Development of Spatially Seamless Local Communication System Based on Time Sharing Communication Strategy

For multiple robots to achieve complex tasks while cooperating autonomously, communication among those robots is indispensable. We have developed a local communication system, LOCISS, which uses infrared light as a medium to prevent the convergence of communication by restricting the communication area. In this system, eight pairs of transmitting and receiving elements are located all around a robot, surrounding it for communication. It is also possible for each element to transmit individual information. However, because of imperfections in their directivity, communication gaps exist between elements, preventing sequences of communication. As described in this paper, SS-LOCISS makes a robot's surroundings spatially seamless in terms of communication by rotating transmitter and receiver. First, a method is given for restoring pulses that have an incomplete shape because of transmitter and receiver rotations. Next, restrictions that are needed for all pulses transmitted to be received are considered, and characteristics of communication strategies derived from the restrictions are verified. After that, areas of transmission and reception are defined, and transmitter and receiver structures that might allow for the exchange of individual information in every area are considered. A method of signal coding is also proposed, one that may eliminate inconsistencies occurring at the dividing lines between transmission areas due to transmitter and receiver rotations. Then, SS-LOCISS prototypes demonstrate its communication accuracy and consistency on these dividing lines. Finally, we consider ways to improve its transmission rate so that SS-LOCISS may be applied to systems.