Autonomous Drone Landing with Fiducial Markers and a Gimbal-Mounted Camera for Active Tracking

Precision landing is a remaining challenge in autonomous drone flight. Fiducial markers provide a computationally cheap way for a drone to locate a landing pad and autonomously execute precision landings. However, most work in this field depends on either rigidly-mounted or downward-facing cameras which restrict the drone's ability to detect the marker. We present a method of autonomous landing that uses a gimbal-mounted camera to quickly search for the landing pad by simply spinning in place while tilting the camera up and down, and to continually aim the camera at the landing pad during approach and landing. This method demonstrates successful search, tracking, and landing with 4 of 5 tested fiducial systems on a physical drone with no human intervention. Per fiducial system, we present the distributions of the distances from the drone to the center of the landing pad after each successful landing. We also show representative examples of flight trajectories, marker tracking performance, and control outputs for each channel during the landing. Finally, we discuss qualitative strengths and weaknesses underlying each system.