Method for establishing and applying full-speed-domain absolute position sample library

Abstract

The invention is suitable for the technical field of position measurement, and provides a full-speed-domain absolute position sample library establishment and application method for rotor position measurement, and the establishment method comprises the steps: randomly generating a plurality of groups of sample library construction parameters based on an established rotor position detection platform; acquiring position measurement sample data through the rotor position detection platform according to the sample library construction parameters, and constructing multiple groups of absolute position sample libraries according to the position measurement sample data; obtaining the measurement precision and the measurement efficiency of each operation of the absolute position sample library; with the measurement precision and the measurement efficiency as targets, the multi-target grey wolf optimization algorithm is operated for multiple times to obtain the optimal solution of the sample library construction parameters; and obtaining a final sample library construction optimization parameter according to the optimal solution of the sample library construction parameter, and constructing a final sample library. According to the method, the exposure time of the camera can be optimized under the condition of different mover movement speeds, so that the influence on the sample image quality is reduced; and the position measurement precision of the rotor is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of position measurement, and particularly relates to the position measurement of a linear motor mover. Specifically, a method for establishing and applying an absolute position sample library in the full speed range for mover position measurement is disclosed. Background Art

[0002] Due to advantages such as simple structure, strong adaptability, and high acceleration, high-precision servo linear motors are widely used in fields such as transportation and precision manufacturing, such as high-speed maglev trains, laser engraving, etc. The control accuracy of a linear motor affects the operating accuracy of a machine, and the real-time performance and measurement accuracy of the position measurement of the linear motor mover directly affect the control accuracy of the linear motor. Therefore, the research on the real-time high-precision measurement of the linear motor mover position is of great significance to the linear motor servo control system.

[0003] The method for measuring the position of a linear motor mover based on a sample library can well eliminate the influence of cumulative error on the measurement accuracy during the long-stroke measurement process, thereby improving the detection accuracy of the position of the large-stroke linear motor mover. In a linear motor servo system, both measurement accuracy and efficiency directly affect the control accuracy of the servo system. In the method for measuring the position of a linear motor mover based on a sample library, not only the algorithm itself determines the measurement efficiency and accuracy, but also the sampling accuracy of the sample image and the size of the sample image greatly affect the efficiency of the measurement method.

[0004] The existing research on image displacement measurement methods in the field of linear motor displacement measurement mainly focuses on the performance improvement of adjacent frame displacement measurement. The accurate measurement of the adjacent frame displacement of the linear motor mover has been successfully achieved, but the problem of cumulative error transmission in long-stroke measurement has not been considered, and cumulative error is the key factor affecting the displacement measurement accuracy of long-stroke linear motors. In this regard, a measurement method based on sample library matching (Patent Application No.: CN202310672462.7) is provided. By scanning a reference image with a line-scan camera, multiple groups of sample sequences with different sampling intervals are constructed.

[0005] However, the construction of the sample library in this method is only based on the basic requirements of precision measurement. Such simple parameter settings result in a large number of unnecessary calculations in the search process of the algorithm, thus consuming valuable computing time and seriously affecting the efficiency of the matching algorithm. Increasing the sampling interval to improve the search efficiency can reduce the amount of calculation, but this often sacrifices measurement accuracy, which goes against the original intention of improving measurement accuracy, and it is necessary to make improvements. Summary of the Invention

[0006] The object of the present invention is to provide a method for establishing and applying an absolute position sample library for full-speed range mover position measurement, aiming to further improve the measurement accuracy and feedback real-time performance of existing image measurement methods and solve the problems mentioned in the background technology. This method can balance the relationship between measurement accuracy and measurement efficiency, improve the measurement efficiency on the premise of ensuring measurement accuracy, and reduce the calculation redundancy in the measurement process.

[0007] The present invention is implemented as follows. A method for establishing an absolute position sample library for full-speed range mover position measurement, the method comprising the following steps:

[0008] Based on the established mover position detection platform, randomly generate several groups of sample library construction parameters;

[0009] According to the sample library construction parameters, obtain position measurement sample data through the mover position detection platform, and construct multiple groups of absolute position sample libraries according to the position measurement sample data;

[0010] Obtain the measurement accuracy and measurement efficiency of each run of the absolute position sample library;

[0011] Taking the measurement accuracy and measurement efficiency as the objectives, run the multi-objective grey wolf optimization algorithm multiple times to obtain the optimal solution of the sample library construction parameters;

[0012] According to the optimal solution of the sample library construction parameters, obtain the final optimized sample library construction parameters, and construct the final sample library as the absolute position sample library for full-speed range.

[0013] Further, in the step of obtaining the measurement accuracy and measurement efficiency of each run of the absolute position sample library, through the improved SURF feature point matching algorithm, obtain the measurement accuracy and measurement efficiency of each run of the absolute position sample library. It should be noted that the image obtained by the line array camera shooting the target source image is the target image.

[0014] Further, the method further comprises:

[0015] Based on the mover position detection platform, list the camera acquisition frequency f, the mover movement speed v, and the image length g as parameters to be optimized, improve the SURF feature point matching algorithm, and obtain the improved SURF feature point matching algorithm.

[0016] Further, after the step of randomly generating several groups of sample library construction parameters based on the established mover position detection platform, the method further comprises:

[0017] Calibrate the parameters of the mover position detection platform to determine that the mover position detection platform is built according to the specified configuration.

[0018] Another object of the present invention is to provide a full-speed range absolute position sample library application method for mover position measurement, and the method includes:

[0019] Based on the established mover position detection platform, obtain the real-time target image during the operation of the mover;

[0020] Match the real-time target image through the full-speed range absolute position sample library;

[0021] Output the measured position of the mover according to the matching result.

[0022] Further, the method further includes:

[0023] Obtain the actual position of the mover;

[0024] Compare the error between the actual position and the obtained measured position, and analyze the operating state of the linear motor.

[0025] Based on the full-speed range absolute position sample library for image matching, the present invention can optimize the camera exposure time under different mover movement speed conditions to reduce the impact on the quality of the sample image. At the same time, by adjusting the sample interval, the redundant calculation in the sample library search algorithm is reduced, and the over-simplification of the search process is avoided, thereby significantly improving the measurement efficiency on the premise of ensuring the measurement accuracy. Description of the Drawings

[0026] Figure 1 It is a flowchart of a full-speed range absolute position sample library establishment method for mover position measurement provided by an embodiment of the present invention;

[0027] Figure 2 It is a structural block diagram of a mover position detection platform provided by an embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of the xy axis of the target source image shooting plane in an embodiment of the present invention;

[0029] Figure 4 It is a schematic diagram of the construction of the sample library in an embodiment of the present invention;

[0030] Figure 5 It is a principle flowchart of a full-speed range absolute position sample library establishment method for mover position measurement provided by an embodiment of the present invention;

[0031] Figure 6 It is a flowchart of a full-speed range absolute position sample library application method for mover position measurement provided by an embodiment of the present invention. Detailed Embodiments

[0032] In order to make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] Glossary: SURF (Speeded-Up Robust Features) is a feature point detection and description algorithm used in computer vision, which is widely applied to tasks such as image matching, object recognition, and 3D reconstruction.

[0034] In fact, in the linear motor mover position detection method based on the absolute position sample library, the measurement accuracy is affected by many conditions, such as the accuracy of the selected matching algorithm, the measurement environment, and the sampling accuracy of the sample images in the sample library. The sampling accuracy of the sample library not only affects the measurement efficiency but also has an important impact on the measurement accuracy. In order to balance the measurement accuracy and efficiency of the algorithm, the present invention optimizes the construction parameters of the sample library to adapt to a specific measurement algorithm and the actual measurement environment, so as to obtain the full-speed domain absolute position sample library parameters adapted to the algorithm; during image matching, the measurement efficiency can be improved on the premise of ensuring the measurement accuracy, and the calculation redundancy during the measurement process can be reduced.

[0035] Figure 1 It is a flowchart of a method for establishing a full-speed domain absolute position sample library for mover position measurement provided by an embodiment of the present invention; Figure 2 It is a structural block diagram of a mover position detection platform provided by an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the xy axis of the target source image shooting plane in an embodiment of the present invention; Figure 4 It is a schematic diagram of the construction of the sample library in an embodiment of the present invention; Figure 5 It is a principle flowchart of a method for establishing a full-speed domain absolute position sample library for mover position measurement provided by an embodiment of the present invention.

[0037] In one embodiment, a method for establishing a full-speed domain absolute position sample library for mover position measurement is proposed, which specifically may include the following steps S101 to S105;

[0038] S101, based on the established mover position detection platform, randomly generate several groups of sample library construction parameters;

[0039] Such as Figure 2As shown in the figure, the mover position detection platform includes: a permanent magnet synchronous linear motor (hereinafter referred to as the linear motor), a line array camera, a target source image, a light source, a linear motor control module, and a computer; the light source, the linear motor control module are electrically connected to the computer, and the computer can control the light source to irradiate the target source image to provide the light required for the line array camera to take pictures, and the linear motor control module controls the operation of the permanent magnet synchronous linear motor; the images taken by the line array camera can be transmitted to the computer.

[0040] Among them, the linear motor control module is an electronic device or system used to control the operation of the linear motor, mainly to drive the linear motor and achieve precise motion control; generally includes a controller, a driver, a feedback system, a power supply module, a communication interface, and a human-machine interface; Controller: Responsible for receiving instructions from the upper computer (such as PLC, PC), generating control signals; implementing motion control algorithms, such as position control, speed control, acceleration control, etc. Driver: Converts the control signal into the current and voltage required by the motor to drive the linear motor to operate; usually uses PWM (pulse width modulation) technology to adjust the output current; provides protection functions such as overcurrent, overvoltage, and overheating. Feedback system: Uses sensors (such as grating rulers, magnetic grating rulers, encoders, etc.) to detect the actual position and speed of the motor; transmits the feedback signal to the controller to achieve closed-loop control and improve motion accuracy. Power supply module: Provides stable power for the control module and the linear motor; selects appropriate power supply voltage and current according to the motor power demand. Communication interface: Supports communication with the upper computer or other devices, such as EtherCAT, CAN, RS-485, Modbus, etc.; realizes remote control and data exchange. Human-machine interface: Provides an operation interface to facilitate users to set parameters, monitor the status, and debug the system.

[0041] In this embodiment, after the step of randomly generating several groups of sample library construction parameters based on the established mover position detection platform, the method further includes:

[0042] Calibrate the parameters of the mover position detection platform to determine that the mover position detection platform is built according to the specified configuration;

[0043] For example: First, place the linear motor on the linear motor base, set the length direction of the target source image parallel to the movement direction of the mover, and moreover, the frame of the target image needs to be larger than the stroke of the mover. The shooting surface of the target source image is parallel and aligned with the movement axis of the linear motor in the x-axis direction. At the same time, the y-axis of the shooting surface should be perpendicular to the placement surface of the linear motor base. The line array camera is fixed on the linear motor mover (i.e., the mover) and moves together with the linear motor mover. The absolute position sample library is mainly completed by the cooperation of the linear motor and the line array camera.

[0044] S102. Obtain position measurement sample data through the mover position detection platform according to the sample library construction parameters, and construct multiple groups of absolute position sample libraries based on the position measurement sample data;

[0045] Among them, the absolute position sample library takes into account both the influence of the camera exposure time on the quality of the sample image at different mover movement speeds and the influence of the sample interval on the efficiency of the sample library search algorithm. It is necessary to avoid data redundancy and prevent over-simplification.

[0046] The sample library construction parameters include the movement speed of the mover, the shooting frequency of the linear array camera, and the interval between adjacent sample libraries.

[0047] When constructing the absolute position sample library, first construct a single sample library, and then change the movement speed of the mover to obtain sample libraries at different speeds.

[0048] Specifically, the constructed single sample library is a series of sample images. The construction process of a single sample library is as follows:

[0049] Place the mover at the starting end of the linear motor. When the mover of the linear motor starts to move towards the other end at a constant speed v, the linear array camera also starts shooting at a fixed frequency f at the same time;

[0050] When the mover of the linear motor moves every 1 / f time, the linear array camera takes a picture of the target image once;

[0051] Therefore, in a single sample library, the interval between adjacent sample libraries is d. Where d = v / f. In this way, the measurement accuracy of the sample library is d.

[0052] To construct the full-speed-range absolute position sample library, it is necessary to repeat the construction process of the single sample library in the previous paragraph, change the movement speed of the mover, and repeat this process to construct enough sample libraries at different speeds to form a sample array library, which is called the full-speed-range absolute position sample library.

[0053] Exemplarily, the linear array camera is fixed on the mover of the linear motor and moves linearly along the guide rail direction together with the mover. During the construction of the sample library, the linear array camera collects the one-dimensional gray-scale signal of the target image through shooting at a fixed frequency f to construct the image sample library. f mainly affects the accuracy and quantity of the sample library. And the sample array library needs to be composed of sample libraries at different movement speeds.

[0054] S103. Obtain the measurement accuracy and measurement efficiency of each operation of the absolute position sample library;

[0055] Exemplarily, to improve the measurement accuracy and efficiency of the linear motor mover position detection and ensure the balance between measurement accuracy and efficiency, an improved SURF feature point matching algorithm is introduced, with the measurement algorithm accuracy and efficiency as the objective functions, and the target parameters to be optimized are input to quickly realize the optimization of the sample library construction parameters.

[0056] Exemplarily, based on the mover position detection platform, the camera acquisition frequency f, the mover movement speed v, and the image length g are listed as the parameters to be optimized, and part or all of the integral image, Hessian matrix, and scale space of the improved SURF feature point matching algorithm are improved to obtain the improved SURF feature point matching algorithm. In this embodiment, the scale space is mainly adjusted to realize the improvement of the algorithm.

[0057] S104, with the measurement accuracy and efficiency as the goals, run the multi-objective grey wolf optimization algorithm multiple times to obtain the optimal solution of the sample library construction parameters;

[0058] In this step, the multi-objective grey wolf optimization algorithm introduces an archive mechanism and an improved alpha wolf selection method to handle the Pareto optimal solutions in multi-objective problems. The multi-objective grey wolf optimization algorithm stores and retrieves the most suitable non-dominated solutions during the optimization process and selects the alpha wolf from the archive by means of roulette to maintain population diversity and improve algorithm performance.

[0059] S105, according to the optimal solution of the sample library construction parameters, obtain the final optimized parameters for sample library construction, and construct the final sample library as the full-speed range absolute position sample library.

[0060] The application of the full-speed range absolute position sample library realizes high-precision mover position measurement. It ensures a high degree of matching between the sample library and the selected algorithm, thus significantly improving the rationality and efficiency of the sample library construction process. By introducing the SRUF feature point matching algorithm, different sample library construction parameters can be systematically analyzed and evaluated to find the best parameter combination to adapt to specific measurement requirements and conditions. By this method, while ensuring measurement accuracy, the measurement speed can be increased, the cost can be reduced, providing strong technical support for the precise control and application of linear motors.

[0061] In this embodiment, the method introduces the SRUF feature point matching algorithm and combines the advantages of the multi-objective grey wolf optimization algorithm to achieve the global optimization of the parameters for constructing the sample library. This global optimization strategy not only improves the measurement accuracy of the linear motor mover position but also effectively enhances the measurement efficiency. By combining these two algorithms, the present invention can optimize the camera exposure time under different mover movement speed conditions to reduce the impact on the quality of the sample images. At the same time, by adjusting the sample interval, the redundant calculations in the sample library search algorithm are reduced, and the over-simplification of the search process is avoided, thereby significantly improving the measurement efficiency on the premise of ensuring the measurement accuracy.

[0062] In another embodiment, as Figure 6 shown, a method for applying a full-speed-range absolute position sample library for mover position measurement includes:

[0063] S201, based on the established mover position detection platform, obtain the real-time target image during the mover operation;

[0064] In this embodiment, the line array camera is fixed on the linear motor mover and follows the mover to capture the target source image fixed in front of the mover in real time; the collected sequence image signals are transmitted to the computer to obtain the target image information, and the actual displacement of the mover is obtained through analysis by the computer system.

[0065] S202, match the real-time target image through the full-speed-range absolute position sample library;

[0066] S203, output the measured position of the mover according to the matching result.

[0067] In this embodiment, the method of this embodiment further includes: obtaining the actual position of the mover; comparing the error between the actual position and the obtained measured position, and analyzing the operating state of the linear motor.

[0068] This embodiment can optimize the camera exposure time under different mover movement speed conditions to reduce the impact on the quality of the sample images. At the same time, by adjusting the sample interval, the redundant calculations in the sample library search algorithm are reduced, and the over-simplification of the search process is avoided, thereby significantly improving the measurement efficiency on the premise of ensuring the measurement accuracy.

[0069] It should be understood that although the steps in the flowcharts of the embodiments of the present invention are shown sequentially according to the indications of the arrows, these steps are not necessarily executed sequentially in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in each embodiment may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least a part of other steps or sub-steps or stages of other steps.

[0070] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

[0071] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for establishing a full-speed domain absolute position sample library for mover position measurement, characterized in that: The method comprises: Based on the established mover position detection platform, several groups of sample library construction parameters are randomly generated; Acquiring position measurement sample data through the mover position detection platform according to the sample library construction parameters, and constructing multiple groups of absolute position sample libraries according to the position measurement sample data; Obtain the measurement accuracy and measurement efficiency of each absolute position sample library run; With measurement accuracy and efficiency as the goal, the multi-objective Grey Wolf Optimization Algorithm was run multiple times to obtain the optimal solution for the sample library construction parameters; According to the optimal solution of the sample library construction parameters, the final sample library construction optimization parameters are obtained, and the final sample library is constructed as the full-speed domain absolute position sample library.

2. The method according to claim 1, characterized in that In the step of obtaining the measurement accuracy and measurement efficiency of each absolute position sample library operation, the measurement accuracy and measurement efficiency of each absolute position sample library operation are obtained by using an improved SURF feature point matching algorithm.

3. The method according to claim 2, characterized in that The method further comprises: Based on the mover position detection platform, the camera acquisition frequency f, the mover movement speed v and the image length g are listed as parameters to be optimized, and the SURF feature point matching algorithm is improved to obtain an improved SURF feature point matching algorithm.

4. The method according to claim 1, characterized in that: After the step of randomly generating several groups of sample library construction parameters based on the established mover position detection platform, the method further includes: The parameters of the mover position detection platform are calibrated to ensure that the mover position detection platform is built according to the specified configuration.

5. A method for applying a full-speed domain absolute position sample library for mover position measurement, characterized in that: The method comprises: Based on the established mover position detection platform, obtain the real-time target image of the mover during operation; Matching the real-time target image by using a full-speed domain absolute position sample library obtained by any method according to claims 1-4; The measured position of the mover is output according to the matching result.

6. The method according to claim 5, characterized in that The method further comprises: Get the actual position of the mover; The error between the actual position and the obtained measured position is compared to analyze the running state of the linear motor.

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