Control method of multi-station manipulator for stamping washing machine shell

Abstract

The invention relates to the technical field of machine intelligence, in particular to a control method of a multi-station manipulator for stamping a washing machine shell, which comprises the following steps of: constructing a synchronous error matrix by utilizing a station collaborative calibration experiment to determine an error transmission station sequence and an interference source station; in the working process of the station manipulator, the tail end load error coefficient of each station is determined, and the accumulative error weight of each station is determined by combining the serial number difference of each station and the interference source station in the error transmission station sequence; based on the accumulative error weight and the real-time position error of the manipulator of the interference source station, the accumulative error amount of each station is determined in combination with a synchronous error matrix; and finally, according to the real-time position error and the accumulated error amount of the manipulator of each station, an error compensation value of each station is determined, and compensation control is carried out. By determining the accumulated error amount of each station, the error compensation accuracy of the manipulator is improved.

Description

Technical Field

[0001] The present invention relates to the field of machine intelligence technology, and particularly relates to a control method for a multi-station manipulator used for stamping the outer shell of a washing machine. Background Art

[0002] In the stamping process of the outer shell of a washing machine, a multi-station manipulator is driven by a servo motor to achieve rapid positioning and transfer, and a PLC control system is combined to coordinate the actions of the punching press and the manipulator. For example, a horizontal translation structure and an auxiliary lifting design are adopted to adapt to the continuous stamping requirements of the multi-station outer shell of the washing machine. Such a manipulator can synchronously complete feeding, stamping, blanking, and transfer between stations, which can significantly reduce manual intervention and improve production efficiency.

[0003] In the existing multi-station manipulators for stamping the outer shell of a washing machine, the lack of accuracy and real-time performance in the coordinated motion control of multiple motors has become a key problem. Since the stamping process requires the manipulator to quickly switch between multiple stations, the translation and lifting actions driven by the servo motor need to be strictly synchronized with the stroke of the slider of the punching press. However, the traditional control method is prone to cumulative errors when dynamically adjusting the motion trajectories of each axis, resulting in workpiece positioning deviation or die interference. Especially, the timing coupling relationship between multiple stations is complex. When dealing with sudden disturbances, the system stability decreases, affecting the reliability of continuous production. Although the differential gain of the traditional PID controller can be used to compensate for the cumulative error, it only focuses on the instantaneous change rate of the current error and cannot effectively predict or compensate for this cross-station dynamic superposition error. Moreover, its prediction effect is limited to the local trend of a single station, so the compensation effect is not good, resulting in poor control accuracy of the multi-station manipulator. Summary of the Invention

[0004] In order to solve the above technical problem of poor control accuracy of the multi-station manipulator, the purpose of the present invention is to provide a control method for a multi-station manipulator used for stamping the outer shell of a washing machine, and the specific technical solution adopted is as follows:

[0005] In a first aspect, the present invention provides a control method for a multi-station manipulator used for stamping the outer shell of a washing machine, including the following steps:

[0006] Using a station collaborative calibration experiment, construct a synchronous error matrix, and each element in the synchronous error matrix is the asymmetric dynamic coupling strength of one station to another station;

[0007] According to the synchronous error matrix, determine the error transfer station sequence and the interference source station, and the error transfer station sequence is used to reflect the error transfer direction when different stations work together;

[0008] During the working process of the station manipulator, according to the relevant information of the end of the manipulator at different stations, determine the end load error coefficient of each station;

[0009] Determine the cumulative error weight of each station according to the sequence number difference between each station and the interference source station in the error transfer station sequence, and the difference between the end load error coefficients of each station and the interference source station;

[0010] Determine the initial cumulative error amount of each station according to the real-time position error of the manipulator of the interference source station, and the difference between the asymmetric dynamic coupling strength of each station to the interference source station and the asymmetric dynamic coupling strength of the interference source station to each station in the synchronous error matrix;

[0011] Use the cumulative error weight of each station to perform weighted multiplication on the initial cumulative error amount, and finally obtain the cumulative error amount of each station;

[0012] Determine the error compensation value of each station according to the real-time position error of the manipulator of each station and the cumulative error amount, and based on the error compensation value, perform compensation control on the manipulator of each station.

[0013] Combined with the first aspect above, in some possible implementation manners, use the station collaborative calibration experiment to construct a synchronous error matrix, including:

[0014] Apply a step acceleration excitation to different stations in the station collaborative calibration experiment, and obtain the basic coupling coefficient between station i and station j under different step acceleration excitations;

[0015] Based on the change of the basic coupling coefficient under adjacent step acceleration excitations, and combined with the included angle between the force transmission direction of the manipulator of station i and the motion axis of the manipulator of station j, the structural arm length between station i and station j, and the equivalent mass and step acceleration excitation of the manipulator of station i, determine the asymmetric dynamic coupling coefficient of station i to station j;

[0016] According to the asymmetric dynamic coupling coefficient and the distribution positions of different stations, determine the asymmetric dynamic coupling strength of the p-th station to the q-th station as the element in the p-th row and the q-th column of the synchronous error matrix.

[0017] Combined with the first aspect above, in some possible implementation manners, obtaining the basic coupling coefficient between station i and station j under different step acceleration excitations includes:

[0018] Determine the basic coupling coefficient between station i and station j under static conditions according to the position deviation between station i and station j, the structural arm length between station i and station j, and the position error of each joint point of the manipulator of station i;

[0019] In the station collaborative calibration experiment, a step acceleration excitation is continuously applied to station i to obtain the basic coupling coefficient between station i and station j under different step acceleration excitations.

[0020] Combined with the first aspect above, in some possible implementation manners, determining the asymmetric dynamic coupling coefficient of station i with respect to station j includes:

[0021] Determining the change amount of the basic coupling coefficient under adjacent step acceleration excitations, performing a linear fitting on the change amount to obtain a fitting line;

[0022] Determining the slope of the fitting line to obtain the basic coupling coefficient change slope;

[0023] According to the basic coupling coefficient change slope, and in combination with the included angle between the force transmission direction of the manipulator of station i and the motion axis of the manipulator of station j, the structural arm length between station i and station j, the equivalent mass of the manipulator of station i, and the acceleration value of the step acceleration excitation, determining the asymmetric dynamic coupling coefficient of station i with respect to station j.

[0024] Combined with the first aspect above, in some possible implementation manners, determining the asymmetric dynamic coupling strength of the p-th station with respect to the q-th station as the element in the p-th row and q-th column of the synchronization error matrix includes:

[0025] Sorting all stations in the order from upstream to downstream of the production line to obtain the serial numbers of each station;

[0026] Setting the basic element at each position on the main diagonal of the synchronization error matrix to a first value, and setting the basic element at other positions except the main diagonal of the synchronization error matrix to a second value, where the first value is greater than the second value;

[0027] Determining the sum of the asymmetric dynamic coupling coefficient of the p-th station with respect to the q-th station and the basic element in the p-th row and q-th column of the synchronization error matrix as the asymmetric dynamic coupling strength in the p-th row and q-th column of the synchronization error matrix, thereby obtaining the synchronization error matrix.

[0028] Combined with the first aspect above, in some possible implementation manners, determining the error transmission station sequence includes:

[0029] Determining the cumulative sum of the absolute values of the upper right triangular elements in the synchronization error matrix to obtain the forward transmission strength, and determining the cumulative sum of the absolute values of the lower left triangular elements in the synchronization error matrix to obtain the reverse transmission strength;

[0030] Determining the ratio of the forward transmission strength to the reverse transmission strength to obtain a first ratio;

[0031] If the first ratio is greater than the upper bound threshold, all workstations are sorted in the order from upstream to downstream of the production line to obtain an error transfer workstation sequence. If the first ratio is less than the lower bound threshold, all workstations are sorted in the order from downstream to upstream of the production line to obtain an error transfer workstation sequence;

[0032] Otherwise, determine the sum of all column elements of each workstation in the synchronization error matrix to obtain the comprehensive interference intensity of each workstation, and sort all workstations in ascending order of the comprehensive interference intensity of all workstations to obtain an error transfer workstation sequence.

[0033] Combined with the above first aspect, in some possible implementation manners, determining the interfering source workstation includes:

[0034] Determine the sum of all row elements of each workstation in the synchronization error matrix to obtain the comprehensive interference intensity of each workstation;

[0035] Determine the maximum value among the comprehensive interference intensities of all workstations, and determine the workstation corresponding to the maximum value as the interfering source workstation.

[0036] Combined with the above first aspect, in some possible implementation manners, the information related to the end of the manipulator at least includes: the speed and distance in each action movement direction obtained by disassembling the tasks executed by the manipulators at different workstations, the motor current data when the manipulators at different workstations execute tasks, the mass of the movement axes of the manipulators at different workstations and the distance from the centroid of the manipulator to the end, and the contact force data between the manipulators at different workstations and the workpiece; determining the end load error coefficient of each workstation includes:

[0037] Determine the ratio of the speed and distance in the current action movement direction obtained by disassembling the tasks executed by the manipulator at each workstation to obtain a second ratio;

[0038] Determine the ratio of the motor current increase amount to the motor current fluctuation amount of the motor current data when the manipulator at each workstation is currently executing a task to obtain a third ratio;

[0039] Fuse the second ratio and the third ratio to determine the end load inertia of each workstation;

[0040] Determine the self-rotational inertia of each workstation according to the mass of the movement axis of the manipulator at each workstation and the distance from the centroid of the manipulator to the end;

[0041] Determine the load inertia ratio of each workstation according to the ratio of the end load inertia to the load inertia of each workstation;

[0042] According to the difference between the current contact force and the expected contact force in the contact force data between the manipulator at each workstation and the workpiece, the contact force error of each workstation;

[0043] Fuse the load inertia ratio and the contact force error to determine the end load error coefficient of each station.

[0044] Combined with the first aspect above, in some possible implementation manners, determining the cumulative error weight of each station includes:

[0045] Perform a negative correlation mapping on the difference between the serial number of each station and the serial number of the interference source station in the error transfer station sequence to obtain a serial number difference mapping value;

[0046] Determine the ratio of the end load error coefficient of each station to the end load error coefficient of the interference source station to obtain a fourth ratio;

[0047] Fuse the serial number difference mapping value and the fourth ratio to obtain the cumulative error weight of each station.

[0048] Combined with the first aspect above, in some possible implementation manners, determining the initial cumulative error amount of each station includes:

[0049] Determine the ratio of the asymmetric dynamic coupling strength of each station to the interference source station in the synchronous error matrix to the asymmetric dynamic coupling strength of the interference source station to each station to obtain a fifth ratio;

[0050] Determine the integral of the product of the real-time position error of the manipulator of the interference source station and the fifth ratio with respect to time to obtain the initial cumulative error amount of each station.

[0051] In a second aspect, the present invention further provides a control system for a multi-station manipulator used in stamping a washing machine housing, including a memory and a processor. The memory is used to store executable computer program code, and the processor is used to call and run the executable computer program code from the memory, so that the system executes the method in the first aspect or any one of the possible implementation manners of the first aspect.

[0052] In a third aspect, the present invention further provides a computer program product, which includes: computer program code, when the computer program code runs on a computer, enabling the computer to execute the method in the first aspect or any one of the possible implementation manners of the first aspect.

[0053] In a fourth aspect, the present invention further provides a computer-readable storage medium, which stores computer program code, and when the computer program code runs on a computer, enabling the computer to execute the method in the first aspect or any one of the possible implementation manners of the first aspect.

[0054] The present invention has the following beneficial effects: First, by pre-conducting a station collaboration calibration experiment to construct a synchronization error matrix, each element in the synchronization error matrix is an asymmetric dynamic coupling strength of one station to another station, and this asymmetric dynamic coupling strength reflects the error transfer strength of one station to another station; based on the distribution of the asymmetric dynamic coupling strength in the synchronization error matrix, an error transfer station sequence for reflecting the error transfer direction when different stations work together and a disturbance source station that will cause error interference to other stations are determined. Second, during the normal operation of the multi-station manipulator, based on the relevant information of the end of the manipulator at different stations, the end load error coefficient of each station is determined, and this end load error coefficient is used to reflect the error situation caused by the end load at each station; furthermore, based on the distance of error transfer between each station in the error transfer station sequence and the disturbance source station and the difference between the end load error coefficients of each station and the disturbance source station, the cumulative error weight of each station is determined to be used for weighted correction of the cumulative error amount caused by the error transfer of the disturbance source station to each station, so as to finally determine the cumulative error amount of each station. Finally, based on the real-time position error and the cumulative error amount of the manipulator at each station, the error compensation value of each station is determined and manipulator compensation control is performed. By accurately determining the cumulative error amount of each station, the present invention effectively improves the accuracy of manipulator error compensation, thereby improving the control accuracy of the multi-station manipulator. Description of the Drawings

[0055] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0056] Figure 1 It is a step flowchart of a control method for a multi-station manipulator for stamping the outer shell of a washing machine according to an embodiment of the present invention;

[0057] Figure 2 It is a step flowchart of constructing a synchronization error matrix according to an embodiment of the present invention;

[0058] Figure 3 It is a step flowchart of determining a disturbance source station according to an embodiment of the present invention;

[0059] Figure 4 It is a step flowchart of determining the end load error coefficient of each station according to an embodiment of the present invention;

[0060] Figure 5 It is a step flowchart of determining the cumulative error weight of each station according to an embodiment of the present invention;

[0061] Figure 6 Flow chart of steps for determining the cumulative error amount of each station in the embodiment of the present invention;

[0062] Figure 7 Structural schematic diagram of a control system of a multi-station manipulator for stamping a washing machine housing in the embodiment of the present invention. Detailed implementation manners

[0063] To clearly illustrate the technical features of this solution, the present invention will be elaborated in detail below through specific implementation manners in combination with the accompanying drawings.

[0064] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0065] It should be understood that the various steps recited in the method embodiments of the present invention can be executed in a different order and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this regard.

[0066] The term "including" and its variations used herein are open-ended, that is, "including but not limited to". The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0067] It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependent relationships.

[0068] In the embodiments of the present invention, although the operations or steps are described in a specific order in the drawings, it should not be understood as requiring these operations or steps to be performed in the specific order shown or in a serial order, or requiring all the operations or steps shown to obtain the desired result. In the embodiments of the present invention, these operations or steps can be performed serially; they can also be performed in parallel; or a part of these operations or steps can be performed.

[0069] Meanwhile, it can be understood that the data involved in the technical solution of the present invention (including but not limited to the data itself, the acquisition or use of data) should comply with the requirements of the corresponding laws, regulations and related provisions. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs, and all parameters or indicators in the formulas involved in the present invention are normalized values that eliminate the influence of dimensions.

[0070] To solve the problem of poor control accuracy of existing multi-station manipulators, an embodiment of the present invention provides a control method for a multi-station manipulator used for stamping the outer shell of a washing machine. This method first obtains the asymmetric dynamic coupling strength between different stations through a station collaborative calibration experiment to construct a synchronous error matrix, and then based on this synchronous error matrix, identifies the interference source station and the error transfer station sequence representing the error transfer relationship between stations; then analyzes the error caused by the difference in end loads, calculates the end load error coefficient of each station, and further determines the cumulative error weight of each station. Based on this cumulative error weight, the initial cumulative error amount caused by the error transfer of the interference source station to each station is corrected to obtain the cumulative error amount of each station; finally, according to the position error and cumulative error amount of each motion axis of the manipulator at each station, the error compensation value of each station is determined, and based on this error compensation value, compensation control is performed on the manipulator at each station. Compared with the traditional PID controller that only focuses on instantaneous changes and uses a fixed differential gain to regulate the cumulative error, the method provided by the embodiment of the present invention can make the error compensation of the manipulator in a complex multi-station collaborative scenario more accurate by analyzing the causal relationship of the cumulative error between multiple stations and the hierarchical relationship of error accumulation, effectively improving the control accuracy of the multi-station manipulator, and further improving the stamping process accuracy of the washing machine outer shell.

[0071] The following will combine the drawings to introduce in detail a control method for a multi-station manipulator used for stamping the outer shell of a washing machine provided by an embodiment of the present invention.

[0072] Figure 1 shows a schematic diagram of the basic process of a control method for a multi-station manipulator used for stamping the outer shell of a washing machine provided by an embodiment of the present invention, as Figure 1 shown, the method specifically includes the following steps:

[0073] Step S100: Use a station collaborative calibration experiment to construct a synchronous error matrix, and each element in the synchronous error matrix is the asymmetric dynamic coupling strength of one station to another station.

[0074] Specifically, for a multi-station stamping platform, taking the cantilever multi-station stamping platform as an example, the multi-station manipulator includes: a loading manipulator, a stamping auxiliary manipulator, a unloading manipulator, etc. Track and position the multi-station manipulator to determine the tracking and positioning information of the multi-station, which reflects the motion and position of the manipulators at different stations. For example, a grating encoder is integrally installed on the motion axis (i.e., the connecting rod) of the manipulator to monitor the X / Y / Z axis motion positions of the motion axis and obtain position coordinate data. A high-speed industrial camera (1000fps) is deployed between stations and cooperates with a vision algorithm for visual positioning, which is used to mutually verify with the position coordinate data measured by the grating encoder. At the same time, a six-axis force sensor is integrated at the end effector of the manipulator to detect the contact force data between it and the workpiece. Collect the real-time motion position data of the manipulator, use the Kalman filter to eliminate noise, and fuse the multi-sensor data to generate the estimated values of the motion states of the positions, speeds, and forces of each axis.

[0075] Based on the tracking and positioning information of each station, through a multi-station collaborative calibration experiment, construct a synchronous error matrix to reflect the dynamic differences during the cooperation of the multi-station manipulator. The construction of the synchronous error matrix needs to reflect the asymmetry of the dynamic coupling between stations. For example, due to the differences in motion characteristics between the loading station (station 1) and the stamping station (station 2), their error propagation weights are different.

[0076] Further, in a possible implementation manner, as Figure 2 shown, the above step S100 uses a station collaborative calibration experiment to construct a synchronous error matrix, including:

[0077] Step S101: Apply a step acceleration excitation to different stations in the station collaborative calibration experiment to obtain the basic coupling coefficient between station i and station j under different step acceleration excitations.

[0078] Specifically, there are several joints on each station manipulator. Based on the tracking and positioning information of each station, according to the deviation between the actual position of each joint on each station manipulator and the target trajectory, define the tracking error vector of each station. Taking the rth station as an example, the tracking error vector e r =[e 1, e2,…,e n ,…,e N T . Among them, e n represents the tracking error of the nth joint on the rth station manipulator, and this tracking error is equal to the difference between the expected joint angle position and the actual joint angle position of the nth joint. N represents the total number of joints on the rth station manipulator.

[0079] ​Based on the tracking error vectors of each work station, static calibration is performed using an impact test to obtain the basic coupling coefficients between different work stations under different step acceleration excitations, that is, the relative error amounts between adjacent work stations are obtained through experimental calibration. Further, in a possible implementation manner, obtaining the basic coupling coefficient between work station i and work station j under different step acceleration excitations in the above step S101 includes: determining the basic coupling coefficient between work station i and work station j under static conditions according to the position deviation between work station i and work station j, the structural arm length between work station i and work station j, and the position errors of each joint point of the manipulator of work station i; applying a step acceleration excitation to work station j in the work station collaborative calibration experiment to obtain the basic coupling coefficient between work station i and work station j under different step acceleration excitations.

[0080] Specifically, static calibration is performed using an impact test: the manipulators of each work station move independently. Taking the independent movement of any work station i as an example, the position deviation between any two work stations i and j is measured. This position error refers to the difference between the actual position distance and the set position distance between the two work stations i and j (the position deviation has positive and negative values. When it is a positive number, it means that the actual position distance between the two work stations becomes larger, and vice versa, it means that the actual position distance between the two work stations becomes smaller). Thus, based on the position deviation between work station i and work station j, the structural arm length between work station i and work station j, and the position errors of each joint point of the manipulator of work station i, the basic coupling coefficient between work station i and work station j under static conditions is calculated through the following formula:

[0081]

[0082] In the formula: f i,j represents the basic coupling coefficient between work station i and work station j under static conditions; Δx i,j represents the position deviation between work station i and work station j; L i,j represents the structural arm length between work station i and work station j; ‖e i ‖ represents the Euclidean norm of the tracking errors of all joints on work station i. Among them, the multiplication of the two in the denominator is to eliminate the influence of the mechanical structure size difference.

[0083] Through the above method, the basic coupling coefficients between different work stations under static conditions can be determined through experimental calibration, which is used to reflect the relative error amounts between different work stations.

[0084] Then, a step acceleration excitation is applied to the impact test. Taking work station i as an example, a step acceleration (amplitude 5m / s 2 , duration 50ms) is applied to work station i to obtain the basic coupling coefficient between work station i and work station j under continuous step acceleration excitations.

[0085] Step S102: Determine the asymmetric dynamic coupling coefficient of station i to station j based on the variation of the base coupling coefficient under adjacent step acceleration excitations, and in combination with the angle between the force transmission direction of the manipulator at station i and the motion axis of the manipulator at station j, the structural arm length between station i and station j, as well as the equivalent mass and step acceleration excitation of the manipulator at station i.

[0086] Specifically, for stations i and j, based on the variation of the base coupling coefficient between stations i and j under adjacent step acceleration excitations, and in combination with the angle between the force transmission direction of the manipulator at station i and the motion axis of the manipulator at station j, the structural arm length between stations i and j, the equivalent mass of the manipulator at station i, and the step acceleration excitation, the asymmetric dynamic coupling coefficient of station i to station j can be determined. The asymmetric dynamic coupling coefficient between two stations reflects the difference in the error propagation intensity from one station to another. For example, due to the directionality of inertial force transmission, the influence coefficient γ of the high acceleration at stamping station 2 on the adjacent station 3 23 may be greater than the reverse asymmetric dynamic coupling coefficient γ 32 , indicating that the interference of station errors on downstream stations is stronger at this time.

[0087] Further, in a possible implementation manner, determining the asymmetric dynamic coupling coefficient of station i to station j in the above step S102 includes: determining the change amount of the base coupling coefficient under adjacent step acceleration excitations, performing a linear fit on the change amount to obtain a fitting line; determining the slope of the fitting line to obtain the base coupling coefficient change slope; and based on the base coupling coefficient change slope, and in combination with the angle between the force transmission direction of the manipulator at station i and the motion axis of the manipulator at station j, the structural arm length between station i and station j, the equivalent mass of the manipulator at station i, and the acceleration value of the step acceleration excitation, determining the asymmetric dynamic coupling coefficient of station i to station j.

[0088] Specifically, for station i, obtain the change amount Δf of the base coupling coefficient between station i and station j under continuous step acceleration excitations i,j . Use the least squares method to fit the change amount Δf i,j to obtain the slope value of the change amount, and take this slope value as the base coupling coefficient change slope.

[0089] Then, based on the base coupling coefficient change slope, and in combination with the angle between the force transmission direction of the manipulator at station i and the motion axis of the manipulator at station j, the structural arm length between station i and station j, the equivalent mass of the manipulator at station i, and the acceleration value of the step acceleration excitation, calculate the asymmetric dynamic coupling coefficient of station i to station j through the following formula:

[0090]

[0091] In the formula: γ i,j represents the asymmetric dynamic coupling coefficient of station i to station j; θ i,j represents the included angle between the force transmission direction of the manipulator at station i and the movement axis of the manipulator at station j (this included angle is a real-time variable), and the movement axis refers to the coordinate axis direction along which the manipulator moves in three-dimensional space. For example, the manipulator can extend and retract (move along the x-axis direction), move left and right (move along the y-axis direction), and move up and down (move along the z-axis direction); L ij represents the structural arm length between station i and station j, that is, the distance between the cantilevers connected by the manipulators of all stations between station i and station j; m i represents the equivalent mass (actual mass) of the manipulator at station i; a j represents the acceleration value of the step acceleration excitation applied to station i; k represents the change slope of the basic coupling coefficient corresponding to station i and station j.

[0092] In the same way as above, according to the change rate of the basic coupling coefficient under static calibration under continuous step acceleration excitation, and the mass inertia of the station manipulator, the asymmetric dynamic coupling coefficient between any two stations can be obtained, and this asymmetric dynamic coupling coefficient reflects the difference in error propagation intensity between the corresponding two stations.

[0093] Step S103: According to the asymmetric dynamic coupling coefficient and the distribution positions of different stations, determine the asymmetric dynamic coupling strength of the p-th station to the q-th station as the element in the p-th row and the q-th column of the synchronous error matrix.

[0094] Specifically, based on the asymmetric dynamic coupling coefficient between different stations and combined with the distribution positions of different stations, a synchronous error matrix is determined. The difference in the movement trajectories of the manipulators at different stations results in the asymmetry of the coupling weights in the synchronous error matrix. For example, there should be a significant difference in the error propagation coefficient in the matrix between the fast translational movement of the manipulator at the feeding station and the high-frequency reciprocating movement at the stamping station.

[0095] Further, determining the asymmetric dynamic coupling strength of the p-th station with respect to the q-th station as the element in the p-th row and q-th column of the synchronization error matrix in step S103 includes: sorting all stations in the order from upstream to downstream of the production line to obtain the serial numbers of each station; setting the basic elements at each position on the main diagonal of the synchronization error matrix to a first value, and setting the basic elements at other positions except the main diagonal of the synchronization error matrix to a second value, where the first value is greater than the second value; determining the sum of the asymmetric dynamic coupling coefficient of the p-th station with respect to the q-th station and the basic element in the p-th row and q-th column of the synchronization error matrix as the asymmetric dynamic coupling strength in the p-th row and q-th column of the synchronization error matrix, thereby obtaining the synchronization error matrix.

[0096] Specifically, set the size of the synchronization error matrix according to the total number of stations. The synchronization error matrix is a square matrix with a size equal to the total number of stations. Sort all stations in the order from upstream to downstream of the production line to obtain the serial numbers of each station. Set the basic elements at each position on the main diagonal (the diagonal pointing from the upper left to the lower right) of the synchronization error matrix to 2, which is derived from the matrix diagonal term in the Laplacian matrix and represents the dominant contribution of the tracking error of the station itself to synchronization. If the element in the p-th row and q-th column of the synchronization error matrix is on the matrix diagonal, then 2 + γ p,q represents the asymmetric dynamic coupling strength of the p-th station with respect to the q-th station, and use it as the element value of the element in the p-th row and q-th column of the synchronization error matrix. For example, the high acceleration of the stamping station (the 2nd station) will increase its coupling coefficient with respect to the loading station (the 1st station), thereby amplifying the weight of its own diagonal. At the same time, set the basic elements at each position of the non-main diagonal of the synchronization error matrix to -1, which represents the negative feedback effect of the errors between adjacent stations in traditional cooperative control and forces the errors between stations to tend to be consistent. If the element in the p-th row and q-th column of the synchronization error matrix is not on the matrix diagonal, then -1 - γ p,q represents the asymmetric dynamic coupling strength of the p-th station with respect to the q-th station, and use it as the element value of the element in the p-th row and q-th column of the synchronization error matrix. For example, if the rapid movement of the 1st station generates additional interference to the 2nd station, the coupling term becomes more negative, enhancing the inhibitory effect. Thus, the synchronization error matrix can be determined, and this synchronization error matrix reflects the complex coupling relationship during the cooperation of the manipulators at each station.

[0097] In the above manner, by using the station cooperation calibration experiment, the synchronization error matrix of the multi-station manipulator can be constructed.

[0098] Step S200: According to the synchronization error matrix, determine the error transfer station sequence and the interference source station. The error transfer station sequence is used to reflect the error transfer direction when different stations cooperate.

[0099] Specifically, a sudden disturbance at a certain work station, such as an external force impact, will quickly spread to other work stations. By analyzing the asymmetric dynamic coupling strengths in the synchronization error matrix, the specific direction of this spread can be determined. Therefore, by extracting the row, column, and diagonal features in the error synchronization matrix, the error transfer relationship during multi-station coordination can be obtained, including the error transfer direction, the magnitude of the influence, the work station where the interference source is located, etc.

[0100] Further, in a possible implementation, as Figure 3 shown, determining the error transfer work station sequence in the above step S200 includes:

[0101] Step S201: Determine the sum of the absolute values of the upper right triangular elements in the synchronization error matrix to obtain the forward transfer strength, and determine the sum of the absolute values of the lower left triangular elements in the synchronization error matrix to obtain the reverse transfer strength.

[0102] Specifically, the elements in the diagonal direction of the synchronization error matrix reflect the error transfer direction. If the forward transfer strength (from the upper left corner to the lower right corner) is much greater than the reverse transfer strength, it indicates that the error propagates more significantly along the production line from the upstream (such as the loading work station) to the downstream (such as the unloading work station). For example, the high acceleration of the stamping work station causes a strong inertial force interference on the downstream work stations, forming an "error transfer chain".

[0103] Therefore, calculate the sum of the absolute values of the upper right triangular elements in the synchronization error matrix to obtain the forward transfer strength, which reflects the cumulative interference of the upstream work stations on the downstream work stations. At the same time, calculate the sum of the absolute values of the lower left triangular elements in the synchronization error matrix to obtain the reverse transfer strength, which reflects the feedback interference of the downstream work stations on the upstream work stations.

[0104] Step S202: Determine the ratio of the forward transfer strength to the reverse transfer strength to obtain the first ratio.

[0105] Step S203: If the first ratio is greater than the upper bound threshold, sort all work stations in the order from upstream to downstream of the production line to obtain the error transfer work station sequence. If the first ratio is less than the lower bound threshold, sort all work stations in the order from downstream to upstream of the production line to obtain the error transfer work station sequence.

[0106] Specifically, calculate the ratio of the forward transfer strength to the reverse transfer strength, and denote this ratio as the first ratio. When the first ratio is greater than the upper bound threshold, in a specific implementation, the value of the upper bound threshold is set to 1.5, and it can be determined that the error propagates forward along the production line station sequence, that is, the 1st station, the 2nd station, the 3rd station, … Therefore, all stations are sorted in the order from the upstream to the downstream of the production line to obtain the error transfer station sequence. When the first ratio is less than the lower bound threshold, in a specific implementation, the value of the lower bound threshold is set to 0.8, which means the error propagates reversely. Then, all stations are sorted in the order from the downstream to the upstream of the production line to obtain the error transfer station sequence.

[0107] Step S204: Otherwise, determine the sum of all column elements of each station in the synchronous error matrix to obtain the comprehensive interference strength of each station, and sort all stations in ascending order of the comprehensive interference strength of all stations to obtain the error transfer station sequence.

[0108] Specifically, when the first ratio is greater than the upper bound threshold or less than the lower bound threshold, it is considered that the error transfer direction is linear at this time. On the contrary, when the first ratio is between the upper and lower bound thresholds, it means that the error transfer is non-linear. At this time, the error transfer station sequence is obtained by sorting according to the column elements, that is, according to the comprehensive interference degree of each station by other stations. The specific implementation process includes: determining the sum of all elements in each column of the synchronous error matrix, and using this sum as the comprehensive interference strength of the station corresponding to this column. This comprehensive interference strength reflects the comprehensive interference strength of the corresponding station affected by all other stations. Thus, the comprehensive interference strength of each station can be obtained. If the sum of the column elements of the qth station in the synchronous error matrix (that is, the sum of all elements in the qth column of the synchronous error matrix) is lower than the average sum of elements of all columns (the sum of the element sums of each column divided by the number of columns), that is, the comprehensive interference strength of the qth station is lower than the comprehensive interference strength of other stations, it means that the qth station is most affected by external errors. Sort all stations in ascending order of the comprehensive interference strength to obtain the error transfer station sequence.

[0109] In the above manner, by analyzing the column and diagonal features in the synchronous error matrix, the error transfer station sequence can be accurately determined.

[0110] Further, in a possible implementation, as Figure 3 shown, determining the interference source station in the above step S200 includes:

[0111] Step S205: Determine the sum of all row elements of each station in the synchronous error matrix to obtain the comprehensive interference strength of each station.

[0112] Specifically, the cumulative sum of all elements in each row of the synchronization error matrix is determined, and the cumulative sum is used as the comprehensive interference strength of the workstation corresponding to the row, and the comprehensive interference strength reflects the comprehensive influence strength of the corresponding workstation on all other workstations. Thus, the comprehensive interference strength of each workstation can be obtained.

[0113] If the sum of the column elements of the pth station in the synchronization error matrix (i.e., the sum of all elements in the pth row in the synchronization error matrix) is significantly higher than that of other stations, it indicates that the pth station is the "key interference source" of multi-station coordination. For example, due to high-frequency impact vibration, the dynamic error of the stamping station will be transmitted to the adjacent station through the mechanical structure.

[0114] Step S206: Determine the maximum value of the comprehensive interference intensities of all workstations, and determine the workstation corresponding to the maximum value as the interference source workstation.

[0115] Specifically, the maximum value of the comprehensive interference intensities of all workstations is determined, and the workstation corresponding to the maximum value is determined as the interference source workstation, thereby determining the interference source workstation.

[0116] Step S300: During the operation of the workstation robot, the end load error coefficient of each workstation is determined according to the relevant information of the robot end of different workstations.

[0117] Specifically, for multi-station stamping platforms, vibration sensors and temperature sensors are installed at key locations such as the punch crankshaft, mold guide column, and robot joints, and the sensors are used to collect vibration and temperature data of the punch and robot in real time. A safe operation threshold is set in advance. When the robot runs for a long time and the real-time vibration value or temperature value in the vibration and temperature data exceeds the safe operation threshold, no error compensation is required and the machine is shut down directly. Otherwise, it will operate normally.

[0118] During the normal operation of the multi-station stamping platform, due to the differences in the end loads of the manipulators at different stations (such as the weight of the stamping die and the clamping force of the workpiece), there is inconsistency in the end load inertia when the multi-stations are coordinated. For example, the end load inertia of the unloading station manipulator changes significantly due to the need to quickly release the workpiece. This inconsistency in the end load inertia will destroy the torque balance of the multi-axis collaborative control and lead to the accumulation of trajectory tracking errors. Therefore, during the working process of the station manipulator, error compensation is required to improve the control accuracy of the multi-station manipulator.

[0119] In order to perform error compensation, it is first necessary to obtain the relevant information of the manipulator end of different stations, which includes: the speed and distance in each motion direction obtained by disassembling the execution tasks of the manipulators at different stations, the motor current data when the manipulators at different stations perform tasks, the mass of the motion axis of the manipulators at different stations and the distance from the center of mass of the manipulator to the end, and the contact force data between the manipulators at different stations and the workpiece. Specifically, the tasks performed by the manipulators at each station are disassembled to obtain the speed and distance in each motion direction. The motor current is collected by the current sensor to obtain the motor current data when the manipulators at each station perform tasks. The total mass of each motion axis of the manipulators at each station (i.e., the mass of other parts of the manipulator except the end) and the distance from the center of mass of the manipulator to the end are obtained in advance. The contact force between the manipulator and the workpiece is collected by using the six-dimensional force sensor integrated in the end effector of the manipulator at each station, and the contact force data between the manipulator and the workpiece at each station are obtained.

[0120] Furthermore, in a possible implementation, if Figure 4 As shown, based on the relevant information of the manipulator end of different workstations, the end load error coefficient of each workstation is determined in the above step S300, including:

[0121] Step S301: Determine the ratio of the speed and distance in the current motion direction obtained by disassembling the execution task of the robot arm of each workstation to obtain a second ratio.

[0122] Specifically, determine the speed v and distance L in the current motion direction obtained by disassembling the execution task of the robot at each station o The ratio of The closer the end of the robot is to the workpiece and the faster it moves, the additional inertial force will inevitably be generated, and the larger the ratio will be.

[0123] Step S302: Determine the ratio of the motor current increase to the motor current fluctuation of the motor current data of the manipulator at each workstation when the manipulator is currently performing a task, and obtain a third ratio.

[0124] Specifically, for the end of the robotic arm, due to the position error caused by the load, additional inertial force and additional frictional force are inevitably generated. Among them, the frictional force is mostly generated by the fixed error on the working interface and basically performs horizontal movement, while the inertial force is the dynamic error conducted by the cantilever and mostly performs non-horizontal movement, which is more likely to interfere with other workstations. If the load inertia at the end of the workstation robotic arm suddenly increases, the motor current increases significantly at the same acceleration, that is, the greater the increase in the motor current ΔI. In a specific implementation, the increase in the motor current ΔI can be obtained by calculating the difference between the last current value and the first current in the motor current data during the execution of the current action of the workstation robotic arm, and using this difference as the exponent of the exponential function with the natural constant e as the base to obtain the value of the exponential function; when additional frictional force appears, the fluctuation of the motor current becomes larger, that is, the motor current fluctuation amount σ c becomes larger. In a specific implementation, the motor current fluctuation amount σ c can be obtained by calculating the variance of all current values in the motor current data during the execution of the action of the workstation robotic arm. Calculate the ratio of the increase in the motor current ΔI to the motor current fluctuation amount σ c and denote this ratio as the third ratio. The larger this third ratio, the greater the degree that the error is dominated by inertia. Therefore, this third ratio is also called the inertia dominance coefficient.

[0125] Step S303: Integrate the second ratio and the third ratio to determine the end load inertia of each workstation.

[0126] Specifically, integrate the second ratio and the third ratio to determine the end load inertia of each workstation. When the values of the second ratio and the third ratio are larger, it indicates that it is more likely that an external inertial force has caused a sudden increase in the load inertia at the end of the workstation robotic arm, and the corresponding value of the end load inertia is larger. In a specific implementation, calculate the product of the second ratio and the third ratio, and use this product as the end load inertia.

[0127] Step S304: Determine the self-rotational inertia of each workstation according to the mass of the moving axis of the robotic arm of each workstation and the distance from the center of mass of the robotic arm to the end.

[0128] Specifically, for the robotic arm of each workstation, determine its self-rotational inertia. When the mass of the moving axis of the robotic arm and the distance from the center of mass of the robotic arm to the end are larger, the self-rotational inertia of the robotic arm is larger. In a specific implementation, calculate the product of the mass of the moving axis of the robotic arm and the distance from the center of mass of the robotic arm to the end, and use this product as the self-rotational inertia of the corresponding workstation.

[0129] Step S305: Determine the load inertia ratio of each station according to the end load inertia and the load inertia ratio of each station.

[0130] Specifically, based on the end load inertia and the load inertia ratio of each station, determine the load inertia ratio of each station. A high load inertia ratio indicates that the end load inertia of this station has covered the normal moment of inertia of the manipulator itself, which is likely to cause a lag in the acceleration response controlled by the motor, and the acceleration dominated by the inertial force will generate more uncontrollable position errors. In a specific implementation, the standard normalization function is used to normalize the end load inertia and the load inertia ratio of each station respectively, and the ratio after normalizing the end load inertia and the load inertia ratio respectively is used as the load inertia ratio.

[0131] Step S306: Determine the contact force error of each station according to the difference between the current contact force and the desired contact force in the contact force data of the manipulator and the workpiece at each station.

[0132] Specifically, for the manipulator at each station, calculate the difference between the current contact force value and the desired contact force in the contact force data of the manipulator and the workpiece, and use this difference as the contact force error. It should be understood that in the case of inertial load, the contact force between the manipulator and the workpiece will only increase.

[0133] Step S307: Integrate the load inertia ratio and the contact force error to determine the end load error coefficient of each station.

[0134] Specifically, if the contact force error is larger and the load inertia ratio is high at this time, it is determined that the end contact force error is dominated by inertia at this time, which is likely to cause transmission errors to other stations. In a specific implementation, determine the product of the load inertia ratio and the contact force error corresponding to each station, and use this product as the contact force error.

[0135] By analyzing the error conditions caused by the end load differences of the manipulators at each station as described above, the end load error coefficient of each station can be accurately determined.

[0136] Step S400: Determine the cumulative error weight of each station according to the serial number difference between each station and the interference source station in the error transfer station sequence, and the difference between the end load error coefficients of each station and the interference source station.

[0137] Specifically, based on the error transfer station sequence, for each station, according to the sequence number difference between this station and the interference source station in the error transfer station sequence, and the end load error coefficients of each station and the interference source station, the cumulative error weight of each station is determined. When the sequence number difference between this station and the interference source station in the error transfer station sequence is smaller, it indicates that the error transfer is faster and the influence is greater. At this time, the weight that needs to be corrected for the cumulative error is larger. At the same time, the smaller the difference in the end load error coefficients between this station and the interference source station, it indicates that the end load of the interference source station has affected this station. Therefore, the cumulative error correction weight should also be larger.

[0138] Further, in a possible implementation, as Figure 5 shown, determining the cumulative error weight of each station in the above step S400 includes:

[0139] Step S401: Perform a negative correlation mapping on the difference in the sequence numbers of each station and the interference source station in the error transfer station sequence to obtain a sequence number difference mapping value.

[0140] Step S402: Determine the ratio of the end load error coefficients of each station and the interference source station to obtain a fourth ratio.

[0141] Step S403: Fuse the sequence number difference mapping value and the fourth ratio to obtain the cumulative error weight of each station.

[0142] Specifically, based on the sequence number difference mapping value and the fourth ratio, calculate the cumulative error weight of each station as follows:

[0143]

[0144] In the formula: β p represents the cumulative error weight of the p-th station; s max represents the sequence number of the interference source station in the error transfer station sequence; s p represents the sequence number of the p-th station in the error transfer station sequence; z p represents the end load error coefficient of the p-th station; z max represents the end load error coefficient of the interference source station; e represents the natural constant.

[0145] In the above formula, the smaller the absolute value of the difference in the sequence numbers of the p-th station and the interference source station in the error transfer station sequence, the faster the error transfer and the greater the influence. Conversely, the larger the absolute value of the difference in the sequence numbers, the smaller the cumulative error influence between the stations. In order to avoid a small number of multi-station manipulators, the square of the difference in the sequence numbers is amplified, and a negative correlation mapping is performed using the exponential function to obtain the sequence number difference mapping value The larger the square of the difference, the smaller the sequence number difference mapping value The smaller the value of represents the ratio of the end-load error coefficient of the p-th station to the end-load error coefficient of the interference source station, that is, the fourth ratio. The closer the numerator is to the denominator in the ratio, the more it means that the end-load of the interference source station has affected the p-th station. Therefore, the cumulative error correction weight is greater.

[0146] Step S500: Determine the initial cumulative error amount of each station according to the real-time position error of the manipulator of the interference source station and the difference between the asymmetric dynamic coupling strength of each station to the interference source station and the asymmetric dynamic coupling strength of the interference source station to each station in the synchronization error matrix.

[0147] Specifically, for each station, according to the real-time position error of the manipulator of the interference source station and in combination with the difference between the asymmetric dynamic coupling strength of each station to the interference source station and the asymmetric dynamic coupling strength of the interference source station to each station in the synchronization error matrix, the cumulative error amount of each station can be determined. This cumulative error amount refers to the cumulative transfer error generated by the interference source station to each station.

[0148] Further, in a possible implementation manner, as Figure 6 shown, determining the initial cumulative error amount of each station in the above step S500 includes:

[0149] Step S501: Determine the ratio of the asymmetric dynamic coupling strength of each station to the interference source station and the asymmetric dynamic coupling strength of the interference source station to each station in the synchronization error matrix to obtain the fifth ratio.

[0150] Step S502: Determine the integral of the product of the real-time position error of the manipulator of the interference source station and the fifth ratio with respect to time to obtain the initial cumulative error amount of each station.

[0151] Specifically, for each station, the initial cumulative error amount of this station is determined by the following formula:

[0152]

[0153] In the formula: ΔW p represents the initial cumulative error amount of the p-th station; represents the real-time position error of the manipulator of the interference source station, that is, the accumulated value of the real-time position errors of each motion axis of the manipulator. That is, the real-time position errors of each motion axis of the manipulator of the interference source station are accumulated in sequence and finally reach the end to form an end error. This end error is the real-time position error of each motion axis; ε p,max represents the asymmetric dynamic coupling strength of the p-th station to the interference source station in the synchronization error matrix; ε max,prepresents the asymmetric dynamic coupling strength of the interfering station in the synchronization error matrix to the p-th station; t represents time.

[0154] In the above formula, the asymmetric dynamic coupling strength ε of the p-th station in the synchronization error matrix to the interfering station p,max is multiplied by the fifth ratio of the asymmetric dynamic coupling strength of the interfering station to the p-th station and the real-time position error of the manipulator at the interfering station to obtain the transfer error generated by the interfering station to the p-th station. And represents the integral term of the transfer error over time, from which the initial cumulative error amount can be obtained. This initial cumulative error amount refers to the cumulative error occurring at the p-th station caused by the interfering station in the time sequence.

[0155] Step S600: Use the cumulative error weight of each station to perform weighted multiplication on the initial cumulative error amount, and finally obtain the cumulative error amount of each station.

[0156] Specifically, for each station, use the cumulative error weight of this station to perform weighted multiplication on the initial cumulative error amount of this station, and take the product obtained after multiplication as the final cumulative error amount of this station.

[0157] Step S700: Determine the error compensation value of each station according to the real-time position error and cumulative error amount of the manipulator at each station, and based on the error compensation value, perform compensation control on the manipulator at each station.

[0158] Specifically, for each station, combine the real-time position error of the manipulator at this station with the cumulative error amount of this station to obtain the error compensation value of this station. The corresponding calculation formula is:

[0159]

[0160] In the formula: W p represents the error compensation value of the p-th station; represents the real-time position error of the p-th station; e m represents the real-time position error of the m-th motion axis of the manipulator at the p-th station. This real-time position error is a numerical value; unm represents the total number of motion axes of the manipulator at the p-th station. In a specific implementation manner, num = 3; ΔW′ p represents the cumulative error amount of the p-th station.

[0161] According to the above method, the error compensation value of each station can be determined. This error compensation value includes the real-time position error It consists of two parts: the error value and the cumulative error amount. Among them, the cumulative error amount is obtained by adjusting the initial cumulative error amount through the cumulative error weight. When a certain station does not generate an error caused by large load inertia and is far from the interference source station, it is considered that this station does not need to correct the initial cumulative error too much. On the contrary, if this station generates an error caused by large load inertia and is close to the interference source station, it is necessary to use the cumulative error weight to increase the initial cumulative error accumulated over time.

[0162] Input the error compensation value of each determined station into the PID controller, and automatically generate a motor control instruction to perform compensation control on the manipulator of this station. Since this compensation control process belongs to the prior art, it will not be elaborated here.

[0163] Based on the same inventive concept, an embodiment of the present invention also provides a control system for a multi-station manipulator used in stamping a washing machine shell, as Figure 7 shown. This control system includes: a memory 701, a processor 702, and computer program code 703 stored in the memory 701 and running on the processor 702. Among them, when the processor 702 executes the computer program code 703, the system can execute any one of the control methods for the multi-station manipulator used in stamping a washing machine shell introduced above.

[0164] An embodiment of the present invention can divide the functions of the system according to the above method examples. For example, it can correspond to each functional module, or integrate two or more functions into one processing module. The above integrated modules can be implemented in the form of hardware. It should be noted that the division of modules in this embodiment is illustrative, only a logical function division, and there can be other division methods in actual implementation.

[0165] Based on the same inventive concept, an embodiment of the present invention also provides a computer program product. This computer program product includes: computer program code. When the computer program code runs on a computer, the computer executes any one of the control methods for the multi-station manipulator used in stamping a washing machine shell introduced above.

[0166] Based on the same inventive concept, an embodiment of the present invention also provides a computer-readable storage medium. This computer-readable storage medium stores computer program code. When the computer program code runs on a computer, the computer executes any one of the control methods for the multi-station manipulator used in stamping a washing machine shell introduced above.

[0167] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A control method for a multi-station manipulator used in stamping a washing machine housing, characterized in that, It includes the following steps: Using the station collaborative calibration experiment, construct a synchronous error matrix, where each element in the synchronous error matrix is the asymmetric dynamic coupling strength of one station to another station; According to the synchronous error matrix, determine the error transfer station sequence and the interference source station, and the error transfer station sequence is used to reflect the error transfer direction when different stations work together; During the operation of the station manipulator, determine the end load error coefficient of each station according to the relevant information of the end of the manipulator at different stations; According to the serial number difference between each station and the interference source station in the error transfer station sequence, and the difference between the end load error coefficients of each station and the interference source station, determine the cumulative error weight of each station; According to the real-time position error of the manipulator at the interference source station, and the difference between the asymmetric dynamic coupling strength of each station to the interference source station and the asymmetric dynamic coupling strength of the interference source station to each station in the synchronous error matrix, determine the initial cumulative error amount of each station; Use the cumulative error weight of each station to perform weighted multiplication on the initial cumulative error amount to finally obtain the cumulative error amount of each station; According to the real-time position error of the manipulator at each station and the cumulative error amount, determine the error compensation value of each station, and based on the error compensation value, perform compensation control on the manipulator at each station.

2. The control method of a multi-station manipulator for stamping the outer shell of a washing machine according to claim 1, characterized in that, Using the station collaborative calibration experiment to construct a synchronous error matrix includes: Applying a step acceleration excitation to different stations in the station collaborative calibration experiment, and obtaining the basic coupling coefficient between station i and station j under different step acceleration excitations; Based on the change of the basic coupling coefficient under adjacent step acceleration excitations, and combining the included angle between the force transfer direction of the manipulator at station i and the motion axis of the manipulator at station j, the structural arm length between station i and station j, and the equivalent mass and step acceleration excitation of the manipulator at station i, determine the asymmetric dynamic coupling coefficient of station i to station j; According to the asymmetric dynamic coupling coefficient and the distribution positions of different stations, determine the asymmetric dynamic coupling strength of the p-th station to the q-th station as the element in the p-th row and the q-th column of the synchronous error matrix.

3. The control method of a multi-station manipulator for stamping a washing machine shell according to claim 2, characterized in that, Obtaining the basic coupling coefficient between station i and station j under different step acceleration excitations includes: According to the position deviation between station i and station j, the structural arm length between station i and station j, and the position errors of each joint point of the manipulator at station i, determine the basic coupling coefficient between station i and station j under static conditions; Continuously apply a step acceleration excitation to station i in the station collaborative calibration experiment, and obtain the basic coupling coefficient between station i and station j under different step acceleration excitations.

4. The control method of a multi-station manipulator for stamping a washing machine shell according to claim 2, characterized in that, Determining the asymmetric dynamic coupling coefficient of station i to station j includes: Determine the change amount of the basic coupling coefficient under adjacent step acceleration excitations, perform linear fitting on the change amount to obtain a fitting straight line; Determine the slope of the fitting straight line to obtain the basic coupling coefficient change slope; Determine the asymmetric dynamic coupling coefficient of station \(i\) with respect to station \(j\) based on the variation slope of the base coupling coefficient, in combination with the included angle between the force transmission direction of the manipulator at station \(i\) and the motion axis of the manipulator at station \(j\), the structural arm length between stations \(i\) and \(j\), the equivalent mass of the manipulator at station \(i\), and the acceleration value of the step acceleration excitation.

5. The control method of a multi-station manipulator for stamping a washing machine outer shell according to claim 2, characterized in that, Determine the asymmetric dynamic coupling strength of the \(p\)-th station with respect to the \(q\)-th station as the element in the \(p\)-th row and \(q\)-th column of the synchronization error matrix, including: Sort all stations in the order from upstream to downstream of the production line to obtain the serial numbers of each station. Set the base elements at each position on the main diagonal of the synchronization error matrix to a first value, and set the base elements at other positions except the main diagonal of the synchronization error matrix to a second value, where the first value is greater than the second value. Determine the sum of the asymmetric dynamic coupling coefficient of the \(p\)-th station with respect to the \(q\)-th station and the base element in the \(p\)-th row and \(q\)-th column of the synchronization error matrix as the asymmetric dynamic coupling strength in the \(p\)-th row and \(q\)-th column of the synchronization error matrix, thereby obtaining the synchronization error matrix.

6. The control method of a multi-station manipulator for stamping a washing machine housing according to claim 5, characterized in that, Determine the error transmission station sequence, including: Determine the cumulative sum of the absolute values of the upper right triangular elements in the synchronization error matrix to obtain the forward transmission strength, and determine the cumulative sum of the absolute values of the lower left triangular elements in the synchronization error matrix to obtain the reverse transmission strength. Determine the ratio of the forward transmission strength to the reverse transmission strength to obtain a first ratio. If the first ratio is greater than the upper bound threshold, sort all stations in the order from upstream to downstream of the production line to obtain the error transmission station sequence; if the first ratio is less than the lower bound threshold, sort all stations in the order from downstream to upstream of the production line to obtain the error transmission station sequence. Otherwise, determine the cumulative sum of all column elements of each station in the synchronization error matrix to obtain the comprehensive interference strength of each station, and sort all stations in ascending order of the comprehensive interference strength of all stations to obtain the error transmission station sequence.

7. The control method of a multi-station manipulator for stamping a washing machine outer shell according to claim 5, characterized in that, Determine the interference source station, including: Determine the cumulative sum of all row elements of each station in the synchronization error matrix to obtain the comprehensive interference strength of each station. Determine the maximum value among the comprehensive interference strengths of all stations, and determine the station corresponding to the maximum value as the interference source station.

8. The control method of a multi-station manipulator for stamping the outer shell of a washing machine according to claim 1, characterized in that, The relevant information at the end of the manipulator includes at least: the speed and distance in each motion direction of the action obtained by disassembling the tasks executed by the manipulators at different stations, the motor current data when the manipulators at different stations execute tasks, the mass of the motion axis of the manipulators at different stations and the distance from the center of mass of the manipulator to the end, and the contact force data between the manipulators at different stations and the workpieces; determine the end load error coefficient of each station, including: Determine the ratio of the speed and distance in the current motion direction of the action obtained by disassembling the task executed by the manipulator at each station to obtain a second ratio. Determine the ratio of the motor current increase amount to the motor current fluctuation amount of the motor current data when the manipulator at each station is currently executing the task to obtain a third ratio. Fuse the second ratio and the third ratio to determine the end load inertia of each station; Determine the self-rotational inertia of each station according to the mass of the motion axis of the manipulator at each station and the distance from the center of mass of the manipulator to the end; Determine the load inertia ratio of each station according to the end load inertia of each station and the load inertia ratio; According to the difference between the current contact force and the desired contact force in the contact force data of the manipulator and the workpiece at each station, the contact force error of each station; Fuse the load inertia ratio and the contact force error to determine the end load error coefficient of each station.

9. The control method of a multi-station manipulator for stamping the outer shell of a washing machine according to claim 1, characterized in that, Determine the cumulative error weight of each station, including: Perform a negative correlation mapping on the difference between the serial numbers of each station and the interference source station in the error transfer station sequence to obtain a serial number difference mapping value; Determine the ratio of the end load error coefficients of each station and the interference source station to obtain a fourth ratio; Fuse the serial number difference mapping value and the fourth ratio to obtain the cumulative error weight of each station.

10. The control method of a multi-station manipulator for stamping the outer shell of a washing machine according to claim 1, characterized in that, Determine the initial cumulative error amount of each station, including: Determine the ratio of the asymmetric dynamic coupling strength of each station to the interference source station and the asymmetric dynamic coupling strength of the interference source station to each station in the synchronous error matrix to obtain a fifth ratio; Determine the integral over time of the product of the real-time position error of the manipulator at the interference source station and the fifth ratio to obtain the initial cumulative error amount of each station.

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