Finite Time Fuzzy Adaptive Output-feedback Control For Uncertain Nonlinear Systems

For some classes of uncertain nonlinear systems,by utilizing adaptive backstepping control design and finite-time Lyapunov stability theory,this thesis studies finite-time fuzzy adaptive output-feedback control design problems,the stability problems of controlled systems and the convergence of the tracking errors.The major contents of this thesis are as follows:(1)A finite-time fuzzy adaptive output-feedback control design problem is studied for a class of single-input and single-output(SISO)nonlinear systems with unknown time-varying delay.A state observer is designed via fuzzy logic systems approximating the unknown functions.By using fuzzy adaptive backstepping control design technique,an observer-based finite-time output feedback control design technique is developed.Based on the finite-time Lyapunov-Krasovskii functional stability theory,it is proved that the issues of the stability of the controlled system and the convergence of the tracking errors.(2)A finite-time fuzzy adaptive output-feedback control design problem is studied for a class of multi-input and multi-output(MIMO)nonlinear non-strict feedback systems.By introducing dynamic surface control(DSC)technique into adaptive backstepping control design algorithm,an observer-based finite-time fuzzy adaptive control design method is presented,which overcomes the problem of “explosion of complexity” existing in traditional control design process.Based on finite-time Lyapunov stability theory,it is proved that the problems of the stability of the controlled system and the convergence of the tracking errors.(3)A finite-time fuzzy adaptive output-feedback tracking errors-constraint control design problem is studied for a class of MIMO nonlinear non-strict feedback systems with unknown dead zone.To deal with unknown dead zone problem,a dead zone compensator is designed.By adopting fuzzy adaptive backstepping control design and prescribed performance techniques,a prescribed performance finite-time output-feedback control design scheme is proposed.Based on finite-time Lyapunov stability theory,it is proved that all the signals of the closed-loop system are semi-global practical finite-time stability(SGPFS),and the tracking errors converge to a prescribed performance boundedness.(4)A finite-time fuzzy adaptive output-feedback decentralized control design problem is studied for a class of interconnected nonlinear large-scale systems with output-constraint.By using commend filter and adaptive backstepping control design algorithms,an observer-based fuzzy adaptive finite-time decentralized control design scheme is proposed.Based on finite-time Lyapunov stability theory,it is proved that the problems of the stability of the controlled system and the convergence of the tracking errors.(5)A finite-time fuzzy adaptive state feedback control design problem is studied for a class of high-order nonlinear strict-feedback systems.Fuzzy logic systems(FLSs)are utilized to approximate the packaged unknown nonlinear functions.By adopting adding a power integrator and adaptive backstepping control design algorithms,a finite-time fuzzy adaptive control design method is proposed by constructing a novel Lyapunov function.The convergence of the tracking errors and stability of the closed-loop system are proved in the sense of the finite-time Lyapunov stable theory.(6)Numerical and application simulation examples are provided for the above control methods.The simulation results are given to further confirm the effectiveness of the presented control method and theories.