Shape Measuring Machine Multi-Filter Error Correction
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Solution Overview
Problem
Existing shape measuring machines, such as coordinate measuring machines, face measurement errors due to quadrant projections caused by mechanical structure backlashes, which cannot be fully corrected by existing methods, especially when the scanning probe's response is poor and the reference position of the tip sphere fails to follow the slider's movement.
Innovation Solution
A shape measuring machine with a scanning probe, a movable slider, a scale unit, and a tip sphere displacement detection unit, utilizing a multi-filter correction system to correct measurement errors by accounting for frequency transfer characteristics from the scale unit to the tip sphere, and further refining corrections based on characteristics from the scanning probe to the stylus attachment, effectively reducing measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single correction filter based on frequency transfer characteristic from scale to slider tip is used, then measurement error due to frequency transfer characteristic is reduced, but measurement error due to relative displacement between slider tip and probe tip sphere reference position cannot be eliminated
Solution Approach 1:
The correction filter is divided into two separate filters: a first correction filter that processes frequency transfer characteristics from the scale to the slider tip, and a second correction filter that processes frequency transfer characteristics from the slider tip to the probe tip sphere reference position. This segmentation allows each filter to independently address specific sources of measurement error, thereby improving overall correction effectiveness and measurement precision.
2Speed
If the scanning probe response is poor, then the reference position of tip sphere cannot follow the movement of slider tip, but existing correction methods cannot account for this relative displacement
Solution Approach 1:
The system measures the actual frequency transfer characteristics from the slider tip to the probe tip sphere reference position and uses this measured data to configure the second correction filter. This feedback approach ensures that the correction filter accurately compensates for relative displacement even when the probe response is slow, maintaining measurement precision by adapting to the actual dynamic behavior of the probe system.
Data Source
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AI summary
A shape measuring machine includes a slide that supports a scanning probe. A scale unit detects a displacement of the slider. A tip sphere displacement detection unit detects a displacement of the tip sphere. A calculation unit includes a correction filter including a first and second tilters and an adder, and calculates a measurement value from the displacements of the slider and the tip sphere. The first filter corrects the displacement of the slider based on a frequency transfer characteristic from the scale unit to the tip of the slider. 'I'he second filter outputs a value that is obtained by correcting a value corrected by the first filter based on a frequency transfer characteristic from the tip of the slider to the tip sphere as the correction value. The adder outputs a measurement value obtained by adding the correction value and the displacement of the tip sphere.