Material transfer system vibration suppression method based on multi-manipulator motion direction collaborative planning

Abstract

The invention provides a material transfer system vibration suppression method based on multi-manipulator motion direction collaborative planning, and belongs to the field of vibration control and optimizing.According to the material transfer system vibration suppression method, on the basis of material transfer scheme selection, a simulation calculation mode is adopted, multiple manipulators are controlled to complete material transfer through a vibration counteracting movement strategy, and the material transfer efficiency is improved. Motion parameters of the manipulator are calculated according to the feasible transfer scheme, a manipulator motion database is established according to the motion parameters, and finally the actual transfer task is completed. The method is applied to the multi-manipulator material transfer equipment, is simple to implement, and is an effective solution for reducing the vibration of the multi-manipulator material transfer equipment.

Description

Technical Field

[0001] The present invention relates to the field of vibration control and optimization, and more specifically, to a vibration suppression method for a material transfer system based on collaborative planning of motion directions of multiple manipulators. Background Art

[0002] When multiple manipulators move inside the material transfer system, they will generate continuously changing interaction forces on the equipment, causing the equipment structure to vibrate, affecting the structural strength of the entire transfer system and the accuracy of the manipulator in completing the transfer task. Early multi-manipulator material transfer systems mainly relied on adjusting the structural stiffness of the equipment and adding vibration isolation devices to reduce the vibration of the system. Such methods usually require a long equipment debugging cycle and additional equipment debugging costs. Equipment vibration suppression from the perspective of manipulator motion control requires a short debugging cycle and low cost. Obviously, for the vibration suppression problem of multi-manipulator material transfer systems, a vibration suppression method based on the manipulator motion control level is a simple and effective solution. Summary of the invention

[0003] In order to solve the above problems, the present invention aims to disclose a vibration suppression method for a material transfer system based on collaborative planning of multi-manipulator motion directions, in particular, a manipulator movement strategy based on motion direction offset, a vibration suppression method for a multi-manipulator material transfer system by generating and screening transfer plans to determine an effective transfer plan, and simulating and solving the manipulator motion parameters;

[0004] In order to achieve the above object, the technical solution adopted by the present invention mainly includes the following processes:

[0005] Step 1: Determine the transfer space within the equipment structure based on the equipment structure of the actual material transfer system, randomly generate F positions of materials to be transferred in the transfer space, and randomly generate the target transfer position of each material to be transferred. The value of F is less than or equal to the maximum number of materials to be transferred that the transfer space can accommodate.

[0006] The material transfer system has an actual material transfer task, which includes an equipment frame, a plurality of movable manipulators capable of grabbing materials, a transmission mechanism for driving the manipulators to move within the equipment structure, and a controller for controlling the manipulators to complete the mobile grabbing action;

[0007] The transfer space is the working area of ​​the manipulator, and the initial position and target transfer position of the material to be transferred are both within the transfer space;

[0008] Step 2: Generate a transfer plan for transferring all materials to be transferred. Each transfer plan contains the order in which all materials to be transferred are transferred, and different transfer plans contain different transfer orders.

[0009] Step 2a, generating M different transfer plans, each plan transfers all the materials to be transferred in a different order, and the M transfer plans constitute a transfer plan family, and the value of M is less than or equal to the total number of materials to be transferred in the transfer space;

[0010] Step 2b, select two transfer schemes in the current transfer scheme family, mark N different materials to be transferred, select one of the materials to be transferred in turn, and exchange the transfer order of the material to be transferred in the two selected transfer schemes, and finally obtain two sub-transfer schemes, where the integer N is greater than zero and less than half of the total number of materials to be transferred;

[0011] Step 2c, repeat step 2b until all the transport plans in the current transport plan family are traversed;

[0012] Step 2d, mark the P transfer plans in the current transfer plan family, select one of the transfer plans in turn, and exchange the transfer order of any two materials to be transferred in the transfer plan. Each exchange obtains a sub-transfer plan, and the value of P is less than or equal to the total number of transfer plans contained in the current transfer plan family;

[0013] Step 2e, respectively add the sub-transportation plans generated in steps 2b, 2c, and 2d to the current transport plan family;

[0014] Step 2f, manipulator movement strategy based on movement direction offset: select a transfer plan, assign the materials to be transferred to the nearest manipulator in the transfer order of the transfer plan, control the task manipulator to move twice to complete the assigned transfer task, the first movement is for the task manipulator to move to the position of the material to be transferred, the second movement is for the task manipulator to grab the material to be transferred and then move it to the target transfer position and put it down, select the idle manipulator to transfer the material to be transferred later in the order, and the direction of the two movements of the idle manipulator is opposite to the direction of the two movements of the corresponding task manipulator, and the idle manipulator and the task manipulator start moving at the same time;

[0015] Step 2g, select a transfer scheme and import it into step 2f, all manipulators complete the transfer task with the manipulator movement strategy that offsets the movement direction in step 2f, calculate the vector sum of all manipulator displacement vectors after each movement, use the absolute value of the vector sum as a single movement evaluation index, and accumulate the single movement evaluation index corresponding to each movement as the total evaluation index of the corresponding transfer scheme;

[0016] Step 2h, evaluating all the transport solutions in the current transport solution family using the transport solution evaluation method in step 2g, and eliminating the first X transport solutions with higher total evaluation index values ​​in the transport solution family, where the value of X is less than or equal to half of the transport solutions contained in the current transport solution family;

[0017] Step 2i, repeating steps 2b to 2h until the ratio of the minimum value to the maximum value of the total evaluation index obtained in step 2h is within the set threshold range r, and selecting five to ten transportation plans with the lowest total evaluation index values ​​in the transportation plan family as the reserved transportation plans, with the range r being 0.9 to 1;

[0018] The content of the transfer plan is the order in which the materials to be transferred are transferred. In step 2f, if the idle manipulator selects the materials to be transferred with a later transfer order for transfer, the actual transfer order of the transferred materials to be transferred is advanced;

[0019] The single movement evaluation index refers to the absolute value of the vector sum of the displacement vectors of all manipulators after the task manipulator and the idle manipulator start to move at the same time in step 2f. When the manipulator moves in the opposite direction, the force applied to the device is opposite, thereby reducing the vibration of the device. The absolute value of the vector sum of the displacement vectors of all manipulators is used to evaluate the vibration cancellation status of the task manipulator and the idle manipulator after moving in different directions;

[0020] Step 3, sequentially import the reserved transfer scheme obtained in step 2i into the dynamic simulation environment, and use the manipulator movement strategy based on motion direction offset in step 2f to assign all manipulators to sequentially transfer all materials to be transferred and calculate the corresponding amplitude of the equipment, and take K times the obtained amplitude as the equipment limit amplitude, where K ranges from 0.5 to 0.9;

[0021] The dynamic simulation environment is a simulation computing environment for a material transfer system. In the simulation computing environment, all manipulators simulate the transfer of materials to be transferred in the transfer sequence in the transfer plan, and calculate and solve the vibration amount of the equipment structure at each time point when the manipulator moves;

[0022] Step 4, import a reserved transfer plan generated by step 2i into the dynamic simulation environment, the manipulator completes the transfer task with the manipulator movement strategy based on the movement direction offset in step 2f, changes the maximum acceleration value of each movement of the manipulator, makes the amplitude of the equipment lower than the equipment limit amplitude described in step 3, and then calculates the single movement evaluation index corresponding to each movement according to the method in step 2g, uses the calculated single movement evaluation index as the data index, uses the maximum acceleration value of the manipulator during each movement as the characteristic value, and stores it in the manipulator motion database in the form of the characteristic value corresponding to the data index;

[0023] The method in step 2g is used to calculate the single movement evaluation index corresponding to each movement. The corresponding transfer plan needs to be imported into step 2 to determine the step-by-step movement content of all manipulators to complete the transfer task, and then the single movement evaluation index corresponding to the movement is calculated in turn based on each movement of the task manipulator and the idle manipulator;

[0024] Preferably, in step 2f, the time required for the robot to move a unit length is L, and it is used to calculate the time required for the robot to move any length. In step 4, the maximum acceleration value when the robot moves is changed. If the amplitude of the device cannot be lower than the maximum amplitude of the device described in step 3, L is extended and step 4 is executed again.

[0025] Step 5, select a plan from the reserved transport plans generated in step 2i, use the method in step 2g to calculate the single movement evaluation index corresponding to each movement, take all the single movement evaluation indexes as search values ​​in turn, search for the corresponding feature values ​​in the manipulator motion database, and if the search is empty, import the reserved transport plan into step 4 to add data to the manipulator motion database;

[0026] The method of using a single movement evaluation index as a retrieval value to retrieve the corresponding characteristic value in the manipulator motion database is as follows: using the single movement evaluation index value as the retrieval value, if there is a data index equal to the retrieval value, then the characteristic value corresponding to the data index is the retrieval result; if there is a data index larger than the retrieval value, and there is a data index smaller than the retrieval value, then take the larger data index and the smaller data index closest to the retrieval value, linearly interpolate the two with their respective corresponding characteristic values, and calculate the retrieval result; if the retrieval value is greater than or less than all data indexes, the retrieval is empty.

[0027] Step 6: Repeat step 5 until the reserved transport plan generated in step 2i is traversed;

[0028] Step 7, repeat steps 1 to 6 until the data in the robot motion database in step 5 no longer increases;

[0029] Step 8. In the actual transfer task, first import the positions of all materials to be transferred and their corresponding target transfer positions, execute step 2, and use the transfer plan corresponding to the minimum total evaluation index value in step 2i as the final transfer plan. Based on the final transfer plan, use the method in step 2g to calculate the single movement evaluation index corresponding to each movement, take the largest single movement evaluation index value as the retrieval value, retrieve the corresponding eigenvalue in the manipulator motion database, and all manipulators use this eigenvalue as the maximum acceleration. Based on the manipulator movement strategy and the final transfer plan with the movement direction offset in step 2f, complete the actual transfer task.

[0030] The initial position and target transfer position of the material to be transferred in steps 1 to 7 are randomly generated. Steps 1 to 7 are executed to increase the data content in the motion database. When the material to be transferred is actually transferred, the transfer plan corresponding to the minimum total evaluation index value in step 2i is used as the final transfer plan. The maximum acceleration of all manipulators during actual movement is retrieved from this plan. DETAILED DESCRIPTION

[0031] The following are specific embodiments of the present invention:

[0032] Step 1: The transfer space of the manipulator is determined by the equipment structure of multi-manipulator material transfer, and the transfer range of the manipulator is limited. F positions of the materials to be transferred are randomly generated in the transfer space, and the target transfer position of each material to be transferred is randomly generated. The initial position and the target transfer position of the material to be transferred are both within the transfer space, and the value of F is less than or equal to the maximum number of materials to be transferred that the transfer space can accommodate;

[0033] The manipulator moves within the equipment structure of the material transfer system to move to the initial position and the target transfer position of the material to be transferred, and the direction of movement of the manipulator is the composite direction of two mutually perpendicular directions in the Cartesian space;

[0034] Step 2: Generate a transfer plan for all materials to be transferred;

[0035] Step 2a, generating M different transfer plans, each plan transfers all the materials to be transferred in a different order, the M transfer plans constitute a transfer plan family, and the value of M is less than or equal to the total number of materials to be transferred;

[0036] Step 2b, select two transfer schemes in the current transfer scheme family, mark N different materials to be transferred, select one of the materials to be transferred in turn, and exchange the transfer order of the material to be transferred in the two selected transfer schemes, and finally obtain two sub-transfer schemes, where the integer N is greater than zero and less than half of the total number of materials to be transferred;

[0037] Step 2c, repeat step 2b until all the transport plans in the current transport plan family are traversed;

[0038] Step 2d, mark the P transfer plans in the current transfer plan family, select one of the transfer plans in turn, and exchange the transfer order of any two materials to be transferred in the transfer plan. Each exchange obtains a sub-transfer plan, and the value of P is less than or equal to the total number of transfer plans contained in the current transfer plan family;

[0039] Step 2e, respectively add the sub-transportation plans generated in steps 2b, 2c, and 2d to the current transport plan family;

[0040] Step 2f, manipulator movement strategy based on movement direction offset: select a transfer plan, assign the materials to be transferred to the nearest manipulator in the transfer order of the transfer plan, control the task manipulator to move twice to complete the assigned transfer task, the first movement is for the task manipulator to move to the position of the material to be transferred, the second movement is for the task manipulator to grab the material to be transferred and then move it to the target transfer position and put it down, select the idle manipulator to transfer the material to be transferred later in the order, and the direction of the two movements of the idle manipulator is opposite to the direction of the two movements of the corresponding task manipulator, and the idle manipulator and the task manipulator start moving at the same time;

[0041] Step 2g, select a transfer scheme and import it into step 2f, all manipulators complete the transfer task with the manipulator movement strategy that offsets the movement direction in step 2f, calculate the vector sum of all manipulator displacement vectors after each movement, use the absolute value of the vector sum as a single movement evaluation index, and accumulate the single movement evaluation index corresponding to each movement as the total evaluation index of the corresponding transfer scheme;

[0042] Step 2h, evaluating all the transport solutions in the current transport solution family using the transport solution evaluation method in step 2g, and eliminating the first X transport solutions with higher total evaluation index values ​​in the transport solution family, where the value of X is less than or equal to half of the transport solutions contained in the current transport solution family;

[0043] Step 2i, repeating steps 2b to 2h until the ratio of the minimum value to the maximum value of the total evaluation index obtained in step 2h is within the set threshold range r, and selecting five to ten transportation plans with the lowest total evaluation index values ​​in the transportation plan family as the reserved transportation plans, with the range r being 0.9 to 1;

[0044] Changing the value of M in step 2a, the value of N in step 2b, and the value of P in step 2d to reduce the number of repetitions of the iterative process in step 2i;

[0045] When the task manipulator transfers the material to be transferred, there are one or more idle manipulators transferring the material to be transferred at a later order; if when transferring any material to be transferred at a later order, there is no idle manipulator whose two movements are opposite to the direction of the two movements of the corresponding task manipulator, then only the task manipulator is driven to perform the transfer task, and the other manipulators remain stationary;

[0046] In step 2h, X transport schemes with higher total evaluation index values ​​are eliminated, and an attempt is made to retain transport schemes with the highest total evaluation index values ​​not greater than X, so as to reduce the number of repetitions in step 2i;

[0047] Step 3, sequentially import the reserved transfer scheme obtained in step 2i into the dynamic simulation environment, and use the manipulator movement strategy based on motion direction offset in step 2f to assign all manipulators to sequentially transfer all materials to be transferred and calculate the corresponding amplitude of the equipment, and take K times the obtained amplitude as the equipment limit amplitude, where K ranges from 0.5 to 0.9;

[0048] Before building the dynamic simulation environment, it is necessary to simplify the equipment structure of the material transfer system, determine the movement direction and range of each manipulator, mark the fixed position on the equipment structure, and calculate the corresponding displacement of the position at each time point when the manipulator moves. The displacement is the vibration amount.

[0049] Step 4, import a reserved transfer plan generated by step 2i into the dynamic simulation environment, the manipulator completes the transfer task with the manipulator movement strategy based on the movement direction offset in step 2f, changes the maximum acceleration value of each movement of the manipulator, makes the amplitude of the equipment lower than the equipment limit amplitude described in step 3, and then calculates the single movement evaluation index corresponding to each movement according to the method in step 2g, uses the calculated single movement evaluation index as the data index, uses the maximum acceleration value of the manipulator during each movement as the characteristic value, and stores it in the manipulator motion database in the form of the characteristic value corresponding to the data index;

[0050] Based on the manipulator movement strategy of offsetting the movement direction in step 2f, the task manipulator and the idle manipulator move twice to transfer the materials to be transferred, and both start to move at the same time, marking the position where the equipment vibration amount is calculated and solved in step 3, and calculating and solving the amplitude of the position each time the manipulator moves in the simulation environment, and then changing the maximum acceleration of the manipulator each time it moves, so that the amplitude obtained by the solution is lower than the equipment limit amplitude described in step 3;

[0051] Step 5, select a plan from the reserved transport plans generated in step 2i, use the method in step 2g to calculate the single movement evaluation index corresponding to each movement, take all the single movement evaluation indexes as search values ​​in turn, search for the corresponding feature values ​​in the manipulator motion database, and if the search is empty, import the reserved transport plan into step 4 to add data to the manipulator motion database;

[0052] In step 5, a scheme is selected from the reserved transport schemes generated in step 2i, and a single movement evaluation index is used as a search value to detect whether the search value has a corresponding characteristic value in the manipulator motion database, and the characteristic value is the maximum acceleration applicable to the manipulator after the single movement evaluation index is calculated;

[0053] By changing the position of the material to be transferred in step 1 and the corresponding target transfer position, repeating step 5, the content in the robot database is increased;

[0054] Step 6: Repeat step 5 until the reserved transport plan generated in step 2i is traversed;

[0055] Step 7, repeat steps 1 to 6 until the data in the robot motion database in step 5 no longer increases;

[0056] Step 8. In the actual transfer task, first import the positions of all materials to be transferred and their corresponding target transfer positions, execute step 2, and use the transfer plan corresponding to the minimum total evaluation index value in step 2i as the final transfer plan. Based on the final transfer plan, use the method in step 2g to calculate the single movement evaluation index corresponding to each movement, take the largest single movement evaluation index value as the retrieval value, retrieve the corresponding eigenvalue in the manipulator motion database, and all manipulators use this eigenvalue as the maximum acceleration. Based on the manipulator movement strategy and the final transfer plan with the movement direction offset in step 2f, complete the actual transfer task.

[0057] Before completing the actual transfer task, execute steps 1 to 7 to establish and improve the robot motion database. When completing the actual transfer task, complete the actual transfer task using the method in step 8.

Claims

1. A vibration suppression method for a material transfer system based on collaborative planning of motion directions of multiple manipulators, characterized in that: The following steps are involved: Step 1: Randomly generate F positions of materials to be transferred in the transfer space, and randomly generate the target transfer position of each material to be transferred, and the value of F is less than or equal to the capacity of the transfer space; Step 2: Generate a transfer plan for all materials to be transferred; Step 2a, generating M different transfer plans, each plan transfers all the materials to be transferred in a different order, the M transfer plans constitute a transfer plan family, and the value of M is less than or equal to the total number of materials to be transferred; Step 2b, select two transfer schemes in the current transfer scheme family, mark N different materials to be transferred, select one of the materials to be transferred in turn, and exchange the transfer order of the material to be transferred in the two selected transfer schemes, and finally obtain two sub-transfer schemes, where the integer N is greater than zero and less than half of the total number of materials to be transferred; Step 2c, repeat step 2b until all the transport plans in the current transport plan family are traversed; Step 2d: Mark the P transfer plans in the current transfer plan family, select one of them in turn, and exchange the transfer order of any two materials to be transferred in the transfer plan. Each exchange will obtain a sub-transfer plan. The value of P is less than or equal to the total number of transport solutions contained in the current transport solution family; Step 2e, respectively add the sub-transportation plans generated in steps 2b, 2c, and 2d to the current transport plan family; Step 2f, manipulator movement strategy based on movement direction offset: select a transfer plan, assign the materials to be transferred to the nearest manipulator in the transfer order of the transfer plan, control the task manipulator to move twice to complete the assigned transfer task, the first movement is for the task manipulator to move to the position of the material to be transferred, the second movement is for the task manipulator to grab the material to be transferred and then move it to the target transfer position and put it down, select the idle manipulator to transfer the material to be transferred later in the order, and the direction of the two movements of the idle manipulator is opposite to the direction of the two movements of the corresponding task manipulator, and the idle manipulator and the task manipulator start moving at the same time; Step 2g, select a transfer scheme and import it into step 2f, all manipulators complete the transfer task with the manipulator movement strategy that offsets the movement direction in step 2f, calculate the vector sum of all manipulator displacement vectors after each movement, use the absolute value of the vector sum as a single movement evaluation index, and accumulate the single movement evaluation index corresponding to each movement as the total evaluation index of the corresponding transfer scheme; Step 2h, evaluating all the transport solutions in the current transport solution family using the transport solution evaluation method in step 2g, and eliminating the first X transport solutions with higher total evaluation index values ​​in the transport solution family, where the value of X is less than or equal to half of the transport solutions contained in the current transport solution family; Step 2i, repeating steps 2b to 2h until the ratio of the minimum value to the maximum value of the total evaluation index obtained in step 2h is within the set threshold range r, and selecting five to ten transportation plans with the lowest total evaluation index values ​​in the transportation plan family as the reserved transportation plans, with the range r being 0.9 to 1; Step 3, sequentially import the reserved transfer scheme obtained in step 2i into the dynamic simulation environment, and use the manipulator movement strategy based on motion direction offset in step 2f to assign all manipulators to sequentially transfer all materials to be transferred and calculate the corresponding amplitude of the equipment, and take K times the obtained amplitude as the equipment limit amplitude, where K ranges from 0.5 to 0.9; Step 4, import a reserved transfer plan generated by step 2i into the dynamic simulation environment, the manipulator completes the transfer task with the manipulator movement strategy based on the movement direction offset in step 2f, changes the maximum acceleration value of each movement of the manipulator, makes the amplitude of the equipment lower than the equipment limit amplitude described in step 3, and then calculates the single movement evaluation index corresponding to each movement according to the method in step 2g, uses the calculated single movement evaluation index as the data index, uses the maximum acceleration value of the manipulator during each movement as the characteristic value, and stores it in the manipulator motion database in the form of the characteristic value corresponding to the data index; Step 5, select a plan from the reserved transport plans generated in step 2i, use the method in step 2g to calculate the single movement evaluation index corresponding to each movement, take all the single movement evaluation indexes as search values ​​in turn, search for the corresponding feature values ​​in the manipulator motion database, and if the search is empty, import the reserved transport plan into step 4 to add data to the manipulator motion database; Step 6: Repeat step 5 until the reserved transport plan generated in step 2i is traversed; Step 7, repeat steps 1 to 6 until the data in the robot motion database in step 5 no longer increases; Step 8. In the actual transfer task, first import the positions of all materials to be transferred and their corresponding target transfer positions, execute step 2, and use the transfer plan corresponding to the minimum total evaluation index value in step 2i as the final transfer plan. Based on the final transfer plan, use the method in step 2g to calculate the single movement evaluation index corresponding to each movement, take the largest single movement evaluation index value as the retrieval value, retrieve the corresponding eigenvalue in the manipulator motion database, and all manipulators use this eigenvalue as the maximum acceleration. Based on the manipulator movement strategy and the final transfer plan with the movement direction offset in step 2f, complete the actual transfer task.

2. A vibration suppression method for a material transfer system based on coordinated scheduling of motion directions of multiple manipulators according to claim 1, characterized in that: In step 5, the single movement evaluation index is used as the search value, and the corresponding characteristic value is retrieved from the manipulator motion database in the following manner: the single movement evaluation index value is used as the search value. If there is a data index equal to the search value, the characteristic value corresponding to the data index is the search result; if there is a data index larger than the search value, and there is a data index smaller than the search value, then the larger data index and the smaller data index closest to the search value are taken, and the two are linearly interpolated with their respective corresponding characteristic values ​​to calculate the search result; if the search value is greater than or less than all data indexes, the search is empty.

3. A vibration suppression method for a material transfer system based on coordinated scheduling of motion directions of multiple manipulators according to claim 1, characterized in that: In step 2f, the time required for the robot to move a unit length is L, and the time required for the robot to move any length is calculated based on it. In step 4, the maximum acceleration value when the robot moves is changed. If the device amplitude cannot be lower than the device limit amplitude described in step 3, then extend L and re-execute step 4.