Method and device for compensating measurement basis thermal deformation of large assembly fixture

Abstract

The invention relates to the technical field of digital assembly of parts, and discloses a large-scale assembly fixture measurement reference thermal deformation compensation method and device, and the method comprises the steps: obtaining a real-time temperature when a laser tracker measures a coordinate value of a common observation point through a temperature sensor, constructing a temperature field, and carrying out the measurement of the coordinate value through a temperature sensor; then calculating the thermal deformation displacement of each common observation point through a finite element method, compensating the theoretical coordinate point set, registering the compensated and corrected theoretical coordinate point set with the measurement coordinate point set, solving a least square function about the sum of squares of distance errors by adopting a singular value decomposition method, and calculating the thermal deformation displacement of each common observation point; the rotation matrix and the translation vector when the point set in the measurement coordinate system is transferred to the unified coordinate system are obtained, and the station transfer coordinate value is obtained, so that the station transfer precision of the laser tracker is improved, and the method has the outstanding advantage of carrying out rapid compensation aiming at the temperature influence.

Description

Technical Field

[0001] This invention relates to the field of digital assembly technology for parts and components, and discloses a method and device for compensating for thermal deformation of a large assembly jig measurement reference. Background Technology

[0002] Laser trackers, as large-size, high-precision measuring instruments, are widely used in the field of digital assembly measurement of large components. When measuring large equipment or in complex measurement environments, if a single laser tracker cannot cover all the points to be measured at a single location, two methods are required: one is to use a single laser tracker to perform time-division measurement at multiple different locations, and the other is to use multiple laser trackers to perform measurement simultaneously at a fixed location. Both methods involve unifying different measurement data into a common coordinate system for subsequent processing and analysis; this process is called relocation. The purpose of relocation is to expand the measurement range of the laser tracker, enabling it to accurately measure large, complex-shaped, or difficult-to-measure objects or spaces in a single operation. Essentially, relocation involves matching the point sets of two coordinate systems, i.e., point group registration; these points are usually called common observation (ERS) points.

[0003] The accuracy of transfer stations directly determines the accuracy and quality of aircraft assembly. Many factors influence the accuracy of laser trackers during transfer, but with improvements in laser tracker accuracy management, the introduction of new matching algorithms, and the continuous enhancement of user skills, measurement stability and accuracy are constantly improving. Engineering surveying practice shows that temperature variation is the most significant factor affecting transfer station accuracy. During the transfer of coordinate point sets from a measurement coordinate system to a unified coordinate system, thermal deformation of the jig due to temperature changes can cause displacement of common observation points on the jig. If the theoretical coordinate values ​​from calibration are still used for point set registration, a large transfer station thermal deformation error will be introduced, reducing the transfer station accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a method and device for compensating for thermal deformation of a large assembly frame measurement reference, which can improve the switching accuracy of the laser tracker and has the outstanding advantage of rapid compensation for temperature effects.

[0005] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows: A method for compensating for thermal deformation of a large assembly jig measurement reference includes: Establish a spatial rectangular coordinate system O-XYZ, arrange the first and second stations of the laser tracker on the outer perimeter of the cubic frame, and fix at least three non-collinear common observation points on the frame that makes up the cubic frame; A detection rod is set inside the cubic frame. The detection rod is formed by the orthogonal intersection of three rods of the same material as the frame. Two reflective targets are set at intervals along the length of the corresponding rod on each rod. Temperature sensors are arranged at the eight vertices of the cubic frame to collect temperature data of the measurement space in which the cubic frame is located. Under the preset calibration temperature, a laser tracker is used to measure the first measurement coordinates of each common observation point in O-XYZ at the first station, as well as to detect the first coordinates of the reflective targets of each rod on the benchmark, and analyze to obtain the first length measurement value between the two reflective targets on each rod. A laser tracker is used to measure the second coordinate values ​​of each common observation point at the second station, as well as the second coordinates of the reflective targets of each pole on the benchmark. The second length measurement value between the two reflective targets on each pole is obtained by analysis, and the real-time temperature data of eight temperature sensors at the current moment is recorded. The three-dimensional temperature field of the measurement space is constructed by interpolation. Based on the thermal expansion coefficient of the frame material of the cubic frame, the preset calibration temperature, and the temperature at the two reflective targets of each member in the three-dimensional temperature field, the thermal deformation of each member of the test benchmark is analyzed and obtained; and based on the first length measurement value, the second length measurement value, and the corresponding thermal deformation of each member, the compensation deviation between the first length measurement value and the second length measurement value is analyzed and obtained. If the compensation deviation is not greater than the preset deviation threshold, the finite element method is used to analyze and obtain the thermal deformation of each common observation point along the three coordinate axes under the condition of the change between the corresponding temperature in the three-dimensional temperature field and the temperature when the second station is measured. The thermal deformation is then used to compensate each first measurement coordinate value to obtain the compensated coordinates of each common observation point. A least squares function of the sum of squared distance errors for the common observation points is constructed, and the rotation matrix and translation vector that satisfy the least squares function value are solved by the singular value decomposition method. The rotation matrix and translation vector are then used to correct the second measurement coordinate value to obtain the corrected coordinate value after the station transfer.

[0006] Furthermore, the compensation deviation between the first length measurement and the second length measurement on each member ,in For the first The second length measurement between two reflective targets on a single rod; whereby... For the first testing benchmark Thermal deformation of each member , The coefficient of thermal expansion of the frame material of the cubic frame is given. For the first The first length measurement between the two reflective targets on the rod. , For the third temperature field in the three-dimensional temperature field The temperature at one of the reflective targets on the rod. For the third temperature field in the three-dimensional temperature field The temperature at another reflective target on one of the rods This is the preset calibration temperature.

[0007] Furthermore, the preset deviation threshold is determined according to the accuracy requirements, and the value range is -0.1mm to +0.1mm.

[0008] Furthermore, the compensated coordinates of each common observation point are: ,in For the first The first measured coordinates of the common observation points , The number of public observation points, For the first Under the condition that the temperature at each common observation point changes between the temperature at the corresponding temperature in the three-dimensional temperature field and the temperature measured at the second station, the... Thermal deformation along three coordinate axes at a common observation point.

[0009] Furthermore, the least squares function of the constructed common observation points with respect to the sum of squared distance errors is: ,in Let be a rotation matrix. The translation vector is used; the coordinates after the relocation are... , For the first The second measured coordinate value of the common observation point.

[0010] To achieve the above-mentioned technical effects, the present invention also provides a large assembly jig measurement reference thermal deformation compensation device, used to implement the aforementioned large assembly jig measurement reference thermal deformation compensation method, comprising: An array of observation points, comprising at least three non-collinear common observation points set on the frame of a cubic frame; A laser tracker is used to acquire all observation points on the observation point array on the assembly jig under test from at least two stations; The testing benchmark is set inside the cubic frame; Temperature sensors are used to collect temperature data at the eight vertices of the cubic frame; The temperature field construction module is used to construct a three-dimensional temperature field of the measurement space based on the collected temperature data of the measurement space where the cubic frame is located, using an interpolation method. The first analysis module is used to analyze and obtain the first and second length measurements between the two reflective targets on each rod. The compensation deviation analysis module is used to analyze and obtain the thermal deformation of each member of the test bar based on the thermal expansion coefficient of the frame material of the cubic frame, the preset calibration temperature, and the temperature at the two reflective targets of each member in the three-dimensional temperature field; and to analyze and obtain the compensation deviation between the first length measurement value and the second length measurement value based on the first length measurement value, the second length measurement value and the corresponding thermal deformation of each member. The first measurement coordinate compensation module is used to analyze and obtain the thermal deformation of each common observation point along the three coordinate axes under the condition that the temperature of each common observation point in the three-dimensional temperature field changes from the temperature measured at the second station when the compensation deviation is not greater than the preset deviation threshold. The module then compensates each first measurement coordinate value according to the thermal deformation to obtain the compensated coordinates of each common observation point. The relocation coordinate correction module is used to construct the least squares function of the sum of squared distance errors of the common observation points, and to solve the rotation matrix and translation vector that satisfy the least squares function value using the singular value decomposition method. The rotation matrix and translation vector are then used to correct the second measurement coordinate value to obtain the corrected coordinate value after the relocation.

[0011] Furthermore, in the compensation deviation analysis module, the compensation deviation between the first length measurement value and the second length measurement value on each member is... ,in For the first The second length measurement between two reflective targets on a single rod; whereby... For the first testing benchmark Thermal deformation of each member , The coefficient of thermal expansion of the frame material of the cubic frame is given. For the first The first length measurement between the two reflective targets on the rod. , For the third temperature field in the three-dimensional temperature field The temperature at one of the reflective targets on the rod. For the third temperature field in the three-dimensional temperature field The temperature at another reflective target on one of the rods This is the preset calibration temperature.

[0012] Furthermore, in the first measurement coordinate compensation module, the compensated coordinates of each common observation point are: ,in For the first The first measured coordinates of the common observation points , The number of public observation points, For the first Under the condition that the temperature at each common observation point changes between the temperature at the corresponding temperature in the three-dimensional temperature field and the temperature measured at the second station, the... Thermal deformation along three coordinate axes at a common observation point.

[0013] Furthermore, in the transfer station coordinate correction module, the least squares function of the constructed common observation point with respect to the sum of squared distance errors is: ,in Let be a rotation matrix. The translation vector is used; the coordinates after the relocation are... , For the first The second measured coordinate value of the common observation point.

[0014] Compared with the prior art, the beneficial effects of this invention are as follows: This invention obtains the real-time temperature when the laser tracker measures the coordinates of the common observation points using a temperature sensor, constructs a temperature field, calculates the thermal deformation displacement of each common observation point using the finite element method, compensates for the theoretical coordinate point set, registers the compensated theoretical coordinate point set with the measured coordinate point set, and uses the singular value decomposition method to solve the least squares function for the sum of squared distance errors, obtaining the rotation matrix and translation vector for transferring the point set from the measured coordinate system to the unified coordinate system, thus obtaining the transfer coordinate values. This improves the transfer accuracy of the laser tracker and has the outstanding advantage of rapid compensation for temperature effects. Attached Figure Description

[0015] Figure 1 This is a flowchart of the thermal deformation compensation method for measuring the reference of a large assembly frame in the embodiment; Figure 2 This is a structural block diagram of the thermal deformation compensation device for measuring the large assembly frame in the embodiment; Figure 3 This is a schematic diagram of the thermal deformation compensation device for measuring the large assembly frame in the embodiment. Figure 4 This is a schematic diagram of the detection benchmark structure in the embodiment; The components include: 1. Cubic frame; 2. Laser tracker; 3. Common observation point; 4. Detection benchmark; 5. Reflection target; 6. Temperature sensor; 7. Temperature field construction module; 8. First analysis module; 9. Compensation deviation analysis module; 10. First measurement coordinate compensation module; and 11. Transfer station coordinate correction module. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0017] Example 1 See Figures 1 to 4 A method for compensating for thermal deformation of a large assembly jig measurement reference, comprising: Establish a spatial rectangular coordinate system O-XYZ, arrange the first and second stations of the laser tracker 2 on the outer periphery of the cubic frame 1, and fix at least three non-collinear common observation points 3 on the frame that makes up the cubic frame 1. A detection rod 4 is set inside the cubic frame 1. The detection rod 4 is formed by the orthogonal intersection of three rods of the same material as the frame. Two reflective targets 5 are set at intervals along the length of the corresponding rod on each rod. Temperature sensors 6 are arranged at the eight vertices of the cubic frame 1 to collect temperature data of the measurement space in which the cubic frame 1 is located. At a preset calibration temperature, the laser tracker 2 is used to measure the first measurement coordinates of each common observation point 3 in O-XYZ at the first station, as well as the first coordinates of the reflective target 5 of each rod on the benchmark 4, and the first length measurement value between the two reflective targets 5 on each rod is obtained by analysis. The laser tracker 2 is used to measure the second measurement coordinates of each common observation point 3 at the second station, and to detect the second coordinates of the reflective targets 5 of each rod on the benchmark 4. The second length measurement value between the two reflective targets 5 on each rod is obtained by analysis, and the real-time temperature data of the eight temperature sensors 6 at the current moment is recorded. The three-dimensional temperature field of the measurement space is constructed by interpolation. Based on the thermal expansion coefficient of the frame material of the cubic frame 1, the preset calibration temperature, and the temperature of the two reflective targets 5 of each member in the three-dimensional temperature field, the thermal deformation of each member of the test bar 4 is analyzed and obtained; and based on the first length measurement value, the second length measurement value, and the corresponding thermal deformation of each member, the compensation deviation between the first length measurement value and the second length measurement value is analyzed and obtained. If the compensation deviation is not greater than the preset deviation threshold, the finite element method is used to analyze and obtain the thermal deformation of each common observation point 3 along the three coordinate axes under the condition of the change between the corresponding temperature in the three-dimensional temperature field and the temperature when the second station is measured. The thermal deformation is then used to compensate each first measurement coordinate value to obtain the compensated coordinates of each common observation point 3. Construct the least squares function of the sum of squared distance errors for common observation point 3, and use the singular value decomposition method to solve for the rotation matrix and translation vector that satisfy the least squares function value. Use the rotation matrix and translation vector to correct the second measurement coordinate value to obtain the corrected coordinate value after the station transfer.

[0018] In this embodiment, the real-time temperature of the laser tracker 2 when measuring the coordinates of the common observation point 3 is obtained by the temperature sensor 6, and a temperature field is constructed. Then, the thermal deformation displacement of each common observation point 3 is calculated by the finite element method, and the theoretical coordinate point set is compensated. The compensated and corrected theoretical coordinate point set is registered with the measured coordinate point set. The singular value decomposition method is used to solve the least squares function of the sum of squares of distance error, and the rotation matrix and translation vector for transferring the point set from the measured coordinate system to the unified coordinate system are obtained. The transfer coordinate values ​​are obtained, thereby improving the transfer accuracy of the laser tracker 2 and having the outstanding advantage of rapid compensation for temperature effects.

[0019] Based on the same inventive concept, this embodiment also provides a large assembly jig measurement reference thermal deformation compensation device for implementing the aforementioned large assembly jig measurement reference thermal deformation compensation method, including: An array of observation points, comprising at least three non-collinear common observation points 3 set on the frame of a cubic frame 1; Laser tracker 2 is used to acquire all observation points on the observation point array on the assembly frame under test from at least two stations; The testing benchmark 4 is set inside the cubic frame 1; Temperature sensor 6 is used to collect temperature data at the eight vertices of the cubic frame 1; Temperature field construction module 7 is used to construct a three-dimensional temperature field of the measurement space based on the collected temperature data of the measurement space where the cubic frame 1 is located, using an interpolation method. The first analysis module 8 is used to analyze and obtain the first and second length measurements between the two reflective targets 5 on each rod. The compensation deviation analysis module 9 is used to analyze and obtain the thermal deformation of each member of the test bar 4 based on the thermal expansion coefficient of the frame material of the cubic frame 1, the preset calibration temperature, and the temperature of the two reflective targets 5 of each member in the three-dimensional temperature field; and to analyze and obtain the compensation deviation between the first length measurement value and the second length measurement value based on the first length measurement value, the second length measurement value and the corresponding thermal deformation of each member. The first measurement coordinate compensation module 10 is used to analyze and obtain the thermal deformation of each common observation point 3 along the three coordinate axes under the condition of the change between the corresponding temperature in the three-dimensional temperature field and the temperature when the second station measurement, when the compensation deviation is not greater than the preset deviation threshold, and to compensate each first measurement coordinate value according to the thermal deformation to obtain the compensated coordinates of each common observation point 3. The relocation coordinate correction module 11 is used to construct the least squares function of the common observation point 3 with respect to the sum of squared distance errors, and to use the singular value decomposition method to solve for the rotation matrix and translation vector that satisfy the least squares function value. The rotation matrix and translation vector are then used to correct the second measurement coordinate value to obtain the corrected coordinate value after the relocation.

[0020] Example 2 See Figure 1 , Figure 3 and Figure 4 A method for compensating for thermal deformation of a large assembly jig measurement reference, comprising: Step 1: Establish a spatial rectangular coordinate system O-XYZ. Arrange the first and second stations of the laser tracker 2 on the outer perimeter of the cubic frame 1. Fix at least three non-collinear common observation points 3 on the frame that makes up the cubic frame 1. In this embodiment, the required transfer stations are predetermined. There are 3 public observation points, among which Furthermore, all common observation points 3 are not collinear, ensuring that the laser tracker 2 can measure each common observation point 3 at both the first station A and the second station B.

[0021] Step 2: Set up a detection rod 4 inside the cubic frame 1. The detection rod 4 is formed by three rods of the same material as the frame intersecting at an orthogonal angle. Two reflective targets 5 are set at intervals along the length of each rod. Temperature sensors 6 are arranged at the eight vertices of the cubic frame 1 to collect temperature data of the measurement space in which the cubic frame 1 is located.

[0022] Step 3: Under the preset calibration temperature, use laser tracker 2 to measure the first measurement coordinates of each common observation point 3 in O-XYZ at the first station A, and detect the first coordinates of the reflective target 5 of each rod on the rod 4, and analyze to obtain the first length measurement value between the two reflective targets 5 on each rod. In this embodiment, at a certain calibration temperature Next, place the laser tracker 2 at the first station A and measure the theoretical coordinate values ​​of each common observation point 3. , , The number of public observation points 3 was obtained in total. Theoretical coordinate values Simultaneously, the first coordinates of the reflective target 5 of each member on the test pole 4 are measured, and the theoretical length of each member is calculated using the Euclidean distance formula. , .

[0023] Step 4: Use laser tracker 2 to measure the second measurement coordinates of each common observation point 3 at the second station B, and detect the second coordinates of the reflective targets 5 of each rod on the marker 4. Analyze and obtain the second length measurement value between the two reflective targets 5 on each rod, and record the real-time temperature data of the eight temperature sensors 6 at the current moment. Construct the three-dimensional temperature field of the measurement space by interpolation. In this embodiment, the laser tracker 2 is moved to the second station B to measure the coordinate values ​​of each common observation point 3. Simultaneously, the coordinates of the two reflective targets 5 of each rod of the test rod 4 are measured, and the theoretical length of each rod is calculated according to the Euclidean distance formula. It also records the real-time temperature data from the eight temperature sensors 6 at the current moment. A three-dimensional temperature field was constructed using trilinear interpolation.

[0024] Step 5: Based on the thermal expansion coefficient of the frame material of the cubic frame 1, the preset calibration temperature, and the temperature of the two reflective targets 5 of each rod in the three-dimensional temperature field, analyze and obtain the thermal deformation of each rod of the test rod 4; and based on the first length measurement value, the second length measurement value, and the corresponding thermal deformation of each rod, analyze and obtain the compensation deviation between the first length measurement value and the second length measurement value. In this embodiment, the compensation deviation between the first length measurement value and the second length measurement value on each member is addressed. ,in For the first The second length measurement value between the two reflective targets 5 on the rod; whereby For testing the fourth benchmark Thermal deformation of each member , The coefficient of thermal expansion of the frame material of cubic frame 1 is given. For the first The first length measurement value between the two reflective targets 5 on the rod. , For the third temperature field in the three-dimensional temperature field The temperature at one of the reflective targets on the rod. For the third temperature field in the three-dimensional temperature field The temperature at point 5 on another reflective target on the rod. This is the preset calibration temperature.

[0025] Step 6: Determine whether the compensation deviation is less than or equal to the preset deviation threshold. If so, use the finite element method to analyze and obtain the thermal deformation of each common observation point 3 along the three coordinate axes under the condition of the change between the corresponding temperature in the three-dimensional temperature field and the temperature when the second station is measured. Then, compensate each first measurement coordinate value according to the thermal deformation to obtain the compensated coordinates of each common observation point 3. The preset deviation threshold is determined according to the accuracy requirements, and its value ranges from -0.1mm to +0.1mm. In this embodiment, the preset deviation threshold is 0.1mm. For cubic frames 1 with other structures or materials, the corresponding preset deviation threshold values ​​are determined according to the design requirements. If there are Then, the finite element method is used to analyze and obtain the thermal deformation of each common observation point 3 along the three coordinate axes under the condition that the temperature of each common observation point 3 changes from the temperature measured at the second station in the three-dimensional temperature field. The thermal deformation amount is used to compensate for each first measured coordinate value, resulting in the compensated coordinates of each common observation point 3. Otherwise, the compensation will fail, and you will have to return to step four to remeasure until... .

[0026] Step 7: Construct the least squares function of the sum of squared distance errors for common observation point 3, and use the singular value decomposition method to solve for the rotation matrix and translation vector that satisfy the least squares function value. Use the rotation matrix and translation vector to correct the second measurement coordinate value to obtain the corrected coordinate value after the station transfer. In this embodiment, the least squares function of the constructed common observation point 3 with respect to the sum of squared distance errors is: ,in Let be a rotation matrix. The translation vector is used; the coordinates after the relocation are... , For the first The second measured coordinate value of the three common observation points.

[0027] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for compensating for thermal deformation of a large assembly jig measurement reference, characterized in that, include: Establish a spatial rectangular coordinate system O-XYZ, arrange the first and second stations of the laser tracker on the outer perimeter of the cubic frame, and fix at least three non-collinear common observation points on the frame that makes up the cubic frame; A detection rod is set inside the cubic frame. The detection rod is formed by the orthogonal intersection of three rods of the same material as the frame. Two reflective targets are set at intervals along the length of the corresponding rod on each rod. Temperature sensors are arranged at the eight vertices of the cubic frame to collect temperature data of the measurement space in which the cubic frame is located. Under the preset calibration temperature, a laser tracker is used to measure the first measurement coordinates of each common observation point in O-XYZ at the first station, as well as to detect the first coordinates of the reflective targets of each rod on the benchmark, and analyze to obtain the first length measurement value between the two reflective targets on each rod. A laser tracker is used to measure the second coordinate values ​​of each common observation point at the second station, as well as the second coordinates of the reflective targets of each pole on the benchmark. The second length measurement value between the two reflective targets on each pole is obtained by analysis, and the real-time temperature data of eight temperature sensors at the current moment is recorded. The three-dimensional temperature field of the measurement space is constructed by interpolation. Based on the thermal expansion coefficient of the cubic frame material, the preset calibration temperature, and the temperature at the two reflective targets of each member in the three-dimensional temperature field, the thermal deformation of each member of the test benchmark is analyzed and obtained. Based on the first length measurement value, the second length measurement value, and the corresponding thermal deformation of each member, the compensation deviation between the first length measurement value and the second length measurement value is analyzed and obtained. If the compensation deviation is not greater than the preset deviation threshold, the finite element method is used to analyze and obtain the thermal deformation of each common observation point along the three coordinate axes under the condition of the change between the corresponding temperature in the three-dimensional temperature field and the temperature when the second station is measured. The thermal deformation is then used to compensate each first measurement coordinate value to obtain the compensated coordinates of each common observation point. A least squares function of the sum of squared distance errors for the common observation points is constructed, and the rotation matrix and translation vector that satisfy the least squares function value are solved by the singular value decomposition method. The rotation matrix and translation vector are then used to correct the second measurement coordinate value to obtain the corrected coordinate value after the station transfer.

2. The method for compensating for thermal deformation of a large assembly jig measurement reference according to claim 1, characterized in that, Compensation deviation between the first and second length measurements on each member ,in For the first The second length measurement between two reflective targets on a single rod; whereby... For the first testing benchmark Thermal deformation of each member , The coefficient of thermal expansion of the frame material of the cubic frame is given. For the first The first length measurement between the two reflective targets on the rod. , For the third temperature field in the three-dimensional temperature field The temperature at one of the reflective targets on the rod. For the third temperature field in the three-dimensional temperature field The temperature at another reflective target on one of the rods This is the preset calibration temperature.

3. The method for compensating for thermal deformation of a large assembly jig measurement reference according to claim 1, characterized in that, The preset deviation threshold is determined according to the accuracy requirements, and the value range is -0.1mm to +0.1mm.

4. The method for compensating for thermal deformation of a large assembly jig measurement reference according to claim 1, characterized in that, The compensated coordinates of each common observation point are: ,in For the first The first measured coordinates of the common observation points , The number of public observation points, For the first Under the condition that the temperature at each common observation point changes between the temperature at the corresponding temperature in the three-dimensional temperature field and the temperature measured at the second station, the... Thermal deformation along three coordinate axes at a common observation point.

5. The method for compensating for thermal deformation of a large assembly jig measurement reference according to claim 4, characterized in that, The least squares function of the common observation points with respect to the sum of squared distance errors is: ,in Let be a rotation matrix. The translation vector is used; the coordinates after the relocation are... , For the first The second measured coordinate value of the common observation point.

6. A thermal deformation compensation device for a large assembly jig measuring reference, used to implement the thermal deformation compensation method for a large assembly jig measuring reference as described in any one of claims 1-5, characterized in that, include: An array of observation points, comprising at least three non-collinear common observation points set on the frame of a cubic frame; A laser tracker is used to acquire all observation points on the observation point array on the assembly jig under test from at least two stations; The testing benchmark is set inside the cubic frame; Temperature sensors are used to collect temperature data at the eight vertices of the cubic frame; The temperature field construction module is used to construct a three-dimensional temperature field of the measurement space based on the collected temperature data of the measurement space where the cubic frame is located, using an interpolation method. The first analysis module is used to analyze and obtain the first and second length measurements between the two reflective targets on each rod. The compensation deviation analysis module is used to analyze and obtain the thermal deformation of each member of the test benchmark based on the thermal expansion coefficient of the frame material of the cubic frame, the preset calibration temperature, and the temperature at the two reflective targets of each member in the three-dimensional temperature field. Based on the first length measurement value, the second length measurement value, and the corresponding thermal deformation of each member, the compensation deviation between the first length measurement value and the second length measurement value is analyzed and obtained. The first measurement coordinate compensation module is used to analyze and obtain the thermal deformation of each common observation point along the three coordinate axes under the condition that the temperature of each common observation point in the three-dimensional temperature field changes from the temperature measured at the second station when the compensation deviation is not greater than the preset deviation threshold. The module then compensates each first measurement coordinate value according to the thermal deformation to obtain the compensated coordinates of each common observation point. The relocation coordinate correction module is used to construct the least squares function of the sum of squared distance errors of the common observation points, and to solve the rotation matrix and translation vector that satisfy the least squares function value using the singular value decomposition method. The rotation matrix and translation vector are then used to correct the second measurement coordinate value to obtain the corrected coordinate value after the relocation.

7. The large assembly jig measurement reference thermal deformation compensation device according to claim 6, characterized in that, In the compensation deviation analysis module, the compensation deviation between the first length measurement value and the second length measurement value on each member is calculated. ,in For the first The second length measurement between two reflective targets on a single rod; whereby... For the first testing benchmark Thermal deformation of each member , The coefficient of thermal expansion of the frame material of the cubic frame is given. For the first The first length measurement between the two reflective targets on the rod. , For the third temperature field in the three-dimensional temperature field The temperature at one of the reflective targets on the rod. For the third temperature field in the three-dimensional temperature field The temperature at another reflective target on one of the rods This is the preset calibration temperature.

8. The large assembly jig measuring reference thermal deformation compensation device according to claim 6, characterized in that, In the first measurement coordinate compensation module, the compensated coordinates of each common observation point are: ,in For the first The first measured coordinates of the common observation points , The number of public observation points, For the first Under the condition that the temperature at each common observation point changes between the temperature at the corresponding temperature in the three-dimensional temperature field and the temperature measured at the second station, the... Thermal deformation along three coordinate axes at a common observation point.

9. The large assembly frame measurement reference thermal deformation compensation device according to claim 8, characterized in that, In the transfer station coordinate correction module, the least squares function of the common observation point with respect to the sum of squared distance errors is: ,in Let be a rotation matrix. The translation vector is used; the coordinates after the relocation are... , For the first The second measured coordinate value of the common observation point.

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