A Quasi-Morphological Filtering Method for Extracting 2D Profiles in Touch Probe Measurement

Abstract

The invention discloses a quasi morphological filtering method for extracting a two-dimensional contour in contact measuring head measurement and belongs to the field of precision measurement technology and instrument technology. According to the quasi morphological filtering method for extracting the two-dimensional contour in contact measuring head measurement, the envelope lines of measuring head contour lines of the positions corresponding to all direct measured data points serve as a final two-dimensional contour measurement result. According to the method, in the two-dimensional contour extracting process, the normal direction in the contact point position does not need to be estimated, and therefore the method is particularly applicable to the situation that in precise measurement, the curvature change of a measured contour is large and even the measured contour is unsmooth.

Description

technical field [0001] The present invention is a method of extracting the two-dimensional measurement of the measured workpiece from the measurement data when the contact probe is used to measure the precision-processed mechanical parts on precision measuring instruments such as a three-coordinate measuring machine, a gear measuring center, and a gear overall error measuring instrument. The contour method belongs to the field of precision testing technology and instrument technology. Background technique [0002] The probes used in precision measuring instruments such as three-coordinate measuring machines, gear measurement centers, and gear overall error measuring instruments can be divided into two types: contact probes and non-contact probes, with contact probes being the most common. The end profile of the probe used is spherical, inverted cone, disc, cone, involute, etc., and the spherical shape is the most common. For the convenience of description, the above-mention...

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Problems solved by technology

There are two disadvantages of this method: First, the curve fitting process is to optimize the whole of the direct measurement data, and the fitting result is not the best approximation for some parts, which will cause the radius of the probe at some positions The maximum value of the compensation error becomes larger; secondly, the approximate curve equation that this method needs to obtain must be first-order derivable, when the curvature of the probe center trajectory represented by the direct measurement data obtained by actual measurement changes greatly , the interpolation curve will appear "Runge" phenomenon, the obtained curve equation will oscillate, the normal direction estimated at the direct measurement data point will produce great distortion, and the probe radius compensation error will also increase sharply

[0007] The core idea of ​​the three-point co-circle method, as well as the triangular patch method and four-point co-sphere method in three-dimensional compensation is to use multiple direct measurement data in the vicinity of the actual measured point to estimate the normal direction of the measured point. Its defect is that there is no unified rule on how to select the data involved in the calculation, the results obtained by selecting different data will be very different, and the correctness of the estimated normal direction cannot be confirmed, so the validity of the compensation result cannot be guaranteed

The disadvantage of this method is that there is relative sliding between the probe and the surface of the workpiece during scanning measurement, and the resulting friction will significantly affect the direction of the measurement force, thereby affecting the accuracy of probe radius compensation

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