Magnetometer Attitude Fault Detection via Earth Magnetic Field Model
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing aircraft systems face challenges in detecting attitude faults, especially when redundant attitude systems disagree, and there is a need for a system that can accurately identify errors without additional hardware.
Innovation Solution
A magnetometer-based system that uses a three-axis magnetometer, attitude sources like ADIRU or AHRU, and an attitude monitor with a CPU or DSP to compare measured magnetic field estimates with Earth Magnetic Field Model estimates, projecting them into a common frame to detect attitude errors and output warnings if differences exceed thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant attitude systems are used for fault detection, then reliability is improved, but device complexity increases
Solution Approach 1:
The magnetometer is used for multiple purposes: its primary function of measuring magnetic field strength for heading determination is combined with a secondary function of detecting attitude faults by comparing measured values with expected values from a magnetic field model, eliminating the need for separate redundant attitude systems
Solution Approach 2:
The attitude monitoring system uses the existing magnetometer measurements and Earth Magnetic Field Model to self-diagnose attitude faults, without requiring external redundant attitude sensors or additional hardware components
2Device complexity
If magnetometer measurements are used for attitude fault detection, then device complexity is reduced, but measurement precision requirements increase
Solution Approach 1:
The Earth Magnetic Field Model acts as an intermediary reference, providing expected magnetic field values at different locations and times. The comparison between measured and modeled values enables fault detection while accounting for variations in the Earth's magnetic field due to position, time, and environmental factors
Solution Approach 2:
The system accounts for changes in magnetic field parameters (strength and direction) due to variations in geographic position, time, and local environmental factors by dynamically updating the Earth Magnetic Field Model expectations, allowing accurate fault detection despite these natural variations
3Reliability
If attitude faults are detected by comparing redundant systems, then reliability is improved, but difficulty of detecting and measuring increases when systems disagree
Solution Approach 1:
The system continuously compares magnetometer measurements with expected values from the Earth Magnetic Field Model, providing real-time feedback on attitude accuracy. When discrepancies exceed thresholds, the system generates alerts, enabling continuous monitoring and immediate identification of attitude faults without ambiguity
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 the detection of attitude faults without additional hardware, providing accurate warnings of errors in attitude solutions, thereby enhancing aircraft safety by identifying suspect attitude data and reducing ambiguity in redundant systems.
Implementation Method 1
a three-axis magnetometer, and a magnetic field measurement from the magnetometer
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An avionics system comprises one or more attitude sources, each configured to produce a respective calculated attitude solution; at least one magnetometer configured to measure magnetic field; and at least one attitude monitor configured to use the respective calculated attitude solution from one of the attitude sources to project the measured magnetic field estimate or an Earth Magnetic Field Model (EMFM) estimate such that the measured magnetic field estimate and the EMFM estimate are in a common shared frame. The at least one attitude monitor is further configured to determine a difference between the measured magnetic field estimate and the EMFM estimate in the common shared frame. The at least one attitude monitor is further configured to output an alert, which indicates that the respective calculated attitude solution used to project the measured magnetic field estimate or the EMFM estimate is in error, if the difference exceeds a predetermined threshold.