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

Abstract

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.

Observer-based free-will arbitrary time sliding mode control for uncertain robotic manipulators

“…In Chalanga et al (2016); Rabiee et al (2019), finite-time sliding mode disturbance observers were designed based on adaptive and super-twisting techniques, respectively. Additionally, in recent years, several fixed-time disturbance observers (Ni et al, 2017; Pan and Zhang, 2022; Zhang et al, 2019) have been proposed for estimating the external disturbances of the system in a fixed time. However, the above perturbation observers can only guarantee finite-time or fixed-time estimates of system perturbations, and few studies have addressed the design of predefined-time observer.…”