Complex scene-oriented global measurement field construction method

Abstract

The invention relates to a global measurement field construction method for a complex scene, and the method comprises the steps: fixedly arranging a plurality of target seats which are suitable for the placement of laser reflection target balls of a laser tracker in the scene, and enabling the target seats to serve as visual reference points; laying a laser tracker station; measuring three-dimensional coordinate values of the laser tracker stations and the visual reference point and laser interference ranging values of the laser tracker stations and the visual reference point, and obtaining measurement data of the visual reference point under different laser tracker stations; the method comprises the following steps: constructing a spatial transformation relationship among station coordinate systems of laser trackers, converting measurement data of the laser trackers to a global coordinate system, and constructing a global measurement field; and carrying out adjustment optimization on the obtained global measurement field. According to the method provided by the invention, high-precision measurement field construction oriented to large-size complex-structure parts is realized, the precision and robustness of coordinate calculation are improved, and the problem that traditional measurement field construction in a complex scene is easy to block is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft assembly, and in particular to a global measurement field construction method for complex scenes. Background Art

[0002] Aircraft digital assembly technology is a key enabler for the rapid development of the modern aircraft manufacturing industry. To achieve collaborative operation among various digital devices, various types of tooling, and measuring instruments, a unified measurement benchmark covering the entire assembly site is necessary. The aircraft assembly global measurement field is a global 3D measurement network that integrates multiple types of digital measuring equipment, positioning systems, and reference benchmarks. It is designed to address the requirements of large-scale, multi-coordinate system, and high-precision collaborative measurement during the aviation assembly process. Establishing a high-precision global measurement field is crucial.

[0003] Constructing a global measurement field based on laser multilateration is a common method for constructing assembly measurement fields. This method uses four or more laser trackers to measure reference points and builds a network structure based on high-precision interferometric distance measurements. However, its use presupposes that the laser trackers have line of sight to all reference points. However, with the advancement of aviation assembly technology, current measurement scenarios are more complex, such as large, complex spatial structures and environments with multiple obstacles. Frequent movement of tracker stations is required for complex structures, and the lack of a systematic station planning method can easily lead to measurement blind spots and repeated measurements, resulting in inefficient measurement field construction. Given the large size and complex environment of the measurement field, it is difficult to ensure the uniformity and accuracy of local data to the global measurement field, and the accuracy of coordinate conversion between measurement stations is difficult to guarantee. In scenarios with obstructions or light reflections, line of sight cannot be guaranteed, resulting in data loss or deviation, making traditional laser multilateration measurement field construction unsuitable. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for constructing a global measurement field for complex scenarios. This method addresses the challenges of traditional methods in complex scenarios, such as the frequent movement of tracker stations, low measurement field construction efficiency, difficulty ensuring data consistency and station coordinate conversion accuracy, and a lack of resilience to interference within the scene. Based on regional division and multi-station transfer optimization, combined with high-precision laser interferometry ranging values, this method achieves high-precision construction of a global measurement field, resolving the difficulty of constructing a global measurement field in complex scenarios.

[0005] To solve the above technical problems, the present invention provides the following technical solution: a method for constructing a global measurement field for complex scenes, comprising the following steps:

[0006] S1. Based on the measurement space range, multiple target mounts suitable for placing laser tracker laser reflective target balls are fixedly arranged in the scene to serve as visual reference points of the measurement field;

[0007] S2. Divide the measurement area according to the structure of the measurement object and arrange the laser tracker station in each measurement area;

[0008] S3, sequentially measuring the three-dimensional coordinate values ​​and laser interferometric ranging values ​​of the visual reference points at different laser tracker positions;

[0009] S4. Based on the three-dimensional coordinates of the visual reference points at different laser tracker positions, a coordinate conversion model is constructed between the coordinate systems of adjacent laser tracker positions. The coordinate information of the common visual reference points is used to solve the optimized conversion parameters between the adjacent laser tracker positions, and the spatial transformation relationship is obtained to construct a global coordinate system. According to the spatial transformation relationship, the coordinates of each laser tracker position and the visual reference point are converted to the global coordinate system to obtain the corresponding global coordinates, and a global measurement field is constructed.

[0010] S5, the global measurement field obtained to step S4 is carried out adjustment optimization, with the laser tracker position global coordinates and the visual reference point global coordinates of this measurement field for optimizing initial value, build measurement field optimization model by laser polygon method, utilize the laser tracker position to the laser interferometry ranging value of visual reference point to solve the optimization correction value of the two coordinates.

[0011] Furthermore, in step S1, the specific process includes: the target seats of the laser tracker laser reflection target ball should be evenly arranged in the measurement space, the positions of any three adjacent target seats cannot be on the same straight line, and the target seats are randomly arranged to ensure that the distances between the target seats are not the same.

[0012] Furthermore, in step S2, the specific process includes: for the layout of the laser tracker stations, it is required that there are laser tracker stations in different measurement areas and the measurement light of the visible reference points in adjacent measurement areas is not blocked.

[0013] Furthermore, in step S2, there must be at least three common visual reference points between adjacent laser tracker stations. Similarly, there must be at least three common visual reference points between the last laser tracker station and the first laser tracker station.

[0014] Furthermore, in step S3, the specific process includes: placing the laser reflective target ball of the laser tracker on the target base, measuring the three-dimensional coordinate value and laser interference ranging value of the visible reference point under the laser tracker station, moving the laser tracker station in sequence, and obtaining the measurement data of the visible reference point under different laser tracker stations.

[0015] Furthermore, in step S4, the specific process includes the following steps:

[0016] S41. The three-dimensional coordinates of the visual reference point obtained by measuring the j-th laser tracker station are marked as P j The three-dimensional coordinates of the same visual reference point measured by the j+1th laser tracker station are marked as P j+1 , construct the coordinate transformation model between adjacent laser tracker stations:

[0017] P j+1 =R j P j +t j ,j=1,2,…,n

[0018] Among them, R j is the rotation parameter, t j is the translation parameter;

[0019] S42, using the least squares algorithm to solve the conversion parameters between adjacent laser tracker stations, that is, the rotation parameter R j and the translation parameter t j ;

[0020] S43. The visual reference point set P1 of the first laser tracker station is transferred through each laser station in sequence according to the conversion parameters, and finally returned to the first laser tracker station in a closed loop to obtain the visual reference point set P′1. In the ideal error-free case, the visual reference point set P1 should be completely equal to P′1. The total number of laser tracker stations is defined as n, and the synthetic rotation is defined as Define the synthetic translation as where R n and t n is the rotation parameter and translation parameter between the n-1th station and the nth station. According to the above closed-loop consistency condition, the calculation expression R is obtained. C P1+t C =P1;

[0021] S44. Establish the rotation constraint equation R C =I, and translation constraint equation t C =0, where I is a 3×3 identity matrix. The two constraint equations are linearized to obtain the overall constraint equation:

[0022]

[0023] in, To optimize the conversion parameters, that is, the correction value vector of the conversion parameters, C is the coefficient matrix, and W is the constant term matrix;

[0024] S45. Based on the indirect adjustment model with parameters and the overall constraint equation in step S44, introduce the Lagrangian multiplier vector K, and construct the Lagrangian function:

[0025]

[0026] Wherein, V is the coordinate correction vector corresponding to the public visual reference point after the coordinate system is converted. In the indirect adjustment model, B is the error equation coefficient matrix, l is the deviation between the coordinates of the public visual reference point after the coordinate conversion model and the measured coordinates, and P is the measurement weight matrix, which is the unit matrix under equal precision measurement.

[0027] S46, find the partial derivative of the Lagrangian function Φ constructed in step S45 and set it to zero, and solve to obtain the optimized conversion parameter The expression:

[0028]

[0029] S47, taking the first laser tracker station coordinate system as the global coordinate system, and optimizing the conversion parameters solved in step S46 Combined with the coordinate transformation model constructed in step S41, the spatial transformation relationship between the coordinate systems of adjacent laser tracker stations is obtained. The stations are rotated in sequence to obtain the transformation relationship between the coordinate system of each laser tracker station and the global coordinate system. The translation parameters of each laser tracker station coordinate system to the global coordinate system are the global coordinates of each laser tracker station. At the same time, the measurement data of each laser tracker is converted to the global coordinate system through this transformation relationship to obtain the global coordinates of the visible reference points at each laser tracker station, thereby achieving data unification and constructing a global measurement field.

[0030] Furthermore, in step S5, the specific process includes the following steps:

[0031] S51. Based on the global coordinates of all laser tracker positions and corresponding visual reference points obtained in step S4, and the laser interferometry ranging value obtained by the laser tracker, a measurement equation is established according to the distance formula between two points. The equation is expressed as:

[0032]

[0033] Among them, l ij is the laser interferometry distance from the laser tracker to the visual reference point, (x Sj ,y Sj ,z Sj ) is the three-dimensional coordinate of the laser tracker station, (x pj ,y pj ,z pj ) is the three-dimensional coordinate of the visual reference point, ε ij is the measurement error;

[0034] S52, the global coordinates of the laser tracker station and the visual reference point are used as the initial value of optimization, and the global coordinates of the visual reference point are approximately (x Pi (0) ,y Pi (0) ,z Pi (0) ), the global coordinates of the laser tracker station are approximately (x Sj (0) ,y Sj (0) ,z Sj (0) ), using these two approximate values, the approximate laser interferometry distance value is The measurement equation is linearized and expanded at the above approximate value using Taylor's formula to obtain the error equation:

[0035]

[0036] Among them, (δx Sj ,δy Sj ,δz S j) and (δx Pi ,δy Pi ,δz Pi ) is the optimized correction value of the global coordinate approximation of the laser tracker station and the visual reference point, where the coefficients are expressed as follows:

[0037]

[0038] The error equation is expressed as a matrix form: V = A·δX-b; where V is the error vector; A is the coefficient matrix of the error equation, Composition; δX is the global coordinate correction value vector of the laser tracker station and the visual reference point; b is the distance value residual;

[0039] S53, according to the least squares principle formula V T PV=min, and the objective function is obtained:

[0040] (A·δX-b) T P(A·δX-b)=min

[0041] A T PA·δX=A T Pb

[0042] Where P is the laser interferometry distance value l from the laser tracker to the visual reference point ij The weight matrix, if l ij If the measurement is of equal precision, then P takes the unit matrix. ij If the measurement is of unequal precision, then P is determined by l ijThe reciprocal of the square of the measurement uncertainty;

[0043] S54. Use regularized ridge estimation to solve the least squares solution of δX, the equation is:

[0044] δX=(A T A+λI) -1 A T b

[0045] Where I is the identity matrix, and the regularization parameter λ is obtained by the L-curve method. The final solution δX is the optimized correction value of the laser tracker station coordinates and the visual reference point coordinates.

[0046] By means of the above technical solution, the present invention provides a method for constructing a global measurement field for complex scenes, which has at least the following beneficial effects:

[0047] (1) Based on regional division and multi-station transfer optimization, the present invention realizes the preliminary construction of the global measurement field, improves the measurement coverage and measurement efficiency, and provides a basis for the application of laser multilateration;

[0048] (2) The present invention relies on high-precision laser interferometry ranging values ​​to construct an adjustment optimization model, ensures the stability of the solution through the regularized ridge estimation method, effectively improves the accuracy of measurement field construction, and solves the problem that the global measurement field is difficult to construct in complex scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0050] Figure 1 This is a flowchart of an implementation method of a global measurement field construction method for complex scenes according to the present invention. DETAILED DESCRIPTION

[0051] To make the above-mentioned objectives, features, and advantages of the present invention more clearly understood, the present invention is further described below in detail with reference to the accompanying drawings and specific embodiments. This will enable a full understanding of how this application employs technical means to solve technical problems and achieve technical effects, and to implement the invention accordingly.

[0052] Those skilled in the art will appreciate that all or part of the steps in the above-mentioned embodiment methods can be accomplished by instructing the relevant hardware through a program. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0053] Please refer to Figure 1 , shows a specific implementation method of this embodiment. This embodiment realizes the preliminary construction of the global measurement field based on regional division and multi-station transfer optimization, and builds an adjustment optimization model based on high-precision laser interferometry ranging values. The stability of the solution is ensured by the regularized ridge estimation method, which effectively improves the accuracy of measurement field construction and solves the problem that the global measurement field is difficult to construct in complex scenarios.

[0054] Please refer to Figure 1 This embodiment proposes a method for constructing a global measurement field for complex scenes, which includes the following steps:

[0055] S1. Based on the measurement space range, multiple target mounts suitable for placing laser tracker laser reflective target balls are fixedly arranged in the scene to serve as visual reference points of the measurement field;

[0056] As a preferred implementation of step S1, the specific process includes: according to the measurement space range of 10m×10m×2m, an assembly tool of size 5m×5m×2m is placed in the center thereof; 36 1.5-inch magnetic target holders suitable for placing laser target balls of laser trackers are fixed on the outside of the assembly tool and on the ground with hot melt adhesive, and used as visual reference points in the measurement field to ensure the stability of the target holders, avoid the target holders from moving during the placement of the laser target ball, and reduce the uncertainty in the measurement; the target holders of the laser tracker target ball should be evenly distributed in the measurement space, and the target holders should be randomly distributed to ensure that the distances between the target holders are not the same, and the distances between the target holders are approximately 1.5m to 2m; any three adjacent target holders cannot have a "three-point collinearity" situation, that is, the positions of any three adjacent target holders cannot be on the same straight line.

[0057] S2. Divide the measurement area according to the structure of the measurement object and arrange the laser tracker station in each measurement area;

[0058] As a preferred embodiment of step S2, the specific process includes: dividing the measurement field into 8 measurement areas according to the assembly tool structure, deploying a laser tracker station in each measurement area, and deploying the laser tracker station near the assembly tool; the deployment requires that there is a laser tracker station in different measurement areas, and the measurement light of the visible reference points in adjacent areas is not blocked;

[0059] More specifically, there must be at least three common reference points between adjacent laser tracker stations. Similarly, there must be at least three common reference points between the last laser tracker station and the first laser tracker station.

[0060] S3, sequentially measuring the three-dimensional coordinate values ​​and laser interferometric ranging values ​​of the visual reference points at different laser tracker positions;

[0061] As a preferred implementation of step S3, the specific process includes: placing the laser reflective target balls of the laser tracker on the target base respectively, measuring the visible reference points under the laser tracker stations, and obtaining the three-dimensional coordinate values ​​and laser interferometry ranging values ​​of the visible reference points; moving the laser tracker stations in sequence to obtain measurement data at all eight laser tracker stations; in this example, the ranging accuracy of the laser tracker is ±0.5um / m.

[0062] S4. Based on the three-dimensional coordinates of the visual reference points at different laser tracker positions, a coordinate conversion model is constructed between the coordinate systems of adjacent laser tracker positions. The coordinate information of the common visual reference points is used to solve the optimized conversion parameters between the adjacent laser tracker positions, and the spatial transformation relationship is obtained to construct a global coordinate system. According to the spatial transformation relationship, the coordinates of each laser tracker position and the visual reference point are converted to the global coordinate system to obtain the corresponding global coordinates, and a global measurement field is constructed.

[0063] As a preferred implementation of step S4, the specific process includes the following steps:

[0064] S41. The three-dimensional coordinates of the visual reference point obtained by measuring the j-th laser tracker station are marked as P j The three-dimensional coordinates of the same visual reference point measured by the j+1th laser tracker station are marked as P j+1 , construct the coordinate transformation model between adjacent laser tracker stations:

[0065] P j+1 =R j P j +t j ,j=1,2,…,8

[0066] Among them, R j is the rotation parameter, t j is the translation parameter;

[0067] S42. Assume q i and p i For the coordinates of the same common point set in the jth laser tracker station and the j+1th laser tracker station coordinate system, the transformation parameters between the jth laser tracker station coordinate system and the j+1th laser tracker station coordinate system, i.e., the rotation parameter R, are solved in sequence by the least squares algorithm. j and the translation parameter t j , its calculation expression is:

[0068] min||q i -(R j p i +t j )|| 2

[0069] S43, the visual reference point set P1 of the first laser tracker station is converted from the first laser tracker station through laser tracker stations 2, 3, ..., n, and finally closed-looped back to the first laser tracker station to obtain the visual reference point set P ′ 1. In the ideal error-free case, the visual reference point set P1 should be consistent with P ′ 1 is completely equal, the total number of laser tracker stations is defined as n, and the composite rotation is defined as Define the synthetic translation as where R n and t n is the rotation parameter and translation parameter between the n-1th station and the nth station. According to the above closed-loop consistency condition, the calculation expression R is obtained. C P1+t C =P1;

[0070] S44. Establish the rotation constraint equation R C =I, and translation constraint equation t C =0, where I is a 3×3 identity matrix. The two constraint equations are linearized to obtain the overall constraint equation:

[0071]

[0072] in, To optimize the conversion parameters, that is, the correction value vector of the conversion parameters, C is the coefficient matrix, and W is the constant term matrix;

[0073] S45. Based on the indirect adjustment model with parameters and the overall constraint equation in step S44, introduce the Lagrangian multiplier vector K, and construct the Lagrangian function:

[0074]

[0075] Wherein, V is the coordinate correction vector corresponding to the public visual reference point after the coordinate system is converted. In the indirect adjustment model, B is the error equation coefficient matrix, l is the deviation between the coordinates of the public visual reference point after the coordinate conversion model and the measured coordinates, and P is the measurement weight matrix, which is the unit matrix under equal precision measurement.

[0076] S46, find the partial derivative of the Lagrangian function Φ constructed in step S45 and set it to zero, and solve to obtain the optimized conversion parameter The expression:

[0077]

[0078] S47, taking the first laser tracker station coordinate system as the global coordinate system, and optimizing the conversion parameters solved in step S46 Combined with the coordinate transformation model constructed in step S41, the spatial transformation relationship between the coordinate systems of adjacent laser tracker stations is obtained. The stations are rotated in sequence to obtain the transformation relationship between the coordinate system of each laser tracker station and the global coordinate system. The translation parameters of each laser tracker station coordinate system to the global coordinate system are the global coordinates of each laser tracker station. At the same time, the measurement data of all laser trackers are converted to the global coordinate system through this transformation relationship to obtain the global coordinates of the visible reference points at each laser tracker station, thereby achieving data unification and constructing a global measurement field.

[0079] In this embodiment, based on regional division and multi-station transfer optimization, a preliminary construction of the global measurement field is achieved, which improves the measurement coverage and efficiency and provides a basis for the application of laser polygonal method.

[0080] S5, the global measurement field obtained to step S4 is carried out adjustment optimization, with the laser tracker position global coordinates and the visual reference point global coordinates of this measurement field for optimizing initial value, build measurement field optimization model by laser polygon method, utilize the laser tracker position to the laser interferometry ranging value of visual reference point to solve the optimization correction value of the two coordinates.

[0081] As a preferred implementation of step S5, the specific process includes the following steps:

[0082] S51. Based on the global coordinates of all laser tracker positions and corresponding visual reference points obtained in step S4, and the laser interferometry ranging value obtained by the laser tracker, a measurement equation is established according to the distance formula between two points. The equation is expressed as:

[0083]

[0084] Among them, l ijis the laser interferometry distance from the laser tracker to the visual reference point, (x Sj ,y Sj ,z Sj ) is the three-dimensional coordinate of the laser tracker station, (x pj ,y pj ,z pj ) is the three-dimensional coordinate of the visual reference point, ε ij is the measurement error;

[0085] S52, the global coordinates of the laser tracker station and the visual reference point are used as the initial value of optimization, and the global coordinates of the visual reference point are approximately (x Pi (0) ,y Pi (0) ,z Pi (0) ), the global coordinates of the laser tracker station are approximately (x Sj (0) ,y Sj (0) ,z Sj (0) ), using these two approximate values, the approximate laser interferometry distance value is The measurement equation is linearized and expanded at the above approximate value using Taylor's formula to obtain the error equation:

[0086]

[0087] Among them, (δx Sj ,δy Sj ,δz Sj ) and (δx Pi ,δy Pi ,δz Pi ) is the optimized correction value of the global coordinate approximation of the laser tracker station and the visual reference point, where the coefficients are expressed as follows:

[0088]

[0089] The error equation is expressed as a matrix form: V = A·δX-b; where V is the error vector; A is the coefficient matrix of the error equation, Composition; δX is the global coordinate correction value vector of the laser tracker station and the visual reference point; b is the distance value residual;

[0090] S53, according to the least squares principle formula V T PV=min, and the objective function is obtained:

[0091] (A·δX-b) T P(A·δX-b)=min

[0092] A T PA·δX=A T Pb

[0093] Where P is the laser interferometry distance value l from the laser tracker to the visual reference point ij The weight matrix, if l ij If the measurement is of equal precision, then P takes the unit matrix. ij If the measurement is of unequal precision, then P is determined by l ij The reciprocal of the square of the measurement uncertainty;

[0094] S54. Use regularized ridge estimation to solve the least squares solution of δX, the equation is:

[0095] δX=(A T A+λI) -1 A T b

[0096] Where I is the identity matrix, and the regularization parameter λ is obtained by the L-curve method. The final solution δX is the optimized correction value of the laser tracker station coordinates and the visual reference point coordinates.

[0097] In this embodiment, an adjustment optimization model is constructed by relying on high-precision laser interferometry ranging values, and the stability of the solution is ensured by the regularized ridge estimation method, which effectively improves the accuracy of measurement field construction and solves the problem of difficulty in constructing a global measurement field in complex scenarios.

[0098] In the description of this specification, the reference terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials, or characteristics described may be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification, as well as features of different embodiments or examples, unless they are mutually inconsistent.

[0099] The logic and / or steps represented in the flowchart or otherwise described herein may be considered, for example, as an ordered list of executable instructions for implementing logical functions, and may be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device).

[0100] The above embodiments provide a detailed introduction to the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A method for constructing a global measurement field for complex scenes, characterized in that: The following steps are involved: S1. Based on the measurement space range, multiple target mounts suitable for placing laser tracker laser reflective target balls are fixedly arranged in the scene to serve as visual reference points of the measurement field; S2. Divide the measurement area according to the structure of the measurement object and arrange the laser tracker station in each measurement area; S3, sequentially measuring the three-dimensional coordinate values ​​and laser interferometric ranging values ​​of the visual reference points at different laser tracker positions; S4. Based on the three-dimensional coordinates of the visual reference points at different laser tracker positions, a coordinate conversion model is constructed between the coordinate systems of adjacent laser tracker positions. The coordinate information of the common visual reference points is used to solve the optimized conversion parameters between the adjacent laser tracker positions, and the spatial transformation relationship is obtained to construct a global coordinate system. According to the spatial transformation relationship, the coordinates of each laser tracker position and the visual reference point are converted to the global coordinate system to obtain the corresponding global coordinates, and a global measurement field is constructed. S5, the global measurement field obtained to step S4 is carried out adjustment optimization, with the laser tracker position global coordinates and the visual reference point global coordinates of this measurement field for optimizing initial value, build measurement field optimization model by laser polygon method, utilize the laser tracker position to the laser interferometry ranging value of visual reference point to solve the optimization correction value of the two coordinates.

2. The method for constructing a global measurement field for complex scenes according to claim 1, characterized in that: Step S1 specifically includes: the target seats of the laser tracker laser reflection target ball should be evenly arranged in the measurement space, the positions of any three adjacent target seats cannot be on the same straight line, and the target seats are randomly arranged to ensure that the distances between the target seats are not the same.

3. The method for constructing a global measurement field for complex scenes according to claim 1, characterized in that: Step S2 specifically includes: for the layout of the laser tracker stations, it is required that there are laser tracker stations in different measurement areas and the measurement light of the visible reference points in adjacent measurement areas is not blocked.

4. The method for constructing a global measurement field for complex scenes according to claim 3, characterized in that: There must be at least three common visual reference points between adjacent laser tracker stations. Similarly, there must be at least three common visual reference points between the last laser tracker station and the first laser tracker station.

5. The method for constructing a global measurement field for complex scenes according to claim 1, characterized in that: The specific process of step S3 includes: placing the laser reflective target ball of the laser tracker on the target base, measuring the three-dimensional coordinate value and laser interference ranging value of the visible reference point under the laser tracker station, moving the laser tracker station in sequence, and obtaining the measurement data of the visible reference point under different laser tracker stations.

6. The method for constructing a global measurement field for complex scenes according to claim 1, characterized in that: The specific process of step S4 includes: S41, the three-dimensional coordinates of the visual reference point obtained by the j-th laser tracker station measurement are marked as R j The three-dimensional coordinates of the same visual reference point measured by the j+1th laser tracker station are marked as P j+1 , construct the coordinate transformation model between adjacent laser tracker stations: P j+1 =R j P j +t j ,j=1,2,…,n Among them, R j is the rotation parameter, t j is the translation parameter; S42, using the least squares algorithm to solve the conversion parameters between adjacent laser tracker stations, that is, the rotation parameter R j and the translation parameter t j ; S43. The visual reference point set P1 of the first laser tracker station is transferred through each laser station in sequence according to the conversion parameters, and finally returned to the first laser tracker station in a closed loop to obtain the visual reference point set P′1. In the ideal error-free case, the visual reference point set P1 should be completely equal to P′1. The total number of laser tracker stations is defined as n, and the synthetic rotation is defined as Define the synthetic translation as where R n and t n is the rotation parameter and translation parameter between the n-1th station and the nth station. According to the above closed-loop consistency condition, the calculation expression R is obtained. C P1+t C =P1; S44. Establish the rotation constraint equation R C =I, and translation constraint equation t C =0, where I is a 3×3 identity matrix. The two constraint equations are linearized to obtain the overall constraint equation: in, To optimize the conversion parameters, that is, the correction value vector of the conversion parameters, C is the coefficient matrix, and W is the constant term matrix; S45. Based on the indirect adjustment model with parameters and the overall constraint equation in step S44, introduce the Lagrangian multiplier vector K, and construct the Lagrangian function: Wherein, V is the coordinate correction vector corresponding to the public visual reference point after the coordinate system is converted. In the indirect adjustment model, B is the error equation coefficient matrix, l is the deviation between the coordinates of the public visual reference point after the coordinate conversion model and the measured coordinates, and P is the measurement weight matrix, which is the unit matrix under equal precision measurement. S46, find the partial derivative of the Lagrangian function Φ constructed in step S45 and set it to zero, and solve to obtain the optimized conversion parameter The expression: S47, taking the first laser tracker station coordinate system as the global coordinate system, and optimizing the conversion parameters solved in step S46 Combined with the coordinate transformation model constructed in step S41, the spatial transformation relationship between the coordinate systems of adjacent laser tracker stations is obtained. The stations are rotated in sequence to obtain the transformation relationship between the coordinate system of each laser tracker station and the global coordinate system. The translation parameters of each laser tracker station coordinate system to the global coordinate system are the global coordinates of each laser tracker station. At the same time, the measurement data of each laser tracker is converted to the global coordinate system through this transformation relationship to obtain the global coordinates of the visible reference points at each laser tracker station, thereby achieving data unification and constructing a global measurement field.

7. The method for constructing a global measurement field for complex scenes according to claim 1, characterized in that: The specific process of step S5 includes the following steps: S51. Based on the global coordinates of all laser tracker positions and corresponding visual reference points obtained in step S4, and the laser interferometry ranging value obtained by the laser tracker, a measurement equation is established according to the distance formula between two points. The equation is expressed as: Among them, l ij is the laser interferometry distance from the laser tracker to the visual reference point, (x Sj ,y Sj ,z Sj ) is the three-dimensional coordinate of the laser tracker station, (x pj ,y pj ,z pj ) is the three-dimensional coordinate of the visual reference point, ε ij is the measurement error; S52, the global coordinates of the laser tracker station and the visual reference point are used as the initial value of optimization, and the global coordinates of the visual reference point are approximately (x Pi (0) ,y Pi (0) ,z Pi (0) ), the global coordinates of the laser tracker station are approximately (x Sj (0) ,y Sj (0) ,z Sj (0) ), using these two approximate values, the approximate laser interferometry distance value is The measurement equation is linearized and expanded at the above approximate value using Taylor's formula to obtain the error equation: Among them, (δx Sj ,δy Sj ,δz Sj ) and (δx Pi ,δy Pi ,δz Pi ) is the optimized correction value of the global coordinate approximation of the laser tracker station and the visual reference point, where the coefficients are expressed as follows: The error equation is expressed as a matrix form: V = A·δX-b; where V is the error vector; A is the coefficient matrix of the error equation, Composition; δX is the global coordinate correction value vector of the laser tracker station and the visual reference point; b is the distance value residual; S53, according to the least squares principle formula V T PV=min, and the objective function is obtained: (A·δX-b) T P(A·δX-b)=min A T PA·δX=A T Pb Where P is the laser interferometry distance value l from the laser tracker to the visual reference point ij The weight matrix, if l ij If the measurement is of equal precision, then P takes the unit matrix. ij If the measurement is of unequal precision, then P is determined by l ij The reciprocal of the square of the measurement uncertainty; S54. Use regularized ridge estimation to solve the least squares solution of δX, the equation is: δX=(A T A+λI) -1 A T b Where I is the identity matrix, and the regularization parameter λ is obtained by the L-curve method. The final solution δX is the optimized correction value of the laser tracker station coordinates and the visual reference point coordinates.

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