INERTIAL-AIDED IN-MOTION MAGNETOMETER CALIBRATION WITHOUT A HEADING REFERENCE

Date

2026-7-29

Author

Dündar, Osman Harun

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At tactical and MEMS (micro-electro-mechanical systems) grades the magnetometer is the only absolute heading reference available in GNSS-denied (Global Navigation Satellite System) navigation, but it serves this role only after calibration, since softiron, hard-iron, scale, non-orthogonality, and above all the sensor-to-body mounting misalignment displace the reported field direction beyond any heading budget. Recasting the calibration problem by the orientation information entering the observation equation, this work replaces the attitude-independent/attitude-dependent binary with a four-family taxonomy and proves, via formal observability theorems, that two intermediate regimes recover the misalignment without absolute heading. Their residual degrees of freedom differ in kind. Relative-attitude calibration is blind to a uniform scale that a scalar field-magnitude reference closes; gravity- referenced calibration identifies the full model wherever the platform’s tilt varies, losing a rotational degree only at constant tilt. Two estimators realize this distinction. MACRO (Magnetic Calibration via Relative Orientation) is a twelve-state extended Kalman filter that eliminates the unknown field through a conjugated relative-rotation residual and closes the scale gauge online from the gyroscope and reference magnitude. GRACE-MC (Gravity-Referenced Attitude-Constrained Estimation for Magnetometer Calibration) is a batch maximumlikelihood estimator that recovers all twelve parameters from roll and pitch wherever the motion makes them observable. On real fluxgate data against a navigationgrade reference both attain 1.1°–1.9° heading accuracy, matching full-attitude methods while remaining outside the heading loop, and establish that geometric fit and heading accuracy are orthogonal—an orientation-free method achieving a tighter calibration sphere yet with eight times higher heading error.

Subject Keywords

Magnetometer calibration, Gyroscope-aided calibration, Calibration without a heading reference, Observability analysis, GNSS-denied navigation

URI

https://hdl.handle.net/11511/120062

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Graduate School of Natural and Applied Sciences, Thesis