An approach to time- and space-differentiated pattern formation in multi-robot systems

We consider the problem of non-trivial pattern formation in decentralised multi-robot systems, and, in particular, how to achieve timeand space-varying behaviour. To tackle the problem, we explore the idea of evolving the fine-level regulation of an underlying self-organising controller. Results from simulation show the promise of the approach: we demonstrate a robot cluster that can stably maintain two different spatial patterns, switching between the two upon sensing an external signal; we also demonstrate a cluster in which individual robots develop differentiated states despite having identical controllers (which could be used as a starting point for functional specialisation of robots within the cluster). The controller was developed with a particular hardware platform in mind—the underwater HYDRON robots developed by the HYDRA consortium (an EU Fifth Framework project). We discuss the implementation of the controller on this and other multi-robot platforms comprising free-moving individual robots, and suggest possible simplifications of the design. This work could eventually have applications in various situations that require robust, complex self-organising behaviour in a collection of free-moving robots, e.g. in space, underwater and nano-scale systems.