Connecting trapped civilians to a wireless ad hoc network of emergency response robots

During a disaster, communications are usually impaired. In order for the rescuers and endangered civilians to communicate, we suggest the use of mobile robots that can act as wireless routers. We describe how they can locate trapped civilians and initiate an ad hoc network connection between them and the rescuers, so that the latter can better assess the situation and plan the rescue operation accordingly. The novel problem that arises is the optimal allocation of these robots so that they connect as many civilians as possible, while maintaining their multi-hop connection with a static wireless sink that represents the group of rescuers. We present a centralised formulation, which stems from a combination of characteristics typically found in assignment and network flow optimisation problems. We consider both exact locations for the civilians and uncertain locations with a probabilistic representation. We also present a distributed heuristic with which the robots start from the location of the sink and move autonomously trying to connect the civilians while maintaining connectivity. We evaluate our distributed heuristics in a building evacuation simulator and compare them with the centralised approach.