Fixed-time Second-order Sliding Mode Control Based on Disturbance Observer for UAV Formation*

In this paper, a kind of Unmanned aerial ve-hicle(UAV) formation controller with external disturbance is proposed. Firstly, a fixed-time disturbance observer(FTDO) is designed through fixed-time sliding mode(FTSM), which enable each follower identify the external disturbance effectively. On this basis, a fixed-time second-order sliding mode controller is designed to control each follower to form and maintain a preset formation and follow the leader within a fixed time unrelated to the initial state of the system, while greatly reduces the chattering problem of conventional sliding mode controller. The stability of the FTDO and proposed controller is proved by Lyapunov theory, and the effectiveness is verified by simulation.