A dynamic output feedback controllers for mismatched uncertain variable structure systems

This paper proposes a dynamic output feedback controllers for variable stru cture systems. It is based on the concept of output feedback controllers, i ntroduced by Zak and Hui (IEEE Trans. Automat. Control AC-38 (1993) 1509) a nd Kwan (IEEE Trans. Automat. Control AC-41 (1996) 1691) for matched uncert ain variable structure systems in M which the state is unavailable and no e stimated slate is required. In this paper, we extend this idea to a class o f mismatched uncertain variable structure systems. A modified variable stru cture controllers is derived to guarantee the existence of the sliding mode by using output feedback only. The stability of the equivalent reduced-ord er system in the sliding mode is assured under certain conditions. (C) 2001 Elsevier Science Ltd. Ail rights reserved.