Self-Organization of a Robot Swarm into Concentric Shapes

In this paper, we show how a swarm of differential-drive robots can self-organize into multiple nested layers of a given shape. A key component of our work is the reliance on inter-robot collisions to provide information on how the formation should grow. We describe a simple controller and experimentally evaluate how its performance scales as the number of robots in the swarm increases from tens to several hundred robots. The average quality of the formation is shown to be a linearly decreasing function of swarm size, although the steepness of this line depends on the complexity of the formation. We also show that the time for a swarm to form a given shape does not grow quickly even as the number of robots in the swarm increases by a large amount.