In recent years, many so called "robotic toys" appeared at the market. Though these devices are called toys and they are primarily intended for games, they provide a set of sensors and actuators that can be controlled from a computer.
Hence these robotic devices may serve as non-expensive research tools, in particular for developing advanced software for controlling them. This paper describes a controller for landing of an AR.Drone, a quadricopter marketed by Parrot Inc.
This controller is designed or fully autonomous landing to a given visual pattern and for hovering above the pattern. We will show how to collect input information for the controller and how to use it in a classical PID controller.