Nonlinear Output Feedback Control: Performance and Robustness

Michigan State University, East Lansing MI

Investigators

Abstract

It is proposed to conduct research on the design of output feedback control of nonlinear systems. In the past several years, the principal investigator's team has introduced and developed a new approach to this problem that combines high-gain observers with saturation nonlinearities. The approach proved useful in achieving fundamental progress in semiglobal stabilization, sliding-mode control, servomechanisms, and adaptive control. The earlier work has emphasized robustness and asymptotic behavior, which quite often come at the expense of the transient performance. The goal of this proposal is to develop new tools for nonlinear design that ensure acceptable transient performance, while ensuring robustness and a desired asymptotic behavior. There are two main thrusts in the proposal. The first one it to develop the tool of conditional integrators and ser- vocompensators, which was recently introduced by the principal investigator's team, to a much wider class of nonlinear systems and design methods. The second one is to develop a logic-based switching control strategy for a class of nonlinear systems, as an alternative to robust and adaptive control, in order to improve performance in the face of large model uncertainties. The class of nonlinear systems under consideration arises in many applications such as mechan- ical systems, aircraft control, and electric motor drives. Earlier results have been applied to the control of induction motors and a mechanical system known as the pendubot. It is planned to continue using these two systems as testbeds for the new techniques.