A robot user coordinate system calibration device and method

Abstract

This invention provides a robot user coordinate system calibration device and method. The device includes a robot, a PSD fixture, a two-dimensional PSD position sensor, a laser light source, a three-dimensional displacement stage, a data acquisition card, and a host computer. The method involves: first, calibrating the user coordinate system using a three-point teaching method, and establishing a PSD tool coordinate system using a direct input method; second, controlling the robot to move sequentially to two positions with only different heights, and calculating the direction vector of the laser beam in the robot's base coordinate system using two measured values ​​obtained from the laser beam illuminating the photosensitive surface of the two-dimensional PSD position sensor; calculating the rotation of the new user coordinate system around its axis using the laser beam direction vector, and repeating the above operation iteratively to obtain the rotation of the user coordinate system around its axis that meets the deviation requirements; finally, compensating for the origin coordinates using the user coordinate system origin deviation value calculated from the last iteration's measured values. This calibration method achieves high-precision calibration of the robot's user coordinate system, is low-cost, and easy to implement.

Description

Technical Field

[0001] This invention relates to the field of industrial robot technology, and in particular to a robot user coordinate system calibration device and method. Background Technology

[0002] Terahertz pulses can image the interior of objects, but two conditions must be met: first, the terahertz wave must be incident perpendicularly on the object's surface; second, during point-by-point detection, the distance from the terahertz emission origin to the detection point on the object's surface must be equal. These two conditions limit the application of terahertz imaging technology to planar objects, making it difficult to apply to curved surfaces. To enable the application of terahertz imaging technology to curved objects, a series-type industrial robotic arm is introduced to hold the sample and allow it to move freely. After introducing the robotic arm, the Z-axis of the user coordinate system is established to coincide with the terahertz wave. The higher the coaxiality between the Z-axis of the user coordinate system and the terahertz wave, the higher the accuracy of the terahertz wave's perpendicular incidence on the object's surface. Therefore, high-precision calibration of the user coordinate system is required. Coordinate measuring machines (CMMs) can be used for robotic arm calibration, but these devices are large and require significant space for installation and use. Laser trackers can calibrate robotic arms with high precision, but they are very expensive and difficult to operate. Visual measurement methods can be used for robotic arm calibration, but these methods rely on algorithms, which are difficult to develop. Zhang Enzheng of Zhejiang Sci-Tech University published a national invention patent, "Self-calibration Device and Method for Industrial Robots Based on the Circumferential Closure Principle," patent number CN113752297A. This patent proposes a robot calibration method, which includes: using a robot-driven laser to illuminate the center point of the photosensitive surface of a two-dimensional PSD position sensor on a circumferentially closed device, obtaining a measured value of the photosensitive surface center position; and repeatedly rotating the circumferentially closed device to measure the photosensitive surface center position. Constraint equations are established to solve for and compensate for robot model parameter errors, thereby calibrating the robot's user coordinate system. This method uses complex equipment with high assembly precision requirements, and its operation steps are relatively complex, requiring multiple rotations of the circumferentially closed device for each iteration. Currently, there is no simple, accurate, low-cost robot calibration method applicable to terahertz imaging technology. Therefore, researching a robot calibration method for terahertz imaging technology has significant research significance and practical value. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a robot user coordinate system calibration device and method, which is low in cost and has high calibration accuracy, and can greatly improve the positioning accuracy of the robot.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a robot user coordinate system calibration device, comprising a robot (1), a PSD fixture (2), a two-dimensional PSD position sensor (3), a laser source (4), a three-dimensional displacement stage (5), a data acquisition card (6), and a host computer (7); the PSD fixture (2) is fixed at the end of the robot (1); the two-dimensional PSD position sensor (3) is fixed on the PSD fixture (2); the laser source (4) is fixed on the three-dimensional displacement stage (5); the data acquisition card (6) is used to acquire the analog voltage output by the two-dimensional PSD position sensor (3); the host computer (7) is connected to the data acquisition card (6) and is used to display the analog voltage of the two-dimensional PSD position sensor (3) and calculate the position of the centroid of the light spot; the robot (1) is used to drive the two-dimensional PSD position sensor (3) to move in three-dimensional space, so that the laser emitted by the laser source (4) irradiates the photosensitive surface of the two-dimensional PSD position sensor (3).

[0005] In a preferred embodiment, the robot (1) is a serial industrial robotic arm used to drive the two-dimensional PSD position sensor (3) to move freely in three-dimensional space.

[0006] In a preferred embodiment, the PSD clamp (2) has the functions of centering and clamping; the jaws (2-1) have a scale, and the position of the two-dimensional PSD position sensor (3) is manually adjusted according to the scale to achieve alignment between the center of the photosensitive surface in the y direction and the center of the PSD clamp (2). Then, the jaws (2-1) move on the positioning track (2-2) so that the inner sidewalls of the jaws on the left and right sides simultaneously abut against the two-dimensional PSD position sensor (3), thereby achieving alignment between the center of the photosensitive surface in the x direction and the center of the PSD clamp (2).

[0007] In a preferred embodiment, the three-dimensional displacement stage (5) is used to adjust the position of the laser source (4); the three-dimensional displacement stage (5) can adjust the position of the laser source (4) with high precision in the X, Y, and Z directions.

[0008] The present invention also provides a robot user coordinate system calibration method, which employs a robot user coordinate system calibration device and includes the following steps:

[0009] Step S1: Roughly calibrate the user coordinate system {O-XYZ} using the three-point teaching method, and calibrate the PSD tool coordinate system {O} using the direct input method. p -X p Y p Z pThe origin of the user coordinate system is theoretically established in the emission direction of the laser source (4), and the negative Z-axis of the user coordinate system is theoretically consistent with the direction of the laser beam emitted by the laser source (4); the origin of the PSD tool coordinate system coincides with the center of the photosensitive surface of the two-dimensional PSD position sensor (3), and the Z-axis of the PSD tool coordinate system is... p The axis is perpendicular to the photosensitive surface of the two-dimensional PSD position sensor (3);

[0010] Step S2: Control the robot (1) to move the two-dimensional PSD position sensor (3) to the position (0,0,0,0,0,0) in the user coordinate system {O-XYZ}. Columns 1-3 are the coordinate values ​​of X, Y, and Z in the user coordinate system {O-XYZ}, and columns 4-6 are the rotation values ​​around the X, Y, and Z axes. Since the rotation values ​​are all 0, it indicates that the axes of the PSD tool coordinate system are parallel to the axes of the user coordinate system. The acquisition card (6) acquires the analog voltage value generated by the laser beam emitted by the laser source (4) illuminating the two-dimensional PSD position sensor (3). The host computer (7) calculates the position of the centroid of the light spot on the photosensitive surface of the two-dimensional PSD position sensor (3) based on the analog voltage value. Simultaneously record the robot's joint angle values ​​at this time, where i represents the i-th iteration;

[0011] Step S3: Control the robot (1) to move the two-dimensional PSD position sensor (3) to the position (0,0,z,0,0,0) in the user coordinate system {O-XYZ}, where z<0; the acquisition card (6) acquires the analog voltage value generated by the laser beam emitted by the laser source (4) illuminating the two-dimensional PSD position sensor (3), and the host computer (7) calculates the position of the centroid of the light spot on the photosensitive surface of the two-dimensional PSD position sensor (3) based on the analog voltage value. Simultaneously record the robot's joint angle values ​​at this time;

[0012] Step S4: If the above Point and Point position deviation If it is greater than or equal to the threshold δ, then use Calculate the direction vector of the laser beam in the robot's base coordinate system {O'-X'Y'Z'}. If the position deviation Δδ < δ, it means that the laser beam direction vector is parallel to the Z-axis of the user coordinate system at this time, and the next step is to execute step S6;

[0013] Step S5: with As the Z-axis direction vector of the new user coordinate system under the robot base coordinate system {O'-X'Y'Z'}, calculate the X-axis and Y-axis direction vectors of the new user coordinate system; use the direction vectors of each axis of the new user coordinate system to calculate the rotation around the axes w, p, and r of the robot base coordinate system {O'-X'Y'Z'} when transformed to the new user coordinate system {O-XYZ}; apply the obtained rotation around the axes in the new user coordinate system and return to step S2;

[0014] Step S6: Utilize the last iteration The coordinate values ​​are used to calculate the origin deviation of the user coordinate system and to compensate for the origin coordinates.

[0015] In a preferred embodiment, step S2 involves calculating the position of the spot centroid on the photosensitive surface of the two-dimensional PSD position sensor (3) based on the analog voltage value. The specific calculation steps are as follows:

[0016] The analog voltage V is obtained using step S2. sx V sy V dx V dy Calculate the position of the centroid of the light spot, where V sx It is the sum of the voltages of the two electrodes along the x-axis, V dx It is the voltage difference between the two electrodes along the x-axis, V. sy It is the sum of the voltages at the two electrodes along the y-axis, V dy It is the voltage difference between the two electrodes along the y-axis. The size of the photosensitive surface of the two-dimensional PSD position sensor (3) is 2L×2L (mm). 2 );

[0017] The formula for the centroid of the light spot detected by PSD can be used to calculate:

[0018] In a preferred embodiment, in step S4 The specific calculation steps are as follows:

[0019] When the robot moves to the position (0,0,0,0,0,0), the angle readings of each joint of the robot are used to obtain the result. Three-dimensional position in the robot's base coordinate system {O'-X'Y'Z'}

[0020] According to the formula:

[0021] Known θ j α j-1 a j-1 d jThese represent the joint angle, torsion angle, link length, and link offset parameters of the j-th joint when the robot moves to a certain position. This represents the pose matrix of the robot's end effector in the robot's base coordinate system {O'-X'Y'Z'} when the robot moves to the position (0,0,0,0,0,0). Represents the PSD tool coordinate system {O p -X p Y p Z p The pose matrix at the robot's end effector;

[0022] Similarly, according to the formula calculate Three-dimensional position in the robot's base coordinate system {O'-X'Y'Z'}

[0023] Find:

[0024] In a preferred embodiment, the specific steps of step S5, which calculates the rotations w, p, and r around the axes when transforming the robot's base coordinate system {O'-X'Y'Z'} to the new user coordinate system {O-XYZ}, are as follows:

[0025] It is the direction vector of the laser beam, and also the negative direction vector of the Z-axis of the new user coordinate system to be calibrated. Take vector Using vectors and Obtain the direction vector of the Y-axis of the new user coordinate system.

[0026]

[0027] Using vectors and Calculate the direction vector of the X-axis in the new user coordinate system.

[0028] Let the direction vector of the robot's base coordinate system be:

[0029]

[0030] In the rotation transformation about the axes, the rotation matrix for rotation w about the X-axis is R(w), the rotation matrix for rotation p about the Y-axis is R(p), and the rotation matrix for rotation r about the Z-axis is R(r), as shown below:

[0031]

[0032] The order of rotation from the robot's base coordinate system to the user's coordinate system is: first around the X' axis, then around the Y' axis, and finally around the Z' axis, resulting in the rotation matrix R:

[0033]

[0034] Furthermore, the rotation matrix of the new user coordinate system {O-XYZ} relative to the robot base coordinate system {O'-X'Y'Z'} is:

[0035]

[0036] Therefore, we can obtain:

[0037]

[0038] in:

[0039]

[0040] Apply the obtained w, p, and r to the new user coordinate system and return to step S2.

[0041] In a preferred embodiment, step S6 specifically comprises the following steps:

[0042] obtained using the last iteration and Coordinate values, calculate average Origin of the original user coordinate system O(x) o ,y o ,z o Adjusted to

[0043]

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The device provided by this invention has a simple structural design and is highly practical.

[0046] 2. The calibration method provided by this invention uses PSD and other equipment that are much cheaper than the equipment used in other methods, giving it a significant price advantage.

[0047] 3. The calibration method provided by this invention requires minimal and readily available raw information, enabling rapid and accurate calibration of the robot workpiece coordinate system. After calibration, the absolute positioning accuracy of the robot is significantly improved, demonstrating broad application prospects. Attached Figure Description

[0048] Figure 1 This is a system composition diagram of the calibration device according to a preferred embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the PSD fixture clamping a two-dimensional PSD position sensor in the calibration device of a preferred embodiment of the present invention;

[0050] Figure 3 This is a schematic flowchart of the calibration method according to a preferred embodiment of the present invention;

[0051] Figure 4 This is a diagram showing the measurement results after calibrating the user coordinate system according to a preferred embodiment of the present invention.

[0052] In the diagram: 1-Robot, 2-PSD fixture, 3-2D PSD position sensor, 4-Laser light source, 5-3D displacement stage, 6-Acquisition card, 7-Host computer. Detailed Implementation

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0054] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0055] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0056] like Figure 1-4 As shown, this embodiment provides a robot user coordinate system calibration device. The device includes a robot (1), a PSD fixture (2), a two-dimensional PSD position sensor (3), a laser source (4), a three-dimensional displacement stage (5), a data acquisition card (6), and a host computer (7). The PSD fixture (2) is fixed at the end of the robot (1). The two-dimensional PSD position sensor (3) is fixed on the PSD fixture (2). The laser source (4) is fixed on the three-dimensional displacement stage (5). The data acquisition card (6) is used to acquire the analog voltage output by the two-dimensional PSD position sensor (3). The host computer (7) is connected to the data acquisition card (6) and is used to display the analog voltage of the two-dimensional PSD position sensor (3) and calculate the position of the centroid of the light spot. The robot (1) is used to drive the two-dimensional PSD position sensor (3) to move in three-dimensional space so that the laser emitted by the laser source (4) irradiates the photosensitive surface of the two-dimensional PSD position sensor (3).

[0057] In this embodiment, the robot (1) is a serial industrial robotic arm used to drive the two-dimensional PSD position sensor (3) to move freely in three-dimensional space.

[0058] In this embodiment, the PSD fixture (2) has the functions of alignment and clamping. Specifically, as Figure 2 As shown, the jaw (2-1) has a scale. The position of the two-dimensional PSD position sensor (3) is manually adjusted according to the scale to align the center of the photosensitive surface in the y direction with the center of the PSD fixture (2). Then, the jaw (2-1) moves on the positioning track (2-2) so that the inner sidewalls of the jaw on the left and right sides simultaneously abut against the two-dimensional PSD position sensor (3), thereby aligning the center of the photosensitive surface in the x direction with the center of the PSD fixture (2).

[0059] In this embodiment, the three-dimensional displacement stage (5) is used to adjust the position of the laser source (4), and the position of the laser source (4) can be adjusted with high precision in the X, Y and Z directions.

[0060] like Figure 3 As shown, the robot user coordinate system calibration method based on the above-mentioned device provided in this embodiment includes the following steps:

[0061] Step S1: Roughly calibrate the user coordinate system {O-XYZ} using the three-point teaching method, and calibrate the PSD tool coordinate system {O} using the direct input method. p -X p Y p Z p The origin of the user coordinate system is theoretically established on the emission direction of the laser source (4), and the negative Z-axis of the user coordinate system is theoretically consistent with the direction of the laser beam emitted by the laser source (4); the origin of the PSD tool coordinate system coincides with the center of the photosensitive surface of the two-dimensional PSD position sensor (3), and the Z-axis of the PSD tool coordinate system is... p The axis is perpendicular to the photosensitive surface of the two-dimensional PSD position sensor (3).

[0062] Step S2: Control the robot (1) to move the two-dimensional PSD position sensor (3) to the position (0,0,0,0,0,0) in the user coordinate system {O-XYZ}. Columns 1-3 are the coordinate values ​​of X, Y, and Z in the user coordinate system {O-XYZ}, and columns 4-6 are the rotation values ​​around the X, Y, and Z axes. Since the rotation values ​​are all 0, it indicates that the axes of the PSD tool coordinate system are parallel to the axes of the user coordinate system. The acquisition card (6) acquires the analog voltage value generated when the laser beam emitted by the laser source (4) illuminates the two-dimensional PSD position sensor (3). The host computer (7) calculates the position of the centroid of the light spot on the photosensitive surface of the two-dimensional PSD position sensor (3) based on the analog voltage value. Simultaneously record the robot's joint angle values ​​at this time, where i represents the i-th iteration.

[0063] Step S3: Control the robot (1) to move the two-dimensional PSD position sensor (3) to the position (0,0,z,0,0,0) in the user coordinate system {O-XYZ}, where z<0; the acquisition card (6) acquires the analog voltage value generated by the laser beam emitted by the laser source (4) illuminating the two-dimensional PSD position sensor (3), and the host computer (7) calculates the position of the centroid of the light spot on the photosensitive surface of the two-dimensional PSD position sensor (3) based on the analog voltage value. Simultaneously record the robot's joint angle values ​​at this time.

[0064] Step S4: If the above Point and Point position deviation If it is greater than or equal to the threshold δ, then use Calculate the direction vector of the laser beam in the robot's base coordinate system {O'-X'Y'Z'}. If the position deviation Δδ < δ, it means that the laser beam direction vector is parallel to the Z-axis of the user coordinate system. The next step is to execute step S6.

[0065] Step S5: with Using the Z-axis direction vector of the new user coordinate system under the robot's base coordinate system {O'-X'Y'Z'}, calculate the direction vectors of the X and Y axes of the new user coordinate system. Using the direction vectors of each axis of the new user coordinate system, calculate the rotation amounts w, p, and r around the axes when transforming the robot's base coordinate system {O'-X'Y'Z'} to the new user coordinate system {O-XYZ}. Apply the obtained rotation amounts around the axes to the new user coordinate system and return to step S2.

[0066] Step S6: Utilize the last iteration The coordinate values ​​are used to calculate the origin deviation of the user coordinate system and to compensate for the origin coordinates.

[0067] In this embodiment, steps S1-S3 are implemented. The results of the centroid position of the detection spot of the two-dimensional PSD position sensor at different heights are shown in the table below. This indicates that the Z-axis of the user coordinate system has a large angle with the laser beam direction, and the user coordinate system needs to be calibrated.

[0068] Table 1. Centroid positions of the detection spot of the 2D PSD position sensor at different heights.

[0069]

[0070]

[0071] In this embodiment, step S2 involves calculating the position of the light spot centroid on the photosensitive surface of the two-dimensional PSD position sensor (3) based on the simulated voltage value. The specific calculation steps are as follows:

[0072] The analog voltage V is obtained using step S2. sx V sy V dx V dy Calculate the position of the centroid of the light spot, where V sx It is the sum of the voltages of the two electrodes along the x-axis, V dx It is the voltage difference between the two electrodes along the x-axis, V. sy It is the sum of the voltages at the two electrodes along the y-axis, V dy It is the voltage difference between the two electrodes along the y-axis. The size of the photosensitive surface of the two-dimensional PSD position sensor (3) is 2L×2L (mm). 2 ).

[0073] The formula for the centroid of the light spot detected by PSD can be used to calculate:

[0074] In this embodiment, step S4 The specific calculation steps are as follows:

[0075] When the robot moves to the position (0,0,0,0,0,0), the three-dimensional position of A1i in the robot's base coordinate system {O-X'Y'Z'} is obtained by using the joint angle readings of the robot.

[0076] According to the formula:

[0077] Known θ j α j-1 a j-1 d j These represent the joint angle, torsion angle, link length, and link offset parameters of the j-th joint when the robot moves to a certain position, respectively. This represents the pose matrix of the robot's end effector in the robot's base coordinate system {O'-X'Y'Z'} when the robot moves to the position (0,0,0,0,0,0). Represents the PSD tool coordinate system {OX p Y p Z p The pose matrix at the robot's end effector.

[0078] Similarly, according to the formula calculate Three-dimensional position in the robot's base coordinate system {O-X'Y'Z'}

[0079] Find:

[0080] In this embodiment, step S5 calculates the rotation amounts w, p, and r around the axes when the robot's base coordinate system {O'-X'Y'Z'} is transformed to the new user coordinate system {O-XYZ}. The specific steps are as follows:

[0081] It is the direction vector of the laser beam, and also the negative direction vector of the Z-axis of the new user coordinate system to be calibrated. Take vector Using vectors and The direction vector of the Y-axis in the new user coordinate system

[0082]

[0083] Using vectors and Calculate the direction vector of the X-axis in the new user coordinate system.

[0084]

[0085] Let the direction vector of the robot's base coordinate system be:

[0086]

[0087] In the rotation transformation about the axes, the rotation matrix for rotation w about the X-axis is R(w), the rotation matrix for rotation p about the Y-axis is R(p), and the rotation matrix for rotation r about the Z-axis is R(r), as shown below:

[0088]

[0089] The order of rotation from the robot's base coordinate system to the user's coordinate system is: first around the X' axis, then around the Y' axis, and finally around the Z' axis, resulting in the rotation matrix R:

[0090]

[0091] Furthermore, the rotation matrix of the new user coordinate system {O-XYZ} relative to the robot base coordinate system {O'-X'Y'Z'} is:

[0092]

[0093] Therefore, we can obtain:

[0094]

[0095] in:

[0096]

[0097] Apply the obtained w, p, and r to the new user coordinate system and return to step S2.

[0098] In this embodiment, step S6 specifically involves the following steps:

[0099] obtained using the last iteration and Coordinate values, calculate average Origin of the original user coordinate system O(x) o ,y o ,z o Adjusted to

[0100] like Figure 4 The image shows the robot moving to (0,0,z) after the user coordinate system has been calibrated. k Position z, 0,0,0) k This image shows the height values ​​of the controlled robot at different heights, and the results of multiple measurements of the spot centroid position at different heights. The average value of the spot centroid position at different heights is also shown. Standard deviation of x SD x =0.011, the standard deviation of y is SD y =0.008, the standard deviation is very small, indicating that these values ​​are very close to the mean and the values ​​are relatively stable. The distance from the origin can be calculated using the mean. Since the robot's repeatability is ±0.02mm, the distance error is considered to be caused by the repeatability and cannot be eliminated. After calibrating the user coordinate system, the robot's accuracy decreased from 0.75x to... y was reduced from 0.15 to Therefore, it is believed that after the user coordinate system is calibrated, it can accurately hit the center of the photosensitive surface of the two-dimensional PSD position sensor at different heights, indicating that the Z-axis of the user coordinate system has coincided with the laser beam, and the calibration has been achieved.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A robot user coordinate system calibration method, characterized by A robot user coordinate system calibration device is adopted, which includes a robot (1), a PSD fixture (2), a two-dimensional PSD position sensor (3), a laser source (4), a three-dimensional displacement stage (5), a data acquisition card (6), and a host computer (7); the PSD fixture (2) is fixed at the end of the robot (1); the two-dimensional PSD position sensor (3) is fixed on the PSD fixture (2); the laser source (4) is fixed on the three-dimensional displacement stage (5); the data acquisition card (6) is used to acquire the analog voltage output by the two-dimensional PSD position sensor (3); the host computer (7) is connected to the data acquisition card (6) and is used to display the analog voltage of the two-dimensional PSD position sensor (3) and calculate the position of the centroid of the light spot; the robot (1) is used to drive the two-dimensional PSD position sensor (3) to move in three-dimensional space so that the laser emitted by the laser source (4) irradiates the photosensitive surface of the two-dimensional PSD position sensor (3); the calibration method includes the following steps: Step S1: Roughly calibrate the user coordinate system using the three-point teaching method. Use direct input method to calibrate the PSD tool coordinate system The origin of the user coordinate system is theoretically established in the emission direction of the laser source (4), and the user coordinate system's... The negative axis direction is theoretically consistent with the direction of the laser beam emitted by the laser source (4); the origin of the PSD tool coordinate system coincides with the center of the photosensitive surface of the two-dimensional PSD position sensor (3), and the PSD tool coordinate system The axis is perpendicular to the photosensitive surface of the two-dimensional PSD position sensor (3); Step S2: Control the robot (1) to move the two-dimensional PSD position sensor (3) so that the robot moves to the user coordinate system. Below Location, where columns 1-3 are the user coordinate system. Down , , The coordinate values, columns 4-6 are around axis, axis, The rotation of the axis, since the values ​​of the rotation are all 0, indicates that at this time, each axis of the PSD tool coordinate system is parallel to each axis of the user coordinate system; the acquisition card (6) acquires the analog voltage value generated when the laser beam emitted by the laser source (4) illuminates the two-dimensional PSD position sensor (3), and the host computer (7) calculates the position of the centroid of the spot on the photosensitive surface of the two-dimensional PSD position sensor (3) based on the analog voltage value. Simultaneously, the robot's joint angle values ​​are recorded, where, Indicates the first The next iteration; Step S3: Control the robot (1) to move the two-dimensional PSD position sensor (3) so that the robot moves to the user coordinate system. Below Location, among which <0; The acquisition card (6) acquires the analog voltage value generated when the laser beam emitted by the laser source (4) illuminates the two-dimensional PSD position sensor (3). The host computer (7) calculates the position of the spot centroid on the photosensitive surface of the two-dimensional PSD position sensor (3) based on the analog voltage value. At the same time, the robot's joint angle values ​​are recorded. Step S4: If the above Point and Point position deviation Greater than or equal to the threshold Then utilize , Coordinate value calculation of the laser beam in the robot's base coordinate system Downward direction vector If the position is deviated This indicates that the laser beam direction vector is perpendicular to the user coordinate system at this time. With the axes parallel, proceed to step S6. Step S5: with As the robot's base coordinate system New user coordinate system Axis direction vectors, used to calculate the new user coordinate system shaft and The direction vectors of the axes; using the direction vectors of each axis in the new user coordinate system to calculate the robot's base coordinate system. Transform to the new user coordinate system Rotation around the axis , , Apply the obtained rotation around the axis to the new user coordinate system and return to step S2. Step S6: Utilize the last iteration , The coordinate values ​​are used to calculate the origin deviation of the user coordinate system and to compensate for the origin coordinates.

2. The robot user coordinate system calibration method according to claim 1, characterized in that, The position of the light spot centroid on the photosensitive surface of the two-dimensional PSD position sensor (3) is calculated based on the simulated voltage value in step S2. The specific calculation steps are as follows: The analog voltage is obtained using step S2. , , , Calculate the position of the centroid of the light spot, where yes The sum of the voltages at the two electrodes of the shaft. yes The voltage difference between the two electrodes of the shaft, yes The sum of the voltages at the two electrodes of the shaft. yes The voltage difference between the two electrodes of the axis, the size of the photosensitive surface of the two-dimensional PSD position sensor (3) is ; The formula for the centroid of the light spot detected by PSD can be used to calculate: , .

3. The robot user coordinate system calibration method according to claim 1, characterized in that, In step S4 The specific calculation steps are as follows: The robot moved to Positioning is determined using the readings of each joint angle of the robot. In the robot's base coordinate system The three-dimensional position below : According to the formula: , Known , , , , These represent the positions the robot moves to when it reaches, i.e., the first... The joint angle, torsion angle, link length, and link offset parameters of each joint; Indicates that the robot has moved to When positioning, the robot end effector is in the robot base coordinate system. The pose matrix below; Representing the PSD tool coordinate system The pose matrix at the robot's end effector; Similarly, according to the formula calculate In the robot's base coordinate system The three-dimensional position below ; Find: .

4. The robot user coordinate system calibration method according to claim 1, characterized in that, Step S5 calculates the robot's base coordinate system. Transform to the new user coordinate system Rotation around the axis , , The specific steps are as follows: It is the direction vector of the laser beam, and also the new user coordinate system that will be calibrated. The negative direction vector of the axis, then Take vector Using vectors and Obtain the new user coordinate system Direction vector of the axis : Using vectors and Calculate the new user coordinate system Direction vector of the axis : Let the direction vector of the robot's base coordinate system be: In the rotation transformation about an axis, around Axis rotation The rotation matrix is , around Axis rotation The rotation matrix is , around Axis rotation The rotation matrix is As shown below: The order of rotation from the robot's base coordinate system to the user coordinate system is: first rotate around... Axis, then around Axis, finally around Rotate the axis to obtain the rotation matrix. : Furthermore, due to the new user coordinate system Relative to the robot's base coordinate system The rotation matrix is: Therefore, we can obtain: in: The obtained , , Apply to the new user coordinate system and return to step S2.

5. The robot user coordinate system calibration method according to claim 1, characterized in that, The specific steps of step S6 are as follows: obtained using the last iteration and Coordinate values, calculate average Origin of the original user coordinate system Adjusted to .

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