Adaptive Control For Time-Delay Nonlinear Systems In Nested Lower Triangular Form

In the modern control field，adaptive control for nonlinear systems is one of theresearch focuses．However，what the most of existing achievements deal with is theSISO nonlinear systems or the systems in lower triangular form．The achievementsfor a class of nested lower triangular structural MIMO nonlinear systems which is notin lower triangular form，has been receiving little attention to the best of authors’knowledge．On the other hand，time delay phenomenon widely exists in variousengineering systems．Although many results of the time-delay nonlinear systems wehave got，adaptive controllers design mostly depend on the time delays or the upperbounds of the time delays and their derivatives．In practice，the delays are usually notexactly known．Adaptive control of nonlinear systems with unknown time delays hasan important significance．In this dissertation，based on the current research findings，a robust adaptive control problem is studied for a class of nested lower triangularstructural time-delay nonlinear systems with uncertainties by utilizing extendedBackstepping method and the tuning function technique and appropriateLyapunov-Krasovskii functional．The main contributions of this dissertation can besummarized as follows：In the first chapter，we give the research background and the significance for thissubject．Some achievements both at home and abroad are introduced．In the second chapter，an adaptive control design procedure is presented for aclass of nested lower triangular structural time-delay nonlinear systems．Not only thesystems overcome the restriction of the lower triangular form，but also all theparameters of the systems to be controlled and the upper bounds of the time delaysand their derivatives are supposed to be unknown．By coordinate transformation，the nonlinear systems are translated into the systems whose structure are lowertriangular．Using appropriate Lyapunov-Krasovskii functional and the tuning functiontechnique and an extension of Backstepping，the adaptive controllers are designedrespectively such that the states and all other signals of the corresponding closed-loop systems are bounded．The simulation results are given to illustrate the feasibility ofthe proposed approach．In the third chapter，we extend the systems of the chapter two to the situationthat the systems contain simultaneously unknown parameters and structuraluncertainties and unknown time delays．A robust adaptive problem is studied for aclass of nested lower triangular structural time-delay nonlinear systems withuncertainties．A numerical example is presented to demonstrate the effectiveness ofthe proposed method．In the fourth chapter，the whole dissertation is summarized and propose the nextresearch direction．...