Abstract
A mobile robot system consists of anonymous mobile robots, each of which autonomously performs sensing, computation, and movement according to a common algorithm, so that the robots collectively achieve a given task. There are two main models of time and activation of the robots. In the semi-synchronous model (SSYNC), the robots share a common notion of time; at each time unit, a subset of the robots is activated, and each performs all three actions (sensing, computation, and movement) in that time unit. In the asynchronous model (ASYNC), there is no common notion of time, the robots are activated at arbitrary times, and the duration of each action is arbitrary but finite. In this paper, we investigate the problem of synchronizing ASNYC robots with limited sensing range, i.e., limited visibility. We first present a sufficient condition for an ASYNC execution of a common algorithm to have a corresponding SSYNC execution of ; our condition imposes timing co