CMM Probe Error Correction via Segmented Translation and Rotation
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Solution Overview
Problem
Coordinate measuring machines face errors in measurement values due to deformation of the moving mechanism during scanning, especially when using probes of different lengths or changing the attitude of the probe, as existing systems fail to accurately calculate correction amounts for position errors.
Innovation Solution
A coordinate measuring instrument with a controller that includes a displacement acquiring unit, a correction-amount calculating unit, and a correcting unit, which calculates and applies translation- and rotation-correction amounts based on displacement, position, velocity, and acceleration to correct position errors, and also accounts for phase differences between movement axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single correction amount is calculated based on acceleration alone, then the correction process is simple, but measurement precision deteriorates when probes of different lengths are used or when probe attitude changes
Solution Approach 1:
The correction amount is segmented into two distinct components: translation correction amount (for position error at reference point) and rotation correction amount (for position error due to probe rotation). This segmentation allows each component to be calculated and applied separately, improving overall correction accuracy while maintaining manageable complexity through modular calculation.
Solution Approach 2:
The correction system dynamically adapts to different probe configurations by calculating rotation correction amounts that vary with probe length and attitude. The system adjusts correction parameters based on the specific probe being used, enabling accurate measurements across multiple probe types without requiring a completely different correction approach for each configuration.
2Productivity
If the same correction amount is applied regardless of probe length or attitude, then the correction process is efficient, but measurement precision deteriorates due to inability to account for probe-specific variations
Solution Approach 1:
The correction system changes parameters (translation correction amount and rotation correction amount) based on probe-specific variables such as probe length and attitude angle. By dynamically adjusting these parameters according to the actual probe configuration, the system maintains high correction efficiency while achieving accurate measurements across different probe types.
Solution Approach 2:
The system incorporates feedback mechanisms where the actual probe configuration (length, attitude) is detected and used to adjust the correction amounts. This feedback loop ensures that the correction process remains efficient by automatically selecting appropriate correction parameters based on the current probe state, while maintaining precision through configuration-specific adjustments.
Data Source
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AI summary
A coordinate measuring machine (1) includes: a probe (21) provided with a measurement piece; a moving mechanism (22) that effects a scanning movement of the probe (21); and a host computer (5) for controlling the moving mechanism (22). The host computer (5) includes a displacement acquiring unit (52) for acquiring a displacement of the moving mechanism (22) and a measurement value calculating unit (53) for calculating a measurement value. The measurement value calculating unit (53) includes a correction-amount calculating unit for calculating a correction amount for correcting a position error of the measurement piece and a correcting unit for correcting the position error of the measurement piece based on the displacement of the moving mechanism (22) and the correction amount. The correction-amount calculating unit calculates a translation-correction amount for correcting a translation error of the probe (21) at a reference point on the probe (21) and a rotation-correction amount for correcting a rotation error of the probe according to a rotation angle of the probe (21) around the reference point and a length of the probe (21) from the reference point to the measurement piece.