Magnetic interference mapping of four types of unmanned aircraft systems intended for aeromagnetic surveying

Abstract

Abstract. Magnetic interference source identification is a critical preparation step for magnetometer-mounted unmanned aircraft systems (UAS) used for high-sensitivity geomagnetic surveying. A magnetic field scanner was built for mapping the low-frequency interference that is produced by a UAS. It was used to compare four types of electric-powered UAS capable of carrying an alkali-vapour magnetometer: (1) a single-motor fixed-wing, (2) a single-rotor helicopter, (3) a quad-rotor helicopter, and (4) a hexa-rotor helicopter. The scanner's error was estimated by calculating the root-mean-square deviation of the background total magnetic intensity over the mapping duration; averaged values ranged between 3.1 and 7.4 nT. Each mapping was performed above the UAS with the motor(s) engaged and with the UAS facing in two orthogonal directions; peak interference intensities ranged between 21.4 and 574.2 nT. For each system, the interference is a combination of both ferromagnetic and electrical current sources. Major sources of interference were identified such as servo(s) and the cables carrying direct current between the motor battery and the electronic speed controller. Magnetic intensity profiles were measured at various motor current draws for each UAS, and a change in intensity was observed for currents as low as 1 A.

Unmanned Aerial Vehicles for Magnetic Surveys: A Review on Platform Selection and Interference Suppression

“…Tuck et al [111] built a magnetic field scanner for mapping the interference produced by four types of electric-powered UAV, i.e., a fixed-wing, an unmanned helicopter, a quadrotor, and a six-rotor UAV. The scanner was constructed of low susceptibility materials and moved along an aluminum track above the UAV, two magnetometers were used to record magnetic data.…”

“…A common practice is to install the magnetometer at the wingtips or nose tip, where the magnetic interference is usually small. Compensation flight is usually necessary for fixed-wing UAVs, and the traditional compensation flight method can be applied after slight modification since the aerodynamic structure of fixed-wing UAVs is similar to that of traditional manned aircraft [111,122].…”

“…The magnetic signature of unmanned helicopters is usually presented as a quadrupole or a dipole, where the servos and the engine provide the main contribution to the interference [108,111]. A simple method to mitigate the interference is by suspending the magnetometer below the UAV by a rope (usually over 3 m) or rigidly attached to the UAV frame by means of a rod, compensation is still effective as demonstrated in [79,125].…”

Two-Stage Calibration Scheme for Magnetic Measurement System on Guided Munition

“…According to the theory about electromagnetic field, the influence of the eddy current magnetic field on the projectile magnetic sensor can be described as: The changes in the projectile are mainly caused by the steering gear, the rudder blades and the attitude adjustment engine, etc. [32]. For the convenience of analysis, the eddy current magnetic field of the projectile can be described as a three-dimensional random vector, that is:…”

Research on aeromagnetic data error analysis and processing of multi-rotor UAV based on variational mode decomposition algorithm

“…For safety reasons, the aeromagnetic system sensor of multi-rotor UAV is close to the fuselage, resulting in large noises such as interference from airborne electromagnetic equipment. In addition, the measurement data also contains interference from external environment, which requires data de-noising pretreatment ( Qiao et al., 2020 ; Li et al., 2018a , Li et al., 2018b ; Wood et al., 2016 ; Tuck et al., 2019 , 2021 ).…”