CN-121761761-B - Spectrum confocal probe pose calibration method and device based on plane constraint

CN121761761BCN 121761761 BCN121761761 BCN 121761761BCN-121761761-B

Abstract

The invention provides a planar constraint-based spectral confocal probe pose calibration method and a planar constraint-based spectral confocal probe pose calibration device, which belong to the technical field of precision measurement and instruments, wherein the method comprises the steps of firstly, measuring at least three non-coplanar planar standard components by using a contact measuring head, and accurately establishing an equation of each standard plane under a machine coordinate system through coordinate conversion and fitting; then, the same plane piece is measured by using a spectral confocal probe, the obtained measuring point coordinates and distance values are combined with a known plane equation, a linear overdetermined equation set of probe pose parameters (comprising an optical axis direction vector and a space position vector) is constructed, and finally, the equation set is solved by a least square method, so that accurate pose parameters are obtained. The invention converts the nonlinear problem into linear solution, avoids iterative calculation, and remarkably improves the calibration efficiency and precision. Meanwhile, plane constraint is utilized to allow the measuring points to be uniformly distributed, so that the pathogenicity of the equation set is effectively reduced, and the robustness of the calibration process is enhanced.

Inventors

LU WENLONG
YUAN KANG
CHANG SUPING

Assignees

华中科技大学

Dates

Publication Date: 20260508
Application Date: 20260303

Claims (10)

1. The method for calibrating the pose of the spectral confocal probe based on plane constraint is characterized by comprising the following steps of: establishing a coordinate system comprising a three-coordinate machine coordinate system, a contact probe coordinate system, a spectrum confocal probe coordinate system and a standard plane coordinate system; Determining position parameters of the spectral confocal probe to be calibrated by conversion between a coordinate system of the spectral confocal probe and a coordinate system of a three-coordinate machine, wherein the position parameters comprise an optical axis direction vector and a spatial position vector, the optical axis direction vector is a vector formed by directional cosine of included angles of three coordinate axes of the optical axis and the coordinate system of the spectral confocal probe, and the spatial position vector is an offset vector of an origin of the coordinate system of the spectral confocal probe relative to an origin of the coordinate system of the machine; Measuring at least three non-coplanar plane standard components by using the contact type measuring head, measuring a plurality of non-collinear points on each plane standard component, converting the coordinates of the measuring points from a contact type measuring head coordinate system to a three-coordinate machine coordinate system, and fitting to obtain a corresponding plane equation under the three-coordinate machine coordinate system; And measuring the at least three non-coplanar plane standard components by using a spectral confocal probe, recording a coordinate value displayed by a three-coordinate machine corresponding to each measuring point and a distance value measured by the spectral confocal probe, combining the coordinate value and the distance value with a corresponding plane equation, constructing a linear equation set related to pose parameters, and solving the linear equation set to obtain the pose parameters.
2. The planar constraint-based spectroscopic confocal probe pose calibration method according to claim 1, wherein establishing a coordinate system comprising a three-coordinate machine coordinate system, a contact probe coordinate system, a spectroscopic confocal probe coordinate system and a standard planar coordinate system comprises: setting an origin of a coordinate system of a three-coordinate machine as a machine zero point of the three-coordinate measuring machine, wherein a coordinate axis is parallel to a movement direction of a machine guide rail; Setting an origin of a contact type measuring head coordinate system as a point center of a tip of a measuring needle, wherein a coordinate axis is parallel to a coordinate axis of a machine coordinate system; The origin of the coordinate system of the spectral confocal probe is set as the starting point of the measuring range of the spectral confocal probe, and the coordinate axis is parallel to the coordinate axis of the coordinate system of the machine.
3. The planar constraint-based spectroscopic confocal probe pose calibration method according to claim 1, wherein said step of fitting a plane equation specifically comprises: selecting at least three non-collinear measuring points for each plane standard component; substituting coordinates of each measuring point under a three-coordinate machine coordinate system into a plane equation; and constructing an overdetermined linear equation set and solving the overdetermined linear equation set to determine plane equation parameters corresponding to the plane standard component.
4. The planar constraint-based spectroscopic confocal probe pose calibration method of claim 1, wherein said step of constructing a system of linear equations specifically comprises: defining pose parameters to be calibrated, wherein the direction vector of the optical axis is The spatial position vector is , For the components of the optical axis direction vector along the X, Y, Z axes in the spectral confocal probe coordinate system, The components of the X, Y, Z axes of the spatial position vector under a three-coordinate machine coordinate system are respectively; For the ith measurement point on the kth standard plane, displaying coordinates according to a three-coordinate machine Distance value measured by spectral confocal probe And plane equation parameters corresponding to the plane standard , , And And (3) establishing an equation: 。
5. the planar constraint based spectral confocal probe pose calibration method of claim 4 wherein solving a system of linear equations to obtain pose parameters comprises: let the parameter vector to be solved The equation corresponding to each measuring point is arranged into a linear form ; Wherein, the , ; Stacking P and Q of all measurement points to form matrix P and vector Q respectively by the formula And solving pose parameters.
6. The planar constraint-based spectroscopic confocal probe pose calibration method according to claim 1, wherein said measurement points are uniformly distributed over the entire plane.
7. The planar constraint-based spectroscopic confocal probe pose calibration method according to claim 1, wherein the spectroscopic confocal probe and the contact probe are integrated into a composite probe and are mounted on a three-coordinate measuring machine with a turntable.
8. The planar constraint-based spectral confocal probe pose calibration method of claim 1, further comprising: Determining conversion information for converting the measurement points of the spectral confocal probe into a three-coordinate machine coordinate system; and realizing coordinate conversion of the measurement points according to the solved pose parameters and the conversion relation.
9. The utility model provides a spectral confocal probe position appearance calibration device based on plane constraint which characterized in that includes: The first processing module is used for establishing a coordinate system comprising a three-coordinate machine coordinate system, a contact probe coordinate system, a spectrum confocal probe coordinate system and a standard plane coordinate system; the second processing module is used for determining the pose parameters of the spectral confocal probe, which are required to be calibrated, for conversion between the coordinate system of the spectral confocal probe and the coordinate system of the three-coordinate machine, wherein the pose parameters comprise an optical axis direction vector and a spatial position vector, the optical axis direction vector is a vector formed by the direction cosine of the included angle of the optical axis and the three-coordinate axis of the coordinate system of the spectral confocal probe, and the spatial position vector is an offset vector of the origin of the coordinate system of the spectral confocal probe relative to the origin of the coordinate system of the machine; the third processing module is used for measuring at least three non-coplanar plane standard components by using the contact type measuring head, measuring a plurality of non-collinear points on each plane standard component, converting the coordinates of the measuring points from a contact type measuring head coordinate system to a three-coordinate machine coordinate system, and fitting to obtain a plane equation corresponding to each plane standard component under the three-coordinate machine coordinate system; And the fourth processing module is used for measuring the at least three non-coplanar plane standard components by using the spectral confocal probe, recording the coordinate values displayed by the three coordinate machines corresponding to each measuring point and the distance values measured by the spectral confocal probe, combining the coordinate values and the distance values with the corresponding plane equations, constructing a linear equation set related to the pose parameters, and solving the linear equation set to obtain the pose parameters.
10. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the planar constraint based spectroscopic confocal probe pose calibration method according to any one of claims 1 to 8 when the computer program is executed by the processor.

Description

Spectrum confocal probe pose calibration method and device based on plane constraint Technical Field The invention relates to the technical field of precision measurement and instruments, in particular to a method and a device for calibrating the pose of a spectrum confocal probe based on plane constraint. Background The spectral confocal probe is a high-precision non-contact measurement sensor based on an optical dispersion principle and a confocal technology, and is usually clamped on a three-coordinate measuring machine when the spectral confocal probe is applied to industry, and the three-coordinate measuring machine is utilized to drive the spectral confocal probe to carry out mobile measurement. The position and orientation calibration error of the spectral confocal probe can directly influence the measurement precision, and in order to accurately measure the spectral confocal probe, the position and orientation of the spectral confocal probe needs to be calibrated. The method for calibrating the optical confocal probe mostly adopts a pose calibration method based on a standard sphere, and the pose parameters of the sensor are solved by fitting the sphere center with the standard sphere through multi-angle measurement. When the method is used for calibration, because the angle measured by the standard ball and the measuring point range are smaller, when the pose parameter is solved by the equation set, the calibration precision is reduced due to the mutual coupling of the space position and the light beam direction when the pose parameter is solved. The spectral confocal probe and the contact probe are combined into a set of composite probe, a set of multi-degree-of-freedom scanning device based on a three-coordinate measuring machine is constructed and used for measuring the profile size and the appearance of the aviation blade, as shown in fig. 1, and fig. 1 is a schematic structural diagram of the aviation blade measuring system. The device integrates a turntable and a spectral confocal sensor on the basis of a contact type three-coordinate measuring machine to construct a spectral confocal blade measuring system. The turntable is arranged on a marble platform of the three-coordinate measuring machine, and forms a four-axis linkage measurement scanning system with the three-coordinate measuring machine, and the spectral confocal probe and the contact probe are combined into a composite probe, so that a definite spatial position relationship is established between the spectral confocal probe and the contact probe. In an ideal case, the spectral confocal probe and the contact scanning probe of the three-coordinate measuring machine form a contact-non-contact composite scanning probe, the beam direction of the optical measuring head is consistent with the Y-axis direction of the machine tool, and the spectral confocal probe and the trigger measuring head carried by the CMM have fixed relative positions. However, because the positioning reference of the spectral confocal probe is inaccurate during installation, eccentricity and inclination angle are inevitably generated, the installation errors reduce the measurement precision, and the absolute coordinates of the workpiece in space cannot be solved due to unknown zero positions, so that the pose of the spectral confocal probe is required to be calibrated. Disclosure of Invention The measuring system is required to calibrate the pose of the optical confocal probe, and the scheme of the composite measuring head is adopted in the system, the invention provides a method and a device for calibrating the pose of a spectral confocal probe based on plane constraint, which simplify the operation method of calibration and improve the precision and the robustness of the pose calibration of the spectral confocal probe. The invention provides a plane constraint-based spectral confocal probe pose calibration method, which comprises the steps of establishing a coordinate system comprising a three-coordinate machine coordinate system, a contact type measuring head coordinate system, a spectral confocal probe coordinate system and a standard plane coordinate system, determining spectral confocal probe pose parameters which need to be calibrated in a conversion mode between the spectral confocal probe coordinate system and the three-coordinate machine coordinate system, wherein the pose parameters comprise an optical axis direction vector and a spatial position vector, the optical axis direction vector is a vector formed by directional cosine of an included angle of a three coordinate axes of the optical axis and the spectral confocal probe coordinate system, the spatial position vector is a displacement vector of an origin of the spectral confocal probe coordinate system relative to the origin of the machine coordinate system, measuring at least three non-coplanar plane standard components by using the contact type measuring head, measuring a plurality of non-collinear