Coordinate Measuring Machine Error Map Correction
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Solution Overview
Problem
Existing error correction methods for coordinate positioning apparatus, such as coordinate measuring machines (CMMs), are prone to errors due to difficulties in matching data sets, leading to inaccuracies in positional measurements.
Innovation Solution
A method that calculates an error map by determining positional differences between measurements from two different coordinate positioning apparatus, using known surface normals to correct subsequent measurements, thereby improving positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If error maps are generated by comparing measurements from two coordinate positioning apparatus, then measurement accuracy can be improved, but data set matching becomes prone to errors
Solution Approach 1:
The patent introduces a reference data set as an intermediary element that bridges the two coordinate positioning apparatus. Instead of directly comparing measurements from the two apparatus (which causes matching errors), the reference data set serves as a common intermediary to align and compare measurements, thereby eliminating the harmful matching errors while preserving the accuracy improvement benefit
Solution Approach 2:
The patent segments the measurement correction process into distinct stages: first comparing each apparatus's measurements to the reference data set separately, then combining the results. This segmentation prevents direct problematic comparisons between the two apparatus while maintaining the ability to improve measurement accuracy through reference-based correction
2Measurement precision
If error maps are used to correct subsequent measurements, then positional accuracy improves, but the complexity of the measurement process increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing error maps that describe the differences between measurements from each apparatus and the reference data set. These pre-computed error maps are then applied to subsequent measurements, which simplifies the actual measurement process despite the initial complexity of creating the error maps
Solution Approach 2:
The error maps essentially allow the measurement system to self-correct by automatically applying the pre-computed correction data to new measurements. This self-service mechanism improves positional accuracy without requiring complex real-time calculation or intervention, thereby managing the complexity through automation
Data Source
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AI summary
An error correction method for coordinate positioning apparatus is described. The method comprises (i) taking a first data set comprising one or more first data values, each first data value describing a position on the surface of a first object, (ii) taking a second data set comprising one or more second data values, each second data value describing a position on the surface of the first object, and (iii) calculating an error map comprising one or more error values, each error value describing a positional difference between the surface as described by the first data set and the surface as described by the second data set. The surface normal of the first object is known at each position described by each first data value and step (iii) comprises calculating each error value by determining the positional difference substantially in the direction of the known surface normal.