Multi-robot exploration and rendezvous on graphs

We address the problem of arranging a meeting (or rendezvous) between two or more robots in an unknown bounded topological environment, starting at unknown locations, without any communication. The goal is to rendezvous in minimum time such that the robots can share resources for performing any global task. We specifically consider a global exploration task executed by two or more robots. Each robot explores the environment simultaneously, for a specified time, then selects potential rendezvous locations, where it expects to find other robots, and visits them. We propose a ranking criterion for selecting the order in which potential rendezvous locations will be visited. This ranking criterion associates a cost for visiting a rendezvous location and gives an expected reward of finding other agents. We evaluate the time taken to rendezvous by varying a set of conditions including: world size, number of robots, starting location of each robot and the presence of sensor noise. We present simulation results to quantify the effect of the aforementioned factors on the rendezvous time.