Cascade result of Input-Output Stability for Index One Descriptor Control Systems

Abstract

We study the recently introduced notion of input-output stability, which is a robust variant of the minimum-phase property for general smooth nonlinear control systems. The purpose of this paper is to investigate how the input-output stability property behaves under series connections of several subsystems. We will prove two lemmas. The first one says that the cascade of a 0-detectable descriptor system with an input-output stable descriptor system is weakly 0-detectable, which is a result of independent interest. The second lemma is a direct generalization of the first one.