Precision optimization method and system for five-axis movement mechanism and storage medium

Abstract

The invention discloses a precision optimization method for a five-axis movement mechanism. The precision optimization method comprises the following steps: S1, calibrating the pixel ratio of a camera and the rotation angle of a CCD (Charge Coupled Device); s2, calibrating the relation between the camera and the point spectrum; S3, calibrating an axis C; S4, calibrating an axis B; and S5, establishing a coordinate system. According to the invention, the establishment of a new space coordinate system is realized, the precision of the five-axis movement mechanism is optimized, the calibration through the combination of a camera and laser is realized, and the high efficiency and accuracy of the system are ensured.

Description

Technical Field

[0001] The invention relates to an error compensation technology in a five-axis motion mechanism, and in particular to the field of a mathematical modeling method based on a double turntable. Background Art

[0002] Five-axis motion mechanisms are widely used in high-precision machining fields, such as mold manufacturing, aerospace parts, and precision medical equipment. The prior art mainly relies on traditional coordinate system modeling and error compensation methods. For example, the public document with announcement number CN104460513A, publication date March 25, 2015, and patent name "Volume Error Compensation Device for Double-Turntable Five-Axis Machine Tool", discloses a volume error compensation device for a double-turntable five-axis machine tool. The software-based error compensator is mainly composed of a data acquisition module, a DSP module, and an interface module. The data acquisition module is mainly used to preprocess and A / D convert temperature signals and current signals. The DSP module has built-in volume error models and compensation motion models. The temperature signals and current signals converted by A / D and the processing position signals fed back by the parallel port are simultaneously input into the built-in volume error model of the DSP module to predict the volume error of the double-turntable five-axis machine tool in real time. The volume error prediction value is decoupled through the built-in compensation motion model of the DSP to obtain the compensation motion parameters of each axis. The interface module is mainly composed of 1 serial port and 2 parallel ports. The serial port is connected to a personal computer, the model is placed in the DSP, and the compensation process is monitored in real time. Parallel port 1 is mainly used to feed back the processing position signal of the machine tool, and parallel port 2 is mainly used to send the decoupled compensation parameters of each axis to the CNC interface card.

[0003] There are also methods that assume that the relationship between the axes is orthogonal and use linear models for error compensation. These devices compare the preset geometric model with the actual measurement data, calculate the error and compensate. However, these traditional methods fail to fully consider the nonlinear characteristics and complex motion relationships that may occur in the actual processing of the equipment.

[0004] Disadvantages of existing technology

[0005] 1. Insufficient precision: In the existing technology, the establishment of conventional coordinate systems relies on fine-tuning by means of interferometers and other detection methods, which cannot ensure that the three axes are perpendicular to each other. This geometric relationship leads to 21 errors, including but not limited to: geometric errors in structural design, motion errors caused by transmission mechanisms, calibration algorithm errors in system calibration, and dynamic errors during movement: errors caused by acceleration, deceleration and external interference during movement;

[0006] 2. Error accumulation: During multiple processing, errors may gradually accumulate and affect the quality of the final product;

[0007] 3. Poor flexibility: Existing compensation methods usually rely on fixed geometric models and are not suitable for five-axis devices of different types and configurations, which limits their scope of application;

[0008] 4. Response time delay: The real-time compensation capability based on linear models is limited and cannot respond to dynamic changes occurring during the processing process in a timely manner. Summary of the invention

[0009] The technical problem to be solved by the present invention is to realize a mathematical modeling method based on a double turntable, which can effectively reduce errors and improve the machining accuracy of a five-axis motion mechanism.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is: a method for optimizing the accuracy of a five-axis motion mechanism, comprising the following steps:

[0011] S1 calibrates the camera’s pixel ratio and CCD rotation angle;

[0012] The relationship between S2 calibration camera and point spectrum:

[0013] S3 Calibration C-axis:

[0014] S4 Calibration B-axis:

[0015] S5 establishes a coordinate system.

[0016] In S1, the pixel ratio is measured by using the radius of the circle on the calibration plate, the calibration plate is kept stationary, the motion axis moves along the X direction, and the change of the center position of the circle is recorded to measure the rotation angle of the CCD;

[0017] In S2, the intersection of the pyramid is determined in the camera, three planes are synthesized using laser, the intersection of the planes is determined, and the relationship between the camera and the laser is calculated;

[0018] In S3, the laser measures four points on the ring, uses these points to fit the plane Ax+By+Cz+D=0, converts the camera coordinates to the laser coordinate system, and calculates the height value Z of the center of the circle by the plane equation;

[0019] In S4, four straight lines are drawn on the plane using a laser, and three intersection points are obtained to determine the center O1 of the circle. The laser is moved a certain distance along the Y axis, and step 1 is repeated to obtain the center O2 of the circle. The line connecting the centers O1 and O2 determines the normal vector of the B axis, and O1 is taken as a point on the axis.

[0020] In S5, a coordinate system is established with the B and C axes, the common perpendicular line O'M of BC is defined as the X' axis, the B axis is the Y' axis, and the Z' axis is obtained by the cross product of X' and Y', and finally Z'=X'×Y' is obtained.

[0021] The S2 comprises the following steps:

[0022] Step 1: Use the camera to measure the intersection of line BA and surface BC, and the intersection point is P_cam;

[0023] Step 2: Use point spectrum to measure 4 points on planes B, A, and C, and fit them into planes respectively. The intersection of the planes is P_laser;

[0024] Step 3: Calculate the relationship between the camera and the laser: Cam_to_Laser = P_cam-P_laser, the height reading of the laser quantitative center is H.

[0025] In S3, the circular calibration plate is placed on a turntable, the C axis rotates, and a position is measured every 60 degrees. The camera records the coordinates C (x, y) of the center of each circle. At each position, the laser measures four points on the circular ring, and these points are used to fit the plane Ax + By + Cz + D = 0. The camera coordinates are converted to the point spectrum coordinate system, and the height value Z of the center of the circle is calculated by the plane equation. Finally, the center coordinates P_i (X, Y, Z) of each position are obtained, and these points are used to fit the normal vector of the C axis and a point on the C axis.

[0026] The S4 comprises the following steps:

[0027] Step 1: With the A and B axes at four different angles (rotated around the Y axis), use the point spectrum to draw four straight lines on the plane and find three intersection points to determine the center of the circle O1;

[0028] Step 2: Move the laser a certain distance along the Y axis, repeat step 1, and find the center O2;

[0029] Step 3: The line connecting the centers O1 and O2 determines the normal vector of the B axis, with O1 as a point on the axis.

[0030] The step S6 is also included, coordinate system conversion: the conversion relationship from the workpiece coordinate system to the mechanical coordinate system is:

[0031]

[0032] Machine coordinate system to workpiece coordinate system: N = M -1

[0033] Project the C axis and point M to the workpiece coordinate system to obtain C' and M'. Let the normal vector of the point around point M' in the workpiece coordinate system be C' and the rotation matrix be: Rot(C)

[0034] The matrix around the B axis is

[0035]

[0036] The transformation relationship from the mechanical coordinate system to the workpiece coordinate system is:

[0037] M(mcs_to_pcs)=Rot(C)*Rot(B)*N.

[0038] A five-axis motion mechanism precision optimization system comprises:

[0039] Five-axis control system, human-computer interaction module, sensor module and data processing module

[0040] The five-axis control system connects each power axis of the system and outputs drive instructions to each power axis;

[0041] The human-computer interaction module is connected to an interaction port of the data processing module;

[0042] The sensor module is used to obtain the calibrated raw data and the accuracy of the detection platform, monitor the motion state in real time, and output data signals to the data processing module;

[0043] The data processing module performs algorithm processing, optimizes motion control through data analysis, and connects and outputs control instructions to the five-axis control system.

[0044] The sensor module includes: a visual system, a point spectrum, and an interferometer.

[0045] A storage medium is a computer-readable storage medium for storing software program codes, and the software program codes are used to execute the five-axis motion mechanism accuracy optimization method.

[0046] The present invention realizes the establishment of a new spatial coordinate system, optimizes the accuracy of the five-axis motion mechanism, realizes how to perform calibration through the combination of camera and laser, and ensures the efficiency and accuracy of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The following is a brief description of the contents expressed in each figure in the specification of the present invention and the marks in the figure:

[0048] Figure 1 A framework diagram for the dual-turntable five-axis system design of the present invention;

[0049] Figure 2 This is a schematic diagram of the structure of the double-turntable five-axis system of the present invention;

[0050] Figure 3 The double turntable space modeling workflow diagram of the present invention;

[0051] Figure 4 Calibrate the camera and mechanical coordinate system trajectory diagram for the present invention;

[0052] Figure 5 Schematic diagram of camera calibration and point spectrum of the present invention;

[0053] Figure 6This is a schematic diagram of the C-axis calibration of the present invention;

[0054] Figure 7 This is a schematic diagram of the B-axis calibration of the present invention;

[0055] Figure 8 This is a schematic diagram of modeling the dual turntable space coordinate system of the present invention;

[0056] The markings in the above figures are: 1, X-axis; 2, Y-axis; 3, Z-axis; 4, B-axis; 5, C-axis; 6, stage; 7, point spectrum; 8, camera. DETAILED DESCRIPTION

[0057] The following is a further detailed description of the specific implementation methods of the present invention, such as the shape, structure, relative position and connection relationship between the various components involved, the function and working principle of each part, the manufacturing process and operation method, etc., through the description of the embodiments with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0058] The defects of the error analysis and compensation methods of the linear kinematic model of the five-axis motion equipment currently used are due to the reliance of traditional technology on simple linear models, which fails to take into account the complex kinematic characteristics and nonlinear factors in actual operation. In addition, the lack of sufficient real-time data feedback mechanism makes the existing error compensation methods insufficient in dynamic adjustment. Therefore, in view of these shortcomings, the present invention proposes a mathematical modeling method based on a dual turntable to more effectively reduce errors and improve the machining accuracy of the five-axis motion mechanism.

[0059] The five-axis motion mechanism precision optimization system includes a five-axis control system, a human-computer interaction module, a sensor module, and a data processing module. The five-axis platform includes the control systems of the X-axis 1, the Y-axis 2, the Z-axis 3, the B-axis 4, and the C-axis 5, which are used to realize the control of multi-directional motion to ensure processing accuracy and flexibility.

[0060] The five-axis control system will control the inching and continuous movement of the axis to ensure the flexibility and accuracy of the movement;

[0061] The sensor module obtains the calibrated raw data and the accuracy of the detection platform, and monitors the motion status in real time;

[0062] The data processing module performs algorithm processing and optimizes motion control through data analysis;

[0063] The human-computer interaction module displays the current status, making it easy for operators to monitor and adjust in real time.

[0064] The sensor module contains:

[0065] The visual system, which consists of an area array camera 8 , a light source and a light source sensor, is used to obtain high-quality images of a calibration plate or a workpiece and is installed on the Z axis 3 .

[0066] The point spectrum 7 is used to measure the height of the workpiece and calibrate the camera 8 and the point spectrum 7. It is installed at the bottom of the Z axis 3 and is only used for calibration. It can be removed after calibration to save costs.

[0067] Interferometer, which is used to accurately measure the motion accuracy of the five-axis platform, ensuring high precision in each motion cycle.

[0068] The design of the sensor module covers a variety of sensors such as vision, point spectrum 7 and interferometer, which improves the system's monitoring capabilities and data accuracy.

[0069] The human-computer interaction module includes a display and an industrial computer, which is used to provide a user-friendly interface for operators to set parameters, monitor processing status and perform data analysis.

[0070] The data processing module includes:

[0071] Software module, which is used for data collection, classification and storage to ensure data reliability.

[0072] Algorithm module:

[0073] The calibration algorithm is used to calibrate the pixel ratio and CCD rotation angle of the camera 8, the relationship between the camera 8 and the point spectrum 7, and the motion accuracy of the B axis 4 and the C axis 5.

[0074] Image processing algorithms are used for filtering, segmentation and positioning of images, and for extracting feature points to improve the accuracy of subsequent processing.

[0075] Distortion correction algorithm is used to improve the accuracy of the image and provide more accurate basic data for subsequent calibration.

[0076] A modeling algorithm is used to establish a new coordinate system, in which the B axis 4 is determined as a main axis in the coordinate system as the Y axis 2 (y'), and the C axis 5 and the B axis 4 are two non-coplanar straight lines that cannot intersect in the same plane. A perpendicular foot is established on the B axis 4 as the origin O' of the coordinate system, and the X axis 1 (x') is defined by the common perpendicular line of the BC axis 5 so that it is perpendicular to the B axis 4, and the Z axis 3 (z') is determined by the cross multiplication rule of X' and Y'.

[0077] The system uses advanced algorithm modules, including calibration, image processing and modeling algorithms, to ensure the efficiency and accuracy of data processing. The modular structure of the system provides good scalability and adaptability, facilitating future technology updates and functional expansion.

[0078] The algorithm flow of the five-axis motion mechanism precision optimization system includes the following steps:

[0079] S1 Calibrate the pixel ratio and CCD rotation angle of camera 8: Measure the pixel ratio by using the radius of the circle on the calibration plate. Figure 4 As shown, the calibration plate is kept stationary, the motion axis moves along the X direction, and the camera 8 records the change of the center position to measure the rotation angle of the CCD.

[0080] S2 calibrates the relationship between the camera 8 and the point spectrum 7: determine the intersection of the pyramid in the camera 8, synthesize three planes with laser, determine the intersection of the planes, and calculate the relationship between the camera 8 and the laser;

[0081] like Figure 5 Shown

[0082] Step 1: In camera 8, measure the intersection of line BA and surface BC, and the intersection point is P_Cam.

[0083] Step 2: Use point spectrum 7 to measure 4 points on planes B, A, and C, and fit them into planes respectively. The intersection of the planes is P_laser.

[0084] Step 3: Calculate the relationship between the camera 8 and the laser: Cam_to_Laser=P_cam-P_laser, the height reading of the laser quantitative center is H.

[0085] S3 calibrates the C axis 5: The laser measures four points on the circle, and uses these points to fit the plane Ax+By+Cz+D=0, converts the camera 8 coordinates to the laser coordinate system, and calculates the height value Z of the center of the circle through the plane equation.

[0086] like Figure 6 As shown, the circular calibration plate is placed on a turntable, the C-axis 5 rotates, and a position is measured every 60 degrees. The camera 8 records the coordinates C(x, y) of each center of the circle. At each position, the laser measures four points on the circular ring, and these points are used to fit the plane Ax+By+Cz+D=0. The camera 8 coordinates are converted to the point spectrum 7 coordinate system, and the height value Z of the center of the circle is calculated by the plane equation. Finally, the center coordinates P_i(X, Y, Z) of each position are obtained, and these points are used to fit the normal vector of the C-axis 5 and a point on the C-axis 5.

[0087] S4 calibrates B axis 4: Use laser to draw four straight lines on the plane, find three intersection points to determine the center O1, move the laser along Y axis 2 for a certain distance, repeat step 1 to find the center O2; the line connecting the centers O1 and O2 determines the normal vector of B axis 4, and O1 is taken as a point on the axis.

[0088] like Figure 7 As shown,

[0089] Step 1: A and B axes 4 are at four different angles (rotated around Y axis 2), and four straight lines are drawn on the plane using point spectrum 7, and three intersection points are obtained to determine the center O1 of the circle.

[0090] Step 2: Move the laser a certain distance along the Y axis 2, repeat step 1, and find the center O2.

[0091] Step 3: The line connecting the centers O1 and O2 determines the normal vector of the B axis 4, with O1 as a point on the axis.

[0092] S5 establishes a coordinate system: Figure 8 As shown, the position of the B axis 4 and the C axis 5 is measured using the point spectrum 7. A coordinate system is established with the B axis 4 and the C axis 5. The B axis 4 and the C axis 5 do not need to be perpendicular or intersecting each other. The common perpendicular line O'M of the B axis 4 and the C axis 5 is defined as the X' axis, the B axis 4 is the Y' axis, and the Z' axis is obtained by the cross product of X' and Y', that is, Z'=X'×Y'.

[0093] The mathematical modeling method of the dual turntable is used to achieve precise control and optimization of the five-axis motion mechanism, providing a theoretical basis for dynamic error compensation. The system can obtain the motion state in real time, respond and adjust quickly, and ensure high precision and stability of the motion.

[0094] S6 coordinate system conversion: The conversion relationship from the workpiece coordinate system to the machine coordinate system is:

[0095] Machine coordinate system to workpiece coordinate system: N = M -1

[0096] Project the C axis 5 and point M to the workpiece coordinate system to obtain C' and M'. Let the normal vector of the point around point M' in the workpiece coordinate system be C' and the rotation matrix be: Rot(C)

[0097] The matrix around axis B is

[0098]

[0099] The transformation relationship from the mechanical coordinate system to the workpiece coordinate system is:

[0100] M(mcs_to_pcs)=Rot(C)*Rot(B)*N.

[0101] The above system and method have the following advantages:

[0102] Real-time monitoring and feedback: The sensor module and data processing module integrated in the system can obtain the motion status in real time, quickly feedback and adjust the motion parameters to ensure high precision and stability of each motion cycle.

[0103] Multi-sensor fusion: Through the combination of vision system, point spectrum 7 and interferometer, the system can comprehensively monitor motion accuracy, optimize data collection, and improve measurement accuracy and reliability.

[0104] Algorithm optimization: The use of advanced calibration algorithms, image processing algorithms and modeling algorithms can effectively improve data processing efficiency, optimize motion control logic, and enhance overall system performance.

[0105] Modular design: The modular design of the system makes it highly scalable and flexible, facilitating subsequent functional upgrades and maintenance, and adapting to different processing requirements.

[0106] User-friendly interface: The human-computer interaction module provides an intuitive operation interface, which facilitates users to monitor in real time, set parameters and analyze data, improving the convenience and intuitiveness of operation.

[0107] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for optimizing the accuracy of a five-axis motion mechanism, characterized in that: The following steps are involved: S1 calibrates the camera’s pixel ratio and CCD rotation angle; The relationship between S2 calibration camera and point spectrum: S3 Calibration C-axis: S4 Calibration B-axis: S5 establishes a coordinate system.

2. The five-axis motion mechanism precision optimization method according to claim 1, characterized in that: In S1, the pixel ratio is measured by using the radius of the circle on the calibration plate, the calibration plate is kept stationary, the motion axis moves along the X direction, and the change of the center position of the circle is recorded to measure the rotation angle of the CCD; In S2, the intersection of the pyramid is determined in the camera, three planes are synthesized using laser, the intersection of the planes is determined, and the relationship between the camera and the laser is calculated; In S3, the laser measures four points on the ring, uses these points to fit the plane Ax+By+Cz+D=0, converts the camera coordinates to the laser coordinate system, and calculates the height value Z of the center of the circle by the plane equation; In S4, four straight lines are drawn on the plane using a laser, and three intersection points are obtained to determine the center O1 of the circle. The laser is moved a certain distance along the Y axis, and step 1 is repeated to obtain the center O2 of the circle. The line connecting the centers O1 and O2 determines the normal vector of the B axis, and O1 is taken as a point on the axis. In S5, a coordinate system is established with the B and C axes, the common perpendicular line O'M of BC is defined as the X' axis, the B axis is the Y' axis, and the Z' axis is obtained by the cross product of X' and Y', and finally Z'=X'×Y' is obtained.

3. The method for optimizing the accuracy of a five-axis motion mechanism according to claim 2, characterized in that: The S2 comprises the following steps: Step 1: Use the camera to measure the intersection of line BA and surface BC, and the intersection point is P_cam; Step 2: Use point spectrum to measure 4 points on planes B, A, and C, and fit them into planes respectively. The intersection of the planes is P_laser; Step 3: Calculate the relationship between the camera and the laser: Cam_to_Laser = P_cam-P_laser, the height reading of the laser quantitative center is H.

4. The method for optimizing the accuracy of a five-axis motion mechanism according to claim 2, characterized in that: In S3, the circular calibration plate is placed on a turntable, the C axis rotates, and a position is measured every 60 degrees. The camera records the coordinates C (x, y) of the center of each circle. At each position, the laser measures four points on the circular ring, and these points are used to fit the plane Ax + By + Cz + D = 0. The camera coordinates are converted to the point spectrum coordinate system, and the height value Z of the center of the circle is calculated by the plane equation. Finally, the center coordinates P_i (X, Y, Z) of each position are obtained, and these points are used to fit the normal vector of the C axis and a point on the C axis.

5. The method for optimizing the accuracy of a five-axis motion mechanism according to claim 2, characterized in that: The S4 comprises the following steps: Step 1: With the A and B axes at four different angles (rotated around the Y axis), use the point spectrum to draw four straight lines on the plane and find three intersection points to determine the center of the circle O1; Step 2: Move the laser a certain distance along the Y axis, repeat step 1, and find the center O2; Step 3: The line connecting the centers O1 and O2 determines the normal vector of the B axis, with O1 as a point on the axis.

6. The method for optimizing the accuracy of a five-axis motion mechanism according to claim 1 or 2, characterized in that: The step S6 is also included, coordinate system conversion: the conversion relationship from the workpiece coordinate system to the mechanical coordinate system is: Machine coordinate system to workpiece coordinate system: N = M -1 Project the C axis and point M to the workpiece coordinate system to obtain C' and M'. Let the normal vector of the point around point M' in the workpiece coordinate system be C' and the rotation matrix be: Rot(C). The matrix around the B axis is The transformation relationship from the mechanical coordinate system to the workpiece coordinate system is M(mcs_to_pcs)=Rot(C)*Rot(B)*N.

7. A five-axis motion mechanism precision optimization system, characterized in that: System includes Five-axis control system, human-computer interaction module, sensor module and data processing module The five-axis control system connects each power axis of the system and outputs drive instructions to each power axis; The human-computer interaction module is connected to an interaction port of the data processing module; The sensor module is used to obtain the calibrated raw data and the accuracy of the detection platform, monitor the motion state in real time, and output data signals to the data processing module; The data processing module performs algorithm processing, optimizes motion control through data analysis, and connects and outputs control instructions to the five-axis control system.

8. The five-axis motion mechanism precision optimization system according to claim 7, characterized in that: The sensor module includes: a visual system, a point spectrum, and an interferometer.

9. A storage medium, the storage medium being a computer-readable storage medium for storing software program codes, characterized in that: The software program code is used to execute the five-axis motion mechanism accuracy optimization method as described in any one of claims 1-6.

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