Control of an unmanned aerial vehicle (UAV)
requires knowledge of information on its attitude, which is
estimated with the help of satellite receivers, gyros,
accelerometers, and magnetometers. To ensure correct
measurements, all sensors are to be calibrated before the flight.
However, the ground-based calibration of the magnetometer
cannot ensure correct measurements of Earth's magnetic field
because of the additional magnetic fields created by strong
currents arising in the electric motor circuits in the course of
flight. The paper addresses the problem of fine compass
calibration to determine in-flight calibration parameters. Two
calibration techniques are proposed and discussed. The
discussion is illustrated by results of field experiments with an
octocopter Triumph-F1.