Magnetic Position Sensor Using Analytical Field Correction

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Solution Overview

Problem

Existing position measurement methods using magnetically operating sensors are complex and require significant equipment and computational resources, and they struggle with accurately determining positions in environments with magnetic field distortions, such as metallic surfaces.

Innovation Solution

A method that uses a simple, analytically describable magnetic field, such as that generated by a cylindrical magnet, to measure position coordinates (x, y, z) by detecting magnetic field components (Bx, By, Bz) and applying a quotient relation involving the magnetic permeability constant and dipole moment, allowing for rapid and cost-effective position determination. This method also accounts for magnetic field distortions by using a mirror-symmetrical magnetic field model to correct for surface effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complex magnetic field measurement methods are used, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improveposition measurement accuracyVSAvoidequipment and computational resources
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and utilizes only the essential magnetic field components (Bx, By, Bz) at a single location to determine position, eliminating the need for complex multi-point measurements or additional sensors. This selective extraction of necessary information reduces device complexity while maintaining measurement precision through the analytical relationship between the simplified magnet's field and position coordinates

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the magnetic field source to a simplified geometry (cylindrical or spherical magnet with specific dimensions) that produces an analytically describable field. This parameter change in magnet geometry transforms the magnetic field characteristics, enabling position calculation from a simple triple of field components without requiring complex measurement systems

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If simple magnetic field models are used, then device complexity is reduced, but reliability decreases in environments with magnetic field distortions

Engineering Contradiction:
Improvecomputational expenseVSAvoidposition determination accuracy in distorted fields
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent performs preliminary action by pre-calculating and storing the analytical relationship between magnetic field components and position coordinates for the simplified magnet geometry. This pre-established mathematical model allows rapid position determination through simple calculations, maintaining low device complexity while improving reliability by having a ready-to-use correction framework for distorted fields

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates a simplified analytical copy of the magnetic field behavior using idealized magnet geometries with known field equations. This mathematical copy replaces complex real-world field variations, enabling reliable position determination through computationally simple operations while maintaining accuracy through the proven analytical relationships

Inventive Principle:
Principle #26Copying

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 rapid position measurement with minimal equipment and computational expense, suitable for cost-sensitive applications like domestic appliances and safety-critical systems, while effectively handling magnetic field distortions.

Implementation Method 1

the magnet generates an analytically describable magnetic field

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

a sensor detecting the magnetic field strength of the magnet

Methodology Applied
Scientific EffectMagnetic field detection: Magnetic Field

Data Source

PatentUS9995598B2Method for measuring a position
Publication Date: 2018.06.12 MARQUARDT GMBH

AI summary

A method for measuring a position using a magnet and a sensor for detecting the magnetic field strength of the magnet. The magnet and/or the sensor interact with a movable element so that a relative movement between the sensor and the magnet can be effected. The position of the movable element in accordance with the coordinates in a system of coordinates can be ascertained on the basis of the magnetic field having a predetermined shape generated by the magnet and detected by the sensor. The sensor ascertains three linearly independent spatial direction components of the magnetic field strength of the magnetic field acting at the location of the sensor. Each coordinate along a coordinate axis of the system coordinates of the magnetic field is determined individually and unambiguously by the combination of the three linearly independent spatial direction components of the magnetic field strength detected by the sensor.