Finite-time control for a UAV system based on finite-time disturbance observer

Abstract

This paper addresses the problem of finite-time control of an unmanned aerial vehicle (UAV) system subject to input saturation and external disturbance. The dynamic model of the UAV is described in detail using Newton-Euler equations. A finite-time nonlinear disturbance observer (NDO) is presented to estimate external disturbance acting on altitude and attitude channels of the UAV. It is shown that the observation error can converge to zero in finite time. To stabilize the UAV system with input saturation, an auxiliary system is designed to compensate for the saturation effect. Furthermore, a fast terminal sliding mode controller (FTSMC) is developed to achieve trajectory tracking control/stabilization of the UAV. It is proved that the tracking errors for desired altitude and attitude are guaranteed to converge to zero in finite time. Simulations and experiments have been carried out to illustrate the robustness and effectiveness of the proposed control algorithm, where its superiority compared with active disturbance rejection control (ADRC) has been demonstrated.