Square Bar Force Sensor with Diagonal Strain Gauges

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Solution Overview

Problem

Existing force measuring bodies have complex and large structures, making them inefficient for three-dimensional force measurement.

Innovation Solution

A measuring body with four identical webs aligned in a square, connected at connecting surfaces, equipped with strain gauges for measuring forces in multiple directions, including +45° and -45° angles, allowing for a simplified structure that enables three-dimensional force measurement using a Wheatstone measuring bridge configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional measuring bodies with multiple sections and additional webs are used to measure forces in the longitudinal direction, then force measurement capability is improved, but device complexity and volume increase

Engineering Contradiction:
Improveforce measurement capabilityVSAvoidstructure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The four webs are designed to serve multiple functions: they provide structural connection between base parts while simultaneously serving as mounting locations for strain gauges to measure forces in multiple directions (longitudinal, lateral, and diagonal at ±45°). This eliminates the need for separate measurement sections.

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

Solution Approach 2:

The patent measures forces in three dimensions (longitudinal axis, lateral direction, and diagonal directions at ±45°) using strain gauges arranged on the four webs. By utilizing the spatial arrangement of webs and gauge orientations, the system achieves multi-directional force measurement without adding longitudinal measurement sections.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If traditional measuring bodies with multiple sections are used to measure forces in the longitudinal direction, then force measurement capability is improved, but volume increases

Engineering Contradiction:
Improveforce measurement capabilityVSAvoidmeasuring body volume
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The four webs are designed to serve multiple functions: they provide structural connection between base parts while simultaneously serving as mounting locations for strain gauges to measure forces in multiple directions (longitudinal, lateral, and diagonal at ±45°). This eliminates the need for separate measurement sections.

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

3Ease of manufacture

If strain gauges are individually distributed on the webs without symmetrical arrangement, then manufacturing simplicity is maintained, but measurement precision decreases due to crosstalk

Engineering Contradiction:
Improvesensor arrangement simplicityVSAvoidforce measurement accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent employs symmetrical arrangement of strain gauges on the four webs, with specific orientation patterns (longitudinal, lateral, and diagonal at ±45°) that create a balanced measurement system. This symmetry minimizes crosstalk between different force measurement channels while maintaining manufacturing feasibility through standardized gauge placement patterns.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The Wheatstone bridge configuration provides built-in feedback and compensation for measurement errors. By arranging strain gauges in specific patterns and using bridge circuitry, the system automatically compensates for thermal effects, structural variations, and crosstalk, thereby improving measurement precision without complex individual sensor calibration.

Inventive Principle:
Principle #23Feedback

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 configuration allows for precise three-dimensional force measurement with minimal crosstalk and increased accuracy, reducing the complexity and volume of the measuring body while ensuring symmetrical conditions for signal evaluation.

Implementation Method 1

The measurement of forces using the deformation of measuring bodies is known in principle

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

force measuring sensors on each of the webs

Methodology Applied
Scientific EffectPiezoresistive Effect: Piezoresistive Effect

Data Source

PatentEP2549253B1Measuring body, force sensor and measuring assembly for measuring forces
Publication Date: 2017.08.09 MAGNA STEYR FAHRZEUGTECHNIK AG & CO KG
  • EP2549253B1 patent drawingFigure 1~2
  • EP2549253B1 patent drawingFigure 3~5
  • EP2549253B1 patent drawingFigure 6

AI summary

The body (1a) has two spaced-apart base parts (2a, 2b) including mounting surfaces for introduction of forces to be measured, where the base parts are aligned along a longitudinal axis (z) and arranged in square bars (A-D), and the base parts are connected to four identical sets of force sensors. The first set of force sensors (3A, 3B) measures force in the axis, and the second set of sensors measures force normal to the axis. The third set of sensors measures force at an angle of 45 degrees to the axis, and the fourth set of sensors measures force at an angle of minus 45 degrees to the axis. An independent claim is also included for a measuring arrang1ement for measuring forces.