Series-parallel conversion multi-arm gangue sorting system and control method thereof

Abstract

The present application relates to the technical field of sorting, and in particular to a series-parallel conversion multi-mechanical arm gangue sorting system and a control strategy thereof. The series-parallel conversion multi-mechanical arm gangue sorting system comprises a belt conveyor, a vibrating screening device, and a plurality of mechanical arm sorting devices arranged along the conveying direction of the belt conveyor. Each of the mechanical arm sorting devices comprises two multi-degree-of-freedom mechanical arms. The functional modes of the mechanical grippers on the mechanical arms can be divided into two modes: a grabbing mode and a pushing-off mode. A controller controls the two mechanical arms to independently perform sorting under series control or controls the two mechanical arms in the same mechanical arm sorting device to cooperatively perform sorting under parallel control. The sorting control strategy determines three sorting actions by judging the distribution position and particle size of the coal gangue. The present application is suitable for gangue sorting under complex working conditions through series-parallel conversion control, and improves the sorting efficiency and sorting accuracy.

Description

Technical Field

[0001] This invention relates to the field of sorting technology, and in particular to a multi-robotic arm gangue sorting system with series-parallel conversion and its control method. Background Technology

[0002] Existing robotic arm sorting devices for coal gangue mainly include truss type, series type and parallel type. The sorting methods of the end-effector are divided into gripping and separating. Through the cooperation between the robotic arm body and the end-effector, various forms of robotic arm sorting devices can be obtained. Each of them has its own advantages and disadvantages. In the series type, each individual robotic arm can freely achieve the gripping or separating of a single piece of gangue.

[0003] Faced with coal gangue of varying particle sizes that needs to be sorted, and with increasingly stringent sorting requirements, single serial or parallel robotic arms, as well as single gripping or separating sorting methods, are no longer sufficient. Serial single-arm sorting is difficult to handle gangue with larger particle sizes, while parallel robotic arms can sort gangue with cooperation, but consume a lot of power. Therefore, it is necessary to develop more versatile and flexible robotic arm sorting systems to handle complex and diverse application conditions and improve sorting efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the existing single serial or parallel robotic arm sorting devices are difficult to meet complex application conditions and have low sorting efficiency.

[0005] Therefore, the present invention provides a multi-robotic arm gangue sorting system and its control method with series-parallel conversion, so that the sorting system can be applied to gangue sorting under various complex working conditions to improve sorting efficiency and accuracy.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A multi-robotic arm gangue sorting system with serial-parallel conversion includes,

[0008] Belt conveyors, and

[0009] A vibrating screening device is installed at the feeding end of a belt conveyor and is used to screen out coal and gangue with a particle size greater than 200mm and transfer them to the belt conveyor.

[0010] The robotic arm sorting device includes multiple robotic arms arranged along the conveying direction of the belt conveyor. Each robotic arm sorting device includes two multi-degree-of-freedom robotic arms. The robotic arms are connected to robotic grippers for sorting gangue on the belt conveyor. The robotic grippers have two functional forms: gripping form and separating form.

[0011] The controller is used to operate the robotic arm to perform sorting actions. The controller can operate two robotic arms to perform sorting actions independently under series control or operate two robotic arms in the same robotic arm sorting device to perform sorting actions collaboratively under parallel control.

[0012] By adopting the above technical solutions, the robotic arm can independently grasp or separate gangue under serial control, which is highly flexible and free and easy to operate. However, when facing gangue with a large particle size, the robotic arm performs a grasping operation. Due to the large particle size and weight of the gangue, the power consumption of a single robotic arm is large and the damage to the robotic arm is greater. The gangue is easy to fall due to the unstable grasp of the robotic arm, which can easily damage the entire sorting device and cause the gangue to break and shatter. Parallel operation is complicated and cumbersome, and the sorting efficiency is low. When facing gangue with a small particle size, it is difficult to grasp the gangue in a coordinated manner. Therefore, both single serial and parallel robotic arms have the problem of low sorting efficiency when facing complex application scenarios. By employing a robotic gripper to perform grasping and separating actions, and in conjunction with a robotic arm to achieve series-parallel switching in gangue sorting, this system can effectively handle complex gangue sorting applications. Depending on the actual size of the gangue, the robotic arm can be controlled to switch between series and parallel modes. In series mode, a single robotic arm grasps or separates smaller-sized gangue, while in parallel mode, two robotic arms work together to sort the gangue. This effectively reduces the operating power of the robotic arms, improves the sorting accuracy and efficiency, and enables highly efficient sorting through a multi-robotic-arm sorting system.

[0013] Furthermore, the sorting action includes single-arm grasping under serial control, single-arm disengagement under serial control, and dual-arm collaborative grasping in the same robotic arm sorting device under parallel control.

[0014] Furthermore, it also includes a visual acquisition device, which is set between the vibrating screening device and the robotic arm sorting device. The visual acquisition device acquires images of coal and gangue on the belt conveyor through a binocular stereo camera, providing a basis for the controller to control the robotic arm sorting action.

[0015] Furthermore, the robotic arm is equipped with an industrial camera, which, together with the robotic arm, forms a hand-eye system for dynamically tracking the state of the gangue on the belt conveyor.

[0016] By adopting the above technical solution, using a binocular stereo camera in conjunction with a robotic arm hand-eye system, the identification and dynamic tracking of gangue can be achieved.

[0017] A multi-robotic arm gangue sorting control method with series-parallel conversion, including...

[0018] The distribution of gangue on the belt conveyor is determined by a visual acquisition device. First, the amount of coal between the gangue and the edge of the conveyor belt is determined.

[0019] If the amount of coal between the gangue and the edge of the conveyor belt is lower than the preset threshold, a single-arm separation method will be used for sorting.

[0020] If the amount of coal between the gangue and the edge of the conveyor belt is higher than the preset threshold, then a series and parallel sorting task is formulated according to the size of the gangue, and three sorting actions are implemented according to the distribution and size of the gangue.

[0021] By adopting the above technical solution, the distribution of the gangue to be sorted is judged, a suitable sorting task is formulated, and a suitable path is planned, thereby achieving fast and accurate sorting of gangue.

[0022] Furthermore, the serial-parallel sorting task is based on the KM algorithm. The KM algorithm is used to solve the optimal matching problem on the weighted bipartite graph composed of gangue in the robotic arm. The specific rules for solving the KM algorithm are as follows:

[0023] Rule 1: Each robotic arm can only perform one sorting task at a time;

[0024] Rule 2: Prevent collisions between two robotic arms working in the same sorting area;

[0025] Rule 3: Two robotic arms working in the same sorting area shall follow the series-parallel conversion control strategy;

[0026] Rule 4: The robotic arm prioritizes sorting gangue that is closest to it;

[0027] Rule 5: In the event of task overflow, prioritize the execution of large gangue sorting tasks;

[0028] Rule 6: When the robotic arm is performing its task, it should try not to damage the information of the gangue behind it;

[0029] Rule 7: Try to ensure that each robotic arm is performing a task.

[0030] Furthermore, after solving the problem using the KM algorithm, an improved RRT algorithm is used for path planning of the multiple robotic arms.

[0031] Furthermore, attraction and repulsion are introduced into the RRT algorithm.

[0032] By adopting the above technical solution, random nodes are guided to grow towards the target object by gravity, while repulsive force is used to limit the expansion of random nodes towards obstacles, thereby reducing the number of invalid nodes.

[0033] Furthermore, a hybrid curve trajectory is used to control the movement path of the robotic arm.

[0034] By adopting the above technical solution, the continuity of displacement, velocity and acceleration of the robotic gripper can be maintained during the movement of the gripper along the path.

[0035] The beneficial effects of this invention are as follows: It employs a binocular stereo camera in conjunction with a robotic arm hand-eye system to achieve the identification and dynamic tracking of gangue; it focuses on the robotic arm sorting device, designing a multi-functional robotic gripper capable of grasping and separating shapes, and cooperating with the robotic arm to achieve a series-parallel transformation sorting method for gangue. A series-parallel transformation control strategy is also formulated, effectively reducing the size and power of the robotic arm and improving the sorting accuracy and efficiency of gangue. To achieve efficient sorting in the multi-robotic arm sorting system, the KM algorithm is used to allocate tasks to the multi-robotic arm gangue groups to obtain the optimal task matching; then, an artificial potential field + RRT algorithm is used for path planning of the multi-robotic arms, introducing attraction and repulsion into the RRT algorithm to reduce the generation of invalid nodes and improve planning efficiency; and a hybrid curve trajectory is used to control the robotic arms to ensure the smoothness of movement; finally, a multi-robotic arm collaborative sorting control strategy is formulated to achieve fast and accurate sorting of gangue. The multi-robotic arm gangue sorting system based on series-parallel transformation can achieve rapid and accurate sorting of medium and large gangue, providing a new method for the application of robotic arms in the field of gangue sorting. Attached Figure Description

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] Figure 1 This is a schematic diagram of the structure of a multi-robotic arm gangue sorting system with series-parallel conversion in this invention.

[0038] Figure 2 This is a schematic diagram of the robotic arm sorting device in this invention.

[0039] Figure 3 This is a schematic diagram of the mechanical gripper in this invention.

[0040] Figure 4 This is a schematic diagram of the robotic arm sorting action in this invention.

[0041] Figure 5 This is a schematic diagram of the single-arm sorting action under serial control in this invention.

[0042] Figure 6 This is a schematic diagram of the parallel control of the dual-arm coordinated grasping and sorting action in this invention.

[0043] Figure 7 These are schematic diagrams illustrating different application scenarios in this invention.

[0044] Figure 8 This is a flowchart of a multi-robotic arm gangue sorting control method with series-parallel conversion according to the present invention.

[0045] Figure 9 This is a schematic diagram of a complex gangue sorting scenario in this invention.

[0046] Figure 10 This is a weighted bipartite graph representing the allocation of sorting tasks by the robotic arm in this invention.

[0047] Figure 11 This is a schematic diagram of the robotic arm sorting path planning in this invention.

[0048] Figure 12 This is a flowchart of the task allocation process in the serial-parallel sorting control method of this invention.

[0049] Figure 13 This is a flowchart of the sorting system in this invention under the control of a series-parallel sorting control strategy.

[0050] In the diagram: 1. Belt conveyor; 2. Vibrating screening device; 3. Vibration acquisition device; 4. Robotic arm sorting device; 40. First robotic arm sorting device; 400. Support frame; 401. Industrial camera; 402. Base; 403. Cylinder; 404. Servo motor; 405. Connecting shaft; 406. First connecting rod; 407. Second connecting rod; 408. Third connecting rod; 409. Fourth connecting rod; 410. Connecting bracket; 41. Second robotic arm sorting device; 5. Gangue bin. Detailed Implementation

[0051] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0052] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not 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 the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0053] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0054] Reference Figure 1 A multi-robotic arm gangue sorting system with series-parallel conversion includes a vibrating screening device 2, a belt conveyor 1, a vision acquisition device 3, a robotic arm sorting device 4, a gangue bin 5, a controller, and a sorting system control unit set in a host computer. The vibrating screening device 2 is set at the feeding end of the belt conveyor 1, and the gangue bin 5 is set on both sides of the belt conveyor 1 along the conveying direction of the belt conveyor 1.

[0055] The transmission direction of belt conveyor 1 is taken as the Z-axis, the width direction of belt conveyor 1 in the horizontal direction is taken as the X-axis, and the vertical direction is taken as the Y-axis.

[0056] The visual acquisition device 3 and the robotic arm sorting device 4 are sequentially mounted on the belt conveyor 1 along the Z-axis. At least two sets of robotic arm sorting devices 4 are provided, each set containing two multi-degree-of-freedom robotic arms. Multiple robotic arm sorting devices 4 are sequentially arranged along the Z-axis. In this embodiment, two robotic arm sorting devices 4 are provided: a first robotic arm sorting device 40 and a second robotic arm sorting device 41. The robotic arms in the first robotic arm sorting device 40 are robotic arms A1 and A2, and the robotic arms in the second robotic arm sorting device 41 are robotic arms B1 and B2. The two robotic arms in the same robotic arm sorting device are staggered along the Z-axis.

[0057] Vibrating screening device 2 is used to screen out particles larger than 200 mm and transfer them to belt conveyor 1. The raw coal on belt conveyor 1 first passes through vision acquisition device 3. Vision acquisition device 3 uses a binocular stereo camera to acquire images of the coal and gangue on belt conveyor 1 and uploads the images to a host computer. The host computer processes and analyzes the images to obtain the location information and particle size characteristics of the gangue. Based on this information, the host computer assigns tasks to the robotic arms and formulates sorting control strategies, transmitting corresponding instructions to the robotic arm controller. After the target gangue reaches the designated position under the conveyor belt 1, the controller, according to the sorting control strategy, performs series or parallel control on the robotic arms in each robotic arm sorting device 4, causing the robotic arms to perform corresponding sorting actions.

[0058] Figure 1The two sets of robotic arm sorting devices 4 are completely identical. Taking the first robotic arm sorting device 40 as an example, it mainly includes a support frame 400 connected to the top of the side of the gangue bin 5 away from the belt conveyor 1, robotic arm A1, robotic gripper a1, robotic arm A2, robotic gripper a2, and industrial camera 401, etc. The support frame 400 is U-shaped with its opening facing the belt conveyor 1. The support frame 400 straddles the belt conveyor 1, such as... Figure 1 , 2 As shown. Robotic arms A1 and A2 are both six-axis robotic arms, and the entire robotic arm can slide along the X-direction, thus possessing 7 degrees of freedom. Robotic arms A1 and A2 are staggered in the Z-axis direction to ensure that both can traverse the entire range of movement in the X-direction. Robotic arm A1 cooperates with robotic gripper a1, and robotic arm A2 cooperates with robotic gripper a2, completing the corresponding sorting actions according to the controller's instructions. Industrial camera 401 is installed at the end of robotic arms A1 and A2. Industrial camera 401 and the robotic arms form a hand-eye system, which, in conjunction with vision acquisition device 3, enables dynamic tracking of the target gangue, preventing the target gangue from being lost due to changes in conveyor belt speed or other factors. Robotic arms A1 and A2 work in the same shared space, and can work independently or collaboratively, but collisions between them must be avoided.

[0059] To enable the robotic arm to perform multiple sorting functions, it needs to be equipped with a multi-functional robotic gripper, such as... Figure 3As shown. The robotic gripper includes a base 402, a connecting bracket 410, a cylinder 403, a servo motor 404, a connecting shaft 405, and a linkage structure. The connecting bracket 410 is used to connect the base 402 and the robotic arm. The connecting bracket 410 is connected to the middle position of the base 402. There are two cylinders 403, two servo motors 404, two connecting shafts 405, and two linkage structures, which are symmetrically arranged on the base 402. The linkage structure on each side of the base 402 includes two parallelogram linkage mechanisms. The parallelogram linkage mechanism includes a first linkage 406, a second linkage 407, a third linkage 408, and a fourth linkage 409. The first linkage 406 and the third linkage 408 are arranged in parallel, and the second linkage 407 and the fourth linkage 409 are arranged in parallel. The first link 406 is connected to the second link 407, the first link 406 is connected to the fourth link 409, and the third link 408 is connected to the fourth link 409 via pins. The third link 408 is connected to the worm gear shaft of the servo motor 404 and rotates around the worm gear shaft. The second link 407 is connected to the worm gear shaft via a key and rotates with the worm gear shaft. Utilizing this characteristic, the drive of the first link 406 can be transferred to the third link 408, avoiding the need to place the drive element on the first link 406, while simultaneously increasing the rigidity of the second link 407. One end of cylinder 403 is hinged to connecting bracket 410, and the other end is hinged to connecting shaft 405. The third connecting rod 408, located in the same linkage structure, is hinged to both ends of the connecting shaft 405 on the same side. Cylinder 403 drives the two third connecting rods 408 on the same side via connecting shaft 405, thereby controlling the first connecting rod 406 to achieve the corresponding action. Servo motor 404, through internal worm gear transmission, controls the second connecting rod 407 to achieve the transformation of the robotic gripper's functional form. Simultaneously, the reverse self-locking characteristic of the worm gear ensures that the robotic gripper maintains its working form. Because servo motor 404 only needs to overcome the resistance and frictional resistance generated by the weight of the linkage mechanism, its power and size are greatly reduced. This multi-functional robotic gripper has a compact overall structure and can quickly achieve functional form transformations through the drive of servo motor 404.

[0060] The functional forms of robotic grippers can be divided into two types: grasping form and deflecting form, such as... Figure 5As shown in the diagram, the robotic gripper's grasping posture is also its initial lowering position. The gripper's opening can be adjusted by the servo motor 404 according to the size of the target gangue. The gripper is lowered vertically downwards, making full use of the extremely small space at the end of the first link 406. In situations where coal and gangue are densely packed, it can insert into the gaps between the coal and gangue, minimizing the probability of gripper collision. The robotic gripper's release posture is based on the grasping posture. The servo motor 404 swings one side of the linkage mechanism upwards, above the base 402. At this time, the gripper is in a two-finger release posture. Under the mechanical limit of the cylinder 403 and the reverse self-locking action of the worm gear, the release posture of the gripper is stably maintained.

[0061] Combined with a multi-functional robotic gripper, the robotic arm sorting device 4 can perform sorting actions such as... Figure 4 As shown, the robotic arm's sorting actions include: single-arm grasping under serial control (…). Figure 5 A2 in the series control of single-arm disengagement (A2 in the series control) Figure 5 A1 in the middle), dual-arm cooperative grasping under parallel control ( Figure 6 In series mode, the robotic arm can work independently to sort gangue, while in parallel mode, two robotic arms in the same robotic arm sorting device 4 work together to grab gangue.

[0062] A schematic diagram of the serial robotic arm sorting method is shown below. Figure 5 As shown, the grasping method involves the coordinated grasping postures of the robotic arm and robotic gripper to pick up the gangue from the conveyor belt and transfer it to the gangue bin 5; the separating method involves the coordinated separating postures of the robotic arm and robotic gripper to separate the gangue from the conveyor belt and transfer it to the gangue bin 5. A schematic diagram of the parallel robotic arm sorting method is shown below. Figure 6 As shown, the collaborative gripping method consists of two parallel robotic arms forming a closed chain, with the two robotic grippers in a separating mode, to grab large gangue from the conveyor belt and transfer it to the gangue bin 5.

[0063] Dual robotic arms, through series-parallel conversion, can adapt to the sorting of gangue of various sizes, effectively reducing the size and power of a single robotic arm. The application scenarios targeted by dual robotic arm series-parallel conversion are mainly divided into four types, such as... Figure 7 As shown.

[0064] Application Scenario 1: The gangue particle size is between 200 mm and 300 mm. The gangue is located in the middle of the conveyor belt, which means that the gangue is surrounded by coal and is wrapped in the middle of the coal. There is a lot of coal between the gangue and the edge of the conveyor belt. In this application scenario, since the gangue particle size is moderate, if the sorting method is used to separate it, some of the surrounding coal will be separated, resulting in coal waste. Therefore, a single-arm gripping sorting action under series control is used to sort the gangue.

[0065] Application Scenario 2: The gangue particle size is between 200 mm and 300 mm, and the gangue is located in the edge area of ​​the conveyor belt, that is, the amount of coal between the gangue and the edge of the conveyor belt is small. In this application scenario, since the gangue particle size is moderate and the gangue is close to the edge of the conveyor belt in belt conveyor 1, the gangue is sorted by a single-arm separation sorting action under series control.

[0066] Application Scenario 3: The gangue particle size is greater than 300 mm. The gangue is located in the middle area of ​​the conveyor belt, surrounded by coal. There is a large amount of coal between the gangue and the edge of the conveyor belt. In this application scenario, due to the large size of the gangue particles, if a single-arm gripping sorting action is adopted, the load on the robotic arm will be large, the power loss of the robotic arm will be large, and it will be easy to damage the robotic arm. Therefore, a dual-arm collaborative gripping sorting action under parallel control is adopted to sort the gangue.

[0067] Application Scenario 4: The gangue particle size is greater than 300 mm, the gangue is located in the edge area of ​​the conveyor belt, and the amount of coal between the gangue and the edge of the conveyor belt is small. In this application scenario, since the gangue particle size is large and the gangue is close to the edge of the conveyor belt in belt conveyor 1, the gangue is sorted by a single-arm separation sorting action under series control.

[0068] A control method for a multi-robotic arm gangue sorting system with series-parallel conversion, referring to Figure 8 Based on the image recognition information of gangue location and features obtained by the vision acquisition device 3 and the distribution information of surrounding coal, a sorting task is specified. In order to achieve efficient and accurate sorting, a suitable threshold is first set for the amount of coal Q between gangue and the edge of the conveyor belt. If it is below the threshold, a single-arm separation function is used. If it is above the threshold, a series and parallel sorting task is specified according to the size of the gangue. Sorting actions such as single-arm gripping, separation or double-arm coordinated gripping are adopted to effectively improve the sorting accuracy and sorting efficiency of gangue.

[0069] The serial-parallel sorting task is based on the KM algorithm. The KM algorithm is used to solve the optimal matching problem of the weighted bipartite graph composed of gangue by the robotic arm. Then, the artificial potential field + RRT algorithm is used to plan the path of multiple robotic arms.

[0070] by Figure 9 The following scenario illustrates the sorting control strategy. This scenario is a combination of the four application scenarios mentioned above and is a common complex combination in gangue sorting. G1 and G3 are gangue with a particle size greater than 300 mm, while G2 and G4 are gangue with a particle size between 200 mm and 300 mm.

[0071] The KM algorithm needs to satisfy the multi-robotic arm collaborative sorting rules, as follows:

[0072] Rule 1: Each robotic arm can only perform one sorting task at a time;

[0073] Rule 2: Two robotic arms working in the same sorting area should avoid collisions;

[0074] Rule 3: Two robotic arms working in the same sorting area shall follow the series-parallel conversion control strategy;

[0075] Rule 4: The robotic arm prioritizes sorting gangue that is closest to it;

[0076] Rule 5: In the event of task overflow, prioritize the execution of large gangue sorting tasks;

[0077] Rule 6: When the robotic arm is performing its task, it should avoid damaging the information of the waste rock behind it as much as possible;

[0078] Rule 7: Try to ensure that each robotic arm is performing a task.

[0079] Based on the above rules, for Figure 9 In the scenario, a weighted bipartite graph of the robotic arm and the gangue is constructed, and the KM algorithm is used to solve for the gangue task allocation relationship corresponding to each robotic arm, i.e., the optimal matching bipartite graph, as shown below. Figure 10 As shown, G1 has a particle size greater than 300 mm, while G2, G3, and G4 all have particle sizes between 200 and 300 mm. According to rule 5, the priority order for sorting gangue is to sort G1 first, and then sort G2, G3, and G4 according to rule 4. However, since G1 and G2 are close to each other, and the conveyor belt on the belt conveyor generally has a certain degree of elasticity, if G1 is sorted first, the conveyor belt will bounce after G1 is picked up due to its large weight, which will disturb G2 which is close to G1. Therefore, according to rule 6, G2 should be sorted first, and then G1 should be sorted. Since G3 is close to robotic arm A2, according to rule 4, robotic arm A2 is assigned to use the separation method to perform the sorting task of gangue G3, robotic arm A1 is assigned to use the gripping method to perform the sorting task of gangue G2, and robotic arms B1 and B2 cooperate to use the cooperative gripping method to perform the sorting task of gangue G1. The sorting of gangue G4 is arranged in the next task allocation.

[0080] After multiple robotic arms complete task allocation, it is necessary to plan the paths for each robotic arm to perform sorting tasks. This involves quickly finding the shortest path while avoiding obstacles, including coal, gangue, conveyor belts, and the robotic arms themselves, with the robotic arms being the most significant obstacle. Based on these requirements, the RRT algorithm is used for path planning among the multiple robotic arms. Figure 11As shown, an artificial potential field is added to the RRT algorithm, specifically the attraction and repulsion forces. Taking the random node Ki in the figure as an example, it will be affected by attraction and repulsion forces during its expansion. The attraction force guides the random node to grow towards the target object, while the repulsion force restricts the random node from expanding towards obstacles, reducing the number of invalid nodes.

[0081] To ensure the continuity of displacement, velocity, and acceleration during the movement of the robotic gripper along the path, a hybrid curve trajectory is used to control the robotic arm. The hybrid curve trajectory includes a mixture of linear motion segments and polynomial curve segments. The polynomial curve segments use fifth-order polynomials, which can match the boundary conditions of displacement, velocity, and acceleration at the start and end points, while ensuring that the first and second derivatives are smooth.

[0082] The multi-robotic arm collaborative serial-parallel sorting control strategy based on serial-parallel transformation control, task allocation, and path planning is as follows: Figure 12 As shown, based on the number of idle robotic arms, the same number of gangue stones preceding the conveyor belt are selected as a gangue matching group for task allocation. According to the task allocation results, for unassigned gangue stones, if they are within the sorting range, they are added back to the gangue matching group. For robotic arms without assigned tasks, their idle number is updated. For robotic arms that have received tasks, the gripper shape is changed according to the task type, and the robotic arm is controlled to complete the gangue sorting task according to the planned path. Finally, the task is added to the idle robotic arm sequence. This multi-robotic arm gangue sorting system, through this collaborative sorting control strategy, can achieve efficient and accurate sorting of medium and large-sized gangue stones, providing a new approach to gangue sorting. The operation flowchart of the multi-robotic arm gangue sorting device based on this sorting control method's series-parallel transformation is shown below. Figure 13 As shown.

[0083] In summary, this invention employs a binocular stereo camera in conjunction with a robotic arm hand-eye system to achieve the identification and dynamic tracking of gangue. It focuses on the robotic arm sorting device 4, designing a multi-functional robotic gripper capable of grasping and separating objects, and cooperating with the robotic arm to achieve a series-parallel transformation sorting method for gangue. A series-parallel transformation control strategy is also formulated, effectively reducing the size and power of the robotic arm and improving the sorting accuracy and efficiency of gangue. To achieve efficient sorting in the multi-robotic arm sorting system, the KM algorithm is used to allocate tasks to the multi-robotic arm gangue groups to obtain the optimal task matching. Then, an artificial potential field + RRT algorithm is used for path planning of the multi-robotic arms, introducing attraction and repulsion into the RRT algorithm to reduce the generation of invalid nodes and improve planning efficiency. A hybrid curve trajectory is used to control the robotic arms to ensure the smoothness of movement. Finally, a multi-robotic arm collaborative sorting control strategy is formulated to achieve fast and accurate sorting of gangue. The multi-robotic arm gangue sorting system based on series-parallel transformation can achieve rapid and accurate sorting of medium and large gangue, providing a new method for the application of robotic arms in the field of gangue sorting.

[0084] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined by the scope of the claims.

Claims

1. A control method for a multi-robotic arm gangue sorting system with series-parallel conversion, characterized in that, A multi-robotic arm gangue sorting system with series-parallel conversion includes: Belt conveyor (1), and Vibrating screening device (2), which is set at the feeding end of the belt conveyor (1) and is used to screen out coal and gangue with a particle size greater than 200mm and transfer them to the belt conveyor (1). The robotic arm sorting device (4) is provided in multiple ways along the conveying direction of the belt conveyor (1). Each robotic arm sorting device (4) includes two multi-degree-of-freedom robotic arms. The robotic arms are connected to robotic grippers for sorting gangue on the belt conveyor (1). The functional forms of the robotic grippers can be divided into two types: gripping form and separating form. The controller is used to control the robotic arm to perform sorting actions. The controller controls two robotic arms to perform sorting actions independently under series control or controls two robotic arms in the same robotic arm sorting device (4) to perform sorting actions collaboratively under parallel control. The multi-robotic arm gangue sorting control method with series-parallel conversion includes: Based on the image recognition obtained by the visual acquisition device (3), the location and feature information of the gangue and the distribution information of the surrounding coal are used to specify the sorting task; If the amount of coal between the gangue and the edge of the conveyor belt is lower than the preset threshold, a single-arm separation method will be used for sorting. If the amount of coal between the gangue and the edge of the conveyor belt is higher than the preset threshold, then a series-parallel sorting task is formulated according to the size of the gangue, and sorting is carried out by single-arm gripping under series control or double-arm cooperative gripping under parallel control according to the size of the gangue particles.

2. The control method for the multi-robotic arm gangue sorting system with series-parallel conversion according to claim 1, characterized in that, The sorting actions include single-arm grasping under serial control, single-arm disengagement under serial control, and dual-arm collaborative grasping in the same robotic arm sorting device (4) under parallel control.

3. The control method for the multi-robotic arm gangue sorting system with series-parallel conversion according to claim 1, characterized in that, The visual acquisition device (3) is set between the vibration screening device (2) and the robotic arm sorting device (4). The visual acquisition device (3) acquires images of coal and gangue on the belt conveyor (1) through a binocular stereo camera, providing a basis for the controller to control the robotic arm sorting action.

4. The control method for the multi-robotic arm gangue sorting system with series-parallel conversion according to claim 1, characterized in that, An industrial camera (401) is installed on the robotic arm. The industrial camera (401) and the robotic arm form a hand-eye system for dynamically tracking the state of the gangue on the belt conveyor (1).

5. The control method for the multi-robotic arm gangue sorting system with series-parallel conversion according to claim 1, characterized in that, The serial-parallel sorting task is based on the KM algorithm. The KM algorithm is used to find the optimal matching solution for the weighted bipartite graph composed of gangue in the robotic arm. The specific rules for solving the KM algorithm are as follows: Rule 1: Each robotic arm can only perform one sorting task at a time; Rule 2: Prevent collisions between two robotic arms working in the same sorting area; Rule 3: Two robotic arms working in the same sorting area shall follow the series-parallel conversion control strategy; Rule 4: The robotic arm prioritizes sorting gangue that is closest to it; Rule 5: In the event of task overflow, prioritize the execution of large gangue sorting tasks; Rule 6: When the robotic arm is performing its task, it should try not to damage the information of the gangue behind it; Rule 7: Try to ensure that each robotic arm is performing a task.

6. The control method for the multi-robotic arm gangue sorting system with series-parallel conversion according to claim 1, characterized in that, After solving the problem using the KM algorithm, the improved RRT algorithm is used for path planning of multiple robotic arms.

7. The control method for the multi-robotic arm gangue sorting system with series-parallel conversion according to claim 1, characterized in that, Introducing attraction and repulsion into the RRT algorithm.

8. The control method for the multi-robotic arm gangue sorting system with series-parallel conversion according to claim 1, characterized in that, A hybrid curve trajectory is used to control the movement path of the robotic arm.

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