Fuzzy Adaptive Hybrid Control And Stability Analysis For Nonlinear Constrain Systems

For some classes of uncertain nonlinear systems,by utilizing the property of fuzzy logic systems,adaptive backstepping control design technique and Lyapunov stability theory,this thesis studies fuzzy state observer design,serial–parallel estimation models design,adaptive fuzzy hybrid control design methods and the stability analysis of the control systems.The major contents of this thesis are as follows:(1)For a class of single-input and single-output(SISO)non-strict feedback systems with constant constraint and unmeasured states,an adaptive fuzzy hybrid control design scheme is investigated.By using fuzzy logic system to approximate the unknown dynamics,a fuzzy state observer is designed.Based on the designed fuzzy state observer,a serial-parallel estimation model is established.By combining commend filter technique with the adaptive backstepping control design algorithm,an adaptive fuzzy hybrid output feedback control design method is proposed.Based on Barrier Lyapunov stability theory,it is proved that the controlled system is stable and the tracking errors converge to a neighborhood of zero,respectively.A numerical example is used to verify the effectiveness of the proposed control scheme.(2)For a class of single-input and single-output uncertain nonlinear systems with time varying constraints,the fuzzy logic systems are used to approximate the unknown nonlinear functions.By combining the prediction error between system state and serial–parallel estimation model,a fuzzy adaptive hybrid control design method is proposed.Based on Lyapunov stability theory,it is proved that the stability of the controll system and the convergence of the tracking errors.A numerical example is used to verify the effectiveness of the proposed control scheme.(3)For a class of multi-input and multi-output uncertain nonlinear systems with time varying constraints,an observer-based adaptive fuzzy hybrid control design method is presented.By adopting fuzzy adaptive backstepping control design and prescribed performance techniques,a prescribed performance fuzzy adaptive output-feedback control design scheme is proposed.Based on Lyapunov stability theory,it is proved that all the signals of the closed-loop system are semi-globally uniformly ultimately bounded,and the tracking errors converge to the prescribed performance boundedness.A numerical example is used to verify the effectiveness of the proposed control scheme.