Distributed observer-based close formation control for UAV swarm under outside disturbances and wake interferences

Abstract

This work investigates the issue on distributed close formation tracking control for a class of fixed-wing UAVs under prescribed performance, outside disturbances, and wake interferences. Firstly, by considering the existence of uncertain terms, a second-order kinematical model is established for each UAV system. Secondly, in order to ensure the safe flight of each UAV, an improved prescribed performance method is proposed to constrain the tracking error within the given restraint. Thirdly, based on the exogenous models of the outside disturbance and wake interference, two kinds of distributed disturbance observers are respectively presented to derive their estimations, in which the approximations of the uncertainties are included. Fourthly, according to the safe distance, estimations of the disturbances and uncertainties, and tracking error, a distributed cooperative controller is designed and an overall closed-loop system is deduced on the basis of Kronecker product. Then, a sufficient condition is established to ensure the asymptotical stability for the close-loop system and later, an easy-to-test method of checking the controller gains, observer ones, and adaptive law is presented. Finally, the effectiveness and superiorities of the proposed control strategy are verified by resorting to a simulated example.