Adaptive Magnetometer Calibration for UAV Orientation
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Solution Overview
Problem
Existing magnetometer compass calibration methods are ineffective in areas with large magnetic inclination, leading to inaccurate orientation determination of unmanned aerial vehicles (UAVs) due to insufficient change in the magnetic field direction when rotated horizontally.
Innovation Solution
An adaptive calibration procedure that determines the magnetic inclination using a global navigation satellite system (GNSS) and a global magnetic field model, performing different calibration sequences based on the inclination, including horizontal and vertical rotations to obtain accurate calibration values for the magnetometer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If horizontal rotation calibration is used, then calibration accuracy is improved in areas with small magnetic inclination, but calibration accuracy deteriorates in areas with large magnetic inclination
Solution Approach 1:
The calibration system dynamically adapts the rotation axis based on the local magnetic inclination angle. When the inclination angle exceeds a threshold, the system switches from horizontal rotation to vertical rotation, making the calibration process dynamic and adaptable to different geographic locations rather than using a fixed calibration method
Solution Approach 2:
The system changes the calibration parameter (rotation axis) based on the magnetic inclination angle. By detecting the inclination angle and switching between horizontal and vertical rotation modes, the system adjusts the calibration approach to match local magnetic field conditions, thereby maintaining calibration accuracy across diverse locations
2Ease of operation
If a fixed calibration sequence is used, then the calibration process is simple, but the calibration accuracy deteriorates in areas with large magnetic inclination
Solution Approach 1:
The calibration sequence transitions from static to dynamic by automatically selecting the rotation axis based on real-time detection of magnetic inclination. This dynamic adaptation maintains operational simplicity for the user while significantly improving calibration accuracy in high-inclination regions through automated sequence adjustment
3Reliability
If horizontal rotation is performed, then the calibration works well where magnetic field has substantial horizontal component, but the calibration fails where magnetic field has large vertical component
Solution Approach 1:
The system transitions from two-dimensional horizontal rotation to three-dimensional calibration by introducing vertical rotation when needed. This dimensional change allows the calibration to effectively capture magnetic field characteristics in both horizontal and vertical components, expanding geographic coverage to include high-inclination regions
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
Ensures accurate calibration of the magnetometer compass in any location, regardless of magnetic inclination, maintaining its usability and convenience by adapting the calibration process to vertical magnetic fields, thereby improving orientation determination of UAVs.
Implementation Method 1
An autonomous or a remote controlled aerial vehicle may include a magnetometer compass that measures the earth's magnetic field, by which the orientation (e.g., the heading) of the aerial vehicle may be determined
Implementation Method 2
A calibration system for a magnetometer of a compass includes a global magnetic field model store that stores a model of the earth's magnetic field and a magnetic inclination determination module that determines a magnetic inclination based on a current location of the aerial vehicle and the stored global magnetic field model
Data Source
AI summary
Disclosed is a system and method for calibrating a magnetometer. The method comprises responsive to a determination that a magnetic inclination is less than a threshold, measuring first magnetic field data by detecting a magnetic field with the magnetometer through a first rotation path, measuring second magnetic field data by detecting the magnetic field with the magnetometer through a second rotation path, and determining calibration values for the magnetometer based on the measured first magnetic field data and the measured second magnetic field data.