Coordinate Measuring Machine Probe Asymmetry Correction
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Solution Overview
Problem
Conventional coordinate measuring machines face challenges in accurately correcting asymmetric probe characteristics, leading to potential inaccuracies in obtaining shape coordinates due to insufficient correction of symmetric change characteristics in measuring probes.
Innovation Solution
A coordinate measuring machine and method that involve a measuring probe, a drive mechanism, and a processing device with a calibration artifact, where the measurement tip is brought into contact in five directions, including three perpendicular directions and two inverse directions, to generate a correction matrix for improving probe output accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressing measurement is performed only on one end side in three directions using conventional correction matrix method, then the correction process is simple, but the asymmetric probe characteristics cannot be sufficiently corrected
Solution Approach 1:
The correction measurement is segmented into two distinct parts: pressing measurement (5 directions) and scanning measurement (3 directions). This segmentation allows each measurement type to target specific aspects of probe characteristics, with pressing measurement addressing asymmetric characteristics and scanning measurement addressing symmetric characteristics, thereby resolving the contradiction between correction accuracy and complexity
Solution Approach 2:
The invention extends the correction measurement from the conventional 3-direction pressing measurement to a 5-direction pressing measurement by adding two inverse directions. This dimensional expansion enables comprehensive capture of asymmetric probe characteristics in both positive and negative directions, significantly improving shape coordinate accuracy while maintaining manageable measurement complexity
2Measurement precision
If five-direction pressing measurement and three-direction scanning measurement are performed, then asymmetric probe characteristics are sufficiently corrected, but the measurement time increases
Solution Approach 1:
The pressing measurement in five directions is performed as a preliminary action before the scanning measurement in three directions. By establishing the correction matrix through pressing measurement first, the subsequent scanning measurement can focus on refining the correction, thereby optimizing the overall calibration time while achieving sufficient correction accuracy
Solution Approach 2:
The measurement process uses periodic reciprocating motion in the scanning measurement phase, where the measurement tip moves back and forth along predetermined paths. This periodic action efficiently collects data for symmetric probe characteristics while maintaining measurement speed, balancing accuracy improvement with time loss
Data Source
AI summary
A processing device includes: a pushing drive mechanism control unit that brings a measurement tip into contact with a surface of a calibration artifact at a single point in each of five directions are all normal directions to the surface of the calibration artifact; a scanning drive mechanism control unit that reciprocates the measurement tip on the surface of the calibration artifact on each of three planes perpendicular to one another; a coordinate acquisition unit that acquires a moving amount and a probe output of a measuring probe; a matrix generation unit that generates a correction matrix; and a probe output correction unit that corrects the probe output with the correction matrix. This enables an improvement in asymmetric probe characteristics of the probe output, which is outputted from the measuring probe, in a particular plane. Thus, shape coordinates of an object to be measured can be obtained with high accuracy.