Form Measuring Instrument Stylus Transfer Function Error Compensation
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Solution Overview
Problem
Form measuring instruments fail to compensate measurement errors based on the motion history of the probe, leading to inaccuracies due to the neglect of probe motion characteristics.
Innovation Solution
A form measuring instrument that includes a probe with a stylus tip, a detector to track the probe's position, and a measurement value calculator using a transfer function to calculate the contact position of the stylus tip, which compensates for measurement errors by applying digital filters to the probe's position data, thereby improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods are used without considering probe motion characteristics, then the device complexity is low, but measurement precision deteriorates due to uncorrected phase delays and motion history errors
Solution Approach 1:
The patent replaces mechanical correction methods with a mathematical approach using transfer functions and digital filtering. Instead of physically compensating for probe motion effects through mechanical means, the system uses signal processing to filter out motion-induced errors from the measurement data, thereby improving accuracy without adding mechanical complexity
Solution Approach 2:
The patent introduces transfer functions and digital filters as intermediary elements between the probe and the measurement output. These intermediaries process the raw measurement signals to eliminate phase delays and motion history effects, acting as a bridge that transforms inaccurate raw data into corrected measurement values without requiring direct physical modification of the probe
2Measurement precision
If compensation methods based on Hertzian elastic contact theory are used, then measurement precision improves slightly, but measurement precision deteriorates because motion characteristics and phase delays are still not considered
Solution Approach 1:
The patent implements feedback by using the measured position of the probe and applying transfer functions that account for the probe's motion characteristics. The system continuously monitors probe position and dynamically corrects measurements based on the relationship between probe position and stylus contact position, creating a closed-loop correction mechanism that improves both accuracy and reliability
Solution Approach 2:
The patent performs preliminary characterization of the probe's motion characteristics by determining transfer functions that describe the relationship between probe position and stylus contact position. This preliminary analysis allows the system to pre-calculate correction factors that are then applied during actual measurements, preventing errors before they affect the final results
3Measurement precision
If additional hardware is added to implement transfer functions, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent replaces potential hardware additions with software-based signal processing. Instead of adding physical components to implement transfer functions, the system uses digital filtering and mathematical calculations performed by the measurement value calculator, achieving the same error correction effect without increasing hardware complexity
Solution Approach 2:
The patent creates a mathematical model (transfer function) that copies and represents the probe's motion characteristics. This virtual model allows the system to simulate and correct for motion effects through calculation rather than requiring physical sensors or additional measurement devices, thereby maintaining hardware simplicity while improving accuracy
Data Source
AI summary
A form measuring instrument includes an instrument body and a controller that controls the instrument body. The instrument body includes a probe. The probe includes: a rod-like stylus having a distal end attached with a stylus tip for contacting with an object; and a support mechanism that supports the base end of the stylus. The support mechanism includes a probe sensor that detects the position of the stylus and supports the stylus in a manner movable within a predetermined range. The controller calculates a measurement value based on a transfer function whose input is the position of the stylus detected by the probe sensor and output is the contact position of the stylus tip against the object.