Path tracking and obstacle avoidance of UAVs: Fuzzy logic approach

This paper addresses the problem of how to make a UAV track a given flight trajectory while at the same time avoid unexpected obstacle(s). If the information about the existence of the obstacle is known in advance, the problem can be readily solved by carefully pre-planning the desired flight path for the vehicle. However, obstacle(s) might appear unexpectedly in practical applications, as such the pre-planned flight path might become "misleading" to the vehicle if no correcting action is taken. Furthermore, obstacles might be of any shape (not necessarily a point mass) and might be either inert or hostile (including seeking a collision). How to avoid unexpected, irregular, even moving obstacles while maintaining close path tracking of UAV is an interesting yet challenging problem. In this paper, we explore fuzzy logic based approach to path tracking and obstacle avoiding. We consider the case that obstacles are either still or moving and appear along the predetermined flight path unexpectedly. By using suitable sensors we identify the relative distance between the vehicle and the obstacle and make timely adjustment to the pre-planned flight path. Fuzzy logic control algorithms are developed to achieve close path tracking while avoiding obstacles. Simulation studies on multiple obstacles with various shapes are conducted and the effectiveness of the proposed method is verified. © 2005 IEEE.