Scalable multi-radio communication in modular robots

• We present a multi-radio architecture for communication in modular robots.
• Our architecture guarantees constant bandwidth neighbor-to-neighbor communication.
• We prove our architecture scales to infinitely large networks 2D and 3D networks.
• The architecture is validated using a 45-radio testbed with real data loads.
• Results establish the feasibility of using radios for inter-module communication.

Decentralized control of self-reconfiguring modular robots requires reliable inter-module communication. Communication links must tolerate module misalignment and implement the neighbor-to-neighbor communication model. In this paper, we propose a wireless system based on multiple radios per module that addresses these challenges. Although the capacity of general wireless mesh networks is known to rapidly decrease with network size, we show that a multi-radio single-channel system has constant capacity in square and cubic lattices of infinite size. We validate the performance of such a system in a testbed with 15 unactuated modules using synthetic data and a benchmark decentralized algorithm. We also demonstrate automatic neighbor detection. The main benefits of radio communication in modular robots are tolerance to module misalignment and to eliminate the tight coupling between communication and mechanical design necessitated by typical existing infrared and wired systems. Our results are the first to establish the feasibility of radio as the primary means of inter-module communication in modular robots.