Magnetometer Compensation for Excavator Heading Accuracy

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Solution Overview

Problem

Magnetometer measurements in heavy machinery are prone to errors due to movable ferrous components, which cause significant heading deviations and incorrect position determinations, especially in equipment like excavators with complex mechanical linkages, and existing calibration methods are impractical for such complex setups.

Innovation Solution

A method and system that model movable equipment members as magnetic dipoles, calculate their relative positions, and adjust magnetometer readings to compensate for magnetic disturbances, using a magnetic dipole model and a processor to modify measurements and account for local magnetic disturbances caused by ferrous components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If magnetometer measurements are used in heavy machinery with movable ferrous components, then cost-effective heading determination is achieved, but measurement precision deteriorates due to magnetic disturbances from movable members

Engineering Contradiction:

Improvecost-effectivenessVSAvoidheading accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent segments the magnetic disturbance source into individual movable ferrous members (boom, stick, bucket) and models each as a separate magnetic dipole. This allows the total magnetic disturbance to be calculated as the sum of contributions from each member, enabling precise compensation while maintaining cost-effectiveness of the magnetometer system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter representation by modeling each ferrous member as a magnetic dipole with specific parameters (magnetic moment, position, orientation). This parametric model allows dynamic calculation of magnetic disturbances as members move, enabling real-time compensation without hardware changes.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If existing calibration methods (ellipse/ellipsoid fitting) are used, then device complexity is reduced, but measurement precision deteriorates for equipment with complex movable linkages

Engineering Contradiction:

Improvecalibration simplicityVSAvoidheading accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the complex magnetic disturbance into segments corresponding to each movable member. Instead of treating the entire machinery as a single complex disturbance source, each member (boom, stick, bucket) is modeled separately, making the overall system manageable and accurate.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces magnetic dipole models as intermediary representations between the physical ferrous members and the magnetometer measurements. These dipole models serve as mediators that translate physical member positions and orientations into calculated magnetic disturbances for compensation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If non-magnetic heading systems are used to overcome magnetometer disturbances, then measurement precision is improved, but cost-effectiveness deteriorates significantly

Engineering Contradiction:

Improveheading accuracyVSAvoidcommercial viability

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent converts the harmful magnetic disturbances from movable ferrous members into beneficial information by modeling them as magnetic dipoles. The same ferrous members that cause disturbances are used as the source of compensation data, allowing the magnetometer system to correct its own errors using information about its own disturbance sources.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system performs self-compensation by using knowledge of its own ferrous members' positions and magnetic properties to calculate and remove their own disturbances from the magnetometer readings. This self-service approach eliminates the need for expensive external non-magnetic heading systems.

Inventive Principle:

Principle #25Self-service

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

Significantly reduces magnetometer errors induced by movable members, providing accurate heading information with reduced error, making the system more commercially viable and cost-effective for heavy machinery applications.

Implementation Method 1

Magnetometers are used frequently in many applications to measure the strength and direction of the magnetic field of the Earth

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

These disturbances may be caused by magnets, ferrous metal objects, and/or electric currents

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Implementation Method 3

Soft iron errors arise due to the induced magnetism caused by an externally applied magnetic field

Methodology Applied

Scientific EffectInduced magnetism: Magnetism

Data Source

PatentUS10698042B2Magnetometer compensation

Publication Date: 2020.06.30 LEICA GEOSYSTEMS AG

AI summary

A system and method that compensates for local disturbances in magnetometer measurements for working equipment. For example, compensating for magnetometer disturbances caused by a stick, boom, and bucket of an excavator. The compensation is performed by generating or obtaining a magnetic model of movable members, determining the position of each of the movable members, calculating an estimated magnetic disturbance, and modifying the magnetometer measurement.