Global Robust Output Regulation for High-order Unknown Nonlinear Multi-agent Systems with Unknown Control Directions

Abstract

In this paper, we study the global robust output regulation for a class of high-order unknown nonlinear multi-agent systems with unknown control directions and unknown exogenous disturbances. Comparing to the current results, the challenge existed in this paper is that the exogenous disturbance does not have explicit expression but only the unknown upper bound. A Nussbaum-type function is adopted in the proposed control protocol to resolve the problem of unknown control directions. The critical contribution of this paper is to use adaptive control technique develop a novel distributed adaptive control protocol based on relative output information without using global information of the topology. It is proved that all variables in the closed-loop system are bounded and all followers can asymptotically track the leader in the presence of exogenous disturbances. An example with the well-known Van der Pol oscillator is presented to illustrate the effectiveness of the proposed control protocol.