Nowadays, the use of unmanned vehicles for border monitoring is taking over in order to reduce the effort of human operators. This paper addresses the problem of the coastal patrolling by proposing a solution based on unmanned underwater and surface vehicles. The focus of the work is on the design of the routes for the unmanned vehicles so as to optimise the limited mission range of the robotic platforms and to allow the re-visit of sensitive areas. A heuristic approach is proposed to compute the navigation plans: it includes a surface platoon to support the underwater vehicles in localisation and communication. The route-planning problem is cast into multiple travelling salesmen problem and solved by applying different heuristic methods for the patrolling mission and the support mission. The first one exploits simulated annealing, while the second one adopts the tabu search. Some promising results are presented, based on simulation.
Keywords: patrolling, optimisation problem, path planning, underwater vehicles