Torque Sensor Bushing Isolates Torsion for Robot Arm Wrist
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Solution Overview
Problem
Designing a robot arm wrist that balances compactness, high torque capability, low backlash, and accurate torque measurement is challenging due to the need for a compact yet accurate torque sensor arrangement.
Innovation Solution
A torque sensor arrangement featuring a deflectable body with a strain gauge and a bushing that isolates torsion from the sleeve, allowing for precise torque measurement while maintaining compactness and reducing friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact torque sensor arrangement is used in the robot arm wrist, then the device size is reduced, but the accuracy of torque measurement may be compromised
Solution Approach 1:
The torque sensor is nested within the existing joint structure of the robot arm wrist. The deflectable body is positioned within the joint housing, and the interface member integrates with the drive shaft and housing structures. This nesting approach allows the torque sensor to occupy space that would otherwise be unused or structural, achieving compactness without sacrificing measurement accuracy.
Solution Approach 2:
The torque sensor design applies different material properties and structural characteristics to different parts of the sensor. The deflectable body uses materials with specific torsional rigidity and elasticity properties to ensure accurate torque measurement, while the interface member and housing integration provide structural support and compact packaging. This localized optimization of material and structural quality enables both compactness and accuracy.
2Force
If high torque capability is implemented in the joint, then the robot can handle heavier tools and deliver higher acceleration, but the joint size and complexity increase
Solution Approach 1:
The joint structure is designed to perform multiple functions: the drive shaft provides both mechanical drive transmission and serves as an interface for torque sensing. The housing integrates structural support, bearing accommodation, and torque sensor mounting. This multi-functionality reduces the number of separate components needed, achieving high torque capability without proportionally increasing complexity.
Solution Approach 2:
The joint is segmented into distinct functional modules: the drive shaft assembly, the bearing assembly, the torque sensor assembly, and the housing. This segmentation allows each component to be optimized independently for its specific function while maintaining overall compactness. The torque sensor is positioned as a separate module within the joint structure, allowing it to be designed for high torque measurement without affecting the mechanical drive components.
3Manufacturing precision
If conventional gear elements are used to minimize backlash, then positioning accuracy is improved, but maintenance requirements increase and worn particles are liberated
Solution Approach 1:
The patent replaces conventional mechanical gear elements with a direct drive configuration where the drive shaft rotates directly within the housing, eliminating gears entirely. This substitution eliminates backlash issues associated with gears while also eliminating the maintenance problems of worn gear particles. The torque sensor measures torque in this direct drive configuration, providing accurate measurements without the compromises required by conventional gear-based systems.
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 provides a compact, accurate, and low-backlash torque measurement system, enabling the robot arm to handle high torque loads with improved precision and reduced maintenance needs.
Implementation Method 1
a deflectable body attached at one end thereof to the interface member and comprising, at the other end of the deflectable body, an engagement configuration for rotationally engaging the second part
Implementation Method 2
a deflection sensor attached to the deflectable body
Implementation Method 3
the interface member defines a rigid sleeve extending around the deflectable body and the torque sensor arrangement further comprises a bushing located between and in contact with both the sleeve and the deflectable body
Data Source
AI summary
A torque sensor arrangement configured to attach between a first part and a second part to sense torque therebetween, the torque sensor arrangement comprising: an interface member having on its exterior an engagement configuration configured to rotationally engage the first part; a torsion member comprising a deflectable body attached at one end thereof to the interface member and comprising, at the other end of the deflectable body, an engagement configuration configured to rotationally engage the second part; and a deflection sensor attached to the deflectable body; wherein the interface member defines a rigid sleeve extending around the deflectable body and the torque sensor arrangement further comprises a bushing located between and in contact with both the sleeve and the deflectable body.