Front measurement element evaluation method and equipment based on back reference, and medium

Abstract

The invention relates to the technical field of precision machinery, and provides a front measurement element evaluation method and device based on back reference and a medium, a camera is controlled to establish a back coordinate system according to a reference point and a two-dimensional coordinate, and a first coordinate in the back coordinate system and a second coordinate in the back coordinate system are measured and obtained; controlling the product to be tested to turn over; controlling the camera machine coordinate system to measure and obtain a third coordinate in the machine coordinate system and a fourth coordinate in the machine coordinate system; obtaining affine transformation parameters according to the first coordinate, the second coordinate, the third coordinate and the fourth coordinate; obtaining a mirror image reference point and a two-dimensional coordinate; obtaining a datum point and a two-dimensional coordinate of a front corresponding datum point through affine transformation parameters, and establishing a front evaluation coordinate system; and evaluating the data of the front measurement element under the front evaluation coordinate system.

Description

Technical Field

[0001] This invention relates to the field of precision machinery technology, and specifically to a method, device and medium for evaluating front-side measurement elements based on a back-side reference. Background Technology

[0002] A probe is a tool used for measurement and detection, typically made of metal or plastic, with a sharp tip. Depending on the application, probes can be categorized into three types: medical probes, scientific probes, and industrial probes.

[0003] The probe tip is an indispensable core component. Before application, the tip position needs to be precisely measured to ensure the accuracy of subsequent testing. Image measurement is currently the most widely used measurement method in the field of non-contact precision measurement. It has the advantages of high measurement speed and micron-level accuracy. Ordinary image measurement often establishes a measurement reference on the product under test (DUT) while keeping the product's position unchanged, and then measures the measured part of the product on this reference to establish evaluation data. However, if the reference and the measured part of the DUT are not on the same surface, and the product imaging is limited to the upper surface of the product (meaning the back of the product needs to be rotated 180 degrees to be measured), then ordinary measurement methods cannot establish a reference based on the measured elements on the back of the DUT to evaluate the measured elements on the front due to the change in product position. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method, device, and medium for evaluating front-side measurement elements based on a back-side reference. This method uses the back-side measurement elements of a product as an XY reference to transform the back-side measurement elements of the product under test to the corresponding front-side position. Then, a coordinate system is established with the corresponding front-side position as the reference. The front-side measurement elements are substituted into the coordinate system to obtain the measured coordinate values ​​of the front-side elements, which are then compared with theoretical values ​​for evaluation.

[0005] To address the above problems, the present invention provides the following technical solution: In a first aspect, embodiments of this application provide a method for evaluating front-side measurement elements based on a back-side reference, the method comprising: The camera is controlled based on the machine coordinate system to measure two reference points on the back of the product under test. and Two-dimensional coordinates, based on the reference point and A back face coordinate system is established using two-dimensional coordinates, and two reference points on the back face are measured based on this coordinate system. and ,get The first coordinate in the back coordinate system and The second coordinate in the back coordinate system; Control the product under test to flip up and down; Control the camera to measure the frontal reference point based on the machine coordinate system. and Two-dimensional coordinates, to obtain In the third coordinate of the machine coordinate system and In the fourth coordinate of the machine coordinate system; wherein, the back reference point and After the product under test is flipped over, the corresponding front reference points are as follows: and , The affine transformation parameters are obtained based on the first, second, third, and fourth coordinates. These affine transformation parameters are used to transform the back reference point. and Mapped to the frontal reference point and ; According to the back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates; According to the mirror reference point and The two-dimensional coordinates are used to obtain the corresponding reference point on the front side through the affine transformation parameters. and The two-dimensional coordinates, based on the reference point corresponding to the front face. and A two-dimensional coordinate system is established for positive evaluation, which is used to evaluate positive measurement elements.

[0006] In some embodiments, the product under test is provided with a measurement mark, the measurement mark is provided with a reference point, and the measurement mark can be captured by a camera when the product under test is on the back and / or flipped to the front.

[0007] Furthermore, the measuring marker is two sheet-like bodies with through holes, the through holes being circular, and the centers of the two through holes respectively corresponding to reference points. and .

[0008] In some implementations, the affine transformation parameters are obtained based on the first coordinate, the second coordinate, the third coordinate, and the fourth coordinate, including: The form of the affine transformation moment matrix is ​​determined as follows: ; The transformation formula is determined as follows: =a*x+b*y+ , =c*x+d*y+ ; Where a, b, c, and d are parameters that control scaling, rotation, and shearing. and To control the parameters of translation, The original two-dimensional coordinates, The coordinates are two-dimensional coordinates after affine transformation; The first coordinate in the back coordinate system is represented as ( , ), The second coordinate in the back coordinate system is represented as ( , ), The third coordinate in the machine coordinate system is represented as , The fourth coordinate in the machine coordinate system is represented as ( , ); Calculate the original vector =( , )-( , ), target vector ( , )

[0009] Calculate the original vector Rotate to target vector rotation angle The values ​​of the cosine and sine functions: =( ) / ( ), ( ) / ( ); Calculate the scaling factor: / ; Construct the rotation and scaling matrix: ; in, The parameter a corresponds to the affine transformation moment matrix. Corresponding parameter b, Corresponding parameter c, Corresponding parameter d; Calculate translation components and : =( , ) x-

[0010] =( , ) y- ]; The affine transformation moment matrix is ​​obtained.

[0011] In some embodiments, affine transformation parameters are obtained based on the first coordinate, second coordinate, third coordinate, and fourth coordinate, and these affine transformation parameters are used to transform the back face reference point. and Mapped to the frontal reference point and According to the mirror reference point and The two-dimensional coordinates are used to obtain the corresponding reference point on the front side through the affine transformation matrix. and Two-dimensional coordinates, including: Based on the reference point on the back and Connect the lines to construct a straight line, construct the midpoint on the straight line, and rotate the straight line 90° around the midpoint to obtain a mirror axis of symmetry; Mirror the back reference point according to the axis of symmetry. and Obtain mirror reference point and ; Based on the mirror reference point and positive reference points Construct a mirror reference point using two-dimensional coordinates To the positive reference point The translation vector V, based on the mirror reference point and Constructing a mirror reference point using two-dimensional coordinates and Mirror the reference point and and mirror reference point and The translation is performed along the direction defined by vector V, with the translation distance being the magnitude of vector V, to obtain the translation reference point. and and translation reference point and ; Based on the translation reference point and and positive reference points and Construct a translation reference point using two-dimensional coordinates. To the translation reference point straight line and positive reference points and straight line ; According to the straight line and straight line Construct a straight line to the straight line rotation angle Translation reference point and

[0012] and translation reference point and With a positive reference point Based on the rotation angle Rotate to obtain the reference point corresponding to the front face. and Frontal corresponding reference point as well as .

[0013] In some implementations, based on the back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates, including: Based on the reference point on the back and Construct a straight line by connecting coordinates, and then construct the midpoint on that line. Rotate the line 90° around this midpoint to obtain a mirror axis of symmetry. Then, mirror the back reference point based on this axis of symmetry. and Obtain the mirror reference point and Two-dimensional coordinates.

[0014] In some implementations, based on the back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates, including: obtaining the back reference point and The equation of the line that bisects the perpendicular bisector of the line connecting the two points is: Ax + By + C = 0; like The first coordinate in the back coordinate system is represented as ( , ), The second coordinate in the back coordinate system is represented as ( , (Reference point on the back) and The equation of the line that bisects the perpendicular bisector of the line is A = B=1; C= [ +( )· ]; like The coordinates are ( , ),but The coordinate formula is: ( -2A* ; like The coordinates are ( , ),but The coordinate formula is: ( -2A* ,

[0015] in + B + C) / (A² + B²), = (A + B + C) / (A² + B²).

[0016] In some implementations, based on the front-facing corresponding reference point and Establish a positive evaluation coordinate system, which is used to evaluate positive measurement elements, including: When the product under test is flipped 180° from the back to the front, the camera of the image measuring instrument measures the coordinates of the center point of the needle tip under test based on the front evaluation coordinate system, obtains the measured coordinates of the center point of the needle tip, obtains the theoretical coordinates of the center point of the needle tip under test and the range of the needle tip tolerance deviation value, calculates the deviation based on the measured coordinates and theoretical coordinates of the center point of the needle tip, and determines whether the deviation is within the range of the tolerance deviation value.

[0017] Secondly, embodiments of this application provide an image measuring instrument, including: At least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the front measurement element evaluation method based on the back-side reference.

[0018] Thirdly, embodiments of this application provide a computer-readable storage medium: the computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the front-side measurement element evaluation method based on a back-side reference.

[0019] This application provides a method, device, and medium for evaluating front-side elements based on a back-side reference, by measuring two reference points on the back side. and and two reference points and According to the reference point and as well as and The affine transformation parameters are obtained from the two-dimensional coordinates, and the mirror reference point is obtained based on these affine transformation parameters. and The front corresponding reference point and According to the front corresponding reference point and A front evaluation coordinate system is established, and front measurement elements are evaluated based on the front evaluation coordinate system. This invention can evaluate front measurement elements based on the reference established by the back measurement elements of the product under test. In actual use, the needle tip is a functional surface that cooperates with other parts, while the back of the product is the mounting and fixing surface. Evaluating the needle tip position based on the back can determine whether the needle tip can be accurately inserted into the target position and avoid the situation where it cannot be assembled. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating a front-side measurement element evaluation method based on a back-side reference, provided in this embodiment.

[0021] Figure 2 This embodiment provides a schematic diagram of the back structure of the product under test for evaluating front-side measurement elements based on a back-side reference.

[0022] Figure 3This embodiment provides a detailed flowchart illustrating the steps involved in obtaining the affine transformation matrix using a front-side measurement element evaluation method based on a back-side reference.

[0023] Figure 4 This is a schematic diagram of the structure of a front-side measurement element evaluation device based on a back-side reference, provided in this embodiment.

[0024] Figure 5 This is a structural block diagram of a computer-readable storage medium provided in this embodiment.

[0025] Figure label: 1-Product to be tested; 2-First metal sheet; 3-Second metal sheet; 4-Needle tip; 5-First product positioning pin; 6-Second product positioning pin. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0028] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating a front-side measurement element evaluation method based on a back-side reference provided in this embodiment. Figure 1 As shown, the method for evaluating front-side measurement elements based on a back-side reference includes steps 110 to 160.

[0029] Step 110: Control the camera to measure two reference points on the back of the product under test based on the machine coordinate system. and Two-dimensional coordinates, based on the reference point and A back face coordinate system is established using two-dimensional coordinates, and two reference points on the back face are measured based on this coordinate system. and ,get The first coordinate in the back coordinate system and The second coordinate in the back coordinate system; In some implementations, the product to be tested is a workpiece with a needle tip.

[0030] In some implementations, reference points are established according to the requirements on the inspection drawings. and The selection of the test drawings is provided by the customer who requests the test products. The requirements for the test drawings include the selection of the reference point for the product to be tested and the tolerance deviation range of the needle tip. In this embodiment, the reference point is selected as the two product locating pins of the product to be tested. The center positions of the first product locating pin 5 and the second product locating pin 6 are selected as the reference points, respectively. and .

[0031] In some implementations, the camera of the image measuring instrument measures two reference points on the back of the product under test. and The coordinates are specifically the reference points measured in the machine coordinate system set by the camera. and Regarding X and Y coordinates, the camera's machine coordinate system is the most primitive and fundamental coordinate system, defined by its own imaging system and software.

[0032] In some implementations, based on and To establish a back coordinate system, a reference point located on the left side of the product under test can be used. With the origin as the point, Click A two-dimensional coordinate system for the back side is established using the point as the X-axis.

[0033] refer to Figure 2 The product under test has 7 needle tips 4, which are distributed at intervals on the right side wall of the product under test. A first product positioning pin 5 and a second product positioning pin 6 are set near the needle tips 4. The center positions of the first product positioning pin 5 and the second product positioning pin 6 are respectively reference points. and To facilitate the measurement of reference points by the camera of the image measuring instrument, this embodiment provides measurement marks on the product under test. These measurement marks have reference points and can be captured by the camera when the product under test is on its back and / or flipped to its front. Specifically, the measurement marks are two circular, sheet-like bodies with through holes, the centers of which correspond to the reference points. and .

[0034] The sheet-like body is specifically a metal sheet, which is rectangular in shape, but can be a rectangle or a square. Through holes are set to accurately obtain the coordinates of reference points. The uniform area formed by the through holes, which has a strong contrast with the product surface, creates an extremely clear and stable edge contrast, which is convenient for the camera of the image measuring instrument to perform grayscale processing.

[0035] Continue to refer to Figure 2 Specifically, there are two metal plates with circular through holes, both of which are set on the left side wall of the product under test 1. They are the first metal plate 2 and the second metal plate 3, respectively. The centers of the through holes of the first metal plate 2 and the second metal plate 3 are reference points. and .

[0036] In some implementations, when controlling the camera of the image measuring instrument to measure the reference point and reference point, an image of the back of the product to be measured is first acquired, the image is processed in grayscale to obtain hundreds or thousands of discrete pixel coordinate points distributed on the edge of the circular hole, and the center coordinates of the circular through hole are obtained according to the least squares circle fitting algorithm.

[0037] In some embodiments, the through-holes on the metal sheet included in the measuring device can be set as squares, with the center point of the square as a reference point.

[0038] In some implementations, the optical axis of the camera lens is perpendicular to the plane containing the back of the product under test to prevent distortion and increase the accuracy of the measurement reference point.

[0039] In some implementations, the thickness of the metal sheet ranges from 0.5 mm to 1.0 mm, ensuring rigidity without causing significant perpendicularity deviation.

[0040] In this embodiment, a measurement mark is provided on the product under test, and a reference point is provided on the measurement mark. The measurement mark is used by the camera of the image measuring instrument to measure the product under test when it is on the back and when it is flipped to the front. Specifically, the measurement mark is a sheet-like body with through holes. The through holes are circular, and the centers of the two through holes correspond to the reference points respectively. and The extraction of the center coordinates is very stable and repeatable, thus facilitating camera measurement by the image measuring instrument and improving the accuracy of reference point measurement. During flipping, the metal sheet moves synchronously along with the image, and both the front and back sides of the sheet are easily positioned and their coordinates measured by the camera, ensuring the consistency of measurement data after flipping the product under test.

[0041] Step 120: Control the product under test to flip up and down; In some implementations, an automatic flipping mechanism integrated into the image measuring instrument controls the product under test to flip vertically, specifically by 180°, ensuring a smooth transition from the back to the front without any tilt. If the product is tilted during the flipping process, perspective distortion will occur in the camera image, for example, measuring a perfect circle as an ellipse, thus introducing measurement error. The automatic flipping mechanism can be implemented using a robot gripper or a dedicated flipping table, depending on the product characteristics, ensuring the product accurately transitions from a back posture to a front posture for subsequent frontal image data acquisition by the image measuring instrument's camera.

[0042] In some implementations, the flipping axis can be any feature axis of the product under test itself to achieve flipping. Specifically, it can be the axis of any sidewall, the upper sidewall axis, the lower sidewall axis, or other axes of the product under test.

[0043] Step 130: Control the camera to measure the frontal reference point based on the machine coordinate system. and Two-dimensional coordinates, to obtain In the third coordinate of the machine coordinate system and In the fourth coordinate of the machine coordinate system; wherein, the back reference point and After the product under test is flipped over, the corresponding front reference points are as follows: and ; In some implementations, the camera of the image measuring instrument measures a frontal reference point of the product under test. and The coordinate system used is the machine coordinate system set by the camera.

[0044] In some implementations, for ease of measurement, a front reference point is determined by measuring the center of a circular through-hole on the sidewall of the product under test. and The coordinates.

[0045] Step 140: Obtain affine transformation parameters based on the first coordinate, second coordinate, third coordinate, and fourth coordinate. These affine transformation parameters are used to transform the back face reference point. and Mapped to the frontal reference point and .

[0046] In some other implementations, the affine transformation parameters are obtained by calculating matrices, referencing... Figure 3 The calculation method includes the following steps: Step 141: Determine the matrix form of the affine transformation parameters as follows: ; The transformation formula is determined as follows: =a*x+b*y+ , =c*x+d*y+ ; Where a, b, c, and d are parameters that control scaling, rotation, and shearing. and To control the parameters of translation, The original two-dimensional coordinates, The coordinates are two-dimensional coordinates after affine transformation; The first coordinate in the back coordinate system is represented as ( , ), The second coordinate in the back coordinate system is represented as ( , ), The third coordinate in the machine coordinate system is represented as , The fourth coordinate in the machine coordinate system is represented as ( , ); Step 142: Calculate the original vector =( , )-( , ), target vector ( , ); Step 143: Calculate the original vector Rotate to target vector rotation angle The values ​​of the cosine and sine functions: =( ) / ( ), ( ) / ( ); Calculate the scaling factor: / ; Construct the rotation and scaling matrix: ; in, The parameter a corresponds to the affine transformation moment matrix. Corresponding parameter b, Corresponding parameter c, Corresponding parameter d; Step 144: Calculate the translation components and : =( , ) x- +b ]; =( , ) y- + ].

[0047] Step 145: Obtain the affine transformation moment matrix.

[0048] Step 150: Based on the aforementioned back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates.

[0049] In some implementations, a mirror reference point is obtained. and The specific steps for two-dimensional coordinates are as follows: Get the back reference point and The equation of the line that bisects the perpendicular bisector of the line connecting the two points is: Ax + By + C = 0; like The first coordinate in the back coordinate system is represented as ( , ), The second coordinate in the back coordinate system is represented as ( , (Reference point on the back) and The equation of the line that bisects the perpendicular bisector of the line is A = B=1; C= [ +( )· ]; like The coordinates are ( , ),but The coordinate formula is: ( -2A* ; like The coordinates are ( , ),but The coordinate formula is: ( -2A* ,

[0050] in + B + C) / (A² + B²), = (A + B + C) / (A² + B²).

[0051] In some implementations, a mirror reference point is obtained. and The specific steps for two-dimensional coordinates are as follows: Based on the reference point on the back and Construct a straight line by connecting coordinates, and then construct the midpoint on that line. Rotate the line 90° around this midpoint to obtain a mirror axis of symmetry. Then, mirror the back reference point based on this axis of symmetry. and Obtain the mirror reference point and Two-dimensional coordinates.

[0052] Step 160: Based on the mirror reference point and The two-dimensional coordinates are used to obtain the corresponding reference point on the front side through the affine transformation parameters. and The two-dimensional coordinates, based on the reference point corresponding to the front face. and A two-dimensional coordinate system is established for positive evaluation, which is used to evaluate positive measurement elements.

[0053] In some implementations, the front measurement element includes the center point of the needle tip to be evaluated on the front. When the product to be tested is flipped 180° from the back to the front, the camera of the image measuring instrument measures the coordinates of the center point of the needle tip to be evaluated based on the front evaluation coordinate system, and obtains the measured coordinates of the center point of the needle tip.

[0054] In some implementations, the specific evaluation method is as follows: the theoretical coordinates of the center point of the needle tip to be tested and the range of needle tip tolerance deviation values ​​are both provided by the customer who put forward the product testing requirements. The testing drawings provided by the customer contain these data. The deviation is calculated based on the measured coordinates and theoretical coordinates of the needle tip center point. Specifically, it can be calculated using the Euclidean distance formula to determine whether the deviation is within the tolerance deviation range. This is used to measure the difference between the needle tip center point on the actual processed product and the theoretical coordinates of the needle tip center point on the drawing, ensuring the accuracy and reliability of the needle tip during assembly.

[0055] In some embodiments, step 140 "obtains affine transformation parameters based on the first coordinate, second coordinate, third coordinate, and fourth coordinate, the affine transformation parameters being used to transform the back face reference point..." and Mapped to the frontal reference point and And in step 160, "based on the mirror reference point" and The two-dimensional coordinates are used to obtain the corresponding reference point on the front side through the affine transformation parameters. and Two-dimensional coordinates. This can be achieved through geometric construction, including the following methods: Based on the reference point on the back and Connect the lines to construct a straight line, construct the midpoint on the straight line, and rotate the straight line 90° around the midpoint to obtain a mirror axis of symmetry; Mirror the back reference point according to the axis of symmetry. and Obtain mirror reference point and ; Based on the mirror reference point and positive reference points Construct a mirror reference point using two-dimensional coordinates To the positive reference point The translation vector V is based on the mirror reference point obtained in step 150. and Constructing a mirror reference point using two-dimensional coordinates and Mirror the reference point and and mirror reference point and The translation is performed along the direction defined by vector V, with the translation distance being the magnitude of vector V, to obtain the translation reference point. and and translation reference point and ; Based on the translation reference point and and positive reference points and Construct a translation reference point using two-dimensional coordinates. To the translation reference point straight line and positive reference points and straight line ; According to the straight line and straight line Construct a straight line to the straight line rotation angle Translation reference point and and translation reference point and With a positive reference point Based on the rotation angle Rotate to obtain the reference point corresponding to the front face. and Frontal corresponding reference point as well as .

[0056] In some implementations, a straight line is constructed. to the straight line rotation angle Specifically, using straight lines and straight line The intersection point O is taken as the vertex, and with As the starting edge, For the terminating edge, rotate by angle for Rotate clockwise or counterclockwise to The angle.

[0057] refer to Figure 4 This application also provides an image measuring instrument 200, comprising: At least one processor; and, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the above-described front-side measurement element evaluation method based on a back-side reference.

[0058] In some implementations, the processor 210 and the memory 220 can be connected via a bus or other means. Figure 4 Taking the example of a connection between China and Israel via a bus.

[0059] In some implementations, the processor 210 controls the camera of the image measuring instrument 200 to measure two reference points on the back of the product under test based on a machine coordinate system. and Two-dimensional coordinates, based on the reference point and A back face coordinate system is established using two-dimensional coordinates, and two reference points on the back face are measured based on this coordinate system. and ,get The first coordinate in the back coordinate system and The second coordinate in the back coordinate system; control the product under test to flip; control the camera to measure the front reference point based on the machine coordinate system. and Two-dimensional coordinates, to obtain In the third coordinate of the machine coordinate system and In the fourth coordinate of the machine coordinate system; wherein, the back reference point and After the product under test is flipped over, the corresponding front reference points are as follows: and The affine transformation parameters are obtained based on the first, second, third, and fourth coordinates. These parameters are used to transform the back face reference point. and Mapped to the frontal reference point and According to the aforementioned back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates; based on the mirror reference point and The two-dimensional coordinates are used to obtain the corresponding reference point on the front side through the affine transformation parameters. and The two-dimensional coordinates, based on the reference point corresponding to the front face. and A two-dimensional coordinate system is established for evaluating frontal measurement elements. In some embodiments, the memory 220 serves as a non-volatile computer-readable storage medium, used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as the program instructions / modules for the frontal measurement element evaluation method based on a back-side reference in this application embodiment. The processor 210 executes various functional applications and data processing of the line scan image measuring instrument by running the non-volatile software programs, instructions, and modules stored in the memory 220, thereby implementing the frontal measurement element evaluation method based on a back-side reference in the above method embodiment.

[0060] In some embodiments, memory 220 may include a program storage area and a data storage area, wherein the program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the image measuring instrument, etc. Furthermore, memory 220 may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 220 may optionally include memory remotely located relative to processor 210, and this remote memory may be connected to the controller via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0061] In some implementations, one or more modules are stored in memory 220 and, when executed by one or more processors 210, perform the front-side measurement element evaluation method based on a back-side reference in any of the above method embodiments, for example, performing the above-described... Figure 1 Steps 110 to 160 in the method.

[0062] refer to Figure 5 This application embodiment also provides a computer-readable storage medium 300, on which program code 310 is stored for each step according to the embodiments of this application. When the program code is executed by a processor, it implements the steps of the above-described front measurement element evaluation method based on a back reference, including: controlling a camera to measure two reference points on the back of the product under test based on a machine coordinate system. and Two-dimensional coordinates, based on the reference point and A back face coordinate system is established using two-dimensional coordinates, and two reference points on the back face are measured based on this coordinate system. and ,get The first coordinate in the back coordinate system and The second coordinate in the back coordinate system Control the product under test to flip over; control the camera to measure the front reference point based on the machine coordinate system. and Two-dimensional coordinates, to obtain In the third coordinate of the machine coordinate system and In the fourth coordinate of the machine coordinate system; wherein, the back reference point and After the product under test is flipped over, the corresponding front reference points are as follows: and The affine transformation parameters are obtained based on the first, second, third, and fourth coordinates. These parameters are used to transform the back face reference point. and Mapped to the frontal reference point and According to the aforementioned back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates; based on the mirror reference point and The two-dimensional coordinates are used to obtain the corresponding reference point on the front side through the affine transformation parameters. and The two-dimensional coordinates, based on the reference point corresponding to the front face. and A two-dimensional coordinate system is established for positive evaluation, which is used to evaluate positive measurement elements.

[0063] In some embodiments, the computer-readable storage medium 300 may be an electronic memory such as flash memory, EEPROM (Electrically Erasable Programmable Read-Only Memory), EPROM, hard disk, or ROM. Optionally, the computer-readable storage medium includes a non-transitory computer-readable storage medium. The computer-readable storage medium 300 has storage space for program code 310 that performs any of the method steps of the control method described above. This program code can be read from or written to one or more computer program products. The program code may, for example, be compressed in a suitable form.

[0064] In summary, this application provides a method, apparatus, and medium for evaluating the positional accuracy of a front-side pin tip based on a back-side reference. The method includes: controlling a camera based on a machine coordinate system to measure two reference points on the back side of the product under test. and Two-dimensional coordinates, based on the reference point and A back face coordinate system is established using two-dimensional coordinates, and two reference points on the back face are measured based on this coordinate system. and ,get The first coordinate in the back coordinate system and The second coordinate in the back coordinate system; Control the product under test to flip over; Control the camera to measure the frontal reference point based on the machine coordinate system. and Two-dimensional coordinates, to obtain In the third coordinate of the machine coordinate system and In the fourth coordinate of the machine coordinate system; wherein, the back reference point and After the product under test is flipped over, the corresponding front reference points are as follows: and ; The affine transformation parameters are obtained based on the first, second, third, and fourth coordinates. These affine transformation parameters are used to transform the back reference point. and Mapped to the frontal reference point and

[0065] According to the back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates; According to the mirror reference point and The two-dimensional coordinates are used to obtain the corresponding reference point on the front side through the affine transformation parameters. and The two-dimensional coordinates, based on the reference point corresponding to the front face. and A two-dimensional coordinate system is established for positive evaluation, which is used to evaluate positive measurement elements.

[0066] This application can map the back-side measurement elements of a product under test to the corresponding positions on the front side through affine transformation parameters, thereby evaluating the data of the front-side measurement elements under the reference of the transformed front side.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for evaluating front-side measurement elements based on a back-side reference, characterized in that, The method includes: The camera is controlled based on the machine coordinate system to measure two reference points on the back of the product under test. and Two-dimensional coordinates, based on the reference point and A back face coordinate system is established using two-dimensional coordinates, and two reference points on the back face are measured based on this coordinate system. and ,get The first coordinate in the back coordinate system and The second coordinate in the back coordinate system; Control the product under test to flip up and down; Control the camera to measure the frontal reference point based on the machine coordinate system. and Two-dimensional coordinates, to obtain In the third coordinate of the machine coordinate system and In the fourth coordinate of the machine coordinate system, where the back reference point is... and After the product under test is flipped over, the corresponding front reference points are as follows: and ; The affine transformation parameters are obtained based on the first, second, third, and fourth coordinates. These affine transformation parameters are used to transform the back reference point. and Mapped to the frontal reference point and ; According to the back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates; According to the mirror reference point and The two-dimensional coordinates are used to obtain the corresponding reference point on the front side through the affine transformation parameters. and The two-dimensional coordinates, based on the reference point corresponding to the front face. and A two-dimensional coordinate system is established for positive evaluation, which is used to evaluate positive measurement elements.

2. The method for evaluating front-side measurement elements based on a back-side reference according to claim 1, characterized in that: The product under test is provided with a measurement mark, and the measurement mark is provided with a reference point. The measurement mark can be captured by a camera when the product under test is on the back and / or flipped to the front.

3. The method for evaluating front-side measurement elements based on a back-side reference according to claim 2, characterized in that: The measurement markers are two sheet-like bodies with through holes, each hole being circular, and the centers of the two through holes corresponding to reference points. and .

4. The method for evaluating front-side measurement elements based on a back-side reference according to claim 1, characterized in that: The affine transformation parameters are obtained based on the first, second, third, and fourth coordinates, including: The matrix form for determining the affine transformation parameters is as follows: ; The transformation formula is determined as follows: =a*x+b*y+ , =c*x+d*y+ ; Where a, b, c, and d are parameters that control scaling, rotation, and shearing. and To control the parameters of translation, The original two-dimensional coordinates, The coordinates are two-dimensional coordinates after affine transformation; The first coordinate in the back coordinate system is represented as ( , ), The second coordinate in the back coordinate system is represented as ( , ), The third coordinate in the machine coordinate system is represented as , The fourth coordinate in the machine coordinate system is represented as ( , ); Calculate the original vector = ( , )-( , ), target vector ( , ); Calculate the original vector Rotate to target vector rotation angle The values ​​of the cosine and sine functions: =（ ） / （ ）， （ ） / （ ）； Calculate the scaling factor: / ; Construct the rotation and scaling matrix: ; in, The parameter a corresponds to the affine transformation matrix. Corresponding parameter b, Corresponding parameter c, Corresponding parameter d; Calculate translation components and : =( , ) x- +b ]; =（ ， ） y- + ]； The affine transformation matrix is ​​obtained.

5. The method for evaluating front-side measurement elements based on a back-side reference according to claim 1, characterized in that: The affine transformation parameters are obtained based on the first, second, third, and fourth coordinates. These affine transformation parameters are used to transform the back reference point. and Mapped to the frontal reference point and According to the mirror reference point and The two-dimensional coordinates are used to obtain the corresponding reference point on the front side through the affine transformation parameters. and Two-dimensional coordinates, including: Based on the reference point on the back and Connect the lines to construct a straight line, construct the midpoint on the straight line, and rotate the straight line 90° around the midpoint to obtain a mirror axis of symmetry; Mirror the back reference point according to the axis of symmetry. and Obtain mirror reference point and ; Based on the mirror reference point and positive reference points Construct a mirror reference point using two-dimensional coordinates To the positive reference point The translation vector V, based on the mirror reference point and Constructing a mirror reference point using two-dimensional coordinates and Mirror the reference point and and mirror reference point and The translation is performed along the direction defined by vector V, with the translation distance being the magnitude of vector V, to obtain the translation reference point. and and translation reference point and ; Based on the translation reference point and and positive reference points and Construct a translation reference point using two-dimensional coordinates. To the translation reference point straight line and positive reference points and straight line ; According to the straight line and straight line Construct a straight line to the straight line rotation angle Translation reference point and and translation reference point and With a positive reference point Based on the rotation angle Rotate to obtain the reference point corresponding to the front face. and Frontal corresponding reference point as well as .

6. The method for evaluating front-side measurement elements based on a back-side reference according to claim 1, characterized in that: According to the back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates, including: Based on the reference point on the back and Construct a straight line by connecting coordinates, and then construct the midpoint on that line. Rotate the line 90° around this midpoint to obtain a mirror axis of symmetry. Then, mirror the back reference point based on this axis of symmetry. and Obtain the mirror reference point and Two-dimensional coordinates.

7. The method for evaluating front-side measurement elements based on a back-side reference according to claim 1, characterized in that: According to the back reference point and The perpendicular bisector of the line determines the mirror symmetry axis. Based on the mirror symmetry axis and the reference point... and Obtain the mirror reference point from the two-dimensional coordinates. and Two-dimensional coordinates, including: Get the back reference point and The equation of the line that bisects the perpendicular bisector of the line connecting the two points is: Ax + By + C = 0; like The first coordinate in the back coordinate system is represented as ( , ), The second coordinate in the back coordinate system is represented as ( , (Reference point on the back) and The equation of the line that bisects the perpendicular bisector of the line is A = B=1; C= [ +( )· ]; like The coordinates are ( , ),but The coordinate formula is: ( -2A* , ); like The coordinates are ( , ),but The coordinate formula is: ( -2A* , ); where =(A + B + C) / (A² + B²), = (A + B + C) / (A² + B²).

8. The method for evaluating front-side measurement elements based on a back-side reference according to claim 1, characterized in that: Based on the aforementioned front-facing reference point and Establish a positive evaluation coordinate system, which is used to evaluate positive measurement elements, including: When the product under test is flipped 180° from the back to the front, the camera of the image measuring instrument measures the coordinates of the center point of the needle tip based on the front evaluation coordinate system, and obtains the measured coordinates of the center point of the needle tip. Obtain the theoretical coordinates of the center point of the needle tip to be tested and the range of the needle tip tolerance deviation value. Calculate the deviation based on the measured coordinates and theoretical coordinates of the needle tip center point, and determine whether the deviation falls within the tolerance deviation value range.

9. An image measuring instrument, characterized in that: include: At least one processor; as well as, A memory communicatively connected to the at least one processor; wherein, The memory stores instructions executable by the at least one processor, which, when executed by the at least one processor, enables the at least one processor to perform the front-side measurement element evaluation method based on a back-side reference as described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the front-side measurement element evaluation method based on a back-side reference as described in any one of claims 1 to 8.

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