The Decentralized Control Expanding System Problem

Suppose a controlled system denoted by Sold exists with the property that robust tracking and regulation occurs in each of the system´s local control agents. We wish to examine the conditions under which a new subsystem and a new set of local control agents denoted by Snew can be connected to Sold´ so that the new outputs and previous outputs are regulated, without the need for retuning the original control agents. This problem is a generalizaiton of the results obtained in [3] which deals with the case when the control agents of Snew are centralized.