  In this paper, a novel two-level framework was proposed and applied to solve
the output average consensus problem over heterogeneous multi-agent systems.
This approach is mainly based on the recent technique of system abstraction.
For given multi-agent systems, we first constructed their abstractions as the
upper level and solved their average consensus problem by leveraging well-known
results for single integrators. Then the control protocols for physical agents
in the lower level were synthesized in a hierarchical way by embedding the
designed law for abstractions into an interface between two levels. In this
way, the complexity coming from heterogeneous dynamics of agents is totally
decoupled from that of the coordination task and the communication topologies.
An example was given to show its effectiveness.
