A large-scale structure spatial posture online compensation system and method based on multi-laser trackers

Abstract

The present invention provides a large-scale structure spatial posture online compensation system based on multiple laser trackers, including a numerical control positioner, a laser tracker, a reflective target ball, a ball joint and a large structure; one laser tracker corresponds to one reflective target ball and is installed close to the transmitting target ball; the numerical control positioner is connected to the large structure through a ball joint; the reflective target balls are provided in multiple numbers and are dispersedly installed on the large structure; wherein the numerical control positioner and the laser tracker are provided with at least 3 groups. At the same time, a method of the above system is also provided, which can avoid the low efficiency caused by single-point measurement and iterative posture adjustment in the traditional large-scale structure posture adjustment and positioning method, and at the same time, the posture adjustment trajectory can be detected and compensated in real time, thereby ensuring the positioning accuracy of the large structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of online compensation of spatial posture of large structures, and in particular relates to an online compensation system and method for spatial posture of large structures based on multiple laser trackers. Background Art

[0002] Large-scale aerospace equipment is manufactured in sections and then assembled by docking large structures. The assembly quality largely determines the final performance of the equipment. Among them, large-structure attitude adjustment and positioning is one of the main tasks of large-scale equipment assembly. The attitude adjustment accuracy largely determines the final performance and service life of the equipment. In the large-scale structure automated assembly system, CNC positioners are usually used as actuators to achieve large-scale structure spatial attitude adjustment and positioning. Due to errors in the manufacture and installation of positioners, the attitude adjustment accuracy of large structures usually cannot meet the requirements. The current mainstream technical means is to use a single laser tracker to measure the attitude control points on the large structure point by point and calculate its current spatial position and attitude (abbreviated as: attitude). The attitude adjustment mechanism drives the positioner to adjust it to the predetermined spatial attitude according to the deviation between the current attitude of the large structure and the target attitude.

[0003] Due to the lack of correction of the attitude trajectory during the attitude adjustment process, the final attitude error is relatively large. In order to ensure the positioning accuracy of large structures, it is often necessary to adjust the attitude repeatedly. However, this large-scale structure positioning method of point-by-point measurement and iterative attitude adjustment has the problem of low measurement and attitude adjustment efficiency, and cannot meet the development and mass production needs of major aerospace models. Summary of the invention

[0004] Technical solution: In order to solve the technical problems of low efficiency and inability to monitor and compensate for posture deviations in real time in the above-mentioned traditional large-scale structure posture adjustment and positioning methods, the present invention provides an online compensation method for large-scale structure spatial posture based on multiple laser trackers, which uses multiple laser trackers to continuously measure the corresponding reflective target balls on the large structure, and calculate the real-time posture deviation of the large structure, and then compensate for the positioning error, which specifically includes:

[0005] A large-scale structure spatial posture online compensation system based on multiple laser trackers comprises a numerical control positioner, a laser tracker, a reflective target sphere, a ball joint and a large-scale structure; one laser tracker corresponds to one reflective target sphere and is installed close to a transmitting target sphere; the numerical control positioner is connected to the large-scale structure through a corresponding ball joint; a plurality of reflective target spheres are provided and are dispersedly installed on the large-scale structure; and at least three groups of numerical control positioners and laser trackers are provided.

[0006] As an improvement, three numerical control positioners, four laser trackers and four reflective target balls are installed.

[0007] At the same time, a compensation method for the above-mentioned large-scale structure spatial posture online compensation system based on multiple laser trackers is also provided, and the specific steps are as follows:

[0008] Step 1: Use multiple laser trackers to continuously measure the corresponding reflective target balls on the large structure to obtain the real-time spatial position of the large structure;

[0009] Step 2: Calculate the parameters in the posture adjustment trajectory polynomial through the initial state and target space posture to obtain the theoretical trajectory of large-scale structure posture adjustment;

[0010] Step 3: According to the theoretical trajectory obtained in step 2 and the real-time spatial pose obtained in step 1, the deviation of the theoretical pose of the large structure relative to its own coordinate system under k-cycle period is calculated through the conversion of the homogeneous transformation matrix and the spatial pose. The deviation is the pose compensation of the large structure under k-cycle period.

[0011] Step 4: Using the results obtained in steps 1 and 3, calculate the posture adjustment of the large structure from the k cycle to the k+1 cycle;

[0012] Step 5: The posture adjustment amount between any two cycles in step 4 is calculated through the kinematic model of the posture adjustment mechanism to obtain the target displacement of the joints of the posture adjustment mechanism in each cycle and complete the real-time positioning.

[0013] As an improvement, in step 1, the coordinates constructed include: the global coordinate system Og-xyz of the reference coordinate system, the local coordinate system Oc-xyz of the large structure, and the base coordinate system Ob-xyz; the specific method for solving the real-time spatial pose of the large structure is: the coordinate P of the fixed reflective target sphere i in the local coordinate system Oc-xyz is known i c , where i = {1, 2, 3, 4}; multiple laser trackers are used to continuously measure the corresponding reflective target balls on the large structure, and the coordinates of the reflective target ball i in the global coordinate system Og-xyz can be obtained as P i g ; Finally, the real-time spatial position of the large structure is calculated based on the singular value decomposition method and the coordinate system transformation principle.

[0014] As an improvement, in step 1, the calculation process includes:

[0015] (1) Install four reflective target balls and arrange four laser trackers at the assembly site. After debugging, each laser tracker can continuously measure a reflective target ball during the large-scale structure adjustment process;

[0016] (2) It is known that the coordinates of the reflective target sphere i in the local coordinate system of the large structure are: The coordinates of the corresponding reflective target ball measured by the laser tracker in the global coordinate system are: According to the coordinate system transformation principle, P i c and P i g The following relations are satisfied:

[0017]

[0018] (3) Use singular value decomposition to calculate the attitude matrix of the large structure relative to the global coordinate system and the position vector

[0019] (4) According to the rigid body rotation principle, the attitude matrix of the large structure relative to the global coordinate system and position vector T c g Expressed as

[0020]

[0021] T c g =[xyz] T Formula 3

[0022] Among them, (x, y, z) is the position of the large structure coordinate system relative to the global coordinate system, (α, β, γ) is the attitude angle of the large structure coordinate system relative to the global coordinate system, then the spatial posture of the large structure relative to the global coordinate system can be expressed by a six-dimensional vector:

[0023] w=[xy zα β γ] T Formula 4

[0024] As an improvement, in step 2, the calculation process includes:

[0025] (1) In order to ensure the continuity of the acceleration of the large-scale structure, the trajectory of the large-scale structure posture adjustment can be expressed by a fifth-order polynomial. Expressed as

[0026]

[0027] Where t is the time of attitude adjustment, and {a0, a1La5} are the trajectory parameters of attitude adjustment of large structures;

[0028] (2) The laser tracker measures the coordinates of the corresponding reflective target ball on the large structure in the initial state: The initial spatial position of the large structure is calculated as w0 according to Formula 1 to Formula 3;

[0029] (3) The target spatial position of the known large structure is w n , the total time of attitude adjustment is t e, then the trajectory parameters are calculated as

[0030]

[0031] in

[0032]

[0033] (4) The cycle period of positioning accuracy compensation of large structures is T. In the kth cycle period, the theoretical spatial position of the large structure is expressed as

[0034]

[0035] Where k is a natural number and k≤floor(t e / T), floor(t e / T) represents t e / The integer part of T.

[0036] As an improvement, in step 3, the calculation process includes:

[0037] (1) In the kth cycle of the attitude adjustment mechanism control system, the coordinates of the corresponding reflective target ball i in the global coordinate system are measured by a laser tracker: According to formula 1 to formula 3, the posture matrix and position vector of the large structure coordinate system relative to the global coordinate system are calculated as follows: and Written in the form of a homogeneous transformation matrix:

[0038]

[0039] (2) According to the theoretical spatial posture of the large structure in the kth cycle, the theoretical posture matrix and position vector of the large structure in the kth cycle can be calculated using Formula 2 to Formula 3. and Written in the form of a homogeneous transformation matrix:

[0040]

[0041] (3) The deviation of the theoretical position of a large structure at the kth period relative to its own coordinate system can be expressed by the homogeneous transformation matrix:

[0042]

[0043] (4) According to the properties of the homogeneous transformation matrix and Formula 2 and Formula 3, the deviation of the theoretical position of the large structure in the kth period relative to its own coordinate system is obtained as

[0044]

[0045] That is, the spatial posture compensation of the large structure in each cycle.

[0046] As an improvement, in step 4, the calculation process includes:

[0047] (1) According to the theoretical trajectory of the large structure, the change in the theoretical position of the large structure in the k+1th period relative to its theoretical position in the kth period is expressed by the homogeneous transformation matrix:

[0048]

[0049] (2) According to the properties of the homogeneous transformation matrix and Formula 2 and Formula 3, the adjustment amount of the theoretical position of the large structure in the k+1th period relative to its theoretical position in the kth period is obtained as follows:

[0050]

[0051] From the kth period to the k+1th period, the position adjustment of the large structure relative to its own coordinate system is:

[0052]

[0053] As an improvement, in step 5, the calculation process includes:

[0054] (1) The kinematic model of the posture adjustment mechanism composed of multiple positioners is w b =f(d1,d2Ld j ), where w b is the end of the attitude adjustment mechanism (i.e., the large structure) in the attitude adjustment mechanism base coordinate system O b -xyz spatial pose, d1, d2Ld j is the displacement of the j joints of the posture adjustment mechanism, and the inverse kinematic solution of the posture adjustment mechanism is obtained as:

[0055] (d1,d2Ld j ) = f -1 (w b )Formula 16

[0056] where f -1 is the inverse function of function f;

[0057] (2) Assume that the joint displacement of the posture adjustment mechanism fed back by the control system in the kth cycle is (d 1,k ,d 2,k Ld j,k ), then according to the kinematic model of the attitude adjustment mechanism, the spatial posture of the large structure in the basic coordinate system of the attitude adjustment mechanism is calculated as

[0058]

[0059] (3) In the k+1th period, the target position of the corrected large structure in the base coordinate system of the attitude adjustment mechanism is expressed as

[0060]

[0061] (4) According to the inverse kinematic solution of the posture adjustment mechanism (Formula 16), the corrected joint target displacement of the posture adjustment mechanism in the k+1th cycle can be calculated as:

[0062]

[0063] The joint target displacement of each cycle of the control system is calculated according to Formula 17 to Formula 19. The control system drives the positioner to move to the corresponding target position accordingly to complete precise positioning.

[0064] Beneficial effects: The online compensation method for the spatial posture of a large structure based on multiple laser trackers proposed in the present invention is to arrange three or more laser trackers at the large structure assembly site, each laser tracker continuously measures the corresponding reflective target ball on the large structure, and calculates the real-time spatial posture of the large structure. The control system calculates the position compensation amount of each joint of the posture adjustment mechanism according to the deviation between the actual posture of the large structure and the theoretical posture, using the inverse kinematics principle, thereby realizing real-time compensation of the spatial posture of the large structure. This method can avoid the inefficiency caused by single-point measurement and iterative posture adjustment in traditional large-structure posture adjustment and positioning methods, and at the same time can perform real-time detection and compensation of the posture adjustment trajectory, which can ensure the positioning accuracy of the large structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a schematic diagram of the process of the present invention.

[0066] Figure 2 It is a schematic diagram of the composition of the online compensation system for the spatial posture of a large structure of the present invention.

[0067] In the figure: a first CNC positioner 1, a second CNC positioner 2, a third CNC positioner 3, a first laser tracker 4, a second laser tracker 5, a third laser tracker 6, a fourth laser tracker 7, a first reflective target sphere 8, a second reflective target sphere 9, a third reflective target sphere 10, a fourth reflective target sphere 11, a large structure 12, a first ball joint 13, a second ball joint 14, and a third ball joint 15. DETAILED DESCRIPTION

[0068] The technical solutions in the embodiments of the present invention will be described clearly and completely below so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the protection scope of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention.

[0069] A large-scale structure spatial posture online compensation system based on multiple laser trackers includes three groups of CNC positioners, four laser trackers, four reflective target balls, a large-scale structure itself 12 and a ball joint 13; one of the laser trackers corresponds to one reflective target ball, and each CNC positioner is connected to the large-scale structure through a corresponding ball joint to form a parallel posture adjustment mechanism; a single positioner can move in the X\Y\Z directions according to a predetermined program, and the spatial posture of the large-scale structure can be adjusted through the coordinated movement between the CNC positioners; the reflective target balls are installed on the large-scale structure and are distributed throughout the large-scale structure as much as possible; the laser tracker should be as close to the measured reflective target ball as possible, and it is necessary to ensure that the laser tracker will not interfere with the measurement of the corresponding reflective target ball during the posture adjustment process of the large-scale structure.

[0070] See Figure 2 As shown, the large-scale structure spatial posture online compensation system based on multiple laser trackers includes a large-scale structure 12; 3 groups of CNC positioners, namely a first CNC positioner 1, a second CNC positioner 2, and a third CNC positioner 3; 4 laser trackers, namely a first laser tracker 4, a second laser tracker 5, a third laser tracker 6, and a fourth laser tracker 7; 4 reflective target balls, namely a first reflective target ball 8, a second reflective target ball 9, a third reflective target ball 10, and a fourth reflective target ball 11; 4 groups of ball joints, namely a first ball joint 13, a second ball joint 14, and a third ball joint 15; the CNC positioners are connected to the large-scale structure through corresponding ball joints to form a parallel posture adjustment mechanism.

[0071] The global coordinate system Og-xyz in the figure is the reference coordinate system in the entire assembly space; the local coordinate system Oc-xyz of the large structure in the figure is the coordinate system consolidated with the large structure itself, which moves with the adjustment of the large structure's own posture, and represents the position and posture of the large structure; the base coordinate system Ob-xyz in the figure is a reference reference system in the workspace of the attitude adjustment mechanism, which is used to describe the position and posture of the end of the attitude adjustment mechanism. In the attitude adjustment system, the local coordinate system of the large structure and the end coordinate system of the attitude adjustment mechanism coincide.

[0072] See Figure 1 As shown, the calculation process of the present invention is as follows:

[0073] Step 1: Use multiple laser trackers to continuously measure the corresponding reflective target balls on the large structure to obtain the real-time spatial position of the large structure;

[0074] Step 2: Calculate the parameters in the posture adjustment trajectory polynomial through the initial state and target space posture to obtain the theoretical trajectory of real-time posture adjustment of large structures;

[0075] Step 3: According to the theoretical trajectory obtained in step 2 and the real-time spatial pose obtained in step 1, the deviation of the theoretical pose of the large structure relative to its own coordinate system under k-cycle period is calculated through the conversion of the homogeneous transformation matrix and the spatial pose. The deviation is the pose compensation of the large structure under k-cycle period.

[0076] Step 4: Using the results obtained in step 3 and step 1, calculate the posture adjustment amount from the large-scale structure cycle k to the next cycle k+1; where k=k+1, in computer language, assign the value of k+1 to k, that is, enter the next cycle. k=0, in computer language, sets the initial cycle.

[0077] Step 5: The posture adjustment amount between any two cycles in step 4 is calculated through the kinematic model of the posture adjustment mechanism to obtain the target displacement of the joints of the posture adjustment mechanism in each cycle and complete the real-time positioning.

[0078] Example 1

[0079] Step 1: Use multiple laser trackers to continuously measure the corresponding reflective target balls on the large structure to obtain the real-time spatial position of the large structure, as follows:

[0080] ①First, four reflective target balls are installed on the large structure, and four laser trackers are arranged at the assembly site. It is necessary to ensure that each laser tracker can perform uninterrupted measurement on the corresponding reflective target ball during the posture adjustment of the large structure.

[0081] ② The coordinates of the reflective target sphere in the large structure coordinate system Oc-xyz are P1 c =[-1253,635,68] T , The laser tracker measures the coordinates of the corresponding reflective target sphere i in the global coordinate system Og-xyz as follows: Where i = {1, 2, 3, 4}. According to the coordinate system transformation principle, the coordinate P of the reflective target sphere i in the local coordinate system of the large structure is i c and the coordinates P in the global coordinate system i g The following relations are satisfied:

[0082]

[0083] ③ The singular value decomposition (SVD) method can be used to calculate the attitude matrix of the large structure coordinate system relative to the global coordinate system and the position vector

[0084] ④ According to the rigid body rotation principle, the attitude matrix of the large structure relative to the global coordinate system and position vector T c g It can be expressed as

[0085]

[0086] T c g =[xyz] T Formula 3

[0087] Among them, (x, y, z) is the position of the large structure coordinate system relative to the global coordinate system, and (α, β, γ) is the attitude angle of the large structure coordinate system relative to the global coordinate system. Therefore, the spatial posture of the large structure relative to the global coordinate system can be expressed by a six-dimensional vector

[0088] w=[xy zα β γ] T Formula 4.

[0089] Step 2: Calculate the theoretical trajectory of large-scale structural posture adjustment, as follows:

[0090] ① In order to ensure the continuity of the posture adjustment trajectory, speed and acceleration of large structures, the trajectory of large structure posture adjustment is a 5th-order polynomial Then the posture adjustment trajectory of the large structure can be expressed as

[0091]

[0092] Where t is the time for attitude adjustment, and {a0, a1La5} are the trajectory parameters for attitude adjustment of large structures.

[0093] ②In the initial state, the coordinates of the reflective target ball on the large structure measured by the laser tracker are:

[0094]

[0095] According to formula (1) to formula (3), the initial spatial pose of the large structure is calculated as follows:

[0096] w0=[1735.892,431.689,734.982,0.1689,-0.1045,0.0680]

[0097] ③The target spatial position of the large structure is w n=[1350,639,620,0,0,0] T , the total time of attitude adjustment is t e = 100 seconds, the trajectory parameters can be calculated as:

[0098]

[0099] ④ The cycle period of positioning accuracy compensation of large structures is T = 0.1s, so the posture adjustment trajectory points of large structures can be expressed as

[0100]

[0101] Where k is a natural number and k≤1000.

[0102] Step 3: Calculate the posture compensation of the large structure in each cycle. The following is an example of k = 575 cycles. The details are as follows:

[0103] ① In the 575th cycle of positioning accuracy compensation, the coordinates of the reflective target sphere measured by the laser tracker in the global coordinate system are

[0104]

[0105] According to formula 1 to formula 3, the attitude matrix and position vector of the large structure relative to the global coordinate system can be calculated as follows:

[0106]

[0107]

[0108] Written in the form of a homogeneous transformation matrix:

[0109]

[0110] ② According to the theoretical posture adjustment trajectory of the large structure (Formula 8), the theoretical spatial posture of the large structure in the 575th cycle can be calculated as

[0111] w 575 =[1489.48843399867,564.063264486699,661.562920730332,

[0112] 0.0610523060917970,-0.0377736292871094,0.0245799692968750]

[0113] Using Formula 2 to Formula 3, the theoretical attitude matrix and position vector of the large structure in the 575th cycle can be calculated as follows:

[0114]

[0115]

[0116] Written in the form of a homogeneous transformation matrix:

[0117]

[0118] ③ Therefore, in the 575th cycle, the deviation of the theoretical position of the large structure relative to its own coordinate system can be expressed by the homogeneous transformation matrix as

[0119]

[0120] ④ According to the properties of the homogeneous transformation matrix and formula 2 and formula 3, the deviation of the theoretical position of the large structure in the 575th period relative to its own coordinate system can be obtained as

[0121]

[0122] That is the spatial posture compensation of the large structure in the 575th period.

[0123] Step 4: Calculate the posture adjustment of the large structure from 575 cycles to 576 cycles, as follows:

[0124] ① According to the theoretical posture adjustment trajectory of the large structure (Formula 8), using Formula 2 and Formula 3, the theoretical spatial posture of the large structure in the 576th cycle can be calculated as

[0125] w 576 =[1488.79750599921,564.434448586127,661.357047133154,0.0607498957305839,-0.0375865251855893,0.0244582173456466]

[0126] Using Formula 2 to Formula 3, it can be calculated that in the 576th cycle, the theoretical posture matrix and position vector of the large structure are

[0127]

[0128]

[0129] In the 576th cycle, the change in the theoretical position of the large structure relative to its theoretical position in the 575th cycle is expressed by the homogeneous transformation matrix:

[0130]

[0131] ② According to the properties of the homogeneous transformation matrix and formula 2 and formula 3, the adjustment amount of the theoretical position of the large structure in the 576th period relative to its theoretical position in the 575th period can be obtained as follows:

[0132]

[0133] Therefore, from the 575th cycle to the 576th cycle, the position adjustment of the large structure relative to its own coordinate system is

[0134]

[0135] Step 5: Calculate the target position of the joint of the posture adjustment mechanism in the 576th cycle, as follows:

[0136] ①The kinematic model of the posture adjustment mechanism composed of three positioners is:

[0137]

[0138] in

[0139]

[0140]

[0141] d1,d2Ld j is the displacement of the jth joint of the posture adjustment mechanism, is the spatial position of the end of the attitude adjustment mechanism (i.e., the large structure) in the attitude adjustment mechanism base coordinate system Ob-xyz. Therefore, in the kth cycle, the kinematic model of the attitude adjustment mechanism can be written as

[0142] The inverse kinematic solution of the posture adjustment mechanism can be obtained as:

[0143]

[0144] where f -1 is the inverse function of function f.

[0145] ② In the 575th cycle, the joint displacement of the posture adjustment mechanism fed back by the control system is

[0146]

[0147] According to the kinematic model of the posture adjustment mechanism The spatial posture of the large structure in the basic coordinate system of the posture adjustment mechanism can be calculated as:

[0148]

[0149] ③ Therefore, in the 575th cycle, the corrected target posture of the large structure in the base coordinate system of the posture adjustment mechanism can be expressed as

[0150]

[0151] ④ Based on the inverse kinematics solution of the posture adjustment mechanism The target displacement of the joint of the posture adjustment mechanism after correction in the 576th cycle can be calculated as

[0152]

[0153] Based on the above calculation example, the target displacement of the joints of the posture adjustment mechanism in each cycle of the control system can be calculated. The control system drives the positioner to move to the corresponding target position based on this, thereby realizing real-time and accurate positioning of large structures.

[0154] Experimental results analysis

[0155] After the large-scale structure posture adjustment is completed, the deviation between the measured value and the theoretical value of the reflection target sphere coordinates can be used to characterize the accuracy of the large-scale structure posture adjustment. The smaller the deviation, the higher the posture adjustment accuracy.

[0156] According to the coordinate system conversion principle, the theoretical coordinates of the reflective target sphere in the global coordinate system after the large-scale structure posture adjustment is completed can be calculated as follows:

[0157]

[0158] Using the positioning compensation method proposed in the present invention, after the large-scale structure posture adjustment is completed, the coordinates of the reflective target ball measured by the laser tracker are

[0159]

[0160] Therefore, after the posture adjustment is completed, the position deviation of the reflective target ball is

[0161]

[0162] The coordinate deviation of each reflective target ball is less than 0.15mm. It takes 1215s to measure the four reflective target balls using four laser trackers, and the adjustment time is 100s, so the total time is 1315s.

[0163] Comparative Example

[0164] For comparison, the large structure is first adjusted to the same initial position using the traditional single-point measurement mode. After the first adjustment, the position deviation of the reflective target ball is measured to be

[0165]

[0166] The first posture adjustment of the large structure took a total of 1254 seconds. In order to make the position deviation of all reflective target balls less than 0.2mm, repeated measurements and posture adjustments are required. After a total of 4 adjustments, the position deviation of the measurement point meets the requirements.

[0167]

[0168] The total time spent on the subsequent four adjustments was 3893 seconds. Using the traditional single-point measurement iterative attitude adjustment method, the total time spent on the attitude adjustment of the large structure was 5147 seconds. Therefore, in order to achieve the same attitude adjustment accuracy, the traditional single-point measurement iterative attitude adjustment method takes much longer than the method proposed in the present invention.

[0169] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An online compensation method for spatial posture of large structures based on multi-laser trackers, Features: The method is based on a large-scale structure spatial posture online compensation system with multiple laser trackers for online compensation measurement. The system includes a numerical control positioner, a laser tracker, a reflective target ball, a ball joint and a large-scale structure; one laser tracker corresponds to one reflective target ball and is installed close to the transmitting target ball; the numerical control positioner is connected to the large-scale structure through a ball joint; a plurality of reflective target balls are provided and are dispersedly installed on the large-scale structure; wherein the numerical control positioner and the laser tracker are both provided with at least three groups; There are three CNC positioners, four laser trackers and four reflective target balls installed; The specific steps of this method are: Step 1: Use multiple laser trackers to continuously measure the corresponding reflective target balls on the large structure to obtain the real-time spatial position of the large structure; Step 2: Calculate the parameters in the posture adjustment trajectory polynomial through the initial state and target space posture to obtain the theoretical trajectory of large-scale structure posture adjustment; Step 3: According to the theoretical trajectory obtained in step 2 and the real-time spatial pose obtained in step 1, the deviation of the theoretical pose of the large structure relative to its own coordinate system under k-cycle period is calculated through the conversion of the homogeneous transformation matrix and the spatial pose. The deviation is the pose compensation of the large structure under k-cycle period. Step 4: Using the results obtained in steps 1 and 3, calculate the posture adjustment of the large structure from the k cycle to the k+1 cycle; Step 5: The posture adjustment amount between any two cycles in step 4 is used to calculate the target displacement of the joints of the posture adjustment mechanism in each cycle through the kinematic model of the posture adjustment mechanism to complete the real-time positioning; Among them, in step 1, the coordinates constructed include: the global coordinate system Og-xyz of the reference coordinate system, the local coordinate system Oc-xyz of the large structure and the base coordinate system Ob-xyz; the specific method for solving the real-time spatial pose of the large structure is: the coordinates P of the fixed reflective target sphere in the local coordinate system Oc-xyz are known i c , use multiple laser trackers to continuously measure the corresponding reflective target balls on large structures, and obtain the coordinate system P of the reflective target balls in the global coordinate system Og-xyz i g ; Finally, the real-time spatial position and posture of large structures are obtained based on the singular value decomposition method and the principle of coordinate system transformation; In step 1, the calculation process includes: (1) Install four reflective target balls and arrange four laser trackers at the assembly site. After debugging, each laser tracker can continuously measure a reflective target ball during the large-scale structure adjustment process; (2) It is known that the coordinates of the reflective target sphere i in the local coordinate system of the large structure are: Where i = {1, 2, 3, 4}, the coordinates of the corresponding reflective target ball measured by the laser tracker in the global coordinate system are: According to the coordinate system transformation principle, P i c and P i g The following relations are satisfied: (3) Use singular value decomposition to calculate the attitude matrix of the large structure relative to the global coordinate system and the position vector (4) According to the rigid body rotation principle, the attitude matrix of the large structure relative to the global coordinate system and the position vector Expressed as Among them, (x, y, z) is the position of the large structure coordinate system relative to the global coordinate system, (α, β, γ) is the attitude angle of the large structure coordinate system relative to the global coordinate system, then the spatial posture of the large structure relative to the global coordinate system can be expressed by a six-dimensional vector: w = [x y z α β γ] T Formula 4; In step 2, the calculation process includes: (1) In order to ensure the continuity of the acceleration of the large-scale structure, the trajectory of the large-scale structure posture adjustment can be expressed by a fifth-order polynomial. Expressed as Where t is the time for attitude adjustment, {a 0 ,a 1 La 5 } is the trajectory parameter for large structure posture adjustment; (2) Assume that the coordinates of the corresponding reflective target sphere on the large structure in the initial state measured by the laser tracker are According to formula 1 to formula 3, the initial spatial position of the large structure is calculated as w 0 ; (3) The target spatial position of the known large structure is w n , the total time of attitude adjustment is t e , then the trajectory parameters are calculated as in (4) The cycle period of positioning accuracy compensation of large structures is T. In the kth cycle period, the theoretical spatial position of the large structure is expressed as Where k is a natural number and k≤floor(t e / T), floor(t e / T) represents t e / The integer part of T; In step 3, the calculation process includes: (1) In the kth cycle of the attitude adjustment mechanism control system, the coordinates of the corresponding reflective target ball in the global coordinate system are measured by a laser tracker: According to formula 1 to formula 3, the posture matrix and position vector of the large structure relative to the global coordinate system are calculated as and Written in the form of a homogeneous transformation matrix: (2) According to the theoretical spatial posture of the large structure in the kth cycle, the theoretical posture matrix and position vector of the large structure in the kth cycle can be calculated using Formula 2 to Formula 3. and Written in the form of a homogeneous transformation matrix: (3) The deviation of the theoretical position of a large structure at the kth period relative to its own coordinate system can be expressed by the homogeneous transformation matrix: (4) According to the properties of the homogeneous transformation matrix and Formula 2 and Formula 3, the deviation of the theoretical position of the large structure in the kth period relative to its own coordinate system is obtained as That is, the spatial posture compensation of the large structure in each cycle.

2. According to the online compensation method for spatial posture of large structures based on multiple laser trackers as described in claim 1, Features: In step 4, the calculation process includes: (1) According to the theoretical trajectory of the large structure, the change in the theoretical position of the large structure in the k+1th period relative to its theoretical position in the kth period is expressed by the homogeneous transformation matrix: (2) According to the properties of the homogeneous transformation matrix and Formula 2 and Formula 3, the adjustment amount of the theoretical position of the large structure in the k+1th period relative to its theoretical position in the kth period is obtained as follows: From the kth period to the k+1th period, the position adjustment of the large structure relative to its own coordinate system is 3. According to the online compensation method for large-scale structure spatial posture based on multi-laser trackers as claimed in claim 2, Features: In step 5, the calculation process includes: (1) The kinematic model of the posture adjustment mechanism composed of multiple positioners is w b =f(d 1 ,d 2 L j ), where w b The end of the posture adjustment mechanism, i.e., the large structure, is in the base coordinate system O of the posture adjustment mechanism. b -xyz spatial pose, d 1 ,d 2 L j is the displacement of the j joints of the posture adjustment mechanism, and the inverse kinematic solution of the posture adjustment mechanism is obtained as (d 1 ,d 2 L j ) = f -1 (w b ) Formula 16 where f -1 is the inverse function of function f; (2) Assume that the joint displacement of the posture adjustment mechanism fed back by the control system in the kth cycle is (d 1,k ,d 2,k L j,k ), then according to the kinematic model of the attitude adjustment mechanism, the spatial posture of the large structure in the basic coordinate system of the attitude adjustment mechanism is calculated as (3) In the k+1th period, the target position of the corrected large structure in the base coordinate system of the attitude adjustment mechanism is expressed as (4) According to the inverse kinematic solution of the posture adjustment mechanism (Formula 16), the corrected joint target displacement of the posture adjustment mechanism in the k+1th cycle can be calculated as: The joint target displacement of each cycle of the control system is calculated according to Formula 17 to Formula 19. The control system drives the positioner to move to the corresponding target position accordingly to complete precise positioning.

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