2000a). Output feedback control of stabilizable and incompletely observable systems: Theory

This paper introduces a new approach for output feed-back stabilization of SISO systems which, unlike most of the techniques found in the literature, does not use high-gain observers and control input saturation to achieve separation between the state feedback and observer designs. Rather, we show that by using non-linear observers, together with a projection algorithm, the same kind of separation principle is achieved for a larger class of systems, namely stabilizable and in-completely observable plants. Furthermore, this new approach avoids using knowledge of the inverse of the observability mapping, which is needed by most tech-niques in the literature when controlling general stabi-lizable systems.