Optically-Guided Multirotor Autonomous Descent and Landing on a Moving Target

Abstract

We demonstrate the use of the AprilTag visual fiducial system for the precision landing of a multirotor vehicle on a moving target with no GPS use after target acquisition. Existing IR-LOCK precision landing code in a PixHawk flight controller with ArduCopter firmware is repurposed for passive ground target tracking using position information from a Raspberry Pi and PiCam, configured to identify and track a paper AprilTag. Debugging telemetry during development was exported by MAVLINK over 802.11ac Wi-Fi. The Apriltag removes the need for an active, IR- or RF-emitting ground beacon, allowing for precise aid delivery to unpowered disaster sites without necessitating human multicopter pilots be nearby for short-range work, nor cluttering longer-range cellular and radio bands. AprilTags allow for a sufficiently low false-positive rate to be used in debris-strewn environments and sufficient positional accuracy to land on small dinghies in flood zones or in the bed of an aid pickup truck.