Swarm Relays: Distributed Self-Healing Ground-and-Air Connectivity Chains

The coordination of robot swarms - large decentralized teams of robots -generally relies on robust and efficient inter-robot communication. Maintainingcommunication between robots is particularly challenging in field deployments.Unstructured environments, limited computational resources, low bandwidth, androbot failures all contribute to the complexity of connectivity maintenance. Inthis paper, we propose a novel lightweight algorithm to navigate a group ofrobots in complex environments while maintaining connectivity by building achain of robots. The algorithm is robust to single robot failures and can healbroken communication links. The algorithm works in 3D environments: when aregion is unreachable by wheeled robots, the chain is extended with flyingrobots. We test the performance of the algorithm using up to 100 robots in aphysics-based simulator with three mazes and different robot failure scenarios.We then validate the algorithm with physical platforms: 7 wheeled robots and 6flying ones, in homogeneous and heterogeneous scenarios.