Plug-and-play control of interconnected systems with a changing number of subsystems

This paper proposes a new method for designing decentralised controllers of interconnected systems with a changing number of subsystems. When a new subsystem is added to an existing interconnected system, the control station of this subsystem should be designed by the design agent of this new subsystem based only on local information and some gathered model information over the network. As the dynamics of the overall system depends upon all existing subsystems, the main difficulty of this design problem is to ensure the stability of the overall interconnected system based on limited information and, furthermore, to evaluate the overall input-output performance locally. The main results of this paper are conditions that can be used to analyse the overall system by means of a limited amount of model information. As a consequence, the new subsystem can be “plugged in”, its design agent collects relevant model information over the network to check the conditions and the new control station “plays” together with the existing controllers. The method is illustrated by its application to a multizone furnace for crystal growth.