On H∞ and H2 performance regions of multi-agent systems

This paper addresses the distributed H"2 and H"~ control problems for multi-agent systems with linear or linearized dynamics. An undirected multigraph with loops is used to represent the communication topology of a multi-agent network. A distributed controller is designed, based on the relative states of neighboring agents and a subset of absolute states of the networked agents. The notions of H"~ and H"2 performance regions are introduced and analyzed, respectively. A necessary and sufficient condition for the existence of a controller yielding an unbounded H"~ performance region is derived. A multi-step procedure for suboptimal H"~ controller synthesis is presented. It is also shown that the H"~ performance limit of the network under the distributed controller is equal to the minimal H"~ norm of a single agent achieved by using the state feedback controller. It is finally shown that, contrarily to the H"~ case, the H"2 performance limit scales with the number of agents in the network.