Underwater short range free space optical communication for a robotic swarm

Communication mechanism is a major design concern for a robotic swarm, as robots exchange data frequently in order to achieve a collective behavior. Communication using radio frequency (RF) is common if the swarm is land based, however, if the swarm operates underwater then a different form of communication mechanism is needed. In this paper, we discuss the implementation of a short-range communication mechanism based on free space optics for a swarm of robot operating underwater. In order to optimize the communication throughput, a multi-channel design is adopted, therefore, a robot can broadcast data to its peers simultaneously and this is based on a processor that supports parallel computing. Our experimental results show that using a 50 mW semiconductor laser, a transfer rate of 110 Kbps or higher can be achieved; however, transmission quality depends on the clarity and the conditions of the environment.