Inductive Stylus Position Detection Crosstalk Reduction
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Solution Overview
Problem
Existing inductive sensing configurations for coordinate measuring machines (CMMs) face challenges such as inaccuracies, susceptibility to cross-coupling errors, signal non-linearities, and environmental influences, which affect the precision and reliability of measurements.
Innovation Solution
A scanning probe with a stylus position detection system utilizing a field generating coil configuration, including top and bottom axial sensing coils and rotary sensing coils, coupled with a disruptor element that moves within a disruptor motion volume, and signal processing circuitry to reduce crosstalk and enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LVDTs or known inductive type sensors are used to measure displacements in mechanical contact probes, then measurement accuracy is improved, but device size increases and cost increases
Solution Approach 1:
The sensing system is divided into multiple discrete coil assemblies arranged in a specific geometric pattern. Each coil assembly independently contributes to the overall measurement capability, allowing the system to achieve high-dimensional measurement accuracy without requiring a single large sensor. The segmentation of the magnetic field generation and detection functions across multiple smaller coil elements enables compact integration while maintaining measurement precision.
Solution Approach 2:
The invention transitions from traditional one-dimensional LVDT measurement to multi-dimensional position detection using a three-dimensional array of coil assemblies. By arranging coils in multiple spatial dimensions and utilizing the vector nature of magnetic fields, the system can determine position in three-dimensional space simultaneously, replacing multiple linear sensors with a more compact volumetric arrangement.
2Measurement precision
If LVDTs or known inductive type sensors are used to measure displacements in mechanical contact probes, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
Multiple measurement functions (axial position, radial position, angular orientation) are merged into a single integrated coil assembly system. The magnetic field interactions between the coils and the target provide coupled information about all spatial dimensions simultaneously, eliminating the need for separate sensing mechanisms for each degree of freedom and reducing overall system complexity.
Solution Approach 2:
The invention replaces complex mechanical displacement measurement mechanisms with an electromagnetic field-based sensing system. By using magnetic field induction and interaction between coil assemblies and a magnetic target, the system achieves precise position measurement without the mechanical linkages, gears, and contacts that would increase system complexity and reduce reliability.
3Device complexity
If traditional inductive sensing configurations are used, then device simplicity is maintained, but cross-coupling errors and signal non-linearities increase
Solution Approach 1:
The coil assemblies are arranged in an asymmetric three-dimensional configuration optimized to minimize cross-coupling between measurement axes. The specific spatial relationships and orientations of the coils are designed to create independent measurement channels that reduce interference between axial, radial, and angular measurements, thereby improving accuracy while maintaining reasonable system simplicity.
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 provides robust and accurate three-dimensional position measurements by minimizing cross-coupling errors and signal non-linearities, improving the precision and reliability of CMMs.
Implementation Method 1
A field generating coil configuration generates a changing magnetic flux (e.g., encompassing all or at least part of the disruptors)
Implementation Method 2
coil signals indicate the stylus positions
Data Source
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AI summary
An inductive position detection configuration for stylus position measurement in a scanning probe comprises a stylus position detection portion arranged along a central axis in the probe. The stylus position detection portion includes a field generating coil configuration and top and bottom axial and rotary sensing coil configurations. The field generating coil configuration generates a changing magnetic flux, and coil signals indicate conductive disruptor element and/or stylus positions. A field generating coil coupling and crosstalk reducing configuration couples signal processing and control circuitry to the field generating coil configuration to provide a coil drive signal, and is configured to reduce crosstalk that would otherwise occur if the field generating coil configuration were directly connected to the signal processing and control circuitry without the field generating coil coupling and crosstalk reducing configuration.