Scanning Probe Surface Texture Measurement Correction Filter
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Solution Overview
Problem
Existing scanning probe measurement technologies face errors due to kinetic issues like quadrant projection, backlash, and transient vibrations, which are not fully corrected by existing methods, leading to inaccuracies in measuring surface texture, especially for objects with complex shapes like cylinders and pistons.
Innovation Solution
A measuring apparatus with a scanning probe, slider, scale unit, stylus tip displacement detector, and an arithmetic unit that applies a correction filter based on relative displacement characteristics to calculate precise measurements by accounting for kinetic errors and frequency transfer characteristics, effectively reducing measurement errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a scanning probe is used to measure surface texture, then measurement capability is achieved, but kinetic errors such as quadrant projection and backlash occur reducing measurement precision
Solution Approach 1:
The patent applies feedback by using accelerometers to detect vibration and acceleration of the probe head, then using this information to calculate and correct measurement errors in real-time. The correction values are computed based on the detected acceleration and frequency transfer characteristics, and these corrections are applied to the raw measurement data to eliminate kinetic errors.
Solution Approach 2:
The patent replaces purely mechanical measurement with a hybrid system that incorporates electronic sensors (accelerometers) and computational correction. Instead of relying solely on mechanical stability, the system uses electronic detection of kinetic errors and mathematical correction to achieve high measurement precision despite mechanical vibrations and backlash.
2Measurement precision
If measurement is taken at very low slider speed, then fine surface details can be captured, but stick-slip phenomenon occurs causing measurement errors
Solution Approach 1:
The system uses accelerometers to detect stick-slip motions and vibrations during low-speed slider movement. By monitoring the acceleration signals, the system identifies stick-slip events and applies correction values to compensate for the resulting measurement errors, enabling accurate surface texture measurement even at very low speeds.
Solution Approach 2:
The patent changes the measurement approach by incorporating acceleration-based correction parameters. Instead of relying solely on position data from the scale unit, the system introduces acceleration measurements and frequency transfer characteristics as additional parameters to correct for stick-slip and vibration effects during low-speed operation.
3Measurement precision
If existing correction methods are applied to eliminate inertia errors, then some measurement accuracy is improved, but projection-like errors and other kinetic errors remain
Solution Approach 1:
The patent implements comprehensive feedback by using accelerometers to detect all types of kinetic errors (vibrations, accelerations, stick-slip) and applying correction values based on frequency transfer characteristics. This goes beyond existing methods that only correct inertia errors by incorporating real-time acceleration feedback to eliminate projection-like errors and other kinetic errors.
Solution Approach 2:
The patent performs preliminary characterization of the measurement system by determining frequency transfer characteristics between the scale unit and probe head before actual measurements. These pre-determined correction parameters are then applied during measurement to proactively correct various kinetic errors including projection-like errors, vibrations, and stick-slip phenomena.
Data Source
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AI summary
An arithmetic unit 212 is a correction filter 212a based on the relative displacement characteristics between a scale unit 19b and the end of a slider 16, and calculates a measured value by adding up together the displacement of the stylus tip 17a and a value found by applying the correction filter 212a to the displacement of the slider 16 detected by the scale unit 19b.