Passivity Approach And Its Application To A Class Of Nonlinear Systems

Originated from electrical network, passive theory owns extensive engineering backgrounds, and it has many important applications in adaptive control, nonlinear control and robust control, etc. Although a number of recursive design procedure for its applications and extensions are being reported, the relative degree one and weakly minimum-phase conditions have been major obstacles for the passification of the given system. This thesis focuses on the design for a dynamic passifier which can remove the obstacles above and presents some new results in broadening passivity theory.In the top two chapters of this thesis, the born and development of passive theory are reviewed and the main results of passive-based control for nonlinear systems are revisited. Some approaches and problems are given in the study of the passification problems and the main work of this thesis is introduced.Next, we study some different models of nonlinear system separately. The 3rd chapter addresses the passification problem of a class of nonlinear affine system, which is characterized by their structural properties such as relative degree higher than one and non-minimum phaseness. We construct the parallel compensator for the passivation which is more suitable for the output feedback stabilization. For linear system with the same properties, the construction procedure is reduced to problems of solving some LMIs.In the 4^th chapter, for the cascade nonlinear system with relative degree greater one, the feedback stabilization via feedback passification is concerned. In this paper, some Hurwitz differential operator is cascaded to compensate the original system and to make the relative degree equal to one, then the classical feedback passification approach is still available.In certain cases, solely series or solely feedback passification may not be possible or desirable. So the 5th chapter presents a hybrid compensator which is a combination of series and feedback passification or the switch between the parallel and feedback passification. These alternate configurations for hybrid passification would broad the application of the passive theory.In the end, we conclude this thesis and present the future work.Besides, simulations are made for main design schemes and the results demonstrate the effectiveness of the proposed approaches.