Flux Coupling Sensor Offset Invariant Position Sensing

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Solution Overview

Problem

Inductive magnetic sensors are not offset invariant, leading to inaccurate position determination due to sensitivity to alternating magnetic stray fields and limited correction capabilities for target offsets, especially in compact designs where offsets can be significant relative to sensor size.

Innovation Solution

An apparatus with at least two sensor elements, one generating and one receiving a magnetic field, where the target's non-rotational invariant shape affects the magnetic flux coupling in a way that offsets have minimal effect on the measured signal, allowing for accurate position determination regardless of target displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inductive magnetic sensors are used for position sensing, then the sensors are not affected by static disturbing magnetic fields, but they are sensitive to alternating disturbing magnetic fields and target offsets leading to inaccurate position determination

Engineering Contradiction:

Improveimmunity to static magnetic fieldsVSAvoidposition determination accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The sensor system is divided into multiple sensor elements (at least two) that are arranged in a specific geometric configuration. Each sensor element independently measures magnetic field properties, and the combined evaluation of these measurements enables offset-invariant position determination while maintaining immunity to static magnetic fields.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sensor elements are arranged in an asymmetric geometric configuration relative to the target object. This asymmetric arrangement creates measurement patterns that are sensitive to position but invariant to offsets, allowing the system to distinguish between actual position changes and offset errors.

Inventive Principle:

Principle #4Asymmetry

2Area of stationary object

If the sensor size is reduced for compact integration, then the packaging area is minimized, but the target offsets become significant relative to sensor size leading to incorrect position determinations

Engineering Contradiction:

Improvesensor packaging areaVSAvoidposition determination accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The solution moves from considering only lateral offset corrections to incorporating the third dimension (depth/distance) in the sensor-target geometry. By arranging sensor elements at specific distances and angles from the target, the system creates a three-dimensional measurement configuration that is inherently invariant to lateral offsets, enabling accurate position sensing in compact packages.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Measurement precision

If complex correction algorithms are implemented to compensate for target offsets, then position accuracy is improved, but device complexity increases

Engineering Contradiction:

Improveposition determination accuracyVSAvoidcorrection algorithm complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex software correction algorithms with a geometrically optimized sensor configuration. The physical arrangement of sensor elements in specific spatial relationships to the target creates inherent offset-invariance in the measurements, eliminating the need for complex computational corrections and reducing overall system complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Enables accurate and robust position sensing that is invariant to target offsets, reducing the impact of alternating magnetic stray fields and eliminating the need for complex correction algorithms, even when the target is significantly offset from the expected position.

Implementation Method 1

at least one sensor element of the at least two sensor elements generates an alternating magnetic field

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the target affects a coupling of a magnetic flux of the magnetic field between the at least one transmitting sensor element and the at least one receiving sensor element

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Data Source

PatentUS11162817B2Flux coupling sensor and target

Publication Date: 2021.11.02 MELEXIS TECHNOLOGIES SA

AI summary

An apparatus is arranged for sensing a position of a target, in particular for offset invariant sensing of the position of the target is described, as well as the respective target and the method. The apparatus comprises at least two sensor elements. At least one sensor element of the at least two sensor elements generates a magnetic field. At least one other sensor element of the at least two sensor elements receives the magnetic field and outputs at least one signal associated with the received magnetic field. The target affects a coupling of a magnetic flux of the magnetic field between the at least one sensor element generating the magnetic field and the at least one other sensor element receiving the magnetic field and wherein the target is non-rotational invariant.