Force Sensor Frame Slits for Stress Bias Reduction
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Solution Overview
Problem
Existing force detection apparatuses in industrial robots face challenges in downsizing while maintaining external force detection accuracy, as the integration of convex portions and reduced screw fixation lead to biased stress distribution and increased output in unintended axes, compromising detection precision.
Innovation Solution
A force detection apparatus with a first member having a frame shape and slits or through holes between sensor devices, which reduces stress distribution bias and other axis output, allowing for effective downsizing and improved detection accuracy, and an adjustment mechanism to fine-tune the slit or hole size for optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the four convex portions are integrated to reduce size and weight, then the placement space and number of screws are reduced, but the rigidity increases causing biased stress distribution and larger other axis output
Solution Approach 1:
The patent applies local quality by creating non-uniform structural features (slits or through holes) in specific locations of the first member. These local modifications selectively reduce rigidity in directions that cause stress distribution bias, while maintaining overall structural integrity and downsizing benefits. The slits or holes are strategically positioned to alleviate stress concentration in certain areas without compromising the compact design.
2Device complexity
If the convex portions are integrated, then the number of screws is reduced, but the stress distribution in sensor devices becomes biased
Solution Approach 1:
The patent introduces local structural variations (slits or through holes) in the first member to create non-uniform stress distribution patterns that compensate for the bias caused by integration. These local features selectively reduce rigidity in specific directions, allowing stress to distribute more evenly across the sensor devices while maintaining the simplified integrated structure.
3Volume of moving object
If the structure is made more rigid through integration, then downsizing is achieved, but other axis output increases
Solution Approach 1:
The patent uses local structural modifications (slits or through holes) to selectively reduce rigidity in directions that generate other axis output. By creating these localized flexibility zones, the patent suppresses harmful outputs in unintended axes while preserving the compact integrated design and maintaining rigidity in directions needed for accurate force detection.
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 enables precise force detection with reduced bias and other axis output, enhancing the accuracy and efficiency of force detection in industrial robots, particularly in applications where external forces are applied off-center.
Implementation Method 1
a first sensor device provided between the first member and the second member and having a piezoelectric element that outputs a signal according to an external force, and a second sensor device provided between the first member and the third member and having a piezoelectric element that outputs a signal according to an external force
Data Source
AI summary
A force detection apparatus includes a first plate, a second plate, a first member projecting from the first plate toward the second plate, a second member projecting from the second plate toward the first plate, a third member projecting from the second plate toward the first plate, a first sensor device provided between the first member and the second member and having a piezoelectric element that outputs a signal according to an external force, and a second sensor device provided between the first member and the third member and having a piezoelectric element that outputs a signal according to an external force, wherein the first member has a first projection in contact with the first sensor device, a second projection in contact with the second sensor device, and a slit or a plurality of through holes between the first projection and the second projection.