CMM Probe Sensing Coils for Temperature-Drift Compensation
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Solution Overview
Problem
Inductive sensing configurations in coordinate measurement machines (CMMs) face issues such as signal non-linearities, position offsets, signal drift due to temperature changes, and signal noise, which affect the accuracy of probe tip deflection measurements.
Innovation Solution
The implementation of a measuring probe with a drive mechanism and attachment portion, utilizing a field generating coil configuration and sensing coil portion that includes rotary and axial sensing coils, along with normalization sensing coils to compensate for temperature-dependent signal variations, ensuring accurate position detection.
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 temperature changes and environmental effects occurs
Solution Approach 1:
The patent implements feedback by continuously monitoring temperature changes and environmental conditions, then using this information to dynamically adjust the inductive sensing measurements. Temperature sensors and environmental sensors provide feedback signals that are processed to compensate for drift in the inductive position detection signals, maintaining measurement accuracy over time and varying conditions.
Solution Approach 2:
The patent applies parameter changes by adjusting the operating parameters of the inductive sensing system based on temperature and environmental conditions. This includes modifying excitation frequencies, signal amplification gains, and measurement timing to compensate for temperature-dependent changes in inductive coupling and electromagnetic interference, thereby maintaining signal stability across different operating conditions.
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:
The patent applies preliminary action by performing calibration and characterization of the inductive sensing system before actual measurements. During this preliminary phase, the system maps the relationship between disruptor position and sensing coil signals under various conditions, storing calibration data that is used to correct non-linearities and position offsets during normal operation, thereby improving signal linearity without sacrificing measurement capability.
3Measurement precision
If inductive sensing configurations are used for position detection, then measurement capability is provided, but signal noise increases
Solution Approach 1:
The patent uses intermediary elements including magnetic shields and conductive disruptors that mediate the interaction between the inductive sensing coils and the external environment. These intermediaries protect the sensing system from electromagnetic interference and noise while allowing the desired position detection function to operate, effectively filtering out harmful electromagnetic signals without blocking the measurement capability.
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 solution enhances the precision of CMM measurements by minimizing signal variations due to temperature changes and environmental effects, improving the accuracy and reliability of probe tip position sensing.
Implementation Method 1
A field generating coil generates a changing magnetic flux encompassing the disruptor and coils
Implementation Method 2
coil signals indicate the disruptor and/or stylus position
Data Source
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AI summary
A measuring probe for a coordinate measuring machine is provided. The measuring probe includes a stylus position detection portion with a sensing coil configuration, signal processing and control circuitry and a temperature dependent compensation portion. The temperature dependent compensation portion includes a temperature dependent component that is coupled to at least part of the sensing 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 a ratio of a first current to a second current to increase in the sensing coil configuration, wherein the first and second currents are in at least one first sensing coil and at least one second sensing coil, respectively, of the sensing coil configuration. Such implementations are configured to increase accuracy of the processed signals by at least partially compensating for certain affects that occur due to temperature changes.