Closed-loop control electric multi-axis platform system with echelon complementary correction and operation method

Abstract

The invention discloses a closed-loop control electric multi-axis platform system with echelon complementary correction and an operation method. The closed-loop control electric multi-axis platform system comprises an electric multi-axis platform, a plurality of grating rulers, a plurality of original point positioning modules, a system control module and a power supply module, the electric multi-axis platform is composed of a plurality of electric single-axis platforms in different axial directions, the grating rulers are installed on the electric single-axis platforms in different axial directions respectively, and the original point positioning module is arranged close to reset zero positions of the grating rulers. The system control module is used for receiving an operation instruction and displaying or broadcasting platform operation data, an operation result and other information needing to be displayed, and the system control module comprises a communication module and a control core; the power supply module supplies power to the whole platform system, and compared with the prior art, under closed-loop control of the control module, good initial positioning accuracy is obtained; and after the closed-loop correction at the operation tail section of the current work task is carried out, echelon complementary correction is carried out again, so that higher positioning precision is obtained.

Description

Technical Field

[0001] The present invention relates to the field of control systems, and in particular to a closed-loop controlled electric multi-axis platform system with step-by-step complementary correction and an operation method thereof. Background Art

[0002] Currently, many inspections and precision machining require the use of multi-axis high-precision mobile platforms. The objects to be inspected, objects to be processed, or inspection tools, machining tools and other platform loaders are mounted on the load platform of the multi-axis high-precision mobile platform and moved in multiple axes.

[0003] In order to ensure the accuracy of detection or processing, the precise positioning of the platform load in motion is particularly critical. At present, common multi-axis platforms are generally composed of precision single-axis platforms, and rely on the mechanical accuracy of the single-axis platform itself and the positioning of the drive system itself to ensure the positioning accuracy during operation. Although some axis platforms have been equipped with auxiliary positioning equipment, they are only used for monitoring or single-axis platform motion positioning verification, and do not participate in motion regulation and control.

[0004] The usual operation mode is to use the current position as the origin and the target position as the end point, distribute the parameters to be moved to each single-axis platform drive system, generate the movement parameters of each single-axis platform, and execute them through each single-axis platform drive system. After the execution is completed, it is considered that the platform load has been moved into place. This method is heavily dependent on the accuracy of each single-axis platform itself and the control of the electric actuator on the error. It lacks other positioning and correction means to re-position and confirm the final position of the platform load.

[0005] Some closed-loop control systems only perform closed-loop control on the motion control of each single-axis platform separately, without performing complementary correction on the motion control results between the single-axis platforms. Although the accuracy is improved, there are still some shortcomings.

[0006] In addition, affected by the mechanical errors of each single-axis platform, after continuous and multiple movements, the impact of the final platform's cumulative error on the final result will increase, and the discreteness of the positioning target result will increase. Although the zeroing of the motion mechanism position will eliminate some of the cumulative error, the error caused by mechanical wear cannot be eliminated. Summary of the invention

[0007] The purpose of the present invention is to address the problem that the existing multi-axis loading platform relies heavily on the accuracy of the single-axis platform itself and lacks other positioning and correction means. In addition, the error caused by the wear of the single-axis platform itself cannot be eliminated. To address this problem, a closed-loop control electric multi-axis platform system and operation method with step-by-step complementary correction are proposed. In order to achieve the above object, the present invention adopts the following technical solution: A closed-loop controlled electric multi-axis platform system with step-by-step complementary correction comprises an electric multi-axis platform, a plurality of grating rulers, a plurality of origin positioning modules, a system control module, a power supply module and a host computer platform; the electric multi-axis platform is composed of a plurality of electric single-axis platforms with different axial directions, the plurality of grating rulers are respectively installed on the plurality of electric single-axis platforms with different axial directions, a loading platform is arranged on the topmost electric single-axis platform, the origin positioning module is arranged close to the reset zero position of the grating ruler, the system control module is used for receiving operation instructions, displaying or broadcasting platform operation data and operation results and other information that needs to be displayed, the system control module comprises a communication module and a control core, the electric single-axis platform, the grating ruler and the origin positioning module are all connected to the system control module; the power supply module supplies power to the entire platform system.

[0008] As a further preferred embodiment of the present invention, a plurality of electric single-axis platforms with different axial directions are vertically fixedly connected in sequence by bolts, and the electric single-axis platform includes a stepper motor driver, a driving stepper motor, and a precision mechanical platform.

[0009] As a further preferred embodiment of the present invention, the plurality of electric single-axis platforms with different axial directions include a maximum of 3 linear motion axis platforms and a maximum of 3 arc motion axis platforms.

[0010] A method for operating a closed-loop controlled electric multi-axis platform system with step-by-step complementary correction comprises the following steps: S1. System installation and debugging are completed, the circuit is powered on and self-test is completed; S2. Place the target object for subsequent work on the loading platform and fix it. The origin positioning module attached to each electric single-axis platform in the system works to determine the zero point of each electric single-axis platform in the system. S3, inputting operation instructions and parameters into the system control module through the host computer platform; S4, the system control module generates initial operation parameters according to the operation instructions and parameters combined with the current zero point positioning data, and sends driving instructions to the stepper motor drivers of the electric single-axis platforms of different axes through the communication module to drive the motors to work and move the moving parts of each electric single-axis platform to the position specified by the parameters; S5, the system closed-loop control works, and the measured data of the grating ruler is compared with the theoretical value of each electric single-axis platform. If there is a deviation, the system control module controls the electric single-axis platform with the deviation to make corrections, completing the first stage of correction; S6. After the first stage of calibration is completed, the grating ruler data attached to each electric single-axis platform in the system is obtained, combined with the zero point data, and the difference between the current actual position and the theoretical position is calculated with the final position as the target; S7, preset the error range, and judge whether the difference is within the error range; if the difference is within the error range, then it meets the requirements and the correction adjustment is completed; S8. If the difference exceeds the system accuracy requirement, the second stage of calibration is performed; S9, the mechanical position in the system is locked by the stepper motor driving each electric single-axis platform; S10. After the work is completed, the system control module controls the mobile loading platform to reset to the zero position after startup, and removes the platform load for proper disposal. The system completes the control of the platform load position adjustment operation process.

[0011] As a further preferred embodiment of the present invention, the second stage correction includes: When linear motion is in progress, based on the difference calculated by S6, the final position is taken as the target and the current position is taken as the starting point, and the three-axis linear complementary algorithm is used to calculate the correction operating parameters of the linear motion axis platform; The electric single-axis platform that needs to be calibrated moves according to the recalculated calibration operating parameters to obtain the calibration result; When the arc moves, based on the correction result of the linear motion, the final position is taken as the target and the current position is taken as the starting point. The complementary filtering algorithm is used to fuse the angle value of the arc motion axis platform to obtain the correction variable. The electric single-axis platform that needs to be corrected corrects the arc motion axis platform according to the calculated correction variables; the second stage of correction is completed.

[0012] The closed-loop controlled electric multi-axis platform system and operation method with step-by-step complementary correction proposed by the present invention have the following beneficial effects compared with the prior art: 1. The present invention uses a grating ruler for non-contact measurement, effectively reducing the error caused by mechanical wear during use; 2. During the work task, after the platform load is placed and fixed on the load platform, the origin positioning module first performs zero point positioning, which can effectively reduce the impact of cumulative errors on the current work; 3. Mechanical reset plus the electronic positioning processing of the origin positioning module can more accurately locate the actual initial position of the platform load, providing an accurate starting point for subsequent work; 4. During operation, the system operates under the closed-loop control of the control module, and the closed-loop control can obtain better initial positioning accuracy; 5. After the closed-loop calibration at the end of the current task, a step-by-step complementary calibration is performed to obtain higher positioning accuracy; 6. When improving the original open-loop multi-axis platform, the present invention uses a grating ruler and a communication module for improvement. Compared with the original improvement scheme of matching the axis platform with appropriate accuracy, the cost-plus price ratio is less than 10%, and the original system control hardware does not need to be upgraded, which greatly reduces the equipment improvement cost; 7. The closed-loop control and correction processing in the present invention is automatically processed by the control system, which does not increase the difficulty of manual operation and does not require operation training, thereby reducing the improvement cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of a closed-loop controlled electric multi-axis platform system with step-by-step complementary correction according to the present invention; Figure 2 It is a schematic diagram of the combination of electric single-axis platforms with different axes; Figure 3 The present invention relates to a flow chart of a closed-loop controlled electric multi-axis platform system operation method with step-by-step complementary correction.

[0014] The meanings of the reference numerals in the figure are: 1. host computer platform, 2. system control module, 3. electric multi-axis platform, 4. grating ruler, 5. origin positioning module, 6. power module, 301. X-axis platform, 302. Y-axis platform, 303. Z-axis platform, 304. θz-axis platform, 305. θy-axis platform, 306. θx-axis platform. DETAILED DESCRIPTION

[0015] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] The present invention relates to a closed-loop controlled electric multi-axis platform system with step-by-step complementary correction. After the platform load is fixed on the system load platform, zero-point positioning is performed to improve the cumulative error. During the movement of the system mechanical structure, the movement of each single-axis platform is non-contactly measured by adding a grating ruler to each single-axis platform, and the measurement result is added to the motion control of the multi-axis platform to realize closed-loop control, and initially obtain higher positioning accuracy and smaller discreteness of the execution result. Then, higher positioning accuracy is obtained through step-by-step complementary correction of the position of each axis platform in the system.

[0017] Embodiment 1: Combination Figure 1-2 A closed-loop controlled electric multi-axis platform 3 system with step-by-step complementary correction includes an electric multi-axis platform 3, a plurality of grating rulers 4, a plurality of origin positioning modules 5, a system control module 2, a power supply module 6 and a host computer platform 1.

[0018] The electric multi-axis platform 3 is composed of several electric single-axis platforms with different axial directions. The electric single-axis platforms with different axial directions are vertically fixedly connected in sequence by bolts, and can be vertically combined in sequence according to the platform load-bearing conditions of each axis platform. A loading platform is arranged on the electric single-axis platform at the top. The electric single-axis platforms with different axial directions include up to 3 linear motion axis platforms and up to 3 arc motion axis platforms; the linear motion axis platform includes an X-axis platform 301, a Y-axis platform 302 and a Z-axis platform 303; the arc motion axis platform includes a θz-axis platform 304, a θy-axis platform 305 and a θx-axis platform 306. The electric single-axis platform includes a stepper motor driver, a driving stepper motor and a precision mechanical platform. Each electric single-axis platform is equipped with a stepper motor and a matching stepper motor driver for driving its own moving parts. Each electric single-axis platform operates independently under the control of the system control module 2, and does not affect each other during operation.

[0019] The X-axis platform 301 and the Y-axis platform 302 are two identical electric single-axis platforms. When the platforms are assembled, the Y-axis platform 302 is rotated 90° counterclockwise and then installed on the X-axis platform 301. The parameters of the X-axis platform 301 and the Y-axis platform 302 are the same, and the moving range is ±100mm, and the moving range in the Z-axis direction is ±8mm. A grating ruler 4 is added to measure the displacement. After the closed-loop control of the step-by-step complementary correction is realized, the repeat positioning accuracy in the X-axis direction and the Y-axis direction is ≤±0.5μm, and the repeat positioning accuracy in the Z-axis direction is ≤±0.2μm.

[0020] The θy-axis platform 305 and the θx-axis platform 306 are two identical electric single-axis platforms. When installed, the θx-axis platform 306 is rotated 90° counterclockwise and then installed on the θy-axis platform 305; the parameters of the θy-axis platform 305 and the θx-axis platform 306 are the same, and the travel range is ±10°, and the travel range of the θz-axis platform 304 is ±5°. After adding a grating ruler 4 to measure the displacement and realizing closed-loop control of step-by-step complementary correction, the repeatability of the θx-axis rotation angle and the θy-axis rotation angle is ±0.001°, and the repeatability of the z-axis rotation angle is ≤0.002°.

[0021] The plurality of grating rulers 4 are respectively installed on a plurality of electric single-axis platforms with different axes, and work in conjunction with the movable platform of each electric single-axis platform. The grating ruler 4 measures the position change of the electric single-axis platform and feeds back the data to the system control system.

[0022] The origin positioning module 5 is arranged close to the reset zero position of the grating ruler 4 to position the moving reference zero point of each electric single-axis platform, and determines the zero point position of each electric single-axis platform together with the grating ruler 4 before the measurement starts.

[0023] The system control module 2 contains human-computer interaction, which is used to receive operation instructions, display or broadcast platform operation data and operation results and other information that needs to be displayed. The system control module 2 includes a communication module and a control core, wherein the communication module is connected to the electric single-axis platform, the grating ruler 4 and the origin positioning module 5; data interaction is performed; the communication module also communicates with external devices such as the host computer platform 1; the control core is responsible for adjusting the calculation and operation control of the whole machine.

[0024] The power module 6 supplies power to the entire platform system and is the system power control module. It is connected to the AC220V50Hz mains power. After processing, it provides the required power to each component according to the power voltage and power of each part in the system, and undertakes the main EMC protection function of the system.

[0025] The host computer platform 1 is a stand-alone Windows platform software, which is used by operators to operate the machine within a certain distance when they cannot directly operate the human-machine interaction device of the system itself; it also has auxiliary functions such as operation and equipment operation status data storage, operation log generation, etc. This software is not required and is an optional component.

[0026] Embodiment 2: Combination Figure 3 , a method for operating a closed-loop controlled electric multi-axis platform 3 system with step-by-step complementary correction, comprising the following steps: S1. System installation and debugging are completed, the circuit is powered on and self-test is completed.

[0027] S2. Place the target object for subsequent work on the loading platform and fix it. The origin positioning module attached to each electric single-axis platform in the system works to determine the zero point of each electric single-axis platform in the system.

[0028] The system is powered on and started. After the system completes self-test in a no-load state, the object to be tested is fixed above the loading platform of the θx-axis platform 306 located at the top of the entire system.

[0029] S3. Input operation instructions and parameters to the system control module 2 through the host computer platform 1.

[0030] S4. The system control module 2 generates initial operation parameters according to the operation instructions and parameters combined with the current zero point positioning data, and sends driving instructions to the stepper motor drivers of the electric single-axis platforms in different axes through the communication module to drive the motors to move the moving parts of each electric single-axis platform to the position specified by the parameters.

[0031] S5. The system works in a closed-loop control mode. The measured data of the grating ruler is compared with the theoretical values ​​of each electric single-axis platform. If there is a deviation, the system control module controls the electric single-axis platform with the deviation to make corrections, thus completing the first stage of correction.

[0032] The system moves the platform load as needed. The working order is that after receiving the moving command and corresponding parameters, the system generates control commands and parameters through the built-in control module to move the platform load to the target position of the command parameters. After moving to the command position, each single-axis electric load platform, according to the measurement data of the grating ruler 4, if there is a discrepancy, uses a closed-loop control method to control the movement of the moving part in the platform until the moving length measured by the grating ruler is consistent with the length that should be moved in theory. The six single-axis platforms complete a position correction independently.

[0033] S6. After the first stage of calibration is completed, the data of the grating ruler 4 attached to each electric single-axis platform in the system is obtained, combined with the zero point data, and the difference between the current actual position and the theoretical position is calculated with the final position as the target.

[0034] S7. Preset the error range and determine whether the difference is within the error range; if the difference is within the error range, it meets the requirements and the correction adjustment is completed.

[0035] S8. If the difference exceeds the system accuracy requirement, proceed to the second stage of calibration.

[0036] When linear motion occurs, based on the difference calculated by S6, the final position is taken as the target and the current position is taken as the starting point. The three-axis linear complementary algorithm is used to calculate the correction operating parameters of the linear motion axis platform, that is, the operating parameters of the X-axis, Y-axis, and Z-axis, and the corresponding mechanical adjustment actions are completed in a closed-loop manner.

[0037] The electric single-axis platform that needs to be calibrated is moved according to the recalculated calibration operating parameters to obtain a calibration result.

[0038] When the arc motion occurs, based on the correction result of the linear motion, with the final position as the target and the current position as the starting point, the complementary filtering algorithm is used to fuse the angle value of the arc motion axis platform, that is, the three axial parameters of the θx axis, θy axis, and θz axis are fused and calculated to obtain the correction variable.

[0039] The electric single-axis platform that needs to be corrected corrects the arc motion axis platform according to the calculated correction variables; the second stage of correction is completed.

[0040] S9. The mechanical position in the system is locked by the stepper motor driving each electric single-axis platform.

[0041] S10. After the work is completed, the system control module 2 controls the mobile loading platform to reset to the zero position after startup, and removes the platform load for proper disposal. The system completes the control of the platform load position adjustment operation process.

[0042] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A closed-loop controlled electric multi-axis platform system with step-by-step complementary correction, characterized in that: It includes an electric multi-axis platform, a plurality of grating rulers, a plurality of origin positioning modules, a system control module, a power supply module and a host computer platform; the electric multi-axis platform is composed of a plurality of electric single-axis platforms with different axial directions, a loading platform is arranged on the topmost electric single-axis platform, a plurality of grating rulers are respectively installed on a plurality of electric single-axis platforms with different axial directions, the origin positioning module is arranged close to the reset zero position of the grating ruler, the system control module is used for receiving operation instructions, displaying or broadcasting platform operation data and operation results and other information that needs to be displayed, the system control module includes a communication module and a control core, the electric single-axis platform, the grating ruler and the origin positioning module are all connected to the system control module; the power supply module supplies power to the entire platform system.

2. A closed-loop controlled electric multi-axis platform system with step-by-step complementary correction according to claim 1, characterized in that: Several electric single-axis platforms with different axial directions are vertically fixedly connected in sequence by bolts, and the electric single-axis platform includes a stepper motor driver, a driving stepper motor, and a precision mechanical platform.

3. A closed-loop controlled electric multi-axis platform system with step-by-step complementary correction according to claim 1, characterized in that: The electric single-axis platforms of several different axial directions include at most 3 linear motion axis platforms and at most 3 arc motion axis platforms.

4. A method for operating a closed-loop controlled electric multi-axis platform system with step-by-step complementary correction according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. System installation and debugging are completed, the circuit is powered on and self-test is completed; S2. Place the target object for subsequent work on the loading platform and fix it. The origin positioning module attached to each electric single-axis platform in the system works to determine the zero point of each electric single-axis platform in the system. S3, inputting operation instructions and parameters into the system control module through the host computer platform; S4, the system control module generates initial operation parameters according to the operation instructions and parameters combined with the current zero point positioning data, and sends driving instructions to the stepper motor drivers of the electric single-axis platforms of different axes through the communication module to drive the motors to work and move the moving parts of each electric single-axis platform to the position specified by the parameters; S5, the system closed-loop control works, and the measured data of the grating ruler is compared with the theoretical value of each electric single-axis platform. If there is a deviation, the system control module controls the electric single-axis platform with the deviation to make corrections, completing the first stage of correction; S6. After the first stage of calibration is completed, the grating ruler data attached to each electric single-axis platform in the system is obtained, combined with the zero point data, and the difference between the current actual position and the theoretical position is calculated with the final position as the target; S7, preset the error range, and judge whether the difference is within the error range; if the difference is within the error range, it meets the requirements and the correction adjustment is completed; S8. If the difference exceeds the system accuracy requirement, the second stage of calibration is performed; S9, the mechanical position in the system is locked by the stepper motor driving each electric single-axis platform; S10. After the work is completed, the system control module controls the mobile loading platform to reset to the zero position after startup, and removes the platform load for proper disposal. The system completes the control of the platform load position adjustment operation process.

5. The method for operating a closed-loop controlled electric multi-axis platform system with step-by-step complementary correction according to claim 4, characterized in that: The second stage of correction includes: When linear motion is in progress, based on the difference calculated by S6, the final position is taken as the target and the current position is taken as the starting point, and the three-axis linear complementary algorithm is used to calculate the correction operating parameters of the linear motion axis platform; The electric single-axis platform that needs to be calibrated moves according to the recalculated calibration operating parameters to obtain the calibration result; When the arc moves, based on the correction result of the linear motion, the final position is taken as the target and the current position is taken as the starting point. The complementary filtering algorithm is used to fuse the angle value of the arc motion axis platform to obtain the correction variable. The electric single-axis platform that needs to be corrected corrects the arc motion axis platform according to the calculated correction variables; the second stage of correction is completed.

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