Optical Position Stabilization of an UAV for Autonomous Landing

Vertical Take-Off and Landing (VTOL) capable Mini Unmanned Aerial Vehicles (MUAV) are an economic alternative to real helicopters if local aerial pictures or other aerial measurements are needed. With electronic stabilization, GPS based position-hold and autonomous way-point functions these systems are easy to operate. While autonomous take off and flying are done routinely, this is not true for autonomous landing. GPS based position stabilization, in conjunction with the normally used cheap and small IMUs, is not accurate enough to avoid dangerous moves in the very last moment of the landing operation. While sufficient for an emergency landing this is not suitable as routine operation. In this paper a solution is presented which uses optical flow techniques for position stabilization in the moment just before the touch down to avoid the inaccuracies from the GPS at this critical moment.