Adaptive Fuzzy Control And Performance Research Of Nonlinear Systems

Under the framework of fuzzy logic systems, adaptive fuzzy backstepping control andprescribed performance theory, designed fuzzy state observer and adaptive fuzzy prescribedperformance control approach for some classes of uncertain nonlinear systems withunmeasurable states. This thesis systemtically studied stability analysis of the closed-loopsystem. The main research works are state as follows:(1) For a class of uncertain nonlinear systems with unmeasurable states, the fuzzy logicsystems are used to approximate the unknown nonlinear functions, a fuzzy state observer isestablished for estimating the unmeasured states; backstepping control design andincorporated by the predefined performance technique, a new adaptive fuzzy predefinedperformance control method is developed; using Lyapnuov stability theory, the stability ofclosed-loop system is proved. The simulation example with the previous control method isprovided to show the effectiveness of the proposed control approach.(2) For a class of uncertain nonlinear systems with unmodeled dynamics and without themeasurements of the states, the fuzzy logic systems are used to approximate the unknownnonlinear functions, and a fuzzy state observer is designed for estimating the unmeasuredstates; to solve the problem of unmodeled dynamics, the dynamical signal combined withchanging supply function is incorporated; based on adaptive fuzzy Backstepping designtechnique and prescribed performance technique, a robust adaptive fuzzy prescribedperformance control approach is proposed; inoder to avoid repeatedly differentiating, dynamicsurface technique is introduced, another new robust adaptive fuzzy prescribed performancecontrol scheme is developed; using Lyapnuov stability theory, the stability of closed-loopsystem is proved. A simulation example and comparison with the previous control methodsare provided to show the effectiveness of the proposed control approach.(3) For a class of uncertain nonlinear stochastic systems with unmeasured states, thefuzzy logic systems are used to approximate the unknown nonlinear functions, a fuzzy stateobserver is established for estimating the unmeasured states; backstepping control design andincorporated by the predefined performance technique, a new adaptive fuzzy prescribedperformance control method is developed; using Lyapnuov stability theory, the stability ofclosed-loop system is proved. The simulation example with the previous control method isprovided to show the effectiveness of the proposed control approach.(4) For a class of uncertain nonlinear multi-input and multi-output nonlinear systemswith unmeasured states, using fuzzy logic systems to model the uncertain nonlinear systems,a fuzzy adaptive observer is designed for immeasurable states estimations; backsteppingdesign and incorporated by the predefined performance technique, a new fuzzy adaptiveprescribed performance control is developed; using Lyapnuov stability theory, the stability ofclosed-loop system is proved. The detailed simulation results and performance comparisonsare provided to demonstrate the effectiveness of the proposed control approach.