  This paper focuses on the consensus and formation problems of multiagent
systems under unknown persistent disturbances. Specifically, we propose a novel
method that combines an existing consensus (or formation) algorithm with a new
controller. The new controller has an integral action that produces a control
input based on an error signal locally projected onto the column space of the
graph Laplacian. This action allows agents to achieve a consensus or a
predetermined formation objective under constant or time-varying disturbances.
This study has analyzed the stability properties of this architecture and
provides several illustrative examples to demonstrate the proposed approach.
