Magnetic Calibration Method Based on Magnetic Gradient Measurement

Abstract

Before aircraft heading measurement by using a tri-axial magnetic sensor or magnetic anomaly detection, magnetic interference calibration of the magnetic sensor is required. In order to avoid the degradation of calibration accuracy due to the short-time fluctuation of the geomagnetic field, an interference calibration method for magnetic sensors using magnetic gradient measurement is proposed based on the geomagnetic field gradient distribution characteristics in near-earth space. A 24-parameter interference model for magnetic interference of the magnetic gradient measurement system is established, and a multivariate nonlinear equations is constructed based on multiple arbitrary rotations of the ellipsoidal fitting method for a single sensor, then by the solution of the nonlinear system equations using a genetic algorithm with higher region search efficiency. The simulation results show that, compared with the traditional ellipsoidal fitting calibration method, this proposed method overcomes the influence of short-time fluctuations of the geomagnetic field, and improves the calibration accuracy of the magnetic gradient measurement system, whose differential magnetic gradient measurement error can be calibrated to [1.848 2 1.845 3 1.915 0]T nT. This study provides a reliable guarantee for the carrier interference compensation and high-precision measurement of the aero magnetic system.

Keywords

• |magnetic gradient measurement|magnetic interference calibration|genetic algorithm|tri-axial magnetic sensor|ellipsoidal fitting|azimuth measurement|aircraft