A Biologically Inspired, Vision-based Guidance System for Automatic Landing of a Fixed-wing Aircraft

We describe a guidance system for achieving automatic landing of a fixed-wing aircraft in unstructured outdoor terrain, using onboard video cameras. The system uses optic flow information for sensing and controlling the height above the ground, and information on the horizon profile, also acquired by the vision system for stabilizing roll and controlling pitch, and additionally, if required, for the control and stabilization of yaw and flight direction. At low heights, when optic flow is unreliable, stereo information is used to guide descent close to touchdown. While rate gyro information is used to augment attitude stabilization in one of the designs, this is not mandatory and it can be replaced by visual information. Smooth, safe landings are achieved with a success rate of 92.5%. The system does not emit active radiation and does not rely on any external information such as a global positioning system or an instrument landing system. (C) 2014 Wiley Periodicals, Inc.