Coordinate Positioning Probe Stand-Off Distance Optimization
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Solution Overview
Problem
Standard measurement parameters for coordinate positioning apparatus often result in sub-optimum performance due to variations in machine characteristics, leading to unnecessarily long stand-off distances that increase measurement cycle times without ensuring required accuracy.
Innovation Solution
A method to calculate an optimum stand-off distance using measured acceleration characteristics of the coordinate positioning apparatus, allowing for reduced measurement times without compromising metrology accuracy, by considering factors like acceleration zones, uncertainty in object positions, and numeric controller response times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard measurement parameters are used for coordinate positioning apparatus, then measurement accuracy is protected, but measurement cycle time increases due to unnecessarily long stand-off distances
Solution Approach 1:
The patent applies parameter changes by calculating an optimized stand-off distance based on the specific acceleration characteristics of each coordinate positioning apparatus. Instead of using fixed standard parameters, the system dynamically determines the stand-off distance by measuring acceleration profiles and computing the distance required for the probe to reach constant velocity before measurement. This customization of parameters resolves the contradiction by eliminating excessive stand-off distances while ensuring measurements are taken only when the probe has stabilized at constant velocity, thus reducing cycle time without compromising accuracy.
2Productivity
If stand-off distance is reduced to decrease measurement cycle time, then productivity improves, but measurement accuracy may be compromised due to acceleration effects
Solution Approach 1:
The patent implements feedback by measuring the actual acceleration characteristics of the coordinate positioning apparatus and using this information to determine the appropriate stand-off distance. The system continuously monitors acceleration profiles during probe movement and uses this feedback to calculate when the probe has reached constant velocity. This feedback mechanism allows the system to optimize stand-off distance for each specific machine, enabling reduced distances that improve productivity while ensuring measurements are only taken when acceleration effects have ceased, thus maintaining accuracy.
3Loss of time
If machine-specific acceleration characteristics are measured and used to calculate optimum stand-off distance, then measurement cycle time is minimized, but device complexity increases due to additional measurement and calculation requirements
Solution Approach 1:
The patent applies self-service by having the coordinate positioning apparatus measure its own acceleration characteristics and perform the calculations needed to determine its optimal stand-off distance. The system uses built-in sensors and processors to capture acceleration profiles during normal operation and computes the optimized parameters without requiring external measurement equipment or complex additional hardware. This self-service approach minimizes the added complexity while achieving the goal of reduced measurement cycle times through customized stand-off distance calculation.
Data Source
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AI summary
A method is described for calculating an optimum stand-off distance (74) for surface position measurements to be acquired by a coordinate positioning apparatus comprising a measurement probe (4). The coordinate positioning apparatus may comprise a machine tool and the measurement probe (4) may comprise a touch trigger probe having a deflectable stylus (12). The method comprises the step of calculating an optimum stand-off distance (74) using at least one measured acceleration characteristic of the coordinate positioning apparatus. In this manner, measurement cycle times may be optimised.