Horizontal Path Following Kinematic Controller for a Small Fixed-wing UAV Using Backstepping and Parameter Optimization

In this paper, the problem of horizontal path following of a small fixed-wing unmanned aerial vehicle (UAV) is studied based on the combined kinematic/dynamic model. First, a stable kinematic path following control law is designed. Second, the backstepping technique is applied to derive the roll angle command by considering the closed-loop roll dynamics. The stability of the corresponding nonlinear system is guaranteed by Lyapunov stability arguments. Third, two key parameters of the control law which will influence the path following performance have been analyzed. Two fuzzy logic based controllers have been designed to optimize the parameters to improve the path following performance (PFC_FL), where the stability of the corresponding nonlinear system is still kept. The simulations of square and circular paths following control of an Aerosonde UAV have been studied. The path following performances of the proposed control law with parameter fixed (PFC), PFC_FL method, vector field (VF) method, and pure pursuit with light-of-sight (PLOS) method were compared. The proposed PFC_FL method can make the UAV have the longest length of corresponding effective flight path and the shortest total convergence time. The PFC_FL can also have much smaller error overshoots than those by using the method PFC during route switching.