Spraying robot calibration device and method

Abstract

The invention discloses a spraying robot calibration device and method. The method comprises the steps that S100, a calibration block is placed in a working space where the tail end of a robot can reach and fixed; establishing a coordinate system; s200, the tail end of the robot makes contact with the vertex of the bevel edge of the calibration block through a demonstrator, and the robot lifting joint length and other joint angles of the point are recorded; s300, a dragging teaching mode is used, a measuring tool at the tail end of the robot makes contact with the three planes and the inclined planes, perpendicular to one another, of the calibration block, multi-set point measurement is conducted, and then the corresponding robot nominal theoretical poses, namely the robot lifting joint length and other joint angles are recorded; and S400, the nominal position of the tail end of the robot and the actual position based on the calibration block mechanical structure are subjected to error comparison, and kinematics parameters of the robot are calibrated. The actual parameters of the robot are obtained at low cost through the calibration device.

Description

Technical Field

[0001] The present invention relates to the technical field of spraying robots, and in particular to a spraying robot calibration device and method. Background Art

[0002] Robot calibration block calibration means driving the end to a set of spatial position points that meet certain geometric constraints without using any external measuring equipment, and then using the position constraint relationship between the measured points to establish a set of equations according to the error model, thereby improving the positioning accuracy and motion control accuracy of the robot. Through the calibration block calibration method, only the robot's internal sensors can be used to determine the model's kinematic parameters and the robot's own posture and other parameters, and they can be adjusted to ensure the robot's absolute positioning accuracy, simplify the calibration workflow, and improve production efficiency.

[0003] In order to improve the spraying quality, reduce the impact of the differences in coatings and spraying devices with different fluid concentrations on the sprayed layer, and meet the demand for high-precision spraying of spray robots, the influence of factors that affect the accuracy of spray robots due to manufacturing and installation by robot manufacturers when they leave the factory is reduced. The use of calibration blocks can easily, quickly, and at low cost obtain the actual geometric parameters of the spray robot, and improve the absolute positioning accuracy of the robot.

[0004] Existing technologies, such as the Chinese invention patent with publication number CN112692833A, propose a method of using a camera to perform self-calibration on a special calibration block; the existing defects are that the 20° tilt angle is more likely to produce processing errors and increase the complexity of the objective function. The available planes are 3 planes, and all parameters cannot be identified.

[0005] The Chinese invention patent with publication number CN117283556A proposes a robot self-calibration device and method with a calibration plate with calibration holes; the defects thereof are that the calibration plate with calibration holes cannot fix the robot with lifting joints in the calibration holes, and a single calibration hole has few identifiable parameters and the effect after identification and compensation is not good.

[0006] Problems with existing technologies:

[0007] (1) Camera calibration places high demands on the operator. When the calibration block with a convex surface is calibrated using a plane, the robot objective function itself has partial errors due to the inclination of 20°, which increases the error amount.

[0008] (2) A single calibration plate can only calibrate some kinematic parameters of the spray robot, resulting in low calibration accuracy. Summary of the invention

[0009] In order to overcome the above technical problems, the purpose of the present invention is to provide a spray robot calibration device and method, which are easy to process, low cost, and can identify the kinematic parameters of lifting joints and six-degree-of-freedom robotic arms, so as to achieve the purpose of obtaining the actual parameters of the robot at low cost using a calibration device.

[0010] In order to achieve the above object, the technical solution adopted by the present invention is:

[0011] A spraying robot calibration device comprises a main control and a robot connected to the main control, wherein the main control comprises a robot control box and a computer system; a measuring device is arranged at the end of the robot through a flange; the robot control box is used to control the movement of the robot and the measuring device, and the computer system is used to store movement information of the robot and the measuring device;

[0012] The robot comprises a base joint 1, a lifting joint 2 and a six-degree-of-freedom robotic arm 3;

[0013] The measuring device comprises a metal probe 4 of the same size as the end of the robot and a calibration block 5 with an inclined surface, the metal probe 4 is mounted at the end of a six-degree-of-freedom robot arm 3, and the calibration block 5 contacts the calibration plane through the end of the robot;

[0014] The measuring device obtains the position and posture transformation of the calibration block 5 relative to the robot base coordinates by contacting the vertices of the inclined surface edge of the calibration block 5 with the metal probe 4.

[0015] The robot performs contact measurement on a vertex of the hypotenuse of the calibration block 5 to form a limit position that limits the movement of the robot end and the lifting joint 2, and obtains a coordinate transformation matrix based on the robot base coordinate system, that is, the nominal posture of the robot is obtained based on the robot joint angle at the limit position and the length of the lifting joint 2, and the minimum error between the nominal posture and the actual posture is solved to realize the calibration of the spray robot.

[0016] The calibration block 5 is a trapezoid with an inclination angle of 45°. The top surface size of the other five planes is 200x200mm, and the size of the inclined surface relative to the plane is the same as that of the top surface. The lower base of the two adjacent trapezoids is 400mm, the upper base is 200mm, the height is 200mm, and the bottom surface size is 200mmx400mm. The above five planes are perpendicular to each other except the opposite plane.

[0017] A calibration method for a spraying robot calibration device comprises the following steps:

[0018] S100: The calibration block 5 is placed in the workspace reachable by the robot end and fixed; a coordinate system is established;

[0019] S200: Use the teaching pendant to make the end of the robot contact the vertex of the hypotenuse of the calibration block 5, and record the length of the robot lifting joint 2 and the angles of the other joints at that point;

[0020] S300: Using the drag teaching method, the robot end measurement tool is allowed to contact the three mutually perpendicular planes and the inclined plane of the calibration block 5 respectively, and multiple groups of point measurements are performed respectively, and then the corresponding robot nominal theoretical posture, i.e., the length of the robot lifting joint 2 and the angles of the other joints are recorded;

[0021] S400: Compare the error between the nominal position of the robot end and the actual position based on the mechanical structure of the calibration block 5, and calibrate the robot kinematic parameters.

[0022] The step S100 includes establishing a base coordinate system {00X0Y0Z0} at the center of the robot base, and establishing a tool coordinate system {00X0Y0Z0} on the robot end measurement device. T X T Y T Z T}, establish the world coordinate system at the vertex of the hypotenuse of calibration block 5 {O w X w Y w Z w};

[0023] The robot tool is calibrated through the robot base coordinate system {O0X0Y0Z0}} to the position and posture relationship of the robot end, and the robot tool coordinate system {O T X T Y T Z T}, the pose transformation and position of the robot tool end in the robot base coordinates can be obtained.

[0024] The step S200 includes: the robot end tool contacts the vertex of the inclined surface of the calibration block 5 to obtain the base coordinate system {O0X0Y0Z0} to the world coordinate system {O w X w Y w Z w} coordinate transformation, connect the robot with a computer, obtain the length of the robot's lifting joint 2 and the angles of the other joints and record them, establish a kinematic model through the MDH method, and substitute the recorded data to obtain the coordinate transformation from the base coordinate to the world coordinate.

[0025] In the S300, the method of using dragging to teach the specific operation measurement is to allow the robot end measurement tool to contact the calibration block 5 plane to perform multiple point measurements. After seeing that the robot end measurement tool contacts the calibration block 5 plane, the corresponding robot lifting joint 2 length and the remaining joint angles are recorded to obtain the nominal theoretical position of the robot on the calibration block 5.

[0026] The step S400 includes:

[0027] S401: Establishing the robot base coordinate system, the robot end measurement device coordinate system and the calibration block 5 coordinate system;

[0028] S402: The robot is kinematically modeled using the MDH method. At this time, the robot's geometric parameters a i , d i ,θ i , α i And simplify them to be nominal parameters;

[0029] S403: Obtain the pose matrix of calibration block 5 in the base coordinate system through the contact of the robot end measurement device, obtain the actual pose of the contactor of the robot end measurement device through the mechanical structure of calibration block 5, and solve the nominal pose of the robot corresponding to the joint angle of the robot at the same time, bring the above actual pose and nominal pose into the robot kinematic error model for mathematical solution to obtain the actual parameters of the robot.

[0030] The step S403 includes converting the robot error from the original robot base coordinates to the coordinates of the calibration block 5, and combining multiple sets of data measured by the robot in different planes and the original mechanical structure to establish a corresponding objective function, and seek an approximate solution with the smallest difference between a set of theoretical parameters and the actual error, so as to obtain the actual parameters of the robot.

[0031] In step S403, a series of coordinate transformations between the mechanical structure and the robot from the base to the robot tool coordinate system are calculated to obtain the calibration block 5 coordinate system {0 w X w Y w Z w} is equivalent to the nominal pose matrix of the base coordinate system {O0X0Y0Z0}:

[0032]

[0033] in α, β, γ are the clockwise rotation angles around the Z axis, Y axis, and X axis of the base coordinate system {O0X0Y0Z0}, respectively; is the position coordinate of the calibration block 5 equivalent to the robot base coordinate system;

[0034] The base coordinate system {O0X0Y0Z0} is equivalent to the calibration block 5 coordinate system {O w X w Y w Z w}'s pose matrix

[0035] Then the position coordinates of the robot end measurement device in the calibration block 5 coordinate system are expressed as

[0036] When the robot end measurement device contacts a plane of the calibration block 5, the end measurement device forms a plane constraint on the calibration block 5 and obtains the theoretical position according to the special structure of the calibration block 5 itself. and error position The corresponding data relationship;

[0037] The corresponding objective function is established to seek an approximate solution with the smallest error between the theoretical parameters and the actual parameters, so as to obtain the actual parameters of the robot.

[0038] In step S403, the coordinate system of block 5 is calibrated. w X w Y w Z w The normal vector of the top surface is Z w axis and the top surface is located at the origin of the calibration block 5 coordinate system, then the base coordinate system is equivalent to the calibration block 5 coordinate system at Z w The actual position component on the axis is 0, so when the robot end measurement device performs contact measurement on the top surface

[0039] When the robot end measuring device contacts the bevel of calibration block 5, the base coordinate system is equivalent to the calibration block 5 coordinate system in Z w The actual position component on the Z axis is y The actual position components on the axis are equal, then when the robot end measuring device performs contact measurement on the inclined surface

[0040] Similarly, the robot end measurement device is when the contact normal vector is X w When the robot end measuring device performs contact measurement on the surface, the surface is located at the origin of the coordinate system of the calibration block 5.

[0041] The robot end measurement device is in the contact normal vector Y w axis and the surface is not located at the origin of the calibration block 5 coordinate system, then the base coordinate system is equivalent to the calibration block 5 coordinate system in Y w The actual position component on the axis is a fixed value. When the robot end measurement device performs contact measurement on the surface, the position relationship between any two points i and j on the surface is:

[0042] Carry out k groups of experiments on different planes of the calibration block 5, and the following relationship can be obtained:

[0043]

[0044] A nonlinear iterative least squares algorithm is used to make the error in the objective function approach zero:

[0045]

[0046] Beneficial effects of the present invention:

[0047] (1) The present invention can complete the robot kinematic parameter calibration by only using a low-cost calibration block, which provides an effective solution for robot manufacturers to calibrate robot parameters and has a wide range of application fields and application prospects.

[0048] (2) The present invention adopts multi-plane constraints based on special calibration blocks to provide a simple and effective calibration solution for a robot with lifting joints, and the operation process is simple and does not require high professional level of the operator.

[0049] (3) The mechanical structure of the calibration block of the present invention, such as the hypotenuse with an inclination angle of 45°, makes the objective function simple. The nonlinear iterative least squares algorithm is used to make the error in the objective function tend to zero, thereby obtaining the actual parameters of the robot. After the error parameters are brought into the kinematic model for compensation, the absolute positioning accuracy is improved from 2.887 mm before calibration to 0.86 mm, and the absolute positioning accuracy of the robot end is improved by 70.2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is an overall flow chart of robot calibration using the robot calibration device of the present invention.

[0051] Figure 2 It is a structural schematic diagram of the robot calibration device of the present invention.

[0052] Figure 3 Schematic diagram of the contact between the robot end and the calibration device.

[0053] Figure 4 Schematic diagram of robot kinematic errors. DETAILED DESCRIPTION

[0054] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0055] Example 1

[0056] like Figure 2 and Figure 3 As shown, this example provides a spraying robot calibration device, including a main control and a robot connected to the main control, the main control including a robot control box and a computer system; the robot control box is used to control the movement of the robot and the measuring device, and the computer system is used to store the movement information of the robot and the measuring device;

[0057] The measuring device at the end of the robot is installed on the robot flange; the calibration block 5 is installed and fixed in the robot workspace, and the measuring device at the end of the robot can touch any position of the calibration block 5 except the bottom surface.

[0058] like Figure 1 As shown, a robot calibration method using a calibration device includes:

[0059] Step S100: Install and fix the calibration block 5 in the working space of the robot. Figure 2 As shown in the figure, a base coordinate system {O0X0Y0Z0} is established at the center of the robot base, a coordinate system {O7X7Y7Z7} is established at the end of the robot, and a workpiece coordinate system {O T X T Y T Z T}} Ensure that the x-axis and y-axis positive directions of the workpiece coordinate system and the robot end coordinate system are the same, and establish the world coordinate system at the vertex of the calibrated fast bevel. w X w Y w Z w}, providing data support for the subsequent kinematic model of robot 1.

[0060] Step S200: Utilize the dragging teaching function of robot 1 to allow the measuring device at the end of the robot to contact the vertex of calibration block 5, i.e., the origin of the world coordinate system; record the length of the lifting joint 2 at this point and the remaining joint angles, drag the measuring device at the end of the robot to make it contact the points in the positive direction of the x-axis and the positive direction of the y-axis of the world coordinate system, i.e., the vertex of calibration block 5, and record the joint angles and the length of the lifting joint 2 at the two points; connect the robot to the computer data to obtain the actual joint angles of the robot in real time and record and save them, so as to provide data support for the subsequent joint angles to be introduced into the robot kinematic model.

[0061] Step S300: Figure 3 As shown, the robot end measurement device contacts planes E1, E2, E3 and E4 respectively to perform multi-point measurements, and records the joint angles and the length of the lifting joint 2 corresponding to all points.

[0062] Step S400: Compare the nominal posture of the robot end with the actual posture, and calibrate the kinematic parameters of the robot 1. Specifically, it includes:

[0063] Step S401. Establish the robot base coordinate system {O0X0Y0Z0} and the robot end measurement device coordinate system {O T X T Y T Z T} and the calibration block 5 coordinate system, that is, the world coordinate system {O w X w Yw Z w};

[0064] S402 is to model the robot kinematics, at which point all robot parameters are nominal parameters;

[0065] S403 obtains the pose matrix of the calibration block 5 in the base coordinate system through the contact of the robot end measurement device, obtains the actual pose of the contactor of the robot end measurement device through the mechanical structure of the calibration block 5, and simultaneously solves the robot nominal pose corresponding to the robot joint angle, and brings the above actual pose and nominal pose into the robot kinematic error model for mathematical solution to obtain the actual parameters of the robot.

[0066] The coordinate system of the calibration block 5 can be obtained by calculating the mechanical structure by contacting the vertex of the hypotenuse of the calibration block 5, i.e., the base point of the world coordinate system, and the two vertices along the positive directions of the x-axis and y-axis of the world coordinate system. w X w Y w Z w} is equivalent to the nominal pose matrix of the base coordinate system {O0X0Y0Z0}:

[0067]

[0068] in α, β, γ are the clockwise rotation angles around the Z axis, Y axis, and X axis of the base coordinate system {O0X0Y0Z0}, respectively; is the position coordinate of the calibration block 5 equivalent to the robot base coordinate system;

[0069] The base coordinate system {O0X0Y0Z0} is equivalent to the calibration block 5 coordinate system {O w X w Y w Z w}'s pose matrix

[0070] Then the position coordinates of the robot end measurement device in the calibration block 5 coordinate system are expressed as:

[0071]

[0072] When the robot end measurement device contacts a plane of the calibration block 5, the end measurement device forms a plane constraint on the calibration block 5 and obtains the theoretical position according to the special structure of the calibration block 5 itself. and error position The corresponding data relationship;

[0073] The corresponding objective function is established to seek an approximate solution with the smallest error between the theoretical parameters and the actual parameters, so as to obtain the actual parameters of the robot.

[0074] Calibration block 5 coordinate system {O w X w Y w Z w The normal vector of the top surface is Z w axis and the top surface is located at the origin of the calibration block 5 coordinate system, then the base coordinate system is equivalent to the calibration block 5 coordinate system at Z w The actual position component on the axis is 0, so when the robot end measurement device performs contact measurement on the top surface:

[0075]

[0076] When the robot end measuring device contacts the bevel of calibration block 5, the base coordinate system is equivalent to the calibration block 5 coordinate system in Z w The actual position component on the Z axis is y The actual position components on the axis are equal, then when the robot end measuring device performs contact measurement on the inclined surface:

[0077]

[0078] Similarly, the robot end measurement device is when the contact normal vector is X w When the robot end measuring device performs contact measurement on the surface, the surface is located at the origin of the coordinate system of the calibration block 5.

[0079] The robot end measurement device is in the contact normal vector Y w axis and the surface is not located at the origin of the calibration block 5 coordinate system, then the base coordinate system is equivalent to the calibration block 5 coordinate system in Y w The actual position component on the axis is a fixed value. When the robot end measurement device performs contact measurement on the surface, the position relationship between any two points i and j on the surface is:

[0080]

[0081] Carry out k groups of experiments on different planes of the calibration block 5, and the following relationship can be obtained:

[0082]

[0083] A nonlinear iterative least squares algorithm is used to make the error in the objective function approach zero:

[0084]

[0085] The final absolute positioning accuracy was reduced from 2.887mm to 0.848mm, and the error was improved by 70.2%.

Claims

1. A spraying robot calibration device, characterized in that: It includes a main control and a robot. The main control includes a robot control box and a computer system. The robot control box and the computer system are connected to the robot. A measuring device is set at the end of the robot through a flange. The robot control box is used to control the movement of the robot and the measuring device. The computer system is used to store the movement information of the robot and the measuring device. The robot comprises a base joint (1), a lifting joint (2) and a six-degree-of-freedom mechanical arm (3), wherein the base joint (1) is connected to the six-degree-of-freedom mechanical arm (3) via the lifting joint (2); The measuring device comprises a metal probe (4) having the same size as the end of the robot and a calibration block (5) with an inclined surface, wherein the metal probe (4) is mounted on the end of a six-degree-of-freedom mechanical arm (3), and the calibration block (5) contacts the calibration plane through the end of the robot; The measuring device obtains the position and posture transformation of the calibration block (5) relative to the robot base coordinates by contacting the vertices of the sloped edge of the calibration block (5) with the metal probe (4).

2. A spraying robot calibration device according to claim 1, characterized in that: The robot performs contact measurement on a vertex of the hypotenuse of the calibration block (5) to form a limit position that limits the movement of the robot end and the lifting joint (2), and obtains a coordinate transformation matrix based on the robot base coordinate system, that is, the nominal posture of the robot is obtained based on the robot joint angle at the limit position and the length of the lifting joint (2), and the minimum error between the nominal posture and the actual posture is solved to realize the calibration of the spraying robot.

3. A spraying robot calibration device according to claim 2, characterized in that: The calibration block (5) is a trapezoid, with an inclined plane at an angle of 45°. The top surface size of the other five planes is 200x200mm, and the size of the inclined plane relative to the top surface is the same. The lower base of the two adjacent trapezoids is 400mm, the upper base is 200mm, the height is 200mm, and the bottom surface size is 200mmx400mm. The above five planes are perpendicular to each other except the opposite plane.

4. A calibration method for a spraying robot calibration device according to any one of claim 3, characterized in that: The following steps are involved: S100: The calibration block (5) is placed in a workspace reachable by the robot end and fixed; a coordinate system is established; S200: Using the teaching pendant, the end of the robot is brought into contact with the top point of the bevel of the calibration block (5), and the length of the robot lifting joint (2) and the angles of the other joints at that point are recorded; S300: Using a dragging teaching method, the robot end measurement tool is allowed to contact three mutually perpendicular planes and an inclined plane of the calibration block (5), and multiple groups of point measurements are performed respectively, and then the corresponding robot nominal theoretical posture, i.e., the length of the robot lifting joint (2) and the remaining joint angles are recorded; S400: Compare the error between the nominal position of the robot end and the actual position based on the mechanical structure of the calibration block (5), and calibrate the robot kinematic parameters.

5. A method for calibrating a spraying robot according to claim 4, characterized in that: The step S100 includes establishing a base coordinate system {00X0Y0Z0} at the center of the robot base, and establishing a tool coordinate system {00X0Y0Z0} on the robot end measurement device. T X T Y T Z T }, establish the world coordinate system {O w X w Y w Z w }; The robot tool is calibrated through the robot base coordinate system {O0X0Y0Z0}} to the position and posture relationship of the robot end, and the robot tool coordinate system {O T X T Y T Z T }, the pose transformation and position of the robot tool end in the robot base coordinates can be obtained.

6. A method for calibrating a spraying robot according to claim 4, characterized in that: The step S200 includes: the robot end tool contacts the vertex of the inclined surface of the calibration block (5) to obtain the base coordinate system {O0X0Y0Z0} to the world coordinate system {O w X w Y w Z w } coordinate transformation, connect the robot with a computer, obtain the length of the robot's lifting joint (2) and the angles of the other joints and record them, establish a kinematic model through the MDH method, and substitute the recorded data to obtain the coordinate transformation from the base coordinate to the world coordinate.

7. A method for calibrating a spraying robot according to claim 4, characterized in that: In the above S300, the specific operation measurement method of dragging teaching is to allow the robot end measurement tool to contact the calibration block (5) plane to perform multiple point measurements. After seeing that the robot end measurement tool contacts the calibration block (5) plane, the corresponding robot lifting joint (2) length and other joint angles are recorded to obtain the nominal theoretical position of the robot on the calibration block (5).

8. A method for calibrating a spraying robot according to claim 4, characterized in that: The step S400 includes: S401: Establishing the robot base coordinate system, the robot end measurement device coordinate system and the calibration block (5) coordinate system; S402: Use the MDH method to perform kinematic modeling on the robot. The geometric parameters a of the robot i , d i ,θ i , α i And simplify them to be nominal parameters; S403: The pose matrix of the calibration block (5) in the base coordinate system is obtained through the contact of the robot end measurement device, and the actual pose of the contactor of the robot end measurement device is obtained through the mechanical structure of the calibration block (5). At the same time, the nominal pose of the robot corresponding to the joint angle of the robot is solved, and the above actual pose and nominal pose are brought into the robot kinematic error model for mathematical solution to obtain the actual parameters of the robot.

9. A method for calibrating a spraying robot according to claim 8, characterized in that: The step S403 includes converting the robot error from the original robot base coordinates to the coordinates of the calibration block (5), and establishing a corresponding objective function by combining multiple sets of data measured by the robot in different planes and the original mechanical structure, and seeking an approximate solution with the smallest difference between a set of theoretical parameters and the actual error, thereby obtaining the actual parameters of the robot; In step S403, a series of coordinate transformations between the mechanical structure and the robot from the base to the robot tool coordinate system are calculated to obtain the calibration block (5) coordinate system {0 w X w Y w Z w } is equivalent to the nominal pose matrix of the base coordinate system {O0X0Y0Z0}: in α, β, γ are the clockwise rotation angles around the Z axis, Y axis, and X axis of the base coordinate system {O0X0Y0Z0}, respectively; is the position coordinate of the calibration block (5) equivalent to the robot base coordinate system; Then the base coordinate system {O0X0Y0Z0}} is equivalent to the calibration block (5) coordinate system {O w X w Y w Z w }}'s pose matrix Then the position coordinates of the robot end measurement device in the calibration block (5) coordinate system are expressed as When the robot end measurement device contacts a certain plane of the calibration block (5), the end measurement device forms a plane constraint on the calibration block (5) to obtain a theoretical position and error position The corresponding data relationship; The corresponding objective function is established to seek an approximate solution with the smallest error between the theoretical parameters and the actual parameters, so as to obtain the actual parameters of the robot.

10. A method for calibrating a spraying robot according to claim 9, characterized in that: In step S403, the coordinate system of the calibration block (5) {O w X w Y w Z w The normal vector of the top surface is Z w axis and the top surface is located at the origin of the coordinate system of the calibration block (5), then the base coordinate system is equivalent to the coordinate system of the calibration block (5) in Z w The actual position component on the axis is 0, so when the robot end measurement device performs contact measurement on the top surface When the robot end measuring device contacts the bevel of the calibration block (5), the base coordinate system is equivalent to the coordinate system of the calibration block (5) in Z w The actual position component on the Z axis is y The actual position components on the axis are equal, then when the robot end measuring device performs contact measurement on the inclined surface Similarly, the robot end measurement device is when the contact normal vector is X w When the robot end measuring device performs contact measurement on the surface, the surface is located at the origin of the coordinate system of the calibration block (5). The robot end measurement device is in the contact normal vector Y w axis and the surface is not located at the origin of the calibration block (5) coordinate system, then the base coordinate system is equivalent to the calibration block (5) coordinate system in Y w The actual position component on the axis is a fixed value. When the robot end measurement device performs contact measurement on the surface, the position relationship between any two points i and j on the surface is: Carry out k groups of experiments on different planes of the calibration block (5) and obtain the following relationship: A nonlinear iterative least squares algorithm is used to make the error in the objective function approach zero:

Images