Torque Sensor Using Magnetic Phase Difference Detection

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Solution Overview

Problem

Torque sensors used in collaborative robots are expensive due to the use of strain gauges, which poses a cost burden for their integration.

Innovation Solution

A phase difference torque sensor design that includes a sensor unit detecting rotational positions in annular areas at different distances from the rotation center, a resilient body between these areas, and a detection unit calculating torque based on the phase difference detected by the sensor unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If strain gauges are used in torque sensor manufacturing, then torque detection accuracy is improved, but manufacturing cost increases

Engineering Contradiction:

Improvetorque detection accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the traditional strain gauge-based mechanical measurement system with a magnetic field-based detection system. Specifically, it uses magnetic sensors to detect the position of magnetic poles on the rotor, converting mechanical torque measurement into magnetic field detection, thereby eliminating the need for expensive strain gauges while maintaining measurement capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a simplified copy of the torque detection function using magnetic sensors instead of strain gauges. By detecting the angular position of magnetic poles and calculating torque based on the phase difference between sensors at different radii, it reproduces the torque measurement capability without requiring the expensive strain gauge components

Inventive Principle:

Principle #26Copying

2Reliability

If torque sensors are mounted on collaborative robots, then safety in operation is improved, but cost burden increases

Engineering Contradiction:

Improvesafety in operationVSAvoidcost burden

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent employs a cost-effective detection system using magnetic sensors and resilient bodies instead of expensive strain gauge-based torque sensors. The simplified design using standard magnetic components and flexible elements reduces the overall cost while maintaining the safety function required for collaborative robot operation

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 achieves cost reduction while maintaining torque resolution, eliminating the need for strain gauges and thereby reducing manufacturing costs.

Implementation Method 1

a resilient body that is provided between the first area and the second area

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS12320721B2Torque sensor

Publication Date: 2025.06.03 SONY GROUP CORP

AI summary

A torque sensor (200) includes a sensor unit (222), a resilient body (213), and a detection unit (223). The sensor unit (222) detects, from an output unit that is a rotational body of an actuator, a rotational position in an annular first area positioned at a first distance from a rotation center, and a rotational position in an annular second area positioned at a second distance longer than the first distance from the rotation center. The resilient body (213) is provided between the first area and the second area. The detection unit (223) detects a torque applied to the output unit, on the basis of a result of the detection by the sensor unit (222).