Research on the Method of the Calibration of 3D Scanning Probe System Based on the Least Squares of Subsection-Variable Parameters

Traditional one-dimensional, two-dimensional probe can only measure the micro displacement in one or two directions of space, therefore highly-efficient and highly-precise measurement requirements of the surface of the complex gear can’t be satisfied. Because 3D scanning probe can measure the micro-displacement in three mutually perpendicular directions of space, with it, continuous scanning motion measurement can be achieved and a large number of data points in three directions of space can be measured in a very short time, it is widely used in gear measurement industry at home and abroad. However, because of the limitations of mechanical structure of 3D scanning probe, installation errors and environmental factors, the measured three directions can’t always be strictly vertical, and in the measurement, there will be the interference and the coupling phenomenon among the three directions. The study about how to ensure the highly precise characteristics of 3D scanning probe using a reasonable calibration method has become hot and difficult. In the paper, a new calibration method is proposed, the different regions on the standard ball were continuously contacted by 3D scanning probe, and let the probe step 10 times on the each contact point of standard ball, 10 group of points data were read out. The point of subsection was determined based on the deformation of the probe in the experiment, the data of the probe collected in each segment were fitted by using of the least squares method. Several calibration matrices were so obtained, the precise calibration of 3D scanning probe can be achieved. This method is finally verified by experiment. The experimental results show that the method of calibration is feasible, and has the advantages of high-speed and high-precision, which lays a solid foundation for high-precision measurement of 3D scanning probe.