Strain Gauge Measurement Probe for Robust Force Detection
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Solution Overview
Problem
Existing touch trigger probes are either not robust enough to withstand adverse conditions such as knocks and vibrations or are not sensitive enough for precise force detection, and analogue probes are not suited for rugged use due to their sensitivity and mechanical nature.
Innovation Solution
A measurement probe with a strain sensitive structure featuring a bendable arm member with a thin rectangular cross-section and strain sensing elements mounted on opposing short edges, which processes differential signals to provide a combined output, eliminating the need for additional stylus support and enhancing both sensitivity and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If touch trigger probes use conventional electrical switch arrangements, then they are simpler and better suited for machine tool applications, but they have moving parts which can become worn or damaged and are not robust enough to withstand adverse conditions
Solution Approach 1:
The patent replaces the conventional mechanical electrical switch arrangement with a strain gauge-based sensing system. The strain gauge cell detects workpiece contact through deformation of a bendable member, eliminating moving parts and providing a more robust solution that withstands adverse conditions while maintaining operational simplicity.
2Reliability
If probes use strain gauges to improve robustness, then they can withstand adverse conditions, but they are not sensitive enough for precise force detection
Solution Approach 1:
The patent optimizes the bendable member's geometric parameters, specifically using a thin rectangular cross-section with defined thickness and width ratios. This parameter optimization enhances the strain gauge's sensitivity to force detection while maintaining the robustness provided by the strain gauge configuration, resolving the contradiction between sensitivity and robustness.
3Reliability
If additional stylus support is provided to increase robustness, then the probe can withstand knocks better, but the probe structure becomes less compact and more complex
Solution Approach 1:
The bendable member serves multiple functions simultaneously: it acts as a structural support element, a strain sensing element, and a protective component. By integrating these functions into a single component with optimized geometry, the patent achieves robustness without requiring additional stylus support structures, thereby maintaining compactness and reducing overall complexity.
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 achieves a balance between sensitivity and robustness, allowing for precise force detection and resistance to excessive forces, ensuring reliable operation in adverse conditions without compromising sensitivity.
Implementation Method 1
a pair of strain sensing elements mounted on opposing sides of said bendable arm member, so as to provide respective signals upon bending thereof
Data Source
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AI summary
A probe for position determining apparatus has a probe body (18) and a workpiece-contacting stylus (14). A strain sensitive structure (70) connects the probe body (18) and the stylus (14), and includes at least one bendable member (90) which is bendable relative to the axis when the stylus (14) contacts a workpiece (50). A pair of strain sensing elements (33) are mounted on opposing sides of said bendable member (90), so as to provide respective signals upon bending thereof. A circuit (92) receives said signals and processes them differentially to produce a combined output signal.