Cross table laser precision compensation method and system

Abstract

The present application relates to the technical field of positioning accuracy of cross table, and discloses a kind of cross table laser precision compensation method and system, comprising: using laser interferometer to carry out position measurement to cross table;Using linear interpolation algorithm to calculate the predicted positioning error of current target point;The predicted positioning error obtained by calculation is superimposed to control loop to generate pre-correction instruction;Synthesize control instruction and drive servo motor, realize the precision compensation of cross table.Through laser interferometer, the position measurement of cross table is realized, the actual movement position of workbench can be obtained, the accurate prediction of geometric error is realized, and then the predicted error is superimposed to control loop, the problems that existing static pitch compensation cannot be dynamically adjusted, compensation precision is low and adaptability to complex working conditions is poor are solved, the real-time compensation of multi-dimensional geometric error of cross table is realized, and the positioning accuracy of workbench is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of positioning accuracy technology for cross-shaped worktables, and specifically to a laser accuracy compensation method and system for cross-shaped worktables. Background Technology

[0002] The positioning accuracy of a cross-shaped worktable primarily depends on the manufacturing precision of the ball screw and guide rails, as well as the performance of the closed-loop servo system. However, in actual operation, mechanical wear accumulates over time, residual stress generated during assembly is difficult to completely eliminate, and thermal deformation during worktable operation, along with environmental factors such as temperature fluctuations and vibrations, can all lead to various geometric errors in the cross-shaped worktable. These errors include positioning errors, straightness errors, and angular errors such as pitch, yaw, and roll. These errors directly affect the positioning accuracy of the worktable, thereby limiting the machining or motion accuracy of machine tools and other equipment equipped with the worktable.

[0003] In existing technologies, the compensation methods for the aforementioned errors mostly employ static pitch compensation, which involves pre-setting a fixed error compensation table in the machine tool controller to compensate for the pitch error of the worktable. However, this static compensation method has significant drawbacks. It cannot adapt to dynamic changes during worktable operation, such as error drift caused by temperature rise or error fluctuations caused by load changes. Furthermore, it can only compensate for pitch errors in a single dimension and cannot cover multi-dimensional spatial geometric errors such as positioning errors, straightness errors, and angular errors, resulting in limited compensation effectiveness. Summary of the Invention

[0004] This invention provides a laser precision compensation method and system for a cross-shaped worktable to solve the problem that the error of existing cross-shaped worktables cannot be accurately adjusted.

[0005] In a first aspect, the present invention provides a laser accuracy compensation method for a cross-shaped worktable, comprising: A laser interferometer is used to measure the position of the cross-shaped worktable along the X and Y axes. The measured real-time position coordinate data is written into the motion control card at a preset control cycle to establish a feedback path based on the actual position of the end of the cross-shaped worktable. The system retrieves the pre-stored forward motion error mapping table and reverse motion error table, selects the corresponding error mapping table according to the current motion direction of the cross-shaped worktable, and searches for two adjacent calibration points (X) in the selected error mapping table based on the target command position. low E low ) and (X high E high ), where X low ≤Target command position <X high The prediction and positioning error C of the current target point is calculated using a linear interpolation algorithm. pred ; ; Among them, X cmd The target instruction location; The calculated predicted positioning error C pred The pre-correction command is superimposed onto the control loop to generate a pre-correction command, and the real-time feedback value X from the laser interferometer is read. laser ; The motion control software reads the written laser actual position feedback value and obtains the target command position set by the current motion command. It calculates the position deviation e according to the formula e = target command position - laser actual position feedback. Synthesize control commands and drive servo motors to achieve precision compensation of the cross-shaped worktable.

[0006] Beneficial effects: By using a laser interferometer to measure the X and Y axes of the cross-shaped worktable and establish a feedback path for the actual end position, the limitations of traditional encoder feedback are overcome, enabling the acquisition of the actual movement position of the worktable. At the same time, relying on the forward and reverse motion error mapping table combined with the linear interpolation algorithm to calculate the predicted positioning error, accurate prediction of comprehensive geometric errors such as return error is achieved. Furthermore, by superimposing the predicted error into the control loop, calculating the position deviation, and synthesizing the control command, the complete process solves the problems of existing static pitch compensation being unable to be dynamically adjusted, having low compensation accuracy, and poor adaptability to complex working conditions. This achieves real-time compensation for multi-dimensional geometric errors of the cross-shaped worktable, significantly improving the positioning accuracy of the worktable.

[0007] In one optional implementation, the preset control period is 100 μs.

[0008] Beneficial effects: Setting the preset control cycle to 100μs, this high-frequency control cycle enables the writing of real-time laser position coordinate data without delay. This allows the motion control card to acquire the worktable position information in a very short time interval, ensuring the real-time and accurate position feedback. This enables the control system to respond promptly to changes in the worktable's motion, avoiding compensation lag caused by data acquisition delays, and further improving the accuracy and effectiveness of dynamic compensation.

[0009] In one alternative implementation, the pre-correction instruction is generated by first calculating the target position X for pre-correction. cmd_comp =X cmd -C pred , where X cmd To determine the target instruction location, then set X... cmd_comp Substitute the values ​​into the position deviation calculation formula to complete the deviation calculation.

[0010] Beneficial effects: Through X cmd_comp =X cmd -C predThe method generates pre-correction instructions, incorporating the predicted positioning error into the target position correction in advance. This ensures that the subsequent deviation calculation is based on the pre-corrected target position, eliminating the need for the controller to handle the original large error. Instead, it only needs to adjust the remaining uncompensated small deviations, effectively improving the dynamic response speed of the control system. At the same time, it makes error compensation more proactive, reducing the position deviation of the worktable from the source and improving the accuracy of compensation.

[0011] In one alternative implementation, the position deviation e=X is calculated. cmd_comp -X laser .

[0012] Beneficial effect: The formula for calculating position deviation is determined as e=X cmd_comp -X laser Using the pre-corrected target position as a reference, the deviation is calculated by combining the actual position feedback value collected by the laser interferometer. This calculation method accurately reflects the instantaneous difference between the actual position of the worktable and the pre-corrected target position, providing a precise deviation basis for the controller to output drive signals. It avoids compensation errors caused by reference deviation, making the subsequent control command synthesis more in line with the actual motion requirements of the worktable and improving the accuracy of compensation.

[0013] In one alternative implementation, the control command is executed by the controller calculating the output U based on the position deviation e. pid According to U final =U pid +K×C pred Generate final control command U final , where K is the feedforward gain coefficient.

[0014] Beneficial effects: Through U final =U pid +K×C pred The final control command is generated in a way that combines the controller's regular output with the feedforward compensation based on the prediction error to form a feedforward-feedback composite control mode. This mode retains the controller's closed-loop adjustment capability for real-time deviations and converts the prediction error into a driving compensation through the feedforward gain coefficient K, thereby achieving early cancellation of impending errors. This solves the problem that traditional single control can only passively correct errors and improves the error compensation efficiency and accuracy of the control system.

[0015] In one alternative implementation, the feedforward gain coefficient K is used to convert the predicted error into a reverse drive command, pre-driving the cross stage to counteract the impending error.

[0016] Beneficial effects: The role of the feedforward gain coefficient K is clarified as converting the prediction error into a reverse drive command and pre-driving the cross stage. This clarifies the physical meaning and function of the coefficient. By adjusting the coefficient, the pre-drive force can be precisely controlled. The compensation intensity can be flexibly matched according to the movement conditions and mechanical characteristics of the stage, achieving precise cancellation of the prediction error. This effectively avoids the problem of the stage moving too far or too far, and eliminates the accuracy loss caused by directional dependence.

[0017] In one optional implementation, the predicted positioning error C pred This refers to the error predicted by the system during the movement of the cross-shaped worktable, and includes comprehensive geometric error information including return error.

[0018] Beneficial effect: Clearly defines the predicted positioning error C pred The comprehensive geometric error information, including return error, enables the compensation value to fully reflect various geometric errors caused by mechanical wear, assembly stress, thermal deformation, and changes in movement direction during the movement of the cross-shaped worktable. This solves the problem that existing compensation methods cannot comprehensively compensate for multi-dimensional and multi-type errors. It allows the pre-correction and control command synthesis based on the compensation value to fully offset various motion errors of the worktable, greatly improving the comprehensiveness and effectiveness of the compensation.

[0019] Secondly, the present invention also provides a laser accuracy compensation system for a cross-shaped worktable, applied to the aforementioned laser accuracy compensation method for a cross-shaped worktable, comprising: Laser interferometer, data acquisition module, data communication module, motion control card, servo motor and main control unit; The laser interferometer is set to correspond to the X-axis and Y-axis of the cross stage, and is used to measure the X-axis and Y-axis of the cross stage and collect real-time position coordinate data. The data acquisition module and data communication module are respectively connected to the laser interferometer and the motion control card, and are used to transmit the real-time position coordinate data acquired by the laser interferometer to the motion control card; The main control unit is connected to the motion control card, has built-in motion control software, and pre-stores a forward motion error mapping table and a reverse motion error table. The motion control card is connected to the servo motor and is used to receive control commands from the main control unit and drive the servo motor to operate. The servo motor is connected to the cross-shaped worktable and is used to drive the movement of the cross-shaped worktable.

[0020] Beneficial effects: Through the modular collaborative design of the laser interferometer, data acquisition module, data communication module, motion control card, servo motor, and main control unit, a closed-loop control of the entire process from position data acquisition, transmission, error calculation to control command output and table drive is realized. The laser interferometer accurately acquires position data, the main control unit has built-in software and pre-stores an error mapping table to realize error calculation, and the motion control card and servo motor complete the command execution. Each module has a clear division of labor and close connection, providing a hardware carrier and system support for the compensation method. It solves the problem that traditional laser interferometers are only used for offline detection and are not deeply integrated with the machine tool control system. It realizes the deep integration of laser compensation function and cross table control system, ensuring the smooth realization of real-time dynamic compensation.

[0021] In one optional implementation, the motion control card is configured with a memory address or register for writing the actual laser position feedback value acquired by the laser interferometer.

[0022] Beneficial effects: Configuring a dedicated memory address or register for the motion control card to write the actual laser position feedback value allows the real-time position data acquired by the laser interferometer to be directly and without delay stored at the designated position on the motion control card. This bypasses the traditional encoder feedback channel, avoiding delays or loss of data during transmission and storage, ensuring the timeliness and accuracy of the position feedback data, providing hardware support for the motion control software to quickly read data and calculate position deviations, and improving the response speed of the entire compensation system.

[0023] In one optional implementation, the motion control card has a built-in control module, which is used to calculate and output a drive signal based on the position deviation or the deviation corresponding to the pre-corrected target position and transmit it to the servo motor.

[0024] Beneficial effects: A dedicated control module is set up in the motion control card. This module is specifically used to calculate and output drive signals based on the position deviation or the deviation corresponding to the pre-corrected target position. It realizes the integrated processing of deviation calculation and drive signal output, reduces the transmission links of signals between different components, reduces signal transmission delay and interference, and enables the drive signal to be transmitted to the servo motor quickly and accurately. This allows the servo motor to respond to the instructions of the control system in a timely manner and accurately drive the cross table to move, further improving the control accuracy and response efficiency of the compensation system. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a flowchart of the laser precision compensation method for the cross-shaped worktable of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The following is combined with Figure 1 The following describes embodiments of the present invention.

[0029] According to an embodiment of the present invention, in one aspect, a laser accuracy compensation method for a cross-shaped worktable is provided, comprising: A laser interferometer is used to measure the position of the cross-shaped worktable along the X and Y axes. The measured real-time position coordinate data is written into the motion control card at a preset control cycle to establish a feedback path based on the actual position of the end of the cross-shaped worktable. Specifically, the preset control cycle is 100μs. Setting the preset control cycle to 100μs, this high-frequency control cycle enables the writing of real-time laser position coordinate data without delay, allowing the motion control card to acquire the worktable position information in a very short time interval. This ensures the real-time and accurate position feedback, enabling the control system to respond promptly to changes in the worktable's movement, avoiding compensation lag caused by data acquisition delays, and further improving the accuracy and effect of dynamic compensation.

[0030] The system retrieves the pre-stored forward motion error mapping table and reverse motion error table, selects the corresponding error mapping table according to the current motion direction of the cross-shaped worktable, and searches for two adjacent calibration points (X) in the selected error mapping table based on the target command position. low E low ) and (X high E high ), where X low ≤Target command position <X high The prediction and positioning error C of the current target point is calculated using a linear interpolation algorithm.pred ; ; Among them, X cmd The target instruction location; The calculated predicted positioning error C pred The pre-correction command is superimposed onto the control loop to generate a pre-correction command, and the real-time feedback value X from the laser interferometer is read. laser ; The method for generating pre-correction instructions is to first calculate the target position X for pre-correction. cmd_comp =X cmd -C pred , where X cmd To determine the target instruction location, then set X... cmd_comp Substitute the values ​​into the position deviation calculation formula to complete the deviation calculation. (Using X...) cmd_comp =X cmd -C pred The method generates pre-correction instructions, incorporating the predicted positioning error into the target position correction in advance. This ensures that the subsequent deviation calculation is based on the pre-corrected target position, eliminating the need for the controller to handle the original large error. Instead, it only needs to adjust the remaining uncompensated small deviations, effectively improving the dynamic response speed of the control system. At the same time, it makes error compensation more proactive, reducing the position deviation of the worktable from the source and improving the accuracy of compensation.

[0031] The motion control software reads the written laser actual position feedback value and simultaneously obtains the target command position set by the current motion command. It then calculates the position deviation e according to the formula e = target command position - laser actual position feedback. Specifically, the position deviation e = X cmd_comp -X laser The formula for calculating position deviation is defined as e=X. cmd_comp -X laser Using the pre-corrected target position as a reference, and combining the actual position feedback value collected by the laser interferometer, the deviation is calculated. This calculation method accurately reflects the instantaneous difference between the actual position of the worktable and the pre-corrected target position, providing a precise deviation basis for the controller to output drive signals. This avoids compensation errors caused by reference deviation, allowing subsequent control command synthesis to better match the actual motion requirements of the worktable and improving the accuracy of compensation. A high-speed data acquisition card is used to realize data transmission between the laser interferometer and the motion control card. A dedicated hardware interface is selected as the communication and data transmission carrier between the laser interferometer and the motion control card to complete the real-time position coordinate data writing operation.

[0032] The system synthesizes control commands and drives the servo motor to achieve precision compensation for the cross-shaped worktable. The control command method is as follows: the controller calculates and outputs U based on the position deviation e. pid According to U final =Upid +K×C pred Generate final control command U final , where K is the feedforward gain coefficient.

[0033] Through U final =U pid +K×C pred The final control command is generated in a way that combines the controller's regular output with the feedforward compensation based on the prediction error to form a feedforward-feedback composite control mode. This mode retains the controller's closed-loop adjustment capability for real-time deviations and converts the prediction error into a driving compensation through the feedforward gain coefficient K, thereby achieving early cancellation of impending errors. This solves the problem that traditional single control can only passively correct errors and improves the error compensation efficiency and accuracy of the control system.

[0034] By using a laser interferometer to measure the X and Y axes of the cross-shaped worktable and establish a feedback path for the actual end position, the limitations of traditional encoder feedback are overcome, enabling the acquisition of the actual movement position of the worktable. Simultaneously, relying on the forward and reverse motion error mapping table combined with a linear interpolation algorithm to calculate the predicted positioning error, accurate prediction of comprehensive geometric errors such as return error is achieved. Furthermore, by superimposing the predicted error into the control loop, calculating the position deviation, and synthesizing the control command, the complete process solves the problems of existing static pitch compensation being unable to be dynamically adjusted, having low compensation accuracy, and poor adaptability to complex working conditions. This enables real-time compensation for multi-dimensional geometric errors of the cross-shaped worktable, significantly improving the positioning accuracy of the worktable.

[0035] Specifically, the system's pre-stored X-axis error mapping table contains the command position (X, unit: mm) and the corresponding error value (E, unit: μm) calibration point. If the current cross-shaped worktable is moving in the forward direction, the forward motion error mapping table is retrieved, and the target command position X is... cmd =80mm, find the adjacent calibration point X in the mapping table. low =50mm, E low =+1.2μm and X high =100mm, E high =+2.1μm, satisfying X low ≤X cmd <X high .

[0036] The predicted positioning error C is calculated using a linear interpolation algorithm. pred Substituting the above calibration point data into the formula, we can calculate: C pred =1.74μm.

[0037] The calculation result is the predicted positioning error at the target command position of 80mm. It means that when the worktable moves forward at this position, it will actually travel 1.74μm less. The system can use this value to calculate the pre-corrected target position and achieve accurate error prediction.

[0038] In one embodiment, the feedforward gain coefficient K is used to convert the predicted error into a reverse drive command, pre-driving the cross-shaped worktable to offset the impending error. By clarifying that the function of the feedforward gain coefficient K is to convert the predicted error into a reverse drive command and pre-drive the cross-shaped worktable, the physical meaning and function of this coefficient are clearly defined. Adjusting this coefficient allows for precise control of the pre-drive force, flexibly matching the compensation intensity according to the worktable's motion conditions and mechanical characteristics, achieving precise offsetting of the predicted error, effectively avoiding the problem of the worktable moving too far or too little, and eliminating the accuracy loss caused by direction dependence.

[0039] The feedforward gain coefficient K is usually close to 1. For different motion conditions of the cross-shaped worktable, the specific adjustment range and implementation method of K value are given so that the compensation effect matches the actual motion state of the worktable.

[0040] When the cross-shaped worktable is in a low-speed, light-load motion condition, the error caused by mechanical wear and load deformation is relatively small. Adjusting the K value to 0.95~1.0, the feedforward compensation amount is close to the predicted positioning error, which can accurately offset the small geometric error of the worktable and avoid position fluctuations caused by overcompensation. When the cross-shaped worktable is in high-speed, heavy-load motion, the error caused by thermal deformation and load stress increases, and the inertial error of the worktable motion increases. Adjusting the K value to 0.90~0.95 and appropriately reducing the feedforward compensation amount, combined with the closed-loop feedback adjustment of the PID controller, can balance the error cancellation effect and the stability of the control system, and prevent the worktable from "going too far" due to inertia. When the cross-shaped worktable performs a reverse reversal motion, the return error is the main source of error. Adjusting the K value to 1.0~1.05 and specifically increasing the feedforward compensation can effectively offset the mechanical backlash and return error during the reversal process, and eliminate the accuracy loss caused by the direction dependence.

[0041] The K value can be adjusted by setting parameters through the motion control software of the main control unit. It supports both manual adaptation and automatic adjustment. Manual adjustment allows the operator to set a fixed value according to the on-site working conditions, while automatic adjustment allows the system to adjust the K value in real time according to the movement speed of the workbench and load detection data, further improving the adaptability of the compensation system to complex working conditions.

[0042] In one embodiment, the predicted positioning error C predThis refers to the error predicted by the system during the movement of the cross-shaped worktable, including comprehensive geometric error information such as return error. The predicted positioning error C is clearly defined. pred The comprehensive geometric error information, including return error, enables the compensation value to fully reflect various geometric errors caused by mechanical wear, assembly stress, thermal deformation, and changes in movement direction during the movement of the cross-shaped worktable. This solves the problem that existing compensation methods cannot comprehensively compensate for multi-dimensional and multi-type errors. It allows the pre-correction and control command synthesis based on the compensation value to fully offset various motion errors of the worktable, greatly improving the comprehensiveness and effectiveness of the compensation.

[0043] According to an embodiment of the present invention, in another aspect, a laser accuracy compensation system for a cross-shaped worktable is also provided, applied to the above-described laser accuracy compensation method for a cross-shaped worktable, comprising: Laser interferometer, data acquisition module, data communication module, motion control card, servo motor and main control unit; The laser interferometer is set to correspond to the X-axis and Y-axis of the cross stage, and is used to measure the X-axis and Y-axis of the cross stage and collect real-time position coordinate data. The data acquisition module and data communication module are respectively connected to the laser interferometer and the motion control card, and are used to transmit the real-time position coordinate data acquired by the laser interferometer to the motion control card; The main control unit is connected to the motion control card, has built-in motion control software, and pre-stores a forward motion error mapping table and a reverse motion error table. The motion control card is connected to the servo motor and is used to receive control commands from the main control unit and drive the servo motor to operate. The servo motor is connected to the cross-shaped worktable and is used to drive the movement of the cross-shaped worktable.

[0044] Through the modular collaborative design of laser interferometer, data acquisition module, data communication module, motion control card, servo motor and main control unit, a closed-loop control of the entire process from position data acquisition, transmission, error calculation to control command output and table drive is realized. The laser interferometer accurately acquires position data, the main control unit has built-in software and pre-stores an error mapping table to realize error calculation, and the motion control card and servo motor complete the command execution. Each module has a clear division of labor and close connection, providing a hardware carrier and system support for the compensation method. It solves the problem that traditional laser interferometers are only used for offline detection and are not deeply integrated with the machine tool control system. It realizes the deep integration of laser compensation function and cross table control system, ensuring the smooth realization of real-time dynamic compensation.

[0045] In one embodiment, the motion control card is configured with a memory address or register for writing the actual laser position feedback value acquired by the laser interferometer. Configuring a dedicated memory address or register for the motion control card to write the actual laser position feedback value allows the real-time position data acquired by the laser interferometer to be directly and without delay stored at a designated location on the motion control card. This bypasses the traditional encoder feedback channel, avoiding delays or data loss during transmission and storage, ensuring the timeliness and accuracy of the position feedback data. This provides hardware support for the motion control software to quickly read data and calculate position deviations, improving the response speed of the entire compensation system.

[0046] In one embodiment, the motion control card has a built-in control module. This control module calculates and outputs a drive signal based on the position deviation or the deviation corresponding to the pre-corrected target position, and transmits it to the servo motor. By integrating the deviation calculation and drive signal output into a dedicated control module within the motion control card, the transmission links between different components are reduced, signal transmission delay and interference are minimized, and the drive signal can be transmitted to the servo motor quickly and accurately. This allows the servo motor to respond promptly to the control system's commands and precisely drive the cross-shaped worktable, further improving the control accuracy and response efficiency of the compensation system.

[0047] The hardware module of the laser precision compensation system for the cross stage of this invention first completes the initial connection. The laser interferometer is positioned corresponding to the X and Y axes of the cross stage. The data acquisition / communication module establishes a communication link between the laser interferometer and the motion control card. The main control unit pre-stores the forward and reverse motion error mapping tables and completes the parameter initialization of the motion control software, PID controller, and feedforward gain coefficient K. The memory address / register of the motion control card is ready, and the transmission connection between the servo motor and the cross stage is in a ready-to-drive state.

[0048] After the system initiates the motion control task, the overall working process is executed in the following steps: Target command input: The main control unit inputs the target command position X of the cross-shaped worktable to the motion control card. cmd At the same time, determine the current direction of movement of the worktable (forward / reverse); Prediction error calculation: The main control unit retrieves the corresponding error mapping table based on the direction of motion, using X... cmd To find adjacent calibration points for the query key, the predicted positioning error C is calculated using a linear interpolation algorithm. pred ; Pre-correction target position generation: The main control unit presses X. cmd_comp =X cmd Cpred Calculate the pre-corrected target position and complete the correction of the target position's preceding error. Real-time position acquisition and writing: The laser interferometer performs synchronous position measurement on the X and Y axes of the worktable. The acquired real-time position coordinate data is written to the specified memory address / register of the motion control card through the data acquisition / communication module at a preset control cycle of 100μs. Position deviation calculation: The motion control software reads the actual laser position feedback value X from the motion control card. laser According to e=X cmd_comp X laser Calculate the current position deviation; Control command synthesis and output: The motion control card's control module calculates and outputs U based on the position deviation e using a PID controller. pid Press U again final =U pid +K×C pred Generate final control command U final And transmit the drive signal to the servo motor; Worktable drive and compensation: After receiving the drive signal, the servo motor drives the cross worktable to move according to the final control command, realizing real-time compensation of position accuracy.

[0049] The entire working process forms a closed-loop control system encompassing data acquisition, error prediction, target correction, deviation calculation, command output, and drive compensation. The real-time position feedback of the laser interferometer overcomes the limitations of traditional encoders. The forward and reverse error mapping table combined with the linear interpolation algorithm enables accurate prediction of multi-dimensional geometric errors. The feedforward-feedback composite control mode solves the problem of insufficient dynamics in traditional static compensation. The coordinated cooperation of various hardware modules and software algorithms ultimately achieves a significant improvement in the positioning accuracy of the cross stage.

[0050] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A laser accuracy compensation method for a cross-shaped worktable, characterized in that, include: A laser interferometer is used to measure the position of the cross-shaped worktable along the X and Y axes. The measured real-time position coordinate data is written into the motion control card at a preset control cycle to establish a feedback path based on the actual position of the end of the cross-shaped worktable. The system retrieves the pre-stored forward motion error mapping table and reverse motion error table, selects the corresponding error mapping table according to the current motion direction of the cross-shaped worktable, and searches for two adjacent calibration points (X) in the selected error mapping table based on the target command position. low E low ) and (X high E high ), where X low ≤Target command position <X high The prediction and positioning error C of the current target point is calculated using a linear interpolation algorithm. pred ; ； Among them, X cmd The target instruction location; The calculated predicted positioning error C pred The pre-correction command is superimposed onto the control loop to generate a pre-correction command, and the real-time feedback value X from the laser interferometer is read. laser ; The motion control software reads the written laser actual position feedback value and obtains the target command position set by the current motion command. It calculates the position deviation e according to the formula e = target command position - laser actual position feedback. Synthesize control commands and drive servo motors to achieve precision compensation of the cross-shaped worktable.

2. The laser accuracy compensation method for the cross-shaped worktable according to claim 1, characterized in that, The preset control period is 100μs.

3. The laser accuracy compensation method for the cross-shaped worktable according to claim 1, characterized in that, The method for generating pre-correction instructions is to first calculate the target position X for pre-correction. cmd_comp =X cmd -C pred , where X cmd To determine the target instruction location, then set X... cmd_comp Substitute the values ​​into the position deviation calculation formula to complete the deviation calculation.

4. The laser accuracy compensation method for the cross-shaped worktable according to claim 1, characterized in that, Calculate the positional deviation e=X cmd_comp -X laser .

5. The laser accuracy compensation method for the cross-shaped worktable according to claim 1, characterized in that, The control command method is as follows: the controller calculates the output U based on the position deviation e. pid According to U final =U pid +K×C pred Generate final control command U final , where K is the feedforward gain coefficient.

6. The laser accuracy compensation method for the cross-shaped worktable according to claim 1, characterized in that, The feedforward gain coefficient K is used to convert the predicted error into a reverse drive command, which drives the cross stage in advance to counteract the impending error.

7. The laser accuracy compensation method for the cross-shaped worktable according to claim 1, characterized in that, The predicted positioning error C pred This refers to the error predicted by the system during the movement of the cross-shaped worktable, and includes comprehensive geometric error information including return error.

8. A laser precision compensation system for a cross-shaped worktable, applied to the laser precision compensation method for a cross-shaped worktable as described in any one of claims 1 to 7, characterized in that, include: Laser interferometer, data acquisition module, data communication module, motion control card, servo motor and main control unit; The laser interferometer is set to correspond to the X-axis and Y-axis of the cross stage, and is used to measure the X-axis and Y-axis of the cross stage and collect real-time position coordinate data. The data acquisition module and data communication module are respectively connected to the laser interferometer and the motion control card, and are used to transmit the real-time position coordinate data acquired by the laser interferometer to the motion control card; The main control unit is connected to the motion control card, has built-in motion control software, and pre-stores a forward motion error mapping table and a reverse motion error table. The motion control card is connected to the servo motor and is used to receive control commands from the main control unit and drive the servo motor to operate. The servo motor is connected to the cross-shaped worktable and is used to drive the movement of the cross-shaped worktable.

9. The laser precision compensation system for the cross-shaped worktable according to claim 8, characterized in that, The motion control card is equipped with a memory address or register, which is used to write the actual laser position feedback value collected by the laser interferometer.

10. The laser precision compensation system for the cross-shaped worktable according to claim 8, characterized in that, The motion control card has a built-in control module, which is used to calculate and output a drive signal based on the position deviation or the deviation corresponding to the pre-corrected target position and transmit it to the servo motor.

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