Robot sand belt tool tcp calibration method and device based on pressure-laser cooperation

Abstract

The present application relates to the technical field of robot abrasive belt tool calibration, and particularly relates to a robot abrasive belt tool TCP calibration method and device based on pressure-laser cooperation, a measurement coordinate system coaxial with a base coordinate system of a robot device is established through a laser tracker, contact wheel pressure data is collected by a pressure distribution collector, and a tool zero attitude is calibrated; then the geometric parameters of the contact wheel and the flange are fitted through laser, the pose relationship of the tool coordinate system relative to the flange coordinate system is calculated, and TCP calibration is completed. The problems of low pose calibration accuracy, uncalibrated zero attitude and deviated results from the real working state caused by assembly and manufacturing errors are solved, and the present application is suitable for high-precision machining scenes. The problems of low pose calibration accuracy, uncalibrated zero attitude and deviated results from the real working state caused by tool assembly and manufacturing errors are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of robot abrasive belt tool calibration, and particularly relates to a robot abrasive belt tool TCP calibration method and device based on pressure-laser cooperation. BACKGROUND

[0002] Robot abrasive belt processing technology is a core processing technology in the field of precision manufacturing. The processing technology has the advantages of high removal rate, strong controllability of removal rate, and covering the whole process of grinding and polishing. The abrasive belt processing tool is rigidly connected with the end flange of the robot. The pose, feed speed and contact pressure of the tool are controlled by the robot program to flexibly perform processing tasks of different materials (metal, composite material, optical element, etc.).

[0003] For the field of high-precision manufacturing such as optical processing, how to accurately calibrate the TCP of the abrasive belt processing equipment directly determines the processing precision. At present, there are mainly two types of existing TCP calibration methods: four-point calibration and single non-contact laser tracker calibration scheme. The four-point calibration method controls the robot to move the tool end with a needle-shaped object to different poses at predetermined spatial positions and makes four contacts to complete the calculation of the TCP. However, this method relies too much on manual operation and has low calibration accuracy. The single non-contact laser tracker calibration scheme uses the high-precision coordinate measurement capability of the laser tracker to fit the geometric characteristics of the processing tool to indirectly solve the position and attitude parameters of the TCP. However, this method ignores the tool assembly and manufacturing errors, has insufficient real attitude calibration, cannot calibrate the theoretical zero attitude deviation, relies too much on the ideal tool state, and thus makes the TCP attitude calibration result deviate from the real working state. SUMMARY

[0004] Therefore, the present application aims to provide a robot abrasive belt tool TCP calibration method and device based on pressure-laser cooperation to solve the problem of low attitude calibration accuracy, inability to calibrate the zero attitude, and deviation of the TCP attitude calibration result from the real working state caused by tool assembly and manufacturing errors.

[0005] To achieve the above-mentioned purpose, the technical solution of the present application is as follows:

[0006] The first aspect of the present application provides a robot abrasive belt tool TCP calibration method based on pressure-laser cooperation, comprising the following steps:

[0007] S1, input the theoretical parameters of the robot device end contact wheel relative to the center point of the flange plate, adjust the device to the theoretical zero attitude; the flange plate side cylindrical surface is placed with a target ball, the device is driven to move along the X, Y, Z axes of its base coordinate system, the target ball coordinates of the laser tracker are recorded, and the measurement coordinate system is fitted and made consistent with the coordinate axes of the base coordinate system of the device;

[0008] S2, place the pressure distribution collector on the upper surface of the optical element to be processed, keep the zero attitude, drive the device to move above the pressure distribution collector and contact, save the pressure matrix data and record the current Z axis position;

[0009] S3, rotate the six-axis device, press down to the Z axis position of step S2 and record the pressure data, collect data within the range of ±3° of the six-axis, calculate the center of gravity coordinates of the contact area and the normalized deviation, adjust according to the sixth axis adjustment formula, and lock the six-axis angle when the normalized deviation is ≤0.02;

[0010] S4, rotate the one-axis device, repeat the pressing down and data collection of step S3, collect data within the range of ±3° of the one-axis, calculate the second moment and the rotational direction asymmetry, adjust according to the first axis adjustment formula, and record the Euler angle when the asymmetry is <0.03, calculate the rotation matrix of the flange coordinate system relative to the base coordinate system;

[0011] S5, adsorb the target ball on the side surface of the contact wheel, measure at least four position coordinates, fit the side surface normal and normalize to get the X-axis direction vector of the tool coordinate system, construct the tool coordinate system combined with the Z-axis of the base coordinate system and the right-hand rule, calculate the rotation matrix of the tool coordinate system relative to the flange coordinate system and convert it into a quaternion input to the teach pendant, complete the attitude calibration;

[0012] S6, place the target ball on the outer surface of the contact wheel, measure at least four position coordinates and fit to get the center point and radius, determine the lowest point coordinate of the contact wheel coordinate of the flange plate center point relative position and input the teach pendant translation value, complete the position calibration.

[0013] Further, in step S3, the contact area center of gravity coordinate calculation formula is:

[0014] ,

[0015] ;

[0016] wherein, is the pressure value at the point in the pressure distribution collector coordinate system, indicates the first iRow j the coordinate value of the pixel point in the X-axis direction of the coordinate system of the pressure distribution collector, the coordinate value of the pixel point in the Y-axis direction of the coordinate system of the pressure distribution collector, i Row j the coordinate value of the pixel point in the Y-axis direction of the coordinate system of the pressure distribution collector;

[0017] The calculation formula of the normalized deviation is:

[0018] ;

[0019] The sixth axis adjustment formula is:

[0020] ;

[0021] wherein, the coordinate value of the pressure center of the contact area of the contact wheel and the pressure distribution collector in the X-axis direction of the coordinate system of the pressure distribution collector under different contact angles, the coordinate value of the pressure center of the contact area of the contact wheel and the pressure distribution collector in the Y-axis direction of the coordinate system of the pressure distribution collector under different contact angles, and a is the length of the major axis of the pressure distribution ellipse, is the theoretical center position of the contact area.

[0022] Further, in step S4, the second moment calculation formula is:

[0023] ,

[0024] ,

[0025] ,

[0026] wherein, represents the dispersion degree of the pressure distribution along the X-axis direction of the base coordinate system, represents the dispersion degree of the pressure distribution along the Y-axis direction of the base coordinate system, represents the deviation degree of the major axis of the pressure distribution ellipse from the coordinate axis;

[0027] The first axis adjustment formula is:

[0028] ,

[0029] wherein, represents the first axis angle adjustment amount of the robot device; represents the dispersion degree difference of the pressure distribution in the X-axis direction and the Y-axis direction of the base coordinate system;

[0030] Rotation direction asymmetry The formula is:

[0031] ,

[0032] wherein, represents the degree of inclination of the pressure distribution from the coordinate axis in the X-Y plane, represents the total dispersion of the pressure distribution relative to the center of gravity.

[0033] Further, in step S4, the flange coordinate system relative to the base coordinate system rotation matrix calculation formula is:

[0034] ,

[0035] ,

[0036] ,

[0037] ,

[0038] wherein, respectively represent the rotation angle of the current flange coordinate system around the Z axis, Y axis and X axis of the base coordinate system, then is the rotation matrix around the X axis, is the rotation matrix around the Y axis, is the rotation matrix around the Z axis.

[0039] Further, in step S5, the formula for obtaining the normal of the surface on which the measurement points are located by least squares fitting is:

[0040]

[0041] wherein, represents the three-dimensional coordinates of a measurement point on the side surface of the contact wheel, , , represents the normal vector component of the fitted contact wheel side surface plane; represents the three-dimensional coordinate variable of any point on the normal line;

[0042] Contact wheel side surface normal vector The formula is:

[0043] ;

[0044] , is normalized to a unit vector The formula is:

[0045] ,

[0046] The rotation matrix to quaternion formula is:

[0047] ,

[0048] wherein, , , , , , , , , are elements of the rotation matrix of the tool coordinate system relative to the flange coordinate system; represents the scalar part of the quaternion, which is related to the rotation angle, , , represents the vector part of the quaternion, which is related to the rotation axis direction.

[0049] Further, in step S6, the lowest point of the contact wheel The coordinate formula is:

[0050]

[0051] wherein, represents the three-dimensional coordinates of the center point of the contact wheel in the measurement coordinate system; represents the actual radius of the contact wheel; represents the z-coordinate of the lowest point

[0052] The coordinate formula of the center point of the flange plate is:

[0053] ,

[0054] wherein, , represent the X-axis and Z-axis coordinates of the "flange side surface cylindrical surface center" fitted by the laser tracker in the measurement coordinate system; represents the Y-axis coordinate in the measurement coordinate system when the target ball is placed at the "flange and adapter plate intersection center position"; represents the standard radius of the target ball used by the laser tracker;

[0055] The position amount formula of the lowest point of the contact wheel relative to the center point of the flange plate is:

[0056] .

[0057] ​The second aspect of the present application provides a robot abrasive belt tool TCP calibration device based on pressure-laser cooperation, a robot abrasive belt tool TCP calibration method based on pressure-laser cooperation according to any one of the above-mentioned first aspect, comprising:

[0058] A robot device is provided with a flange, and an abrasive belt tool module is connected to the flange, the abrasive belt tool module comprising a contact wheel, the outer ring of the contact wheel abutting the surface of an optical element to be machined;

[0059] A pressure distribution collector is arranged on the surface of the optical element to be machined, for collecting pressure matrix data when the contact wheel contacts the pressure distribution collector, and calculating the barycentric coordinates, second moment and normalized deviation of the pressure distribution;

[0060] A laser measurement module comprising a laser tracker and a target ball, the target ball being arranged on the flange, and the laser tracker being arranged on one side of the optical element to be machined, for measuring the three-dimensional coordinates of the target ball in a measurement coordinate system, and fitting to obtain the center point, radius, side surface normal and flange center point of the contact wheel.

[0061] Further, an adapter plate is arranged on the abrasive belt tool module, and the flange is connected to the abrasive belt tool module through the adapter plate.

[0062] Compared with the prior art, the present application can achieve the following beneficial effects:

[0063] A measurement coordinate system coaxial with the base coordinate system of the robot device is established by the laser tracker, ensuring that the measurement reference is consistent with the motion reference of the robot device; then the pressure data under different contact angles are collected by the pressure distribution collector, the barycentric coordinates, second moment and asymmetry are calculated, the tool theoretical zero attitude is accurately calibrated, and the problem of deviation of the tool lowest point caused by machining and assembly errors is avoided; finally, the contact wheel normal line, center point and flange center point are fitted by the laser tracker, the pose relationship between the tool coordinate system and the flange coordinate system is constructed, and the double calibration of TCP attitude and position is completed. The problems of low attitude calibration accuracy, inability to calibrate the zero attitude, and deviation of the TCP attitude calibration result from the real working state caused by tool assembly and manufacturing errors are solved. BRIEF DESCRIPTION OF DRAWINGS

[0064] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0065] Figure 1A flow chart of a robot abrasive belt tool TCP calibration method based on pressure-laser cooperation provided by an embodiment of the present application is shown in the figure.

[0066] Figure 2 A schematic diagram of the overall structure of a robot abrasive belt tool TCP calibration device based on pressure-laser cooperation provided by an embodiment of the present application is shown in the figure.

[0067] Figure 3 A schematic diagram of the structure of an abrasive belt tool module provided by an embodiment of the present application is shown in the figure.

[0068] Explanation of reference signs:

[0069] 1, robot device; 2, flange; 3, abrasive belt tool module; 4, contact wheel; 5, optical element to be processed; 6, pressure distribution collector; 7, laser tracker; 8, target ball; 9, adapter plate; 10, marble experiment platform. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and do not constitute a limitation on the present application. Similar elements in different embodiments use associated similar element numbers. In the following embodiments, many details are described in order to make the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different cases, or can be replaced by other elements, materials or methods. In some cases, some operations related to the present application are not shown or described in the specification in order to avoid the core part of the present application being overwhelmed by too much description, and it is not necessary to describe these related operations in detail for those skilled in the art based on the description in the specification and general technical knowledge in the art.

[0071] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other to form various embodiments without conflict. Meanwhile, the steps or actions in the method description can also be sequentially adjusted or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment, and do not mean a necessary sequence, unless otherwise stated that a certain sequence must be followed.

[0072] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise stated, the meaning of "a plurality of" is two or more.

[0073] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0074] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0075] As Figure 1 shown, the first aspect of the present embodiment provides a robot abrasive belt tool TCP calibration method based on pressure-laser cooperation, comprising the following steps:

[0076] S1, according to the theoretical geometric parameters and attitude parameters of the robot device 1 end contact wheel 4 working point relative to the center point of the flange plate 2, input the teaching device, and adjust the robot device 1 end attitude to the theoretical zero position attitude; Place the target ball 8 on the side cylindrical surface of the flange plate 2, drive the robot device to move along the axis of its base coordinate system {B} respectively, while recording the point coordinates of the target ball at different positions of the laser tracker, fitting the axis of the measurement coordinate system {M}, so that the coordinate axes of the measurement coordinate system {M} are the same as the coordinate axes of the base coordinate system {B} of the robot device.

[0077] In this embodiment, the robot device 1 adopts a six-axis robot. First, according to the theoretical geometric parameters and attitude parameters of the contact wheel 4 working point at the end of the robot device 1 relative to the center point of the flange 2, the contact wheel 4 initial pose reference is determined by inputting the parameters into the teach pendant, and the end pose of the robot device 1 is adjusted to the theoretical zero pose, so that the contact wheel 4 is in the design and processing state from the calibration start, and the efficiency is not reduced due to the large initial attitude deviation in subsequent calibration. Then, the target ball 8 is placed on the cylindrical surface of the flange 2, and the robot device 1 is driven to move along the coordinate system {B} of the robot device 1 respectively axis, and the point coordinates of the target ball 8 at different positions of each coordinate axis of the laser tracker 7 are recorded, and the coordinate axes of the measurement coordinate system {M} are fitted axis, so that the coordinate axes of the measurement coordinate system {M} are the same as the coordinate axes of the base coordinate system {B} of the robot device. The conversion error between different coordinate systems is eliminated, the consistency and reliability of all calibration data are ensured, and the TCP calibration deviation caused by the reference misalignment is avoided.

[0078] S2, the pressure distribution collector 6 is placed on the upper surface of the optical element 5 to be processed, so that the coordinate system of the pressure distribution collector 6 is the same as the measurement coordinate system {M}; under the condition of maintaining the theoretical zero attitude, the robot device 1 is driven to move linearly above the pressure distribution collector 6, the robot device 1 is moved so that the contact wheel 4 contacts the pressure distribution collector 6, the pressure matrix data in the pressure distribution collector 6 is saved, and the current axis position is recorded.

[0079] By placing the pressure distribution collector 6 on the surface of the optical element 5 to be processed above the marble experimental platform 10, and making the coordinate system of the pressure distribution collector 6 the same as the measurement coordinate system {M}, the spatial reference of pressure data collection is completely consistent with the laser measurement reference, and the coordinate system of "pressure feedback" and "laser positioning" is realized, which provides a precise data correlation basis for subsequent calibration of the contact wheel 4 attitude through the pressure distribution characteristics. At the same time, under the condition of maintaining the theoretical zero attitude, the robot device 1 is driven to move linearly above the pressure distribution collector 6, and then the robot device 1 is moved so that the contact wheel 4 contacts the pressure distribution collector 6, the pressure matrix data in the pressure distribution collector 6 is saved, and the current Z axis position is recorded. On the one hand, the initial pressure distribution characteristics of the contact wheel 4 in contact with the optical element 5 to be processed are obtained, and on the other hand, the contact depth in the Z axis direction is locked, so that the contact pressure between the contact wheel 4 and the pressure distribution collector 6 remains stable when the axis angle of the robot device 1 is adjusted subsequently, and the accuracy of attitude calibration is not affected by the change of pressure, thereby laying a unified and controllable contact state foundation for accurate calibration of the zero attitude.

[0080] ​S3, rotate the six-axis of the robot device 1 slowly, each time by 0.5°, press the robot device 1 down to the current position recorded in step S2, record the data in the pressure distribution collector 6, repeat this step, collect the pressure distribution data in the range of ±3° under the theoretical zero position, calculate the barycentric coordinates of the contact area under different contact angles

[0081]

[0082]

[0083] Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6, Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6, Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6, i Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6, j Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6, Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6, i Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6, j Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6.

[0084]

[0085]

[0086]

[0087]

[0088] Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6, Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6, Pij is the pressure value at the coordinate (i, j) in the coordinate system of the pressure distribution collector 6.

[0089]

[0090] ​​​​​​​​​​​​​​By controlling the robot device 1 to rotate in small steps within a range of ±3° and repeatedly press down to the fixed axis position, the pressure distribution data at different contact angles can be comprehensively collected, and the contact pressure state is consistent with the reference in step S2 each time, avoiding the interference of pressure fluctuation on data effectiveness; then the discrete pressure matrix data is converted into quantified pressure center position through the gravity coordinate, and the normalized deviation eliminates the influence of the size difference of the pressure distribution ellipse, and accurately quantifies the deviation degree of the pressure gravity center and the theoretical center. This process realizes the mathematical conversion from “pressure distribution characteristics” to “attitude deviation”, making the horizontal direction attitude error, which is originally difficult to intuitively judge, become calculable and adjustable.

[0091] At the same time, based on and the difference between the sixth axis rotation direction, through the sixth axis adjustment formula give specific adjustment basis, ensure that each axis angle adjustment has data support, avoid blind operation; finally take as the calibration termination condition, from the quantitative point of view, ensure that the horizontal direction pressure distribution symmetry meets the standard, effectively correct the horizontal direction attitude deviation caused by tool assembly deviation, lock the sixth axis angle that meets the actual contact state, provide accurate horizontal attitude reference for subsequent rotation direction calibration and TCP attitude calibration.

[0092] S4, slowly rotate one axis of the robot device 1, each time by 0.5°, press down the robot device 1 to the axis position recorded in step S2, record the data in the pressure distribution collector 6, repeat this step to collect the pressure distribution data within ±3° of the theoretical zero attitude, calculate the second moment to obtain the rotation angle of the pressure distribution ellipse relative to the coordinate axis, then the second moment calculation formula is:

[0093] ,

[0094] ,

[0095] ,

[0096] wherein, represents the dispersion degree of the pressure distribution along the axis direction of the base coordinate system, represents the dispersion degree of the pressure distribution along the axis direction of the base coordinate system, represents the deviation degree of the major axis of the pressure distribution ellipse from the coordinate axis.

[0097] Then define the first axis adjustment formula, then:

[0098] ,

[0099] in, This represents the adjustment amount of the first axis angle of robot device 1; Represents the pressure distribution in the base coordinate system Axial direction and Differences in the degree of dispersion along the axial direction.

[0100] like Rotate the axis counterclockwise, if Rotate the axis clockwise.

[0101] Calculate rotational asymmetry ,but:

[0102] ,

[0103] in, This represents the degree of inclination of the pressure distribution off the coordinate axes in the XY plane. It represents the overall dispersion of pressure distribution relative to the center of gravity.

[0104] When the rotation direction is asymmetrical At that time, record the Euler angles in the teach pendant under the current posture. Calculate the rotation matrix of the flange coordinate system relative to the base coordinate system {B}. .

[0105] In some embodiments, the rotation matrix of the flange coordinate system relative to the base coordinate system {B} in step S4 The calculation formula is:

[0106] ,

[0107] ,

[0108] ,

[0109] ,

[0110] but,

[0111]

[0112] in, These represent the current flange coordinate system's coordinates relative to the base coordinate system {B}. axis, axis, The rotation angle of the axis, then To bypass Axis rotation matrix, To bypass Axis rotation matrix, for rotating the robot device 1 around an axis. matrix of rotation around an axis.

[0113] by controlling the robot device 1 to rotate in small steps within a range of ±3° around an axis and to keep the axis pressed down, pressure distribution data in different attitudes of the rotating direction can be comprehensively collected under the premise of stable contact pressure, avoiding the interference of pressure changes on the attitude calibration of the rotating direction; and the pressure distribution data is converted into quantified dispersion parameters by the second moment formula , accurately capturing the inclination and dispersion difference of the pressure distribution ellipse. Among them, directly reflects the deviation degree of the major axis of the ellipse and the coordinate axis, and the difference between them reflects the dispersion difference of the two axes, providing a mathematical quantitative basis for the attitude error of the rotating direction. The first axis adjustment formula derived based on the second moment can clearly determine the rotating direction according to the positive and negative of , so that the axis angle adjustment has accurate data support and avoids blind operation. Taking as the calibration termination condition, the symmetry of the pressure distribution in the rotating direction is ensured to meet the standard from the quantitative point of view, effectively correcting the attitude deviation of the rotating direction caused by tool manufacturing deviation or assembly deviation, and locking the axis angle that meets the actual machining contact state. Finally, by recording the Euler angle and calculating the rotation matrix of the flange coordinate system relative to the base coordinate system, the attitude of the calibrated flange plate 2 is converted into a mathematical model that can be recognized by the robot device 1, providing a key flange attitude reference for subsequent construction of the pose relationship between the tool coordinate system {T} and the flange coordinate system, and completing the TCP attitude calibration, ensuring the accurate quantification of the attitude calibration.

[0114] S5, adsorb the target ball 8 on the side surface of the contact wheel 4, slowly rotate the contact wheel 4, and measure the coordinates of the target ball 8 at least at four different positions, and use least squares fitting to obtain the normal line of the plane where the measurement points are located , which can be expressed as:

[0115] ,

[0116] Among them, , , represents the three-dimensional coordinates of a measurement point on the side surface of the contact wheel 4, , , represent the normal vector components of the plane where the contact wheel 4 is located; , , represent the three-dimensional coordinate variables of any point on the normal line;

[0117] Determining the contact wheel 4 side surface normal vector Then:

[0118] ;

[0119] The is normalized to a unit vector Then:

[0120] ;

[0121] The unit vector is the direction vector of the axis of the tool coordinate system {T} in the base coordinate system {B} That is, ;

[0122] The direction vector of the axis of the tool coordinate system {T} is consistent with the axis of the base coordinate system {B}, then: According to the right-hand coordinate system rule, the direction of the Y-axis is obtained by the cross product of the direction vector of the axis and the direction vector of the axis , then:

[0123]

[0124] Where, respectively represent the unit base vectors of the , , axis of the base coordinate system {B}.

[0125] The rotation matrix of the tool coordinate system {T} relative to the base coordinate system {B} is constructed Then:

[0126]

[0127] Then the rotation matrix of the tool coordinate system {T} relative to the flange coordinate system is calculated from the chain relationship of the rotation matrix Then:

[0128] Convert it to the quaternion of the robot device 1 demonstrator and input it into the robot device 1 demonstrator, complete the pose calibration of the TCP, and the rotation matrix to quaternion formula is:

[0129]

[0130] ​​​ ,

[0131] in, , , , , , , , , These are the elements of the rotation matrix of the tool coordinate system {T} relative to the flange coordinate system; The scalar part representing the quaternion is related to the rotation angle. , , The vector part representing the quaternion is related to the direction of the rotation axis.

[0132] By adsorbing the target ball 8 onto the side surface of the contact wheel 4 and measuring the coordinates at multiple positions, combined with least squares fitting of the normal line... It can determine the side surface normal vector based on the actual geometry of contact wheel 4. To avoid deviations in the normal vector caused by relying on theoretical design parameters, and to ensure the accuracy of the tool coordinate system {T}. The axial direction is consistent with the actual structure of contact wheel 4; the normal vector is normalized to a unit vector. This eliminates the interference of vector length on direction determination and accurately defines the tool coordinate system {T}. The direction of the axis in the base coordinate system {B}. The axis is the Z-axis of the tool coordinate system {T}, obtained by cross product using the right-hand rule. In the axial direction, the constructed tool coordinate system {T} can completely and accurately reflect the actual posture of the tool, providing a reliable tool reference for subsequent pose transformation; then, through the chain relationship of rotation matrices... The tool's attitude relative to the base coordinate system {B} is transformed into its attitude relative to the flange coordinate system, achieving precise quantification of the "tool and flange" pose association and solving the attitude transmission deviation problem caused by assembly errors between the tool and flange. Finally, the rotation matrix is ​​converted into a quaternion that the robot device 1 teach pendant can recognize. This avoids the gimbal lock problem that is prone to occur with rotation matrices and conforms to the attitude parameter input specifications of the robot device 1 control system, ensuring that the calibrated tool attitude can be accurately imported into the system. Ultimately, TCP attitude calibration that conforms to the actual structure and assembly state of the tool is completed, providing a guarantee for precise control of the tool attitude during subsequent processing.

[0133] S6. Place the target ball 8 at at least four different positions on the outer surface of the contact wheel 4. Use the laser tracker 7 to measure the coordinates of the target ball 8 at different positions. Calculate the center point of the contact wheel 4 using the fitting ball function of the laser tracker 7. and the actual radius of contact wheel 4 determining the coordinates of the lowest point of the contact wheel 4, then:

[0134]

[0135] wherein, represents the three-dimensional coordinates of the center point of the contact wheel 4 in the measuring coordinate system {M}; represents the actual radius of the contact wheel 4; represents the z-coordinate of the lowest point of the contact wheel 4.

[0136] Place the target ball 8 on the side surface cylinder of the flange plate 2 and fix it, rotate the sixth axis at the end of the robot device 1, measure the coordinates of the target ball 8 at different positions in the measuring coordinate system {M}, and the number of measurement points is not less than four points, and the coordinates of the center point of the circle where the target ball 8 is located are determined by using the ball fitting function of the laser tracker 7. Place the target ball 8 near the center position of the intersection surface between the flange plate 2 and the adapter plate, and measure the position coordinates of the target ball 8 at this time Calculate the coordinates of the center point of the flange plate 2 , then:

[0137] ,

[0138] wherein, , represents the x-axis and y-axis coordinates of the "center of the side surface cylinder of the flange plate 2" fitted by the laser tracker 7 in the measuring coordinate system {M}; represents the x-axis and y-axis coordinates of the "center of the side surface cylinder of the flange plate 2" fitted by the laser tracker 7 in the measuring coordinate system {M}; represents the x-axis and y-axis coordinates of the "center of the side surface cylinder of the flange plate 2" fitted by the laser tracker 7 in the measuring coordinate system {M}; represents the x-axis and y-axis coordinates of the "center of the side surface cylinder of the flange plate 2" fitted by the laser tracker 7 in the measuring coordinate system {M}; represents the x-axis and y-axis coordinates of the "center of the side surface cylinder of the flange plate 2" fitted by the laser tracker 7 in the measuring coordinate system {M}; represents the standard radius of the target ball 8 used by the laser tracker 7.

[0139] Calculate the position amount of the lowest point of the contact wheel 4 relative to the center point of the flange plate 2 , then:

[0140] ,

[0141] Input the position amount into the translation value in the teach pendant of the robot device 1, and complete the position calibration of the TCP.

[0142] ​​​The actual center point and radius of the contact wheel 4 can be directly obtained (instead of relying on the design value), the influence of the manufacturing error (such as diameter deviation) of the contact wheel 4 on the calculation of the lowest point is effectively eliminated, and the authenticity of the coordinates of the TCP core action point (the lowest point of the contact wheel 4 T ) is ensured; and the flange center point is accurately positioned by fitting the center of the flange 2 side cylindrical surface and the intersection center of the target ball 8, combined with the correction of the target ball 8 radius P , the reference offset problem caused by the assembly deviation of the flange and the adapter plate is solved, and the flange reference is matched with the actual structure state. Then, the position amount T relative to P is calculated , and the position amount is finally input into the teaching value, so that the robot device 1 can accurately identify the position of the TCP relative to the flange 2, and ensure the positioning accuracy of the robot device 1 to the action point of the contact wheel 4 in subsequent processing, and meet the demand that the TCP position is completely matched with the actual working state in the high-precision processing scene.

[0143] Through the above technical scheme, the measurement coordinate system {M} coaxial with the base coordinate system {B} is established by the laser tracker 7, so that the measurement reference is consistent with the motion reference of the robot device 1; then the pressure data under different contact angles are collected by the pressure distribution collector 6, the center of gravity coordinates, the second moment and the asymmetry are calculated, the tool theoretical zero attitude is accurately calibrated, and the problem of deviation of the tool lowest point caused by the machining and assembly error is avoided; finally, the normal line of the contact wheel 4, the center point and the center point of the flange 2 are fitted by the laser tracker 7, the pose relationship between the tool coordinate system {T} and the flange coordinate system is constructed, and the TCP pose and position double calibration are completed. The problems of low pose calibration accuracy, unable to calibrate the zero attitude, and further deviation of the TCP pose calibration result from the real working state caused by the tool assembly and manufacturing error are solved.

[0144] The second aspect of the present application provides a robot abrasive belt tool TCP calibration device based on pressure-laser cooperation, a robot abrasive belt tool TCP calibration method based on pressure-laser cooperation according to any one of the above-mentioned first aspect, comprising a robot device 1, a pressure distribution collector 6 and a laser measurement module, the robot device 1 is provided with a flange plate 2, the flange plate 2 is connected with an abrasive belt tool module 3, the abrasive belt tool module 3 comprises a contact wheel 4, the outer ring of the contact wheel 4 abuts against the surface of a to-be-processed optical element 5. The pressure distribution collector 6 is arranged on the surface of the to-be-processed optical element 5, for collecting pressure matrix data when the contact wheel 4 contacts the pressure distribution collector 6, and calculating the gravity center coordinates, the second moment and the normalized deviation of the pressure distribution. The laser measurement module comprises a laser tracker 7 and a target ball 8, the target ball 8 is arranged on the flange plate 2, and the laser tracker 7 is arranged on one side of the to-be-processed optical element 5, for measuring the three-dimensional coordinates of the target ball 8 in a measurement coordinate system {M}, and fitting to obtain the center point, the radius, the side surface normal of the contact wheel 4 and the center point of the flange plate 2.

[0145] Further, the robot abrasive belt tool TCP calibration device based on pressure-laser cooperation can further comprise a control module, the control module is in communication connection with the robot device 1, the pressure collection module and the laser measurement module respectively, for receiving pressure data and laser measurement data, adjusting the shaft angle of the robot device 1 according to the pressure distribution deviation, and calculating the rotation matrix and the position quantity of the tool coordinate system {T} relative to the flange coordinate system based on the laser fitting result, to complete the TCP calibration.

[0146] The robot device 1 as an execution body, the rigid connection of the flange plate 2 and the abrasive belt tool module 3 provides a stable basis for the posture adjustment and pose transmission of the abrasive belt tool module 3, and ensures that the contact state of the contact wheel 4 and the optical element 5 to be processed is controllable. The pressure distribution collector 6 directly adheres to the surface of the optical element 5 to be processed, can obtain the pressure matrix data when the contact wheel 4 contacts in real time, and automatically calculates the key parameters such as the center of gravity and the second moment, provides quantitative pressure feedback basis for posture calibration, and avoids manual calculation error. The optical element 5 to be processed can be placed on the marble experimental platform 10, which can take advantage of the high flatness and high stability of the marble experimental platform 10 to ensure that the surface of the optical element 5 to be processed remains horizontal and fixed after being placed, avoid the inclination of the element caused by the unevenness or vibration of the platform, and then interfere with the contact state of the contact wheel 4 and the pressure distribution collector 6. The laser measurement module can accurately capture the actual geometric parameters of the flange plate 2 and the contact wheel 4 through the multi-position measurement and fitting function of the target ball 8, provide high-precision spatial data support for the establishment of the measurement coordinate system {M} and the positioning of the center point of the abrasive belt tool module 3, and eliminate the deviation between the theoretical parameters and the actual structure. The deep cooperation of "pressure feedback calibration posture" and "laser positioning quantitative pose" is realized, the functions of each component and the steps of the calibration method are one-to-one corresponding, which not only ensures the automation and accuracy of the calibration process, but also can adapt to different specifications of the abrasive belt tool module 3 and the optical element 5 to be processed, solves the problems of traditional calibration devices relying on manual operation, low precision and poor adaptability, and provides hardware support for realizing high-precision calibration of the TCP of the robot abrasive belt tool.

[0147] In some embodiments, an adapter plate 9 is arranged on the abrasive belt tool module 3, and the flange plate 2 is connected with the abrasive belt tool module 3 through the adapter plate 9.

[0148] The adapter plate 9 connects the flange 2 to the abrasive belt tool module 3. This design allows for compatibility with different specifications of the abrasive belt tool module 3. When changing the diameter of the contact wheel 4 or the type of abrasive belt in the abrasive belt tool module 3, it is not necessary to replace the flange 2; only the adapter plate 9 with the corresponding interface needs to be replaced, significantly improving the device's compatibility with different abrasive belt tools. Furthermore, the adapter plate 9 must be concentrically positioned with the flange 2 to ensure that their central axes are completely aligned, preventing misalignment after installation of the abrasive belt tool module 3. If the adapter plate 9 and the flange 2 are not concentric, the center of the abrasive belt tool module 3 (especially the contact wheel 4) will deviate from the center of the flange 2, directly causing the contact wheel 4 to tilt when contacting the optical element 5 to be processed. This will interfere with the accuracy of subsequent pressure distribution data acquisition and the precision of TCP position and attitude calibration. Meanwhile, the concentric setting ensures that the motion trajectory of the belt sander module 3 always revolves around the center reference of the flange 2 when the axis angle of the robot device 1 is adjusted, avoiding additional centrifugal force or vibration caused by eccentricity, ensuring the stability of the belt sander module 3 during the calibration process, providing a stable mechanical foundation for pressure calibration, laser measurement and other steps, and ultimately ensuring the consistency between the TCP calibration results and the actual working state of the belt sander module 3.

[0149] In addition, the adapter plate 9 can eliminate the error of the mounting surface of the sanding belt tool module 3 through precision machining. At the same time, its rigid structure can reduce the gap between the sanding belt tool module 3 and the flange 2, avoid tool posture deviation caused by loose connection, and ensure the coaxiality and perpendicularity of the sanding belt tool module 3 and the end of the robot device 1, providing a stable mechanical connection basis for the posture accuracy of subsequent TCP calibration.

[0150] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0151] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A TCP calibration method for robotic belt sanders based on pressure-laser coordination, characterized in that, Includes the following steps: S1. Input the theoretical parameters of the robot's end contact wheel relative to the center point of the flange, and adjust the device to the theoretical zero position posture; A target ball is placed on the cylindrical surface of the flange side. The driving device moves along the X, Y, and Z axes of its base coordinate system. The target ball coordinates of the laser tracker are recorded. The measurement coordinate system is fitted and made consistent with the coordinate axes of the device's base coordinate system. S2. Place the pressure distribution acquisition device on the upper surface of the optical element to be processed, maintain the zero position, drive the device to move above the pressure distribution acquisition device and make contact, save the pressure matrix data and record the current Z-axis position. S3. Rotate the six axes of the equipment, press down to the Z-axis position of step S2 and record the pressure data. Collect data within ±3° of the six axes, calculate the center of gravity coordinates and normalized deviation of the contact area, adjust according to the adjustment formula of the sixth axis, and lock the angle of the six axes when the normalized deviation is ≤0.

02. The formula for adjusting the sixth axis is: ； in, This represents the coordinates of the center of gravity of the pressure in the contact area between the contact wheel and the pressure distribution collector along the X-axis of the pressure distribution collector's coordinate system at different contact angles, where 'a' is the length of the major semi-axis of the pressure distribution ellipse. The theoretical center location of the contact area; S4. Rotate the first axis of the equipment, repeat the pressing and data acquisition in step S3, collect data within ±3° of the first axis, calculate the second moment and the asymmetry of the rotation direction, adjust according to the first axis adjustment formula, record the Euler angle when the asymmetry is <0.03, and calculate the rotation matrix of the flange coordinate system relative to the base coordinate system. The formula for adjusting the first axis is: ， in, This represents the adjustment amount of the first axis angle of the robot device; This represents the difference in the degree of dispersion of pressure distribution along the X-axis and Y-axis of the base coordinate system; The degree of deviation between the principal axis of the pressure distribution ellipse and the coordinate axes; S5. The target ball is adsorbed on the side surface of the contact wheel. The coordinates of at least four positions are measured. The normal of the side surface is fitted and normalized to obtain the X-axis direction vector of the tool coordinate system. The tool coordinate system is constructed by combining the Z-axis of the base coordinate system with the right-hand rule. The rotation matrix of the tool relative to the flange coordinate system is calculated and converted into a quaternion and input into the teach pendant to complete the attitude calibration. S6. Place a target ball on the outer surface of the contact wheel, measure the coordinates of at least four positions and fit the center point and radius to determine the lowest point of the contact wheel. Coordinates; the center point of the flange is calculated by measuring and fitting the target ball. Coordinates, calculation relatively Enter the position value and input the translation value into the teach pendant to complete the position calibration.

2. The TCP calibration method for robotic belt sanders based on pressure-laser collaboration according to claim 1, characterized in that: In step S3, the formula for calculating the centroid coordinates of the contact area is: ， ； in, In the coordinate system of the pressure distribution acquisition device The pressure value at that location, Represented as the first on the sensing surface of the pressure distribution collector i Line 1 j The coordinates of the column pixels along the X-axis in the coordinate system of the pressure distribution collector. Represented as the first on the sensing surface of the pressure distribution collector i Line 1 j The coordinates of the column pixels along the Y-axis in the coordinate system of the pressure distribution collector; The formula for calculating normalized bias is: ； in, This represents the coordinate value of the center of gravity of the pressure in the contact area between the contact wheel and the pressure distribution collector in the Y-axis direction of the pressure distribution collector's coordinate system under different contact angles.

3. The TCP calibration method for robotic belt sanders based on pressure-laser collaboration according to claim 1, characterized in that: In step S4, the formula for calculating the second moment is: ， ， ， in, This represents the degree of dispersion of pressure distribution along the X-axis of the base coordinate system. This represents the degree of dispersion of pressure distribution along the Y-axis of the base coordinate system. The degree of deviation between the principal axis of the pressure distribution ellipse and the coordinate axes; Rotational direction asymmetry The formula is: ， in, This represents the degree of inclination of the pressure distribution off the coordinate axes in the XY plane. It represents the overall dispersion of pressure distribution relative to the center of gravity.

4. The TCP calibration method for robotic belt sanders based on pressure-laser collaboration according to claim 1, characterized in that: In step S4, the formula for calculating the rotation matrix of the flange coordinate system relative to the base coordinate system is: ， ， ， ， in, Let Z, Y, and X represent the rotation angles of the current flange coordinate system around the base coordinate system, respectively. This is a rotation matrix about the X-axis. This is a rotation matrix about the Y-axis. This is the rotation matrix around the Z-axis.

5. The TCP calibration method for robotic belt sanders based on pressure-laser collaboration according to claim 1, characterized in that: In step S5, the formula for obtaining the normal to the surface containing the measurement point using least squares fitting is: in, The three-dimensional coordinates of a measurement point on the contact wheel side surface. , , This represents the normal vector component of the plane containing the contact wheel side surface obtained from the fitting; A three-dimensional coordinate variable representing any point on the normal; Contact wheel side surface normal vector The formula is: ； Will Normalized to unit vector The formula is: ， The formula for converting a rotation matrix to a quaternion is: ， in, , , , , , , , , These are the elements of the rotation matrix between the tool coordinate system and the flange coordinate system; The scalar part representing the quaternion is related to the rotation angle. , , The vector part representing the quaternion is related to the direction of the rotation axis.

6. The TCP calibration method for robotic belt sanders based on pressure-laser collaboration according to claim 1, characterized in that: In step S6, the lowest point of the contact wheel The coordinate formula is: in, The three-dimensional coordinates of the center point of the contact wheel in the measurement coordinate system; This represents the actual radius of the contact wheel; Represents the lowest point The z-coordinate; Flange center point The coordinate formula is: ， in, , The X and Z coordinates of the "center of the cylindrical surface on the side of the flange" obtained by the laser tracker fitting in the measurement coordinate system; The Y-axis coordinate in the measurement coordinate system when the target ball is placed at the center of the intersection of the flange and the adapter plate; This represents the standard radius of the target sphere used in the laser tracker. Lowest point of contact wheel relative flange center point The formula for position measurement is: 。 7. A TCP calibration device for robotic belt sanders based on pressure-laser coordination, characterized in that, The TCP calibration method for robotic belt sanders based on pressure-laser collaboration according to any one of claims 1 to 6 includes: A robotic device is provided with a flange, and a sanding belt tool module is connected to the flange. The sanding belt tool module includes a contact wheel, and the outer ring of the contact wheel abuts against the surface of the optical element to be processed. A pressure distribution collector is disposed on the surface of the optical element to be processed. It is used to collect pressure matrix data when the contact wheel contacts the pressure distribution collector, and to calculate the centroid coordinates, second moment and normalized deviation of the pressure distribution. The laser measurement module includes a laser tracker and a target ball. The target ball is set on the flange, and the laser tracker is set on one side of the optical element to be processed. It is used to measure the three-dimensional coordinates of the target ball in the measurement coordinate system and to fit the center point, radius, side surface normal, and center point of the flange of the contact wheel.

8. The pressure-laser synergistic robotic belt sander TCP calibration device according to claim 7, characterized in that: The belt abrasive tool module is equipped with an adapter plate, and the flange is connected to the belt abrasive tool module through the adapter plate.

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