A Precision Drone Landing System using Visual and IR Fiducial Markers
  and a Multi-Payload Camera
Joshua Springer Gylfi Þór Guðmundsson Marcel Kyas
We propose a method for autonomous precision drone landing with fiducial
markers and a gimbal-mounted, multi-payload camera with wide-angle, zoom, and
IR sensors. The method has minimal data requirements; it depends primarily on
the direction from the drone to the landing pad, enabling it to switch
dynamically between the camera's different sensors and zoom factors, and
minimizing auxiliary sensor requirements. It eliminates the need for data such
as altitude above ground level, straight-line distance to the landing pad,
fiducial marker size, and 6 DoF marker pose (of which the orientation is
problematic). We leverage the zoom and wide-angle cameras, as well as visual
April Tag fiducial markers to conduct successful precision landings from much
longer distances than in previous work (168m horizontal distance, 102m
altitude). We use two types of April Tags in the IR spectrum - active and
passive - for precision landing both at daytime and nighttime, instead of
simple IR beacons used in most previous work. The active IR landing pad is
heated; the novel, passive one is unpowered, at ambient temperature, and
depends on its high reflectivity and an IR differential between the ground and
the sky. Finally, we propose a high-level control policy to manage initial
search for the landing pad and subsequent searches if it is lost - not
addressed in previous work. The method demonstrates successful landings with
the landing skids at least touching the landing pad, achieving an average error
of 0.19m. It also demonstrates successful recovery and landing when the landing
pad is temporarily obscured.