Torque Sensor Structure With Convex Guides for Thin, Rigid Sensing
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Solution Overview
Problem
Conventional torque sensors for robots lack sufficient mechanical strength in non-detection directions, leading to potential damage when forces are applied outside the primary detection axis, and this weakness can compromise detection accuracy.
Innovation Solution
A torque detection device comprising a first and second portion linked by a connecting portion, where both portions have convex surfaces that project towards each other, allowing for relative displacement when torque is applied, enhancing mechanical rigidity and accuracy by distributing stress across multiple surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional torque sensor structure is used, then the detection accuracy for torque is achieved, but the mechanical strength in non-detection directions is insufficient, leading to potential damage
Solution Approach 1:
The torque sensor is divided into multiple functional segments: a first annular member, a second annular member, and multiple connecting portions with strain causing members. This segmentation allows each component to specialize in specific functions - the connecting portions handle torque transmission while the strain causing members detect deformation, and the annular members provide structural support in non-detection directions.
Solution Approach 2:
The patent introduces convex portions that extend in the axial direction (perpendicular to the torque detection plane), adding a third dimension to the structure. These convex portions with contact surfaces provide mechanical strength in non-detection directions without interfering with the torque detection function in the radial plane.
2Strength
If a guide mechanism such as a bearing is added to ensure mechanical strength, then the rigidity in non-detection directions is improved, but the sliding resistance is detected by the torque sensor, deteriorating detection accuracy
Solution Approach 1:
The patent extracts the guidance function from separate bearing components and integrates it directly into the annular members through convex portions with contact surfaces. This eliminates the need for external guide mechanisms that would introduce sliding resistance, while still providing the necessary mechanical support in non-detection directions.
Solution Approach 2:
The guidance function is merged with the structural support function by incorporating contact surfaces directly onto the convex portions of the annular members. This combination allows the same structural elements to provide both mechanical strength and guidance without requiring separate bearing components.
3Length of moving object
If the torque sensor is made thinner to fit limited space, then the space requirement is reduced, but the mechanical strength and rigidity are compromised
Solution Approach 1:
The patent compensates for reduced thickness by utilizing the axial dimension through convex portions that extend in the thickness direction. These convex portions with contact surfaces provide mechanical strength and guidance functions without increasing the overall radial footprint, allowing the sensor to remain thin while maintaining structural integrity.
Solution Approach 2:
The patent employs strain causing members with specific material properties that combine high elasticity for detection with sufficient strength for mechanical support. The use of Cr-N thin-film resistive members and elastic materials allows the structure to be thin while maintaining both detection capability and mechanical strength.
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 torque sensor with high detection accuracy and improved mechanical rigidity in non-detection directions, reducing the risk of damage and maintaining precision even when thickness is minimized.
Implementation Method 1
When torque is applied, the connecting portion deforms, and the first portion and the second portion are displaced relative to each other
Data Source
AI summary
A torque detection device includes a first portion, a second portion disposed inside the first portion, and a connecting portion configured to link the first portion and the second portion. The first portion includes a first convex portion that projects toward the second portion. The second portion includes a second convex portion that projects toward the first portion. An inner surface of the first portion and a surface of the first convex portion link to the connecting portion. An outer surface of the second portion and a surface of the second convex portion link to the connecting portion. When torque is applied, the connecting portion deforms, and the first portion and the second portion are displaced relative to each other.