Coordinate Positioning Apparatus Feature-Based Error Correction
Solution Overview
Problem
Existing methods for correcting measurement errors in coordinate positioning apparatus require complex point-by-point error mapping, which is difficult to implement and align, especially in production environments with frequent recalibration needs due to temperature variations.
Innovation Solution
A method that determines a geometric correction value for a series of nominally identical parts by measuring a reference part and applying that value to subsequent parts, eliminating the need for large point-by-point error maps and simplifying the correction process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If point-by-point error mapping is used to correct measurement errors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the complex point-by-point error correction process into a simplified feature-based correction approach. Instead of correcting every measurement point individually, the system identifies key geometric features (planes, cylinders, spheres, cones) and applies corrections at the feature level. This segmentation reduces the computational complexity and data processing requirements while maintaining measurement accuracy.
Solution Approach 2:
The patent extracts the essential correction information from complex point-by-point error maps by focusing on characteristic geometric features. By taking out only the necessary correction data associated with specific features rather than all measurement points, the system reduces the burden of error map generation and application while preserving the critical correction information needed for accurate measurements.
2Measurement precision
If point-by-point error maps are generated and stored, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary identification and characterization of geometric features during the initial measurement process. By pre-identifying features such as planes, cylinders, spheres, and cones and associating correction data with these features beforehand, the system eliminates the need for time-consuming point-by-point error map generation during recalibration. This preliminary action significantly reduces the time required for error correction while maintaining accuracy.
3Measurement precision
If identical measurement control software is installed on multiple CMMs for point-by-point comparison, then measurement precision is improved, but ease of operation worsens
Solution Approach 1:
The patent develops a universal feature-based correction methodology that can be applied across different CMM systems and measurement scenarios. By creating a correction approach that works with various geometric features and measurement types rather than requiring system-specific point-by-point procedures, the invention improves ease of operation while maintaining measurement accuracy across different platforms.
4Measurement precision
If frequent recalibration is performed in production environments, then measurement precision is maintained, but productivity decreases
Solution Approach 1:
The patent performs preliminary feature identification and correction parameter extraction during normal measurement operations. By preparing correction data in advance through automated feature recognition rather than requiring time-consuming manual error map generation during recalibration, the system enables faster recalibration cycles that maintain measurement precision without significantly impacting production productivity.
Data Source
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Figure 3a~4
Figure 5A~5C
AI summary
A method of operating coordinate positioning apparatus having a measurement probe (18) is described. The method comprising a step of taking a first part (24) in a series of nominally identical parts, at least a first reference geometrical property associated with one or more features of the first part (24) being known. A step is also performed of using the coordinate positioning apparatus to measure the one or more features of the first part (24) and determining therefrom a first measured geometrical property that corresponds to the first reference geometrical property. A first property correction value is then determined that describes a difference between the first reference geometrical property and the first measured geometrical property. The coordinate positioning apparatus is then used to measure the one or more features of one or more further parts in the series of nominally identical parts and, for each further part, a further measured geometrical property is determined that corresponds to the first reference geometrical property. The first property correction value is then applied to each further measured geometrical property. A corresponding coordinate positioning apparatus is also described.