Multi-robot pursuit-evasion without maps

We propose a distributed algorithm enabling a large team of robots to detect all intruders within a large planar environment. Each robot can only detect intruders and communicate with other robots within a limited range. No map of the environment is given, and none is built during the process. Robots are only capable of following walls and other robots that are nearby. The algorithm puts together elementary behaviors giving robots the means to coordinate their movement in order to cover lines between opposite walls with their sensors and discover nearby new walls. A line has leading robots at its endpoints that follow walls and hence move the line of robots forward. Multiple such lines move through the entire assigned area in order to detect all intruders. The movement of multiple lines is coordinated by using a graph representation of the environment that describes possible line movements and their associated costs in terms of robots. This coordination requires only local communication between the leaders of different robot lines when they meet. Finally, we demonstrate how the algorithm can be implemented using elementary wall following and obstacle discovery behaviors.