ABC-Center: Approximate-center election in modular robots

Modular robots are composed of many independent connected modules which are able to achieve common goals through communications. Many distributed algorithms have better performance if the modules that have to communicate with all the others, are placed at the center of the system. In this paper, we propose ABC-Center, an iterative algorithm for electing an approximate-center module in modular robots. ABC-Center uses O(1) space per module and O(kd) time, where k is the number of iterations required to terminate and d the diameter of the system. We evaluated our algorithm both on hardware modular robots and in a simulator for large ensemble of robots. The average expected eccentricity of the module elected by ABC-Center is less than 1.25 blocks off for random systems composed of up to 1000 modules. Furthermore, experiments show that our algorithm terminates after a few iterations. Hence, ABC-Center is scalable and adapted to modular robots with low memory resources.