Automatic safe area detection in three-dimensional airspace

As a consequence of the growing market of unmanned air vehicles, new challenges and questions arise regarding safety, reliability and their participation in commercial air space. In order to reduce the probability of damage to third parties on ground and in air, the integration of risk mitigation strategies into the flight control software has been initiated. Flight missions beyond visual line of sight demand capabilities from unmanned air systems to detect and avoid obstacles and to stay within certain flight area boundaries. Due to the three-dimensional nature of air space, specified by aviation authorities, it is beneficial to detect the position of the unmanned air vehicle automatically regarding three-dimensional space. This paper introduces a new safe area detection algorithm for any unmanned air vehicle in three-dimensional air space boundaries. The presented approach determines, if the air vehicle is inside or outside of a three-dimensional flight area. Thus, the safe area detection algorithm monitors the position of the moving unmanned air vehicle with respect to the flight area and alerts the flight operator, if the air vehicle leaves. The flight area consists of a flight zone including non-flight zones. The zones are specified in three-dimensional space by vertices, which are defined by WGS84 or cartesian coordinates. The paper comprises the procedure of the flight area definition by the flight operator and the mathematical approach of the safe area detection algorithm up to its verification in model-in-the-loop simulations.