  We study a multi-agent output regulation problem, where not all agents have
access to the exosystem's dynamics. We propose a distributed controller that
solves the problem for linear, heterogeneous, and uncertain agent dynamics as
well as time-varying directed networks. The distributed controller consists of
two parts: (1) an exosystem generator that creates a local copy of the
exosystem dynamics by using consensus protocols, and (2) a dynamic compensator
that uses (again) consensus to approach the internal model of the exosystem and
thereby achieves perfect output regulation. Our approach leverages methods from
internal model based controller synthesis, multi-agent consensus over directed
networks, and stability of time-varying linear systems; the derived result is
an adaptation of the (centralized) internal model principle to the distributed,
networked setting.
