Cooperative global robust output regulation for lower triangular nonlinear multi-agent systems under directed graph

In this paper, we study the cooperative global robust output regulation problem for nonlinear multi-agent systems in lower triangular form under directed graph. We first establish a few technical lemmas for laying the foundation of a block global backstepping approach, and then, under some standard assumptions on the system dynamics and the graph topology, we solve the problem via a distributed control law by combining the internal model technique with a distributed gain assignment technique. Our result contains a few existing results as special cases.