  In this paper, we present a directional antenna-based leader-follower robotic
relay system capable of building end-to-end communication in complicated and
dynamically changing environments. The proposed system consists of multiple
networked robots - one is a mobile end node and the others are leaders or
followers acting as radio relays. Every follower uses directional antennas to
relay a communication radio and to estimate the location of the leader robot as
a sensory device.
  For bearing estimation, we employ a weight centroid algorithm (WCA) and
present a theoretical analysis of the use of WCA for this work. Using a robotic
convoy method, we develop online, distributed control strategies that satisfy
the scalability requirements of robotic network systems and enable cooperating
robots to work independently. The performance of the proposed system is
evaluated by conducting extensive real-world experiments that successfully
build actual communication between two end nodes.
