Multi-Elastic Force Sensor Structure for Six-Axis Precision

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Solution Overview

Problem

Existing force sensors face challenges in achieving high sensor output and measurement accuracy due to difficulties in designing stoppers with high rigidity variations and small displacement amounts, leading to vulnerability to noise and low accuracy.

Innovation Solution

The elastic body is designed with multiple elastic portions and relay portions connected in six axial directions, along with strain sensors and stoppers, to enhance displacement and protect the sensor from external forces, ensuring equal displacement in all directions and high rigidity control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the rigidity of the elastic body and strain body is increased to protect from external force, then the sensor body becomes more robust, but the amount of displacement in six axial directions becomes very small, making it difficult to implement the stopper and reducing sensor output

Engineering Contradiction:

Improverobustness of sensor bodyVSAvoidsensor output

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

The elastic body is divided into multiple elastic portions (first elastic portions, second elastic portions) that can deform independently in different directions. This segmentation allows the sensor body to maintain high rigidity overall while enabling sufficient displacement in specific measurement directions, resolving the contradiction between robustness and sensor output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the elastic body are designed with different rigidity characteristics. The first elastic portions are configured to provide high rigidity for structural support, while the second elastic portions are designed to allow greater displacement for measurement, creating local quality variations that satisfy both robustness and measurement precision requirements.

Inventive Principle:

Principle #3Local quality

2Reliability

If the rigidity of the sensor body is increased to reduce vulnerability to noise and external disturbances, then measurement accuracy improves, but the displacement amount decreases, making it difficult to implement stoppers and reducing sensor output

Engineering Contradiction:

Improveresistance to external disturbanceVSAvoidsensor output

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The sensor body is segmented into first elastic portions for structural stability and second elastic portions for measurement displacement. This allows the system to maintain high reliability against external disturbances while preserving sufficient displacement for accurate measurement and stopper implementation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The elastic body exhibits dynamic rigidity characteristics, being rigid in directions where external disturbances occur but flexible in directions where measurement displacement is needed. This dynamic behavior allows simultaneous achievement of reliability and measurement precision.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If the rigidity of the sensor body is made uniform across all axial directions, then the stopper design becomes simpler, but the displacement characteristics become less optimized for specific measurement directions

Engineering Contradiction:

Improvestopper design complexityVSAvoiddisplacement optimization

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The elastic body is designed with local quality variations where first elastic portions provide uniform rigidity for simplified stopper design, while second elastic portions provide direction-specific rigidity optimization for enhanced measurement precision. This local differentiation resolves the contradiction between design simplicity and measurement optimization.

Inventive Principle:

Principle #3Local quality

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

This design allows for increased displacement and improved measurement accuracy, protecting the sensor from external disturbances while maintaining high precision and output voltage, even under overload conditions.

Implementation Method 1

an elastic body deformable along six axial directions, for example, three axial directions and along three circumferential directions around the three respective axial directions

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

Each of the strain sensors comprises a strain body and a plurality of strain gauge provided on the strain body

Methodology Applied

Scientific EffectStrain gauge effect: Piezoresistive Effect

Data Source

PatentUS12618725B2Elastic body including deformable portions and force sensor using the same

Publication Date: 2026.05.05 NIDEC COPAL ELECTRONICS CORPORATION

AI summary

A force sensor includes a first structure, a second structure, a plurality of third structures and a plurality of strain sensors. The first structure includes three or more first elastic portions deformable in six axial directions. The second structure includes three or more second elastic portions deformable in the six axial directions, and three or more relay portions connected to the second elastic portions, respectively, and deformable in the six axial directions. A plurality of third structures are provided respectively between each of the relay portions of the second structure and each of the first elastic portions of the first structure. The plurality of strain sensors are provided between the first structure and each of the relay portions.