A Condition for Certainty Equivalence Output Feedback Stabilization of Nonlinear Systems

Direct
certainty equivalence results for output feedback stabilization of nonlinear systems are proposed. The first result is a simple extension of the
indirect
approach used in a paper by Praly and Arcak. The second result allows to deal with observers yielding nonuniformly converging estimates with respect to the norm of (a subset of) the system state. Application of these results with the reduced-order observer of Karagiannis are discussed.