A measuring device and method for the accuracy of circular arc trajectory guidance of a robot vision system

Abstract

The application discloses a kind of robot vision system circular arc trajectory guide precision measuring device and method, it is related to robot guide technical field, robot vision system identifies the end face circle of the second cylinder of calibration flange, and generates point cloud based on the end face circle of the second cylinder, and the tool center point of vision system guided robot moves along the circumferential generatrix trajectory of the end face circle of the second cylinder, laser tracker measures actual motion trajectory after being guided by vision system in dynamic measurement mode, there is also the actual motion trajectory point position after being guided by vision system in laser tracking measurement system simultaneously based on the circumferential generatrix theoretical trajectory point position of the end face circle of the second cylinder, i.e., the guide precision of robot vision system spatial circular arc trajectory can be accurately measured and calculated.

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 circular arc trajectory guidance in a robot vision system. Background Technology

[0002] Robots are essential basic production equipment in industrial fields such as aviation, aerospace, defense, and machinery manufacturing. With the development towards Industry 4.0, the integration and application of robot systems are moving towards intelligence. This intelligence 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.

[0003] When a robot performs circular trajectory movements, the end effector of the robot tool will, in most cases, continuously change posture around the tool's center point throughout the entire operation. Therefore, the accuracy of the robot's "hand-eye" calibration determines whether the vision system can accurately guide the robot's spatial circular trajectory. In actual production, in applications such as welding trajectory guidance, glue application trajectory guidance, spraying trajectory guidance, and cutting trajectory guidance, the accuracy of the vision system's trajectory guidance is a key factor affecting the final product's processing quality.

[0004] Currently, there are no relevant testing standards or methods for the accuracy of spatial circular arc trajectory guidance in robot vision systems; Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a measuring device and method for the guidance accuracy of circular arc trajectories in robot vision systems, so as to accurately measure and calculate the guidance accuracy of spatial circular arc trajectories in robot vision systems.

[0006] This invention is achieved through the following technical solution:

[0007] A device for measuring the accuracy of circular arc trajectory guidance in a robot vision system, comprising:

[0008] A two-degree-of-freedom motion platform device, comprising a vertically arranged first linear motion servo axis and a horizontally arranged second linear motion servo axis;

[0009] A worktable is connected to the second linear motion servo axis, and the worktable can slide along the length direction of the second linear motion servo axis; a calibration flange is fixed on the worktable;

[0010] The calibration flange includes two coaxially connected first cylinders and second cylinders. The diameter of the first cylinder is larger than the diameter of the second cylinder, and the thickness of the second cylinder is equal to the radius of the target ball.

[0011] Further solutions:

[0012] The present invention also provides a measurement method for a device for measuring the accuracy of circular trajectory guidance in a robot vision system, comprising the following steps:

[0013] S0: The calibration flange is fixedly installed on the worktable of the two-degree-of-freedom motion platform device. The target ball moves at a uniform interval of M positions on the end face of the second cylinder of the calibration flange, M>6. The laser tracker measures the M points in sequence and fits the end plane of the second cylinder of the calibration flange based on the M measurement points.

[0014] S1: Move the worktable to a fixed position A, uniformly set at least three measurement points in the radial circumferential direction of the second cylinder, and move the target ball to several measurement points respectively. Measure the target ball coordinates at each point using a laser tracker, fit a circle based on several measurement points, and project the fitted circle onto the end plane of the second cylinder.

[0015] S2: Compensate for several measurement points along the radial direction of the end face circle of the second cylinder, so that all measurement points are on the circumference of the end face circle of the second cylinder.

[0016] S3: Adsorb the target ball onto the robot's end effector target holder and mark the robot's tool center point at the center of the target ball;

[0017] S4: Move the worktable to a fixed position B. In the dynamic measurement mode of the laser tracker, adjust the center point of the robot end tool to precisely coincide with the several measurement points after compensation in step S2. Operate the robot to teach and record the points P1..PN that coincide with the several measurement points; N is greater than or equal to 3.

[0018] S5: Based on several points P1..PN taught by the robot, use the arc trajectory instruction to compile and generate the corresponding arc trajectory running program;

[0019] S6: Run the robot's circular trajectory program, dynamically and in real time measure the robot's motion trajectory using a laser tracker, and obtain several sampling points of the circular trajectory of the robot starting from point P1 and passing through points P2, ... PN respectively. These sampling points serve as the theoretical values ​​for the circular trajectory guidance of the robot's vision system.

[0020] S7: Control the worktable to move to a fixed position A. The robot vision system identifies and scans the circumference generatrix of the second cylindrical end face circle, generating a vision system point cloud based on the circumference generatrix of the second cylindrical end face circle. Subsequently, the vision system guides the robot tool center point to move along the trajectory of the second cylindrical circumference generatrix. The actual movement trajectory of the robot after being guided by the vision system is dynamically measured in real time by a laser tracker, and the actual value of the arc trajectory guided by the robot vision system is obtained.

[0021] S8: Based on the theoretical value before trajectory guidance and the actual value after trajectory guidance, the trajectory accuracy of the robot vision system after spatial circular arc trajectory guidance is obtained.

[0022] In this scheme, the robot running speed values ​​in step S6 and step S7 are the same, and the sampling frequency values ​​for laser tracking dynamic measurement in step S6 and step S7 are the same.

[0023] Furthermore, step S1 also includes the following specific steps:

[0024] Measurement points 1, 2, and 3 are uniformly set along the radial circumference of the second cylinder, and the target ball is moved to measurement points 1, 2, and 3 respectively. The coordinate values ​​of the target ball at each point are measured by a laser tracker. A circle is fitted based on measurement points 1, 2, and 3, and the fitted circle is projected onto the end plane of the second cylinder.

[0025] Furthermore, step S3 includes the following specific steps:

[0026] S31: Move the robot to a suitable position, attach the target ball to the robot's end effector, and record the robot's pose P0; the robot orbits the flange coordinate system X around the 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 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.

[0027] S32: The robot returns to pose P0, 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 with the robot flange coordinate system;

[0028] S33: Measure the target ball coordinates at the robot end in the laser tracking coordinate system {F}. This value is the offset of the target ball center relative to the origin of the robot flange coordinate system. Import the target ball coordinates into the robot controller. At this time, the robot's tool center point is the target ball center.

[0029] Furthermore, in step S31, 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 S31. If none of the three included angles are within the range of 90°±0.03°, then repeat step S31.

[0030] Furthermore, the formula for calculating the angle between normal vectors is:

[0031]

[0032] Furthermore, in step S6, where N equals 3, the specific steps for obtaining several sampling points of the circular trajectory of the robot starting from point P1 and passing through points P2 and P3 by dynamically and in real time measuring the robot's motion trajectory using a laser tracker are as follows:

[0033] The laser tracker is set to a fixed sampling frequency Q Hz in dynamic measurement mode. The mobile robot tool center point moves to point P1 and automatically runs at a fixed speed S m / s, tracking the robot's 360° circular trajectory from point P1 through points P2 and P3. The laser tracker dynamically measures the robot's trajectory in real time at the fixed sampling frequency Q Hz and collects several sampling points C of the 360° circular trajectory from point P1 through points P2 and P3. i (Xc i Yc i Zc i ), where i = 1, 2, 3, 4…m, C i (Xc i Yc i Zc i This is the theoretical value for the circular trajectory guidance of the robot vision system.

[0034] Furthermore, in step S7, the vision system guides the robot tool's center point to move along the generatrix of the second cylinder's circumference. The specific steps for dynamically and in real-time measuring the robot's actual motion trajectory after being guided by the vision system using a laser tracker are as follows:

[0035] The robot control program sets the trajectory running speed S m / s. The robot vision system guides the robot tool's center point to move along the entire circumference of the second cylindrical end face at a fixed speed S m / s. The laser tracker dynamically measures the robot's motion trajectory after vision guidance in real time at a fixed sampling frequency of Q Hz, and collects several sampling points K of the motion trajectory after the robot vision system guidance. i (X i Y i Z i ), where i = 1, 2, 3, 4…m, K i (X i Y i Z i This is the actual value after the robot vision system guides the circular arc trajectory.

[0036] Furthermore, after the initial acquisition of several sampling points K of the spatial circular trajectory guided by the robot's vision system, i (X i Y i Z i Following this, the following steps are also included:

[0037] Repeat step S7 a total of n times (n≥10). Through n recognitions and scans by the robot's vision system, the vision system guides the robot's end-effector target ball to move along the entire circumference generatrix of the second cylindrical end face at a fixed speed S m / s. The laser tracker also performs n dynamic real-time measurements on the target ball (TCP) on the robot at a fixed sampling frequency Q Hz, and the coordinates K of the n measurement points can be obtained. ij (X ij Y ij Z ij ), where j = 1, 2, 3, 4…n.

[0038] Furthermore, the trajectory accuracy AT P The calculation formula is:

[0039] In the formula: i = 1, 2, 3, 4…m;

[0040]

[0041] The method for calculating trajectory repeatability after n-times circular arc trajectory guidance by the robot vision system is as follows:

[0042]

[0043] In the formula: i = 1, 2, 3, 4….m;

[0044]

[0045] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0046] This invention provides a device and method for measuring the accuracy of circular arc trajectory guidance in a robot vision system. Three measurement points are evenly distributed at 120° intervals along the radial circumference of a second cylinder. A target ball is sequentially moved to the three measurement points, and a laser tracker sequentially measures the target ball at each of the three measurement points. The results are then calculated based on the target ball radius value R along the calibration flange radius direction. 靶 Compensation is performed, ensuring that the three measurement points are all on the generatrix of the end face circle of the second cylinder. The robot tool center point is calibrated to the center of the target sphere. Based on the dynamic measurement function of the laser tracker, the robot tool center point is dynamically monitored and adjusted to coincide with the three measurement points evenly distributed at 120° on the generatrix of the end face circle of the second cylinder. The three points (P1, P2, P3) are taught and recorded. The robot uses an arc trajectory motion command and runs the arc trajectory command at a fixed speed S m / s in automatic mode. The laser tracker uses a dynamic measurement mode with a fixed sampling frequency Q Hz to measure the robot's arc motion trajectory. The coordinate values ​​of several points on the measured arc trajectory are the theoretical values ​​of the arc trajectory guidance accuracy of the vision system. The robot vision system identifies the generatrix of the end face circle of the second cylinder and generates a point cloud based on the generatrix of the end face circle of the second cylinder. The vision system guides the robot tool center point at a fixed speed S. The robot moves at m / s along the circumferential generatrix of the end face of the second cylinder. In dynamic measurement mode, the laser tracker measures the actual motion trajectory guided by the vision system at a fixed sampling frequency Q Hz. The laser tracking measurement system simultaneously has the theoretical trajectory points based on the circumferential generatrix of the end face of the second cylinder, as well as the actual motion trajectory points guided by the vision system. Therefore, the guidance accuracy of the robot vision system's spatial arc trajectory can be accurately measured and calculated.

[0047] In summary, for the same feature of the calibration flange, a laser tracker was used to measure the feature, and a vision system was used to scan and identify the feature. Before and after guidance, the robot vision system used a uniform running speed S m / s, and the laser tracker used a uniform dynamic sampling frequency Q Hz. Based on the above constraints, the theoretical value before guidance and the measured value after guidance of the robot vision system were obtained under the same experimental conditions. This allows for a precise, convenient, and quick measurement of the guidance accuracy of the circular trajectory of the robot vision system. 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 A schematic diagram of a space sphere fitted to the rotation of the robot end effector around the flange coordinate axis provided by the present invention;

[0050] Figure 2 This is a schematic diagram of the calibration flange provided by the present invention;

[0051] Figure 3 This is a schematic diagram of the structure of the two-degree-of-freedom motion platform device provided by the present invention;

[0052] Figure 4 This is a schematic diagram of the measurement layout provided by the present invention.

[0053] The attached diagram shows the markings and corresponding component names:

[0054] 1-First linear motion servo axis, 2-Second linear motion servo axis, 3-Worktable, 4-Calibration flange, 41-First cylinder, 42-Second cylinder. Detailed Implementation

[0055] 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.

[0056] Example 1:

[0057] This embodiment 1 provides a device for measuring the accuracy of circular arc trajectory guidance in a robot vision system, such as... Figure 2 and Figure 3 As shown, it includes: a two-degree-of-freedom motion platform device, which includes a vertically arranged first linear motion servo axis 1 and a horizontally arranged second linear motion servo axis 2; a worktable 3 is connected to the second linear motion servo axis 2, and the worktable 3 can slide along the length direction of the second linear motion servo axis 2; a calibration flange 4 is fixed on the worktable 3; the calibration flange 4 includes two coaxially connected first cylinder 41 and second cylinder 42, the diameter of the first cylinder 41 is larger than the diameter of the second cylinder 42, and the thickness of the second cylinder 42 is equal to the radius of the target ball.

[0058] In the aforementioned device, the calibration flange 4 includes a first cylinder 41 and a second cylinder 42, as shown below. Figure 2 As shown, the two-degree-of-freedom motion platform device includes a first linear motion servo axis 1, a second linear motion servo axis 2, and a worktable 3. Figure 3 As shown, the layout of the robot system, laser tracker, and calibration device throughout the measurement process is as follows: Figure 4 As shown. When the target ball moves on the calibration flange 4, the outer circumference of the second cylinder 42 of the calibration flange 4 radially positions the target ball, and the end face of the first cylinder 41 of the calibration flange 4 axially positions the target ball. The repeatability of the first linear motion servo axis 1 and the second linear motion servo axis 2 is better than 2μm, and the flatness of the worktable 3 is better than 3μm. The calibration flange 4 consists of two cylindrical stepped structures, namely the first cylinder 41 and the second cylinder 42, wherein the end faces of the first cylinder 41 and the second cylinder 42 are fixedly connected, and the diameter of the first cylinder 41 is... Greater than the second cylinder 42 The diameter. The thickness d2 of the second cylinder 42 and the radius R of the target ball. 靶 Equal, i.e., d2 = R 靶 The flatness of the end face of the first cylinder 41 is better than 2μm, the cylindricity of the second cylinder 42 is better than 2μm, and the flatness of the end face of the second cylinder 42 is better than 1μm.

[0059] Example 2:

[0060] This embodiment 2 further optimizes upon embodiment 1, providing a measurement method for a device used to measure the accuracy of circular trajectory guidance in a robot vision system, such as... Figures 1-4 As shown, the end effector of the robot tool revolves around the flange coordinate system X. F Y F Z F Axis rotation fitting sphere and spatial circle such as Figure 1 As shown, the specific steps include the following:

[0061] 1. Fix the calibration flange 4 onto the worktable 3 of the two-degree-of-freedom motion platform device, control the worktable 3 of the two-degree-of-freedom motion platform device to move to the fixed position A, and move the target ball to M positions (M>6) at uniform intervals on the end face of the second cylinder 42. The laser tracker measures the M points in sequence and fits the end plane of the second cylinder 42 based on the M measurement points.

[0062] 2. Measurement points 1, 2, and 3 are set in the radial circumference of the second cylinder 42. Measurement points 1, 2, and 3 are evenly distributed at 120° on the radial circumference of the second cylinder 42. When the target ball moves on the calibration flange 4, the outer circle of the second cylinder 42 of the calibration flange 4 radially positions the target ball, and the end face of the first cylinder 41 of the calibration flange 4 axially positions the target ball. The target ball moves to measurement points 1, 2, and 3 on the second cylinder 42 respectively. The laser tracker sequentially measures the coordinate values ​​of the target ball at each point, fits a circle based on measurement points 1, 2, and 3, and projects the fitted circle onto the end plane of the second cylinder 42.

[0063] 3. The three measurement points are based on the target sphere radius value R. 靶 Compensation is performed along the radial direction of the end face circle of the second cylinder 42, and the compensation measurement point D1(X) is obtained. D1 ,Y D1 Z D1 ), Measurement point D2(X D2 ,Y D2 Z D2 ), measurement point D3(X D3 ,Y D3 Z D3 All of them are on the circumference of the end face of the second cylinder 42.

[0064] 4. Move the robot to a suitable position, attach the target ball to the robot's end effector, and record the robot's pose P0. 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.

[0065] The equations for a space sphere are as follows: (xa) 2 +(yb) 2 +(zc) 2 =R 2 (1)

[0066] The equation is transformed as follows: 2ax + 2by + 2cz - a 2 -b 2 -c 2 +R 2 =x 2 +y 2 +z 2(2)

[0067] Let 2a = A, 2b = B, 2c = C, and a. 2 +b 2 +c 2 -R 2 =D;

[0068] The above equation can be written in matrix form as follows:

[0069]

[0070] The matrix is ​​transformed as follows:

[0071]

[0072] 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.

[0073] Space plane fitting:

[0074] The equation of the spatial plane can be expressed as: A1x + B1y + C1z + 1 = 0, (5)

[0075] The equation can be expressed in matrix form as follows:

[0076]

[0077] After matrix transformation, the following equation can be obtained:

[0078]

[0079] 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.

[0080] Construct the normal vectors of the circle and its plane that rotate around Rx, Ry, and Rz. Find 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°, 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.

[0081] 5. The robot returns to pose P0, 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 with the robot flange coordinate system.

[0082] 6. Measure the coordinates of the target ball in the laser tracking coordinate system {F}. This value is the offset of the target ball's center relative to the origin of the robot flange coordinate system (default TCP). Import the target ball's coordinates into the robot controller. At this time, the robot's tool center point (TCP) is the center of the target ball.

[0083] 7. The worktable 3 of the two-degree-of-freedom motion platform device moves to a fixed position B. In the dynamic measurement mode of the laser tracker, adjust the center point of the robot's end effector (target center) and D1(X) to... D1 ,Y D1 Z D1 Reconcile the teaching record with the current point P1, and adjust the center point of the robot's end effector (target center) and D2 (X) D2 ,Y D2 Z D2 Reconcile the teaching record and set the current point to P2. Adjust the center point of the robot's end effector (target center) to D3 (X). D3 ,Y D3 Z D3 The current point in the merged teaching record is P3.

[0084] 8. In the robot teach pendant, use the circular arc motion trajectory instruction to write a program for a 360° circular trajectory path starting from point P1 and passing through points P2 and P3 respectively, and set the trajectory running speed to S m / s.

[0085] 9. The laser tracker is set to a fixed sampling frequency Q Hz in dynamic measurement mode. The robot tool center point moves to point P1 and automatically runs at a speed S m / s, tracking the 360° circular trajectory of the robot starting from point P1 and passing through points P2 and P3. The laser tracker dynamically measures the robot's trajectory in real time at a sampling frequency of Q Hz. The laser tracker measurement system then has several sampling points C representing the 360° circular trajectory of the robot starting from point P1 and passing through points P2 and P3. i (X i Y i Z i ), where i = 1, 2, 3, 4…m, C i (Xc i Yc i Zc i This is the theoretical value for guiding the circular arc trajectory of the robot vision system.

[0086] 10. The worktable 3 of the two-degree-of-freedom motion platform device moves to a fixed position A. The robot vision system identifies and scans the circumference generatrix of the end face circle of the second cylinder 42, generating a vision system point cloud based on the circumference generatrix of the end face circle of the second cylinder 42. Then, the worktable 3 of the two-degree-of-freedom motion platform device moves to a fixed position B.

[0087] 11. In the robot control program, the trajectory running speed S m / s is set. The robot vision system guides the center point of the robot tool to run along the entire circumference of the end face of the second cylinder 42 at a speed of S m / s. The laser tracker dynamically measures the motion trajectory of the robot after vision guidance in real time at a sampling frequency of Q Hz. Several sampling points K of the motion trajectory after robot vision system guidance are obtained in the laser tracker measurement system. i (X i Y i Z i ), where i = 1, 2, 3, 4…m, K i (X i Y i Z i This is the actual value for the circular trajectory guidance of the robot vision system.

[0088] 12. Repeat steps 10-11 a total of n times (n≥10). Through n recognitions and scans by the robot vision system, the vision system guides the robot's target ball (TCP) to move along the entire circumferential generatrix of the end face of the second cylinder 42 of the calibration flange 4 at a fixed speed S m / s. The laser tracker also performs n dynamic real-time measurements on the target ball (TCP) on the robot at a fixed sampling frequency Q Hz, and the coordinates K of the n measurement points can be obtained. ij (X ij Y ij Z ij ), where j = 1, 2, 3, 4…n.

[0089] 13. With both the theoretical values ​​before and the measured values ​​after guidance from the robot vision system in the laser tracking measurement system, the trajectory accuracy AT after guidance by the robot vision system in the spatial circular arc can be calculated. P :in:

[0090]

[0091] In the formula:

[0092]

[0093] The method for calculating trajectory repeatability after n-times circular arc trajectory guidance by the robot vision system is as follows:

[0094]

[0095] In the formula:

[0096]

[0097] In summary, by designing and manufacturing a high-precision calibration flange 4, its laser tracker can conveniently and quickly measure three feature points distributed at 120° on the circumference of the second cylinder 42. Compensation based on the target ball radius is applied to the measurement points on the circumference of the second cylinder 42 of the calibration flange 4, ensuring that the three compensated feature points accurately fall on the circumference of the end face of the second cylinder 42 of the calibration flange 4. Through the dynamic measurement characteristics of the laser tracker, the target ball at the end of the robot tool is adjusted to allow the robot to teach and record the three feature points on the circumference of the second cylinder 42 of the calibration flange 4. A fixed running speed S m / s is set, and an arc trajectory based on the taught and recorded three feature points is executed using arc commands. The laser tracker measures the robot's arc trajectory using a fixed sampling frequency Q Hz in a dynamic measurement manner. This measurement result is the theoretical arc trajectory before guidance by the robot vision system. The robot vision system performs a differential scan of the generatrix of the circumference of the end face of the second cylinder 42 of the calibration flange 4 and guides the robot tool's center point at a fixed running speed S. The robot moves at a speed of m / s along the circular arc trajectory scanned by the vision system. The laser tracker still measures the robot's motion trajectory after vision guidance in a dynamic measurement manner at a fixed sampling frequency of Q Hz. The measurement result is the actual circular arc trajectory after the robot vision system guidance. In the laser tracking measurement system, both the theoretical circular arc trajectory before robot vision system guidance and the actual circular arc trajectory after robot vision system guidance are available, and the deviation between the two can be easily obtained. By repeatedly recognizing and guiding the robot vision system and measuring it with the laser tracker, the accuracy deviation and repeatability deviation of the circular arc trajectory guidance accuracy of the robot vision system can be obtained.

[0098] 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 device for measuring the accuracy of circular arc trajectory guidance in a robot vision system, characterized in that, The measuring device for the accuracy of circular trajectory guidance in a robot vision system includes: A two-degree-of-freedom motion platform device, comprising a first linear motion servo axis (1) arranged vertically and a second linear motion servo axis (2) arranged horizontally. A worktable (3) is connected to the second linear motion servo axis (2), and the worktable (3) can slide along the length direction of the second linear motion servo axis (2); a calibration flange (4) is fixed on the worktable (3). The calibration flange (4) includes two coaxially connected first cylinder (41) and second cylinder (42), the diameter of the first cylinder (41) is greater than the diameter of the second cylinder (42), and the thickness of the second cylinder (42) is equal to the radius of the target ball; The measurement method includes the following steps: S0: Fix the calibration flange (4) onto the worktable (3) of the two-degree-of-freedom motion platform device. Move the target ball at a uniform interval of M positions on the end face of the second cylinder (42) of the calibration flange (4), M>6. The laser tracker measures the M points in sequence and fits the end plane of the second cylinder (42) of the calibration flange (4) based on the M measurement points. S1: Move the worktable (3) to a fixed position A, uniformly set at least three measurement points in the entire radial circumference of the second cylinder (42), and move the target ball to several measurement points respectively. Measure the target ball coordinates at each point using a laser tracker, fit a circle based on several measurement points, and project the fitted circle onto the end plane of the second cylinder (42). S2: Compensate for several measurement points along the radial direction of the end face circle of the second cylinder, so that all measurement points are on the circumference of the end face circle of the second cylinder. S3: Adsorb the target ball onto the robot's end effector target holder and mark the robot's tool center point at the center of the target ball; S4: Move the workbench (3) to a fixed position B. In the dynamic measurement mode of the laser tracker, adjust the center point of the robot end tool to precisely coincide with the several measurement points after compensation in step S2. Operate the robot to teach and record the points P1..PN that coincide with the several measurement points respectively; N is greater than or equal to 3. S5: Based on several points P1..PN taught by the robot, use the arc trajectory instruction to compile and generate the corresponding arc trajectory running program; S6: Run the robot's circular trajectory program and dynamically measure the robot's motion trajectory in real time using a laser tracker to obtain several sampling points of the circular trajectory of the robot starting from point P1 and passing through points P2, ... PN. These sampling points serve as the theoretical values ​​before the robot's vision system guides the circular trajectory. S7: Control the workbench (3) to move to a fixed position A. The robot vision system recognizes and scans the circumference generatrix of the end face circle of the second cylinder (42) and generates a vision system point cloud based on the circumference generatrix of the end face circle of the second cylinder (42). Then, the vision system guides the center point of the robot tool to move along the trajectory of the circumference generatrix of the second cylinder (42). The actual movement trajectory of the robot after being guided by the vision system is dynamically measured in real time by a laser tracker to obtain the actual value of the arc trajectory guided by the robot vision system. S8: Based on the theoretical value before the robot vision system guides the circular arc trajectory and the actual value after the robot vision system guides the circular arc trajectory, obtain the trajectory accuracy after the robot vision system guides the circular arc trajectory.

2. The measurement method of the device for measuring the accuracy of circular arc trajectory guidance in a robot vision system according to claim 1, characterized in that, Step S1 further includes the following specific steps: Measurement points 1, 2, and 3 are uniformly set in the radial circumferential direction of the second cylinder, and the target ball is moved to measurement points 1, 2, and 3 respectively. The coordinate values ​​of the target ball at each point are measured by a laser tracker. A circle is fitted based on measurement points 1, 2, and 3, and the fitted circle is projected onto the end plane of the second cylinder.

3. The measurement method of the device for measuring the accuracy of circular arc trajectory guidance in a robot vision system according to claim 1, characterized in that, Step S3 includes the following specific steps: S31: Move the robot to a suitable position, attach the target ball to the robot's end effector, and record the robot's pose P0; the robot orbits the flange coordinate system X around the 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 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. S32: The robot returns to pose P0, 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 with the robot flange coordinate system; S33: Measure the target ball coordinates at the robot end in the laser tracking coordinate system {F}. This value is the offset of the target ball center relative to the origin of the robot flange coordinate system. Import the target ball coordinates into the robot controller. At this time, the robot's tool center point is the target ball center.

4. The measurement method of the device for measuring the accuracy of circular arc trajectory guidance in a robot vision system according to claim 3, characterized in that, In step S31, 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 S31. If none of the three included angles are within the range of 90°±0.03°, then repeat step S31.

5. The measurement method of the device for measuring the accuracy of circular arc trajectory guidance in a robot vision system according to claim 4, characterized in that, The formula for calculating the angle between normal vectors is: ， ， 。 6. The measurement method of the device for measuring the accuracy of circular arc trajectory guidance in a robot vision system according to claim 1, characterized in that, In step S6, where N equals 3, the specific steps for obtaining several sampling points of the robot's circular trajectory from point P1 through points P2 and P3 by dynamically and in real-time measuring the robot's motion trajectory using a laser tracker are as follows: The laser tracker is set to a fixed sampling frequency Q Hz in dynamic measurement mode. The mobile robot tool center point moves to point P1 and automatically runs at a fixed speed S m / s, tracking the robot's 360° circular trajectory from point P1 through points P2 and P3. The laser tracker dynamically measures the robot's trajectory in real time at the fixed sampling frequency Q Hz and collects several sampling points C of the 360° circular trajectory from point P1 through points P2 and P3. i (Xc) i Yc i Zc i ), where i = 1, 2, 3, 4…m, C i (Xc) i Yc i Zc i This is the theoretical value before the robot vision system guides the circular trajectory.

7. The measurement method of the device for measuring the accuracy of circular arc trajectory guidance in a robot vision system according to claim 1, characterized in that, In step S7, the vision system guides the center point of the robot tool to move along the trajectory of the generatrix of the second cylinder. The specific steps for dynamically and in real-time measuring the actual motion trajectory of the robot after being guided by the vision system using a laser tracker are as follows: The robot control program sets the trajectory running speed S m / s. The robot vision system guides the robot tool's center point to move along the entire circumference of the second cylindrical end face at a fixed speed S m / s. The laser tracker dynamically measures the robot's motion trajectory after vision guidance in real time at a fixed sampling frequency of Q Hz, and collects several sampling points K of the motion trajectory after the robot vision system guidance. i (X) i Y i Z i ), where i = 1, 2, 3, 4…m, K i (X) i Y i Z i This is the actual value after the robot vision system guides the circular arc trajectory.

8. The measurement method of the device for measuring the accuracy of circular arc trajectory guidance in a robot vision system according to claim 7, characterized in that, Several sampling points K of the spatial motion trajectory after the initial acquisition guided by the robot vision system were used. i (X) i Y i Z i Following this, the following steps are also included: Repeat step S7 a total of n times (n≥10). Through n recognitions and scans by the robot vision system, the vision system guides the robot's end-effector target ball to move along the entire circumference generatrix of the second cylindrical end face circle at a fixed speed S m / s. The laser tracker also performs n dynamic real-time measurements on the target ball (TCP) on the robot at a fixed sampling frequency Q Hz, and the coordinates K of the n measurement points can be obtained. ij (X) ij Y ij Z ij ), where j = 1, 2, 3, 4…n.

9. The measurement method of the device for measuring the accuracy of circular arc trajectory guidance in a robot vision system according to claim 8, characterized in that, The trajectory accuracy AT P The calculation formula is: In the formula: i = 1, 2, 3, 4…m; ， , ； The method for calculating trajectory repeatability after n circular arc trajectory guidance cycles by the robot vision system is as follows: ； In the formula: i = 1, 2, 3, 4….m; ； ； 。

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