  We present a method to autonomously land an Unmanned Aerial Vehicle on a
moving vehicle with a circular (or elliptical) pattern on the top. A visual
servoing controller approaches the ground vehicle using velocity commands
calculated directly in image space. The control laws generate velocity commands
in all three dimensions, eliminating the need for a separate height controller.
The method has shown the ability to approach and land on the moving deck in
simulation, indoor and outdoor environments, and compared to the other
available methods, it has provided the fastest landing approach. It does not
rely on additional external setup, such as RTK, motion capture system, ground
station, offboard processing, or communication with the vehicle, and it
requires only a minimal set of hardware and localization sensors. The videos
and source codes can be accessed from http://theairlab.org/landing-on-vehicle.
