Output synchronization of linear multi-agent systems under constant disturbances via distributed integral action

This paper solves the output synchronization problem for groups of identical linear agents subject to constant external disturbances. We propose novel distributed control laws with integral action. In a first step, we assume that each agent has access to its own state. Then, we present observer-based implementations for the cases where each agent has only access to its output or to a relative output measurement with respect to its neighbors in the graph. We show that this method can also be used in order to solve a cooperative distributed tracking problem, where each agent has a local reference signal and the group objective is to synchronize to the sum or average of all their references. Numerical examples illustrate the results.