Distributed source localisation with no position information

We consider a group of autonomous communicating sensors, and our objective is to steer the group, with a low information exchange, towards the isotropic source of a diffusion process in steady-state. We suppose the graph describing the communication links between sensors to have a time-invariant ring-topology. Each sensor, which has no position information, takes pointwise measurements of the quantity of interest, and is able to measure the bearing angle with respect to its neighbours. We solve the source-localisation task via a gradient-ascent technique based on a distributed implementation of Poisson integral formula; our approach is based on a twofold control law, which is able to bring and keep the set of sensors on a circular equispaced formation while seeking the source.