Decentralized iISS Robustification of Interconnected Time-Delay Systems: A Small-Gain Approach*

In this paper we consider the ISS (input-to-state stability) and iISS (integral input-to-state stability) feedback control redesign for interconnected systems described by retarded nonlinear equations with discontinuous right-hand side. We show that it is possible to design a decentralized controller by which the overall closed-loop system is iISS (ISS) with respect to additive disturbances acting on each subsystem whenever the disturbance-free closed-loop system satisfies a small-gain condition.