High-precision measurement system and method for pose of six-degree-of-freedom parallel mechanism

Abstract

The invention relates to the technical field of measuring equipment, in particular to a six-degree-of-freedom parallel mechanism pose high-precision measuring system and method.The six-degree-of-freedom parallel mechanism pose high-precision measuring system comprises a laser emission reference device, an array light spot feature target assembly, a parallel mechanism movable platform and a feature detection and recognition assembly, and the laser emission reference device is arranged at the top of the parallel mechanism fixed platform; the array light spot feature target assembly is arranged above the laser emission standard device and arranged at the bottom of the parallel mechanism movable platform, and the four corners of the bottom of the parallel mechanism movable platform are fixedly connected with the top of the parallel mechanism fixed platform through the six-degree-of-freedom parallel mechanism. The feature detection and recognition assembly is arranged at the bottom of the array light spot feature target assembly and used for recognizing light spot information and target feature information on the array light spot feature target assembly, processing of redundant data is reduced, the measurement period is shortened, and it is ensured that high-precision rapid measurement is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring equipment, and in particular to a high-precision measurement system and method for the posture of a six-degree-of-freedom parallel mechanism. Background Art

[0002] Large-aperture omnidirectional movable radio telescope antennas usually need to work in open-air environments. Since the antenna structure is mainly composed of metal materials such as steel, it is easily affected by environmental loads such as gravity, temperature, wind load, rain and snow, which can cause deformation of the shape of the antenna's main reflector and the sub-reflector support structure, deteriorate the reflector surface accuracy, and cause the microwave optical path to shift and produce misalignment errors, thereby reducing the antenna's gain and causing pointing deviations, resulting in a decrease in the sensitivity of the antenna system. Therefore, it is necessary to install an adjustment mechanism between the sub-surface and the sub-surface support rod, adjust the sub-surface posture through the sub-surface adjustment mechanism, and actively correct the relative positions of the foci of the antenna's main and sub-reflector surfaces and the feed center to compensate for the focusing error caused by structural deformation.

[0003] For antenna systems with high precision requirements, especially large-aperture omnidirectional movable radio telescope antennas, due to the large diameter of the sub-reflector, heavy weight, large adjustment required, and the need for multiple degrees of freedom adjustment, the sub-reflector of the high-precision radio telescope antenna adopts a six-degree-of-freedom parallel mechanism with high rigidity, compact structure, high precision, and multiple degrees of freedom adjustment to adjust the position of the sub-reflector.

[0004] Since the antenna of the large-aperture omnidirectional movable radio telescope is in a complex outdoor working environment (gravity, temperature, wind load, rain and snow) for a long time, there are many factors that cause motion errors in the sub-surface adjustment mechanism under complex environments, and the influencing mechanism is also relatively complex. After the sub-surface adjustment mechanism works for a long time, the wear of the electric cylinder mechanical transmission system and hinges will occur, resulting in an increase in the hinge gap and a decrease in the transmission accuracy of the electric cylinder. Due to the influence of temperature load, the electric cylinder, hinge and other components will be thermally deformed, causing deviations in the mapping of the output posture of the sub-surface adjustment mechanism and the motor displacement. In addition, since the sub-surface adjustment mechanism is installed on the antenna, the load is heavy, and it moves with the main surface of the antenna in pitch, the force characteristics of the sub-surface adjustment mechanism change with the change of the antenna pitch angle, and the terminal posture error also changes with the change of the antenna pitch angle, so that the movement of each dimension of the sub-surface adjustment mechanism will be affected, resulting in posture errors, and the adjusted sub-reflector cannot accurately reach the required posture, thereby affecting the implementation of the overall task. Real-time or quasi-real-time high-precision measurement of the six-degree-of-freedom posture of the moving platform of the sub-reflector adjustment mechanism helps to improve the motion accuracy of the sub-surface adjustment mechanism.

[0005] At present, in most cases, laser trackers and other equipment are used to calibrate the sub-surface adjustment mechanism. However, these measurement methods are slow and cannot be installed on the antenna sub-surface to measure the six-degree-of-freedom posture of the sub-surface adjustment mechanism in real time. They are usually only used for the calibration of geometric errors. If the real-time or quasi-real-time high-precision measurement of the six-degree-of-freedom posture of the parallel mechanism can be achieved, closed-loop control or self-calibration can be achieved, thereby reducing the posture deviation of the sub-surface adjustment mechanism caused by non-geometric errors.

[0006] The parallel adjustment mechanism of the large-aperture antenna sub-surface is the key executive component for realizing the posture adjustment of the optical system of a large-aperture astronomical telescope. This large-scale six-degree-of-freedom posture adjustment system requires more precise, real-time posture measurement in seconds as accurate feedback of its own real-time motion adjustment amount.

[0007] The current conventional and more mature measurement technologies such as laser trackers and laser scanners can determine the position and posture of moving targets within seconds by scanning. The position and posture accuracy within the meter range can often achieve tens of microns. However, they have certain requirements for the measurement environment and are not suitable for long-term operation. The equipment and maintenance costs are high, the equipment size is large, and the position and posture measurement accuracy is low. In addition, the laser tracker needs to be installed with a suitable cooperative target. Photogrammetry methods including binocular measurement or multi-eye measurement can often achieve the same level of measurement accuracy, but the measurement cycle is also longer.

[0008] Therefore, in order to meet the demand for high-precision measurement of the posture of the six-degree-of-freedom parallel mechanism structure, it is necessary to design a new posture measurement system and method, which is more convenient to achieve faster and higher-precision posture measurement on the moving target, so as to complete the real-time feedback and control of the posture adjustment system. Summary of the invention

[0009] In view of this, the present invention aims at the deficiencies in the prior art and proposes a high-precision measurement system and method for the posture of a six-degree-of-freedom parallel mechanism, aiming to solve at least one of the problems raised by the above background technology.

[0010] In a first aspect, the present invention provides a high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism, comprising:

[0011] A laser emission reference device, wherein the laser emission reference device is arranged on the top of the parallel mechanism setting platform;

[0012] An array light spot characteristic target component, wherein the array light spot characteristic target component is arranged above the laser emission reference device;

[0013] A parallel mechanism moving platform, wherein the array light spot characteristic target component is arranged at the bottom of the parallel mechanism moving platform, and the top of the array light spot characteristic target component is fixedly connected to the bottom of the parallel mechanism moving platform, and the four corners of the bottom of the parallel mechanism moving platform are fixedly connected to the top of the parallel mechanism fixed platform through a six-degree-of-freedom parallel mechanism structure;

[0014] A feature detection and identification component is arranged at the bottom of the array light spot feature target component, and the detection end of the feature detection and identification component is arranged toward the array light spot feature target component, and the feature detection and identification component is used to identify the light spot information and target feature information on the array light spot feature target component.

[0015] In some embodiments, the laser emission reference device includes:

[0016] A base, wherein two bases are symmetrically arranged, and the bottoms of the two bases are fixedly connected to the top of the parallel mechanism fixing platform;

[0017] A support frame, the support frame is arranged on the top of the two bases, and the tops of the two bases are fixedly connected to the bottom of the support frame;

[0018] A supporting bottom plate, the supporting bottom plate is arranged inside the supporting frame, and the side wall of the supporting bottom plate is fixedly connected to the inner wall of the supporting frame;

[0019] A reflector, wherein the reflector is arranged on the top of the supporting base plate, and the mounting end of the bottom of the reflector is fixedly connected to the top of the supporting base plate, and the supporting base plate and the axis of the reflector coincide with each other;

[0020] A laser emitting assembly, wherein the laser emitting assembly is arranged on the top of the supporting base plate, and the mounting end at the bottom of the laser emitting assembly is fixedly connected to the top of the supporting base plate. At least one laser emitting assembly is arranged on the top of the supporting base plate, and the laser emitting reference device can emit N non-parallel laser beams through the laser emitting assembly, N ≥ 3, and the laser emitting assembly is a laser module that can emit at least 3 laser beams separately or a beam splitter laser that can emit at least 3 laser beams.

[0021] In some embodiments, the array spot feature target component includes:

[0022] A target plate, the top of which is fixedly connected to the bottom of the parallel mechanism moving platform, the bottom of which is provided with M characteristic marking points, M≥3, and the positions of the characteristic marking points on the target plate are known;

[0023] A laser emitter, wherein at least one laser emitter is provided, the mounting end of the laser emitter is fixedly connected to the bottom of the target plate, and the laser emitter is a laser module that emits at least three laser beams individually or a beam splitter that can emit at least three laser beams.

[0024] In some embodiments, the laser module includes a laser, a laser sleeve, a fixing screw, and an adjusting screw. The laser module is fixedly connected to the top of the supporting base plate or the bottom of the target plate through a plurality of the fixing screws and a plurality of the adjusting screws. The laser sleeve is fixedly installed inside with a laser.

[0025] The laser beam emitted by the laser emission reference device and the array light spot characteristic target component is calibrated in advance and defined as a spatial straight line by fitting.

[0026] In some embodiments, the feature detection and recognition component includes:

[0027] Support frame;

[0028] A camera detector is arranged on the top of the support frame, and the top of the support frame is detachably connected to the camera detector. An optical lens is arranged at the shooting end of the camera detector, and the field of view of the optical lens can cover the target plate characteristic information of the array light spot characteristic target component, as well as the light spot where the laser emitted by the laser emission reference intersects with the target plate, and the light spot where the laser emitted by the array light spot characteristic target component itself intersects with the target plate through the light beam reflected by the reflector.

[0029] In some embodiments, the laser emission reference device has at least three laser beams that illuminate the planar area at the bottom of the target plate in different positions and form at least three complete laser spots, and the centroids of the three intersecting laser spots are not collinear.

[0030] In a second aspect, the present invention provides a high-precision measurement method for the posture of a six-degree-of-freedom parallel mechanism, comprising the following steps:

[0031] Step 1: First calibrate and fit the three-dimensional coordinate equation of the laser beam space. At least three groups of laser emission units emit three laser beams through the laser. The equivalent spatial straight line equation of the emitted laser beam is as follows:

[0032] L1:xj1=Xj10+tj1*Xj1;

[0033] yj1=Yj10+tj1*Yj1;

[0034] zj1=Zj10+tj1*Zj1;

[0035] L2:xj2=Xj20+tj2*Xj2;

[0036] yj2=Yj20+tj2*Yj2;

[0037] zj2=Zj20+tj2*Zj2;

[0038] L3:xj3=Xj30+tj3*Xj3;

[0039] yj3=Yj30+tj3*Yj3;

[0040] zj3=Zj30+tj3*Zj3;

[0041] In the above formula: L1, L2, L3 are the equivalent spatial straight line equations of the three laser beams emitted by the three lasers;

[0042] (xj1, yj1, zj1) are the coordinates of any point on the laser beam spatial straight line L1 in space;

[0043] (xj2, yj2, zj2) are the coordinates of any point on the laser beam spatial straight line L2 in space;

[0044] (xj3, yj3, zj3) are the coordinates of any point of the laser beam spatial straight line L3 in space;

[0045] Xj10, Yj10, Zj10, Xj1, Yj1, Zj1, Xj20, Yj20, Zj20, Xj2, Yj2, Zj2, Xj30, Yj30, Zj30, Xj3, Yj3, Zj3 are the constants of the straight line equation; tj1, tj2, tj3 are the variable parameters of the straight line equation;

[0046] Step 2: Pre-identify or calibrate the characteristic edge or characteristic point of a specific plane area of ​​the target to be measured, and obtain the relative position relationship of the edge or characteristic point; the characteristic point is any position of the plane area to be measured;

[0047] Step 3: Using the relative position relationship of the plane corner points or edge features calibrated in step 2, the feature detection and recognition component directly photographs the target plane to be measured, and calibrates the camera intrinsic parameters and the camera optical system distortion parameters using the known corner point and edge feature position relationship and the two-dimensional image captured by the camera;

[0048] Steps to solve detector distortion based on the double straight line principle:

[0049] 1) Define camera lens distortion as:

[0050]

[0051] Where: (x u ,y u ) is the undistorted image point; (xd ,y d ) is the corresponding distorted image point; 1 and λ 2 is the distortion coefficient; (C x , C y ) is the distortion centre;

[0052] 2) Define the ideal straight line equation of any straight line on the object to be measured in the image as:

[0053] ax u +by u +c=0

[0054] a, b, c are the parameters of the straight line equation;

[0055] 3) Combining steps 1-2, we get:

[0056]

[0057] In the formula,

[0058]

[0059] 4) Use the feature detection and recognition component to extract the edge curve (distorted straight line) corresponding to the ideal straight line on the target image. For any edge curve, (x d，i ,y d，i ), i = 1, 2, ..., n is any point on the edge, satisfying the formula in step 3, we can get:

[0060]

[0061] 5) Using the least square method to solve the distortion coefficients e, f and g in step 4, and using the obtained distortion coefficients to perform distortion correction on the image;

[0062] Step 4: Define a two-dimensional coordinate system using the plane image of the target plate obtained by the feature detection and recognition component, select the intersection formed by the two edges of the specific plane as the two-dimensional coordinate origin, and define the straight line formed by one edge as the X-axis, draw a perpendicular line to the defined X-axis as the Y-axis of the two-dimensional coordinate system, and determine another edge point as the next straight line of the two-dimensional coordinate system, and use this two-dimensional coordinate system to define the two-dimensional position information of the remaining feature points respectively, and the definition of the subsequent measurement quasi-coordinate system remains unchanged. If a two-dimensional coordinate system is defined for a plane feature point, select two feature points, one point is defined as the two-dimensional coordinate origin, and the connecting line is used as the X-axis. Draw a perpendicular line to the defined X-axis as the Y-axis of the two-dimensional coordinate system, and determine the coordinates of the third feature point of the three feature points in the two-dimensional coordinate system;

[0063] Step 5: Under the two-dimensional coordinate system established in step 4, using image processing technology, according to the image obtained by the feature detection and recognition component, determine the location of the centroid of the spot formed by the intersection of the three laser beams emitted by the laser on the plane area of ​​the target to be measured. The two-dimensional coordinates based on the target board system coordinate system are recorded as:

[0064] P01: (x01, y01), P02: (x02, y02), P03: (x03, y03);

[0065] Step 6: Through the equivalent space straight line equation established in step 1 and the position coordinates obtained in step 5, the spatial coordinates of the center of mass of the light spots where the three laser beams intersect the plane area of ​​the target to be measured are calculated by using the principle that the length of the same space line segment is equal under different coordinate systems with proportional factors. The spatial coordinates are defined as the spatial coordinates of the center of mass of the three light spots of the target to be measured, which are recorded as: Pq01: (xq01, yq01, zq01), Pq02: (xq02, yq02, zq02), Pq03: (xq03, yq03, zq03);

[0066] The specific calculation process is as follows:

[0067] According to the principle that the length of space line segments is equal:

[0068] (xq01-xq02)^2+(yq01-yq02)^2+(zq01-zq02)^2=(x02-x01)^2+(y02-y01)^2;

[0069] (xq03-xq02)^2+(yq03-yq02)^2+(zq03-zq02)^2=(x02-x03)^2+(y02-y03)^2;

[0070] (xq03-xq01)^2+(yq03-yq01)^2+(zq03-zq01)^2=(x01-x03)^2+(y01-y03)^2;

[0071] Combined with the three laser fitting space straight line equations, the spatial coordinates of any three points in the plane area of ​​the target to be measured based on the laser emission reference coordinate system can be calculated, Pq01: (xq01, yq01, zq01), Pq02: (xq02, yq02, zq02), Pq03: (xq03, yq03, zq03);

[0072] Step 8: The coordinates of the three light spots in the target board coordinate system are P01: (x01, y01, 0), P02: (x02, y02, 0), and P03: (x03, y03, 0). Using the BURSA principle, the coordinates of the common points in the two coordinate systems can be solved to obtain the position translation and attitude deviation in the two coordinate systems.

[0073]

[0074] Where (X Ti , Y Ti , Z Ti ) are the three-dimensional coordinates of the three light spots in the laser emission reference coordinate system, (X i , Y i , Z i ) is the three-dimensional coordinate based on the target board system coordinate system (defined as Z i =0); (ΔX, ΔY, ΔZ) are the position translations of the two coordinate systems of the launch and target, k is the calculation scale factor of the two coordinate systems, (ε X , ε Y , ε Z ) is the attitude deviation angle of the launch and target coordinate systems;

[0075] Step 9: Repeat steps 3-8, and use the position translation and attitude deviation angle of the target board coordinate system relative to the launch reference coordinate system solved under different attitudes to obtain the target's 3-DOF position information and 3-DOF attitude information;

[0076] Step 10: Define an edge of the target board as the X-axis of the target board system coordinate system, define the corner point of this edge and the adjacent edge as the origin, take the plane of the target board as the XOY plane, and the direction perpendicular to the plane of the target board as the Z-axis to establish the target board system coordinate system;

[0077] Step 11: Define the laser beams emitted by the three lasers on the target board system as L 5 , L 6 , L 7 ;

[0078] Step 12: Using Laser Beam L 5 For example, the rotation matrix R and translation matrix T between the target plate system coordinate system and the laser emission system coordinate system are obtained by the stereo structured light method to solve the laser beam L 5 The spatial straight line equation in the laser emission system coordinate system:

[0079] The conversion relationship between the target board coordinate system and the laser launch system coordinate system is as follows:

[0080]

[0081] in, Represents the coordinates in the target board coordinate system, Represents the coordinates in the laser launch system coordinate system;

[0082] R is a 3×3 rotation matrix, which describes the rotation relationship between the target board coordinate system and the laser emission system coordinate system:

[0083]

[0084] T is the translation vector, which describes the translation relationship from the target board coordinate system to the laser emission system coordinate system:

[0085]

[0086] Define the spatial straight line equation L of the laser beam in the target plate coordinate system 5 as follows:

[0087] X 1 =a1s 1 +b 1

[0088] Y 1 =c 1 s 1 +d 1

[0089] Z 1 =s 1

[0090] The L in the target plate coordinate system 5 The form converted to the laser launch system coordinate system is as follows:

[0091]

[0092] The three coordinate components are:

[0093] X 2 =(r 11 a 1 +r 12 c 1 +r 13 )S 1 +(r 11 b 1 +r 12 d 1 +t 1 ),

[0094] Y 2 =(r 21 a 1 +r 22 c 1 +r 23 )S 1+(r 21 b 1 +r 22 d 1 +t 2 ),

[0095] Z 2 =(r 31 a 1 +r 32 c 1 +r 33 )S 1 +(r 31 b 1 +r 32 d 1 +t 3 ).

[0096] Solve to get the laser beam L 5 The equation in the laser launch system coordinate system is:

[0097] X 2 =A 2 S 1 +B 2 ,

[0098] Y 2 =C 2 S 1 +D 2 ,

[0099] Z 2 =E 2 S 1 +F 2 .

[0100] in,

[0101] A 2 =r 11 a 1 +t 12 c 1 +r 13 , B 2 =r 11 b 1 +r 12 d 1 +t 1 ,

[0102] C 2 =r 21 a 1 +r 22 c 1 +r 23 , D 2 =r 21 b 1 +r 22d 1 +t 2 ,

[0103] E 2 =r 31 a 1 +r 32 c 1 +r 33 , F 2 =r 31 b 1 +r 32 d 1 +t 3 .

[0104] Step 13: Define the reflector plane as the plane with Z=0 in the laser emission system coordinate system, then the laser beam L 5 The equation of the spatial straight line after reflection by the reflector is L′ 5 :

[0105] X′ 2 =X 2 =A 2 S 1 +B 2 ,

[0106] Y′ 2 =Y 2 =C 2 S 1 +D 2 ,

[0107] Z′ 2 =-Z 2 =-(E 2 S 1 +F 2 ).

[0108] Step 14: Use the stereo structured light method to solve the equation of the target plane in the laser emission system coordinate system. The target plane M 1 for:

[0109] M 1 : A 3 x+B 3 y+C 3 z+D 3 =0

[0110] Step 15: Solve for the Laser Beam L' 5 After being reflected by the reflector, it is aligned with the target plate plane M 1 The intersection coordinates P 5 (x 5 ,y 5 , z 5 );

[0111] Among them, the intersection point P 5 (x 5 ,y 5 , z 5 ) satisfies the laser beam L′ 5 The equation of a straight line in space,

[0112] x 5 =X 2 ′=A 2 S 1 +B 2 ,

[0113] y 5 =Y 2 ′=C 2 S 1 +D 2

[0114] z 5 =Z 2 ′=-(E 2 S 1 +F 2 ).

[0115] x 5 ,y 5 , z 5 Substitute the target plate plane equation A 3 x+B 3 y+C 3 z+D 3 =0:

[0116] A 3 (A 2 S 1 +B 2 )+B 3 (C 2 S 1 +D 2 )+C 3 (-(E 2 S 1 +F 2 ))+D 3 =0

[0117] After expansion:

[0118] (A 3 A 2 +B 3 C 2 -C 3 E 2 )S 1 +(A 3 B 2 +B 3 D 2 -C3 F 2 +D 3 )=0

[0119] Solve for parameter S 1 Then, substitute the intersection coordinate formula to get the intersection coordinates:

[0120]

[0121] in:

[0122] k 1 =A 3 A 2 +B 3 C 2 1C 3 E 2 ,

[0123] k 2 =A 3 B 2 +B 3 D 2 -C 3 F 2 +D 3 .

[0124] Step 16: Using the stereo structured light method, the position change of the target plate under the laser emission system is solved as Δx, Δy, Δz, α, β, γ;

[0125] Step 17: According to the posture change in step 16, Δx, Δy, Δz, α, β, γ, the rotation matrix R′ and translation matrix T′ representing the posture change of the target board system in the laser emission system coordinate system are:

[0126] in:

[0127]

[0128] Step 18: Calculate the laser beam L according to the rotation matrix R′ and translation matrix T′ obtained in step 17 5 The linear equation of the laser beam space after the posture transformation is L″ 5 :

[0129] The laser beam L 5 The equation of a straight line (X 2 , Y 2 , Z 2 ) into the rotation and translation formulas:

[0130]

[0131] The spatial straight line equation L″ of the laser beam after the posture transformation 5 for:

[0132] X 3 = A 3 S 1 + B 3 ,

[0133] Y 3 = C 3 S 1 + D 3 ,

[0134] Z 3 = E 3 S 1 + F 3

[0135] Wherein:

[0136] A 3 = r 11 A 2 + r 12 C 2 + r 13 E 2 ,B 3 = r 11 B 2 + r 12 D 2 + r 13 F 2 + Δx

[0137] C 3 = r 21 A 2 + r 22 C 2 + r 23 E 2 ,D 3 = r 21 B 2 + r 22 D 2 + r 23 F 2 + Δy

[0138] E 3 = r 31 A 2 + r 32 C 2 + r 33 E 2 ,F 3 = r 31 B 2 + r 32 D 2 + r 33 F 2 + Δz

[0139] Step 19: Laser Beam L″ 5 The equation of the spatial straight line after reflection by the reflector becomes L″ 5 :

[0140] X 3 =A 3 S 1 +B 3 ,

[0141] Y 3 =C 3 S 1 +D 3 ,

[0142] Z 3 =-E 3 S 1 -F 3

[0143] Step 20: After the target plane changes its posture, the target plane M 1 The plane equation in the laser launch system coordinate system becomes:

[0144] M′ 1 : A 3 ′x+B 3 ′y+C 3 ′z+D 3 ′=0

[0145] in: D 3 ′=D 3 -(A 3 ′Δx+B 3 ′Δy+C 3 ′Δz)

[0146] Step 21: Solve for the laser beam L″′ 5 With plane M′ 1 The intersection coordinates P′ 5 (x′ 5 , y′ 5 , z′ 5 )for:

[0147]

[0148] in:

[0149] K 1 ′=A 3 'A 3 +B 3 ′C 3 -C 3 ′E 3 ,

[0150] K2 ′=A 3 'B 3 +B 3 'D 3 -C 3 ′F 3 +D 3 '

[0151] Step 22: According to the camera detector, the distance between the laser beam and the light spot on the target plate plane after the posture change is ΔL 1 ;

[0152] Step 23: Combine steps 16 and 21 to obtain the intersection coordinates P before and after the posture change 5 (x 5 ,y 5 , z 5 ), P′ 5 (x′ 5 , y′ 5 , z′ 5 ) and the distance ΔL in step 23 1 , we can get:

[0153]

[0154] The relationship can be written as:

[0155]

[0156] The above relationship can be written as follows:

[0157] F 1 (α, β, γ) = 0

[0158] Step 24: Repeat steps 12-23 to obtain laser beam L 6 , L 7 With ΔL 2 , ΔL 3 Equations for α, β, and γ:

[0159] F 2 (α, β, γ) = 0

[0160] F 3 (α, β, γ) = 0

[0161] Step 25: Transform the equations in steps 23-24 into:

[0162] F(α, β, γ) = F 1 +F 2 +F 3 =0

[0163] Step 26: The angles α, β, and γ can be solved by using the Gauss-Newton nonlinear least squares algorithm; finally, the position information of the array spot feature target component relative to the laser emission reference device is obtained;

[0164] Step 27: Repeat steps 3-26, and use the position translation and attitude deviation angle of the target plate coordinate system relative to the launch reference coordinate system solved under different postures to obtain the 3-DOF position information and 3-DOF attitude information of the target, and feed back the 6-DOF array spot feature target component posture information, i.e. the parallel mechanism moving platform posture information, to the 6-DOF parallel mechanism structure in real time for motion adjustment;

[0165] Step 28: Measure the posture information and convert it into the posture adjustment information of the six-degree-of-freedom parallel mechanism structure:

[0166] The parallel mechanism base coordinate system {B} is located on the parallel mechanism fixed platform. The parallel mechanism base coordinate system {B} is the reference datum of other coordinate systems. The moving platform coordinate system {P} is located on the parallel mechanism moving platform. {M} is the laser emission reference coordinate system of the measurement system. {T} is the target plate coordinate system. The relative position of the target plate coordinate system and the moving platform coordinate system is fixed.

[0167] The transformation relationship between coordinate systems is represented by the homogeneous transformation matrix. The posture transformation relationship from the moving platform coordinate system {P} to the base coordinate system {B} is expressed by To express, similarly, the pose transformation from the target board coordinate system {T} to the base coordinate system {B} is expressed as The pose transformation from the target plate coordinate system {T} to the moving platform coordinate system {P} is expressed as Indicates that the pose transformation matrix is:

[0168]

[0169] The above coordinate system transformation relationship satisfies:

[0170]

[0171] Combined with the pose transformation matrix, it can be expressed as:

[0172]

[0173] From formula 2, we can get:

[0174]

[0175] Similarly, in the laser emission reference coordinate system, (5) and (6) can be expressed as

[0176]

[0177] Combining equations (5)-(8), we can obtain the rotation matrix and translation matrix of the six-degree-of-freedom parallel mechanism structure:

[0178]

[0179] The measured posture information can be converted into the posture information of the six-degree-of-freedom parallel mechanism structure through equations (9) and (10), where and is the rotation matrix and translation matrix calculated from the 3-DOF posture information and 3-DOF position information obtained in step 27, is a fixed value and can be obtained based on the measurement results of multiple pose points.

[0180] Compared with the prior art, the present invention has the following beneficial effects:

[0181] 1. The present invention uses a laser emission reference device, a target to be measured, and a feature detection and recognition component to form a moving target (including plane characteristics) posture measurement system. The laser beam group composed of multiple laser emission units covers the moving target motion range, and the laser spot on the plane area of ​​the target to be measured is obtained through the feature detection and recognition component. The edge characteristics of the plane area of ​​the target to be measured and the conversion relationship of the photo are used to obtain the coordinate position change information of the emitted laser spot using an image processing method, thereby obtaining the motion change information of the plane area of ​​the target to be measured, and finally realizing the fast and high-precision posture measurement of the moving target. The laser group emission system can use commercial lasers, and the laser beam performance is stable and the cost is relatively low.

[0182] 2. The present invention installs a target plate system. The target plate can use a plane plate or a plane target point with a feature mark. The feature information of the plane plate or the target point is calibrated in advance. The cost is low and stable. The target plate system can be determined according to the measurement requirements and the six-degree-of-freedom space, and the practicability is strong.

[0183] 4. The present invention is applicable to measuring targets of different ranges. The multiple lasers emitted by the laser group emission system can cover a large area of ​​the plane area of ​​the target to be measured and its motion range. By adjusting the field of view of the detection device and the laser posture, as long as the field of view of the detection device can completely cover the entire plane area of ​​the target to be measured and its motion range, the postures of targets of different ranges and sizes can be measured. Therefore, the measurement scheme has good scalability, good adaptability and strong practicality.

[0184] 5. The measuring principle of the present invention is the laser beam calibration principle and the space line segment equality principle, the calculation is relatively simple and the versatility is strong.

[0185] 6. In the system of the present invention, a group of signals effectively acquired in the plane area of ​​the target to be measured includes at least 3 light spots, and the centers of the three light spots are connected to form a plane. The limited laser light spot capture of the target to be measured is conducive to rapid measurement. The system of the embodiment of the present invention can be provided with 4 laser beams, which can form multiple redundant planes, thereby providing multiple sets of data for analysis and optimization, further improving the measurement accuracy, and the measurement method is simple.

[0186] 7. The coordinate systems involved in the present invention are all based on the laser emission space coordinate system, so the measurement results are stable and accurate.

[0187] 8. The present invention uses feature detection and recognition components to directly acquire images, and does not make any requirements on the external orientation parameters of the camera itself, thereby reducing the requirements for the stability of the camera position. The internal orientation parameters only need to correct the distortion parameters, and can be directly calibrated quickly and adaptively through the edge characteristics of the planar area. The detection system has strong environmental adaptability.

[0188] 9. The present invention only needs a feature detection and recognition component to directly obtain the target's complete plane edge information and the relative two-dimensional coordinate information of the light spot, and couple the three-dimensional coordinate information of the laser beam space. The calculation is simple, the processing of redundant data is reduced, the measurement cycle is shortened, and rapid measurement is ensured.

[0189] 10. The feature detection and recognition component and the laser emission reference are independent, but the feature detection and recognition component only needs to cover enough feature points and laser spots of the target to be measured. Therefore, the position setting of the feature detection and recognition component is not fixed and has fewer restrictions. It can be set according to the distance and space of the target to be measured, which reduces the measurement space restriction requirements. The feature detection and recognition component and the laser emission reference can even be placed at one end for easy power supply, centralized control and later maintenance.

[0190] 11. The laser launch system module is connected to the Invar base plate by an Invar support tube. The connection method is three-top and three-pull screw connection, which is convenient for adjusting the laser pointing in the initial state. After the adjustment, the structural rigidity is high, the launch point position and laser beam pointing are stable and reliable, and the thermal adaptability is high, which is conducive to ensuring the long-term position measurement accuracy.

[0191] 12. A reflector is provided on the laser emission system. The reflector is rigidly connected to the laser emission end. After the reference is calibrated in the early stage, the relative position can be stable for a long time, which is beneficial to improve the accuracy of posture measurement.

[0192] 13. By setting up multiple laser beams on the target board and amplifying the transmission distance through reflectors, the position measurement data with 1 times the accuracy can be obtained.

[0193] 14. The laser spot reflected back to the target board can be captured and received by the detector at the same time as the laser module array laser at the base transmitting end directly hitting the target board, which improves the simplicity and work efficiency of the system equipment. It can also ensure the consistency of position measurement and posture measurement time.

[0194] 15. The spot change information on the target board is obtained by using the laser beam information at the transmitting end of the base to obtain high-precision position change information, and the high-precision attitude change information of the target board can be separated.

[0195] The target plate adopts a high-precision calibrated Invar flat plate with finely processed edges, clear and high straightness. It can be used as a reference ruler to use edge information to complete the optical system distortion correction well, and has high time and thermal stability, which is beneficial to improve the accuracy and stability of the measurement system.

[0196] The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure.

[0197] Other features and aspects of the present disclosure will become more apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0198] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0199] Figure 1 A front view of a high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism provided in an embodiment of the present invention;

[0200] Figure 2 Axonometric diagram of a high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism provided in an embodiment of the present invention;

[0201] Figure 3 Axonometric diagram of a high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism provided in an embodiment of the present invention;

[0202] Figure 4 Axonometric diagram of a high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism provided in an embodiment of the present invention;

[0203] Figure 5 A schematic diagram of a coordinate system for a high-precision position and posture measurement system of a six-degree-of-freedom parallel mechanism provided in an embodiment of the present invention;

[0204] Figure 6 Schematic diagram of the coordinate system of the high-precision measurement system of the posture of the six-degree-of-freedom parallel mechanism provided in an embodiment of the present invention.

[0205] Among them: 1. Laser emission reference; 2. Parallel mechanism fixed platform; 3. Parallel mechanism moving platform; 4. Six-degree-of-freedom parallel mechanism structure; 5. Base; 6. Support frame; 7. Support bottom plate; 8. Reflector; 9. Laser emission component; 10. Target plate; 11. Laser emitter; 12. Laser sleeve; 13. Fixing screw; 14. Adjusting screw; 15. Support frame; 16. Camera detector; 17. Array spot feature target component; 18. Feature detection and recognition component; 19. Laser module; 20. Feature marker point. DETAILED DESCRIPTION

[0206] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0207] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0208] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0209] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0210] See also Figure 1-6 As shown, the first embodiment

[0211] A high-precision position and posture measurement system of a six-degree-of-freedom parallel mechanism according to an embodiment of the present application includes:

[0212] A laser emission reference device 1, wherein the laser emission reference device 1 is arranged on the top of the parallel mechanism setting platform 2;

[0213] An array light spot characteristic target component 17, wherein the array light spot characteristic target component 17 is arranged above the laser emission reference device 1;

[0214] The parallel mechanism moving platform 3, the array light spot characteristic target component 17 is arranged at the bottom of the parallel mechanism moving platform 3, and the top of the array light spot characteristic target component 17 is fixedly connected to the bottom of the parallel mechanism moving platform 3, and the four corners of the bottom of the parallel mechanism moving platform 3 are fixedly connected to the top of the parallel mechanism fixed platform 2 through a six-degree-of-freedom parallel mechanism structure 4; wherein the six-degree-of-freedom parallel mechanism structure 4 realizes the posture change of the parallel mechanism moving platform 3 relative to the parallel mechanism fixed platform 2 through the coordinated extension and contraction of the six-rod cylinder, the six-degree-of-freedom parallel mechanism structure 4 is the existing technology, and the six-degree-of-freedom parallel mechanism structure 4 can make the posture of the parallel mechanism moving platform 3 change arbitrarily.

[0215] A feature detection and identification component 18 is arranged at the bottom of the array light spot feature target component 17, and the detection end of the feature detection and identification component 18 is arranged toward the array light spot feature target component 17, and the feature detection and identification component 18 is used to identify the light spot information and target feature information on the array light spot feature target component 17.

[0216] In some specific embodiments, the laser emission reference device 1 includes:

[0217] A base 5, wherein two bases 5 are symmetrically arranged, and the bottoms of the two bases 5 are fixedly connected to the top of the parallel mechanism fixing platform 2;

[0218] A support frame 6, wherein the support frame 6 is disposed on the top of the two bases 5, and the tops of the two bases 5 are fixedly connected to the bottom of the support frame 6;

[0219] A supporting bottom plate 7, wherein the supporting bottom plate 7 is disposed inside the supporting frame 6, and a side wall of the supporting bottom plate 7 is fixedly connected to an inner wall of the supporting frame 6;

[0220] A reflector 8, wherein the reflector 8 is disposed on the top of the supporting base plate 7, and a mounting end at the bottom of the reflector 8 is fixedly connected to the top of the supporting base plate 7, and the axis of the supporting base plate 7 coincides with the axis of the reflector 8;

[0221] A laser emitting assembly 9, wherein the laser emitting assembly 9 is arranged on the top of the supporting base plate 7, and the mounting end at the bottom of the laser emitting assembly 9 is fixedly connected to the top of the supporting base plate 7, and at least one laser emitting assembly 9 is arranged on the top of the supporting base plate 7, through which the laser emitting reference device 1 can emit N non-parallel laser beams, N≥3, and the laser emitting assembly 9 is a laser module 19 for emitting at least 3 laser beams separately or a beam splitting laser capable of emitting at least 3 laser beams.

[0222] The support base plate 7 is made of low expansion coefficient invar material and is a flat plate structure, which is provided with mounting holes adapted to the laser emission assembly 9, holes for installing the reflector 8, and an interface connected to the support frame 6. The base 5 is provided with a mounting interface connected to the parallel mechanism fixed platform 2.

[0223] In some specific embodiments, the array spot feature target component 17 includes:

[0224] A target plate 10, the top of which is fixedly connected to the bottom of the parallel mechanism moving platform 3, the bottom of which is provided with M characteristic marking points, M≥3, and the positions of the characteristic marking points on the target plate are known;

[0225] The laser emitter 11 is provided with at least one laser emitter 11, the mounting end of the laser emitter 11 is fixedly connected to the bottom of the target plate 10, and the laser emitter 11 is a laser module 19 that emits at least three laser beams individually or a beam splitter laser that can emit at least three laser beams.

[0226] The target board 10 is provided with a mounting interface connected to the parallel mechanism moving platform 3 .

[0227] In some specific embodiments, the laser module 19 includes a laser, a laser sleeve 12, a fixing screw 13, and an adjusting screw 14. The laser module 19 is fixedly connected to the top of the supporting base plate 7 or the bottom of the target plate 10 through a plurality of the fixing screws 13 and a plurality of the adjusting screws 14. A laser is fixedly installed inside the laser sleeve 12; the position and direction of the laser are adjusted in a three-top and three-pull manner.

[0228] The laser beam emitted by the laser emission reference device 1 and the array light spot characteristic target component 17 is calibrated in advance and defined as a spatial straight line by fitting.

[0229] In some specific embodiments, the feature detection and recognition component 18 includes:

[0230] Support frame 15;

[0231] A camera detector 16, wherein the camera detector 16 is arranged on the top of the support frame 15, and the top of the support frame 15 and the camera detector 16 are detachably connected, and an optical lens is arranged at the shooting end of the camera detector 16, and the field of view of the optical lens can cover the characteristic information of the target plate 10 of the array light spot characteristic target component 17, as well as the light spot where the laser emitted by the laser emission reference device 1 intersects with the target plate 10, and the light spot where the laser emitted by the array light spot characteristic target component 17 itself intersects with the target plate 10 through the light beam reflected by the reflector 8.

[0232] The support frame 15 and the camera detector 16 are arranged in cooperation with each other. The support frame 15 and the camera detector 16 can be in any position so that the detection end of the camera detector 16 corresponds to the array light spot characteristic target component 17 .

[0233] In some specific embodiments, the laser emission reference device 1 has at least three laser beams irradiating the planar area at the bottom of the target plate 10 in different postures and forming at least three complete laser spots, and the centroids of the three intersecting laser spots are not collinear.

[0234] Second embodiment

[0235] A high-precision posture measurement method for a six-degree-of-freedom parallel mechanism according to an embodiment of the present application includes the following steps:

[0236] Step 1: First calibrate and fit the three-dimensional coordinate equation of the laser beam space. At least three groups of laser emission units emit three laser beams through the laser. The equivalent spatial straight line equation of the emitted laser beam is as follows:

[0237] L1:xj1=Xj10+tj1*Xj1;

[0238] yj1=Yj10+tj1*Yj1;

[0239] zj1=Zj10+tj1*Zj1;

[0240] L2:xj2=Xj20+tj2*Xj2;

[0241] yj2=Yj20+tj2*Yj2;

[0242] zj2=Zj20+tj2*Zj2;

[0243] L3:xj3=Xj30+tj3*Xj3;

[0244] yj3=Yj30+tj3*Yj3;

[0245] zj3=Zj30+tj3*Zj3;

[0246] In the above formula: L1, L2, L3 are the equivalent spatial straight line equations of the three laser beams emitted by the three lasers;

[0247] (xj1, yj1, zj1) are the coordinates of any point on the laser beam spatial straight line L1 in space;

[0248] (xj2, yj2, zj2) are the coordinates of any point on the laser beam spatial straight line L2 in space;

[0249] (xj3, yj3, zj3) are the coordinates of any point of the laser beam spatial straight line L3 in space;

[0250] Xj10, Yj10, Zj10, Xj1, Yj1, Zj1, Xj20, Yj20, Zj20, Xj2, Yj2, Zj2, Xj30, Yj30, Zj30, Xj3, Yj3, Zj3 are the constants of the straight line equation; tj1, tj2, tj3 are the variable parameters of the straight line equation;

[0251] Step 2: Pre-identify or calibrate the characteristic edges or characteristic points of the specific plane area of ​​the target to be measured, and obtain the relative position relationship of the edges or characteristic points; the characteristic points are any positions in the plane area to be measured; the characteristic points are any positions in the plane area to be measured; they can be on the edge or inside the plane, and the characteristic points need to be clear, accurate, easy to identify, and stable.

[0252] Step 3: Using the relative position relationship of the plane corner points or edge features calibrated in step 2, the feature detection and recognition component directly photographs the target plane to be measured, and calibrates the camera intrinsic parameters and the camera optical system distortion parameters using the known corner point and edge feature position relationship and the two-dimensional image captured by the camera;

[0253] Steps to solve detector distortion based on the double straight line principle:

[0254] 1) Define camera lens distortion as:

[0255]

[0256] Where: (x u ,y u ) is the undistorted image point; (x d ,y d ) is the corresponding distorted image point; 1 and λ 2 is the distortion coefficient; (C x , C y) is the distortion centre;

[0257] 2) Define the ideal straight line equation of any straight line on the object to be measured in the image as:

[0258] ax u +by u +c=0

[0259] a, b, c are the parameters of the straight line equation;

[0260] 3) Combining steps 1-2, we get:

[0261]

[0262] In the formula,

[0263]

[0264] 4) Use the feature detection and recognition component to extract the edge curve (distorted straight line) corresponding to the ideal straight line on the target image. For any edge curve, (x d，i ,y d，i ), i = 1, 2, ..., n is any point on the edge, satisfying the formula in step 3, we can get:

[0265]

[0266] 5) Using the least square method to solve the distortion coefficients e, f and g in step 4, and using the obtained distortion coefficients to perform distortion correction on the image;

[0267] Step 4: Define a two-dimensional coordinate system using the plane image of the target plate obtained by the feature detection and recognition component, select the intersection formed by the two edges of the specific plane as the two-dimensional coordinate origin, and define the straight line formed by one edge as the X-axis, draw a perpendicular line to the defined X-axis as the Y-axis of the two-dimensional coordinate system, and determine another edge point as the next straight line of the two-dimensional coordinate system, and use this two-dimensional coordinate system to define the two-dimensional position information of the remaining feature points respectively, and the subsequent measurement quasi-coordinate system definition remains unchanged. If a two-dimensional coordinate system is defined for a plane feature point, select two feature points, define one point as the two-dimensional coordinate origin, connect the line as the X-axis, draw a perpendicular line to the defined X-axis as the Y-axis of the two-dimensional coordinate system, and determine the coordinates of the third feature point in the two-dimensional coordinate system; it includes two aspects, one is to use the edge and two feature points to determine the X-axis, but two straight lines and three points are required to determine a surface, so defining the Y-axis must simultaneously determine another edge and feature point.

[0268] Step 5: Under the two-dimensional coordinate system established in step 4, using image processing technology, according to the image obtained by the feature detection and recognition component, determine the location of the centroid of the spot formed by the intersection of the three laser beams emitted by the laser on the plane area of ​​the target to be measured. The two-dimensional coordinates based on the target board system coordinate system are recorded as:

[0269] P01: (x01, y01), P02: (x02, y02), P03: (x03, y03);

[0270] Step 6: Through the equivalent space straight line equation established in step 1 and the position coordinates obtained in step 5, the spatial coordinates of the center of mass of the light spots where the three laser beams intersect the plane area of ​​the target to be measured are calculated by using the principle that the length of the same space line segment is equal under different coordinate systems with proportional factors. The spatial coordinates are defined as the spatial coordinates of the center of mass of the three light spots of the target to be measured, which are recorded as: Pq01: (xq01, yq01, zq01), Pq02: (xq02, yq02, zq02), Pq03: (xq03, yq03, zq03);

[0271] The specific calculation process is as follows:

[0272] According to the principle that the length of space line segments is equal:

[0273] (xq01-xq02)^2+(yq01-yq02)^2+(zq01-zq02)^2=(x02-x01)^2+(y02-y01)^2;

[0274] (xq03-xq02)^2+(yq03-yq02)^2+(zq03-zq02)^2=(x02-x03)^2+(y02-y03)^2;

[0275] (xq03-xq01)^2+(yq03-yq01)^2+(zq03-zq01)^2=(x01-x03)^2+(y01-y03)^2;

[0276] Combined with the three laser fitting space straight line equations, the spatial coordinates of any three points in the plane area of ​​the target to be measured based on the laser emission reference coordinate system can be calculated, Pq01: (xq01, yq01, zq01), Pq02: (xq02, yq02, zq02), Pq03: (xq03, yq03, zq03);

[0277] Step 8: The coordinates of the three light spots in the target board coordinate system are P01: (x01, y01, 0), P02: (x02, y02, 0), and P03: (x03, y03, 0). Using the BURSA principle, the coordinates of the common points in the two coordinate systems can be solved to obtain the position translation and attitude deviation in the two coordinate systems.

[0278]

[0279] Where (X Ti , Y Ti , Z Ti ) are the three-dimensional coordinates of the three light spots in the laser emission reference coordinate system, (X i , Y i , Z i ) is the three-dimensional coordinate based on the target board system coordinate system (defined as Z i =0); (ΔX, ΔY, ΔZ) are the position translations of the two coordinate systems of the launch and target, k is the calculation scale factor of the two coordinate systems, (ε X , ε Y , ε Z ) is the attitude deviation angle of the launch and target coordinate systems;

[0280] Step 9: Repeat steps 3-8, and use the position translation and attitude deviation angle of the target board coordinate system relative to the launch reference coordinate system solved under different attitudes to obtain the target's 3-DOF position information and 3-DOF attitude information;

[0281] Step 10: Define an edge of the target board as the X-axis of the target board system coordinate system, define the corner point of this edge and the adjacent edge as the origin, take the plane of the target board as the XOY plane, and the direction perpendicular to the plane of the target board as the Z-axis to establish the target board system coordinate system;

[0282] Step 11: Define the laser beams emitted by the three lasers on the target board system as L 5 , L 6 , L 7 ;

[0283] Step 12: Using Laser Beam L 5 For example, the rotation matrix R and translation matrix T between the target plate system coordinate system and the laser emission system coordinate system are obtained by the stereo structured light method to solve the laser beam L 5 The spatial straight line equation in the laser emission system coordinate system:

[0284] The conversion relationship between the target board coordinate system and the laser launch system coordinate system is as follows:

[0285]

[0286] in, Represents the coordinates in the target board coordinate system, Represents the coordinates in the laser launch system coordinate system;

[0287] R is a 3×3 rotation matrix, which describes the rotation relationship between the target board coordinate system and the laser emission system coordinate system:

[0288]

[0289] T is the translation vector, which describes the translation relationship from the target board coordinate system to the laser emission system coordinate system:

[0290]

[0291] Define the spatial straight line equation L of the laser beam in the target plate coordinate system 5 as follows:

[0292] X 1 =a 1 s 1 +b 1

[0293] Y 1 =c 1 S 1 +d 1

[0294] Z 1 =s 1

[0295] The L in the target plate coordinate system 5 The form converted to the laser launch system coordinate system is as follows:

[0296]

[0297] The three coordinate components are:

[0298] X 2 =(r 11 a 1 +r 12 c 1 +r 13 )S 1 +(r 11 b 1 +r 12 d 1 +t 1 ),

[0299] Y 2 =(r 21 a 1 +r 22 c 1 +r 23 )S1 +(r 21 b 1 +r 22 d 1 +t 2 ),

[0300] Z 2 =(r 31 a 1 +r 32 c 1 +r 33 )S 1 +(r 31 b 1 +r 32 d 1 +t 3 ).

[0301] Solve to get the laser beam L 5 The equation in the laser launch system coordinate system is:

[0302] X 2 =A 2 S 1 +B 2 ,

[0303] Y 2 =C 2 S 1 +D 2 ,

[0304] Z 2 =E 2 S 1 +F 2 ·

[0305] in,

[0306] A 2 =r 11 a 1 +r 12 c 1 +r 13 , B 2 =r 11 b 1 +r 12 d 1 +t 1 ,

[0307] C 2 =r 21 a 1 +r 22 c 1 +r 23 , D 2 =r 21 b 1 +r22 d 1 +t 2 ,

[0308] E 2 =r 31 a 1 +r 32 c 1 +r 33 , F 2 =r 31 b 1 +r 32 d 1 +t 3 .

[0309] Step 13: Define the reflector plane as the plane with Z=0 in the laser emission system coordinate system, then the laser beam L 5 The equation of the spatial straight line after reflection by the reflector is L′ 5 :

[0310] X′ 2 =X 2 =A 2 S 1 +B 2 ,

[0311] Y′ 2 =Y 2 =C 2 S 1 +D 2 ,

[0312] Z′ 2 =-Z 2 =-(E 2 S 1 +F 2 ).

[0313] Step 14: Use the stereo structured light method to solve the equation of the target plane in the laser emission system coordinate system. The target plane M 1 for:

[0314] M 1 : A 3 x+B 3 y+C 3 z+D 3 =0

[0315] Step 15: Solve for the Laser Beam L' 5 After being reflected by the reflector, it is aligned with the target plate plane M 1 The intersection coordinates P 5 (x 5 ,y 5 , z 5 );

[0316] Among them, the intersection point P 5 (x 5 , y5 , z 5 ) satisfies the laser beam L′ 5 The equation of a straight line in space,

[0317] x 5 =X 2 ′=A 2 S 1 +B 2 ,

[0318] y 5 =Y 2 ′=C 2 S 1 +D 2

[0319] z 5 =Z 2 ′=-(E 2 S 1 +F 2 ).

[0320] x 5 ,y 5 , z 5 Substitute the target plate plane equation A 3 x+B 3 y+C 3 z+D 3 =0:

[0321] A 3 (A 2 S 1 +B 2 )+B 3 (C 2 S 1 +D 2 )+C 3 (-(E 2 S 1 +F 2 ))+D 3 =0

[0322] After expansion:

[0323] (A 3 A 2 +B 3 C 2 -C 3 E 2 )S 1 +(A 3 B 2 +B 3 D 2 -C3 F 2 +D 3 )=0

[0324] Solve for parameter S 1 Then, substitute the intersection coordinate formula to get the intersection coordinates:

[0325]

[0326] in:

[0327] k 1 =A 3 A 2 +B 3 C 2 -C 3 E 2 ,

[0328] k 2 =A 3 B 2 +B 3 D 2 -C 3 F 2 +D 3 .

[0329] Step 16: Using the stereo structured light method, the position change of the target plate under the laser emission system is solved as Δx, Δy, Δz, α, β, γ;

[0330] Step 17: According to the posture change in step 16, Δx, Δy, Δz, α, β, γ, the rotation matrix R′ and translation matrix T′ representing the posture change of the target board system in the laser emission system coordinate system are:

[0331] in:

[0332]

[0333] Step 18: Calculate the laser beam L according to the rotation matrix R′ and translation matrix T′ obtained in step 17 5 The linear equation of the laser beam space after the posture transformation is L″ 5 :

[0334] The laser beam L 5 The equation of a straight line (X 2 , Y 2 , Z 2 ) into the rotation and translation formulas:

[0335]

[0336] The spatial straight line equation L″ of the laser beam after the posture transformation 5 for:

[0337] X 3 = A 3 S 1 + B 3 ,

[0338] Y 3 = C 3 S 1 + D 3 ,

[0339] Z 3 = E 3 S 1 + F 3

[0340] Wherein:

[0341] A 3 = r 11 A 2 + r 12 C 2 + r 13 E 2 ,B 3 = r 11 B 2 + r 12 D 2 + r 13 F 2 + Δx

[0342] C 3 = r 21 A 2 + r 22 C 2 + r 23 E 2 ,D 3 = r 21 B 2 + r 22 D 2 + r 23 F 2 + Δy

[0343] E 3 = r 31 A 2 + r 32 C 2 + r 33 E 2 ,F 3 = r 31 B 2 + r 32 D 2 + r 33 F 2 + Δz

[0344] Step 19: Laser Beam L ″5 The equation of the spatial straight line after reflection by the reflector becomes L″′ 5 :

[0345] X 3 =A 3 S 1 +B 3 ,

[0346] Y 3 =C 3 S 1 +D 3 ,

[0347] Z 3 =-E 3 S 1 -F 3

[0348] Step 20: After the target plane changes its posture, the target plane M 1 The plane equation in the laser launch system coordinate system becomes:

[0349] M′ 1 : A 3 ′x+B 3 ′y+C 3 ′z+D 3 ′=0

[0350] in: D 3 ′=D 3 -(A 3 ′Δx+B 3 ′Δy+C 3 ′Δz)

[0351] Step 21: Solve for the laser beam L″′ 5 With plane M′ 1 The intersection coordinates P′ 5 (x′ 5 , y′ 5 , z′ 5 )for:

[0352]

[0353] in:

[0354] K 1 ′=A 3 'A 3 +B 3 ′C 3 -C 3 ′E 3 ,

[0355] K2 ′=A 3 'B 3 +B 3 'D 3 -C 3 ′F 3 +D 3 '

[0356] Step 22: According to the camera detector, the distance between the laser beam and the light spot on the target plate plane after the posture change is ΔL 1 ;

[0357] Step 23: Combine steps 16 and 21 to obtain the intersection coordinates P before and after the posture change 5 (x 5 ,y 5 , z 5 ), P′ 5 (x′ 5 , y′ 5 , z′ 5 ) and the distance ΔL in step 23 1 , we can get:

[0358]

[0359] The relationship can be written as:

[0360]

[0361] The above relationship can be written as follows:

[0362] F 1 (α, β, γ) = 0

[0363] Step 24: Repeat steps 12-23 to obtain laser beam L 6 , L 7 With ΔL 2 , ΔL 3 Equations for α, β, and γ:

[0364] F 2 (α, β, γ) = 0

[0365] F 3 (α, β, γ) = 0

[0366] Step 25: Transform the equations in steps 23-24 into:

[0367] F(α, β, γ) = F 1 +F 2 +F 3 =0

[0368] Step 26: The angles α, β, and γ can be solved by using the Gauss-Newton nonlinear least squares algorithm; finally, the position information of the array spot feature target component relative to the laser emission reference device is obtained;

[0369] Step 27: Repeat steps 3-26, and use the position translation and attitude deviation angle of the target plate coordinate system relative to the launch reference coordinate system solved under different postures to obtain the 3-DOF position information and 3-DOF attitude information of the target, and feed back the 6-DOF array spot feature target component posture information, i.e. the parallel mechanism moving platform posture information, to the 6-DOF parallel mechanism structure in real time for motion adjustment;

[0370] Step 28: Measure the posture information and convert it into the posture adjustment information of the six-degree-of-freedom parallel mechanism structure:

[0371] The parallel mechanism base coordinate system {B} is located on the parallel mechanism fixed platform. The parallel mechanism base coordinate system {B} is the reference datum of other coordinate systems. The moving platform coordinate system {P} is located on the parallel mechanism moving platform. {M} is the laser emission reference coordinate system of the measurement system. {T} is the target plate coordinate system. The relative position of the target plate coordinate system and the moving platform coordinate system is fixed.

[0372] The transformation relationship between coordinate systems is represented by the homogeneous transformation matrix. The posture transformation relationship from the moving platform coordinate system {P} to the base coordinate system {B} is expressed by To express, similarly, the pose transformation from the target board coordinate system {T} to the base coordinate system {B} is expressed as The pose transformation from the target plate coordinate system {T} to the moving platform coordinate system {P} is expressed as Indicates that the pose transformation matrix is:

[0373]

[0374] The above coordinate system transformation relationship satisfies:

[0375]

[0376] Combined with the pose transformation matrix, it can be expressed as:

[0377]

[0378] From formula 2, we can get:

[0379]

[0380] Similarly, in the laser emission reference coordinate system, (5) and (6) can be expressed as

[0381]

[0382] Combining equations (5)-(8), we can obtain the rotation matrix and translation matrix of the six-degree-of-freedom parallel mechanism structure:

[0383]

[0384] The measured posture information can be converted into the posture information of the six-degree-of-freedom parallel mechanism structure through equations (9) and (10), where and is the rotation matrix and translation matrix calculated from the 3-DOF posture information and 3-DOF position information obtained in step 27, is a fixed value and can be obtained based on the measurement results of multiple pose points.

[0385] The implementation principle of the present invention is:

[0386] The measurement system is mainly composed of a laser emission reference, an array spot feature target component, and a feature detection and recognition component. The measurement system emits more than three light beams (the spatial straight line has been calibrated) from a laser emission reference installed on a fixed platform to illuminate the array spot feature target component fixed on a moving platform, which contains clear (calibrated in advance) plane edges and target feature point information. The feature detection and recognition component that can cover the entire motion range of the array spot feature target component is used to identify the spot information on the target marking system plane. The acquired information contains the complete target plane edge information and the relative two-dimensional position information of the laser spot. The two-dimensional coordinates of the center of mass of the spot are quickly defined by image processing, and the three-dimensional spatial straight line information of the laser beam is coupled to directly obtain the three-dimensional spatial coordinates of the spot where the laser beam intersects with the target surface, thereby obtaining the three-degree-of-freedom position information of the target to be measured. At the same time, at least three laser beams emitted from the array spot feature target component hit the fixed reflective mirror on the laser emission reference and are reflected to the target plate on the array spot feature target component. The feature detection and recognition component also recognizes its two-dimensional change information, and combines the determined measurement distance to solve the three-degree-of-freedom posture information of the target plate, and finally completes the fast and ultra-high-precision six-degree-of-freedom posture measurement of the six-degree-of-freedom parallel mechanism structure.

[0387] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A high-precision position measurement system for a six-degree-of-freedom parallel mechanism, characterized in that: include: A laser emission reference device, wherein the laser emission reference device is arranged on the top of the parallel mechanism setting platform; An array light spot characteristic target component, wherein the array light spot characteristic target component is arranged above the laser emission reference device; A parallel mechanism moving platform, wherein the array light spot characteristic target component is arranged at the bottom of the parallel mechanism moving platform, and the top of the array light spot characteristic target component is fixedly connected to the bottom of the parallel mechanism moving platform, and the four corners of the bottom of the parallel mechanism moving platform are fixedly connected to the top of the parallel mechanism fixed platform through a six-degree-of-freedom parallel mechanism structure; A feature detection and identification component is arranged at the bottom of the array light spot feature target component, and the detection end of the feature detection and identification component is arranged toward the array light spot feature target component, and the feature detection and identification component is used to identify the light spot information and target feature information on the array light spot feature target component.

2. A high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism according to claim 1, characterized in that: The laser emission reference device comprises: A base, wherein two bases are symmetrically arranged, and the bottoms of the two bases are fixedly connected to the top of the parallel mechanism fixing platform; A support frame, the support frame is arranged on the top of the two bases, and the tops of the two bases are fixedly connected to the bottom of the support frame; A supporting bottom plate, the supporting bottom plate is arranged inside the supporting frame, and the side wall of the supporting bottom plate is fixedly connected to the inner wall of the supporting frame; A reflector, wherein the reflector is arranged on the top of the supporting base plate, and the mounting end of the bottom of the reflector is fixedly connected to the top of the supporting base plate, and the supporting base plate and the axis of the reflector coincide with each other; A laser emitting assembly, wherein the laser emitting assembly is arranged on the top of the supporting base plate, and the mounting end at the bottom of the laser emitting assembly is fixedly connected to the top of the supporting base plate. At least one laser emitting assembly is arranged on the top of the supporting base plate, and the laser emitting reference device can emit N non-parallel laser beams through the laser emitting assembly, N ≥ 3, and the laser emitting assembly is a laser module that can emit at least 3 laser beams separately or a beam splitter laser that can emit at least 3 laser beams.

3. A high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism according to claim 2, characterized in that: The array light spot characteristic target component comprises: A target plate, the top of which is fixedly connected to the bottom of the parallel mechanism moving platform, the bottom of which is provided with M characteristic marking points, M≥3, and the positions of the characteristic marking points on the target plate are known; A laser emitter, wherein at least one laser emitter is provided, the mounting end of the laser emitter is fixedly connected to the bottom of the target plate, and the laser emitter is a laser module that emits at least three laser beams individually or a beam splitter that can emit at least three laser beams.

4. A high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism according to claim 3, characterized in that: The laser module comprises a laser, a laser sleeve, a fixing screw and an adjusting screw. The laser module is fixedly connected to the top of the supporting base plate or the bottom of the target plate through a plurality of the fixing screws and a plurality of the adjusting screws. The laser is fixedly installed inside the laser sleeve. The laser beam emitted by the laser emission reference device and the array light spot characteristic target component is calibrated in advance and defined as a spatial straight line by fitting.

5. A high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism according to claim 4, characterized in that: The feature detection and recognition component includes: Support frame; A camera detector is arranged on the top of the support frame, and the top of the support frame is detachably connected to the camera detector. An optical lens is arranged at the shooting end of the camera detector, and the field of view of the optical lens can cover the target plate characteristic information of the array light spot characteristic target component, as well as the light spot where the laser emitted by the laser emission reference intersects with the target plate, and the light spot where the laser emitted by the array light spot characteristic target component itself intersects with the target plate through the light beam reflected by the reflector.

6. A high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism according to claim 5, characterized in that: The laser emission reference device has at least three laser beams that irradiate the planar area at the bottom of the target plate in different positions and form at least three complete laser spots, and the centroids of the three intersecting laser spots are not collinear.

7. A high-precision measurement method for the position and posture of a six-degree-of-freedom parallel mechanism, characterized in that: A high-precision position and posture measurement system for a six-degree-of-freedom parallel mechanism as described in any one of claims 1 to 6, comprising the following steps: Step 1: First calibrate and fit the three-dimensional coordinate equation of the laser beam space. At least three groups of laser emission units emit three laser beams through the laser. The equivalent linear equation of the emitted laser beam is as follows: L1:xj1=Xj10+tj1*Xj1; yj1=Yj10+tj1*Yj1; zj1=Zj10+tj1*Zj1; L2:xj2=Xj20+tj2*Xj2; yj2=Yj20+tj2*Yj2; zj2=Zj20+tj2*Zj2; L3:xj3=Xj30+tj3*Xj3; yj3=Yj30+tj3*Yj3; zj3=Zj30+tj3*Zj3; In the above formula: L1, L2, L3 are the equivalent spatial straight line equations of the three laser beams emitted by the three lasers; (xj1, yj1, zj1) are the coordinates of any point on the laser beam spatial straight line L1 in space; (xj2, yj2, zj2) are the coordinates of any point on the laser beam spatial straight line L2 in space; (xj3, yj3, zj3) are the coordinates of any point of the laser beam spatial straight line L3 in space; Xj10, Yj10, Zj10, Xj1, Yj1, Zj1, Xj20, Yj20, Zj20, Xj2, Yj2, Zj2, Xj30, Yj30, Zj30, Xj3, Yj3, Zj3 are the constants of the straight line equation; tj1, tj2, tj3 are the variable parameters of the straight line equation; Step 2: Pre-identify or calibrate the characteristic edge or characteristic point of a specific plane area of ​​the target to be measured, and obtain the relative position relationship of the edge or characteristic point; the characteristic point is any position of the plane area to be measured; Step 3: Using the relative position relationship of the plane corner points or edge features calibrated in step 2, the feature detection and recognition component directly photographs the target plane to be measured, and calibrates the camera intrinsic parameters and the camera optical system distortion parameters using the known corner point and edge feature position relationship and the two-dimensional image captured by the camera; Steps to solve detector distortion based on the double straight line principle: 1) Define camera lens distortion as: Where: (x u ,y u ) is the undistorted image point; (x d ,y d ) is the corresponding distorted image point; λ1 and λ2 are the distortion coefficients; (C x , C y ) is the distortion centre; 2) Define the ideal straight line equation of any straight line on the object to be measured in the image as: ax u +by u +c=0 a, b, c are the parameters of the straight line equation; 3) Combining steps 1-2, we get: In the formula, 4) Use the feature detection and recognition component to extract the edge curve (distorted straight line) corresponding to the ideal straight line on the target image. For any edge curve, (x d,i ,y d,i ), i=1,2,…,n is any point on the edge, satisfying the formula in step 3, we can get: 5) Using the least square method to solve the distortion coefficients e, f and g in step 4, and using the obtained distortion coefficients to perform distortion correction on the image; Step 4: Define a two-dimensional coordinate system using the plane image of the target plate obtained by the feature detection and recognition component, select the intersection formed by the two edges of the specific plane as the two-dimensional coordinate origin, and define the straight line formed by one edge as the X-axis, draw a perpendicular line to the defined X-axis as the Y-axis of the two-dimensional coordinate system, and determine another edge point as the next straight line of the two-dimensional coordinate system, and use this two-dimensional coordinate system to define the two-dimensional position information of the remaining feature points respectively, and the definition of the subsequent measurement quasi-coordinate system remains unchanged. If a two-dimensional coordinate system is defined for a plane feature point, select two feature points, one point is defined as the two-dimensional coordinate origin, and the connecting line is used as the X-axis. Draw a perpendicular line to the defined X-axis as the Y-axis of the two-dimensional coordinate system, and determine the coordinates of the third feature point of the three feature points in the two-dimensional coordinate system; Step 5: Under the two-dimensional coordinate system established in step 4, using image processing technology, according to the image obtained by the feature detection and recognition component, determine the location of the centroid of the spot formed by the intersection of the three laser beams emitted by the laser on the plane area of ​​the target to be measured. The two-dimensional coordinates based on the target board system coordinate system are recorded as: P01:(x01,y01), P02:(x02,y02), P03:(x03,y03); Step 6: Using the equivalent space straight line equation established in step 1 and the position coordinates obtained in step 5, and the principle that the lengths of the same space line segments are equal in coordinate systems with different proportional factors, calculate the spatial coordinates of the center of mass of the light spots where the laser beams emitted by the three lasers intersect the plane area of ​​the target to be measured. The spatial coordinates are defined as the spatial coordinates of the center of mass of the three light spots of the target to be measured, which are recorded as: Pq01: (xq01, yq01, zq01), Pq02: (xq02, yq02, zq02), Pq03: (xq03, yq03, zq03); The specific calculation process is as follows: According to the principle of equal length of space line segments: (xq01-xq02)^2+(yq01-yq02)^2+(zq01-zq02)^2=(x02-x01)^2+(y02-y01)^2; (xq03-xq02)^2+(yq03-yq02)^2+(zq03-zq02)^2=(x02-x03)^2+(y02-y03)^2; (xq03-xq01)^2+(yq03-yq01)^2+(zq03-zq01)^2=(x01-x03)^2+(y01-y03)^2; Combined with the three laser fitting space straight line equations, the spatial coordinates of any three points in the plane area of ​​the target to be measured based on the laser emission reference coordinate system can be calculated, Pq01: (xq01, yq01, zq01), Pq02: (xq02, yq02, zq02), Pq03: (xq03, yq03, zq03); Step 8: The coordinates of the three light spots in the target board coordinate system are P01: (x01, y01, 0), P02: (x02, y02, 0), and P03: (x03, y03, 0). Using the BURSA principle, the coordinates of the common points in the two coordinate systems can be solved to obtain the position translation and attitude deviation in the two coordinate systems. Where (X Ti ,Y Ti ,Z Ti ) are the three-dimensional coordinates of the three light spots in the laser emission reference coordinate system, (X i ,Y i ,Z i ) is the three-dimensional coordinate based on the target board system coordinate system (defined as Z i =0); (ΔX, ΔY, ΔZ) are the position translations of the launch and target coordinate systems, k is the calculation scale factor of the two coordinate systems, (ε X ,ε Y ,ε Z ) is the attitude deviation angle of the launch and target coordinate systems; Step 9: Repeat steps 3-8, and use the position translation and attitude deviation angle of the target board coordinate system relative to the launch reference coordinate system solved under different attitudes to obtain the target's 3-DOF position information and 3-DOF attitude information; Step 10: Define an edge of the target board as the X-axis of the target board system coordinate system, define the corner point of this edge and the adjacent edge as the origin, take the plane of the target board as the XOY plane, and the direction perpendicular to the plane of the target board as the Z-axis to establish the target board system coordinate system; Step 11: Define the laser beams emitted by the three lasers on the target board system as L5, L6, and L7; Step 12: Taking laser beam L5 as an example, the rotation matrix R and translation matrix T between the target board system coordinate system and the laser emission system coordinate system are obtained by the three-dimensional structured light method to solve the spatial straight line equation of laser beam L5 in the laser emission system coordinate system: The conversion relationship between the target board coordinate system and the laser launch system coordinate system is as follows: in, Represents the coordinates in the target board coordinate system, Represents the coordinates in the laser launch system coordinate system; R is a 3×3 rotation matrix, which describes the rotation relationship between the target board coordinate system and the laser emission system coordinate system: T is the translation vector, which describes the translation relationship from the target board coordinate system to the laser emission system coordinate system: The spatial straight line equation L5 of the laser beam in the target plate coordinate system is defined as follows: X1=a1s1+b1 Y1=c1s1+d1 Z1=s1 The conversion of L5 in the target board coordinate system to the laser launch system coordinate system is as follows: The three coordinate components are: X2=(r 11 a1+r 12 c1+r 13 )S1+(r 11 b1+r 12 d1+t1), Y2=(r 21 a1+r 22 c1+r 23 )S1+(r 21 b1+r 22 d1+t2), Z2=(r 31 a1+r 32 c1+r 33 )S1+(r 31 b1+r 32 d1+p3). The equation of the laser beam L5 in the laser emission system coordinate system is solved as follows: X2=A2S1+B2, Y2=C2S1+D2, Z2=E2S1+F2. in, A2=r 11 a1+r 12 c1+r 13 ,B2=r 11 b1+r 12 d1+t1, C2=r 21 a1+T 22 c1+T 23 ,D2=r 21 b1+r 22 d1+t2, E2=r 31 a1+r 32 c1+T 33 ,F2=r 31 b1+r 32 d1+t3. Step 13: Define the reflector plane as the plane with Z=0 in the laser emission system coordinate system, then the equation of the spatial straight line after the laser beam L5 is reflected by the reflector is L′5: X′2=X2=A2S1+B2, Y′2=Y2=C2S1+D2, Z′2=-Z2=-(E2S1+F2). Step 14: Use the three-dimensional structured light method to solve the equation of the target plate plane in the laser emission system coordinate system. The target plate plane M1 is: M1: A3x+B3y+C3z+D3=0 Step 15: Calculate the intersection coordinates P5 (x5, y5, Z5) of the laser beam L′5 after being reflected by the reflector and the target plate plane M1; Among them, the intersection point P5 (x5, y5, z5) satisfies the spatial straight line equation of the laser beam L′5, x5=X2′=A2S1+B2, y5=Y2′=C2S1+D2 z5=Z2′=-(E2S1+F2). Substitute x5, y5, z5 into the target plate plane equation A3x+B3y+C3z+D3=0: A3(A2S1+B2)+B3(C2S1+D2)+C3(-(E2S1+F2))+D3=0 After expansion: (A3A2+B3C2-C3E2)S1+(A3B2+B3D2-C3F2+D3)=0 After solving the parameter S1, substitute it into the intersection coordinate formula to get the intersection coordinates: in: k1=A3A2+B3C2-C3E2, k2=A3B2+B3D2-C3F2+D3. Step 16: Using the stereo structured light method, the position change of the target plate under the laser emission system is solved as Δx, Δy, Δz, α, β, γ; Step 17: According to the pose change in step 16, Δx, Δy, Δz, α, β, γ, the rotation matrix R and translation matrix T′ representing the pose change of the target board system in the laser emission system coordinate system are: in: Step 18: According to the rotation matrix R′ and the translation matrix T′ obtained in step 17, the spatial straight line equation L″5 of the laser beam L5 after the posture transformation is calculated: Substitute the linear equation (X2, Y2, Z2) of the laser beam L5 into the rotation and translation formula: The linear equation L″5 of the laser beam space after the posture transformation is: X3=A3S1+B3, Y3=C3S1+D3, Z3=E3S1+F3 in: A3=r 11 A2+r 12 C2+r 13 E2,B3=r11B2+r 12 D2+r 13 F2+Δx C3=r 21 A2+r 22 C2+r 23 E2,D3=r 21 B2+r 22 D2+r 23 F2+Δy E3=r 31 A2+r 32 C2+r 33 E2,F3=r 31 B2+r 32 D2+r 33 F2+Δz Step 19: The spatial straight line equation of the laser beam L″5 after being reflected by the reflector becomes L″′5: X3=A3S1+B3, Y3=C3S1+D3, Z3=-E3S1-F3 Step 20: After the target plate plane changes its posture, the plane equation of the target plate plane M1 in the laser emission system coordinate system becomes: M′1:A3′x+B3′y+C3′z+D3′=0 Like: D3′=D3-(A3′Δx+B3′Δy+C3′Δz) Step 21: Solve the intersection coordinates P′5 (x′5, y′5, z′5) of the laser beam L″′5 and the plane M′1 as follows: in: K1′=A3′A3+B3′C3-C3′E3, K2′=A3′B3+B3′D3-C3′F3+D3′ Step 22: According to the camera detector, it is solved that the distance between the laser beam and the light spot on the target plate plane after the posture change occurs is ΔL1; Step 23: Combine steps 16 and 21 to obtain the intersection coordinates P5 (x5, y5, z5) and P′5 (x′5, y′5, z′5) before and after the posture change and the distance ΔL1 in step 23, and we can get: The relationship can be written as: The above relationship can be written as follows: F1(α, β, γ) = 0 Step 24: Repeat steps 12-23 to obtain the equations of laser beams L6, L7 and ΔL2, ΔL3 with respect to α, β, γ: F2(α, β, γ) = 0 F3(α, β, γ) = 0 Step 25: Transform the equations in steps 23-24 into: F(α,β,γ)=F1+F2+F3=0 Step 26: The angles α, β, and γ can be solved by using the Gauss-Newton nonlinear least squares algorithm; finally, the position information of the array spot feature target component relative to the laser emission reference device is obtained; Step 27: Repeat steps 3-26, and use the position translation and attitude deviation angle of the target plate coordinate system relative to the launch reference coordinate system solved under different postures to obtain the 3-DOF position information and 3-DOF attitude information of the target, and feed back the 6-DOF array spot feature target component posture information, i.e. the parallel mechanism moving platform posture information, to the 6-DOF parallel mechanism structure in real time for motion adjustment; Step 28: Measure the posture information and convert it into the posture adjustment information of the six-degree-of-freedom parallel mechanism structure: The parallel mechanism base coordinate system {B} is located on the parallel mechanism fixed platform. The parallel mechanism base coordinate system {B} is the reference datum of other coordinate systems. The moving platform coordinate system {P} is located on the parallel mechanism moving platform. {M} is the laser emission reference coordinate system of the measurement system. {T} is the target plate coordinate system. The relative position of the target plate coordinate system and the moving platform coordinate system is fixed. The transformation relationship between coordinate systems is represented by the homogeneous transformation matrix. The posture transformation relationship from the moving platform coordinate system {P} to the base coordinate system {B} is expressed by To express, similarly, the pose transformation from the target board coordinate system {T} to the base coordinate system {B} is expressed as The pose transformation from the target plate coordinate system {T} to the moving platform coordinate system {P} is expressed as Indicates that the pose transformation matrix is: The above coordinate system transformation relationship satisfies: Combined with the pose transformation matrix, it can be expressed as: From formula 2, we can get: Similarly, in the laser emission reference coordinate system, (5) and (6) can be expressed as Combining equations (5)-(8), we can obtain the rotation matrix and translation matrix of the six-degree-of-freedom parallel mechanism structure: The measured posture information can be converted into the posture information of the six-degree-of-freedom parallel mechanism structure through equations (9) and (10), where and is the rotation matrix and translation matrix calculated from the 3-DOF posture information and 3-DOF position information obtained in step 27, is a fixed value and can be obtained based on the measurement results of multiple pose points.

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