Rotary Shaft Torque Sensor Decoupling via Fixing Member Gap
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Solution Overview
Problem
Existing rotary shaft structures in robots face challenges in accurately detecting torque and maintaining wire longevity due to interference from reaction forces and limited rigidity, especially when using reduction gears with low reverse efficiency.
Innovation Solution
A rotary shaft structure comprising a first member, a second member rotatable about a rotation axis, an actuator with a torque sensor, and a fixing member that supports a wire body with a gap between the fixing member and the sensor, allowing precise torque detection and improved wire longevity by decoupling reaction forces from the torque sensor and enhancing structural rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the wiring member is supported by the output member disposed between the output shaft and the other link, then the wire body can be routed through the rotary shaft, but the reaction force from the wire body acts on the torque sensor causing inaccurate torque detection
Solution Approach 1:
The patent divides the support structure into separate components: the first fixing member is attached to the output shaft member, the second fixing member is attached to the rotary shaft, and the torque sensor is positioned separately. This segmentation isolates the reaction force path from the torque sensor, allowing accurate torque detection while maintaining wire routing functionality.
Solution Approach 2:
The patent introduces intermediate fixing members (first and second fixing members) that act as mediators between the wire body and the rotating components. These fixing members transmit the wire body's reaction forces to the output shaft member and rotary shaft respectively, preventing these forces from directly affecting the torque sensor while maintaining the wire routing function.
2Device complexity
If the reduction gear has low reverse efficiency, then the structure is simpler, but the reaction force from the wire body cannot be properly separated causing interference with torque detection
Solution Approach 1:
The patent extracts the reaction force transmission path from the torque sensor system by using separate fixing members. The first fixing member transmits reaction forces to the output shaft member, while the torque sensor independently measures torque without being affected by these reaction forces, effectively separating the two functional paths.
3Device complexity
If the wire body is fixed directly to the rotary shaft, then the structure is simpler, but the wire body experiences increased deformation and tension reducing its lifespan
Solution Approach 1:
The patent segments the fixing structure into distributed fixing members along the rotary shaft rather than a single direct fixation point. This distribution reduces localized stress concentration and deformation on the wire body, extending its service life while maintaining the necessary structural support.
Data Source
AI summary
A rotary shaft structure including: a first member; a second member that is supported so as to be rotatable about a rotation axis with respect to the first member; an actuator that includes an output shaft member connected to the second member and that rotationally drives the second member about the rotation axis with respect to the first member; a sensor that detects a physical quantity acting between the output shaft member and the second member; and a first fixing member that is fixed to the output shaft member. A wire body is routed from the first member side to the second member side; the first fixing member extends toward the second member, with a prescribed gap between the first fixing member and the sensor; and the wire body routed from the first member side is fixed to the first fixing member on the second member side.