Prescribed performance–based tracking control for quadrotor UAV under input delays and input saturations

In this paper, a semi-global trajectory tracking control scheme is proposed for quadrotor unmanned aerial vehicle (UAV) under time-varying input delays, input saturations, and bounded disturbances. Initially, in order to ensure the desirable control performance that tracking error is limited in a prescribed bound, an error transformation function is presented to transform the constrained problem into a stabilization one. Then, under backstepping control scheme, a state prediction method combined with a dynamic surface control (DSC) is presented to compensate for the effects of input delays, and an auxiliary system is designed to tackle the input saturations, which are further to deal with input delays and input saturations in both position system and attitude system of quadrotor UAV. Particularly, the Euler angle is constrained to avoid the singular points of the attitude system. Besides, based on Lyapunov stability theory, it can be verified that all signals in the closed-loop system of the quadrotor UAV are semi-globally ultimately uniformly bounded (UUB) and the tracking errors are restrained in the prescribed bounds. Finally, by choosing some appropriate parameters, the simulation results based on quadrotor UAV model are given to verify the effectiveness of the proposed control scheme.