Switching Six-Axis Force-Torque Sensor Eliminates Wheatstone Bridge Wiring
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Solution Overview
Problem
Conventional six-axis force-torque sensors face measurement errors due to complex wiring and high costs associated with Wheatstone bridge circuits, leading to inaccuracies and increased facility investment.
Innovation Solution
A switching type six-axis force-torque sensor configuration that eliminates the need for Wheatstone bridge circuits by using a silicon wafer substrate with radially disposed piezoresistive pattern portions and strain gauges, connected through resistance detecting units to sense strain signals in a switching manner, reducing the number of gauges and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a Wheatstone bridge circuit is used to measure six-axis force-torque, then measurement capability is achieved, but wiring complexity increases and measurement precision deteriorates due to errors
Solution Approach 1:
The patent extracts and eliminates the Wheatstone bridge circuit from the measurement system. Instead of using traditional strain gauges connected through complex Wheatstone bridge wiring, the invention directly integrates piezoresistive patterns onto the silicon wafer substrate, removing the need for external bridge circuits and reducing wiring complexity while improving measurement accuracy
Solution Approach 2:
The patent replaces the mechanical/electrical Wheatstone bridge circuit system with a semiconductor-based piezoresistive sensing system. By fabricating piezoresistive patterns directly on the silicon wafer, the invention substitutes complex external wiring with integrated semiconductor structures, thereby reducing device complexity and improving measurement precision
2Measurement precision
If strain gauges are attached to structural body to measure force and torque, then measurement function is achieved, but measurement precision deteriorates due to attachment errors
Solution Approach 1:
The patent merges the strain sensing function directly into the structural body by fabricating piezoresistive patterns onto the silicon wafer substrate. This integration eliminates the separate attachment step of strain gauges to the structural body, removing the source of attachment errors and improving measurement precision while simplifying the manufacturing process
Solution Approach 2:
The patent creates piezoresistive patterns that are fabricated copies of the structural body's deformation characteristics. By manufacturing these patterns directly on the silicon wafer using semiconductor processes, the invention captures the structural body's strain field without requiring physical attachment of separate sensing elements, thereby eliminating attachment errors
3Measurement precision
If multiple strain gauges are used to measure six-axis force-torque, then measurement capability is improved, but device complexity increases due to increased number of components
Solution Approach 1:
The patent makes each piezoresistive pattern on the silicon wafer multi-functional, where a single integrated sensing structure can detect multiple components of force and torque simultaneously. By strategically positioning and orienting piezoresistive patterns on the silicon wafer, the invention achieves six-axis measurement capability without requiring separate strain gauges for each axis, thereby reducing the total number of components while maintaining sensing performance
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 maximizes the resistance signal for measuring predetermined forces while minimizing unnecessary signals, enhancing sensing performance and reducing the complexity of the sensor setup, thereby improving measurement accuracy and cost-effectiveness.
Implementation Method 1
a method, which manufactures a piezoresistive pattern on a silicon surface through a semiconductor process, attaches the piezoresistive pattern to a structural body which generates deformation, and measures force and torque
Data Source
AI summary
A switching type six-axis force-torque sensor is provided which includes: a sensor substrate attached to a structural body to be measured. A first measuring unit is installed at one side in respect to a central portion of the sensor substrate and measures strain and a second measuring unit is installed on the sensor substrate at a position that faces the first measuring unit in respect to the central portion and measures strain. Further, a third measuring unit is installed at a position that is orthogonal to a connecting line, which connects the first measuring unit and the second measuring unit, and measures strain and a fourth measuring unit is installed at a position that faces the third measuring unit in respect to the central portion and measures strain.