Capacitive Torque Sensor Flexure Hinge Design
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Solution Overview
Problem
Existing torque sensors, particularly those using strain gauges, face challenges in mass production due to high production costs, vulnerability to external impacts, and complexity in isolating torque measurements from non-reference axis directions, limiting their application in fields like robotics.
Innovation Solution
A capacitive torque sensor design featuring a sensing plate with angularly arranged grooves and electrodes, and a ground plate with protruding bars, allowing for relative movement and capacitance variation analysis to isolate torque measurements in a single axis direction without the need for complex mechanisms, enabling miniaturization and simplified calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauge based torque sensors are used, then torque measurement capability is achieved, but production cost increases and mass production becomes difficult
Solution Approach 1:
The patent replaces the strain gauge based mechanical sensing system with a capacitive sensing system. The torque sensor uses capacitive elements that detect torque through capacitance changes, eliminating the need for strain gauge bonding operations and enabling automated mass production while maintaining measurement precision.
Solution Approach 2:
The patent changes the sensing parameter from resistance (strain gauge) to capacitance (capacitive elements). This parameter change enables automated manufacturing processes and reduces production costs while preserving the ability to accurately measure torque through the capacitive response to applied torque.
2Measurement precision
If strain gauge based torque sensors are used, then torque measurement is possible, but vulnerability to external impacts increases
Solution Approach 1:
The patent replaces the fragile strain gauge bonding structure with a robust capacitive sensing structure. The capacitive elements are integrated into the sensor body without requiring external bonding, making the sensor more resistant to external impacts and environmental conditions while maintaining torque measurement accuracy.
3Measurement precision
If mechanisms are added to remove interferences from axial directions, then torque measurement accuracy in reference axis direction is improved, but device complexity increases
Solution Approach 1:
The patent uses asymmetric arrangement of capacitive elements around the sensing axis. This asymmetric configuration creates inherent directional sensitivity that naturally rejects interference from axial directions perpendicular to the reference axis, eliminating the need for additional complex mechanisms or algorithms while maintaining measurement accuracy.
Solution Approach 2:
The patent assigns different functional roles to different capacitive elements based on their local positions. Each capacitive element is optimized for its specific orientation, with the arrangement and configuration of elements at each location tailored to detect torque while rejecting interference from specific axial directions, achieving high measurement accuracy without additional 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 capacitive torque sensor effectively isolates torque measurements in the reference axis direction, decouples influences from other directions, and allows for miniaturization without the need for complex mechanisms, reducing production costs and enhancing robustness.
Implementation Method 1
a capacitive torque sensor including a sensing plate including four grooves formed at angular intervals of 90 degrees on the basis of a center point and four electrodes located at one-side of the four grooves, and a ground plate including four protrusion bars inserted into the four grooves of the sensing plate
Data Source
AI summary
Provided herein is a capacitive torque sensor, which can completely offset forces/torques in all axial directions, except for force/torque in a direction of a central axis, by measuring variations in capacitances of four sensing cells arrayed at angular intervals of 90 degrees on the basis of a center of the sensor and can offer a sensing value for the torque in a central axis direction.