Observer-based fixed-time control for nonlinear systems with enhanced nonsingular fast terminal sliding mode

In this paper, we develop a novel observer-based fixed-time control for a class of uncertain nonlinear systems. First, a fast terminal sliding mode disturbance observer is constructed, which can guarantee accurate estimation of the lumped disturbance in fixed time. Next, using a new fixed-time stable system, a novel enhanced nonsingular fast terminal sliding mode manifold with bounded convergence time independently of the initial states is presented to enhance system convergence rate. Subsequently, by using the presented fast terminal sliding mode disturbance observer and enhanced nonsingular fast terminal sliding mode manifold, the observer-based fixed-time control scheme is developed, which can achieve system stabilization within fixed time and offer global fast convergence property. The fixed-time convergence of the system states under the proposed control approach is analyzed by utilizing the Lyapunov stability theory. Finally, corresponding simulation results are provided to confirm the feasibility and superiority of the new control strategy.