set to make a slight movement until the relative pose error enters the compensable range. After coarse adjustment, the central controller determines the roles of the robot master and robot slave through wireless communication negotiation with the opposing robot slave, and controls the robot slave to execute the parking mechanism to lift, rigidly fixing the frame to the ground, while the robot master remains movable.

[0012] S3: Visual Closed-Loop Fine-Tuning The robot slave's binocular camera continuously acquires images at a set frequency, repeating S1 to obtain real-time relative pose; The robot slave's central controller calls the pre-stored 3-PRPS parallel mechanism inverse kinematics model to solve the current relative pose error into the movement of the first linear joint and the extension of the second linear joint in each branch of the six-degree-of-freedom attitude adjustment platform. Furthermore, in S3, according to the master-slave collaboration strategy, the central controller of the robot slave is assigned adjustment tasks: the robot master undertakes the main position and attitude compensation, and the robot slave performs minor compensation within its own controllable range; the central controller of the robot slave generates corresponding control commands to drive the first servo motor and the second servo motor of each branch, so that the moving platform moves the workpiece to gradually approach the target pose.

[0013] Furthermore, in S3, during the adjustment process, if a large-scale vertical compensation is required, the central controller of the robot slave simultaneously sends instructions to the electric actuator of the single-degree-of-freedom lifting platform to collaboratively complete the lifting compensation.

[0014] Furthermore, in the stationary state, the central controller of the robot host receives real-time images from the binocular camera at a set frequency and repeats the aforementioned visual recognition and coordinate system transformation steps to obtain the real-time relative pose. The central controller of the robot host calls the pre-stored inverse kinematics model of the 3-PRPS parallel mechanism to calculate the current relative pose error as the movement of the first linear joint and the extension of the second linear joint in each branch of the six-degree-of-freedom attitude adjustment platform. According to the master-slave cooperative strategy, the central controller allocates adjustment tasks: the robot host undertakes the main position and attitude compensation, while the robot slave performs minor compensation within its controllable range. The central controller of the robot host generates corresponding control commands to drive the first and second servo motors of each branch, causing the moving platform to gradually approach the target pose. During the adjustment process, if large-scale compensation in the vertical direction is required, the central controller simultaneously sends commands to the electric push rod of the single-degree-of-freedom lifting platform to collaboratively complete the lifting compensation.

[0015] S4: Docking Completed and Reset When the real-time relative pose error is less than the preset docking tolerance, the central controller of the robot slave executes the final docking action, and the control platform of the robot slave moves along the docking direction until the workpiece contacts or is inserted into the workpiece of the opposing robot host. After docking is completed, the robot's binocular camera re-verifies the pose. Once the pose is confirmed to be correct, the robot's central controller sends a completion signal. The robot's parking mechanism is released from lifting, and all platforms are reset to their initial positions, thus ending the mission.

[0016] Furthermore, when the real-time relative pose error is less than the preset docking tolerance, the central controller executes the final docking action, controlling the moving platform to move along the docking direction until the workpiece contacts or inserts into the opposing workpiece. After docking is completed, the binocular camera re-verifies the pose, and after confirming that there are no errors, the central controller sends a completion signal. The parking mechanism releases the lifting mechanism, each platform resets to its initial pose, and the task ends.

[0017] Through the above control methods, the present invention achieves fully automated control of the entire process from visual recognition, coordinate transformation, coarse adjustment correction, master-slave collaboration, fine adjustment closed loop to docking completion, which significantly improves the accuracy, efficiency and stability of dual-machine collaboration.

[0018] The present invention relates to a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot, comprising a planar mobile platform for omnidirectional movement, a single degree-of-freedom lifting platform mounted on the top of the planar mobile platform, a six degree-of-freedom attitude adjustment platform mounted on the lifting output end of the single degree-of-freedom lifting platform, and a six-degree-of-freedom attitude adjustment platform whose output end is a six-degree-of-freedom adjustable posture moving platform, and a workpiece support for carrying the workpiece mounted on the moving platform. The six-degree-of-freedom attitude adjustment platform includes a static platform fixed to the single-degree-of-freedom lifting platform, and a binocular camera is fixed on the static platform for acquiring relative attitude information of the docking workpiece; The planar motion platform is equipped with a central controller, which is electrically connected to the binocular camera, the drive wheel group of the planar motion platform, the electric push rod of the single-degree-of-freedom lifting platform, and the drive motors of the six-degree-of-freedom attitude adjustment platform. The central controller is configured as follows: It receives images captured by a binocular camera, identifies the end face features of the workpiece at the end of the opposing robot, and calculates the three-dimensional pose of the workpiece relative to the stationary platform of the robot based on a preset coordinate system transformation relationship. Based on the calculated pose error, and combined with the pre-stored inverse kinematics model of the six-degree-of-freedom attitude adjustment platform, control commands for each branch drive motor are generated. According to the master-slave collaboration strategy, it communicates with the host robot and the slave robot to control the planar moving platform, single-degree-of-freedom lifting platform and six-degree-of-freedom attitude adjustment platform of the host robot and the slave robot to perform coarse adjustment, pause, fine adjustment and docking actions in stages to realize dual-machine collaborative assembly. The six-degree-of-freedom attitude adjustment platform includes three identical first, second, and third branches. The bottom of each branch is arranged in a triangular enclosure on the static platform through a first linear joint, and the top of each branch is connected to the moving platform through a ball joint. Each branch includes a first linear joint, a revolute joint, a second linear joint, and a ball joint connected in sequence. The translation output end of the first linear joint is connected to the revolute joint, the rotation output end of the revolute joint is connected to the second linear joint, and the output end of the second linear joint is fitted with a ball joint. The first linear pair is a guide rail and lead screw linear module, including a guide rail seat, a lead screw and a slider. The slider is driven by a branch second servo motor through a second synchronous belt module. The second linear pair is an electric cylinder, which includes an electric cylinder body and an electric cylinder telescopic rod. The electric cylinder telescopic rod is driven by a branch first servo motor through a first synchronous belt module. The rotary pair includes a rotary pair module and a rotary pair seat. The rotary pair module is installed on the upper end of the slider, and its rotation output end is fixedly connected to the cylinder body of the electric cylinder. The ball joint includes a ball head connected to the telescopic rod of the electric cylinder and a ball joint seat connected to the moving platform, with a ball sleeve between the ball head and the ball joint seat.

[0019] Furthermore, the single-degree-of-freedom lifting platform includes a single-degree-of-freedom lifting platform frame and an electric push rod installed therein, with the telescopic end of the electric push rod fixedly connected to the static platform of the six-degree-of-freedom attitude adjustment platform. The planar mobile platform includes a frame, with a drive wheel set and a parking mechanism at the lower end of the frame, and a lidar for environmental perception and navigation at the upper end of the frame; The drive wheelset includes a wheelset servo motor, a planetary reducer, and a Mecanum wheel. The output end of the wheelset servo motor is connected to the Mecanum wheel via the planetary reducer. The planetary reducer is connected to the frame via a shock-absorbing module.

[0020] Furthermore, the binocular camera is installed at a preset tilt angle between its optical axis and the static platform plane to cover the field of view of the workpiece at the end of the opposing robot. The central controller is also connected to an emergency stop switch and a start / stop switch, and is equipped with a wireless communication module for communicating with external systems.

[0021] The beneficial effects of the dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot of the present invention are as follows: This invention consists of a three-level modular structure: a workpiece support, a parallel attitude adjustment robot, and a planar moving platform. The workpiece support is used to support and clamp large cylindrical parts. The parallel attitude adjustment robot adopts a three-branch six-degree-of-freedom (3-PRPS) parallel configuration to achieve high rigidity, large working space, and micron-level attitude fine adjustment of the moving platform. The planar moving platform is based on a topology-optimized welding frame and omnidirectional Mecanum wheel drive, which has the ability to flexibly transfer loads over a wide range. It also provides vehicle body stability and coarse height adjustment before assembly through a parking mechanism and a lifting mechanism.

[0022] This invention integrates a binocular camera and a lidar to achieve environmental perception, visual feedback closed-loop control, and dual-machine collaborative operation. It constructs a multi-level assembly process that ranges from coarse adjustment to fine adjustment, thereby significantly improving the assembly efficiency, accuracy, and system flexibility of large components.

[0023] This invention proposes a three-branch, six-degree-of-freedom (3-PRPS) parallel robot configuration. This design significantly reduces the complexity and weight of the mechanism while ensuring high rigidity, and achieves a larger pose workspace, thus facilitating component docking tasks. Simultaneously, this invention also includes a mobile platform to meet the dual requirements of motion stability and flexibility during high-precision docking. Ultimately, by assembling multiple such composite robots into a unified perception and collaborative operation system, the aim is to overcome the shortcomings of existing technologies and achieve automated, streamlined, and intelligent docking and assembly of large cylindrical components. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the planar moving platform provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the single-degree-of-freedom lifting platform provided in an embodiment of the present invention; Figure 4This is a schematic diagram of the structure of the six-degree-of-freedom attitude adjustment platform provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the drive wheel assembly provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the six-degree-of-freedom attitude adjustment platform branch provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the ball joint structure provided in an embodiment of the present invention; Figure 8 This is a schematic diagram of the dual-machine docking assembly provided in an embodiment of the present invention; Figure 9 This is a flowchart of the collaborative method for a dual-machine collaborative redundant degree-of-freedom mobile parallel composite robot provided in an embodiment of the present invention.

[0025] in: 1. Outer shell; 2. Planar moving platform; 3. Workpiece support; 4. Workpiece; 5. Six-degree-of-freedom attitude adjustment platform; 6. Single-degree-of-freedom lifting platform; 7. Emergency stop switch; 8. Start / stop switch; 9. Frame; 10. Outer shell mounting bracket; 11. LiDAR; 12. Drive wheel set; 13. Battery; 14. Parking mechanism control module; 15. Parking mechanism; 16. Moving platform controller; 17. Single-degree-of-freedom lifting platform control module; 18. Parking mechanism remote control module; 19. Wheel set motor driver; 20. Six-degree-of-freedom attitude adjustment platform controller; 21. Single-degree-of-freedom lifting platform remote control module; 22. Central controller; 23. Single-degree-of-freedom lifting platform frame; 24. Electric push rod; 25. Moving platform; 26. First branch chain; 27. Second branch chain 28. Third branch chain; 29. ​​Static platform; 30. Binocular camera; 31. Wheelset servo motor; 32. Planetary reducer; 33. Shock absorption module; 34. Wheelset bracket; 35. Mecanum wheel; 36. Ball joint; 37. Electric cylinder telescopic rod; 38. Electric cylinder body; 39. First branch chain servo motor; 40. First synchronous belt module; 41. Rotary pair module; 42. Bearing end cover; 43. Guide rail seat; 44. Lead screw; 45. Guide rail; 46. Rotary pair seat; 47. Slider; 48. Second branch chain servo motor; 49. Flange; 50. Second synchronous belt module; 51. Ball joint seat; 52. Ball sleeve; 53. Ball head. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments: like Figures 1 to 9As shown, the dual-machine collaborative redundant degree-of-freedom mobile parallel composite robot includes a planar mobile platform 2 for omnidirectional movement, a single-degree-of-freedom lifting platform 6 installed on the top of the planar mobile platform 2, a six-degree-of-freedom attitude adjustment platform 5 installed at the lifting output end of the single-degree-of-freedom lifting platform 6, and a six-degree-of-freedom attitude adjustment platform 25 whose output end is a six-degree-of-freedom adjustable motion platform 25. A workpiece support 3 for carrying the workpiece 4 is installed on the motion platform 25.

[0027] The six-degree-of-freedom attitude adjustment platform 5 includes a static platform 29 fixed to the single-degree-of-freedom lifting platform 6, and a binocular camera 30 for acquiring relative pose information of the docking workpiece is fixed on the static platform 29. The planar moving platform 2 is equipped with a central controller 22, which is electrically connected to the binocular camera 30, the drive wheel group 12 of the planar moving platform 2, the electric push rod 24 of the single-degree-of-freedom lifting platform 6, and the drive motors of the six-degree-of-freedom attitude adjustment platform 5. The central controller 22 is configured as follows: The system receives images captured by the binocular camera 30, identifies the end face features of the workpiece 4 at the end of the opposing robot, and calculates the three-dimensional pose of the workpiece relative to the local static platform 29 based on a preset coordinate system transformation relationship. Based on the calculated pose error, and combined with the pre-stored inverse kinematics model of the six-degree-of-freedom pose adjustment platform 5, control commands for each branch drive motor are generated. Following the master-slave collaboration strategy, it communicates with the host robot and the slave robot to control the planar moving platform 2, the single-degree-of-freedom lifting platform 6 and the six-degree-of-freedom attitude adjustment platform 5 of the host robot and the slave robot to perform coarse adjustment, pause, fine adjustment and docking actions in stages, so as to realize the dual-machine collaborative assembly.

[0028] The planar mobile platform 2 includes a frame 9 as the main assembly body. The lower end of the frame 9 is provided with a drive wheel set 12 and a parking mechanism 15. The drive wheel set 12 can perform a wide range of planar movements, and the parking mechanism 15 can lift the robot as a whole and fix it to the ground. A lidar 11 for environmental perception and navigation is provided on the upper end of the frame 9.

[0029] The drive wheel set 12 includes a wheel set servo motor 31, a planetary reducer 32 and a Mecanum wheel 35. The output end of the wheel set servo motor 31 is connected to the Mecanum wheel 35 via the planetary reducer 32. The planetary reducer 32 is connected to the frame 9 via a transmission seat and a shock absorption module 33.

[0030] The single-degree-of-freedom lifting platform 6 includes a single-degree-of-freedom lifting platform frame 23 and an electric push rod 24 installed therein. The telescopic end of the electric push rod 24 is fixedly connected to the static platform 29 of the six-degree-of-freedom attitude adjustment platform 5.

[0031] The six-degree-of-freedom attitude adjustment platform 5 includes three identical first branches 26, second branches 27 and third branches 28. The bottom of each branch is arranged in a triangle on the static platform 29 through a first linear joint, and the top of each branch is connected to the moving platform 25 through a ball joint 36. Each branch includes a first linear joint, a revolute joint, a second linear joint, and a ball joint 36 connected in sequence. The translation output end of the first linear joint is connected to the revolute joint, the rotation output end of the revolute joint is connected to the second linear joint, and the output end of the second linear joint is equipped with the ball joint 36.

[0032] The first linear pair is a guide rail and lead screw linear module, including a guide rail seat 43, a lead screw 44 and a slider 47. The slider 47 is driven by a branch second servo motor 48 through a second synchronous belt module 50. The second linear pair is an electric cylinder, including an electric cylinder body 38 and an electric cylinder telescopic rod 37. The electric cylinder telescopic rod 37 is driven by a branch first servo motor 39 through a first synchronous belt module 40. The rotary pair includes a rotary pair module 41 and a rotary pair seat 46. The rotary pair module 41 is mounted on the upper end of the slider 47, and its rotation output end is fixedly connected to the cylinder body 38 of the electric cylinder.

[0033] The ball joint 36 includes a ball head 53 connected to the electric cylinder telescopic rod 37 and a ball joint seat 51 connected to the moving platform 25. A ball sleeve 52 is provided between the ball head 53 and the ball joint seat 51.

[0034] The binocular camera 30 is installed at a preset tilt angle between its optical axis and the plane of the static platform 29, so as to cover the field of view of the workpiece 4 at the end of the opposing robot.

[0035] The central controller 22 is also connected to an emergency stop switch 7 and a start / stop switch 8, and is equipped with a wireless communication module for communicating with external systems.

[0036] Specifically, the planar moving platform 2 is used to realize the overall large-range movement and transfer of the system; the six-degree-of-freedom attitude adjustment platform 5 is used to realize the precise attitude adjustment and high-precision spatial positioning of the workpiece 4; the single-degree-of-freedom lifting platform 6 is used to realize the large-range adjustment of the system's working range in the vertical direction; and the electrical control module is used to drive the movement of components such as the planar moving platform 2 and the six-degree-of-freedom attitude adjustment platform 5.

[0037] The connection methods of each component are as follows: the single-degree-of-freedom lifting platform 6 is bolted to the top of the planar moving platform 2; the six-degree-of-freedom attitude adjustment platform 5 is bolted to the top of the single-degree-of-freedom lifting platform 6; the workpiece bracket 3 is bolted to the moving platform of the six-degree-of-freedom attitude adjustment platform 5; the workpiece 4 is clamped and fixed by the workpiece bracket 3. The electrical control module is bolted to the inside of the vehicle body of the planar moving platform 2.

[0038] Workpiece 4 can be of different sizes and models, and a matching workpiece support 3 can be selected.

[0039] Specifically, in addition to the frame 9, the planar mobile platform 2 also includes a shell mounting bracket 10, a lidar 11, a drive wheel set 12, and a parking mechanism 15.

[0040] The parking mechanism 15 is bolted to the frame 9 and is used to lift the robot as a whole and fix it to the ground after the planar moving platform 2 reaches the designated position to ensure stability during assembly operations.

[0041] The six-DOF attitude adjustment platform 5 consists of a moving platform 25, a first branch 26, a second branch 27, a third branch 28, and a stationary platform 29, with the first branch 26, second branch 27, and third branch 28 having identical structures. The moving platform 25 serves as the robot's end effector, used to output pose; the first branch 26, second branch 27, and third branch 28 are bolted to the stationary platform 29. A binocular camera 30 is also mounted on the stationary platform 29, used for real-time measurement of the relative pose of the workpiece 4 during the assembly process.

[0042] Each branch chain consists of the following components: ball joint 36, electric cylinder telescopic rod 37, electric cylinder body 38, branch chain first servo motor 39, first synchronous belt module 40, rotary joint module 41, bearing end cover 42, guide rail seat 43, lead screw 44, guide rail 45, rotary joint seat 46, slider 47, branch chain second servo motor 48, flange 49, and second synchronous belt module 50.

[0043] The electric cylinder telescopic rod 37 and the electric cylinder body 38 together form an electric cylinder, used to realize the horizontal movement of the branch in one degree of freedom. The electric cylinder is driven by the branch's first servo motor 39 through the first synchronous belt module 40.

[0044] The guide rail base 43, lead screw 44, guide rail 45, and slider 47 together form a linear module, which is used to realize the horizontal movement of the branch in another degree of freedom. This linear module is driven by the branch's second servo motor 48 through the second synchronous belt module 50.

[0045] The ball joint 36 includes a ball joint seat 51, a ball sleeve 52, and a ball head 53, and is used to realize three-degree-of-freedom rotation at the end of the branch.

[0046] The rotary joint module 41 includes a rotating shaft and bearings, which are mounted on the rotary joint seat 46 via the bearings. Both ends are fixed by bearing end caps 42, enabling single-degree-of-freedom rotation of the branch. The rotary joint seat 46 is fixed to the slider 47 by bolts.

[0047] The branch second servo motor 48 and the linear module are respectively mounted on the flange 49 by bolts.

[0048] The electronic control module includes a battery 13, a parking mechanism control module 14, a mobile platform controller 16, a single-degree-of-freedom lifting platform control module 17, a parking mechanism remote control module 18, a wheel motor driver 19, a six-degree-of-freedom attitude adjustment platform controller 20, a single-degree-of-freedom lifting platform remote control module 21, and a central controller 22. Each module is fixed to the interior of the planar mobile platform 2 by bolts.

[0049] like Figure 1 The diagram shown is a structural schematic of the entire machine of this invention. The overall structure includes a shell 1, a planar moving platform 2, a workpiece support 3, a workpiece 4, a six-degree-of-freedom attitude adjustment platform 5, a single-degree-of-freedom lifting platform 6, an emergency stop switch 7, and a start / stop switch 8. The shell 1 protects the internal structures of the planar moving platform 2, the six-degree-of-freedom attitude adjustment platform 5, and the single-degree-of-freedom lifting platform 6. The emergency stop switch 7 is used to stop the robot's operation in case of emergencies, and the start / stop switch 8 is used to control the robot's opening and closing.

[0050] like Figure 2 The diagram shows the internal structure of the planar mobile platform 2 of the present invention. The planar mobile platform 2 includes a frame 9 for support, a housing mounting bracket 10 for fixing the housing 1, a lidar 11 for environmental perception and navigation, a drive wheel set 12 for large-scale movement, and a parking mechanism 15 for lifting and fixing. The frame 9 is welded from square tubing and provides a mounting base for the housing mounting bracket 10, lidar 11, drive wheel set 12, parking mechanism 15, single-degree-of-freedom lifting platform 6, and electronic control module. The electronic control module includes a battery 13, a parking mechanism control module 14, a mobile platform controller 16, a single-degree-of-freedom lifting platform control module 17, a parking mechanism remote control module 18, a wheel set motor driver 19, a six-degree-of-freedom attitude adjustment platform controller 20, a single-degree-of-freedom lifting platform remote control module 21, and a central controller 22. The installation positions of the components are as follows: the outer shell mounting bracket 10 is bolted to the edge of the frame 9, the drive wheel set 12 and the parking mechanism 15 are bolted to the bottom of the frame 9, the lidar 11 and the single-degree-of-freedom lifting platform 6 are bolted to the top of the frame 9, and the various modules of the electronic control module are bolted to the inside of the frame 9.

[0051] The internal control process is as follows: The central controller 22 receives environmental perception data from the lidar 11 to build a map, performs global motion planning based on the target task, and generates instructions.

[0052] For large-scale transportation, the central controller 22 sends instructions to the mobile platform controller 16, which then instructs the wheel set motor driver 19 to convert the instructions into motor drive signals, thereby driving the wheel set 12 to move.

[0053] Upon reaching the target workstation, the central controller 22 sends instructions to the parking mechanism control module 14, which converts these instructions into motor drive signals to drive the parking mechanism 15 to perform a lifting operation and fix the robot in place.

[0054] For large-scale vertical movement, the central controller 22 sends instructions to the single-degree-of-freedom lifting platform control module 17, which converts them into motor drive signals to drive the single-degree-of-freedom lifting platform 6 to move.

[0055] For high-precision assembly, a binocular camera 30 measures the relative pose of the workpiece 4 and the target to be assembled, and sends the data to the central controller 22. After processing the visual data, the central controller 22 generates motion commands for the six-degree-of-freedom (DOF) attitude adjustment platform and sends them to the six-DOF attitude adjustment platform controller 20. The six-DOF attitude adjustment platform controller 20 converts the commands into motor drive signals and sends them to the first branch servo motor 39 and the second branch servo motor 48 to drive the six-DOF attitude adjustment platform 5 to perform precise attitude adjustment.

[0056] In addition, battery 13 provides power to the entire robot system. The parking mechanism remote control module 18 and the single-degree-of-freedom lifting platform remote control module 21 are used to manually control the parking mechanism 15 and the single-degree-of-freedom lifting platform 6, respectively.

[0057] like Figure 3 The diagram shows the structure of the single-degree-of-freedom lifting platform 6 of the present invention. The single-degree-of-freedom lifting platform 6 consists of a single-degree-of-freedom lifting platform frame 23 and an electric push rod 24. The bottom of the single-degree-of-freedom lifting platform frame 23 is connected to the vehicle frame 9 by bolts, and the top is used to fix the six-degree-of-freedom attitude adjustment platform 5. The electric push rod 24 is used to drive the single-degree-of-freedom lifting platform 6 to move vertically.

[0058] like Figure 4 The diagram shows the structure of the six-DOF attitude adjustment platform 5 of the present invention. The six-DOF attitude adjustment platform 5 consists of a moving platform 25, a first branch 26, a second branch 27, a third branch 28, and a stationary platform 29. The stationary platform 29 provides the mounting base for the three branches and the binocular camera 30. The moving platform 25 is used to support the workpiece support 3 and realize end-effector pose output.

[0059] like Figure 5 The diagram shows the structure of the drive wheel assembly 12 of the present invention. The drive wheel assembly 12 includes a wheel assembly servo motor 31, a planetary reducer 32, a shock absorption module 33, a wheel assembly bracket 34, and Mecanum wheels 35. The wheel assembly servo motor 31 provides power for the movement of the mobile platform; the planetary reducer 32 increases the output torque; the shock absorption module 33 buffers ground impacts; and the Mecanum wheels 35 enable omnidirectional movement of the mobile platform. All components are connected sequentially by bolts, and finally, the wheel assembly bracket 34 is bolted to the frame 9.

[0060] like Figure 6 The diagram shown is a structural schematic of a single branch of the six-DOF attitude adjustment platform of this invention. This branch achieves two translational degrees of freedom through the coordinated motion of the electric cylinder and the linear module.

[0061] like Figure 7 The diagram shown is a structural schematic of the ball joint 36 of the present invention, which consists of a ball joint seat 51, a ball sleeve 52 and a ball head 53.

[0062] like Figure 8 The diagram shown illustrates the assembly of two robots in this invention. The collaborative method of the dual-robot cooperative redundant degree-of-freedom mobile parallel composite robot includes the following steps: ① The task is distributed to multiple robots, and the master and slave roles are confirmed; ② Each robot navigates globally to the designated proximity position; ③ Perform coarse adjustment confirmation and movable domain verification; ④ The slave unit enters the parking preparation stage and performs parking lifting and fixing; ⑤ The main unit undergoes fine-tuning; ⑥ The main unit will perform parking, lifting, and fixing as needed; ⑦ Perform precise alignment under visual guidance; ⑧ Perform approach and judgment based on displacement / pose; ⑨ Once docking is confirmed, proceed with the assembly process; ⑩ Release the parking status and reset the device to complete the task.

[0063] Specifically, see below. Figure 8 , Figure 9 This invention provides a detailed description of the collaborative method for a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot. In this embodiment, the central controller 22 has a pre-installed complete control program that executes the dual-machine cooperative docking according to the following steps S1-S4: S1: Visual Recognition and Coordinate System Transformation like Figure 8 As shown, the robot host is fixed in the designated position, and the robot slave is placed in the position opposite to the robot host, thus determining the roles of the robot host and the robot slave; The robot host's binocular camera 30 acquires images of the robot end workpiece 4 of the opposing robot slave. The robot host's central controller 22 preprocesses the images, uses an ellipse edge enhancement detection algorithm to identify the circular features of the workpiece end face, fits an ellipse and extracts the coordinates of the ellipse center point in the pixel coordinate system and the major and minor axis parameters of the ellipse. Based on the intrinsic parameters and depth information of the binocular camera 30 of the robot host, the pixel coordinates of the center point of the ellipse are converted into three-dimensional coordinates in the camera coordinate system. Based on the preset rotation and translation matrices between the camera coordinate system and the static platform coordinate system, the three-dimensional coordinates in the camera coordinate system are converted into three-dimensional pose data in the static platform coordinate system with the static platform 29 of the robot host as the reference. At the same time, the normal attitude angle of the workpiece end face is calculated according to the major axis direction of the ellipse. Specifically, a binocular camera 30 is fixed on the static platform 29 of the robot host for acquiring images of the workpiece 4 at the end effector of the opposing robot slave. The central controller 22 of the robot host receives the RGB images and depth images acquired by the binocular camera 30 and performs the following processing: First, the RGB image is preprocessed, including Gaussian filtering for noise reduction and grayscale conversion, to reduce ambient light interference and image noise. Gaussian filtering uses a 3×3 convolution kernel, and weighted averaging smooths the image, making edges clearer. Then, an elliptical edge enhancement detection algorithm is used to identify the circular features of the workpiece end face. The specific steps are as follows: ① Edge detection: The central controller uses the Canny operator to extract image edges, sets a low threshold of 50 and a high threshold of 150, and obtains a binarized edge image; ② Contour extraction: Perform contour search on the edge image and filter out contours containing at least 5 points.

[0064] ③ Circularity calculation: Calculate the approximate circularity of each contour. The formula for circularity is: ,in For the outline area, This is the perimeter of the outline. Outlines with a roundness greater than 0.7 are retained. ④ Ellipse Fitting: The filtered contours are fitted with an ellipse using the least squares method to obtain the ellipse equation parameters, and the coordinates of the ellipse center point in the pixel coordinate system are extracted. and the length of the major axis of the ellipse and minor axis length The objective function for ellipse fitting is to minimize the algebraic distance: , Next, by combining the depth information from the binocular camera 30, the depth value corresponding to the center point of the ellipse is obtained. According to camera internal parameters Based on the principle of pinhole imaging, pixel coordinates are converted into three-dimensional coordinates in the camera coordinate system. : , Since the binocular camera 30 is fixedly mounted on the static platform 29 and tilted at a preset angle (ranging from 30° to 60°, and 45° in this embodiment), it is necessary to convert the coordinates in the camera coordinate system to coordinates in the static platform coordinate system based on the static platform 29. The conversion relationship between the camera coordinate system and the static platform coordinate system is obtained through calibration, including the rotation matrix. Translation matrix : , In this embodiment, the camera coordinate system needs to be rotated 45° around the X-axis and then 90° around the Z-axis to be parallel to the axes of the static platform coordinate system. Therefore, the rotation matrix is: , The translation matrix is ​​obtained by measuring the position of the camera's optical center in the static platform coordinate system, and in this embodiment it is: , Therefore, the complete coordinate transformation formula is: , Simultaneously, based on the direction of the major axis of the ellipse, the normal attitude angle of the workpiece end face can be calculated. Specifically, with the center of the ellipse as the origin and the direction of the minor axis as... The axis, with the major axis in the direction of The direction of the shaft with its vertical end facing outwards is... Establish the end face coordinate system. The angle between the optical axis and the camera's optical axis is called the yaw angle. , The angle between the axis and the horizontal plane is the pitch angle. By calculating the projection direction of the major axis of the ellipse onto the image plane and combining it with depth information, the three-dimensional direction of the end face normal vector can be obtained, and then the following can be calculated: and .

[0065] S2: Master-Slave Coordination and Parking The central controller 22 of the robot host calculates the relative pose error between the workpiece of the robot host and the workpiece of the opposing robot slave based on the converted pose data. If the relative pose error exceeds the joint compensation range of the robot host's six-degree-of-freedom pose adjustment platform 5 and single-degree-of-freedom lifting platform 6, the robot host's central controller 22 sends a correction command to the planar moving platform 2, driving the drive wheel set 12 to make a slight movement until the relative pose error enters the compensation range. After the rough adjustment is completed, the central controller 22 of the robot host negotiates with the opposing robot slave via wireless communication to re-determine the roles of the robot host and the robot slave. Then, the robot slave executes the parking mechanism 15 to lift and rigidly fix the robot slave's frame 9 to the ground, while the robot host remains in a moving state.

[0066] Specifically, the central controller 22 calculates the relative pose error between the workpiece of the robot host and the workpiece of the opposing robot slave based on the pose data converted in step S1. .in, For positional deviation, This represents the attitude angle deviation.

[0067] The central controller 22 determines whether the error is within the combined compensable range of the six-degree-of-freedom attitude adjustment platform 5 and the single-degree-of-freedom lifting platform 6. The combined compensable range is determined by the travel limits of each branch and the lifting range of the lifting platform, and is pre-stored in the central controller 22. In this embodiment, the X and Y direction movement range of the six-degree-of-freedom attitude adjustment platform 5 is ±50mm, the Z direction movement range is ±30mm, and the attitude angle adjustment range is ±15°; the lifting range of the single-degree-of-freedom lifting platform 6 is 0-200mm.

[0068] like If the movement exceeds the compensable range, the central controller 22 sends a correction command to the mobile platform controller 16. The mobile platform controller 16 then drives the wheel assembly motor driver 19, causing the drive wheel assembly 12 to move slightly until... Entering the compensable range. Corrective movement employs a PID control algorithm, using the pose error from visual feedback as input, and outputting the wheel motor's speed and direction. This stage is only performed before stopping.

[0069] After the coarse adjustment is completed, the two robots exchange status information via a wireless communication link, including current position, drive wheel group status, parking mechanism status, and available adjustment range of the six-degree-of-freedom attitude adjustment platform and the single-degree-of-freedom lifting platform. They also determine the master and slave roles for this docking according to a predetermined strategy. In this embodiment, the robot carrying the binocular camera is designated as the master robot, and the other robot is designated as the slave robot.

[0070] After role confirmation, the slave robot executes the parking procedure: the central controller 22 sends a lifting command to the parking mechanism control module 14 of the slave robot, and the parking mechanism 15 lifts the frame 9, causing the drive wheel set 12 to leave the ground and establish a rigid constraint with the ground. The main robot remains movable to allow for possible subsequent fine-tuning. During the lifting process, the system continuously activates the collision monitoring and emergency stop switch 7 response channels to ensure safety.

[0071] S3: Visual Closed-Loop Fine-Tuning The robot slave's binocular camera 30 continuously acquires images at a set frequency, repeating step S1 to obtain real-time relative pose; The central controller 22 of the robot slave calls the pre-stored inverse kinematics model of the 3-PRPS parallel mechanism to solve the current relative pose error into the movement of the first linear joint and the extension of the second linear joint in each branch of the six-degree-of-freedom pose adjustment platform 5. According to the master-slave collaboration strategy, the central controller 22 of the robot slave assigns and adjusts tasks: the robot master undertakes the main position and posture compensation, and the robot slave performs minor compensation within its own controllable range; the central controller 22 of the robot slave generates corresponding control commands to drive the first servo motor 39 and the second servo motor 48 of each branch, so that the moving platform 25 drives the workpiece 4 to gradually approach the target posture. During the adjustment process, if large-scale compensation in the vertical direction is required, the central controller 22 of the robot slave simultaneously sends instructions to the electric push rod 24 of the single-degree-of-freedom lifting platform 6 to complete the lifting compensation in a coordinated manner.

[0072] Specifically, after parking is completed, the system enters the fine-tuning stage guided by high-precision vision. At this time, the drive wheel assembly 12 is locked, and only the six-degree-of-freedom attitude adjustment platform 5 and the single-degree-of-freedom lifting platform 6 are allowed to perform position / attitude adjustments.

[0073] The binocular camera 30 continuously acquires images at a frequency of 30Hz, with the frequency range selectable between 30 and 120Hz. It repeats the visual recognition and coordinate system transformation process of S1 to obtain real-time relative pose. .

[0074] Central controller 22 calculates real-time pose and target pose Error between .

[0075] The central controller 22 calls the pre-stored inverse kinematics model of the 3-PRPS parallel mechanism, and... The calculation is performed on the driving quantities of each branch of the six-degree-of-freedom attitude adjustment platform.

[0076] The central controller 22 allocates and adjusts tasks according to a master-slave collaborative strategy: the master host undertakes the main pose compensation, that is, according to... The drive quantity of the slave device is directly calculated; after receiving the coordination command from the master device, the slave device performs minor compensation to avoid motion conflicts. The specific compensation amount is calculated in real time by the central controller 22 based on the current pose and workspace margin of both devices. For example, when the movement in the X direction is large, the master and slave devices can share the movement proportionally, or the master device can complete most of the movement, and the slave device can only perform follow compensation.

[0077] The central controller 22 converts the calculated drive quantity into control commands and sends them to the six-degree-of-freedom attitude adjustment platform controller 20 and the single-degree-of-freedom lifting platform control module 17. The six-degree-of-freedom attitude adjustment platform controller 20 calculates the pulse count or position loop setpoint for each servo motor based on the drive quantity and sends it via EtherCAT bus to the first servo motor 39 and the second servo motor 48 of each branch, thereby realizing the extension and retraction of the electric cylinder telescopic rod 37 and the translation of the slider 47. The single-degree-of-freedom lifting platform control module 17 drives the electric push rod 24 to achieve vertical lifting compensation.

[0078] During the adjustment process, visual feedback forms a closed-loop control: after each adjustment, the binocular camera 30 remeasures the pose, the central controller 22 recalculates the error and generates the next round of instructions, until the error is less than the preset fine-tuning tolerance. In this embodiment, the fine-tuning tolerance is set to position error ≤ 0.5mm and attitude angle error ≤ 0.1°.

[0079] S4: Docking Completed and Reset When the real-time relative pose error is less than the preset docking tolerance, the central controller 22 of the robot slave executes the final docking action, and the control platform 25 of the robot slave moves along the docking direction until the workpiece 4 contacts or is inserted into the workpiece of the opposing robot host. After docking is completed, the robot host's binocular camera 30 rechecks the pose. Once it is confirmed to be correct, the robot host's central controller 22 sends out a completion signal. The robot host's parking mechanism 15 is released from lifting, and each platform returns to its initial position, thus ending the mission.

[0080] Specifically, when the real-time relative pose error is less than the preset final docking tolerance (in this embodiment, the position error is set to ≤0.2mm and the attitude angle error to ≤0.05°), the central controller 22 determines that the docking conditions have been met and executes the final docking action. The central controller 22 generates a movement command along the docking direction (in this embodiment, the docking direction is the X-axis direction), controlling the moving platform 25 to move the workpiece 4 forward at a slow speed of 1mm / s until the workpiece 4 contacts the opposing workpiece or inserts to a predetermined depth. During the movement, the binocular camera 30 continuously monitors the relative pose. Once the pose deviation is detected to exceed the safety threshold (e.g., position deviation >0.5mm), the movement is immediately stopped and readjusted. After docking is completed, the binocular camera 30 acquires images again to verify whether the final pose meets the requirements. After confirmation, the central controller 22 sends a docking completion signal to the slave device via wireless communication. The central controller 22 sends a recovery command to the parking mechanism control module 14, the parking mechanism 15 releases its lifting action, and the drive wheel set 12 returns to contact with the ground. The central controller 22 controls the six-degree-of-freedom attitude adjustment platform 5 and the single-degree-of-freedom lifting platform 6 to return to the safe initial pose. If the center point of the moving platform returns to the (0,0,370) position, the driving quantities of each branch are reduced to zero, the temporary data of this docking task is cleared, and the system enters standby mode or accepts the next task.

[0081] The present invention includes fault tolerance, anomaly handling, and security measures. In each of the above steps, the central controller 22 monitors the system status in real time and performs the following anomaly handling: ① Safety boundary and emergency stop protection: In any step, once the emergency stop switch 7 is triggered or the sensor detects a danger, such as the lidar 11 detecting an obstacle entering the safety area, the central controller 22 immediately cuts off all motor drive signals, the system immediately executes the stop strategy and enters the safe stop state.

[0082] ②Over-limit protection, i.e.: retraction beyond the compensable range. During coarse or fine adjustment, if the relative pose is found to exceed the compensable range of the parallel / lifting mechanism, for example, if the requested movement exceeds the travel limit of the six-DOF attitude adjustment platform 5 or the single-DOF lifting platform 6, the central controller 22 stops the current stage of action and instructs the mobile platform controller 16 to perform limited planar movement again, which is only allowed before parking, or prompts manual intervention.

[0083] ③ Handling Communication Anomalies: When wireless communication fails, both parties should revert to a pre-defined security strategy or enter a waiting and retry state, and should not engage in high-risk contact actions when communication is unreliable; if necessary, they can switch to manual remote control mode. For example, if the wireless communication interruption exceeds a set time (500ms in this embodiment), both robots will stop moving according to a pre-defined strategy and enter a waiting reconnection state until communication is restored.

[0084] ④ Manual / Remote Intervention Interface: The parking mechanism remote control module 18 and the single-degree-of-freedom lifting platform remote control module 21 retain a manual control channel, allowing operators to directly control the parking and lifting actions via remote control in emergency or special circumstances.

[0085] Compared to existing mobile robotic arms or composite robots on the market, which are typically combinations of mobile platforms and serial robotic arms, the technical solution of "mobile platform + single-degree-of-freedom lifting platform + six-degree-of-freedom attitude adjustment platform" adopted in this invention has significant advantages in realizing the transfer and high-precision assembly of heavy-load workpieces, specifically reflected in: ① The high load-bearing capacity and load distribution advantages are achieved through the collaborative efforts of the planar mobile platform 2, the single-degree-of-freedom lifting platform 6, and the six-degree-of-freedom attitude adjustment platform 5. The single-degree-of-freedom lifting platform 6, namely the single-degree-of-freedom lifting platform frame 23 + electric push rod 24, bears most of the static load for vertical support and vertical movement, preventing the six-degree-of-freedom attitude adjustment platform 5 from bearing the entire weight, thereby reducing the structural size and drive power requirements of the six-degree-of-freedom attitude adjustment platform. The frame 9 and drive wheel set 12 of the planar mobile platform 2 bear the overall horizontal displacement load. The drive wheel set, namely the wheel set servo motor 31, planetary reducer 32, Mecanum wheel 35, works in conjunction with the shock absorption module 33 to ensure stable load bearing and buffering during movement, reducing dynamic impact on the six-degree-of-freedom attitude adjustment platform. The system can achieve a greater overall load-bearing capacity and more even load distribution than the traditional mobile platform + serial robotic arm, making it suitable for heavy-duty transport and assembly scenarios.

[0086] ②The high rigidity and high precision of the assembly capability are determined by the structure of the six-degree-of-freedom attitude adjustment platform 5.

[0087] The six-degree-of-freedom (DOF) attitude adjustment platform 5 adopts a three-branch structure, namely: the first branch 26, the second branch 27, and the third branch 28 are driven in parallel. The moving platform 25 is used for end-effector attitude output, possessing the inherent high rigidity and high load-bearing accuracy of the parallel structure. The internal components of the branches include ball joints 36 (ball joint seat 51, ball sleeve 52, ball head 53), electric cylinders (electric cylinder telescopic rod 37, electric cylinder body 38), lead screws 44, and linear modules of guide rails 45, all high-rigidity transmission elements. This enables low deformation and high repeatability positioning accuracy, making it suitable for precision assembly. Compared to the flexibility, cumulative error, and backlash that easily occur in serial robotic arms when bearing large masses, the six-DOF attitude adjustment platform of this invention maintains high positioning rigidity and stability even under heavy loads.

[0088] ③ The decoupled motion division improves control and safety, which is achieved by the electronic control module and the central controller 22.

[0089] The central controller 22 fuses data from the lidar 11 and the binocular camera 30 for global navigation, workpiece pose recognition, and motion planning for the six-degree-of-freedom (DOF) attitude adjustment platform. Each functional module—the mobile platform controller 16, the six-DOF attitude adjustment platform controller 20, and the single-DOF lifting platform control module 17—is responsible for the robot's motion control, achieving a hierarchical control architecture. The parking mechanism 15 and its control modules—the parking mechanism control module 14 and the parking mechanism remote control module 18—ensure reliable fixation of the robot to the ground upon arrival at its designated position, reducing micro-disturbances during assembly and thus improving assembly accuracy and operational safety. Through hierarchical hardware and software control, the system can simultaneously meet the needs of large-scale transfer and high-precision end-effector assembly.

[0090] ④ Flexible space and adaptability are provided by the collaborative efforts of a mobile platform, a single-degree-of-freedom lifting platform, and a six-degree-of-freedom attitude adjustment platform.

[0091] The planar moving platform enables a wide range of planar movement, the single-degree-of-freedom lifting platform provides a wide range of vertical travel, and the six-degree-of-freedom attitude adjustment platform provides precise attitude adjustment and micro-displacement. The combination of these three components allows the system to cover a larger workspace and achieve a wider range of pick-up, placement, and assembly position adjustment capabilities.

[0092] The design of workpiece support 3 and replaceable workpiece 4 supports quick clamping and adaptation of workpieces of different sizes / models, improving the flexibility of on-site line changeover and deployment.

[0093] ⑤ Dynamic response and stability are achieved through the combination of wheel set damping module and servo drive.

[0094] The shock absorption module 33 and the planetary reducer 32 with reduction ratio in the wheel set can effectively buffer the vibration and impact during movement, and reduce the disturbance transmitted to the six-degree-of-freedom attitude adjustment platform and the workpiece.

[0095] The six-degree-of-freedom attitude adjustment platform, consisting of a branch first servo motor 39, a branch second servo motor 48, a first synchronous belt module 40 / second synchronous belt module 50, and a linear module combination, has a fast response and high load driving capability, making it suitable for assembly tasks that require rapid attitude switching.

[0096] ⑥ Enhanced structural safety and stable installation are achieved through a combination of mechanical connection methods and multiple fixing mechanisms.

[0097] All major components, namely the single-degree-of-freedom lifting platform 6, the six-degree-of-freedom attitude adjustment platform 5, and the electrical control module, are installed using bolt connections, facilitating on-site maintenance, replacement, and reliable fixation. The parking mechanism 15 enables the lifting mechanism to be fixed to the ground, improving its resistance to disturbances and enhancing safety during assembly. The arrangement of the emergency stop switch 7 and the start / stop switch 8 enhances the system's safe handling capabilities in emergency situations.

[0098] ⑦ Maintenance and modular advantages The system is modular, consisting of a planar motion platform, a single-degree-of-freedom lifting platform, a six-degree-of-freedom attitude adjustment platform, and industrial control and sensing modules. This facilitates separation, inspection, and replacement, reducing maintenance costs and improving availability. The repetitive design of the branch structure of the six-degree-of-freedom attitude adjustment platform, i.e., the same branches, is beneficial for component interchangeability and manufacturing efficiency.

[0099] In summary, this invention physically decouples the load-bearing, displacement, and precise positioning functions in the mechanical structure. Specifically, the mobile platform is responsible for displacement, the single-degree-of-freedom lifting platform is responsible for vertical load-bearing, and the six-degree-of-freedom attitude adjustment platform is responsible for precise positioning. With the assistance of layered control and multi-sensor perception, it achieves the difficult task of balancing heavy load handling and high-precision assembly. Its overall performance is superior to common mobile serial robotic arms or simple mobile platform + serial arm solutions. It is especially suitable for industrial scenarios involving heavy component assembly, high assembly precision requirements, and long-distance transportation.

Claims

1. A collaborative method for a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot, characterized in that, Includes the following steps: S1: Visual Recognition and Coordinate System Transformation Fix the robot host in the designated position, and place the robot slave in the position opposite to the robot host to determine the roles of the robot host and the robot slave. The binocular camera (30) of the robot host acquires images of the robot end workpiece (4) of the opposing robot slave. The central controller (22) of the robot host preprocesses the images, uses the ellipse edge enhancement detection algorithm to identify the circular features of the workpiece end face, fits the ellipse and extracts the coordinates of the center point of the ellipse in the pixel coordinate system and the major axis and minor axis parameters of the ellipse. The specific steps are as follows: ① Edge detection: The central controller uses the Canny operator to extract image edges, sets a low threshold of 50 and a high threshold of 150, and obtains a binarized edge image; ② Contour extraction: Perform contour search on the edge image and filter out contours containing at least 5 points; ③ Circularity calculation: Calculate the approximate circularity of each contour. The formula for circularity is: ,in For the outline area, The perimeter of the outline is defined; outlines with a roundness greater than 0.7 are retained. ④ Ellipse Fitting: The filtered contours are fitted with an ellipse using the least squares method to obtain the ellipse equation parameters, and the coordinates of the ellipse center point in the pixel coordinate system are extracted. and the length of the major axis of the ellipse and minor axis length The objective function for ellipse fitting is to minimize the algebraic distance. ， Next, by combining the depth information from the binocular camera (30), the depth value corresponding to the center point of the ellipse is obtained. According to camera internal parameters Based on the principle of pinhole imaging, pixel coordinates are converted into three-dimensional coordinates in the camera coordinate system. : ， The binocular camera (30) is fixedly mounted on the static platform (29) at a preset tilt angle, which is between 30° and 60°. The coordinates in the camera coordinate system are converted to coordinates in the static platform coordinate system based on the static platform (29). The transformation relationship between the camera coordinate system and the static platform coordinate system is obtained through calibration, including the rotation matrix. Translation matrix : ， At the same time, the normal attitude angle of the workpiece end face is calculated based on the direction of the major axis of the ellipse; Specifically, as follows: with the center of the ellipse as the origin, and the direction of the minor axis as... The axis, with the major axis in the direction of The direction of the shaft with its vertical end facing outwards is... Establish the end face coordinate system based on the axis. The angle between the optical axis and the camera's optical axis is called the yaw angle. , The angle between the axis and the horizontal plane is the pitch angle. By calculating the projection direction of the major axis of the ellipse onto the image plane and combining it with depth information, the three-dimensional direction of the end face normal vector is obtained, and then the following can be calculated: and ; S2: Master-Slave Coordination and Parking The central controller (22) of the robot host calculates the relative pose error between the robot host and the opposing robot slave based on the converted pose data; After the rough adjustment is completed, the central controller (22) of the robot host negotiates with the opposing robot slave through wireless communication to re-determine the roles of the robot host and the robot slave. Then the robot slave executes the parking mechanism (15) to lift up and rigidly fix the robot slave's frame (9) to the ground, while the robot host remains in a moving state. The specific steps are as follows: ①The central controller (22) calculates the relative pose error between the workpiece of the robot host and the workpiece of the opposing robot slave based on the pose data converted by S1: ;in, For positional deviation, This refers to the attitude angle deviation; ② The central controller (22) determines whether the error is within the joint compensation range of the six-degree-of-freedom attitude adjustment platform (5) and the single-degree-of-freedom lifting platform (6); the joint compensation range is determined by the travel limit of each branch and the lifting range of the lifting platform, and is stored in the central controller 22 in advance. like If the compensation range is exceeded, the central controller (22) sends a correction command to the mobile platform controller (16), and the mobile platform controller (16) drives the wheel set motor driver (19) to make the drive wheel set (12) move slightly until... Entering the compensation range; the correction movement adopts a PID control algorithm, using the pose error of visual feedback as input, and outputting the speed and direction of the wheel set motor; this stage is only executed before parking; ③ After the coarse adjustment is completed, the two machines exchange status information through the wireless communication link, including the current position, the status of the drive wheel group, the status of the parking mechanism, the adjustment range of the six-degree-of-freedom attitude adjustment platform and the single-degree-of-freedom lifting platform, and determine the roles of the master and slave machines in this docking according to the predetermined strategy. After the role is confirmed, the slave robot executes the parking procedure: the central controller (22) sends a lifting command to the parking mechanism control module (14) of the slave robot, the parking mechanism (15) lifts the frame (9) so that the drive wheel set (12) leaves the ground and establishes a rigid constraint with the ground; the main robot remains in motion. S3: Visual Closed-Loop Fine-Tuning The robot slave's binocular camera (30) continuously acquires images at a set frequency, repeats S1, and obtains real-time relative pose; The robot slave's central controller (22) calls the pre-stored 3-PRPS parallel mechanism inverse kinematics model to solve the current relative pose error into the movement of the first linear joint and the extension of the second linear joint in each branch of the six-degree-of-freedom pose adjustment platform (5). The specific steps are as follows: ① After parking is completed, the system enters the fine posture adjustment stage guided by high precision vision; at this time, the drive wheel group (12) is locked, and only the six-degree-of-freedom posture adjustment platform (5) and the single-degree-of-freedom lifting platform (6) are allowed to perform position / attitude adjustment; The binocular camera (30) continuously acquires images at a set frequency value, with the frequency range selected between 30 and 120 Hz; the visual recognition and coordinate system transformation process of S1 is repeated to obtain the real-time relative pose. ; ②The central controller (22) calculates the real-time pose and the target pose. Error between ; The central controller (22) calls the pre-stored inverse kinematics model of the 3-PRPS parallel mechanism and performs... The driving quantities of each branch of the six-degree-of-freedom attitude adjustment platform (5) are calculated. The central controller (22) allocates and adjusts tasks according to the master-slave collaborative strategy: the master undertakes the main pose compensation, that is, according to The drive quantity of the machine is directly calculated; after receiving the coordination instruction from the master, the slave machine performs micro-compensation; the specific compensation amount is calculated in real time by the central controller (22) based on the current pose and workspace margin of the two machines. ③ The central controller (22) converts the calculated driving quantity into control commands and sends them to the six-degree-of-freedom attitude adjustment platform controller (20) and the single-degree-of-freedom lifting platform control module (17); the six-degree-of-freedom attitude adjustment platform controller (20) calculates the number of pulses or position loop setpoints of each servo motor according to the driving quantity, and sends them to the first servo motor (39) and the second servo motor (48) of each branch through the EtherCAT bus to realize the extension and retraction of the electric cylinder telescopic rod (37) and the translation of the slider (47); the single-degree-of-freedom lifting platform control module (17) drives the electric push rod (24) to realize vertical lifting compensation; During the adjustment process, visual feedback forms a closed-loop control: after each adjustment is completed, the binocular camera (30) remeasures the pose, the central controller (22) recalculates the error and generates the next round of instructions until the error is less than the preset fine-tuning tolerance; S4: Docking Completed and Reset When the real-time relative pose error is less than the preset docking tolerance, the central controller (22) of the robot slave executes the final docking action, and the control platform (25) of the robot slave moves along the docking direction until the workpiece (4) contacts or is inserted into the workpiece of the opposing robot host. After docking is completed, the binocular camera (30) of the robot host verifies the pose again. After confirming that there are no errors, the central controller (22) of the robot host sends out a completion signal. The robot host's parking mechanism (15) is released from lifting, each platform is reset to its initial position, and the task ends; The specific steps are as follows: ① When the real-time relative pose error is less than the preset final docking tolerance, the central controller (22) determines that the docking conditions have been met and executes the final docking action; the central controller (22) generates a movement command along the docking direction and controls the moving platform (25) to drive the workpiece (4) to move slowly forward until the workpiece (4) contacts the opposite workpiece or inserts into the predetermined depth. During the movement, the binocular camera (30) continuously monitors the relative pose. Once the pose deviation is detected to exceed the safety threshold, such as a position deviation > 0.5 mm, the movement is immediately stopped and readjusted. ② After docking is completed, the binocular camera (30) acquires images again to verify whether the final pose meets the requirements; after confirming that there are no errors, the central controller (22) sends a docking completion signal to the slave device through wireless communication; ③ The central controller (22) sends a recovery command to the parking mechanism control module (14), the parking mechanism (15) releases the lifting, and the drive wheel set (12) resumes contact with the ground; The central controller (22) controls the six-degree-of-freedom attitude adjustment platform (5) and the single-degree-of-freedom lifting platform (6) to return to the safe initial pose; the driving quantities of each branch are returned to zero, the temporary data of this docking task is cleared, and the system enters standby mode or accepts the next task.

2. The cooperative method for a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot according to claim 1, characterized in that: In S1, the pixel coordinates of the center point of the ellipse are converted into three-dimensional coordinates in the camera coordinate system based on the intrinsic parameters and depth information of the binocular camera (30) of the robot host.

3. The cooperative method for a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot according to claim 1, characterized in that: In S1, based on the preset rotation and translation matrix between the camera coordinate system and the static platform coordinate system, the three-dimensional coordinates in the camera coordinate system are converted into three-dimensional pose data in the static platform coordinate system with the static platform (29) of the robot host as the reference. At the same time, the normal attitude angle of the workpiece end face is calculated according to the major axis direction of the ellipse.

4. The cooperative method for a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot according to claim 1, characterized in that: In S2, if the relative pose error exceeds the joint compensation range of the six-degree-of-freedom posture adjustment platform (5) and the single-degree-of-freedom lifting platform (6) of the robot host, the central controller (22) of the robot host sends a correction command to the planar moving platform (2) to drive the drive wheel group (12) to make a slight movement until the relative pose error enters the compensation range.

5. The cooperative method for a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot according to claim 1, characterized in that: In the S3, according to the master-slave collaboration strategy, the central controller (22) of the robot slave assigns adjustment tasks: the robot master undertakes the main position and posture compensation, and the robot slave performs micro-compensation within its own controllable range; the central controller (22) of the robot slave generates corresponding control commands to drive the first servo motor (39) and the second servo motor (48) of each branch, so that the moving platform (25) drives the workpiece (4) to gradually approach the target pose.

6. The cooperative method for a dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot according to claim 1, characterized in that: In S3, if large-scale vertical compensation is required during the adjustment process, the central controller (22) of the robot slave simultaneously sends instructions to the electric push rod (24) of the single-degree-of-freedom lifting platform (6) to complete the lifting compensation in coordination.

7. A dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot that implements the cooperative method of any one of claims 1-6, characterized in that: The system includes a planar moving platform (2) for omnidirectional movement, a single-degree-of-freedom lifting platform (6) is installed on the top of the planar moving platform (2), a six-degree-of-freedom attitude adjustment platform (5) is installed at the lifting output end of the single-degree-of-freedom lifting platform (6), the output end of the six-degree-of-freedom attitude adjustment platform (5) is a moving platform (25) for adjusting the posture in six degrees, and a workpiece support (3) for carrying the workpiece (4) is installed on the moving platform (25). The six-degree-of-freedom attitude adjustment platform (5) includes a static platform (29) fixed to the single-degree-of-freedom lifting platform (6), and a binocular camera (30) for acquiring relative pose information of the docking workpiece is fixed on the static platform (29). The planar moving platform (2) is equipped with a central controller (22), which is electrically connected to the binocular camera (30), the drive wheel group (12) of the planar moving platform (2), the electric push rod (24) of the single-degree-of-freedom lifting platform (6), and the drive motors of the six-degree-of-freedom attitude adjustment platform (5). The central controller (22) is configured as follows: The image acquired by the binocular camera (30) is received, the end face features of the workpiece (4) of the opposing robot end are identified, and the three-dimensional pose of the workpiece relative to the local static platform (29) is calculated based on the preset coordinate system transformation relationship. Based on the calculated pose error, combined with the pre-stored inverse kinematics model of the six-degree-of-freedom pose adjustment platform (5), control commands for each branch drive motor are generated. According to the master-slave collaboration strategy, it communicates with the machine and the slave robot to control the planar moving platform (2), the single-degree-of-freedom lifting platform (6) and the six-degree-of-freedom posture adjustment platform (5) of the machine and the slave robot to perform coarse adjustment, pause, fine adjustment and docking actions in stages, so as to realize the dual-machine collaborative assembly. The six-degree-of-freedom attitude adjustment platform (5) includes three identical first branches (26), second branches (27) and third branches (28). The bottom of each branch is arranged in a triangular enclosure on the static platform (29) through a first straight joint, and the top of each branch is connected to the moving platform (25) through a ball joint (36). Each branch includes a first linear joint, a revolute joint, a second linear joint and a ball joint (36) connected in sequence. The translation output end of the first linear joint is connected to the revolute joint, the rotation output end of the revolute joint is connected to the second linear joint, and the output end of the second linear joint is equipped with a ball joint (36). The first linear pair is a guide rail lead screw linear module, including a guide rail seat (43), a lead screw (44) and a slider (47). The slider (47) is driven by a branch second servo motor (48) through a second synchronous belt module (50). The second linear pair is an electric cylinder, including an electric cylinder body (38) and an electric cylinder telescopic rod (37), wherein the electric cylinder telescopic rod (37) is driven by a branch first servo motor (39) through a first synchronous belt module (40); The rotating pair includes a rotating pair module (41) and a rotating pair seat (46). The rotating pair module (41) is installed on the upper end of the slider (47), and its rotation output end is fixedly connected to the cylinder body (38) of the electric cylinder. The ball joint (36) includes a ball head (53) connected to the electric cylinder telescopic rod (37) and a ball joint seat (51) connected to the moving platform (25), and a ball sleeve (52) is provided between the ball head (53) and the ball joint seat (51).

8. The dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot according to claim 7, characterized in that: The single-degree-of-freedom lifting platform (6) includes a single-degree-of-freedom lifting platform frame (23) and an electric push rod (24) installed therein. The telescopic end of the electric push rod (24) is fixedly connected to the static platform (29) of the six-degree-of-freedom attitude adjustment platform (5). The planar mobile platform (2) includes a frame (9), with a drive wheel set (12) and a parking mechanism (15) at the lower end of the frame (9), and a lidar (11) for environmental perception and navigation at the upper end of the frame (9). The drive wheel set (12) includes a wheel set servo motor (31), a planetary reducer (32) and a Mecanum wheel (35). The output end of the wheel set servo motor (31) is connected to the Mecanum wheel (35) via the planetary reducer (32). The planetary reducer (32) is provided with a shock absorption module (33) between the transmission seat and the frame (9).

9. The dual-machine cooperative redundant degree-of-freedom mobile parallel composite robot according to claim 7, characterized in that: The installation position of the binocular camera (30) satisfies that its optical axis is tilted at a preset angle to the plane of the static platform (29) so as to cover the field of view of the end workpiece (4) of the opposing robot. The central controller (22) is also connected to an emergency stop switch (7) and a start / stop switch (8), and is equipped with a wireless communication module for communicating with external systems.

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