|Observer-based Fixed-time Fuzzy Adaptive Output Feedback Tracking Control for a Class of Nonlinear Systems
Yujing Shi*, Chen Wang, and Shanqiang Li
International Journal of Control, Automation, and Systems, vol. 20, no. 8, pp.2569-2582, 2022
Abstract : This paper is concerned with the fixed-time tracking control problem for a class of uncertain strictfeedback nonlinear systems with external disturbances and unmeasured states. The fuzzy state observer and fuzzy logic systems (FLSs) are adopted to estimate the unmeasurable states and approximate the unknown nonlinear functions, respectively. To improve the performance of the system, we attempt to introduce a disturbance observer into the design of the controller. A first-order filter is applied to avoid the computational complexity problem in the backstepping scheme. Subsequently, the fixed-time stability of the closed-loop system is guaranteed in the light of the Lyapunov stability theory, and the tracking error can converge to an adjustable domain under the proposed control method. Compared with the existing finite-time control strategy, the settling time of the presented fixed-time control scheme is unrelated to the initial conditions of the system. Finally, two simulation experiments are given to illustrate the effectiveness of the developed control approach.
"Adaptive backstepping control, disturbance observer, fixed-time stability, nonlinear systems, state observer. "