A method, system, medium and product for error identification of a three - coordinate measuring machine

Abstract

The present invention discloses a method, system, medium and product for error identification of a coordinate measuring machine. The present invention includes obtaining the measurement coordinates during the movement of the space diagonal of a standard sphere in a preset body space and establishing an error equation for each measurement position, which includes the influence caused by the probe error and the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error; after expanding the error equation, neglecting the second-order small quantities to construct a linear equation system in matrix form for multiple measurement positions; subtracting the linear equation systems in matrix form of adjacent measurement positions to obtain a linear equation system in matrix form of the differences between adjacent measurement positions, thereby decoupling the influence caused by the probe error and obtaining the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error, as well as the geometric error and the perpendicularity error. The purpose of the present invention is to simply and reliably achieve the accurate identification of the geometric error of the coordinate measuring machine in order to achieve the precise compensation of the geometric error of the coordinate measuring machine.

Description

Technical Field

[0001] The present invention relates to the technical field of error compensation of coordinate measuring machines, and particularly relates to a method, a system, a medium and a product for identifying errors of a coordinate measuring machine. Background Art

[0002] A coordinate measuring machine is a high-efficiency precision measuring system, featuring high precision, fast measuring speed and strong adaptability. It plays a crucial role in modern production manufacturing, as well as in fields such as aviation and aerospace, and is an indispensable basic measuring device in the advanced manufacturing field. In addition, it also plays a key role in quality inspection and control in the civilian industry, capable of performing spatial three-dimensional coordinate measurement on geometric elements, curves and surfaces of various parts, and supporting on-line inspection and automated measurement. With the progress of technology and the development of ultra-precision machining technology, the requirement for the measuring accuracy of coordinate measuring machines is constantly increasing. Quickly and accurately calibrating a coordinate measuring machine, detecting and compensating its errors is an important method to improve its measuring accuracy and also a cost-effective technical means. A coordinate measuring machine has three mutually perpendicular axes, and each axis has six basic errors: three linear displacement errors and three angular errors. Plus the perpendicularity errors between the three axes, there are a total of 21 geometric error sources. The detection methods for geometric errors can be divided into two categories: one is the direct method, which uses instruments such as laser interferometers to directly detect each individual geometric error of the coordinate measuring machine; the other is the indirect method, which uses sphere arrays, sphere plates, etc. to detect the comprehensive motion errors of the coordinate measuring machine, and then decomposes the original geometric errors. Directly measuring individual geometric errors with a laser interferometer can detect these error values with relatively high accuracy. The disadvantage is that the laser interferometer is expensive, has high requirements for environmental conditions and the technical level of the operator, and cannot achieve the detection of all 21 geometric errors. Physical references such as sphere arrays and sphere plates solve for each individual error by placing them at multiple positions, but spherical errors, probe errors, calibration errors, etc. are all included in the physical references such as sphere plates and sphere arrays during the measurement process, and some references also need to be periodically calibrated, which cannot meet the requirements of higher-precision measurement. From the above analysis, it can be seen that there is currently no very simple and reliable method for identifying errors of coordinate measuring machines. For this reason, the identification of errors of coordinate measuring machines remains a research hotspot. Summary of the Invention

[0003] The technical problem to be solved by the present invention: Aiming at the above problems of the prior art, the present invention provides a method, a system, a medium and a product for identifying errors of a coordinate measuring machine. The present invention aims to simply and reliably achieve accurate identification of the geometric errors of a coordinate measuring machine for realizing precise compensation of the geometric errors of the coordinate measuring machine.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0005] A method for identifying errors of a three - coordinate measuring machine, comprising the following steps:

[0006] S1, obtain the measurement coordinates of a standard sphere at multiple measurement positions through the probe of the three - coordinate measuring machine during the movement of the space diagonal in the preset body space, and establish an error equation for each measurement position, which includes the influence caused by the probe error and the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error;

[0007] S2, after expanding the error equation, ignore the second - order small quantities to construct a linear equation system in matrix form, and combine multiple measurement positions to obtain a linear equation system in matrix form for multiple measurement positions:

[0008] S3, subtract the linear equation system in matrix form of adjacent measurement positions in the linear equation system in matrix form of multiple measurement positions to obtain a linear equation system in matrix form of the difference between adjacent measurement positions, so that the radius R of the standard sphere and the influence caused by the probe error are cancelled as "common - mode inputs" to decouple the influence caused by the probe error, and obtain the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error, as well as the geometric error and the perpendicularity error.

[0009] Optionally, the functional expression of the error equation in step S1 is:

[0010] ,

[0011] In the above formula, is the measurement coordinate of the three - coordinate measuring machine, is the nominal coordinate position where the center of the known standard sphere is placed, is the known error value, is the known radius of the standard sphere, is the spatial motion error composed of geometric error and perpendicularity error, is the influence caused by the probe error, are the angles between the normal direction and the x, y, z coordinate axes respectively and remain unchanged during the movement of the space diagonal, and there are:

[0012] ,

[0013] ,

[0014] ,

[0015] Among them, , , , , and Six geometric errors with respect to the x-axis respectively, and and and and and Six geometric errors with respect to the y-axis respectively, and and and and Six geometric errors with respect to the z-axis respectively, Three constant perpendicularity errors, The probe coordinates.

[0016] Optionally, step S2 includes:

[0017] S2.1, After expanding the error equation and neglecting the second-order small quantities, the following error equation is obtained:

[0018] ,

[0019] S2.2, Construct a linear equation in matrix form as shown below from the error equation after expanding and neglecting the second-order small quantities:

[0020] ,

[0021] In the above formula, The error value composed of the polynomial coefficients of the geometric errors and the perpendicularity errors, A The Jacobian matrix, , B The data value on the right side of the error equation after expanding and neglecting the second-order small quantities;

[0022] S2.3, Combine multiple measurement positions to obtain a system of linear equations in matrix form for multiple measurement positions:

[0023] ,

[0024] In the above formula, to Are the Jacobian matrices at N positions during the spatial diagonal movement of the standard sphere in the preset body space respectively, to Are the data values on the right side of the error equation after expanding and neglecting the second-order small quantities corresponding to N positions during the spatial diagonal movement of the standard sphere in the preset body space respectively.

[0025] Optionally, step S3 includes:

[0026] S3.1. Subtract the linear equations in matrix form for adjacent measurement positions in the linear equations in matrix form for multiple measurement positions to obtain a linear equation in matrix form for the differences between adjacent measurement positions:

[0027] ,

[0028] S3.2. Obtain an error value composed of the polynomial coefficients of geometric errors and perpendicularity errors from the linear equation in matrix form for the differences between adjacent measurement positions , and obtain geometric errors and perpendicularity errors.

[0029] Optionally, the geometric error is a cubic polynomial, such that the error value composed of the polynomial coefficients of geometric errors and perpendicularity errors includes 54 polynomial coefficients of 18 geometric errors and 3 constant perpendicularity errors, for a total of 57 parameters to be solved.

[0030] Optionally, after step S3, it further includes substituting the obtained geometric errors and perpendicularity errors into the error equation to obtain the on the right side of the error equation, and then combining with the radius of the standard sphere to obtain the influence caused by probe errors ; for the influence caused by probe errors perform surface fitting or neural network modeling and learning to obtain the probe error distribution in continuous space.

[0031] Optionally, the standard sphere is a standard sphere with a nanoscale sphericity error level, the standard sphere is made of microcrystalline glass material, and the preparation of the standard sphere includes: polishing the standard sphere made of microcrystalline glass material, and then measuring the nanoscale sphericity error of the standard sphere by a laser wavefront interferometer. If the nanoscale sphericity error does not meet the requirements, continue to polish the standard sphere made of microcrystalline glass material until the nanoscale sphericity error meets the requirements.

[0032] In addition, the present invention also provides a coordinate measuring machine error identification system, including a microprocessor and a memory connected to each other, and the microprocessor is programmed or configured to execute the coordinate measuring machine error identification method.

[0033] In addition, the present invention also provides a computer-readable storage medium, in which a computer program or instruction is stored, and the computer program or instruction is programmed or configured to execute the coordinate measuring machine error identification method through a processor.

[0034] In addition, the present invention also provides a computer program product, including a computer program or instruction, and the computer program or instruction is programmed or configured to execute the coordinate measuring machine error identification method through a processor.

[0035] Compared with the prior art, the present invention can mainly achieve the following beneficial effects: By obtaining the measurement coordinates of a standard sphere during the movement of the space diagonal in a preset body space through a coordinate measuring machine and establishing an error equation as shown below, after expanding the error equation, ignoring second-order small quantities, a linear equation system in matrix form as shown below is constructed. Subtracting adjacent positions in the linear equation system in matrix form at N positions, a linear equation system in matrix form of the adjacent differences at N positions is obtained, so that the radius of the standard sphere R and the influence caused by the probe error are cancelled out as "common-mode inputs", so that the influence caused by the probe error can be decoupled. Moreover, due to the increase in the amount of data at multiple positions and the relatively complex distribution, the problem of underdetermined Jacobian matrix can be solved, so that the geometric error of the coordinate measuring machine can be accurately identified simply and reliably for realizing precise compensation of the geometric error of the coordinate measuring machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of the basic process of the method according to an embodiment of the present invention.

[0037] Figure 2 is a schematic diagram of the structure of a coordinate measuring machine according to an embodiment of the present invention.

[0038] Figure 3 is a schematic diagram of the translation measurement of a standard sphere according to an embodiment of the present invention.

[0039] Figure 4 is a schematic diagram of the process of moving along the space diagonal according to an embodiment of the present invention.

[0040] Figure 5 is the setting result of the space motion error according to an embodiment of the present invention, where (a) is the space motion error in the x-axis direction, (b) is the space motion error in the y-axis direction, and (c) is the space motion error in the z-axis direction.

[0041] Figure 6 is the identification result of the space motion error according to an embodiment of the present invention, where (a) is the space motion error in the x-axis direction, (b) is the space motion error in the y-axis direction, and (c) is the space motion error in the z-axis direction. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings in the embodiments of the present invention.

[0043] As Figure 1 shown, the error identification method for a coordinate measuring machine in this embodiment includes the following steps:

[0044] S1. Obtain the measurement coordinates of the standard ball at multiple measurement positions through the probe of the coordinate measuring machine during the movement of the space diagonal in the preset volume space, and establish an error equation for each measurement position, which includes the influence caused by the probe error and the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error.

[0045] S2. After expanding the error equation, ignore the second-order small quantities to construct a linear equation system in matrix form, and combine multiple measurement positions to obtain a linear equation system in matrix form for multiple measurement positions:

[0046] S3. Subtract the linear equation system in matrix form of adjacent measurement positions from the linear equation system in matrix form of multiple measurement positions to obtain a linear equation system in matrix form of the differences between adjacent measurement positions, so that the radius of the standard ball R and the influence caused by the probe error are canceled as "common-mode inputs" to decouple the influence caused by the probe error, and obtain the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error, as well as the geometric error and the perpendicularity error.

[0047] Since the FXYZ-type coordinate measuring machine with a moving bridge structure is a classic structure in coordinate measuring machines, in this embodiment, the FXYZ-type coordinate measuring machine with the moving bridge structure shown in Figure 2 is used as the object for analysis. A moving bridge that can move along the X-axis direction is provided on the base of this coordinate measuring machine and is equipped with an X grating scale (used to detect the displacement in the X-axis direction). A Y-slider that can slide along the Y direction and the corresponding Y-grating scale (used to detect the displacement in the Y-axis direction) are provided on the moving bridge. A measuring column that can move along the Z direction and the corresponding grating scale (Z-grating scale, used to detect the displacement in the Z-axis direction) are provided on the Y-slider. During processing, the workpiece is located on the base of the coordinate measuring machine. By adjusting the movement of the moving bridge, Y-slider and measuring column, the space diagonal movement of the standard ball in the preset volume space can be achieved. As shown in Figure 2 Four coordinate systems, OXYZ and O i X i Y i Z i (i = 1, 2, 3), are established on the four relative moving parts. When the four relative moving parts are at the origin, it is assumed that the origins and coordinate axes of the four coordinate systems coincide. For the probe, it is not at the origin position and has coordinates ([[]] in the O3X3Y3Z3 coordinate system x p , y p , z p ), and this coordinate is determined by the structure of the measuring machine and the position of the Z-axis grating scale. When the moving bridge translates a distance x along the X direction, Denote the displacement errors along the X, Y, and Z axes during X-axis movement as the displacement error along the X-axis. Then this displacement ( )can be expressed by the following formula:

[0048] , (1)

[0049] Denote as the angular errors about the X, Y, and Z axes during X-axis movement. Then the rotation matrix during movement along the X-axis can be expressed by the following formula:

[0050] , (2)

[0051] According to the small-angle assumption, the angular errors generated during translation are all small-angle errors. Then Equation (2) can be written as:

[0052] , (3)

[0053] Similarly, the translation amounts , , the rotation matrix during movement along the X-axis, and the rotation matrix during movement along the X-axis can be obtained.

[0054] When the probe tip P( x p , y p , z p ) translates along the X, Y, and Z axes by x , y , z distances respectively. If there are no geometric errors in the measuring machine, then the probe will move to P ideal ( x + x p , y + y p , z + z p ). However, under the influence of geometric errors, the probe tip will move to P error ( x’, y’, z’ ). Therefore, the difference between P ideal and P error is the measurement error E ( Δx, Δy, Δz ). To obtain the position P error of P in the coordinate system OXYZ, the positions of P in O3X3Y3Z3, O2X2Y2Z2, and O1X1Y1Z1 will be obtained respectively. The position of P in O3X3Y3Z3 is denoted as O3P:

[0055] , (4)

[0056] Then, there are two steps to obtain the position of the stylus tip P in the coordinate system O2X2Y2Z2. The first step is to rotate the three axes of O3X3Y3Z3 to be parallel to the three axes of O2X2Y2Z2, and the second step is to move the origin O3 to coincide with the origin O2. Therefore, the position of P in the coordinate system O2X2Y2Z2 can be defined as:

[0057] , (5)

[0058] where the matrix O2O3 is the linear motion matrix for translation along the Z-axis, and the matrix R( z ) is the rotation matrix during the translation along the Z-axis, are three constant perpendicularity errors, which are expressed by the following formulas respectively:

[0059] , (6)

[0060] , (7)

[0061] Similarly, in order to obtain the position of P in the coordinate system O1X1Y1Z1, rotate the three coordinate axes of O2X2Y2Z2 to be parallel to the three axes of O1X1Y1Z1, and move the origin O2 to coincide with the origin O1. Therefore, the position of P in the coordinate system O1X1Y1Z1 can be expressed as:

[0062] , (8)

[0063] where the matrix O1O2 is the linear motion matrix for translation along the Y-axis, and the matrix R( y ) is the rotation matrix during the translation along the Y-axis. They are expressed by formulas (9) and (10) respectively:

[0064] , (9)

[0065] , (10)

[0066] Similarly, in order to obtain the position of P in the coordinate system OXYZ, rotate the three coordinate axes of O1X1Y1Z1 to be parallel to the three axes of OXYZ, and move the origin O1 to coincide with the origin O. Therefore, the position of P in the coordinate system OXYZ can be expressed as:

[0067] , (11)

[0068] The matrix OO1 and the matrix R( x)They are represented by formulas (1) and (3) respectively. After substituting formulas (1)-(10) into formula (11), we can get:

[0069] , (12)

[0070] In the above geometric error model, for the convenience of analysis, it is assumed that the straightness error and angular error of each moving axis are functions of the corresponding displacement amounts (x, y, z), and each individual error can be fitted with a corresponding polynomial. In this embodiment, the geometric error is fitted with a cubic polynomial. Taking the X-axis as an example, the 6 geometric error parameters of a single axis are parameterized as follows:

[0071] , (13)

[0072] Similarly, the motion errors of the Y-axis and Z-axis can be parameterized with reference to formula (13). Adding the three constant perpendicularity errors , there are a total of 57 parameters to be solved. That is, in this embodiment, the geometric error is a cubic polynomial, so that the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error includes 54 polynomial coefficients of 18 geometric errors and 3 constant perpendicularity errors, a total of 57 parameters to be solved.

[0073] In this embodiment, the standard ball is a standard ball with a nanometer-level sphericity error, and the standard ball is made of glass-ceramics material. The advantages compared with the standard ball made of traditional ceramic material are as follows: The standard ball made of glass-ceramics material can obtain an extremely high even nanometer-level sphericity error by modern polishing technology, and its ball diameter can be directly measured by a laser wavefront interferometer, achieving a very high measurement accuracy. As an alternative implementation manner, the preparation of the standard ball in this embodiment includes: polishing the standard ball made of glass-ceramics material, and then measuring the nanometer-level sphericity error of the standard ball by a laser wavefront interferometer. If the nanometer-level sphericity error does not meet the requirements, continue to polish the standard ball made of glass-ceramics material until the nanometer-level sphericity error meets the requirements.

[0074] As Figure 3 shown, assume that the nominal coordinate position where the center of the high-precision standard ball is placed is (which can be obtained by fitting the initial measurement data), the error value is , the sum of the measured ball radius and the standard ball radius is R , and the spatial motion error is . As Figure 4 shown, in this embodiment, the measurement coordinates of the standard ball at multiple measurement positions are obtained through the probe of the coordinate measuring machine during the spatial diagonal movement of the standard ball in the preset body space, that is, the measurement coordinates of multiple coordinate measuring machines , and the function expression of the error equation in step S1 of this embodiment is:

[0075] , (14)

[0076] In the above formula, is the measurement coordinate of the coordinate measuring machine, is the nominal coordinate position where the center of the known standard sphere is placed, is the known error value, is the radius of the known standard sphere, is the spatial motion error composed of geometric error and perpendicularity error, is the influence caused by the probe error, are the angles between the normal direction and the x, y, z coordinate axes respectively and remain unchanged during the movement of the space diagonal. As Figure 3 shown, and there are:

[0077] , (15)

[0078] , (16)

[0079] , (17)

[0080] Among them, , , , , and are respectively 6 geometric errors about the x-axis, , , , , and are respectively 6 geometric errors about the y-axis, , , , and are respectively 6 geometric errors about the z-axis, are 3 constant perpendicularity errors, is the probe coordinate.

[0081] In this embodiment, step S2 includes:

[0082] S2.1, After expanding the error equation and ignoring the second-order small quantities, the following error equation is obtained:

[0083] , (18)

[0084] S2.2, After expanding and ignoring the second-order small quantities, the following linear equation in matrix form is constructed for the error equation:

[0085] , (19)

[0086] In the above formula, is the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error, A is the Jacobian matrix, , B is the data value on the right side of the error equation after neglecting the second-order small quantity after expansion; however, there are still two problems in solving the above equations: Since the probe error is coupled in the measurement data during actual measurement, the equations cannot be solved; Since only the data at one position of the sphere is measured and the measurement data distribution is relatively single, the Jacobian matrix A in the above formula will be rank-deficient and it is impossible to obtain the accurate . In view of the above problems, in this embodiment, a method of moving the space diagonal of the standard sphere is proposed to identify the geometric error parameters. As Figure 4 shown, the standard spheres are evenly distributed on the space diagonal of the identified volume space. At the initial position, the range of the normal angle of the measurement area on the sphere surface is determined, and the measurement area at the subsequent position is kept consistent with it. The aim is to cancel the influence caused by the radius R of the standard sphere and the probe error as "common-mode input" to decouple the influence caused by the probe error;

[0087] S2.3, Combine multiple measurement positions to obtain a system of linear equations in matrix form for multiple measurement positions:

[0088] , (20)

[0089] In the above formula, ~ are the Jacobian matrices at N positions during the space diagonal movement of the standard sphere in the preset volume space respectively, ~ are the data values on the right side of the error equation after neglecting the second-order small quantity after expansion corresponding to N positions during the space diagonal movement of the standard sphere in the preset volume space respectively.

[0090] In this embodiment, step S3 includes:

[0091] S3.1, Subtract the system of linear equations in matrix form of adjacent measurement positions in the system of linear equations in matrix form of multiple measurement positions to obtain a system of linear equations in matrix form of the differences between adjacent measurement positions:

[0092] , (21)

[0093] Combining Equation (18) and Equation (20) and observing Equation (21), it can be found that in the data on the right side of the equation of Equation (21), the radius R and the influence of the probe error are cancelled out as "common-mode input". Therefore, the proposed method can decouple the influence brought by the probe error. Due to the increase in the amount of data at multiple positions and the relatively complex distribution, the problem of A rank deficiency of the Jacobian matrix can be solved;

[0094] S3.2. According to the linear equation system in matrix form of the difference between adjacent measurement positions, the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error is obtained, and the geometric error and the perpendicularity error are obtained.

[0095] After the error identification is completed, the distribution of the spatial motion error can be generated for error compensation. As an alternative implementation manner, after step S3 in this embodiment, it further includes substituting the obtained geometric error and perpendicularity error into the error equation to obtain the on the right side of the error equation, and then combining the radius of the standard sphere to obtain the influence caused by the probe error; for the influence caused by the probe error, surface fitting or neural network modeling learning is performed to obtain the probe error distribution in the continuous space.

[0096] In order to verify the error identification method of the coordinate measuring machine in this embodiment, relevant simulations are performed on the error identification method of the coordinate measuring machine in this embodiment, and the obtained results are as Figure 5 and Figure 6 shown. Figure 5 Shown is the distribution of the spatial motion error (in the range of 100×100×100 mm) caused by the 21 geometric errors set in the simulation. Measurement data is obtained by measuring the diagonal positions of the standard sphere, and its error parameters are obtained according to the error identification model. Figure 6 Shown is the three-dimensional spatial motion error distribution obtained by comprehensively combining the error parameters obtained by using the error identification method of the coordinate measuring machine in this embodiment. Comparing Figure 5 and Figure 6 it can be known that the error identification method of the coordinate measuring machine in this embodiment can well identify the distribution of the spatial error, and can simply and reliably achieve the accurate identification of the geometric error of the coordinate measuring machine, providing a good basis for subsequent error compensation.

[0097] In addition, the present invention also provides a coordinate measuring machine error identification system, including a microprocessor and a memory connected to each other, and the microprocessor is programmed or configured to execute the coordinate measuring machine error identification method.

[0098] In addition, the present invention also provides a computer-readable storage medium storing a computer program or instruction, which is programmed or configured to execute the error identification method of the coordinate measuring machine by a processor.

[0099] In addition, the present invention also provides a computer program product including a computer program or instruction, which is programmed or configured to execute the error identification method of the coordinate measuring machine by a processor.

[0100] Those skilled in the art should understand that the technical solutions provided by the embodiments of the present application can be in the form of a method, a system, or a computer program product. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes. The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks. These computer program instructions can also be stored in a computer-readable memory capable of guiding a computer or other programmable data processing devices to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device realizes the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks. These computer program instructions can also be loaded onto a computer or other programmable data processing devices, so that a series of operation steps are executed on the computer or other programmable devices to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable devices provide steps for realizing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0101] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A coordinate measuring machine error identification method, characterized in that: The steps include: S1, obtaining the measurement coordinates of the standard ball at multiple measurement positions by the three-dimensional coordinate measuring machine probe during the spatial diagonal movement of the standard ball in the preset body space, and establishing an error equation for each measurement position including the influence of the probe error and the error value composed of the polynomial coefficient of the geometric error and the verticality error; S2, after expanding the error equation, ignore the second-order small quantity to construct a linear equation system in matrix form, and combine multiple measurement positions to obtain a linear equation system in matrix form for multiple measurement positions: S3, subtracting the matrix-form linear equations of adjacent measurement positions from the matrix-form linear equations of the plurality of measurement positions to obtain the matrix-form linear equations of the differences of adjacent measurement positions, so that the radius of the standard sphere R The influence caused by the probe error is offset as a "common mode input" to decouple the influence caused by the probe error, and an error value composed of the polynomial coefficient of the geometric error and the perpendicularity error as well as the geometric error and the perpendicularity error is obtained; The functional expression of the error equation in step S1 is: ， In the above formula, is the measurement coordinate of the coordinate measuring machine, The nominal coordinate position of the center of a known standard sphere, is a known error value, is the radius of the known standard sphere, is the spatial motion error composed of geometric error and verticality error, The influence of the probe error, are the angles between the normal direction and the x, y, and z coordinate axes, respectively, and remain unchanged during the diagonal movement in space, and: ， ， ， in, , , , , and They are the six geometric errors about the x-axis, , , , , and They are the six geometric errors about the y-axis, , , , ,and They are the six geometric errors about the z-axis, are three constant verticality errors, is the probe coordinate.

2. The error identification method of a three-dimensional coordinate measuring machine according to claim 1, characterized in that: Step S2 includes: S2.1, expand the error equation and ignore the second-order small quantity to obtain the error equation shown in the following formula: ， S2.2, after expanding and ignoring the second-order small quantity, the error equation is constructed into a linear equation in the matrix form shown below: ， In the above formula, is the error value composed of the polynomial coefficients of the geometric error and the perpendicularity error, A is the Jacobian matrix, , B is the data value on the right side of the error equation after expansion and neglecting the second-order small quantity; S2.3, multiple measurement positions are combined to obtain a linear equation system in matrix form for multiple measurement positions: ， In the above formula, ~ are the Jacobian matrices of the N positions of the standard ball during its diagonal movement in the preset volume space, ~ They are respectively the data values ​​on the right side of the error equation corresponding to the N positions of the standard ball in the process of spatial diagonal movement in the preset volume space after the second-order small quantity is ignored after expansion.

3. The error identification method of a three-dimensional coordinate measuring machine according to claim 2, characterized in that: Step S3 includes: S3.1, subtract the matrix-form linear equations of adjacent measurement positions from the matrix-form linear equations of multiple measurement positions to obtain the matrix-form linear equations of the differences between adjacent measurement positions: ， S3.2, according to the linear equation system in the form of matrix of adjacent measurement position differences, the error value composed of the polynomial coefficients of geometric error and perpendicularity error is obtained , and obtain the geometric error and verticality error.

4. The error identification method of a three-dimensional coordinate measuring machine according to claim 3, characterized in that: The geometric error is a cubic polynomial, so that the error value composed of the polynomial coefficient of the geometric error and the verticality error is It includes 54 polynomial coefficients of 18 geometric errors and 3 constant verticality errors, totaling 57 parameters to be solved.

5. The error identification method of a three-dimensional coordinate measuring machine according to claim 1, characterized in that: After step S3, the obtained geometric error and verticality error are substituted into the error equation to obtain the right side of the error equation. , combined with the radius of the standard sphere Get the impact of probe error ; Impact on probe errors The probe error distribution in continuous space is obtained through surface fitting or neural network modeling learning.

6. The error identification method of a three-dimensional coordinate measuring machine according to claim 1, characterized in that: The standard ball is a standard ball with a nanometer-level sphericity error level. The standard ball is made of microcrystalline glass material, and the preparation of the standard ball includes: polishing the standard ball made of microcrystalline glass material, and then measuring the nanometer-level sphericity error of the standard ball by laser wavefront interferometer. If the nanometer-level sphericity error does not meet the requirements, continue to polish the standard ball made of microcrystalline glass material until the nanometer-level sphericity error meets the requirements.

7. A coordinate measuring machine error identification system, comprising a microprocessor and a memory connected to each other, characterized in that: The microprocessor is programmed or configured to execute the coordinate measuring machine error identification method according to any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program or instruction stored therein, characterized in that: The computer program or instruction is programmed or configured to execute the coordinate measuring machine error identification method according to any one of claims 1 to 6 through a processor.

9. A computer program product comprising a computer program or instructions, characterized in that The computer program or instruction is programmed or configured to execute the coordinate measuring machine error identification method according to any one of claims 1 to 6 through a processor.

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