The Issue of North: Determining Magnetic Heading Onboard a Drone

This paper discusses the challenge of accurately determining local magnetic North on airborne vehicles like drones. It focuses on Attitude and Heading Reference Systems (AHRS) that use Inertial Measurement Units (IMU) with Micro-Electro-Mechanic Sensors (MEMS) to measure angular velocities, acceleration, and the Earth’s magnetic field. The paper highlights the complexity of this task due to the Earth’s weak magnetic field and disturbances that can affect measurements. The discussion covers advanced estimation techniques, such as the Extended Kalman Filter (EKF) and the Unscented Kalman Filter (UKF), which are key methodologies for navigating the intricacies of nonlinear system dynamics. It also covers the impact of vibrations on measurement precision and categorizes vibration sources within UAVs. The paper concludes with an overview of the intricacies involved in determining magnetic North in UAVs and the sophisticated techniques employed to achieve high-precision orientation and navigation. Two numerical applications are also shown.