Multi-robot coverage to locate fixed targets using formation structures

Abstract: This paper develops an algorithm that guides a multi-robot system in an unknown environment in search of fixed targets. The area to be scanned contains an unknown number of convex obstacles of unknown size and shape. The algorithm covers the entire free space in a sweeping fashion and as such relies on the use of robot formations. The geometry of the robot group is a lateral line formation, which is allowed to split and rejoin when passing obstacles. It is our main goal to exploit this formation structure in order to reduce robot resources to a minimum. Each robot has a limited and finite amount of memory available. No information of the topography is recorded. Communication between two robots is only possible up to a maximum inter-robot distance, and if the line-of-sight between both robots is not obstructed. Broadcasting capabilities and indirect communication are not allowed. Supervisory control is prohibited. The number of robots equipped with GPS is kept as small as possible. Applications of the algorithm are mine field clearance, search-and-rescue missions, and intercept missions. Simulations are included and made available on the internet, demonstrating the flexibility of the algorithm.