  This paper considers the distributed consensus problem of multi-agent systems
with general continuous-time linear dynamics. Two distributed adaptive dynamic
consensus protocols are proposed, based on the relative output information of
neighboring agents. One protocol assigns an adaptive coupling weight to each
edge in the communication graph while the other uses an adaptive coupling
weight for each node. These two adaptive protocols are designed to ensure that
consensus is reached in a fully distributed fashion for any undirected
connected communication graphs without using any global information. A
sufficient condition for the existence of these adaptive protocols is that each
agent is stabilizable and detectable. The cases with leader-follower and
switching communication graphs are also studied.
