 
Summary: CCEC Seminar
Exploring the Maximum Capability ofExploring the Maximum Capability of
Feedback in Dealing with UncertaintiesFeedback in Dealing with Uncertainties
Professor Lei Guo
President of the Chinese Academy of Mathematics and Systems Science
Thursday, April 14th, 2005
10:00  11:00 am
Engineering II Pavillion
ABSTRACT:
To explore the maximum capability and potential limits of the feedback mechanism, we have to work
in a framework that is somewhat beyond those of the classical ones (including robust and adaptive
control), since we need to study the full capability of the feedback mechanism which includes all
(nonlinear and timevarying) causal mappings, that are not restricted to a fixed feedback law or a set of
specific feedback laws. We need not only to answer what thefeedback can do, but also to answer, the
more difficult question, what the feedback cannot do. In this seminar, we will present several concrete
results towards understanding the capability (and limits) of the feedback mechanism in dealing with
structural uncertainties. In particular, for several basic classes of uncertain nonlinear discretetime (or
sampleddata) dynamical control systems, some "Critical Values" and "Impossibility Theorems"
concerning the capability of feedback will be presented.
About the Speaker:
