Hindawi Publishing Corporation Discrete Dynamics in Nature and Society Volume 2012, Article ID 390691, 9 pages doi:10.1155/2012/390691 Research Article Consensus of Discrete Time Second-Order Multiagent Systems with Time Delay Wei Zhu Research Center of System Theory and Application, Chongqing University of Posts and Telecommunications, Chongqing 400065, China Correspondence should be addressed to Wei Zhu, zhuwei@cqupt.edu.cn Received 1 June 2012; Accepted 14 November 2012 Academic Editor: Antonia Vecchio Copyright q 2012 Wei Zhu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The consensus problem for discrete time second-order multiagent systems with time delay is studied. Some effective methods are presented to deal with consensus problems in discrete time multiagent systems. A necessary and sufficient condition is established to ensure consensus. The convergence rate for reaching consensus is also estimated. It is shown that arbitrary bounded time delay can safely be tolerated. An example is presented to illustrate the theoretical result. 1. Introduction The study of information flow and interaction among multiple agents in a group plays an important role in understanding the coordinated movements of these agents. As a result, a critical problem for coordinated control is to design appropriate protocols and algorithms such that the group of agents can reach consensus on the shared information in the presence of limited and unreliable information exchange as well as communication time delays. In multiagent systems, communication time delays between agents are inevitable due to various reasons. For instance, they may be caused by finite signal transmission speeds, traffic congestions, packet losses, and inaccurate sensor measurements. In addition, in practi- cal engineering applications, the agents in multiagent systems transmit sampled information by using sensors or communication network, and the coordination control algorithms are proposed based on the discrete time sampled data to achieve the whole control object. The typical discrete-time consensus control strategy was provided by Jadbabaie et al. 1, which is a simplified Vicsek model 2. Recently, the consensus analysis of the discrete time