Parameter calibration method of five-axis motion platform, terminal device and storage medium

Abstract

The application discloses a kind of parameter calibration method of five-axis motion platform, terminal equipment and storage medium, and is related to the technical field of automation equipment.The method comprises: when first rotating shaft and second rotating shaft are each preset rotation angle combination, by monocular camera and laser ranging unit, the corresponding each equipment space coordinates of monocular camera alignment calibration point are obtained;The transformation relationship between the equipment space coordinate system of five-axis motion platform and workpiece coordinate system is obtained, wherein the transformation relationship contains error term;According to each equipment space coordinate, the preset workpiece coordinate of calibration point and transformation relationship, the error parameter of error term is obtained, to realize the parameter calibration of five-axis motion platform.The application improves the calibration efficiency of error parameter of five-axis motion platform.

Description

Technical Field

[0001] This invention relates to the field of automation equipment technology, and in particular to a parameter calibration method, terminal equipment, and computer storage medium for a five-axis motion platform. Background Technology

[0002] With the rapid development of the smart hardware industry, people have increasingly higher requirements for product user experience, comfort, and appearance. Product forms and appearances are becoming more complex, placing higher demands on the manufacturing industry and leading to a surge in demand for five-axis machining centers. Currently, the machine tool industry uses methods such as ballbars and laser interferometers to measure machine tool mechanical parameters before calibration. While these methods offer high accuracy, they suffer from high calibration costs and low efficiency. Summary of the Invention

[0003] The main objective of this invention is to provide a parameter calibration method, apparatus, terminal equipment, and computer storage medium for a five-axis motion platform, aiming to solve the technical problems of high calibration cost and low efficiency of five-axis motion platforms.

[0004] To achieve the above objectives, the present invention provides a parameter calibration method for a five-axis motion platform. The method is applied to a five-axis motion platform, wherein a monocular camera and a laser ranging unit are mounted on the Z-axis of the platform, and the axial directions of the monocular camera and the laser ranging unit are parallel to the axial direction of the Z-axis; a calibration plate is placed on the first rotation axis of the five-axis motion platform, and calibration points are provided on the calibration plate, wherein the axis of the first rotation axis is parallel to the Z-axis.

[0005] The method includes:

[0006] When the first rotation axis and the second rotation axis are respectively each preset rotation angle combination, the spatial coordinates of each device when the monocular camera is aligned with the calibration point are obtained through the monocular camera and the laser ranging unit;

[0007] Obtain the transformation relationship between the equipment space coordinate system and the workpiece coordinate system of the five-axis motion platform, where the transformation relationship includes an error term;

[0008] Based on the spatial coordinates of each device, the preset workpiece coordinates of the calibration points, and the transformation relationship, the error parameters of the error terms are obtained to achieve parameter calibration of the five-axis motion platform.

[0009] Optionally, before the step of obtaining the corresponding spatial coordinates of each device when the monocular camera aligns with the calibration point using the monocular camera and the laser ranging unit, when the first rotation axis and the second rotation axis are respectively each preset rotation angle combination, the following steps are included:

[0010] Obtain the radial and axial offset values ​​of the laser ranging unit and the monocular camera.

[0011] Optionally, when the first rotation axis and the second rotation axis are respectively various preset rotation angle combinations, the step of obtaining the spatial coordinates of each device corresponding to the alignment calibration point of the monocular camera through the monocular camera and the laser ranging unit includes:

[0012] When the first rotation axis and the second rotation axis are any combination of rotation angles, control the X-axis, Y-axis and Z-axis of the five-axis motion platform to move until the optical center of the monocular camera is aligned with the calibration point to obtain the first spatial coordinates;

[0013] The first alignment coordinates are obtained based on the first spatial coordinates, radial offset value, and axial offset value;

[0014] The X, Y, and Z axes of the five-axis motion platform are controlled to move to the first alignment coordinates so that the spot of the laser ranging unit is aligned with the calibration point. The Z axis is then controlled to move until the reading of the laser ranging unit is the value corresponding to the preset laser height, thus obtaining the second alignment coordinates.

[0015] Based on the second alignment coordinates, radial offset value, and axial offset value, the third alignment coordinates are obtained, and the third alignment coordinates are used as the device space coordinates corresponding to the rotation angle combination.

[0016] Optionally, after the step of obtaining the third alignment coordinates based on the second alignment coordinates, the radial offset value, and the axial offset value, the method includes:

[0017] Control the X, Y, and Z axes of the five-axis motion platform to move to the third alignment coordinate, and then control the X and Y axes of the five-axis motion platform to move so that the optical center of the monocular camera is aligned with the calibration point, thereby obtaining the device space coordinates corresponding to the rotation angle combination.

[0018] Optionally, the step of obtaining the transformation relationship between the device space coordinate system and the workpiece coordinate system of the five-axis motion platform, wherein the transformation relationship includes error terms, includes:

[0019] Obtain the workpiece transfer chain error matrix and the tool transfer chain error matrix of the five-axis motion platform;

[0020] Based on the workpiece transfer chain error matrix and the tool transfer chain error matrix, the position coordinate expression and pose vector expression in the workpiece coordinate system are obtained. The position coordinate expression and pose vector expression are used as the transformation relationship between the equipment space coordinate system and the workpiece coordinate system.

[0021] Optionally, the step of obtaining the error parameters of the error term based on the spatial coordinates of each device, the preset workpiece coordinates of the calibration points, and the transformation relationship includes:

[0022] Substituting the spatial coordinates of each device and the preset workpiece coordinates into the position coordinate expression and the pose vector expression, we obtain the corresponding nonlinear equation set.

[0023] The nonlinear equation system is solved using Newton's iteration method to obtain the error parameters of the error term;

[0024] The existing error parameters of the five-axis motion platform are updated based on the error parameters to achieve parameter calibration of the five-axis motion platform.

[0025] Optionally, the step of obtaining the radial offset values ​​of the laser ranging unit and the monocular camera includes:

[0026] When the rotation angles of the first and second rotation axes of the five-axis motion platform are both zero degrees, the X and Y axes of the five-axis motion platform are controlled to move until the spot of the laser ranging unit falls into the preset small hole of the same size as the spot on the platform of the five-axis motion platform, and the first laser horizontal and vertical coordinates are obtained.

[0027] Control the movement of the five-axis motion platform along the X, Y, and Z axes until the optical center of the monocular camera is aligned with the preset small hole, thus obtaining the horizontal and vertical coordinates of the first camera;

[0028] Based on the first laser's horizontal and vertical coordinates and the first camera's horizontal and vertical coordinates, the radial offset values ​​of the laser ranging unit and the monocular camera are obtained.

[0029] Optionally, the step of obtaining the radial offset values ​​of the laser ranging unit and the monocular camera further includes:

[0030] The X, Y, and Z axes of the five-axis motion platform are controlled to move until the laser rangefinder unit's spot falls onto the surface of a preset ball on the platform and maintains a preset fixed distance from the surface, thereby obtaining multiple spherical coordinates of the preset ball.

[0031] By fitting a sphere to multiple spherical coordinates, the coordinates of the center of the preset sphere are obtained.

[0032] Control the X and Y axes of the five-axis motion platform to move until the optical center of the monocular camera aligns with the center of the circle on the preset ball image, and obtain the center coordinates;

[0033] Based on the coordinates of the sphere's center and the circle's center, the radial offset values ​​of the laser ranging unit and the monocular camera are obtained.

[0034] Optionally, the step of obtaining the radial offset values ​​of the laser ranging unit and the monocular camera further includes:

[0035] The X-axis and Y-axis of the five-axis motion platform are controlled to move, so that the laser ranging unit scans the first straight line and the second straight line respectively, and obtains multiple first straight line coordinates and second straight line coordinates of the first straight line and the second straight line, wherein the first straight line and the second straight line have an intersection point;

[0036] The equation of the first line is obtained by fitting a line to multiple coordinates of the first line; the equation of the second line is obtained by fitting a line to multiple coordinates of the second line.

[0037] Based on the equations of the first and second lines, the coordinates of the first intersection point are obtained.

[0038] Control the X-axis and Y-axis of the five-axis motion platform to move until the optical center of the monocular camera is aligned with the intersection point, and obtain the second intersection point coordinates;

[0039] Based on the coordinates of the first and second intersection points, the radial offset values ​​of the laser ranging unit and the monocular camera are obtained.

[0040] Optionally, the step of obtaining the axial offset values ​​of the laser ranging unit and the monocular camera includes:

[0041] Control the movement of the five-axis motion platform along the X, Y, and Z axes until the optical center of the monocular camera aligns with the calibration point on the calibration plate, thus obtaining the camera's vertical coordinates;

[0042] Based on the radial offset value, the X and Y axes of the five-axis motion platform are controlled to move so that the spot of the laser ranging unit is aligned with the calibration point. The Z axis of the five-axis motion platform is also controlled to move until the reading of the laser ranging unit is the value corresponding to the preset laser height, thus obtaining the laser vertical coordinate.

[0043] Based on the camera's vertical coordinates and the laser's vertical coordinates, the axial offset values ​​of the laser ranging unit and the monocular camera are obtained.

[0044] In addition, to achieve the above objectives, the present invention also provides a terminal device, which includes: a memory, a processor, and a parameter calibration program for a five-axis motion platform stored in the memory and executable on the processor. When the parameter calibration program for the five-axis motion platform is executed by the processor, it implements the steps of the parameter calibration method for the five-axis motion platform as described above.

[0045] In addition, to achieve the above objectives, the present invention also provides a computer storage medium storing a parameter calibration program for a five-axis motion platform, wherein when the parameter calibration program for the five-axis motion platform is executed by a processor, the parameter calibration program for the five-axis motion platform implements the steps of the parameter calibration method for the five-axis motion platform as described above.

[0046] This invention provides a parameter calibration method, terminal device, and computer storage medium for a five-axis motion platform. The method applies to a five-axis motion platform, where a monocular camera and a laser ranging unit are mounted on the Z-axis, with the axes of the monocular camera and laser ranging unit parallel to the Z-axis. A calibration plate with calibration points is placed on the first rotation axis of the five-axis motion platform, and the axis of the first rotation axis is parallel to the Z-axis. With the first and second rotation axes representing preset rotation angle combinations, the spatial coordinates of each device when the monocular camera aligns with the calibration points are obtained using the monocular camera and laser ranging unit. The transformation relationship between the device spatial coordinate system and the workpiece coordinate system of the five-axis motion platform is acquired, including an error term. Based on the device spatial coordinates, the preset workpiece coordinates of the calibration points, and the transformation relationship, error parameters of the error term are obtained to achieve parameter calibration of the five-axis motion platform.

[0047] In one embodiment of the present invention, a monocular camera and a laser ranging unit are mounted on the Z-axis of a five-axis motion platform, wherein the axes of the monocular camera and the laser ranging unit are parallel to the Z-axis; and a calibration plate with calibration points is placed on the first rotation axis of the five-axis motion platform, wherein the axis of the first rotation axis is parallel to the Z-axis. Then, when the first and second rotation axes are respectively given preset rotation angle combinations, the calibration plate adopts different postures. The accurate radial position when aligned with the calibration points is determined by the monocular camera, and the accurate axial position when aligned with the calibration points is determined by the laser ranging unit, thus obtaining the corresponding spatial coordinates of each device when aligned with the calibration points. Then, the transformation relationship between the device spatial coordinate system and the workpiece coordinate system of the five-axis motion platform is obtained, and the transformation relationship includes an error term. Finally, based on the spatial coordinates of each device, the preset workpiece coordinates of the calibration points, and the transformation relationship, the error parameters of the error term are obtained to achieve parameter calibration of the five-axis motion platform.

[0048] Thus, this invention combines a laser ranging unit and a monocular camera to calculate and calibrate the error parameters of a five-axis motion platform, effectively reducing calibration costs and improving calibration efficiency. Furthermore, the calibration method of this invention is applicable to most five-axis devices, exhibiting strong versatility and facilitating the rapid popularization and application of five-axis equipment. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the device structure of the hardware operating environment involved in the embodiments of the present invention;

[0050] Figure 2 This is a flowchart illustrating an embodiment of the parameter calibration method for the five-axis motion platform of the present invention.

[0051] Figure 3This is a schematic diagram illustrating an application scenario of an embodiment of the parameter calibration method for the five-axis motion platform of the present invention;

[0052] Figure 4 This is a schematic diagram of a scene for obtaining the radial offset values ​​of a laser ranging unit and a monocular camera, as per the present invention.

[0053] Figure 5 This is a schematic diagram of another scenario for obtaining the radial offset values ​​of the laser ranging unit and the monocular camera involved in this invention;

[0054] Figure 6 This is a schematic diagram of another scenario for obtaining the radial offset values ​​of the laser ranging unit and the monocular camera involved in this invention;

[0055] Figure 7 This is a schematic diagram of a scene in which the optical center of the monocular camera involved in this invention is aligned with the calibration point.

[0056] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0057] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0058] Reference Figure 1 , Figure 1 This is a schematic diagram of the device structure of the hardware operating environment involved in the embodiments of the present invention.

[0059] The terminal device in this invention embodiment can be an MCU (Microcontroller Unit, also known as a Single Chip Microcomputer), a smartphone, a PC (Personal Computer), a tablet computer, a portable computer, or a server, etc.

[0060] like Figure 1As shown, the terminal device may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. The communication bus 1002 is used to enable communication between these components. The user interface 1003 may include a display screen and an input unit such as a keyboard; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface). The memory 1005 may be high-speed random access memory (RAM) or stable non-volatile memory (NVM), such as a disk drive. The memory 1005 may also optionally be a storage device independent of the aforementioned processor 1001.

[0061] Those skilled in the art will understand that Figure 1 The device structure shown does not constitute a limitation on the terminal device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0062] like Figure 1 As shown, the memory 1005, which serves as a computer storage medium, may include an operating system, a network communication module, a user interface module, and a parameter calibration program for a five-axis motion platform.

[0063] exist Figure 1 In the terminal shown, network interface 1004 is mainly used to connect to the backend server and communicate data with it; user interface 1003 is mainly used to connect to the client and communicate data with it; and processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in memory 1005 and execute the following steps:

[0064] When the first rotation axis and the second rotation axis are respectively each preset rotation angle combination, the spatial coordinates of each device when the monocular camera is aligned with the calibration point are obtained through the monocular camera and the laser ranging unit;

[0065] Obtain the transformation relationship between the equipment space coordinate system and the workpiece coordinate system of the five-axis motion platform, where the transformation relationship includes an error term;

[0066] Based on the spatial coordinates of each device, the preset workpiece coordinates of the calibration points, and the transformation relationship, the error parameters of the error terms are obtained to achieve parameter calibration of the five-axis motion platform.

[0067] Furthermore, the processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in the memory 1005, and also perform the following steps:

[0068] Obtain the radial and axial offset values ​​of the laser ranging unit and the monocular camera.

[0069] Furthermore, the processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in the memory 1005, and also perform the following steps:

[0070] When the first rotation axis and the second rotation axis are any combination of rotation angles, control the X-axis, Y-axis and Z-axis of the five-axis motion platform to move until the optical center of the monocular camera is aligned with the calibration point to obtain the first spatial coordinates;

[0071] The first alignment coordinates are obtained based on the first spatial coordinates, radial offset value, and axial offset value;

[0072] The X, Y, and Z axes of the five-axis motion platform are controlled to move to the first alignment coordinates so that the spot of the laser ranging unit is aligned with the calibration point. The Z axis is then controlled to move until the reading of the laser ranging unit is the value corresponding to the preset laser height, thus obtaining the second alignment coordinates.

[0073] Based on the second alignment coordinates, radial offset value, and axial offset value, the third alignment coordinates are obtained, and the third alignment coordinates are used as the device space coordinates corresponding to the rotation angle combination.

[0074] Furthermore, the processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in the memory 1005, and also perform the following steps:

[0075] Control the X, Y, and Z axes of the five-axis motion platform to move to the third alignment coordinate, and then control the X and Y axes of the five-axis motion platform to move so that the optical center of the monocular camera is aligned with the calibration point, thereby obtaining the device space coordinates corresponding to the rotation angle combination.

[0076] Furthermore, the processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in the memory 1005, and also perform the following steps:

[0077] Obtain the workpiece transfer chain error matrix and the tool transfer chain error matrix of the five-axis motion platform;

[0078] Based on the workpiece transfer chain error matrix and the tool transfer chain error matrix, the position coordinate expression and pose vector expression in the workpiece coordinate system are obtained. The position coordinate expression and pose vector expression are used as the transformation relationship between the equipment space coordinate system and the workpiece coordinate system.

[0079] Furthermore, the processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in the memory 1005, and also perform the following steps:

[0080] Substituting the spatial coordinates of each device and the preset workpiece coordinates into the position coordinate expression and the pose vector expression, we obtain the corresponding nonlinear equation set.

[0081] The nonlinear equation system is solved using Newton's iteration method to obtain the error parameters of the error term;

[0082] The existing error parameters of the five-axis motion platform are updated based on the error parameters to achieve parameter calibration of the five-axis motion platform.

[0083] Furthermore, the processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in the memory 1005, and also perform the following steps:

[0084] When the rotation angles of the first and second rotation axes of the five-axis motion platform are both zero degrees, the X and Y axes of the five-axis motion platform are controlled to move until the spot of the laser ranging unit falls into the preset small hole of the same size as the spot on the platform of the five-axis motion platform, and the first laser horizontal and vertical coordinates are obtained.

[0085] Control the movement of the five-axis motion platform along the X, Y, and Z axes until the optical center of the monocular camera is aligned with the preset small hole, thus obtaining the horizontal and vertical coordinates of the first camera;

[0086] Based on the first laser's horizontal and vertical coordinates and the first camera's horizontal and vertical coordinates, the radial offset values ​​of the laser ranging unit and the monocular camera are obtained.

[0087] Furthermore, the processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in the memory 1005, and also perform the following steps:

[0088] The X, Y, and Z axes of the five-axis motion platform are controlled to move until the laser rangefinder unit's spot falls onto the surface of a preset ball on the platform and maintains a preset fixed distance from the surface, thereby obtaining multiple spherical coordinates of the preset ball.

[0089] By fitting a sphere to multiple spherical coordinates, the coordinates of the center of the preset sphere are obtained.

[0090] Control the X and Y axes of the five-axis motion platform to move until the optical center of the monocular camera aligns with the center of the circle on the preset ball image, and obtain the center coordinates;

[0091] Based on the coordinates of the sphere's center and the circle's center, the radial offset values ​​of the laser ranging unit and the monocular camera are obtained.

[0092] Furthermore, the processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in the memory 1005, and also perform the following steps:

[0093] The X-axis and Y-axis of the five-axis motion platform are controlled to move, so that the laser ranging unit scans the first straight line and the second straight line respectively, and obtains multiple first straight line coordinates and second straight line coordinates of the first straight line and the second straight line, wherein the first straight line and the second straight line have an intersection point;

[0094] The equation of the first line is obtained by fitting a line to multiple coordinates of the first line; the equation of the second line is obtained by fitting a line to multiple coordinates of the second line.

[0095] Based on the equations of the first and second lines, the coordinates of the first intersection point are obtained.

[0096] Control the X-axis and Y-axis of the five-axis motion platform to move until the optical center of the monocular camera is aligned with the intersection point, and obtain the second intersection point coordinates;

[0097] Based on the coordinates of the first and second intersection points, the radial offset values ​​of the laser ranging unit and the monocular camera are obtained.

[0098] Furthermore, the processor 1001 can be used to call the parameter calibration program of the five-axis motion platform stored in the memory 1005, and also perform the following steps:

[0099] Control the movement of the five-axis motion platform along the X, Y, and Z axes until the optical center of the monocular camera aligns with the calibration point on the calibration plate, thus obtaining the camera's vertical coordinates;

[0100] Based on the radial offset value, the X and Y axes of the five-axis motion platform are controlled to move so that the spot of the laser ranging unit is aligned with the calibration point. The Z axis of the five-axis motion platform is also controlled to move until the reading of the laser ranging unit is the value corresponding to the preset laser height, thus obtaining the laser vertical coordinate.

[0101] Based on the camera's vertical coordinates and the laser's vertical coordinates, the axial offset values ​​of the laser ranging unit and the monocular camera are obtained.

[0102] Based on the above hardware structure, various embodiments of the parameter calibration method for the five-axis motion platform of the present invention are proposed.

[0103] It should be noted that with the rapid development of the smart hardware industry, people have increasingly higher requirements for product user experience, comfort, and appearance. Product forms and appearances are becoming more complex, placing higher demands on the manufacturing industry for these products. This is mainly reflected in the shift from two-dimensional planar processing to three-dimensional processing, smaller product sizes, compact structures, and high precision requirements, leading to increased demand for five-axis equipment. In the identification of mechanical parameters for five-axis machine tools, the conventional approach in the machine tool industry is to use equipment such as ballbars and laser interferometers to measure and model various error parameters of the machine tool. With the development of machine vision technology, the use of vision to identify the mechanical parameters of five-axis equipment is becoming increasingly common. Since monocular cameras struggle to accurately obtain distance information along their axial direction, some researchers use binocular cameras to measure the coordinates of points in three-dimensional space. Others use monocular cameras to capture images and analyze the two-dimensional image information to estimate the camera's axial coordinates. Based on these measured coordinates, the five-axis equipment is then modeled, and the relevant mechanical parameters are solved.

[0104] However, while the method used in the machine tool industry to measure machine tool mechanical parameters using equipment such as ballbars and laser interferometers offers high accuracy, it suffers from high measurement costs and low inspection efficiency. Measuring spatial point coordinates using binocular vision is also problematic due to its larger mechanical structure and relatively higher cost. Furthermore, relying solely on a monocular camera to estimate camera axis coordinates results in insufficient accuracy.

[0105] The precision requirements for five-axis equipment in the manufacturing of the aforementioned products are far less stringent than those for high-precision five-axis machine tools or five-axis machining centers. Therefore, it is unnecessary to calibrate and test five-axis equipment using the methods employed in the machine tool industry. Consequently, it is necessary to find simple, quick, and low-cost methods to model five-axis equipment and identify and compensate for its installation error parameters, thereby improving its precision.

[0106] To address the aforementioned problems, in various embodiments of the parameter calibration method for a five-axis motion platform provided by this invention, a monocular camera and a laser ranging unit are installed on the Z-axis of the five-axis motion platform, wherein the axes of the monocular camera and the laser ranging unit are parallel to the Z-axis; and a calibration plate with calibration points is placed on the first rotation axis of the five-axis motion platform, wherein the axis of the first rotation axis is parallel to the Z-axis. When the first and second rotation axes are respectively given preset rotation angle combinations, the calibration plate exhibits different postures, thereby obtaining the spatial coordinates of each device corresponding to the monocular camera aligning with the calibration points through the monocular camera and the laser ranging unit. Then, the transformation relationship between the device spatial coordinate system and the workpiece coordinate system of the five-axis motion platform is obtained, and the transformation relationship includes an error term. Finally, based on the spatial coordinates of each device, the preset workpiece coordinates of the calibration points, and the transformation relationship, the error parameters of the error term are obtained to achieve the parameter calibration of the five-axis motion platform. This invention completes the calculation and calibration of the error parameters of the five-axis motion platform by combining a laser ranging unit and a monocular camera, effectively reducing calibration costs and improving calibration efficiency. Furthermore, the calibration method of this invention is applicable to most five-axis equipment, has strong universality, and is also conducive to the rapid popularization and application of five-axis equipment.

[0107] Please refer to Figure 2 , Figure 2 This is a flowchart illustrating a parameter calibration method for a five-axis motion platform according to an embodiment of the present invention. It should be noted that although the logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here. In this embodiment, the parameter calibration method for the five-axis motion platform is applied to a five-axis motion platform. A monocular camera and a laser ranging unit are mounted on the Z-axis of the five-axis motion platform, wherein the axial directions of the monocular camera and the laser ranging unit are parallel to the Z-axis; a calibration plate is placed on the first rotation axis of the five-axis motion platform, and calibration points are provided on the calibration plate, wherein the axis of the first rotation axis is parallel to the Z-axis.

[0108] For reference Figure 3 , Figure 3 This is a schematic diagram illustrating an application scenario of an embodiment of the parameter calibration method for the five-axis motion platform of the present invention. A five-axis motion platform generally includes three linear motion axes: X, Y, and Z axes, and two rotary axes. The two rotary axes are the B-axis and the C-axis, where the axis of the B-axis is parallel to the Y-axis, and the axis of the C-axis is parallel to the Z-axis. Due to differences in axis layout and definition, five-axis devices have many variations of the same structure, but their core principles are the same. In this embodiment, the five-axis motion platform can be a dual-turntable type five-axis device, a dual-swing-head type five-axis device, a single-swing-head-single-turntable type five-axis device, etc. Figure 3The five-axis motion platform in this document is a dual-turntable type five-axis device. The following description will use this dual-turntable type five-axis device as an example.

[0109] A monocular camera and a laser ranging unit (such as a point laser position sensor, i.e., "point laser" in the figure) are mounted on the Z-axis of a five-axis motion platform. The axes of both the monocular camera and the laser ranging unit are parallel to the Z-axis. The monocular camera and the laser ranging unit can be mounted side-by-side on the same plane parallel to the Z-axis, or they can be mounted on different planes parallel to the Z-axis. Then, a calibration plate is placed on the first rotational axis of the five-axis motion platform (i.e., the "C-axis" in the figure). The calibration plate has calibration points (i.e., "Mark points" in the figure), and the axis of the first rotational axis is parallel to the Z-axis.

[0110] also, Figure 3 The five-axis motion platform also includes a second rotation axis (i.e., the "B axis" in the figure) representing the RCS (Reference Coordinate System), WCS (Workpiece Coordinate System), XCS (X Coordinate System), YCS (Y Coordinate System), and ZCS (Z Coordinate System).

[0111] The parameter calibration method for a five-axis motion platform provided in this embodiment of the invention includes:

[0112] Step S10: When the first rotation axis and the second rotation axis are each a preset rotation angle combination, the spatial coordinates of each device when the monocular camera is aligned with the calibration point are obtained according to the radial offset value and the axial offset value.

[0113] The rotation angles of the first and second rotation axes can be combined in various ways, resulting in different orientations for the calibration plate on the first rotation axis. When the calibration plate is in any orientation, the X, Y, and Z axes of the five-axis motion platform can be controlled to move until the optical center of the monocular camera aligns with the calibration point on the calibration plate, thus determining the accurate horizontal and vertical coordinates (XY coordinates) of the monocular camera when aligned with the calibration point. Since the monocular camera's alignment in the radial direction (X and Y axes) is accurate, but there is a certain error in the axial direction (Z axis), and the laser ranging unit can accurately determine the axial position, the X, Y, and Z axes can be controlled to move again based on the radial and axial offset values ​​between the monocular camera and the laser ranging unit. At this point, the laser rangefinder's spot aligns with the calibration point. Then, the Z axis is controlled to move until the laser ranging unit's reading reaches the value corresponding to the preset laser height. Then, based on the preset laser height of the laser ranging unit and the axial offset between the monocular camera and the laser ranging unit, the accurate vertical coordinate (i.e., Z-coordinate) of the monocular camera when aligned with the calibration point can be determined. This allows us to obtain the device's spatial position when aligned with the calibration point under that rotation angle combination. Thus, we can obtain the device's spatial coordinates for each preset rotation angle combination when the first and second rotation axes are respectively for each preset rotation angle combination.

[0114] In this embodiment, the radial position is determined by a monocular camera and the axial position is determined by a laser ranging unit, so as to obtain the spatial coordinates of each device when the monocular camera is aligned with the calibration points on different posture calibration plates when the first rotation axis and the second rotation axis are respectively each preset rotation angle combination.

[0115] Furthermore, the procedure before step S10 includes:

[0116] Step A1: Obtain the radial offset and axial offset values ​​of the laser ranging unit and the monocular camera;

[0117] Although the monocular camera and laser ranging unit mounted on the Z-axis of the five-axis motion platform are parallel to the Z-axis axis, their actual installation positions are offset in both the radial (X-axis and Y-axis directions) and axial (Z-axis direction) directions. Therefore, when the rotation angles of the first and second rotation axes are both zero degrees, the radial difference between the two coordinates obtained when the optical center of the monocular camera and the laser spot emitted by the laser ranging unit are aligned with a marker point on the platform can be used to obtain the radial offset value of the laser ranging unit and the monocular camera. For the axial offset, the difference between the camera's vertical coordinate when the optical center of the monocular camera is aligned with a marker point on the platform, and the laser's vertical coordinate when the laser spot emitted by the laser ranging unit at a preset laser height is aligned with the same marker point can be used to obtain the axial offset value of the laser ranging unit and the monocular camera.

[0118] Step S10 includes the following steps:

[0119] Step S11: When the first rotation axis and the second rotation axis are any combination of rotation angles, control the X-axis, Y-axis and Z-axis of the five-axis motion platform to move until the optical center of the monocular camera is aligned with the calibration point to obtain the first spatial coordinates;

[0120] Step S12: Obtain the first alignment coordinates based on the first spatial coordinates, radial offset value, and axial offset value;

[0121] Step S13: Control the X-axis, Y-axis and Z-axis of the five-axis motion platform to move to the first alignment coordinates so that the spot of the laser ranging unit is aligned with the calibration point, and control the Z-axis to move until the reading of the laser ranging unit is the value corresponding to the preset laser height, and obtain the second alignment coordinates;

[0122] Step S14: Based on the second alignment coordinates, radial offset value, and axial offset value, obtain the third alignment coordinates, and use the third alignment coordinates as the device space coordinates corresponding to the rotation angle combination.

[0123] Specifically, the preset laser height is the distance between the laser ranging unit and the calibration point on the calibration plate, such as 70mm, 80mm, or 90mm. This preset laser height can be set according to specific needs. The value corresponding to the preset laser height is determined by the type of laser ranging unit used. Taking a preset laser height of 80mm as an example, if the measurement range of a laser displacement sensor at a certain point is 80±15mm, then its reference measurement distance is 80mm, and the range is ±15mm. Generally speaking, the reading of the laser ranging unit represents the relative deviation from the reference measurement distance. That is, when the actual distance is 80mm, the reading of the laser ranging unit is 0. Of course, a laser ranging unit that displays the actual distance can also be used. In this case, the reading of the laser ranging unit represents the actual measurement distance; that is, if the actual distance is 80mm, then the reading of the laser ranging unit is 80.

[0124] When the first and second rotation axes are any combination of rotation angles (e.g., first rotation axis C = 0°, second rotation axis B = 0°), the X, Y, and Z axes of the five-axis motion platform can be controlled to move until the optical center of the monocular camera aligns with the calibration point. The spatial coordinates of the five-axis motion platform at this point are recorded to obtain the first spatial coordinates. At this time, although the monocular camera is radially aligned with the calibration point, there is still an axial deviation. Since the laser ranging unit can only determine its position on the Z-axis, the first alignment coordinates when the laser ranging unit's spot aligns with the calibration point can be calculated based on the first spatial coordinates, the radial offset value, and the axial offset value. Then, the X, Y, and Z axes of the five-axis motion platform are controlled to move to these first alignment coordinates, thereby aligning the laser ranging unit's spot with the calibration point. The five-axis motion platform is further controlled to move along its Z-axis until the laser ranging unit reads the value corresponding to the preset laser height, thus obtaining the second alignment coordinate. At this point, the Z-axis coordinate corresponding to the preset laser height in the second alignment coordinate is accurate. Therefore, based on the second alignment coordinate, the radial offset value, and the axial offset value, the third alignment coordinate is obtained. This third alignment coordinate is the coordinate of the monocular camera alignment calibration point, and can thus be used as the device space coordinate corresponding to the rotation angle combination. It can be understood that the height of the monocular camera at the alignment calibration point can be the sum of the preset laser height and the axial offset value, the difference between the preset laser height and the axial offset value, or a value obtained by adding or subtracting a preset adjustment value from the sum / difference of the preset laser height and the axial offset value. By recording the device space coordinates of the five-axis motion platform when the monocular camera aligns with the calibration point for each rotation angle combination, the device space coordinates corresponding to each preset rotation angle combination can be obtained when the first and second rotation axes are respectively for each preset rotation angle combination. The equipment space coordinates include the coordinate values ​​of the five-axis motion platform on the X-axis, Y-axis, Z-axis, first rotation axis, and second rotation axis, namely (X,Y,Z,B,C).

[0125] For example, the X, Y, and Z axes of a five-axis motion platform can be controlled to move, thereby aligning the optical center of the monocular camera with the calibration point within the clear field of view of the monocular camera. Then, the radial and axial offset values ​​of the laser ranging unit and the monocular camera are added to the device coordinates of the five-axis motion platform at this point to obtain the first alignment coordinates when the laser ranging unit is aligned with the calibration point. The five-axis motion platform is then controlled to move to these first alignment coordinates, aligning the laser ranging unit with the calibration point. Next, the Z-axis is controlled to move, so that the laser ranging unit's value corresponds to a preset laser height, and the second alignment coordinates are recorded at this point. Finally, the radial and axial offset values ​​are subtracted from the second alignment coordinates to obtain the third alignment coordinates when the monocular camera is aligned with the calibration point.

[0126] In this embodiment, by setting different rotation angles for the first and second rotation axes, the optical center of the monocular camera is first aligned with the calibration point in the manner described above. Then, based on the radial and axial offset values, the point is moved to align the laser rangefinder's spot with the calibration point, and the Z-axis is controlled to move so that the laser rangefinder's value corresponds to the preset laser height. Afterward, the optical center of the monocular camera is aligned with the calibration point again, thus obtaining the device space coordinates of the calibration point under different orientations of the monocular camera's optical center alignment.

[0127] Furthermore, after obtaining the third alignment coordinates based on the second alignment coordinates, radial offset value, and axial offset value in step S14, the method further includes:

[0128] Step S15: Control the X-axis, Y-axis and Z-axis of the five-axis motion platform to move to the third alignment coordinate, and then control the X-axis and Y-axis of the five-axis motion platform to move so that the optical center of the monocular camera is aligned with the calibration point, and obtain the device space coordinates corresponding to the rotation angle combination.

[0129] Because the optical center of a monocular camera may deviate radially when aligning with the calibration point at different heights, after obtaining the third alignment coordinate, the X, Y, and Z axes of the five-axis motion platform can be controlled to move to the third alignment coordinate. Then, the X and Y axes of the five-axis motion platform can be controlled to move so that the optical center of the monocular camera aligns with the calibration point at the vertical coordinate of the third alignment coordinate. At this point, the coordinates of the XYZBC axes of the five-axis motion platform are recorded, thus obtaining a set of equipment space coordinates for the calibration point.

[0130] In this embodiment, after obtaining the third alignment coordinates, the optical center of the monocular camera is controlled to align with the calibration point under the vertical coordinate of the third alignment coordinates, thereby avoiding slight radial differences that may be caused by different heights of the monocular camera, and further improving the accuracy of the spatial coordinates of each device corresponding to each rotation angle combination.

[0131] Step S20: Obtain the transformation relationship between the device space coordinate system and the workpiece coordinate system of the five-axis motion platform, wherein the transformation relationship includes an error term;

[0132] Specifically, a corresponding kinematic model can be established based on the specific structure of the five-axis motion platform. This kinematic model contains multiple error terms. Then, through two error transmission chains of this kinematic model, the workpiece transmission chain is established: base coordinate system (RCS) → Y-axis → B-axis → C-axis → workpiece coordinate system (WCS); and the tool transmission chain is established: base coordinate system (RCS) → X-axis → Z-axis → monocular camera (relative to the tool coordinate system, TCS). The transformation matrices between the coordinate systems of the above two error transmission chains are obtained based on the motion transformation matrix between rigid bodies. Then, based on the above transformation matrices, the transformation relationship between the equipment space coordinate system and the workpiece coordinate system of the five-axis motion platform is obtained. Therefore, the transformation relationship also includes multiple error terms from the above kinematic model.

[0133] Step S20 includes the following steps:

[0134] Step S21: Obtain the workpiece transfer chain error matrix and the tool transfer chain error matrix of the five-axis motion platform;

[0135] Step S22: Based on the workpiece transfer chain error matrix and the tool transfer chain error matrix, obtain the position coordinate expression and pose vector expression in the workpiece coordinate system, and use the position coordinate expression and pose vector expression as the transformation relationship between the equipment space coordinate system and the workpiece coordinate system.

[0136] Specifically, a kinematic model of a five-axis machine tool with error parameters can be established based on homogeneous transformation theory. The main structural error parameters involved in the model are shown in the table below:

[0137] Table 1. Error Parameters of the Kinematic Model of the Five-Axis Motion Platform

[0138]

[0139]

[0140] Among them, PDGE is the error related to the motion axis positioning command, while PIGE is the error unrelated to the motion axis positioning command.

[0141] The five-axis motion model has two error propagation chains:

[0142] Workpiece transfer chain: Base coordinate system (RCS) ---> Y-axis ---> B-axis ---> C-axis ---> Workpiece coordinate system (WCS);

[0143] Tool transfer chain: Base coordinate system (RCS) ---> X-axis ---> Z-axis ---> Monocular camera (relative to tool coordinate system, TCS).

[0144] For the workpiece transfer chain, based on the motion transformation matrix between rigid bodies, the workpiece transfer chain error matrix is ​​as follows:

[0145] The transformation matrix of the Y-axis coordinate system relative to the base coordinate system RCS is:

[0146]

[0147] The transformation relationship from the B-axis coordinate system to the Y-axis coordinate system is as follows:

[0148]

[0149] The transformation relationship from the C-axis coordinate system to the B-axis coordinate system is as follows:

[0150]

[0151] The transformation relationship from the workpiece coordinate system WCS to the C-axis coordinate system is as follows:

[0152]

[0153] For the tool transfer chain, the tool transfer chain error matrix is ​​as follows:

[0154] The transformation matrix from the X-axis coordinate system to the base coordinate system RCS is:

[0155]

[0156] The transformation matrix from the Z-axis coordinate system to the X-axis coordinate system is:

[0157]

[0158] The transformation matrix from the monocular camera coordinate system to the Z-axis coordinate system is:

[0159]

[0160] Therefore, based on the workpiece transmission chain error matrix and the tool transmission chain error matrix, a relational formula can be established to represent the actual pose state in the workpiece coordinate system:

[0161]

[0162]

[0163] Where p w and v w These represent the position coordinates and pose vector in the workpiece coordinate system, respectively.

[0164] Based on the above two relationships, the position and pose vector expressions in the workpiece coordinate system can be obtained as follows:

[0165]

[0166]

[0167] Thus, the transformation relationship between the equipment space coordinate system and the workpiece coordinate system of the five-axis motion platform was obtained, and the transformation relationship includes the error terms corresponding to each error parameter of the five-axis motion platform.

[0168] Step S30: Based on the spatial coordinates of each device, the preset workpiece coordinates of the calibration point, and the transformation relationship, the error parameters of the error term are obtained to achieve parameter calibration of the five-axis motion platform.

[0169] In this embodiment, a workpiece coordinate system can be predefined for the calibration point on the calibration plate, i.e., preset workpiece coordinates. Then, the preset workpiece coordinates of the calibration point and the spatial coordinates of each device are substituted into the transformation relationship to obtain the corresponding nonlinear equation system. For example, the position of the calibration point can be specified as the origin (0,0,0) of the workpiece coordinate system, and the direction vector of the calibration point can be set to (0,0,1). The corresponding nonlinear equation system is described as follows:

[0170]

[0171] Then, by solving the above nonlinear equations, the error parameters of each error term in the transformation relationship can be calculated. It is understandable that the number of spatial coordinates of the device needs to be determined based on the number of error terms in the transformation relationship. For example, if there are 41 error terms, then the corresponding number of spatial coordinates of the device will be at least 41 * 3 = 123.

[0172] Step S30 includes the following steps:

[0173] Step S31: Substitute the spatial coordinates of each device and the preset workpiece coordinates into the position coordinate expression and the pose vector expression to obtain the corresponding nonlinear equation set.

[0174] Step S32: Solve the nonlinear equation system based on Newton's iteration method to obtain the error parameters of the error term;

[0175] Step S33: Update the existing error parameters of the five-axis motion platform according to the error parameters to achieve parameter calibration of the five-axis motion platform.

[0176] Specifically, the spatial coordinates of each device and the preset workpiece coordinates are substituted into the position coordinate expression and pose vector expression to obtain the corresponding nonlinear equation system. Then, the nonlinear equation system is solved based on Newton's iteration method to obtain the error parameters of the error terms. The existing error parameters of the five-axis motion platform are updated according to the error parameters to achieve the parameter calibration of the five-axis motion platform.

[0177] In this embodiment, a monocular camera and a laser ranging unit are mounted on the Z-axis of a five-axis motion platform, with the axes of the monocular camera and the laser ranging unit parallel to the Z-axis. A calibration plate with calibration points is placed on the first rotation axis of the five-axis motion platform, with the axis of the first rotation axis parallel to the Z-axis. The radial and axial offset values ​​of the laser ranging unit and the monocular camera are acquired. Then, when the first and second rotation axes are combined with preset rotation angles, the calibration plate adopts different postures. The accurate radial position for aligning with the calibration points is determined by the monocular camera, and the accurate axial position is determined by the laser ranging unit, thus obtaining the corresponding spatial coordinates of each device when the monocular camera aligns with the calibration points. The transformation relationship between the device spatial coordinate system and the workpiece coordinate system of the five-axis motion platform is then obtained, including an error term. Finally, based on the spatial coordinates of each device, the preset workpiece coordinates of the calibration points, and the transformation relationship, the error parameters of the error term are obtained to achieve parameter calibration of the five-axis motion platform. In this embodiment, the error parameters of the five-axis motion platform are calculated and calibrated by combining a laser ranging unit and a monocular camera. The calibration method in this embodiment has a wide range of applications, high efficiency, and low cost, and is also conducive to the rapid popularization and application of five-axis equipment.

[0178] Furthermore, referring to Figure 4 , Figure 4 This is a schematic diagram of a scenario for obtaining the radial offset values ​​of a laser ranging unit and a monocular camera, as per the present invention. In another embodiment, step A1, obtaining the radial offset values ​​of the laser ranging unit and the monocular camera, includes:

[0179] Step B10: When the rotation angles of the first and second rotation axes of the five-axis motion platform are both zero degrees, control the X and Y axes of the five-axis motion platform to move until the spot of the laser ranging unit just falls into the preset small hole of the same size as the spot on the platform of the five-axis motion platform, and obtain the first laser horizontal and vertical coordinates.

[0180] Step B20: Control the X, Y and Z axes of the five-axis motion platform to move until the optical center of the monocular camera is aligned with the preset small hole, and obtain the horizontal and vertical coordinates of the first camera;

[0181] Step B30: Based on the first laser horizontal and vertical coordinates and the first camera horizontal and vertical coordinates, obtain the radial offset values ​​of the laser ranging unit and the monocular camera.

[0182] Once the monocular camera and laser rangefinder are installed on the Z-axis of the five-axis motion platform, they have a fixed deviation in the radial direction (i.e., the XY axis direction). Due to the influence of depth of field, the monocular camera can produce a clear image of the object being photographed as long as it is within a certain distance along the axis of the optical center. The laser rangefinder typically has a range that fluctuates a certain distance above and below its reference measurement distance. For example, if the measurement range of a laser displacement sensor at a certain point is 80±15mm, then its reference measurement distance is 80mm, and its range is ±15mm. Generally speaking, the reading of the laser detection unit represents the relative deviation from the reference measurement distance. That is, when the actual distance is 80mm, the laser sensor reading is 0. The laser detection unit readings mentioned below all refer to this relative distance.

[0183] In order to obtain the radial offset values ​​of the laser ranging unit and the monocular camera more accurately, the first rotation axis (C-axis) and the second rotation axis (B-axis) of the five-axis motion platform are kept at 0 degrees during the process of obtaining the radial offset values.

[0184] like Figure 4 As shown, firstly, a measuring device is fabricated. This device has a pre-set small hole with a spot size approximately the same as that of the laser ranging unit. This measuring device can be placed on the platform of a five-axis motion platform. Then, the X and Y axes of the five-axis motion platform are controlled to move until the laser ranging unit's spot falls exactly into the pre-set small hole of the same size on the platform's platform, obtaining the first laser coordinates, denoted as (X_laser, Y_laser). Next, the X, Y, and Z axes of the five-axis motion platform are controlled to make the image of the pre-set small hole captured by the monocular camera clear, and the optical center of the monocular camera aligned with the pre-set small hole, obtaining the first camera coordinates, denoted as (X_cam, Y_cam). Finally, the radial offset values ​​of the laser ranging unit and the monocular camera can be obtained based on the difference between the first laser coordinates and the first camera coordinates. For example, DetaX = X_laser - X_cam; DetaY = Y_laser - Y_cam.

[0185] Furthermore, referring to Figure 5 , Figure 5 This is another schematic diagram illustrating the process of obtaining the radial offset values ​​of the laser ranging unit and the monocular camera according to the present invention. The step of obtaining the radial offset values ​​of the laser ranging unit and the monocular camera further includes:

[0186] Step C10: Control the X-axis, Y-axis and Z-axis of the five-axis motion platform to move until the light spot of the laser ranging unit falls on the surface of the preset ball on the platform of the five-axis motion platform and maintains a preset fixed distance from the surface, so as to obtain multiple spherical coordinates of the preset ball.

[0187] Step C20: Perform sphere fitting based on multiple spherical coordinates to obtain the center coordinates of the preset sphere;

[0188] Step C3: Control the X-axis and Y-axis of the five-axis motion platform to move until the optical center of the monocular camera is aligned with the center of the circle on the preset ball image, and obtain the center coordinates;

[0189] Step C40: Based on the coordinates of the sphere center and the circle center, obtain the radial offset values ​​of the laser ranging unit and the monocular camera.

[0190] like Figure 5 As shown, the X and Y axes of the five-axis motion platform are controlled to move until the laser rangefinder's spot falls onto the surface of a preset sphere on the platform. Then, the Z axis is controlled to move until the laser rangefinder's reading corresponds to a preset laser height (e.g., 0°), and the XYZ coordinates of the five-axis motion platform at this point are recorded as spherical coordinates. Multiple spherical coordinates of the sphere are then preset in the same way. Next, spherical fitting is performed on the obtained spherical coordinates to calculate the center coordinates of the preset sphere. Then, the X and Y axes of the five-axis motion platform are controlled to move until, with clear focus, the optical center of the monocular camera aligns with the center of the circle on the preset sphere image, obtaining the center coordinates. The radial offset between the laser rangefinder and the monocular camera can then be obtained based on the radial difference between the sphere center coordinates and the circle center coordinates.

[0191] Furthermore, referring to Figure 6 , Figure 6 This is a schematic diagram illustrating another scenario related to obtaining the radial offset values ​​of the laser ranging unit and the monocular camera, as per the present invention. The step of obtaining the radial offset values ​​of the laser ranging unit and the monocular camera further includes:

[0192] Step D10: Control the X-axis and Y-axis of the five-axis motion platform to move, so that the laser ranging unit scans the first straight line and the second straight line respectively, and obtains multiple first straight line coordinates and second straight line coordinates of the first straight line and the second straight line, wherein the first straight line and the second straight line have an intersection point;

[0193] Step D20: Perform line fitting on multiple first line coordinates to obtain the first line equation, and perform line fitting on multiple second line coordinates to obtain the second line equation;

[0194] Step D30: Based on the equations of the first and second lines, obtain the coordinates of the first intersection point.

[0195] Step D40: Control the X-axis and Y-axis of the five-axis motion platform to move until the optical center of the monocular camera is aligned with the intersection point, and obtain the second intersection point coordinates;

[0196] Step D50: Based on the coordinates of the first intersection point and the second intersection point, obtain the radial offset values ​​of the laser ranging unit and the monocular camera.

[0197] like Figure 6 As shown, a device with two straight, un-beveled edges and good straightness is placed on the platform of a five-axis motion platform, where the two straight edges intersect. The X and Y axes of the five-axis motion platform are then controlled to move, causing the laser ranging unit to scan the first and second straight lines respectively. By recording the X and Y coordinate values ​​at the moment of abrupt change in the laser ranging unit's reading, multiple coordinates of the first straight line and the second straight line are obtained. Then, a linear fit is performed on the multiple first straight line coordinates to obtain the first straight line equation, and the same linear fit is performed on the multiple second straight line coordinates to obtain the second straight line equation. Based on the first and second straight line equations, the first intersection point coordinates are obtained. Next, the X and Y axes of the five-axis motion platform are controlled to move until the optical center of the monocular camera aligns with the intersection point, obtaining the second intersection point coordinates. Finally, the radial offset value between the laser ranging unit and the monocular camera is obtained based on the difference between the first and second intersection point coordinates.

[0198] Furthermore, referring to Figure 7 , Figure 7 This is a schematic diagram of a scene where the optical center of the monocular camera involved in this invention is aligned with a calibration point. The step of obtaining the axial offset values ​​of the laser ranging unit and the monocular camera includes:

[0199] Step E10: Control the X, Y and Z axes of the five-axis motion platform to move until the optical center of the monocular camera is aligned with the calibration point on the calibration plate to obtain the camera's vertical coordinates;

[0200] Step E20: Based on the radial offset value, control the X and Y axes of the five-axis motion platform to move so that the spot of the laser ranging unit is aligned with the calibration point, and control the Z axis of the five-axis motion platform to move until the reading of the laser ranging unit is the value corresponding to the preset laser height, so as to obtain the laser vertical coordinate;

[0201] Step E30: Based on the camera's vertical coordinates and the laser's vertical coordinates, obtain the axial offset values ​​of the laser ranging unit and the monocular camera.

[0202] Reference Figure 7The five-axis motion platform is moved along its X, Y, and Z axes until the optical center of the monocular camera aligns with the calibration point on the calibration plate, thus obtaining the camera's vertical coordinates. Then, based on the obtained radial offset value, the X and Y axes of the five-axis motion platform are moved to align the laser rangefinder's spot with the calibration point. Next, the Z axis of the five-axis motion platform is moved until the laser rangefinder's reading corresponds to the preset laser height, thus obtaining the laser's vertical coordinates. The axial offset between the laser rangefinder and the monocular camera is obtained based on the difference between the camera's vertical coordinates and the laser's vertical coordinates.

[0203] The present invention also provides a computer storage medium storing a parameter calibration program for a five-axis motion platform, wherein when the parameter calibration program for the five-axis motion platform is executed by a processor, the parameter calibration method for the five-axis motion platform as described in any of the above embodiments is implemented.

[0204] The specific embodiments of the computer storage medium of the present invention are basically the same as the embodiments of the parameter calibration method of the five-axis motion platform described above, and will not be repeated here.

[0205] The present invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the parameter calibration method for a five-axis motion platform as described in any of the above embodiments.

[0206] The specific embodiments of the computer program product of the present invention are basically the same as the embodiments of the parameter calibration method of the five-axis motion platform described above, and will not be repeated here.

[0207] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A parameter calibration method for a five-axis motion platform, characterized in that, An application is made to a five-axis motion platform, wherein a monocular camera and a laser ranging unit are mounted on the Z-axis of the five-axis motion platform, wherein the axial directions of the monocular camera and the laser ranging unit are parallel to the Z-axis; a calibration plate is placed on the first rotation axis of the five-axis motion platform, the calibration plate is provided with calibration points, wherein the axis of the first rotation axis is parallel to the Z-axis; The method includes: The radial and axial offset values ​​of the laser ranging unit and the monocular camera are obtained. When the first and second rotation axes are any combination of rotation angles, the X, Y, and Z axes of the five-axis motion platform are controlled to move until the optical center of the monocular camera aligns with the calibration point, thus obtaining the first spatial coordinates. Based on the first spatial coordinates, the radial offset value, and the axial offset value, the first alignment coordinates are obtained. The X, Y, and Z axes of the five-axis motion platform are controlled to move to the first alignment coordinates so that the spot of the laser ranging unit aligns with the calibration point, and the Z axis is controlled to move until the reading of the laser ranging unit is the value corresponding to the preset laser height, thus obtaining the second alignment coordinates. Based on the second alignment coordinates, the radial offset value, and the axial offset value, the third alignment coordinates are obtained, and the third alignment coordinates are used as the device spatial coordinates corresponding to the rotation angle combination. Obtain the transformation relationship between the device space coordinate system and the workpiece coordinate system of the five-axis motion platform, wherein the transformation relationship includes an error term; Based on the spatial coordinates of each device, the preset workpiece coordinates of the calibration point, and the transformation relationship, the error parameters of the error term are obtained to achieve parameter calibration of the five-axis motion platform.

2. The method according to claim 1, characterized in that, After the step of obtaining the third alignment coordinate based on the second alignment coordinate, the radial offset value, and the axial offset value, the method further includes: The X, Y, and Z axes of the five-axis motion platform are controlled to move to the third alignment coordinate, and then the X and Y axes of the five-axis motion platform are controlled to move so that the optical center of the monocular camera is aligned with the calibration point, thereby obtaining the device space coordinates corresponding to the rotation angle combination.

3. The method according to claim 1, characterized in that, The step of obtaining the transformation relationship between the device space coordinate system and the workpiece coordinate system of the five-axis motion platform, wherein the transformation relationship includes an error term, includes: Obtain the workpiece transfer chain error matrix and the tool transfer chain error matrix of the five-axis motion platform; Based on the workpiece transfer chain error matrix and the tool transfer chain error matrix, the position coordinate expression and pose vector expression in the workpiece coordinate system are obtained, and the position coordinate expression and pose vector expression are used as the transformation relationship between the equipment space coordinate system and the workpiece coordinate system.

4. The method according to claim 3, characterized in that, The step of obtaining the error parameters of the error term based on the spatial coordinates of each of the equipment, the preset workpiece coordinates of the calibration point, and the transformation relationship includes: Substituting the spatial coordinates of each device and the preset workpiece coordinates into the position coordinate expression and the pose vector expression, the corresponding nonlinear equation set is obtained; The nonlinear equations are solved using Newton's iteration method to obtain the error parameters of the error term. The existing error parameters of the five-axis motion platform are updated based on the error parameters to achieve parameter calibration of the five-axis motion platform.

5. The method according to claim 1, characterized in that, The step of obtaining the radial offset values ​​of the laser ranging unit and the monocular camera includes: When the rotation angles of the first and second rotation axes of the five-axis motion platform are both zero degrees, the X and Y axes of the five-axis motion platform are controlled to move until the spot of the laser ranging unit just falls into a preset small hole of the same size as the spot on the platform of the five-axis motion platform, and the first laser horizontal and vertical coordinates are obtained. The X, Y, and Z axes of the five-axis motion platform are controlled to move until the optical center of the monocular camera is aligned with the preset small hole, thereby obtaining the horizontal and vertical coordinates of the first camera; The radial offset values ​​of the laser ranging unit and the monocular camera are obtained based on the first laser horizontal and vertical coordinates and the first camera horizontal and vertical coordinates.

6. The method according to claim 1, characterized in that, The step of obtaining the radial offset values ​​of the laser ranging unit and the monocular camera further includes: The X, Y, and Z axes of the five-axis motion platform are controlled to move until the light spot of the laser ranging unit falls on the surface of a preset ball on the platform of the five-axis motion platform and maintains a preset fixed distance from the surface, thereby obtaining multiple spherical coordinates of the preset ball; By performing sphere fitting based on multiple spherical coordinates, the center coordinates of the preset sphere are obtained; The X and Y axes of the five-axis motion platform are controlled to move until the optical center of the monocular camera is aligned with the center of the circle on the preset ball image, and the center coordinates are obtained. The radial offset values ​​of the laser ranging unit and the monocular camera are obtained based on the coordinates of the sphere center and the circle center.

7. The method according to claim 1, characterized in that, The step of obtaining the radial offset values ​​of the laser ranging unit and the monocular camera further includes: The X-axis and Y-axis of the five-axis motion platform are controlled to move, so that the laser ranging unit scans the first straight line and the second straight line respectively, and obtains multiple first straight line coordinates of the first straight line and the second straight line coordinates of the second straight line, wherein the first straight line and the second straight line have an intersection point; A first line equation is obtained by performing line fitting on multiple first line coordinates, and a second line equation is obtained by performing line fitting on multiple second line coordinates. Based on the equations of the first and second lines, the coordinates of the first intersection point are obtained. The X-axis and Y-axis of the five-axis motion platform are controlled to move until the optical center of the monocular camera is aligned with the intersection point, and the second intersection point coordinates of the intersection point are obtained; The radial offset values ​​of the laser ranging unit and the monocular camera are obtained based on the coordinates of the first intersection point and the coordinates of the second intersection point.

8. The method according to claim 1, characterized in that, The step of obtaining the axial offset values ​​of the laser ranging unit and the monocular camera includes: The X, Y, and Z axes of the five-axis motion platform are controlled to move until the optical center of the monocular camera is aligned with the calibration point on the calibration plate, thus obtaining the camera's vertical coordinates; Based on the radial offset value, the X and Y axes of the five-axis motion platform are controlled to move so that the spot of the laser ranging unit is aligned with the calibration point, and the Z axis of the five-axis motion platform is controlled to move until the reading of the laser ranging unit is the value corresponding to the preset laser height, thus obtaining the laser vertical coordinate; The axial offset values ​​of the laser ranging unit and the monocular camera are obtained based on the camera's vertical coordinates and the laser's vertical coordinates.

9. A terminal device, characterized in that, The terminal device includes: a memory, a processor, and a parameter calibration program for a five-axis motion platform stored in the memory and executable on the processor. When the parameter calibration program for the five-axis motion platform is executed by the processor, it implements the steps of the parameter calibration method for the five-axis motion platform as described in any one of claims 1 to 8.

10. A computer storage medium, characterized in that, The computer storage medium stores a parameter calibration program for a five-axis motion platform. When the parameter calibration program for the five-axis motion platform is executed by the processor, it implements the steps of the parameter calibration method for the five-axis motion platform as described in any one of claims 1 to 8.

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