In this paper synchronization of both the orientation and velocity for a group of unicycle robots is studied. It is assumed that a robot can only detect and obtain information from those robots that lie in the proximity (within certain distance). A minimum dwell time is imposed on the updating of neighborhood relation in the controller in order to avoid introducing chattering in the closed-loop system that may be caused by abrupt changes of the relation, which as a consequence implies that the neighbor information will be updated only at discrete time instants in the control. In the paper a distributed feedback control law is designed for each agent, and a sufficient condition for uniformly and independently distributed initial states is provided for reaching the synchronization, which depends on the neighborhood radius, the maximum initial translational velocity and the dwell time.