Heading Reference System Soft Iron Magnetic Disturbance Compensation
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Solution Overview
Problem
Magnetic heading reference systems, such as those used in aircraft, are affected by local soft iron disturbances, leading to errors in magnetic heading determinations, and existing solutions are not cost-effective or efficient in compensating for these errors.
Innovation Solution
A system and method that periodically corrects for soft iron magnetic disturbances by comparing magnetometer readings with gyro measurements, using a predetermined threshold to adjust the heading signal, and employing a Kalman filter to blend gyro and magnetometer data, thereby maintaining accurate magnetic heading calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external magnetometers are located away from electrical devices to avoid soft iron magnetic disturbances, then measurement accuracy is improved, but installation cost and device complexity increase
Solution Approach 1:
The patent converts the harmful soft iron magnetic disturbances into a compensable error source. By using multiple magnetometers at different locations, the system captures the spatial variation of magnetic disturbances and uses computational algorithms to calculate and remove the distortion effects, thereby converting the harmful local magnetic fields into correctable measurement errors.
Solution Approach 2:
The patent introduces computational algorithms as an intermediary between the magnetometer measurements and the final heading calculation. These algorithms process the raw magnetic field data, identify soft iron distortion patterns, and apply corrections to produce accurate heading information, thereby mediating between the disturbed measurements and the required accurate output.
2Reliability
If multiple reference systems are installed at different locations to provide redundancy and alleviate soft iron effects, then measurement reliability is improved, but installation and maintenance cost increase
Solution Approach 1:
The patent merges multiple magnetometer measurements from different locations into a single corrected heading output. By combining the data from multiple sensors and processing them through a unified computational algorithm, the system achieves the reliability benefits of multiple reference systems while avoiding the need for multiple independent heading reference systems.
Solution Approach 2:
The patent creates a universal correction algorithm that can handle soft iron disturbances regardless of their specific location or configuration. This multi-functional approach allows the same computational method to correct errors from various sources and configurations, making the system adaptable to different installation scenarios without requiring specialized solutions for each case.
3Measurement precision
If multiple reference systems operate independently with error disabling, then measurement accuracy is maintained, but system complexity and loss of information increase
Solution Approach 1:
The patent implements a feedback mechanism where the computational algorithm continuously monitors measurements from multiple magnetometers, compares them against expected patterns, and dynamically adjusts the correction applied to each sensor's data. This feedback loop ensures that accurate information from all units is utilized while compensating for errors, rather than simply disabling units when errors are detected.
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
The solution effectively compensates for soft iron effects, improving the accuracy and reliability of magnetic heading determinations in various vehicles and navigation systems, reducing the need for costly multiple reference systems and minimizing installation and maintenance costs.
Implementation Method 1
the heading gyro is periodically corrected by means of data from an external magnetometer that relies on the earth's magnetic field to provide a heading relative to magnetic north
Implementation Method 2
the heading gyro is periodically corrected
Data Source
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AI summary
A method and system for compensating for soft iron magnetic disturbances in multiple heading reference systems, such as aircraft heading reference systems, integrated standby units; or vehicle inertial systems, detects and provides a heading correction signal to the error prone heading reference system when a detected difference in value between a gyro heading relative to magnetic north and a magnetometer reading during a defined measurement period exceeds a predetermined acceptable threshold value of change, such as one based on the expected gyro drift over that period. Upon receipt of the heading correction signal, the gyro heading is adjusted to maintain an accurate heading relative to true magnetic north. If this threshold value is not exceeded, then the magnetometer reading is used for the heading value. This method is periodically repeated in order to continually maintain an accurate heading and may be employed for each heading measurement axis.