Output Consensus Control of Nonlinear Non-minimum Phase Multi-agent Systems Using Output Redefinition Method

This paper concerns the problem of output consensus in nonlinear non-minimum phase systems. The main contribution of the paper is to guarantee achieving consensus in the presence of unstable zero dynamics. To achieve this goal, an output redefinition method is proposed. The new outputs of agents are functions of original outputs and internal states and defined such that the dynamics of agents are minimum phase. However, since the main objective is to achieve consensus on original outputs of agents, the consensus invariant set in the new coordinate of the agents dynamics should be defined such that if the new states of the agents converge to this invariant set, the output consensus in original system is achieved. On the other words, achieving consensus in minimum phase system with redefined output is equivalent to output consensus in original system. After defining the proper invariant set, a consensus protocol is designed to guarantee that the redefined outputs and the internal states to this set. Theoretical results are mathematically proved based on Lyapunov criterion. Numerical examples are employed to show the effectiveness of the proposed approach.