Observer-Based Adaptive Fuzzy Tracking Control for Strict-Feedback Nonlinear Systems With Unknown Control Gain Functions

• Published in: IEEE transactions on cybernetics Vol. 50; no. 9; pp. 3903 - 3913
• Main Authors: Tong, Shaocheng, Min, Xiao, Li, Yuanxin
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.09.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adaptive backstepping output-feedback controller design; Adaptive control; Adaptive systems; Backstepping; Basis functions; Closed loop systems; Computer simulation; Control design; Design; Feedback control; Fuzzy control; Fuzzy logic; Fuzzy systems; fuzzy-logic systems (FLSs); Liapunov functions; Nonlinear control; Nonlinear systems; Observers; Output feedback; Recursive methods; state observer design; State observers; Tracking control; Tracking errors; uncertain nonlinear systems
• ISSN: 2168-2267; 2168-2275; 2168-2275
• DOI: 10.1109/TCYB.2020.2977175

This article investigates the adaptive fuzzy output-feedback backstepping control design problem for uncertain strict-feedback nonlinear systems in the presence of unknown virtual and actual control gain functions and unmeasurable states. A fuzzy state observer is designed via fuzzy-logic systems, thus the unmeasurable states are estimated based on the designed fuzzy state observer. By constructing the logarithm Lyapunov functions and incorporating the property of the fuzzy basis functions and bounded control design technique into the adaptive backstepping recursive design, a novel observer-based adaptive fuzzy output-feedback control method is developed. The proposed fuzzy adaptive output-feedback backstepping control scheme can remove the restrictive assumptions in the previous literature that the virtual control gains and actual control gain functions must be constants. Furthermore, it can make the control system be semiglobally uniformly ultimately boundedness (SGUUB) and keep the observer and tracking errors to remain in a small neighborhood of the origin. The numerical simulation example is presented to validate the effectiveness of the proposed control scheme and theory.