Robot abrasive belt tool TCP calibration method and device based on pressure-laser cooperation

Abstract

The invention relates to the technical field of robot abrasive belt tool calibration, in particular to a robot abrasive belt tool TCP calibration method and device based on pressure-laser collaboration. A measurement coordinate system coaxial with a base coordinate system of robot equipment is established through a laser tracker, and pressure data of a contact wheel is collected by combining a pressure distribution collector; the zero posture of the tool is calibrated; and fitting geometric parameters of the contact wheel and the flange plate through laser, calculating a pose relation of a tool coordinate system relative to a flange coordinate system, and completing TCP calibration. The problems that the attitude calibration precision is low, the zero attitude cannot be calibrated and the result deviates from the real working state due to assembly and manufacturing errors are solved, and the method is suitable for high-precision machining scenes. The problems that due to tool assembly and manufacturing errors, the attitude calibration precision is low, the zero attitude cannot be calibrated, and then the TCP attitude calibration result deviates from the real working state are solved.

Description

Technical Field

[0001] This invention belongs to the field of robotic belt sander calibration technology, and particularly relates to a pressure-laser coordinated TCP calibration method and apparatus for robotic belt sanders. Background Technology

[0002] Robotic belt abrasion technology is a core processing technology in the field of precision manufacturing. This technology has significant advantages such as high removal rate, strong controllability of removal rate, and coverage of the entire "grinding-polishing" manufacturing process. The belt abrasion tool is rigidly connected to the end flange of the robot. The robot program controls the tool's posture, feed speed, and contact pressure to flexibly perform processing tasks on different materials (metals, composite materials, optical components, etc.).

[0003] In high-precision manufacturing fields such as optical processing, the accuracy of TCP calibration for belt abrasive equipment directly determines the processing precision. Currently, there are two main types of TCP calibration methods: the four-point calibration method and a single non-contact calibration scheme using a laser tracker. The four-point calibration method involves controlling a robot to move a needle-like object to a predetermined spatial position in different postures, making four contacts to calculate the TCP. However, this method relies heavily on manual operation and has relatively low calibration accuracy. The single non-contact calibration scheme using a laser tracker leverages the high-precision coordinate measurement capabilities of the laser tracker to fit the geometric features of the machining tool, indirectly calculating the TCP position and attitude parameters. However, this method ignores tool assembly and manufacturing errors, resulting in insufficient accuracy in attitude calibration. It cannot calibrate theoretical zero-position attitude deviations and relies too heavily on ideal tool conditions, causing the TCP attitude calibration results to deviate from the actual working state. Summary of the Invention

[0004] In view of this, the present invention aims to provide a pressure-laser coordinated robotic belt sander TCP calibration method and device to solve the problem that the attitude calibration accuracy is low due to tool assembly and manufacturing errors, and the inability to calibrate the zero position attitude, which in turn causes the TCP attitude calibration results to deviate from the actual working state.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows: The first aspect of this invention provides a TCP calibration method for robotic belt sanders based on pressure-laser coordination, comprising the following steps: S1. Input the theoretical parameters of the robot device's end contact wheel relative to the center point of the flange, and adjust the device to the theoretical zero position posture; place the target ball on the cylindrical surface of the flange side, drive the device to move along the X, Y, and Z axes of its base coordinate system, record the target ball coordinates of the laser tracker, fit the measurement coordinate system and make it 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. 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. 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.

[0006] Furthermore, 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 pressure distribution acquisition sensor on the sensing surface i Line number j The coordinates of the column pixels along the X-axis in the coordinate system of the pressure distribution collector. Represented as the first pressure distribution acquisition sensor on the sensing surface i Line number 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: ; 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. 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 Y-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. This is the theoretical center location of the contact area.

[0007] Furthermore, 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; 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. 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.

[0008] Furthermore, 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.

[0009] Furthermore, in step S5, the formula for obtaining the normal to the surface containing the measurement point using least-squares fitting is:

[0010] 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.

[0011] Furthermore, in step S6, the lowest point of the contact wheel The coordinate formula is:

[0012] 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 is the position of the target ball when it is placed at the center of the interface between 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: .

[0013] The second aspect of this invention provides a pressure-laser coordinated robotic belt sander TCP calibration device, and the pressure-laser coordinated robotic belt sander TCP calibration method according to any one of the first aspects above 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.

[0014] Furthermore, the belt sander module is equipped with an adapter plate, and the flange is connected to the belt sander module through the adapter plate.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: A measurement coordinate system coaxial with the robot's base coordinate system is established using a laser tracker to ensure consistency between the measurement reference and the robot's motion reference. Pressure data at different contact angles is then collected using a pressure distribution collector to calculate the center of gravity coordinates, second moment, and asymmetry, accurately calibrating the tool's theoretical zero-position attitude and avoiding deviations in the tool's lowest point due to machining and assembly errors. Finally, by fitting the contact wheel normal, center point, and flange center point using the laser tracker, the pose relationship between the tool coordinate system and the flange coordinate system is constructed, completing the dual calibration of TCP attitude and position. This solves the problem of low attitude calibration accuracy and inability to calibrate the zero-position attitude due to tool assembly and manufacturing errors, thus causing the TCP attitude calibration results to deviate from the actual working state. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A flowchart of a pressure-laser coordinated robotic belt abrasive tool TCP calibration method provided in an embodiment of the present invention; Figure 2 A schematic diagram of the overall structure of the pressure-laser synergy-based robotic belt sander TCP calibration device provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the belt sander module provided in an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: 1. Robot equipment; 2. Flange; 3. Belt sander module; 4. Contact wheel; 5. Optical element to be processed; 6. Pressure distribution acquisition device; 7. Laser tracker; 8. Target ball; 9. Adapter plate; 10. Marble experimental platform. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and do not constitute a limitation thereof. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the invention. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the invention are not shown or described in the specification. This is to avoid obscuring the core parts of the invention with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined to form various implementations. Furthermore, the order of the steps or actions in the method description can be changed or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, the first aspect of this embodiment provides a TCP calibration method for robotic belt sanders based on pressure-laser collaboration, including the following steps: S1. Based on the theoretical geometric parameters and attitude parameters of the working point of the end contact wheel 4 of robot device 1 relative to the center point of flange 2, input them into the teach pendant, and adjust the end attitude of robot device 1 to the theoretical zero position attitude; place the target ball 8 on the cylindrical surface of flange 2, and drive the robot device along its base coordinate system {B}. The axis is moved, and the coordinates of the target ball of the laser tracker at different positions on each coordinate axis are recorded simultaneously to fit the measurement coordinate system {M}. The axes are set so that the coordinate axes of the measurement coordinate system {M} are the same as the coordinate axes of the robot's base coordinate system {B}.

[0024] In this embodiment, the robot device 1 is a six-axis robot. First, based on the theoretical geometric parameters and attitude parameters of the working point of the end contact wheel 4 of the robot device 1 relative to the center point of the flange 2, these parameters are input into the teach pendant to clarify the initial pose reference of the contact wheel 4. At the same time, the attitude of the end of the robot device 1 is adjusted to the theoretical zero-position attitude to ensure that the contact wheel 4 conforms to the design processing state from the start of calibration, avoiding the reduction in efficiency due to excessive initial attitude deviation in subsequent calibration. Then, a target ball 8 is placed on the cylindrical surface of the flange 2, and the robot device 1 is driven to move along its base coordinate system {B}. The axis is moved, and the coordinates of the target ball 8 of the laser tracker 7 at different positions on each coordinate axis are recorded simultaneously, and the measurement coordinate system {M} is fitted. The axes are aligned so that the coordinate axes of the measurement coordinate system {M} are identical to those of the robot's base coordinate system {B}. This eliminates transformation errors between different coordinate systems, ensures the consistency and reliability of all calibration data, and avoids TCP calibration deviations caused by reference misalignment.

[0025] S2. Place the pressure distribution acquisition device 6 on the upper surface of the optical element 5 to be processed, ensuring that the coordinate system of the pressure distribution acquisition device 6 is the same as the measurement coordinate system {M}. While maintaining the theoretical zero-position attitude, drive the robot device 1 to move linearly above the pressure distribution acquisition device 6. Move the robot device 1 so that the contact wheel 4 contacts the pressure distribution acquisition device 6, save the pressure matrix data in the pressure distribution acquisition device 6, and record the current... Axis position.

[0026] By placing the pressure distribution acquisition device 6 on the surface of the optical element 5 to be processed, located above the marble experimental platform 10, and ensuring that the coordinate system of the pressure distribution acquisition device 6 is identical to the measurement coordinate system {M}, the spatial reference for pressure data acquisition is completely consistent with the laser measurement reference. This achieves coordinate system unification for "pressure feedback" and "laser positioning," providing a precise data association basis for subsequent calibration of the contact wheel 4's attitude based on pressure distribution characteristics. Simultaneously, while maintaining the theoretical zero-position attitude, the drive robot device 1 is linearly moved above the pressure distribution acquisition device 6, and then moved again to bring the contact wheel 4 into contact with the pressure distribution acquisition device 6. The pressure matrix data in the pressure distribution acquisition device 6 is saved, and the current Z-axis position is recorded. This process acquires the initial pressure distribution characteristics of the contact state between the contact wheel 4 and the optical element 5 to be processed, and simultaneously locks in the... The contact depth in the axial direction ensures 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, avoiding interference with the accuracy of attitude calibration due to pressure changes, thus laying a unified and controllable contact state foundation for the accurate calibration of the zero-position attitude.

[0027] S3. Slowly rotate the six axes of robot device 1, 0.5° each time, pressing robot device 1 down to the current position recorded in step S2. At the axis position, record the data from pressure distribution acquisition device 6. Repeat this step to collect pressure distribution data within a range of ±3° on six axes under the theoretical zero-position attitude, and calculate the centroid coordinates of the contact area under different contact angles. ,but: , ; in, For the pressure distribution acquisition device in the 6-coordinate system The pressure value at that location, Represented as the first pressure distribution acquisition sensor on the sensing surface i Line number j The coordinates of the column pixels along the X-axis in the coordinate system of the pressure distribution collector. Represented as the first pressure distribution acquisition sensor on the sensing surface i Line number jThe coordinates of the column pixels along the Y-axis in the coordinate system of the pressure distribution collector.

[0028] Next, calculate the normalized deviation between the pressure center of gravity and the center of the contact profile at different contact angles, then: ; Based on the deviation between the two, the sixth axis adjustment formula is defined as follows: ; 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. 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 Y-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. This is the theoretical center location of the contact area.

[0029] like Rotate the sixth axis clockwise, if Rotate the sixth axis counterclockwise; when the normalized deviation At this point, stop the horizontal calibration, lock and record the angle of the robot's sixth axis.

[0030] By controlling the six axes of robot device 1 to rotate in small steps within a range of ±3° and repeatedly pressing down to a fixed position. The axis position not only allows for comprehensive acquisition of pressure distribution data under different contact angles, but also ensures that the pressure state at each contact is consistent with the baseline in step S2, avoiding interference from pressure fluctuations on data validity; then, the discrete pressure matrix data is transformed into a quantified pressure center position using the centroid coordinates, combined with normalized deviation. The process eliminates the influence of differences in the size of the pressure distribution ellipse and accurately quantifies the degree of offset between the pressure center of gravity and the theoretical center. This process achieves a mathematical transformation from "pressure distribution characteristics" to "attitude deviation," making the previously difficult-to-intuitive horizontal attitude error calculable and adjustable.

[0031] At the same time, based on and The difference determines the rotation direction of the sixth axis, and the adjustment formula for the sixth axis is used. Provide specific adjustment criteria to ensure that every axis angle adjustment is supported by data, avoiding blind operation; ultimately, based on... As a calibration termination condition, it ensures that the symmetry of the pressure distribution in the horizontal direction meets the standard from a quantitative perspective, effectively corrects the horizontal attitude deviation caused by tool assembly deviation, locks the six-axis angle that conforms to the actual contact state, and provides a precise horizontal attitude reference for subsequent rotation direction calibration and TCP attitude calibration.

[0032] S4. Slowly rotate one axis of robot device 1, 0.5° each time, pressing robot device 1 down to the position recorded in step S2. At the axis position, record the data in pressure distribution acquisition device 6. Repeat this step to collect pressure distribution data within ±3° of the first axis in the theoretical zero-position attitude. Calculate the second moment to obtain the rotation angle of the pressure distribution ellipse relative to the coordinate axis. The formula for calculating the second moment is: , , , in, Represents the pressure distribution along the base coordinate system The degree of dispersion in the axial direction, Represents the pressure distribution along the base coordinate system The degree of dispersion in the axial direction, This represents the degree of deviation between the principal axis of the pressure distribution ellipse and the coordinate axes.

[0033] Then, define the first axis adjustment formula, then: , 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.

[0034] like Rotate the axis counterclockwise, if Rotate the axis clockwise.

[0035] Calculate rotational asymmetry ,but: , 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.

[0036] 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}. .

[0037] 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: , , , , but,

[0038] 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, To bypass Axis rotation matrix.

[0039] By controlling one axis of robot device 1 to rotate in small steps within a range of ±3° and maintain a fixed position. At the shaft-down pressure position, pressure distribution data under different rotational orientations can be comprehensively collected under stable contact pressure, avoiding interference from pressure changes on rotational orientation calibration. The pressure distribution data is then converted into quantified dispersion parameters using the second-order moment formula. This accurately captures the differences in tilt and dispersion of the pressure distribution ellipse. Among them, It directly reflects the degree of deviation between the principal axis of the ellipse and the coordinate axes. and The difference reflects the dispersion difference between the two axes, providing a mathematical quantitative basis for the attitude error in the rotation direction. The first-axis adjustment formula is derived based on the second-order moment. According to The clear positive and negative rotation directions provide precise data support for axis angle adjustments, avoiding blind operation. As a calibration termination condition, this quantitatively ensures that the pressure distribution in the rotational direction is symmetrical, effectively correcting rotational orientation deviations caused by tool manufacturing or assembly errors, and locking in a one-axis angle that conforms to the actual machining contact state. Finally, Euler angles are recorded. Calculate the rotation matrix of the flange coordinate system relative to the base coordinate system. The calibrated flange 2's posture is transformed into a mathematical model that the robot device 1 can recognize, providing a key flange posture reference for the subsequent construction of the pose relationship between the tool coordinate system {T} and the flange coordinate system and the completion of TCP posture calibration, ensuring the accurate quantification of posture calibration.

[0040] S5. Adsorb the target ball 8 onto the side surface of the contact wheel 4, slowly rotate the contact wheel 4 and measure the coordinates of the target ball 8 at at least four different positions, and use least squares fitting to obtain the normal to the surface where the measurement points are located. Then it can be expressed as: , in, , , This represents the three-dimensional coordinates of a measurement point on the four sides of the contact wheel. , , This represents the normal vector component of the plane containing the four side surfaces of the contact wheel obtained from the fitting; , , A three-dimensional coordinate variable representing any point on the normal; Determine the normal vectors of the four side surfaces of the contact wheel. ,but: ; Will Normalized to unit vector ,but: ; This unit vector For the tool coordinate system {T} The direction vector of the axis in the base coordinate system {B} ,Right now, ; The tool coordinate system {T} Axial direction vector With the base coordinate system {B} If the axes are aligned, then: According to the rules of the right-hand coordinate system, by Directional phasor of the axis and Direction vector of the axis The cross product yields the direction vector of the Y-axis. ,but:

[0041] in, These represent the coordinates of the base coordinate system {B}. , , The unit basis vectors of the axes.

[0042] Construct the rotation matrix of the tool coordinate system {T} relative to the base coordinate system {B} ,but:

[0043] Then by rotation matrix The chain relationship calculation tool calculates the rotation matrix of coordinate system {T} relative to the flange coordinate system. ,but:

[0044] Converting it to a quaternion for the robot device 1 teach pendant and inputting it into the robot device 1 teach pendant completes the TCP attitude calibration. The formula for converting the rotation matrix to a quaternion is then: , 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.

[0045] 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.

[0046] 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 Determine the lowest point of contact wheel 4 Given the coordinates, then:

[0047] in, The three-dimensional coordinates of the center point of contact wheel 4 in the measurement coordinate system {M}; This represents the actual radius of contact wheel 4; Represents the lowest point The z-coordinate.

[0048] Place and fix the target ball 8 on the cylindrical surface of the flange 2. Rotate the sixth axis at the end of the robot device 1 to measure the coordinates of the target ball 8 at different positions in the measurement coordinate system {M}. The number of measurement points should be no less than four. Use the ball fitting function of the laser tracker 7 to determine the coordinates of the center point of the circle where the target ball 8 is located. Place the target ball 8 near the center of the interface between the flange 2 and the adapter plate, and measure the coordinates of the target ball 8 at this point. Calculate the center point of flange 2 Coordinates, then: , in, , The center of the cylindrical surface on the side of flange 2, obtained by fitting with laser tracker 7, is located in the measurement coordinate system {M}. shaft and Axis coordinates; When the target ball 8 is placed at the center of the intersection of flange 2 and adapter plate, in the measurement coordinate system {M} coordinate; The standard radius of the target sphere 8 used in the laser tracker 7 represents the standard radius of the target sphere 8.

[0049] Then calculate the lowest point of contact wheel 4. Relative to the center point of flange 2 Position quantity ,but: , position quantity Input the translation value into the teach pendant of robot device 1 to complete the TCP position calibration.

[0050] By measuring the coordinates of the target ball 8 at multiple locations on the outer surface of the contact wheel 4 and fitting the ball, the actual center point and radius of the contact wheel 4 can be directly obtained (instead of relying on design values). This effectively eliminates the influence of manufacturing errors of the contact wheel 4 (such as diameter deviation) on the calculation of the lowest point, ensuring the core action point of TCP (the lowest point of the contact wheel 4). T The accuracy of the coordinates is ensured; however, by fitting the center of the cylindrical surface of the flange 2 side and measuring the center of the intersection with the target ball 8, and combining this with the radius correction of the target ball 8, the center point of the flange can be accurately located. P This solved the problem of datum offset caused by assembly deviation between the flange and the adapter plate, ensuring that the flange datum conforms to the actual structural condition. Further calculations were then performed. T relatively P Position quantity Ultimately, the position quantity Input the translation value of the teach pendant so that robot device 1 can accurately identify the position of TCP relative to flange 2, ensuring the positioning accuracy of robot device 1 on the action point of contact wheel 4 during subsequent processing, and meeting the requirement that the TCP position and the actual working state are completely matched in high-precision processing scenarios.

[0051] Through the above technical solution, a measurement coordinate system {M} coaxial with the base coordinate system {B} is established using a laser tracker 7, ensuring that the measurement reference is consistent with the motion reference of the robot device 1. Then, pressure data at different contact angles is collected using a pressure distribution collector 6 to calculate the center of gravity coordinates, second moment, and asymmetry, accurately calibrating the theoretical zero-position attitude of the tool and avoiding deviations in the tool's lowest point due to machining and assembly errors. Finally, by combining the laser tracker 7 with the fitting of the normal, center point, and center point of the contact wheel 4 and flange 2, the positional relationship between the tool coordinate system {T} and the flange coordinate system is constructed, completing the dual calibration of TCP attitude and position. This solves the problem of low attitude calibration accuracy and inability to calibrate the zero-position attitude due to tool assembly and manufacturing errors, thus causing the TCP attitude calibration results to deviate from the actual working state.

[0052] The second aspect of this invention provides a pressure-laser coordinated robotic belt sander TCP calibration device, according to any of the first aspects above, comprising a robotic device 1, a pressure distribution acquisition device 6, and a laser measurement module. The robotic device 1 is equipped with a flange 2, and a belt sander module 3 is connected to the flange 2. The belt sander module 3 includes a contact wheel 4, the outer ring of which abuts against the surface of the optical element 5 to be processed. The pressure distribution acquisition device 6 is disposed on the surface of the optical element 5 to be processed, and is used to acquire pressure matrix data when the contact wheel 4 contacts the pressure distribution acquisition device 6, and to calculate the centroid coordinates, second moment, and normalized deviation of the pressure distribution. The laser measurement module includes a laser tracker 7 and a target ball 8. The target ball 8 is disposed on the flange 2, and the laser tracker 7 is disposed on one side of the optical element 5 to be processed, and is used to measure the three-dimensional coordinates of the target ball 8 in the measurement coordinate system {M}, and to fit the center point, radius, side surface normal of the contact wheel 4, and the center point of the flange 2.

[0053] Furthermore, the pressure-laser collaborative robotic belt sander TCP calibration device may also include a control module. The control module is communicatively connected to the robotic device 1, the pressure acquisition module, and the laser measurement module, respectively. It is used to receive pressure data and laser measurement data, adjust the axis angle of the robotic device 1 according to the pressure distribution deviation, and calculate the rotation matrix and position of the tool coordinate system {T} relative to the flange coordinate system based on the laser fitting results to complete the TCP calibration.

[0054] Robotic device 1, acting as the execution entity, has a rigid connection between its flange 2 and the abrasive belt tool module 3. This provides a stable foundation for the posture adjustment and position transmission of the abrasive belt tool module 3, ensuring controllable contact between the contact wheel 4 and the optical element 5 to be processed. The pressure distribution acquisition device 6 directly contacts the surface of the optical element 5, acquiring real-time pressure matrix data when the contact wheel 4 contacts it. It automatically calculates key parameters such as the center of gravity and second moment, providing quantitative pressure feedback for posture calibration and avoiding errors from manual calculations. The optical element 5 can be placed on the marble experimental platform 10. The high flatness and stability of the marble experimental platform 10 ensure that the surface of the optical element 5 remains horizontal and its position is fixed after placement, preventing tilting of the element due to unevenness or vibration of the platform itself, which could interfere with the contact state between the contact wheel 4 and the pressure distribution acquisition device 6. The laser measurement module, through multi-position measurement and fitting functions of the target ball 8, accurately captures the actual geometric parameters of the flange 2 and the contact wheel 4, providing high-precision spatial data support for establishing the measurement coordinate system {M} and locating the center point of the abrasive belt tool module 3, eliminating deviations between theoretical parameters and actual structures. It achieves deep synergy between "pressure feedback calibration posture" and "laser positioning quantification posture". The functions of each component correspond one-to-one with the steps of the calibration method, which not only ensures the automation and accuracy of the calibration process, but also adapts to different specifications of abrasive belt tool modules 3 and optical components to be processed 5. It solves the problems of traditional calibration devices relying on manual labor, low accuracy and poor adaptability, and provides hardware guarantee for realizing high-precision calibration of robotic abrasive belt tools TCP.

[0055] In some embodiments, the belt sander module 3 is provided with an adapter plate 9, and the flange 2 is connected to the belt sander module 3 through the adapter plate 9.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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 robot abrasive belt tool TCP calibration method based on pressure-laser synergy, characterized in that, The method comprises the following steps: S1, input the theoretical parameters of the contact wheel of the robot device relative to the center point of the flange plate, and adjust the device to the theoretical zero attitude; The target ball is placed on the cylindrical surface of the flange plate, the device is driven to move along the X, Y and Z axes of its base coordinate system, the coordinates of the target ball of the laser tracker are recorded, a measurement coordinate system is fitted and made consistent with the coordinate axes of the base coordinate system of the device; S2, place the pressure distribution collector on the upper surface of the optical element to be processed, maintain 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; S3, rotate the six-axis of the 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 and normalized deviation of the contact area, adjust according to the sixth axis adjustment formula, and lock the six-axis angle when the normalized deviation is less than or equal to 0.02; S4, rotate the first axis of the device, repeat the pressing down and data collection of step S3, collect data within the range of ±3° of the first axis, calculate the second moment and rotational direction asymmetry, adjust according to the first axis adjustment formula, and record the Euler angle when the asymmetry is less than 0.03, and calculate the rotation matrix of the flange coordinate system relative to the base coordinate system; S5, the target ball is adsorbed on the side surface of the contact wheel, at least four position coordinates are measured, the side surface normal is fitted and normalized to obtain the X-axis direction vector of the tool coordinate system, the tool coordinate system is constructed in combination with the Z-axis of the base coordinate system and the right-hand rule, the rotation matrix of the tool coordinate system relative to the flange coordinate system is calculated and converted into a quaternion to input the teach pendant, and the attitude calibration is completed; S6, place a 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 of the contact wheel coordinates; flange center point is calculated by target ball measurement and fitting coordinates, calculation relative position quantity and input the teaching device translation value, complete position calibration.

2. The pressure-laser synergy based robot abrasive belt tool TCP calibration method of claim 1, wherein: In step S3, the center of gravity coordinates of the contact area are calculated according to the following formula: ， ； in, In the coordinate system of the pressure distribution acquisition device The pressure value at that location, Represented as the first pressure distribution acquisition sensor on the sensing surface 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 pressure distribution acquisition sensor on the sensing surface i Line 1 j The coordinates of the column pixels along the Y-axis in the coordinate system of the pressure distribution collector; The normalized deviation is calculated according to the following formula: ； The sixth axis adjustment formula is: ； wherein, represents 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 at different contact angles, represents 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 at 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.

3. The pressure-laser synergy based robot abrasive belt tool TCP calibration method of claim 1, wherein: In step S4, the second moment is calculated according to the following formula: ， ， ， wherein, represents a degree of dispersion of the pressure distribution along the X-axis direction of the base coordinate system, represents a degree of dispersion of the pressure distribution along the Y-axis direction of the base coordinate system, represents a degree of deviation of the major axis of the pressure distribution ellipse from the coordinate axis; The first axis adjustment formula is: ， wherein, represents a first-axis angle adjustment amount of the robot device; represents a difference in dispersion degree of the pressure distribution in the X-axis direction and the Y-axis direction of the base coordinate system; Rotational direction asymmetry The formula is: ， wherein, represents the degree of tilt of the pressure distribution from the coordinate axes in the X-Y plane, represents the total degree of dispersion of the pressure distribution from the center of gravity.

4. The pressure-laser synergy based robot abrasive belt tool TCP calibration method of claim 1, wherein: In step S4, the rotation matrix of the flange coordinate system relative to the base coordinate system is calculated according to the following formula: ， ， ， ， wherein, respectively represent the rotation angles of the current flange coordinate system around the Z-axis, the Y-axis and the X-axis of the base coordinate system, respectively, and is the rotation matrix around the X-axis, is the rotation matrix around the Y-axis, is the rotation matrix around the Z-axis.

5. The pressure-laser synergy based robot abrasive belt tool TCP calibration method of claim 1, wherein: In step S5, the formula for fitting the normal of the plane on which the measured points are located by using the least squares is: wherein represents the three-dimensional coordinates of a measuring point on the lateral surface of the contact wheel, , , represents the normal vector component of the plane in which the fitted lateral surface of the contact wheel lies; represents the three-dimensional coordinates of a point on the normal line; Contact wheel side surface normal vector The formula is: ； The normalized to unit vectors The formula is: ， The rotation matrix to quaternion formula is: ， wherein , , , , , , , , is an element 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.

6. The pressure-laser synergy based robot abrasive belt tool TCP calibration method of claim 1, wherein: In step S6, the contact wheel lowest point The coordinate formula is: wherein represents the three-dimensional coordinates of the center point of the contact wheel in the measuring coordinate system; represents the actual radius of the contact wheel; represents the z-coordinate of the lowest point of the contact wheel. flange center point The coordinate formula of the flange center point 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. Contact wheel lowest point Relative flange center point The position amount formula is: 。 7. A pressure-laser synergy based robot abrasive belt tool TCP calibration device, characterized in that, The robot abrasive belt tool TCP calibration method based on pressure-laser cooperation according to any one of claims 1 to 6 comprises: A robot device, a flange plate is arranged on the robot device, an abrasive belt tool module is connected to the flange plate, the abrasive belt tool module comprises a contact wheel, and the outer ring of the contact wheel is in abutment with the surface of an optical element to be processed; A pressure distribution collector is arranged on the surface of the optical element to be processed, and is used to collect pressure matrix data when the contact wheel contacts the pressure distribution collector, and to calculate the center of gravity coordinates, the second moment and the normalized deviation of the pressure distribution; A laser measurement module comprises a laser tracker and a target ball, the target ball is arranged on the flange plate, and the laser tracker is arranged on one side of the optical element to be processed, and is used to measure the three-dimensional coordinates of the target ball in a measurement coordinate system, and to fit the center point, the radius, the side surface normal of the contact wheel and the center point of the flange plate.

8. The pressure-laser synergy based robot abrasive belt tool TCP calibration apparatus of claim 7, wherein: An adapter plate is arranged on the abrasive belt tool module, and the flange plate is connected to the abrasive belt tool module through the adapter plate.

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