Title: Robust Nonlinear Control Systems: Theory and Design
Speaker: Professor R. Freeman
Speaker Info: Northwestern U.
A mathematical model used for the design of a controller for a physical system does not usually describe every possible behavior of the system. A primary task of feedback control is to achieve performance objectives despite discrepancies between the model and the actual system. One method of robust control design is to assume that the system is accurately described by some unknown member of a given set of models and then to design a controller which meets the performance objectives for every model in the set. This set of models is usually characterized by a nominal model in feedback with an uncertain system belonging to a prescribed uncertainty set. The linear robust control designs developed in recent years are based on the assumption that the nominal model is linear. This assumption can lead to overly conservative designs because any nonlinearity in the system must be considered as part of the uncertainty set, even if the nonlinearity is well known. In contrast, methods of robust nonlinear control allow for a nonlinear nominal model and can thereby reduce the effective size of the uncertainty set. The speaker will present recent advances in the development of techniques for the design of robust nonlinear control systems.Date: Friday, November 20, 1998