A Distributed Coordination Protocol for the Connectivity Maintenance in a Network of Mobile Units

The coordination of a team made by a set of mobile robots involves several challenges since, given a task to be accomplished by the team, the mobility of each robotic unit is often constrained by several factors. Connectivity is one of the most important factors. Cooperating robots must keep connected for many reasons: to plan a working strategy, to coordinate movements and actions, to re-configure the network in case of unexpected events. This paper describes a fully distributed coordination strategy expressly targeted to the maintenance of the connectivity among mobile robots. The proposed approach is based on the periodic broadcast of state information, which is used to drive the mobility strategies of nodes. The team uses a leader/follower organization, where leaders have to move toward predefined locations to perform the given task, while Followers have to coordinate to maintain the global network connectivity, i.e., the multi-hop connection between leaders. The proposed scheme is analyzed to derive its formal properties, and simulation results are presented to show the protocol behaviour under different working conditions.