  Swarm robotic systems are systems in which multiple robots having simple
functionality perform tasks through their cooperation, and are advantageous in
that they can exhibit non-trivial macroscopic functions such as adaptability,
fault tolerance, and scalability. We previously proposed a simple model of
swarm formation inspired by friendship formation process in human society, and
demonstrated via simulation that various non-trivial patterns emerge. In this
study, we examine the applicability of the proposed model to a swarm robotic
system. As a first step, we developed five robots and demonstrated via
real-world experiments that the simulation results can be largely reproduced.
