Integration of an Aeromagnetic Measurement System Based on an Unmanned Aerial Vehicle Platform and Its Application in the Exploration of the Ma’anshan Magnetite Deposit

Abstract

An unmanned aerial vehicle (UAV) aeromagnetic measurement system can precisely obtain large-scale data with high efficiency and low cost in regions with complex exploration conditions, which has aroused interest in the field of aerial survey. In this paper, based on the unmanned helicopter platform, an aeronautical magnetic field measurement system is integrated to complete the integration of a rotor UAV, magnetometers, and data recorders. Equipped with a three-axis fluxgate magnetometer for real-time flight compensation, the compensation deviation is ±0.052 nT, which meets the aeromagnetic survey specifications. The UAV can fly autonomously with a maximum load of 45 kg at a speed of 60 km/h for 2 h, and the wind resistance level is level 7. The system has completed a field test of 111.9 km in the Ma'anshan crisis mine region of China and collected 145,495 data points. Then, the adaptive down-sampling method is used to compress the data (to 1.7% of the original data), and it is applied to the three-dimensional magnetic inversion, which successfully obtains the spatial distribution characteristics of the underground orebody, improving the inversion efficiency while ensuring the target area resolution. Six favorable magnetite prospecting sites are delineated in the survey area through inversion results, which demonstrates the potential of the developed UAV aeromagnetic system in the exploration over the areas with complex terrain.

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

“…Jiang et al [79] integrated a helicopter UAV magnetic survey system which consisted of a helicopter, a high-precision potassium OPM, a fluxgate magnetometer, and a data recorder to obtain large-scale data with high efficiency in regions with complex conditions. The deviation, after compensation, is ±0.052 nT, which meets the high-resolution aeromagnetic survey specifications proposed by the Geological Survey of the Ministry of Natural Resources of China [80].…”

“…For fixed-wing UAVs and unmanned helicopters, post-compensation is usually necessary in addition to keeping the magnetic sensors as far away from the drones as possible. As declared in [79], an equation with 18 terms is established by linking UAV interference with maneuver to calculate the compensation coefficients:…”

“…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]. Machine learning algorithms such as neural networks can also be used to improve the effect of compensation, as declared in [126].…”

3D Convolution Conjugate Gradient Inversion of Potential Fields in Acoculco Geothermal Prospect, Mexico

“…Their continued use has resulted in a historical improvement on data acquisition and interpretation methodologies as well as in the development of surveying instruments. One example is the development of modern airborne gravity gradiometers (Zhdanov et al, 2004;Nabighian et al, 2005;Dransfield and Zeng, 2009;Jekeli, 2006) and the increased use of unmanned aerial vehicles for aeromagnetic surveys (e.g., Aleshin et al, 2020;Jiang et al, 2020;Parshin et al, 2020;Walter et al, 2020). These technological developments have yielded the assimilation of the larger potential field data sets needed to achieve higher subsurface detail for reservoir, mineral, and archaeological studies.…”

Application of a Drone Magnetometer System to Military Mine Detection in the Demilitarized Zone

“…Research is underway to achieve this goal, but no reliable method has yet been described [ 37 ]. Processing of data obtained using UAVs follows existing procedures used for manned and airborne magnetism observations [ 40 ]. Traditional methods require multiple steps and complex data processing.…”