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International Journal of Control, Volume 87, Issue 3, Page 524-536, March 2014.

International Journal of Control, Volume 87, Issue 6, Page 1163-1171, June 2014.

International Journal of Control, Volume 87, Issue 6, Page 1103-1116, June 2014.

International Journal of Control, Volume 87, Issue 6, Page 1208-1215, June 2014.

International Journal of Control, Volume 87, Issue 6, Page 1243-1251, June 2014.

Publication date: March 2014
Source:Systems & Control Letters, Volume 65
Author(s): Dequan Li , Qiupeng Liu , Xiaofan Wang , Zhixiang Yin
This paper studies the quantized consensus problem for a group of agents over directed networks with switching topologies. We propose an effective distributed protocol with an adaptive finite-level uniform quantized strategy, under which consensus among agents is guaranteed with weaker communication conditions. In particular, we analytically prove that each agent sending 5-level quantized information to each of its neighbors, together with 3-level quantized information to itself at each time step, which suffices for attaining consensus with an exponential convergence rate as long as the duration of all link failures in the directed network is bounded. By dropping the typical common left eigenvector requirement for the existence of common quadratic Lyapunov function, we conduct the convergence analysis based on the notion of input-to-output stability. The proposed quantized protocol has favorable merits of requiring little communication overhead and increasing robustness to link unreliability, and it fits well into the digital network framework.

Publication date: March 2014
Source:Systems & Control Letters, Volume 65
Author(s): Lijun Zhu , Zhiyong Chen
In this paper, we consider consensus of a group of heterogeneous agents with nonlinear dynamics in the presence of system uncertainties. It requires that all agent states reach an agreement which is governed by specified reference dynamics. However, the reference dynamics do not generate a specific reference trajectory for feedback regulation for any agent. For this purpose, the proposed controller integrates two fundamental actions, homogenization and consensus, concurrently. On one hand, it asymptotically regulates each individual (heterogeneous, nonlinear, and uncertain) agent dynamics to the common reference dynamics using a robust homogenization technique; on the other hand, it aligns agent trajectories, asymptotically governed by the common reference dynamics, to consensus through network cooperation. The effectiveness of the controller is verified in the rigorous proof and numerical simulation.

Publication date: April 2014
Source:Systems & Control Letters, Volume 66
Author(s): Jiandong Zhu
In this paper, a class of heterogeneous multi-agent systems with directed cycle graphs is investigated. The stabilization and synchronization problems via harmonic control are solved under some conditions and the feedback control gains are constructively designed. Several numerical examples are presented to demonstrate the effectiveness of the proposed method.

Publication date: March 2014
Source:Systems & Control Letters, Volume 65
Author(s): Zhenhua Wang , Juanjuan Xu , Huanshui Zhang
This paper studies the consensusability problem of continuous-time multi-agent systems with time-varying communication delay in undirected network. We design a consensus protocol based on the low gain solution of a parametric algebraic Riccati equation (ARE) and not use the precise information of the amount of time-varying delay. By studying the joint effect of agent dynamic and network topology, sufficient conditions are given for consensus when all poles of the system matrix are on the closed left-half plane. In case of non-zero poles on the imaginary axis, maximal admissible upper bound of the time-varying delay is given in terms of both the agent dynamic and network topology; otherwise, consensus can be achieved for the time-varying delay with arbitrarily large upper bound. Finally, simulation results are presented to demonstrate the effectiveness of the theoretical results.