Influence of Drone Self-magnetic Noise on Airborne Magnetic Exploration

Drones are already being used in various applications. In geophysical exploration, drones are expected not only as a technology to realize low-cost aerial surveys replacing aircraft, but also as a technology to open up new applications by high-density data acquisition at low altitudes, easy access to difficult-areas to enter and more efficient exploration than land surveys. However, geophysical exploration using a drone has only just begun to be considered. In this study, the authors examined magnetic exploration using a drone. A drone itself becomes a magnetic noise source. For this reason, a technique for reducing magnetic noise due to drone is required. A drone body acts as a DC noise. Driving the motor to control the drone body generates fluctuating magnetic noise. In this study, the authors carried out magnetic exploration using MagArrow which is developed by Geometrics (USA) as a magnetometer for a drone. The measurement was performed by hanging MagArrow three meters below from the drone. As a result, the magnetic noise caused by the drone was large during hovering. Swaying MagArrow like a pendulum during the measurement hardly affected as magnetic noise. On the other hand, the change in the flying speed of the drone becomes the magnetic noise, because the changes in motor power consumption generate magnetic noise. So, it was found that the hanging length of three meters from the drone was not sufficient during hovering, and it is important to keep the velocity constant during magnetic measurement.