Abstract：The consensus problem for a class of heterogeneous multi-agent systems was investigated. A heterogeneous multi-agent system was composed of first-order agents, second-order agents, and Euler-Lagrange agents. The consensus problem of a heterogeneous multi-agent system was discussed when there was a first-order leader agent in the system. By applying the graph theory and Lasalle invariance principle, the proposed consensus protocol was proved right. Then, the consensus problem was also studied when there was a secondorder leader in the system and its velocity information could not be obtained by all followers. An appropriate consensus protocol was presented by designing some distributed state observers. Some examples were presented to illustrate the theoretical results.

Keyword：multi-agent systems;heterogeneous multi-agent systems;consensus;leader-following;distributed state observer;