Asymmetric Torque Sensor Stiffness for Robot Arm Accuracy
Solution Overview
Problem
Torque sensors in robot arms experience reduced detection accuracy due to asymmetrical displacement caused by bending moments and translation forces, which interfere with torque measurement.
Innovation Solution
A torque sensor design with a first structure, a second structure, and a third structure, where the stiffness of the second structure is higher near the sensor portions, reducing deformation and interference from non-torque forces, and using strain gauges to detect torque while suppressing signals from bending moments and translation forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the torque sensor uses a symmetric structure with strain gauges arranged symmetrically, then the sensor can detect torque effectively, but bending moments and translation forces cause asymmetrical displacement that interferes with torque measurement and reduces detection accuracy
Solution Approach 1:
The patent intentionally introduces asymmetry by providing a stiffness difference between the first and second structures. Specifically, the stiffness of the first structure is made higher than that of the second structure, creating an asymmetric stiffness distribution that compensates for the asymmetrical displacement caused by bending moments and translation forces, thereby improving torque detection accuracy
Solution Approach 2:
The patent applies different stiffness properties to different parts of the sensor structure. The first structure (supporting the detection unit) is designed with higher stiffness compared to the second structure, creating localized stiffness variation that helps suppress the influence of external forces on the strain gauges while maintaining torque sensitivity
2Measurement precision
If the stiffness of both structures is increased to suppress deformation from external forces, then interference from bending moments and translation forces is reduced, but the overall thickness and weight of the torque sensor increase
Solution Approach 1:
Instead of uniformly increasing the stiffness of both structures, the patent selectively increases the stiffness only of the first structure that directly supports the detection unit and strain gauges. This localized stiffness enhancement suppresses deformation at the critical measurement point without requiring a proportional increase in the stiffness (and thus weight) of the entire sensor assembly
Solution Approach 2:
The patent divides the support structures into distinct first and second structures with different stiffness characteristics. The first structure is designed with higher stiffness to protect the detection unit, while the second structure can be lighter. This segmentation allows differential stiffness optimization that reduces overall weight compared to a uniformly stiff design
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
Improves torque detection accuracy by suppressing deformation and resistance variations from non-torque forces, maintaining sensor performance without increasing overall thickness or weight.
Implementation Method 1
a plurality of strain gauges serving as sensor elements are arranged on the strain parts
Data Source
AI summary
A torque sensor which can improve detection accuracy is provided. The torque sensor includes a first structure, a second structure, a third structure provided between the first structure and the second structure and at least two sensor portions provided between the first structure and the second structure, and a stiffness of one of the first structure and the second structure, closer to the sensor portions is higher than that of the other one.