Failure-robust distributed controller architectures

In this paper we consider the problem of designing a controller that is distributed to n processing nodes associated with n collocated control input-measurement output pairs of a given plant. We seek necessary and sufficient conditions so that a controller, distributed in this form, can provide pre-specifled performance levels when certain nodes fail. Based on the Youla-Kucera parameterization, the problem can be converted to a convex, structured in Q problem, the solution of which provides a construction for the distributed controller. In addition to nodal failures, we consider the effect of communication noise existing in the transmission of information among nodes, to the regulated variable, and show that this can be precisely captured also in a convex in Q problem.