Development of Flight Guidance System of a Small Unmanned Aerial Vehicle (UAV)

This paper presents the development of a guidance system for a small Unmanned Aerial Vehicle (UAV) system which combines a waypoints following and an obstacle avoidance systems so that the UAV has a capability to operate in an environment whose ground condition is not completely known. The waypoints following system works by adopting the VOR-Hold approach, in which a correction command will be produced to reduce the angle difference between the desired path and the line connecting the actual UAV position and the subsequent destination point. An avoidance algorithm is developed and integrated with the path following system. In case of the UAV faces an obstacle lying on its flight path, then the avoidance system will generate a set of new waypoints for correcting the flight path, so that the UAV can avoid the obstacle and then returns to the previous flight path. The proposed avoidance approach bases its algorithm on the utilization of ellipsoid geometry for defining a restricted zone containing the obstacle, which is assumed to be already identified by the detection system. When the restricted ellipsoid zone has already been established, the algorithm then computes the locations of new waypoints on the edge of the ellipsoid. The algorithm then is simulated and evaluated in some cases representing situations when an UAV has to avoid obstacles during its flight to a predefined destination.