CMM Probe Temperature Compensation via Normalization Coils
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Solution Overview
Problem
Existing coordinate measurement machines (CMMs) utilizing inductive sensing configurations face issues such as signal/response non-linearities, position offsets, signal drift due to environmental effects, and signal noise, which challenge accurate position sensing of probe tips.
Innovation Solution
The measuring probe for CMMs incorporates a stylus suspension portion, a stylus position detection portion, a disruptor configuration, signal processing and control circuitry, and a temperature dependent compensation portion. This configuration includes field generating and sensing coils, normalization coils, and a conductive disruptor element that moves within a defined motion volume, enabling precise axial and rotary position sensing while compensating for temperature-induced changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inductive sensing configurations are used for position detection, then measurement capability is provided, but signal drift due to environmental effects (temperature changes) occurs
Solution Approach 1:
The patent implements feedback through normalization sensing coils that continuously monitor the magnetic field strength generated by the field generating coil. This feedback signal is used to dynamically adjust and compensate for temperature-induced variations in the inductive sensing system, maintaining signal stability while preserving measurement precision
Solution Approach 2:
The patent compensates for temperature effects by detecting changes in magnetic field parameters (strength and distribution) using normalization coils and adjusting the sensing parameters accordingly. This allows the system to adapt to environmental parameter changes while maintaining reliable position sensing
2Measurement precision
If inductive sensing configurations are used for position detection, then measurement capability is provided, but signal non-linearities and position offsets occur
Solution Approach 1:
Normalization sensing coils provide continuous feedback on the magnetic field distribution, enabling real-time detection and correction of non-linearities and position offsets. This feedback mechanism allows the system to maintain signal linearity and measurement accuracy despite manufacturing tolerances in coil positioning
Solution Approach 2:
The patent uses normalization sensing coils to create a reference copy of the ideal magnetic field distribution. By comparing the actual sensing signals against this reference copy, the system can identify and correct non-linearities and position offsets, improving signal accuracy
3Measurement precision
If inductive sensing configurations are used for position detection, then measurement capability is provided, but signal noise increases
Solution Approach 1:
The normalization sensing coils provide feedback on the actual magnetic field conditions, enabling the system to distinguish between genuine position-related signal variations and noise. This feedback allows for dynamic noise filtering while preserving legitimate measurement signals
Solution Approach 2:
The normalization sensing coils act as intermediaries that measure the magnetic field environment separately from the position sensing coils. This intermediary measurement allows the system to filter out common-mode noise and electromagnetic interference that affects all coils equally, improving signal-to-noise ratio
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution enhances the accuracy and reliability of position sensing in CMMs by mitigating non-linearities, offsets, and environmental effects, thereby improving the precision and consistency of measurements.
Implementation Method 1
A field generating coil generates a changing magnetic flux in response to a coil drive signal
Implementation Method 2
A sensing coil configuration includes top position sensing coils, at least one top normalization sensing coil, bottom position sensing coils, and at least one bottom normalization sensing coil that provide signals having respective signal components that indicate an axial position and a rotary position of the probe tip
Data Source
AI summary
A measuring probe for a coordinate measuring machine is provided. The measuring probe includes a stylus position detection portion, signal processing and control circuitry and a temperature dependent compensation portion. The stylus position detection portion includes a field generating coil configuration and a sensing coil configuration. The temperature dependent compensation portion includes a temperature dependent component that is coupled to a field generating coil of the field generating coil configuration such that a change in a characteristic of the temperature dependent component due to an increase in temperature of the temperature dependent component causes relatively more current to flow through the field generating coil when driven by the coil drive signal than if the characteristic of the temperature dependent component had not changed. Such implementations are configured to increase the accuracy of the processed signals by at least partially compensating for certain affects that occur due to temperature changes.