ul 2 00 4 Multi - agent coordination using nearest neighbor rules : a revisit to Vicsek model ∗

Recently Jadbabaie, Lin and Morse (IEEE Transactions on Automatic Control, 48(6):988-1001, 2003.) give a mathematical analysis for the discrete time model of groups of mobile autonomous agents raised by Vicsek et al. in 1995. In their paper, Jadbabaie et al. show that all agents shall move in the same heading provided that these agents are periodically linked together. This paper sharpens this result by showing that coordination will be reached under very mild condition. This also gives an affirmative answer to one question raised by Jadbabie et al.