Abstract
This paper considers the problem of stabilizing large-scale systems by means of decentralized dynamic controllers. It is assumed that the system is composed of a number of subsystems and the decentralized control law is conformable to the subsystems. The local controllers are based on observers for isolated subsystems, but it is not expected that the observers estimate the subsystem states when the subsystems are interconnected. The set of local observers is usually not an observer for the overall system. In this paper, each observer is constructed using the idea of perfect regulation so that its state is sufficiently close to the subsystem state against the interconnection effects from other subsystems, and thus decentralized state feedback can be applied approximately. The condition under which this is possible is presented, that provides stabilizability conditions when combined with stabilization results by state feedback.
