A device and method for measuring the spatial pose guidance accuracy of a robot vision system

Abstract

This invention discloses a device and method for measuring the spatial pose guidance accuracy of a robot vision system, relating to the field of robot guidance technology. The device includes a calibration flange mounted on a multi-degree-of-freedom motion platform. Three identical cylinders—a first cylinder, a second cylinder, and a third cylinder—are arranged on the end face of the calibration flange. The laser tracker and vision system can easily fit and identify the characteristic centers of the three cylinder end face circles on the calibration flange. Based on the identified end face circle features, the vision system guides the end effector of a robot tool to the corresponding position. The laser tracker measures the actual pose of the robot tool end effector after guidance, thus accurately measuring the spatial pose guidance accuracy of the robot vision system.

Description

Technical Field

[0001] This invention relates to the field of robot guidance technology, specifically to a device and method for measuring the accuracy of spatial pose guidance in a robot vision system. Background Technology

[0002] Robots are essential production equipment in industrial fields such as aviation, aerospace, defense, and machinery manufacturing. The integration and application of robot systems are moving towards intelligentization, which is often reflected in the integration of high-precision vision systems at the robot's end effector. After integrating the vision system, the vision system typically establishes a corresponding pose matrix relationship with the robot's base coordinate system and the tool coordinate system. The calibration of the robot's vision system with the tool coordinate system (commonly known as "hand-eye" calibration) is a crucial step for the robot to guide the end effector to complete tasks. The accuracy of this "hand-eye" calibration determines whether the vision system can accurately guide the robot's spatial pose.

[0003] Currently, there are no relevant testing standards or methods for the spatial pose guidance accuracy of robot vision systems. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide a device and method for measuring the spatial pose guidance accuracy of a robot vision system, so as to accurately measure the spatial pose guidance accuracy of the robot vision system.

[0005] This invention is achieved through the following technical solution:

[0006] A device for measuring the spatial pose guidance accuracy of a robot vision system includes:

[0007] The calibration flange is installed on the multi-degree-of-freedom motion platform device. Three cylinders of the same size, namely a first cylinder, a second cylinder, and a third cylinder, are provided on the end face of the calibration flange. The first cylinder, the second cylinder, and the third cylinder are arranged in a right-angled triangle, and the thickness of the three cylinders is the same as the radius of the target ball.

[0008] The magnetic target holder fixture is located at the end of the robot flange. The magnetic target holder fixture includes four target holders for mounting target balls: a first target holder, a second target holder, a third target holder, and a fourth target holder. The four target holders are arranged in a rectangular shape, with the first and fourth target holders arranged diagonally, and the second and third target holders arranged diagonally.

[0009] Further solutions:

[0010] The present invention also provides a measurement method for a robot vision system spatial pose guidance accuracy measurement device, comprising the following steps:

[0011] S1: Install a magnetic target holder fixture at the end of the robot flange, adsorb the target ball onto the first target holder, and establish a coordinate system {F} that coincides with the robot flange coordinate system in the laser tracking measurement system;

[0012] S2: Install target balls on the second and third target mounts respectively. Measure the coordinates of the three target balls in a fixed order using a laser tracker. Construct a direction vector based on the coordinate values ​​of the three target balls. Establish a coordinate system {T} in the laser tracking measurement system, with the coordinates of the target ball in the first target mount as the origin. The coordinate system is then established based on the homogeneous matrix relationship between coordinate system {F} and coordinate system {T} in the tracker measurement system. The pose relationship between the robot tool coordinate system and the flange coordinate system is obtained by reverse calculation, and the pose calibration of the robot end tool is completed.

[0013] S3: Align the laser tracking measurement coordinate system {B} with the robot base coordinate system {base};

[0014] S4: Fix the calibration flange at position A, and in coordinate system {B}, move the target ball to several positions close to the outer circles of the first cylinder, the second cylinder and the third cylinder respectively. Collect the point coordinates of each position through the laser tracker, and fit the end face circle and the center of the first cylinder, the second cylinder and the third cylinder respectively.

[0015] S5: In the laser tracker measurement system, a direction vector is constructed based on the coordinate values ​​of the center of the end faces of the first, second, and third cylinders. A coordinate system {W} is established with the center of the end face of the first cylinder (located at the right-angle endpoint) as the origin. The homogeneous matrix relationship between coordinate systems {B} and {W} in the tracker measurement system is then established. The pose value of the calibration flange in the robot base coordinate system {base} is calculated, and this pose value is the theoretical value for guidance by the robot vision system.

[0016] S6: The robot vision system identifies the end face circular features of the first, second, and third cylinders of the calibration flange at position A. The vision system uses the three identified end face center points to establish a vision system coordinate system {S} that is consistent with the pose of the coordinate system {W} of the tracker measurement system.

[0017] S7: Subsequently, the calibration flange is moved to position C. The robot vision system guides the three target balls at the end of the robot tool to the corresponding positions of the first, second, and third cylinders. The coordinates of the three target balls at this time are measured by the laser tracker. A coordinate system {W1} is established using the coordinates of the three target balls at this time. The homogeneous matrix relationship between the coordinate system {W1} and the coordinate system {B} in the laser tracking measurement system is then established. The pose values ​​of coordinate system {W1} and coordinate system {B} are obtained by calculation. These pose values ​​are the measured values ​​guided by the robot vision system. The calibration flange is then moved back to the fixed position A.

[0018] S8: Based on the theoretical values ​​before robot vision system guidance and the measured values ​​after robot vision system guidance, obtain the spatial pose guidance accuracy of robot vision system.

[0019] In a further embodiment, in step S1, the specific steps for adsorbing the target ball onto the first target holder and establishing a coordinate system {F} that coincides with the robot flange coordinate system in the laser tracking measurement system are as follows:

[0020] S11: Adhere the target ball to the first target holder, and record the robot's pose P1; the robot orbits the flange coordinate system X around the default flange coordinate system origin. F Y F Z F The robot undergoes constant-angle attitude transformations along the axis. The laser tracker acquires the spatial coordinates of the target sphere at each robot's position within the flange coordinate system. F Y F Z F By fitting all spatial points measured by axis rotation, a spatial sphere is obtained, and the circles and their planes rotating around Rx, Ry, and Rz are fitted. The normal vectors of the circles and their planes rotating around Rx, Ry, and Rz are then constructed. Find the angle between any two normal vectors.

[0021] S12: The robot returns to pose P1, with The two normal vectors that are closest to 90° between the three vectors are used as the reference axes, and a coordinate system {F} is established with the center of the sphere as the origin using the right-hand rule; at this time, the coordinate system {F} based on laser tracking coincides precisely with the robot flange coordinate system.

[0022] In a further step, in step S11, when solving for the angle between any two normal vectors, if θ XY θ YZ θ XZ If any one of the included angles is within the range of 90°±0.03°, then stop step S11. If none of the three included angles are within the range of 90°±0.03°, then repeat step S11.

[0023] In a further embodiment, step S2 also includes the following specific steps:

[0024] Target balls were installed on the second and third target mounts, respectively. The coordinates of the three target balls were measured in a fixed order using a laser tracker. The measured coordinates of the target ball in the first target mount were b1(X). b1 ,Y b1 Zb1 The target ball coordinates in the second target are b2(X). b2 ,Y b2 Z b2 The target sphere in the third target position has coordinates b3(X). b3 ,Y b3 Z b3 );

[0025] Using the target ball coordinates b1(X) in the first target position b1 ,Y b1 Z b1 () as the origin, with For X T positive direction, Cross product coordinate system Z T The positive direction is used to determine the coordinate system Y according to the right-hand rule. T The positive direction is determined to establish the robot's tool coordinate system {T}. The homogeneous matrix relationship between coordinate system {F} and coordinate system {T} in the system is then measured using a tracker. The pose relationship (X,Y,Z,A,B,C) between the robot tool coordinate system {T} and the flange coordinate system can be calculated in reverse. The calculated pose relationship is then imported into the robot controller to complete the pose calibration of the robot end tool.

[0026] In a further embodiment, step S3 also includes the following specific steps:

[0027] S31: Within its maximum reachable motion space, the robot controls the target ball in the first target mount at the robot's end effector to move M positions in space, where M > 4, and the M positions are not on the same plane. The robot also records the coordinates (X, Y, X, Y) of the M positions on the robot's teach pendant. R1 Y R1 Z R1 ), (X R2 Y R2 Z R2 ...(X) RM Y RM Z RM The laser tracker collects the coordinate values ​​of the target ball at M positions of the robot's end effector (X). V1 Y V1 Z V1 ), (X V2 Y V2 Z V2 ...(X) VM Y VM Z VM );

[0028] S32: Given the coordinates of the center of the same target ball in the robot's base coordinate system and the coordinates of the laser tracker's measurement coordinate system, the pose relationship between the laser tracker's measurement coordinate system and the robot's base coordinate system can be solved. Based on the pose relationship between the two coordinate systems, the laser tracking measurement coordinate system {B} is made to coincide with the robot's base coordinate system {base}.

[0029] In a further embodiment, step S5 also includes the following specific steps:

[0030] S51: In the laser tracker measurement system, the coordinates of the center points of the end faces of three cylinders are used, where the coordinates of the center points of the end faces of the first, second, and third cylinders are FL2(X). L2 Y L2 Z L2 ), FL3(X L3 Y L3 Z L3 ), FL4(X L4 Y L4 Z L4 Construct direction vectors respectively. Cross product Construct a normal vector, take the center point of the first cylindrical end face as the origin of the coordinate system, and establish a calibration coordinate system {W} on the calibration flange using the right-hand rule;

[0031] S52: In the laser tracker measurement system, given both a coordinate system {B} coinciding with the robot base coordinate system {base} and a calibration flange coordinate system {W}, the homogeneous matrix relationship between the two in the laser tracker measurement system can be used to determine the coordinate system's coordinate system. The pose value of the calibration flange in the robot base coordinate system is calculated. This pose value is the theoretical value (Xc, Yc, Zc, ac, bc, cc) for guidance by the robot vision system.

[0032] In a further step, after obtaining the actual spatial pose value guided by the first robot vision system in step S7, the following steps are also included:

[0033] Repeat steps S6-S7 a total of n (n≥10) times. Through n recognitions and guidance of the robot's end-effector target ball to position A on the calibration flange by the robot vision system, and n measurements of the actual pose of the robot's end-effector target ball by the tracker, the pose result (X) guided by the robot vision system n times can be measured and calculated. i Y i Z i a i b i c i Where i = 1, 2, 3, ..., n.

[0034] A further refinement is that the spatial pose guidance accuracy of the robot vision system includes the position accuracy, attitude accuracy, position repeatability, and attitude repeatability of the robot vision system spatial pose guidance.

[0035] A further advanced solution is to improve the positional accuracy (AP) of the robot vision system after n guidance cycles. P The calculation formula is:

[0036]

[0037] in

[0038]

[0039] attitude accuracy

[0040] in

[0041]

[0042] Positional repeatability

[0043] in

[0044]

[0045] Posture repeatability

[0046] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0047] The present invention provides a device and method for measuring the spatial pose guidance accuracy of a robot vision system. Based on three cylinders of equal diameter and thickness on the end face of a calibration flange, the laser tracker and vision system can conveniently measure, fit, and identify the characteristic center of the three cylinders of equal diameter on the end face of the calibration flange. The robot tool calibration based on three target balls is completed, and the measurement coordinate system {B} of the laser tracker is aligned with the robot base coordinate system {base}. The pose of the calibration flange is measured in coordinate system {B}, thus obtaining the theoretical pose value of the calibration flange relative to the robot. The vision system identifies the calibration flange, and then guides the robot end-effector to the corresponding pose of the calibration flange. The laser tracker measures the actual pose of the robot end-effector target ball tool after the vision system guidance. In the laser tracking measurement system, the theoretical pose of the calibration flange relative to the robot base coordinate system before guidance and the actual pose of the robot end-effector after the vision system guidance are obtained simultaneously, thus yielding the position and attitude deviation between the theoretical pose and the actual pose. Through multiple identifications and guidances by the robot vision system, and measurements by the laser tracker, the position accuracy deviation, position repeatability deviation, attitude accuracy deviation, and attitude repeatability deviation of the robot vision system's spatial pose guidance accuracy are obtained. Attached Figure Description

[0048] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0049] Figure 1 This is a schematic diagram of the calibration flange provided by the present invention;

[0050] Figure 2 This is a schematic diagram of the structure of the magnetic target holder tooling provided by the present invention;

[0051] Figure 3 This is a schematic diagram of the measurement layout provided by the present invention.

[0052] The attached diagram shows the markings and corresponding component names:

[0053] 1-Calibration flange, 2-First cylinder, 3-Second cylinder, 4-Third cylinder, 5-Magnetic target holder fixture, 51-First target holder, 52-Second target holder, 53-Third target holder. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0055] Example 1:

[0056] This embodiment 1 provides a device for measuring the spatial pose guidance accuracy of a robot vision system, such as... Figures 1-3 As shown, it includes: a calibration flange 1 disposed on a multi-degree-of-freedom motion platform device, wherein three identical cylinders 2, 3, and 4 are disposed on the end face of the calibration flange 1, the first cylinder 2, the second cylinder 3, and the third cylinder 4 are arranged in a right-angled triangle, and their thickness is the same as the radius of the target ball; and a magnetic target holder fixture 5 disposed at the end of the robot flange, wherein the magnetic target holder fixture 5 includes four target holders 51, 52, 53, and 54 for mounting the target ball, the four target holders are arranged in a rectangular shape, and the first target holder 51 and the fourth target holder are arranged diagonally, and the second target holder 52 and the third target holder 53 are arranged diagonally.

[0057] In the above-mentioned device, the calibration flange 1 and its three cylindrical structures of equal diameter fixed to the end face are as follows: Figure 1 The rectangular four-target fixture and target ball installation diagram are shown below. Figure 2 As shown, the rectangular four-target fixture is installed at the end of the robot tool, and the calibration flange 1 is installed on the two-degree-of-freedom motion platform. The layout of the robot system, laser tracker, and pose calibration device throughout the measurement process is as follows: Figure 3 As shown.

[0058] The two-degree-of-freedom motion platform consists of two linear motion axes, each with a forward / backward travel of 600 mm and a vertical travel of 800 mm. The repeatability of each linear axis is better than 2 μm. Calibration flange 1 is mounted on the worktable of the two-degree-of-freedom motion platform's forward / backward motion axes. The two-degree-of-freedom platform can move calibration flange 1 to different positions in space, allowing the robot's vision system to identify and guide it, thus measuring and verifying the pose guidance accuracy of the robot at different spatial positions. Three cylinders of equal diameter are fixed to the end face of calibration flange 1, and these cylinders are arranged at right angles. The thickness D of the three cylinders of equal diameter and thickness is equal to the radius R of the target ball measured by the laser tracker. 靶 Equal (D=R) 靶 The flatness of the calibrated flange 1 is better than 2μm, the cylindricity of the three equal diameter cylinders is better than 1μm, the flatness of the end face of the three equal diameter cylinders is better than 1μm, the dimensional accuracy of the three equal diameter cylinders is better than 2μm, and the positional accuracy of the three equal diameter cylinders is better than 2μm.

[0059] Example 2:

[0060] This embodiment 2 further optimizes the first embodiment and provides a measurement method for a robot vision system spatial pose guidance accuracy measurement device, including the following specific steps:

[0061] 1. The robot moves to a suitable position, and four rectangularly distributed magnetic target holders 5 are installed onto the end of the robot flange. The target ball is attracted to the first target holder 51 of the fixture, and the robot pose P1 is recorded during teaching. The robot then orbits the flange coordinate system X around the default TCP (origin of the flange coordinate system). F Y F Z F The robot undergoes constant-angle attitude transformations along the axis. A laser tracker acquires the spatial coordinates of the target ball at each robot's position within the flange coordinate system. F Y F Z F All spatial points measured by axis rotation are fitted to obtain a spatial sphere, and the circles and their planes that rotate around Rx, Ry, and Rz are also fitted.

[0062] The equations for a space sphere are as follows: (xa) 2 +(yb) 2 +(zc) 2 =R 2 (1)

[0063] The equation is transformed as follows: 2ax + 2by + 2cz - a 2 -b 2 -c 2 +R 2 =x 2 +y 2 +z 2 (2)

[0064] Let 2a = A, 2b = B, 2c = C, and a. 2 +b 2 +c 2 -R 2 =D;

[0065] The above equation can be written in matrix form as follows:

[0066]

[0067] The matrix is ​​transformed as follows:

[0068]

[0069] Solving equation (4) yields A, B, C, and D. Substituting these values ​​into equation (4), we get a = A / 2, b = B / 2, and c = C / 2. This gives us the coordinates of the sphere's center, Qo(a,b,c), and the sphere's radius, R.

[0070] Space plane fitting:

[0071] The equation of the spatial plane can be expressed as: A1x + B1y + C1z + 1 = 0, (5)

[0072] The equation can be expressed in matrix form as follows:

[0073]

[0074] After matrix transformation, the following equation can be obtained:

[0075]

[0076] Solving for the coefficients A1, B1, and C1 yields the equation of the spatial plane. By combining this spatial plane equation (5) with the sphere equation (1) obtained in the previous step, the coordinates of the spatial center Ca(a1,b1,c1) and the radius r can be obtained.

[0077] Construct the normal vectors of the circle and its plane that rotate around Rx, Ry, and Rz. Solve for the angles between the normal vectors. If θ XY θ YZ θ XZ If any one of the included angles is within the range of 90°±0.03°, stop the above operation process. If none of the three included angles are within the range of 90°±0.03°, repeat the above operation process.

[0078] 2. The robot returns to pose P1, with... The two normal vectors that are closest to 90° between the three vectors are used as the reference axes, and a coordinate system {F} is established with the center of the sphere as the origin using the right-hand rule; at this time, the coordinate system {F} based on laser tracking coincides precisely with the robot flange coordinate system.

[0079] 3. Target balls are installed on the second target seat 52 and the third target seat 53 of the robot end effector magnetic target holder 5, respectively. The three target balls adsorbed on the first target seat 51, the second target seat 52, and the third target seat 53 are arranged in a right-angled triangle. The coordinates b1(X) of the target ball on the first target seat 51 are measured in a fixed order in the coordinate system {F} of the laser tracker. b1 ,Y b1 Z b1 ), the target ball coordinates b2(X) on the second target mount 52 b2 ,Y b2 Z b2 ), the target ball coordinates b3(X) on the third target 53 b3 ,Y b3 Z b3 ), with b1(X b1 ,Y b1Z b1 () as the origin, with For X T positive direction, Cross product coordinate system Z T The positive direction is used to determine the coordinate system Y according to the right-hand rule. T The positive direction is determined to establish the robot's tool coordinate system {T}. The homogeneous matrix relationship between coordinate system {F} and coordinate system {T} in the system is then measured using a tracker. The pose relationship (X,Y,Z,A,B,C) between the robot tool coordinate system {T} and the flange coordinate system can be calculated in reverse. The calculated pose relationship is then imported into the robot controller to complete the pose calibration of the robot end tool.

[0080] 4. Within its maximum reachable motion space, the robot controls the target ball (TCP) on the first target mount 51 at the robot's end effector to move M positions (M>4) within the space, and the M positions are not on the same plane. The robot also records the coordinates (X, Y, X, Y) of the M positions on the robot's teach pendant. R1 Y R1 Z R1 ), (X R2 Y R2 Z R2 ...(X) RM Y RM Z RM The laser tracker collects the coordinate values ​​of the target ball at M positions of the robot's end effector (X). V1 Y V1 Z V1 ), (X V2 Y V2 Z V2 ...(X) VM Y VM Z VM ).

[0081] 5. With the coordinates of the center of the same target ball in the robot's base coordinate system and the coordinates of the laser tracker's measurement coordinate system, the pose relationship between the laser tracker's measurement coordinate system and the robot's base coordinate system can be solved. Based on the pose relationship between the two coordinate systems, the laser tracking measurement coordinate system {B} is made to coincide with the robot's base coordinate system {base}.

[0082] 6. Install calibration flange 1 onto a two-degree-of-freedom motion platform. Control the two-degree-of-freedom motion platform to move calibration flange 1 to a fixed position A. In the coordinate system {B} of the laser tracker, move the target ball several times, keeping it close to the outer circles of the first cylinder 2, the second cylinder 3, and the third cylinder 4 on calibration flange 1. The laser tracker collects the coordinates of each position. When the target ball moves on the first cylinder 2, the second cylinder 3, and the third cylinder 4 on calibration flange 1, the end face of calibration flange 1 performs axial positioning of the target ball, and the outer circles of the three cylinders perform radial positioning of the target ball. Furthermore, since the thickness D of the three cylinders with equal diameter and thickness is equal to the radius R of the target ball measured by the laser tracker... 靶 Equal (D=R) 靶 It can accurately fit the end face circles of three cylinders and obtain the center coordinates FL2(X) of each circle. L2 Y L2 Z L2 ), FL3(X L3 Y L3 Z L3 ), FL4(X L4 Y L4 Z L4 ).

[0083] 7. In the laser tracker measurement system, construct direction vectors using the coordinates of the centers of the three cylindrical end faces. Cross product Construct a normal vector, and use the center point of the end face of the first cylinder 2 as the origin of the coordinate system. Establish a calibration coordinate system {W} on the calibration flange 1 using the right-hand rule.

[0084] 8. In the laser tracker measurement system, there is a coordinate system {B} that coincides with the robot base coordinate system {base}, and a coordinate system {W} based on calibration flange 1. The homogeneous matrix relationship between these two systems can be determined through the laser tracker measurement system. The pose relationship of the calibration flange 1 in the robot base coordinate system is calculated. This pose value is the theoretical value (Xc, Yc, Zc, ac, bc, cc) for the robot vision system guidance.

[0085] 9. The mobile robot positions the robot vision system at the optimal recognition distance from the three cylindrical end faces on the calibration flange 1, and teaches and records the robot's current pose P2. The robot vision system identifies the circular features of the three cylindrical end faces on the calibration flange 1. Using the center points of the three identified end faces, the vision system establishes a coordinate system {S} that is consistent with the pose of the coordinate system {W} of the tracking measurement system.

[0086] 10. Control the two-degree-of-freedom motion platform to move the calibration flange 1 to a fixed position C. Use the control program to guide the robot's end effector, the three target balls, to their corresponding positions on the first cylinder 2, the second cylinder 3, and the third cylinder 4 on the calibration flange 1. The laser tracker measures the positions of the three target balls at this time and establishes a coordinate system {W1} using the coordinates of the three target balls. At this point, the homogeneous matrix relationship between coordinate system {W1} and coordinate system {B} can be obtained in the laser tracking measurement system. The pose relationship between coordinate system {W1} and coordinate system {B} is calculated. This pose value is the measured value (X1, Y1, Z1, a1, b1, c1) guided by the robot vision system.

[0087] 11. After the measurement is completed, the robot moves to pose P2 and then controls the two-degree-of-freedom motion platform to move the calibration flange 1 to the fixed position A.

[0088] 12. By repeating steps 9-11 a total of n (n≥10) times, the robot vision system identifies and guides its end-effector target ball to the fixed position A of the calibration flange 1 n times. The tracker also measures the actual pose of the robot tool end-effector target ball n times. The pose result (X) of the robot vision system's n guidances can then be measured and calculated. i Y i Z i a i b i c i Where i = 1, 2, 3...n, the tracking measurement system simultaneously provides the theoretical values ​​(Xc, Yc, Zc, ac, bc, cc) guided by the robot vision system and the measured values ​​(Xc, Yc, Zc, ac, bc, cc) from n pose measurements. i Y i Z i a i b i c i This allows us to calculate the positional accuracy (AP) of the robot's vision system after n guidance attempts. P ),Right now

[0089] in

[0090]

[0091] attitude accuracy

[0092] in

[0093]

[0094] Positional repeatability

[0095] in

[0096]

[0097] Posture repeatability

[0098] 13. Using a two-degree-of-freedom motion platform, the calibration flange 1 is moved to other fixed poses (D, E, F...) in the robot's reachable space. The robot performs identification and guidance according to the above steps. The laser tracker measures the pose after the robot's vision system guides it, and can measure the guidance accuracy of the robot in any spatial pose within its reachable motion space.

[0099] In summary, by designing and manufacturing the corresponding high-precision calibration flange 1, its laser tracker and vision system can easily fit and identify the characteristic centers of the three cylindrical end faces of equal diameter of the calibration flange 1. The robot tool calibration based on three target balls is completed, and the measurement coordinate system {B} of the laser tracker is aligned with the robot base coordinate system {base}. The pose of the calibration flange is measured in coordinate system {B}, thus obtaining the theoretical pose value of the calibration flange relative to the robot. The vision system identifies the calibration flange, and then guides the robot end-effector to the corresponding pose of the calibration flange. The laser tracker measures the actual pose of the robot end-effector target ball tool after the vision system guidance. In the laser tracking measurement system, the theoretical pose of the calibration flange relative to the robot base coordinate system before guidance and the actual pose of the robot end-effector after the vision system guidance are obtained simultaneously, thus yielding the position and attitude deviation between the theoretical pose and the actual pose. Through multiple identifications and guidances by the robot vision system, and measurements by the laser tracker, the position accuracy deviation, position repeatability deviation, attitude accuracy deviation, and attitude repeatability deviation of the robot vision system's spatial pose guidance accuracy are obtained.

[0100] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A measurement method for a spatial pose guidance accuracy measurement device for a robot vision system, characterized in that, The robot vision system spatial pose guidance accuracy measurement device includes: a calibration flange (1) set on a multi-degree-of-freedom motion platform device, and three first cylinders (2), second cylinders (3) and third cylinders (4) of the same size are provided on the end face of the calibration flange (1). The first cylinders (2), second cylinders (3) and third cylinders (4) are arranged in a right triangle, and the thickness of the three cylinders is the same as the radius of the target ball. The magnetic target holder fixture (5) is located at the end of the robot flange. The magnetic target holder fixture (5) includes four first target holders (51), second target holders (52), third target holders (53) and fourth target holders for mounting target balls. The four target holders are arranged in a rectangular shape, and the first target holder (51) and the fourth target holder are arranged diagonally, and the second target holder (52) and the third target holder (53) are arranged diagonally. The measurement method includes the following steps: S1: Install a magnetic target holder fixture (5) at the end of the robot flange, adsorb the target ball onto the first target holder (51), and establish a coordinate system {F} that coincides with the robot flange coordinate system in the laser tracking measurement system. S2: Install target balls on the second target (52) and the third target (53) respectively. Measure the coordinates of the three target balls in a fixed order using a laser tracker. Construct a direction vector based on the coordinate values ​​of the three target balls. Establish a coordinate system {T} in the laser tracking measurement system with the coordinates of the target ball in the first target (51) as the origin of the coordinate system. Based on the homogeneous matrix relationship between the coordinate system {F} and the coordinate system {T} in the tracker measurement system... The pose relationship between the robot tool coordinate system and the flange coordinate system is obtained by reverse calculation, and the pose calibration of the robot end tool is completed. S3: Align the laser tracking measurement coordinate system {B} with the robot base coordinate system {base}; S4: Fix the calibration flange (1) at position A, and in coordinate system {B}, move the target ball to several positions close to the outer circles of the first cylinder (2), the second cylinder (3) and the third cylinder (4), respectively. Collect the point coordinates of each position through the laser tracker, and fit the end face circle and center of the first cylinder (2), the second cylinder (3) and the third cylinder (4) respectively. S5: In the laser tracker measurement system, a direction vector is constructed based on the coordinate values ​​of the center of the end face of the first cylinder (2), the second cylinder (3), and the third cylinder (4). The center of the end face of the first cylinder (2) located at the right-angle endpoint is taken as the origin of the coordinate system, and a coordinate system {W} is established. The homogeneous matrix relationship between the coordinate system {B} and the coordinate system {W} in the tracker measurement system is used as the basis for this coordinate system. The pose value of the calibration flange (1) in the robot base coordinate system {base} is obtained by calculation. This pose value is the theoretical value for guidance by the robot vision system. S6: The robot vision system identifies the end face circular features of the first cylinder (2), the second cylinder (3) and the third cylinder (4) of the calibration flange (1) at position A. The vision system uses the three identified end face center points to establish a vision system coordinate system {S} that is consistent with the coordinate system {W} of the tracker measurement system. S7: Then, the calibration flange (1) is moved to position C. The robot vision system guides the three target balls at the end of the robot tool to the corresponding positions of the first cylinder (2), the second cylinder (3), and the third cylinder (4). The coordinates of the three target balls at this time are measured by the laser tracker. The coordinate system {W1} is established using the coordinates of the three target balls at this time. The homogeneous matrix relationship between the coordinate system {W1} and the coordinate system {B} in the laser tracking measurement system is then established. The pose values ​​of coordinate system {W1} and coordinate system {B} are obtained by calculation. These pose values ​​are the measured values ​​guided by the robot vision system. The calibration flange is then moved back to the fixed position A. S8: Based on the theoretical values ​​before robot vision system guidance and the measured values ​​after robot vision system guidance, obtain the spatial pose guidance accuracy of robot vision system.

2. The measurement method of the spatial pose guidance accuracy measurement device for a robot vision system according to claim 1, characterized in that, In step S1, the specific steps for adsorbing the target ball onto the first target holder (51) and establishing a coordinate system {F} that coincides with the robot flange coordinate system in the laser tracking measurement system are as follows: S11: Adhere the target ball to the first target holder (51), and teach and record the robot pose P1; The robot revolves around the flange coordinate system X around the default flange coordinate system origin. F Y F Z F The robot undergoes constant-angle attitude transformations along the axis. The laser tracker acquires the spatial coordinates of the target sphere at each robot's position within the flange coordinate system. F Y F Z F By fitting all spatial points measured by axis rotation, a spatial sphere is obtained, and the circles and their planes rotating around Rx, Ry, and Rz are fitted. The normal vectors of the circles and their planes rotating around Rx, Ry, and Rz are then constructed. , , Find the angle between any two normal vectors. S12: The robot returns to pose P1, with , , The two normal vectors that are closest to 90° between the three vectors are used as the reference axes, and a coordinate system {F} is established with the center of the sphere as the origin using the right-hand rule; at this time, the coordinate system {F} based on laser tracking coincides precisely with the robot flange coordinate system.

3. The measurement method of the spatial pose guidance accuracy measurement device for a robot vision system according to claim 2, characterized in that, In step S11, when solving for the angle between any two normal vectors, if If any one of the included angles is within the range of 90°±0.03°, then stop step S11. If none of the three included angles are within the range of 90°±0.03°, then repeat step S11.

4. The measurement method of the spatial pose guidance accuracy measurement device for a robot vision system according to claim 1, characterized in that, Step S2 further includes the following specific steps: Target balls are installed on the second target mount (52) and the third target mount (53), respectively. The coordinates of the three target balls are measured in a fixed order using a laser tracker. The measured coordinates of the target ball in the first target mount (51) are b1(X). b1 , Y b1 Z b1 The target ball coordinates in the second target (52) are b2 (X b2 , Y b2 Z b2 The target ball coordinates in the third target (53) are b3 (X b3 , Y b3 Z b3 ); Using the target ball coordinates b1(X) in the first target position (51) b1 Y b1 Z b1 (with) as the origin, and For X T positive direction, Cross product coordinate system Z T The positive direction is used to determine the coordinate system Y according to the right-hand rule. T The positive direction is determined to establish the robot's tool coordinate system {T}. The homogeneous matrix relationship between coordinate system {F} and coordinate system {T} in the system is measured using a tracker. The pose relationship (X,Y,Z,A,B,C) between the robot tool coordinate system {T} and the flange coordinate system can be calculated in reverse. The calculated pose relationship is then imported into the robot controller to complete the pose calibration of the robot end tool.

5. The measurement method of the spatial pose guidance accuracy measurement device for a robot vision system according to claim 1, characterized in that, Step S3 further includes the following specific steps: S31: Within its maximum reachable motion space, the robot controls the target ball in the first target mount (51) at the robot's end effector to move M positions in the space, where M > 4, and the M positions are not in the same plane. The robot also records the coordinates (X, Y, X, Y) of the M positions on the robot's teach pendant. R1 Y R1 Z R1 ), (X) R2 Y R2 Z R2 )....(X) RM Y RM Z RM The laser tracker collects the coordinates of the target ball at M positions of the robot's end effector (X). V1 Y V1 Z V1 ), (X) V2 Y V2 Z V2 )....(X) VM Y VM Z VM ); S32: Given the coordinates of the center of the same target ball in the robot's base coordinate system and the coordinates of the laser tracker's measurement coordinate system, the pose relationship between the laser tracker's measurement coordinate system and the robot's base coordinate system can be solved. Based on the pose relationship between the two coordinate systems, the laser tracking measurement coordinate system {B} is made to coincide with the robot's base coordinate system {base}.

6. The measurement method of the spatial pose guidance accuracy measurement device for a robot vision system according to claim 1, characterized in that, Step S5 further includes the following specific steps: S51: In the laser tracker measurement system, the coordinates of the center points of the three cylindrical end faces are used, where the coordinates of the center points of the end faces of the first cylinder (2), the second cylinder (3), and the third cylinder (4) are FL2 (X) and FL2 (X). L2 Y L2 Z L2 ), FL3 (X) L3 Y L3 Z L3 ), FL4 (X L4 Y L4 Z L4 Construct direction vectors respectively. , , Construct a normal vector, take the center point of the end face of the first cylinder (2) as the origin of the coordinate system, and establish the calibration coordinate system {W} on the calibration flange (1) using the right-hand rule; S52: In the tracking measurement system, there is a coordinate system {B} that coincides with the robot base coordinate system {base}, and a coordinate system {W} of the calibration flange (1). The homogeneous matrix relationship between the two in the laser tracking measurement system can be used to determine the coordinate system. The pose relationship of the calibration flange (1) in the robot base coordinate system is calculated. The pose value is the theoretical value (Xc, Yc, Zc, ac, bc, cc) guided by the robot vision system.

7. The measurement method of the spatial pose guidance accuracy measurement device for a robot vision system according to claim 1, characterized in that, In step S7, after obtaining the actual spatial pose value guided by the first robot vision system, the following steps are also included: Repeat steps S6-S7 a total of n (n≥10) times. Through the robot vision system's n recognitions and guidance of its end-effector target ball to position A of the calibration flange (1), the tracker also performs n measurements on the actual pose of the robot tool's end-effector target ball. Thus, the pose result (X) guided by the robot vision system n times can be measured and calculated. i Y i Z i a i b i c i (where i = 1, 2, 3, ..., n).

8. The measurement method of the spatial pose guidance accuracy measurement device for a robot vision system according to claim 7, characterized in that, The spatial pose guidance accuracy of the robot vision system includes the position accuracy, attitude accuracy, position repeatability, and attitude repeatability of the robot vision system spatial pose guidance.

9. The measurement method of the spatial pose guidance accuracy measurement device for a robot vision system according to claim 8, characterized in that, Position accuracy (AP) of a robot vision system guided n times P The calculation formula is: ； in ; ； ； Attitude accuracy (AP) a AP b AP c ) , , ; in ; ； ； Location repeatability (RP) L ) ; in ; ； ； Posture repeatability (RP) a RP b RP c ) , , .

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