Consensus of Multi-Agent Systems Under Unbounded Communication Delays Via Adaptive Distributed Observers

This article considers the leader-following consensus problem of multiagent systems subject to unbounded distributed communication delays under the condition that only the neighboring agents of the leader have access to the information on both the system matrix and the state of the leader. A novel adaptive distributed observer is proposed to estimate both the system matrix and the state of the leader under unbounded distributed communication delays, without requiring that the information of the unbounded delays is known a priori. A key technical result is first established, and a novel distributed controller is then developed based on the proposed distributed observer. It is shown that the resulting closed-loop system achieves the desired consensus. Finally, the effectiveness of the theoretical results is validated by two simulation examples. © 2025 IEEE.