On the efficiency of local and global communication in modular robots

As exchange of information is essential to modular robots, deciding between local or global communication is a common design choice. This choice, however, still lacks theoretical support. In this paper we analyse the efficiency of local and global communication in modular robots. To this end, we use parameters to describe the topology of modular robots, develop a probabilistic model of local communication using these parameters and, using a model of global communication from literature, compare the transmission times of local and global communication in different robots. Based on our results, we conclude that global communication is convenient for centralized control approaches and local communication is convenient for distributed control approaches. In addition, we conclude that global is in general convenient for low-connectivity configurations, such as chains, trees or limbs, and that local can be faster than global when communicating between distant modules which are not too far apart. Finally, we discuss the potential of flexible communication topologies, which can provide optimal topologies for many configurations, such as those we can split into bodies and limbs.