@techreport{oai:kyutech.repo.nii.ac.jp:00000687,
 author = {Ito, Hiroshi and 伊藤, 博},
 month = {Jun},
 note = {This paper considers global robust stabilization of a class of nonlinear systemsvia output feedback. A new approach to output-feedback backstepping is proposed. Theapproach provides us with a systematic design procedure which can handle output-feedbackstabilization problems of strict-feedback nonlinear systems in a uni ed way. More importantly,the approach by itself has a mechanism of achieving robust stabilization against ageneral class of structured uncertainties in the procedure. Compared with the state-feedbackglobal stabilization, the the class of uncertainties which has been treated by the literatureof global robust stabilization problems via output feedback is quite restricted in spite of thepractical importance of considering various locations and structure of uncertainties. The approachpresented in this paper can be considered as an successful extension of the author'sstate-dependent design for state-feedback backstepping to the output feedback case. Thereby,this paper shows the power of the general concept of state-dependent scaling design for nonlinearsystems control by looking at output-feedback stabilization problems, especially in abackstepping manner. The scaling approach allows us to treats both static and dynamic uncertaintyin an uni ed way and , in addition, be able to clarify the di erence between their consequences of stabilization in a simple way. The output feedback design proposed also inheritsadvantages of SD scaling design such as automatic computation of backstepping basedon optimization. Controllers in this paper are dynamic feedback which consists of observerand feedback gain(or controller). The essential di erence between nominal stabilization androbust stabilization is described. It is shown that observer design cannot be separated globallyfrom controller design. The observer should be designed strong enough to compensate\onlinear size of the uncertainty on the entire state-space. The coupling is natural andinevitable in robust stabilization as it is for linear systems. In addition, for nonlinear systems,nonlinearity of the coupling is crucial for global stabilization which cannot be compensatedglobally by either feedback-gain or observer-gain independently. This fact contrasts with nominalstabilization in which it is possible to stabilize the whole system globally by designingcontroller strong enough whenever the observer dynamics by itself design to be only stable(or,vice versa). Strong observers required for robust stabilization may not exist unless the outputhave the full information of the state. If the nonlinear size of uncertainties are small enough,the global robust stabilization can be certainly achieved. This paper shows the condition ofallowable size and nonlinearity of uncertainties for which robust stabilization can be done viabackstepping. The condition is considered as the index  which describes the largest allowablesize of uncertainty in robust stabilization via linear H1 control. Indeed, for linear systems,the condition of  has coupling between feedback gain and observer design(or Riccati inequalities).In addition to the coupling, the condition of the uncertainty size in this paper exhibitsa recursive form because of backstepping. Another feature of the output backstepping proceduresin this paper is that it does not require Young's inequality. Instead, the paper uses theSchur complements formula which gives a necessary and su cient condition for negativity ofa quadratic form. This paper also proposes a novel recursive procedure of robust observerdesign, which resembles backstepping or forwarding for controller design.},
 title = {State-Dependent Scaling Design for Robust Backstepping via Output Feedback 12},
 year = {1999},
 yomi = {イトウ, ヒロシ}
}