Small Signal Magnetic Compensation Method for UAV-Borne Vector Magnetometer System

Abstract

Aeromagnetic surveys using UAVs (Unmanned Aerial Vehicle) have attracted extensive interest, and aeromagnetic compensation is indispensable to improve the quality of magnetic field. For the vector magnetic sensors fixed on the drone, existing compensation methods are based on that the magnitude of vector magnetic field is a constant, but in theory, even if the center position of the UAV remains unchanged during rotation, the magnitude of the measured vector magnetic field is time-varying, because the interference field generated by the drone is related to its attitude, resulting in residual error after compensation. This paper creates a novel small signal model (SSM) based on the measured results of the vector magnetometer, compensating the permanent and induced interference magnetic field generated by the drone. A high-pass filter is used to separate the UAV interference field from the outputs of a vector magnetic sensor, and compensation parameters are estimated by the least square method. Meanwhile, compensation flight is the UAV-borne vector magnetometer system flying multiple lines in a small area, no need to keep the center of the system fixed while performing rotation operations in the air. Field experiments have been conducted, and the root mean square error of the compensated magnetic field is less than 1 nT. In addition, the subsequent test flight and detection experiment were carried out, showing that the SSM compensation can improve the quality of magnetic field.