Six-Dimensional Force Sensor With Twelve Elastic Beams

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Solution Overview

Problem

Existing six-dimensional force and torque sensors face challenges such as limited self-decoupling, low torque measurement range, and high structural requirements for strength and rigidity, leading to systematic errors and reduced reliability.

Innovation Solution

A novel six-dimensional force and torque sensor with a self-decoupling structure, utilizing twelve elastic beams with strain gauges forming full bridge circuits, and a central boss with a rectangular columnar structure, capable of measuring large torque, featuring high rigidity, natural frequency, and precision through tension-compression and bending deformations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal foil patch type six-dimensional sensor is used, then excellent stability and low environmental requirements are achieved, but the structure cannot realize self-decoupling and systematic error increases

Engineering Contradiction:
ImprovestabilityVSAvoidsystematic error
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The sensor structure is divided into multiple independent elastic beams (first elastic beams and second elastic beams) that are symmetrically arranged. Each beam group independently measures specific force or torque components, enabling self-decoupling of the measurement channels and eliminating systematic errors from cross-directional interference.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first and second elastic beams are arranged asymmetrically with respect to the central axis, with the first elastic beams positioned at specific angular intervals and the second elastic beams positioned differently. This asymmetric yet symmetric arrangement enables independent measurement of different force and torque components while maintaining structural balance.

Inventive Principle:
Principle #4Asymmetry

2Device complexity

If existing three-beam structure is used, then结构简单 (simple structure) is achieved, but self-decoupling cannot be realized

Engineering Contradiction:
Improvestructure simplicityVSAvoidself-decoupling capability
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The measurement structure is segmented into multiple elastic beams arranged symmetrically around the central axis. Each beam acts as an independent measurement element, and their combined output enables self-decoupling of force and torque components without requiring complex external decoupling mechanisms.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each elastic beam serves multiple functions: it provides structural support, acts as a force transmission element, and functions as a measurement element with integrated strain gauges. This multi-functionality achieves self-decoupling without significantly increasing overall structural complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Force

If torque measurement range is increased, then large torque measurement capability is achieved, but requirements on strength and rigidity of elastomer and connecting pin increase

Engineering Contradiction:
Improvetorque measurement rangeVSAvoidstrength and rigidity requirements
Core Design Contradiction:
ForceVSStrength

Solution Approach 1:

The torque measurement function is segmented across multiple elastic beams positioned at different angular locations. Each beam shares the torque measurement load, allowing the sensor to measure larger torques without requiring any single beam or connecting element to have excessively high strength and rigidity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Multiple elastic beams are combined in a symmetric arrangement to collectively measure torque. The combined measurement capability of all beams enables large torque measurement while distributing the mechanical stress requirements across multiple elements, reducing individual strength and rigidity demands.

Inventive Principle:
Principle #5Merging (Combining)

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 sensor achieves self-decoupling, high precision, and the ability to measure large torque (50 N·m) with improved structural strength and linearity, allowing for dynamic testing and customizable measuring ranges and sensitivities.

Implementation Method 1

a plurality of strain gauges distributed on the twelve elastic beams respectively forms a full bridge type detection circuit

Methodology Applied
Scientific EffectStrain gauge effect: Piezoresistive Effect

Data Source

PatentEP3454032B1Six-dimensional force and torque sensor
Publication Date: 2021.07.28 NANJING BIO INSPIRED INTELLIGENT TECH
  • EP3454032B1 patent drawingFigure 1
  • EP3454032B1 patent drawingFigure 2
  • EP3454032B1 patent drawingFigure 3

AI summary

A novel six-dimensional force and torque sensor includes a central boss, a cylindrical housing arranged outside the central boss, and twelve elastic beams for connecting the central boss with the cylindrical housing. The twelve elastic beams are respectively provided with strain gauges as needed, and a bottom of the central boss is provided with a mounting hole for mounting a signal processing module. The present invention has the characteristics of self-decoupling, high rigidity, high natural frequency, desirable linearity, ideal repeatability and perfect hysteresis, and ability to measure a large torque (50 N • m). In addition, the sensor can be designed to have different measuring ranges and sensitivities by changing the dimensions of each of the elastic beams.