Distributed output-feedback leader-following consensus of nonlinear multiagent systems

This paper addresses the leader-following consensus problem of a class of strict-feedback nonlinear multiagent systems under undirected follower networks. The leader and the followers are subject to additive input and external disturbances, respectively. A hierarchical output-feedback strategy is proposed, which can be implemented in a fully distributed manner in the sense that neither the Laplacian matrix eigenvalues nor the leader's input bound are required. Firstly, a novel fully distributed observer is introduced to reconstruct the leader's state and unknown input in a user-prescribed finite time, requiring only the leader's output to be available to its neighboring followers. Utilizing the estimated information, a local observer-based output-feedback control protocol is then designed to achieve the state consensus. Subsequently, the robustness of the strategy to measurement noise is analyzed. The proposed strategy advances existing output-feedback fully distributed results in two significant aspects: (1) it is suitable for the scenarios where the leader's state/observer information is not available to any follower and only the leader's output can be obtained by its neighboring followers; (2) the state consensus is achieved in a user-prescribed finite time. Finally, simulation results are provided to validate the efficacy of the proposed consensus approach.