Method and system for testing motion flatness based on line laser and position detector calibration

Abstract

The present invention provides a method and system for testing the motion flatness based on line laser and position detector calibration, which relates to the field of high-precision geometric testing. The motion flatness testing method calibrates the position-sensitive detector based on a reference motion platform before measurement to ensure the measurement accuracy, and can accurately measure the scanning space motion flatness of the target test motion platform. The entire testing system is added to the motion control system of the spatial motion platform as an error measurement component for high-precision spatial motion scanning testing, which can measure the flatness error value in real time and feedback it to the motion control system of the spatial motion platform. During the scanning test process, the Z-axis offset value measured on the position-sensitive detector is monitored and read in real time, and the Z-axis component is driven for fine adjustment and calibration, so that the end of the position-sensitive detector always maintains planar motion in the scanning space, realizing high-precision scanning space planar motion.

Description

Technical Field

[0001] The present invention relates to the field of high-precision geometric testing, and particularly to a method and system for testing the flatness of a moving plane based on line laser and position detector calibration. Background Art

[0002] With the increase in the number of radio devices, the available spectrum resources are becoming fewer and fewer. The operating frequency of antennas has been forced to develop from low-end frequencies to high-end frequencies, and the antenna bandwidth has developed from narrow bands to wide bands. Therefore, the development and utilization of millimeter waves with higher frequencies, and even terahertz waves, have become an urgent task. Terahertz waves refer to electromagnetic waves in the frequency spectrum range of 100 GHz to 10 THz. Compared with microwaves, terahertz waves have the characteristics of short wavelengths and large spatial losses, requiring the test system to have a large scanning range (1.5 m × 1.5 m) and high positioning accuracy.

[0003] According to the general rule that the flatness index of the Z-axis plane of the test scanning platform is better than one-thousandth of a wavelength, the flatness of the Z-axis plane of the test scanning platform applied to terahertz waves should be better than 6 μm. Since this Z-axis flatness is not a physical plane but the flatness calculated from the coordinate points of the movement path at the end of the movement of the test scanning platform, general physical flatness test instruments and methods cannot be used, and the test accuracy of laser trackers cannot meet this accuracy requirement. Therefore, it has become a difficult problem to quickly test the flatness of a large scanning range suitable for the terahertz band, and it is even more difficult to achieve real-time correction of large-range scanning to meet this flat movement accuracy requirement. Summary of the Invention

[0004] In order to solve the above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide a method and system for testing the flatness of a moving plane based on line laser and position detector calibration. This flatness test method uses a line laser source to emit a laser straight line as the reference for the spatial plane. The reference light ray is projected onto a one-dimensional position-sensitive detector (PSD). When the light source and the position-sensitive detector have a relative displacement in the direction perpendicular to the one-dimensional position-sensitive detector, the position-sensitive detector can quickly measure the displacement amount, thereby completing the rapid and accurate test of the flatness of a large scanning range, and even real-time correction.

[0005] Specifically, on the one hand, the present invention provides a method for testing the flatness of a moving plane based on line laser and position detector calibration, which includes the following steps:

[0006] S1. Incline and install the laser light source together with the rotating base on the fixed base, and the laser emission direction is parallel to the scanning plane;

[0007] S2. Fix and connect the position-sensitive detector to the Z-axis assembly of the target test moving platform, and the one-dimensional pointing direction of the position-sensitive detector is the same as the Z-axis direction;

[0008] S3. Drive the second base of the target test motion platform to move in the X-axis and Y-axis directions so that the position sensitive detector reaches point A, which is the closest to the laser source. Drive the Z-axis assembly to move in the Z-axis direction so that the laser is projected onto the measurement area of the position sensitive detector and observe the reading of the position sensitive detector. Control the Z-axis assembly to move in the Z-axis direction so that the laser projection line is projected onto the center 0 point of the measurement area of the position sensitive detector;

[0009] S4. Drive the second base of the target test motion platform to move in the X-axis and Y-axis directions so that the position sensitive detector reaches point B, which is at the far end from the laser source. Observe the reading of the position sensitive detector and adjust the yaw angle of the rotating base so that the laser projection line coincides with the center 0 point of the measurement of the position sensitive detector;

[0010] S5. Repeat steps S3 - S4 until the laser projection line can be within a certain range of the center of the measurement area of the position sensitive detector;

[0011] S6. Drive the second base of the target test motion platform to move in the X-axis and Y-axis directions so that the position sensitive detector reaches point C, which is at the far end from the laser source. Observe the reading of the position sensitive detector and adjust the roll angle of the rotating base so that the laser projection line coincides with the center 0 point of the measurement of the position sensitive detector;

[0012] S7. Repeat steps S3 - S6 until the laser projection line can be within a certain range of the center of the measurement area of the position sensitive detector;

[0013] S8. Conduct a scanning test. Keep the Z-axis assembly stationary, drive the target test motion platform to move along a certain path on the XY plane and stop at all predetermined nodes. Use the position sensitive detector to read the Z-axis offset at each node and record the three-dimensional coordinates of all nodes;

[0014] S9. According to the standard method of flatness measurement, calculate the flatness of the scanning space motion plane of the target test motion platform based on the three-dimensional coordinate values of all nodes.

[0015] Preferably, the range in step S5 and step S7 is determined according to the flatness measurement accuracy requirements. Generally, this range is required to be less than or equal to 1 / 3 - 1 / 5 of the flatness measurement accuracy requirements.

[0016] Preferably, step S2 also includes a calibration process for the position sensitive detector, which specifically includes the following sub-steps:

[0017] S21. Install a line laser light source and a position sensitive detector on the reference motion platform;

[0018] S22. Calculate the maximum target distance between the position sensitive detector and the laser source from the planar motion range of the target test motion platform, and determine the distance correction test points of the position sensitive detector: L i For i = 1, 2, 3…n, determine the test accuracy calibration range Z of the position sensitive detector according to the requirements of the flatness of the motion plane of the target test motion platform j For j = 1, 2, 3…m;

[0019] S23. Drive the reference motion platform to move on the straight line where the test point is located, so that the distance between the laser source and the position sensitive detector meets the requirements of the laser source distance from the test point in step S22;

[0020] S24. Drive the reference motion platform to move perpendicular to the linear laser scanning plane along the Z-axis, so that the position reading of the position sensitive detector is 0;

[0021] S25. Drive the reference motion platform to move along the Z-axis to D ij , successively reach the test points determined in step S2, and adjust the N ij value so that the Z-axis offset reading on the position sensitive detector is equal to the actual target offset D ij , read the differential voltage value U- ij and the sum voltage value U+ ij , according to the formula D ij = U- ij U+ ij * N ij , solve for the compensation coefficient N ij , and input the solved compensation coefficient N ij into the position sensitive detector test program, where D ij is the target offset along the Z-axis;

[0022] S26. Repeat steps S23 to S25 to complete the test accuracy correction of the position sensitive detector at all laser source distance test points.

[0023] Preferably, the reference motion platform is a motion platform with completed motion accuracy calibration.

[0024] Preferably, the flatness of the scanning space motion plane in step S9 is calculated based on the flatness error detection.

[0025] On the other hand, the present invention provides a test system for a motion flatness test method based on linear laser and position detector correction, which includes a linear laser light source, a one-dimensional position sensitive detector, a rotating base, and a target test motion platform;

[0026] The line laser light source is inclined and arranged on the fixed base of the target test motion platform by means of a rotating base, and the laser plane projected by the line laser light source can cover all points on the scanning space motion plane. The one-dimensional position sensitive detector is fixed on the Z-axis assembly of the target test motion platform and can move in the X-axis direction, Y-axis direction and Z-axis direction following the target test motion platform.

[0027] Preferably, the target test motion platform includes a fixed base, an X-axis assembly, a Y-axis assembly and a Z-axis assembly; the X-axis assembly includes a first base, an X-direction sliding seat and an X-axis driving motor, the Y-axis assembly includes a second base, a Y-direction sliding seat and a Y-axis driving motor, the Z-axis assembly includes a third base, a Z-direction sliding seat and a Z-axis driving motor. The upper surface of the first base is provided with an X-direction sliding rail, the side surface of the second base is provided with a Y-direction sliding rail, and the inside of the third base is provided with a Z-direction sliding rail. The first base is fixedly connected to the fixed base, the bottom of the second base is fixedly connected to the X-direction sliding seat, and the third base is fixedly connected to the Y-direction sliding seat; the X-axis driving motor can drive the X-direction sliding seat to move along the X-direction sliding rail so as to drive the second base to move in the X-axis direction along the X-direction sliding rail, the Y-axis driving motor can drive the Y-direction sliding seat to move along the Y-direction sliding rail so as to drive the third base to move in the Y-axis direction along the Y-direction sliding rail, and the Z-axis driving motor can drive the Z-direction sliding seat to move along the Z-direction sliding rail so as to drive the one-dimensional position sensitive detector to move in the Z-axis direction along the Z-direction sliding rail.

[0028] Preferably, the line laser light source is inclined and arranged on the fixed base by means of a rotating base. The rotating base includes a rolling motion assembly, a rolling adjustment knob, a yaw adjustment knob, a yaw rotating disc and a light source support seat. The line laser light source is arranged in the groove of the light source support seat and can emit a laser scanning plane. The light source support seat is arranged on the yaw rotating disc, the yaw rotating disc is arranged on the rolling motion assembly, the yaw adjustment knob controls the yaw rotating disc to rotate in the yaw axis direction through a worm and gear transmission structure, and the rolling adjustment knob controls the rolling assembly to rotate in the rolling axis direction through a worm and gear transmission structure.

[0029] Preferably, using this test system as an error measurement component and adding it to the motion control system of the spatial motion platform for high-precision spatial motion scanning test, the flatness error value can be measured in real time and fed back to the motion control system of the spatial motion platform. During the scanning test process, the Z-axis offset value measured on the position sensitive detector is monitored and read in real time, and the Z-axis assembly is driven to perform fine adjustment and correction so that the end of the position sensitive detector always remains in the XY plane motion, realizing high-precision spatial XY plane motion.

[0030] Preferably, using the said test system can realize the continuous motion of the motion platform during planar motion, and it includes the following steps:

[0031] Step 1: Obtain the predicted error value based on the Z - direction error value measured at the previous node of this test.

[0032] Step 2: Compensate the Z - axis position of the current node in advance according to the predicted error value.

[0033] Preferably, the test system can be used to realize the continuous movement of the motion platform during planar motion, which includes the following steps:

[0034] Step 1: Before conducting the uninterrupted planar motion test, first measure and record the Z - direction flatness deviation values at the matrix coordinate points of m×n within the XY - plane motion range.

[0035] Step 2: During the antenna scanning test, by judging the coordinates of the Z - axis component in the XY - plane at any moment, calculate the position deviation at this moment by the difference method and compensate the Z - axis position of the current node in advance.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] (1) The present invention proposes a method for testing the motion flatness based on line - laser and position - detector correction. It uses a line - laser source to emit a laser straight line as the reference for the spatial plane. The reference light ray is projected onto a one - dimensional position - sensitive detector (PSD). When the light source and the position - sensitive detector have a relative displacement in the direction perpendicular to the one - dimensional position - sensitive detector, the position - sensitive detector can quickly measure the displacement amount, thus completing the rapid and accurate test of the flatness of a large scanning range, and even real - time correction.

[0038] (2) Currently, the traditional technology uses the method of measuring by projecting the laser plane formed by the automatic rotation of a point - laser onto a position - sensitive detector. However, this method has extremely high requirements for the accuracy of the laser rotation system to form a stable laser scanning plane, and the technical difficulty is extremely high. The method proposed by the present invention directly replaces the point - laser scanning system with a line - laser source. Under the condition that the accuracy of the laser plane drops little, it reduces the number of components of the test system, greatly improving the reliability and economy of the test system.

[0039] (3) In specific applications, adding the test system of the present application as an error - measurement component to the motion control system of the spatial motion platform for high - precision spatial motion scanning test can measure the flatness error value in real time and feedback it to the motion control system of the spatial motion platform. During the scanning test process, through real - time correction, the end of the position - sensitive detector is always kept moving in the XY - plane, realizing high - precision spatial XY - plane motion. Description of the Drawings

[0040] Figure 1 It is a schematic diagram of the high - precision test structure of the spatial motion of the present invention;

[0041] Figure 2 Schematic diagram of the high-precision spatial motion testing method of the present invention;

[0042] Figure 3 Schematic diagram of the line laser light source base and rotation axis adjustment of the present invention;

[0043] Figure 4 Schematic diagram of the plane scanning path of the present invention;

[0044] Figure 5 Schematic diagram of the calibration method of the present invention;

[0045] Figure 6 Schematic diagram of the principle of P-point error prediction based on the Z-direction error sequence measured from the previous nodes of the present invention;

[0046] Figure 7 Schematic diagram of the principle of P-point error estimation based on the difference of the pre-measured m×n flatness error matrix E of the present invention. Detailed implementation manners

[0047] Hereinafter, the implementation manners of the present invention will be described with reference to the accompanying drawings.

[0048] On the one hand, the present invention provides a flatness testing method for spatial motion based on line laser and position detector correction, which includes the following steps:

[0049] S1. Incline and install the laser light source together with the rotating base on the fixed base, and the laser emission direction is parallel to the scanning plane.

[0050] S2. Fix and connect the position sensitive detector to the Z-axis assembly of the target test motion platform, and the one-dimensional pointing direction of the position sensitive detector is the same as the Z-axis.

[0051] Preferably, step S2 further includes the position sensitive detector correction process, as Figure 5 shown, and specifically includes the following sub-steps:

[0052] S21. Install the line laser light source and the position sensitive detector on the reference motion platform.

[0053] S22. Calculate the farthest target distance between the position sensitive detector and the laser source from the plane motion range of the target test motion platform, and determine the distance correction test points of the position sensitive detector: L i i = 1, 2, 3…n, and determine the position sensitive detector test accuracy calibration range Z j j = 1, 2, 3…m according to the requirements of the plane flatness of the target test motion platform.

[0054] S23. Drive the reference motion platform to move along the straight line where the test point is located, so that the distance between the laser source and the position sensitive detector meets the requirement of the distance between the laser source and the test point in step S22.

[0055] S24. Drive the reference motion platform to move perpendicular to the line laser scanning plane along the Z-axis, so that the position reading of the position sensitive detector is 0.

[0056] S25. Drive the reference motion platform to move along the Z-axis to D ij , and successively reach the test points determined in step S2, and adjust the N ij value so that the Z-axis offset reading on the position sensitive detector is equal to the actual target offset D ij , read the differential voltage value U- ij and the sum voltage value U+ ij , according to the formula D ij = U- ij U+ ij * N ij , solve the compensation coefficient N ij , and input the solved compensation coefficient N ij into the position sensitive detector test program, where D ij is the Z-axis target offset.

[0057] S26. Repeat steps S23 - S25 to complete the test accuracy correction of the position sensitive detector at all positions where the laser source is at the test points.

[0058] S3. Drive the second base of the target test motion platform to move in the X-axis direction and the Y-axis direction, so that the position sensitive detector reaches point A closest to the laser source. Drive the Z-axis assembly to move in the Z-axis direction, so that the laser projects onto the measurement area of the position sensitive detector and observe the reading of the position sensitive detector. Control the Z-axis assembly to move in the Z-axis direction so that the laser projection line projects onto the center 0 point of the measurement area of the position sensitive detector.

[0059] S4. Drive the second base of the motion platform to move in the X-axis direction and the Y-axis direction, so that the position sensitive detector reaches point B at the far end from the laser source. Observe the reading of the position sensitive detector, and adjust the yaw angle of the rotating base so that the laser projection line coincides with the center 0 point of the measurement center of the position sensitive detector.

[0060] S5. Repeat steps S3 - S4 until the laser projection line can be within a certain range of the center of the measurement area of the position sensitive detector.

[0061] S6. Drive the second base of the target test motion platform to move in the X-axis and Y-axis directions, so that the position sensitive detector reaches point C at the far end of the distance from the laser source, observe the reading of the position sensitive detector, and adjust the roll angle of the rotating base to make the laser projection line coincide with the measurement center 0 of the position sensitive detector.

[0062] S7. Repeat steps S3 - S6 until the laser projection line can be located within a certain range at the center of the measurement area of the position sensitive detector.

[0063] The ranges in step S5 and step S7 are determined according to the flatness measurement accuracy requirements. Generally, this range is required to be less than or equal to 1 / 3 - 1 / 5 of the flatness measurement accuracy requirements.

[0064] S8. Scan the flatness of the spatial motion. Keep the Z-axis component stationary, drive the target test motion platform to move along a certain path on the XY plane, and stop at all predetermined nodes. Use the position sensitive detector to read the Z-axis offset at each node and record the three-dimensional coordinates of all nodes.

[0065] S9. According to the standard method of flatness measurement, calculate the flatness of the scanning space motion and the XY flatness of the target test motion platform based on the three-dimensional coordinate values of all nodes. The XY flatness of the spatial motion of the position sensitive detector in step S9 is calculated according to the flatness error detection.

[0066] On the other hand, the present invention provides a test system for a motion flatness test method based on line laser and position detector calibration, as Figure 1 and Figure 2 shown, which includes a line laser light source 2, a one-dimensional position sensitive detector 5, and a target test motion platform. Figure 1 In it, 100 is the motion coordinate system of the target test motion platform, and 200 is the fixed coordinate system where the line laser light source 2 is located. The line laser light source 2 is inclined and arranged on the fixed base 1, and the one-dimensional position sensitive detector 5 is fixed on the Z-axis component of the target test motion platform.

[0067] In this embodiment, the X-axis assembly, Y-axis assembly, and Z-axis assembly all adopt linear slide rails and motor drive for movement. The X-axis assembly 4 includes a first base 41, an X-direction slide 42, and an X-axis drive motor. The Y-axis assembly 6 includes a second base 61, a Y-direction slide 62, and a Y-axis drive motor. The Z-axis assembly 7 includes a third base 71, a Z-direction slide 72, and a Z-axis drive motor. An X-direction slide rail 43 is provided on the upper surface of the first base 41, a Y-direction slide rail 63 is provided on the side surface of the second base 61, and a Z-direction slide rail is provided inside the third base 71. The first base 41 is fixedly connected to the base, the bottom of the second base 61 is fixedly connected to the X-direction slide 42, and the third base 71 is fixedly connected to the Y-direction slide 62. The X-axis drive motor can drive the X-direction slide 42 to move along the X-direction slide rail 43, thereby driving the second base 32 to move in the X-axis direction along the X-direction slide rail 43. The Y-axis drive motor can drive the Y-direction slide 62 to move along the Y-direction slide rail 63, thereby driving the third base 71 to move in the Y-axis direction along the Y-direction slide rail 63. The one-dimensional position sensitive detector is fixed on the Z-direction slide 72, and the Z-axis drive motor can drive the Z-direction slide 72 to move along the Z-direction slide rail, thereby driving the one-dimensional position sensitive detector 5 to move in the Z-axis direction along the Z-direction slide rail.

[0068] The one-dimensional position sensitive detector 5 is fixed on the Z-axis assembly and can move in the X-axis direction, Y-axis direction, and Z-axis direction following the target test moving platform. When the Z-axis assembly itself is stationary relative to the Y-axis assembly, the spatial plane formed by the moving XY assembly is parallel to the XY plane 9 of the laser plane emitted by the laser light source. In this embodiment, the X-direction slide rail, Y-direction slide rail, and Z-direction slide rail are all air-floating guide rails. The X-axis drive motor, Y-axis drive motor, and Z-axis drive motor are all servo motors. In other embodiments, other drive methods can also be adopted.

[0069] As Figure 3 shown, the line laser light source is inclined and arranged on the fixed base by means of a rotating base. The rotating base includes a rolling motion assembly 81, a rolling adjustment knob 82, a yaw adjustment knob 83, a rotating disk 84, and a light source support seat 85. The line laser light source 2 is arranged in the groove of the light source support seat 85 and can emit a laser scanning plane 21. The light source support seat 85 is arranged on the yaw rotating disk 84, and the yaw rotating disk 84 is arranged on the rolling motion assembly 81. The yaw adjustment knob 83 controls the rotation of the yaw rotating disk 84 in the yaw axis direction through a worm and gear transmission structure, and the rolling adjustment knob 82 controls the rotation of the rolling assembly in the rolling axis direction through a worm and gear transmission structure.

[0070] In specific applications, the test system can be applied to high-precision measurement components. Specifically, by using the test system as an error measurement component and adding it to the motion control system of the spatial motion platform for high-precision spatial motion scanning tests, the flatness error value can be measured in real time and fed back to the motion control system of the spatial motion platform. During the scanning test, the Z-axis offset value measured on the position-sensitive detector is monitored and read in real time, and the Z-axis component is driven for fine adjustment and correction, so that the end of the position-sensitive detector always remains in the XY plane for motion, realizing high-precision spatial XY plane motion.

[0071] In some application cases, some special motion requirements demand that the motion platform must move continuously during planar motion without stopping in the middle. During its motion, such as when reaching the XY target point on the plane instantaneously, if the offset of the component from the XY plane is measured by the position-sensitive detector and fed back to the control system, the Z-axis position of the current XY node cannot be corrected in time. Therefore, some methods need to be adopted to correct the Z-axis offset of the current point in advance. In practical applications, the above problems can be solved by using the method of the present invention. Specifically, the test system of the present invention can be used to realize the continuous motion of the motion platform during planar motion, which includes the following steps:

[0072] Step 1: Obtain a predicted error value based on the Z-direction error value measured at the previous node of this test.

[0073] Step 2: Compensate the Z-axis position of the current node in advance according to the predicted error value.

[0074] Among them, the prediction method in Step 1 can adopt means such as time series prediction method based on spline function, multivariate time series model, machine learning, polynomial fitting prediction, etc. to make predictions and obtain prediction values. Compensating the Z-axis position of the current node in advance based on the prediction value can ensure the continuous motion of the motion platform. The principle schematic diagram of the P-point error prediction based on the Z-direction error sequence measured at the previous node is as Figure 6 shown.

[0075] In another embodiment, the test system of the present invention can be used to realize the continuous motion of the motion platform during planar motion, which includes the following steps:

[0076] Step 1: Before officially conducting the uninterrupted planar motion test, first test the Z-direction flatness deviation values at the matrix coordinate points of m×n within the XY plane motion range and record them;

[0077] Step 2: When officially conducting the antenna scanning test, by judging the coordinates of the XY plane where the Z-axis component is located at any moment, calculate the position deviation at this moment by the difference method and compensate the Z-axis position of the current node in advance. Specific embodiments

[0079] This embodiment takes the flatness test of the moving plane of a high-frequency millimeter-wave antenna test scanning frame as an example, and its flatness requirement is 5 μm. The flatness measurement plane of the scanning frame is the XY plane, and the scanning range is ±1.5 m along the X-axis and ±1.5 m along the Y-axis. The definitions of the XYZ axes are as Figure 2 shown. In this embodiment, the line laser is fixedly connected to the marble base of the scanning frame, and the position-sensitive detector is fixedly connected to the Z-axis moving structure of the scanning frame. The laser plane projected by the line laser is perpendicular to the measurement direction of the one-dimensional position-sensitive detector. Before starting the measurement and control, use the method for testing and real-time correction of the spatial moving flatness of the line laser and position-sensitive detector of the present invention, and proceed according to the following steps:

[0080] S1. Install the laser light source together with the base on the marble base surface of the scanning frame, and the laser emission direction is approximately parallel to the scanning plane.

[0081] S2. Fix the position-sensitive detector to the Z-axis of the scanning frame, and its one-dimensional direction is the same as the Z-axis.

[0082] S3. Define the driving of the XY axes of the scanning frame to make the position-sensitive detector reach point A, the closest point to the laser source. Drive the Z-axis of the scanning frame to make the laser project onto the measurement area of the position-sensitive detector, and observe the reading of the position-sensitive detector. Fine-tune the control of the Z-axis movement to make the laser projection line project onto the center 0 point of the measurement area of the position-sensitive detector.

[0083] S4. Drive the XY axes of the scanning frame to make the position-sensitive detector reach point B, the farthest point from the laser source, observe the reading of the position-sensitive detector, and adjust the yaw angle of the laser source base, as Figure 3 shown, to make the laser projection line coincide with the center 0 point of the measurement of the position-sensitive detector.

[0084] S5. Repeat steps S3 - S4 until the laser projection line can be ensured to be within ±1 μm of the center of the measurement area of the position-sensitive detector without adjustment.

[0085] S6. Drive the XY axes of the scanning frame to make the position-sensitive detector reach point C, the farthest point from the laser source, observe the reading of the position-sensitive detector, and adjust the roll angle of the laser source base to make the laser projection line coincide with the center 0 point of the measurement of the position-sensitive detector.

[0086] S7. Repeat steps S3 - S6 until the laser projection line can be ensured to be within ±1 μm of the center of the measurement area of the position-sensitive detector without adjustment.

[0087] S8. Start the test, keep the Z-axis stationary, drive the scanning frame to move along the path as Figure 4 shown in the XY plane, and stop at all predetermined nodes. Use the position-sensitive detector to read the Z-axis displacement at each node, and record the (X, Y, Z) coordinates of all nodes.

[0088] S9. According to the flatness measurement standard GB / T 11337-2004, the least squares method is adopted to calculate the XY flatness of the spatial movement of the scanning frame based on the coordinate values of all predetermined points.

[0089] Real-time correction of the planar movement of the scanning frame: In the specific application embodiment, the scanned part is used for accuracy testing and enters the scanning test. The scanning test is carried out according to the XY planar scanning path defined by the test requirements. During the scanning process, the Z-axis offset value measured on the position-sensitive detector is monitored and read in real time, and the Z-axis component is driven for fine adjustment and correction to keep the end of the scanning frame always moving in the XY plane.

[0090] Accuracy calibration of the position-sensitive detector:

[0091] To ensure the accuracy of the movement flatness test of the high-frequency millimeter-wave antenna test scanning frame in this embodiment, it is necessary to calibrate the accuracy of the position-sensitive detector in advance in step S2. During the calibration process, the reference displacement amount of the reference movement platform is used to calibrate the voltage amount fed back by the position-sensitive detector to the control component, and the compensation coefficient is solved to compensate and correct the measurement value of the position-sensitive detector. The calibration steps are as follows:

[0092] S21. Install the line laser and position-sensitive detector displacement test system of the present invention on a set of reference movement platforms (hereinafter referred to as reference movement platforms) that have been calibrated for movement accuracy. The relative position and relative movement mode between the position-sensitive detector and the line laser are the same as those in the normal test link, such as Figure 1 .

[0093] S22. Calculate the maximum distance between the position-sensitive detector and the laser source from the planar movement range of the target test movement platform, and determine the test points for distance correction of the position-sensitive detector: L i i = 1, 2, 3…n, determine the test accuracy calibration range Z of the position-sensitive detector according to the requirements of the movement flatness of the target test movement platform j j = 1, 2, 3…m; in this embodiment, the maximum distance between the position-sensitive detector and the laser source can be calculated as 2.12 m from the scanning range of the scanning frame. Considering the calibration cost, the laser source distance test points are designed accordingly: L i = 0.6 m, 1.0 m, 2.0 m, 2.5 m. According to the requirement of the scanning flatness of the scanning frame of 5 μm, the test accuracy calibration range of the position-sensitive detector is designed as 16 μm, that is, the calibration test points are designed as: Z j = -8 μm, -6 μm, -4 μm, -2 μm, 2 μm, 4 μm, 6 μm, 8 μm.

[0094] S23. Drive the reference movement platform to move on the straight line where the test points are located, so that the distance between the laser source and the position-sensitive detector meets the requirements of the laser source distance test points in step S2.

[0095] S24. Drive the reference motion platform to move the Z-axis perpendicular to the line laser scanning plane so that the position reading of the position sensitive detector is 0.

[0096] S25. Drive the reference motion platform to move along the Z-axis to D ij , successively reach the test points determined in step S2, and adjust N ij value so that the Z-axis offset reading on the position sensitive detector is equal to the actual target offset D ij , read the differential voltage value U- ij and the sum voltage value U+ ij , according to the formula D ij = U- ij U+ ij * N ij , solve the compensation coefficient N ij , and input the solved compensation coefficient N ij into the position sensitive detector test program, where D ij is the Z-axis target offset.

[0097] S26. Repeat steps S23 - S25 to complete the test accuracy correction of the position sensitive detector at all laser source distance test points.

[0098] This flatness test system is used for the scanning frame plane motion loop, and the specific method is as follows:

[0099] In application, add this test system as an error measurement component to the motion control system of the spatial motion platform for high-precision spatial motion scanning test, measure the flatness error value in real time, and feedback it to the motion control system of the spatial motion platform. During the scanning test process, monitor and read the measured Z-axis offset value on the position sensitive detector in real time, and drive the Z-axis component for fine adjustment and correction so that the end of the position sensitive detector always remains in the XY plane motion to achieve high-precision spatial XY plane motion.

[0100] When the motion platform must move continuously during plane motion, first, before the continuous scanning test, test the Z-direction flatness deviation value at the matrix coordinate points of m×n within the XY plane motion range and record it as the m×n flatness error matrix E(X,Y,Err_Z); then start the continuous scanning test. During the continuous motion process, when moving to a certain preset sampling coordinate point P(x,y), call the program to determine which position point P is located in the matrix E, select three adjacent points in E for interpolation, calculate the estimated error of point P, and complete the compensation of the Z-axis position of point P in advance. Among them, the principle of estimating the error of point P based on the difference of the pre-measured m×n flatness error matrix E is shown as Figure 7 shown.

[0101] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for testing the flatness of a moving plane based on line laser and position detector calibration, characterized in that: It includes the following steps: S1. Incline and install the laser light source together with the rotating base on the fixed base, with the laser emission direction parallel to the scanning plane; S2. Fix and connect the position sensitive detector to the Z-axis assembly of the target test moving platform, with the one-dimensional pointing direction of the position sensitive detector being the same as that of the Z-axis; S3. Drive the second base of the target test moving platform to move in the X-axis direction and the Y-axis direction so that the position sensitive detector reaches point A closest to the laser source. Drive the Z-axis assembly to move in the Z-axis direction so that the laser projects onto the measurement area of the position sensitive detector and observe the reading of the position sensitive detector. Control the Z-axis assembly to move in the Z-axis direction so that the laser projection line projects onto the center 0 point of the measurement area of the position sensitive detector; S4. Drive the second base of the target test moving platform to move in the X-axis direction and the Y-axis direction so that the position sensitive detector reaches point B at the far end from the laser source. Observe the reading of the position sensitive detector and adjust the yaw angle of the rotating base so that the laser projection line coincides with the center 0 point of the measurement of the position sensitive detector; S5. Repeat steps S3 - S4 until the laser projection line can be within a certain range of the center of the measurement area of the position sensitive detector; S6. Drive the second base of the target test moving platform to move in the X-axis direction and the Y-axis direction so that the position sensitive detector reaches point C at the far end from the laser source. Observe the reading of the position sensitive detector and adjust the roll angle of the rotating base so that the laser projection line coincides with the center 0 point of the measurement of the position sensitive detector; S7. Repeat steps S3 - S6 until the laser projection line can be within a certain range of the center of the measurement area of the position sensitive detector; S8. Conduct a scanning test. Keep the Z-axis assembly stationary, drive the target test moving platform to move along a certain path on the XY plane and stop at all predetermined nodes. Use the position sensitive detector to read the Z-axis offset at each node and record the three-dimensional coordinates of all nodes; S9. According to the standard method for flatness measurement, calculate the flatness of the scanning space motion plane of the target test moving platform based on the three-dimensional coordinate values of all nodes.

2. The motion flatness testing method based on line laser and position detector correction according to claim 1, characterized in that: The ranges in steps S5 and S7 are determined according to the flatness measurement accuracy requirements, and this range is required to be less than or equal to 1 / 3 - 1 / 5 of the flatness measurement accuracy requirements.

3. The method for testing the motion flatness based on line laser and position detector correction according to claim 1, wherein: Step S2 also includes a position sensitive detector calibration process, which specifically includes the following sub-steps: S21. Install a line laser light source and a position sensitive detector on the reference moving platform; S22. Calculate the farthest target distance between the position sensitive detector and the laser source based on the planar motion range of the target test motion platform, and determine the distance calibration test point of the position sensitive detector: The calibration range of the position sensitive detector test accuracy is determined by the target test motion platform motion flatness requirements. ; S23. Drive the reference moving platform to move on the straight line where the test point is located so that the distance between the laser source and the position sensitive detector meets the requirement of the distance between the laser source and the test point in step S22; S24. Drive the Z-axis of the reference moving platform to move perpendicular to the line laser scanning plane so that the position reading of the position sensitive detector is 0; S25, drive the reference motion platform to move along the Z axis to , successively reach the test points determined in step S2, and adjust value, so that the Z-axis offset reading on the position sensitive detector is equal to the actual target offset , read the differential voltage value of the position sensitive detector and voltage values , according to the formula , solve for the compensation coefficient , and the compensation coefficient to be solved Enter the position sensitive detector test program, where is the Z-axis target offset; S26. Repeat steps S23 - S25 to complete the calibration of the test accuracy of the position sensitive detector at all positions where the laser source is at the test point.

4. The motion flatness testing method based on line laser and position detector correction according to claim 1, characterized in that: The reference moving platform is a moving platform with the motion accuracy calibrated.

5. A testing system for the motion flatness testing method based on line laser and position detector correction according to claim 3, characterized in that: It includes a line laser light source, a one-dimensional position sensitive detector, a rotating base and a target test motion platform; the line laser light source is inclinedly arranged on the fixed base of the target test motion platform by means of the rotating base, and the laser plane projected by the line laser light source can cover all points on the scanning space motion plane. The one-dimensional position sensitive detector is fixed on the Z-axis component of the target test motion platform and can move in the X-axis direction, Y-axis direction and Z-axis direction following the target test motion platform.

6. The test system according to claim 5, wherein: The target test motion platform includes a fixed base, an X-axis component, a Y-axis component and a Z-axis component; the X-axis component includes a first base, an X-direction slide and an X-axis drive motor. The Y-axis component includes a second base, a Y-direction slide and a Y-axis drive motor. The Z-axis component includes a third base, a Z-direction slide and a Z-axis drive motor. An X-direction slide rail is arranged on the upper surface of the first base, a Y-direction slide rail is arranged on the side surface of the second base, and a Z-direction slide rail is arranged inside the third base. The first base is fixedly connected to the fixed base, the bottom of the second base is fixedly connected to the X-direction slide, and the third base is fixedly connected to the Y-direction slide; the X-axis drive motor can drive the X-direction slide to move along the X-direction slide rail, thereby driving the second base to move in the X-axis direction along the X-direction slide rail. The Y-axis drive motor can drive the Y-direction slide to move along the Y-direction slide rail, thereby driving the third base to move in the Y-axis direction along the Y-direction slide rail. The Z-axis drive motor can drive the Z-direction slide to move along the Z-direction slide rail, thereby driving the one-dimensional position sensitive detector to move in the Z-axis direction along the Z-direction slide rail.

7. The test system according to claim 5, wherein: The line laser light source is inclinedly arranged on the fixed base by means of the rotating base. The rotating base includes a rolling motion component, a rolling adjustment knob, a yaw adjustment knob, a yaw rotating disc and a light source support seat. The line laser light source is arranged in the groove of the light source support seat and can emit a laser scanning plane. The light source support seat is arranged on the yaw rotating disc, and the yaw rotating disc is arranged on the rolling motion component. The yaw adjustment knob controls the rotation of the yaw rotating disc in the yaw axis direction through a worm and gear transmission structure, and the rolling adjustment knob controls the rotation of the rolling component in the rolling axis direction through a worm and gear transmission structure.

8. The test system according to claim 7, wherein: Using this test system as an error measurement component and adding it to the motion control system of the space motion platform for high-precision space motion scanning test, it can measure the flatness error value in real time and feedback it to the motion control system of the space motion platform. During the scanning test process, the Z-axis offset value measured on the position sensitive detector is monitored and read in real time, and the Z-axis component is driven for fine adjustment and correction, so that the end of the position sensitive detector always remains in the scanning space motion plane, realizing high-precision scanning space plane motion.

9. The test system according to claim 7, characterized in that: Using the said test system can realize the continuous motion of the motion platform during planar motion, which includes the following steps: Step 1: Obtain a predicted error value based on the Z-direction error value measured at the previous node of this test. Step 2: Compensate the Z-axis position of the current node in advance according to the predicted error value.

10. The test system according to claim 7, wherein: Using the said test system can realize the continuous motion of the motion platform during planar motion, which includes the following steps: Step 1. Before performing the continuous planar motion test, first test the Z-plane flatness deviation values at the matrix coordinate points of within the XY-plane motion range and record them; ​ Step 2: When performing antenna scanning tests, by judging the coordinates of the Z-axis component in the XY plane at any moment, calculate the position deviation at this moment in a difference manner and compensate the Z-axis position of the current node in advance.

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