In this paper we propose a new class of output feedback variable structure controllers and state estimators (observers) for uncertain dynamic systems with hounded uncertainties. No statistical information about the uncertain elements is assumed. A variable structure systems (VSS) approach together with the geometric approach to the analysis and synthesis of system zeros are employed in the synthesis of the proposed output feedback controllers and state estimators. The role of system zeros in the output feedback stabilization and state estimation, using the VSS approach, is discussed. Numerical examples included illustrate the feasibility of the proposed stabilization and state estimation schemes.


Output feedback, State estimation, Uncertain systems, Variable structure control, System zeros

Date of this Version

November 1991