Stable formation of groups of robots via synchronization

In this paper, we consider a problem of formation control for two teams of robots. Synchronization inside each team, intra-group, and between the two teams, inter-group, are important in applications where robots belonging to different teams need to coordinate to perform a given task. We are motivated by the work reported in [1] in which a group of planar agents is driven into a special case of phase balancing known as splay state, i.e., a circular formation with equally spaced phases among the robots in the team. In this paper, we are interested in achieving not only splay state but also phase alignment between the agents in the two groups. We formally analyze the stability of the desired intra-group and inter-group phase configuration state. Simulation and experimental results employing a team of terrestrial robots and a team of rotorcraft aerial platforms verify the validity of the proposed coordination strategy.