Strain Body Design for Six-Axis Force Sensor Accuracy
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Solution Overview
Problem
Current six-axis force sensors used in robot arms face challenges in downsizing and enhancing performance to accurately detect external forces and torques in X, Y, and Z directions, with limitations in detection accuracy and sensitivity due to the design of strain bodies.
Innovation Solution
A strain body design with a central portion and outer peripheral portions, featuring bridge circuits and full-bridge circuits, where the connecting portions have increased elasticity and strain sensors are strategically placed to enhance detection accuracy, and a manufacturing method using thin-film technology for high-density sensor placement, reducing temperature errors and external noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple strain sensors are used to improve detection accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent combines multiple strain sensors (first and second strain sensors) into a single integrated strain body structure. The strain body integrates multiple detection functions into one component, reducing the total number of separate sensors needed while maintaining detection accuracy for six-axis forces and torques.
Solution Approach 2:
The strain body serves multiple functions simultaneously: it detects forces and torques in multiple directions (X, Y, Z axes), provides structural support, and integrates temperature compensation features. This multi-functionality reduces the need for separate dedicated sensors for each measurement function.
2Measurement precision
If strain sensors are placed densely to improve detection sensitivity, then measurement precision improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent implements local quality by creating a strain increasing portion with a specific groove structure at predetermined locations on the strain body. This localized structural modification concentrates strain in specific areas where sensors are placed, enhancing detection sensitivity without requiring uniformly high manufacturing precision across the entire sensor array.
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 strain body design improves detection accuracy and sensitivity by allowing for precise measurement of six-axis forces and torques, reducing the need for multiple sensors and minimizing errors, while maintaining a compact configuration.
Implementation Method 1
deformation of a strain sensor (strain gauge) provided on the strain body is converted into an electric signal and detected
Implementation Method 2
an external force applied to a force receiving body serving as a movable unit is transmitted to a strain body, and deformation of a strain sensor
Data Source
Figure 1~2
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AI summary
A strain body (16A) according to the embodiments comprises a central portion (161), an outer peripheral portion (162) surrounding the central portion, connecting portions (163) connecting the central portion and the outer peripheral portion, and each comprising a first connecting portion (163a) adjacent to the outer peripheral portion and a second connecting portion (163b) adjacent to the central portion, strain sensors (S1 to S32) provided on main surfaces of the connecting portions, reference resistors (RS4 to RS30) provided on a main surface of the central portion, and constructing a bridge circuit (BF2, BF4, BF6, BF8) with the strain sensors, and a strain increasing portion (GR) configured to increase strain occurring at the first connecting portion more than strain occurring at the second connecting portion, on a back surface side opposed to the main surface of the first connecting portion.