Decentralized local-global connectivity maintenance for networked robotic teams

A prerequisite for a team of robots to cooperate is to maintain connectivity among robots. Connectivity maintenance has been extensively studied recently and several local and global connectivity maintenance algorithms have been proposed for the distance dependent communication topology. Local methods are known to be very restrictive and it will be shown that global methods, based on power iteration estimation, could be sluggish in the presence of communication delay and non-converging in large and sparse robot teams. Therefore, a method based on k-hop routing is proposed, where k is a design parameter to determine the locality level of the proposed method. Before any link disconnection, a test for an alternative k-hop path is executed and, based on its result, the disconnection is allowed or blocked. Blocking displacement for maintaining connectivity will eventually immobilize (freeze) the network. Therefore, a procedure for unfreezing the network is also proposed. Simulation results are provided to further investigate the proposed method.