Force Sensor Strain Element Projections for Wiring
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Solution Overview
Problem
The existing six-axis force-torque sensors face difficulties in wiring operations due to densely arranged electrodes on long, narrow structures, and the attachment of thin-film resistors on deformable arm portions or flexures leads to accuracy loss when external forces are applied.
Innovation Solution
A strain element with projections extending from the deformable portions in directions intersecting their longitudinal axes, allowing for easier attachment of strain gauges and resistive elements, reducing the density of electrodes and minimizing deformation-induced resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are attached to long narrow structures such as arm portions and flexures, then the force-torque sensor can detect external forces, but the electrodes are arranged densely resulting in difficulty in wiring operations
Solution Approach 1:
The invention extends the arm portions and flexures in the longitudinal direction to create longer measurement paths for strain gauges, while simultaneously providing wider lateral surfaces for electrode attachment. This dimensional extension resolves the contradiction by allowing both effective strain measurement and easier wiring operations on the same structure.
2Ease of manufacture
If thin-film resistors are attached near strain gauges to balance bridge circuit resistance, then the bridge circuit can be balanced, but the resistors change properties upon deformation resulting in loss of accuracy
Solution Approach 1:
The invention extracts the balancing resistor from the deformable structure and places it on a separate non-deformable portion of the strain element. This separation allows the bridge circuit to be balanced while preventing the balancing resistor from undergoing deformation-induced resistance changes, thus maintaining measurement accuracy.
3Ease of manufacture
If elements that change properties upon deformation are attached to arm portions or flexures, then the bridge circuit can be balanced, but the elements change properties when external force is exerted resulting in loss of accuracy
Solution Approach 1:
The invention applies different functional qualities to different parts of the strain element: the arm portions and flexures are designed to deform for measurement, while the mounting portions for balancing resistors are designed to remain non-deformable. This local differentiation ensures that circuit-balancing elements do not undergo deformation-induced property changes, maintaining measurement reliability.
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
This configuration facilitates easier wiring and attachment of components while maintaining accuracy by minimizing deformation of the projections and preventing resistance changes, thus enhancing the reliability of the force-torque sensor.
Implementation Method 1
a strain gauge attached to the deformable portion
Data Source
AI summary
The present invention achieves a force sensor in which an electrode, element, and/or the like connected to a strain gauge can be suitably attached to a strain element. The force sensor includes: a strain element including an arm portion that is deformable under an external force; and a strain gauge attached to the arm portion. The strain element includes a projection that sticks out from the arm portion in a direction intersecting the longitudinal direction of the arm portion.