Magnetostrictive Torque Sensor Crosstalk Compensation

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Solution Overview

Problem

Existing torque sensor arrangements for multiple shafts in close proximity suffer from measurement inaccuracies due to crosstalk caused by interfering magnetic fields, leading to falsified results.

Innovation Solution

A torque sensor arrangement that includes a compensation element, such as a compensation magnetic field sensor, positioned to equalize the interfering magnetic field at the measurement location, with additional developments involving maximizing distance and specific geometric arrangements of magnetized areas and sensors, including the use of measuring and compensation coils to perform differential measurements and compensate for interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple torque sensors are positioned close to each other to measure torque on adjacent shafts, then measurement coverage is improved, but measurement precision deteriorates due to crosstalk from interfering magnetic fields

Engineering Contradiction:
Improvemeasurement coverageVSAvoidmeasurement accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

A compensation element (compensation coil or compensation magnetic field sensor) is introduced as an intermediary between the interfering magnetized area and the affected magnetic field sensor. This compensation element generates a counteracting magnetic field that neutralizes the interfering magnetic field from adjacent shafts, allowing multiple sensors to operate closely together without crosstalk affecting measurement accuracy

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The compensation element is positioned and configured in advance to generate a magnetic field that opposes and cancels out the interfering magnetic field before it can distort the measurement. By pre-positioning the compensation element where the interfering field magnitude equals the compensation field magnitude, the system proactively neutralizes crosstalk effects

Inventive Principle:
Principle #9Preliminary anti-action

2Reliability

If the compensation element is positioned close to the magnetized area to effectively compensate for interference, then compensation effectiveness is improved, but device complexity increases due to precise positioning requirements

Engineering Contradiction:
Improvecompensation effectivenessVSAvoidpositioning complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The compensation element is positioned asymmetrically relative to the magnetized area, specifically at a location where the interfering magnetic field magnitude equals the compensation field magnitude. This asymmetric positioning optimizes compensation effectiveness while maintaining a practical, non-symmetric arrangement that simplifies implementation

Inventive Principle:
Principle #4Asymmetry

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 solution effectively compensates for interfering magnetic fields, enhancing measurement accuracy and allowing for precise torque detection in adjacent shaft configurations.

Implementation Method 1

a first magnetic field sensor (30) for measuring a magnetic field generated by the first magnetized area (20)

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

a second magnetic field sensor (31) for measuring a magnetic field generated by the second magnetized area (21)

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 3

a first compensation element (40) for at least partial compensation of an interference influence of the second magnetized area (21) of the second shaft (11) on the torque measurement of the first torque sensor (20, 30)

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 4

detect magnetic field changes that occur under load due to the magnetoelastic effect (inverse magnetostriction)

Methodology Applied
Scientific EffectMagnetoelastic effect (inverse magnetostriction): Magnetoelastic Effects

Data Source

PatentEP3495792B1Device and method for compensating for external fields in magnetostrictive torque measurement
Publication Date: 2021.02.03 NCTE
  • EP3495792B1 patent drawingFigure 1A~1B
  • EP3495792B1 patent drawingFigure 2

AI summary

The torque sensor arrangement according to the invention for detecting the torque on at least two shafts in a shaft arrangement comprises a first and a second shaft of the shaft arrangement, wherein the first and the second shaft are preferably arranged parallel to each other; a first magnetoelastic torque sensor for measuring the torque on the first shaft, wherein the first torque sensor comprises a first magnetized region of the first shaft and a first magnetic field sensor for measuring a magnetic field generated by the first magnetized region; a second magnetoelastic torque sensor for measuring the torque on the second shaft, wherein the second torque sensor comprises a second magnetized region of the second shaft and a second magnetic field sensor for measuring a magnetic field generated by the second magnetized region;and a first compensation element for at least partially compensating for an interference influence of the second magnetized area of ​​the second shaft on the torque measurement of the first torque sensor. Furthermore, a corresponding method is disclosed.