System design and resource analysis for persistent robotic presence with multiple refueling stations

Despite the capabilities of unmanned aerial vehicles (UAVs), it is not possible to conduct long-term missions with a just few UAVs due to fuel restrictions. This requires a system that includes multiple UAVs and automated recharging stations for an automatic and persistent service. In order to construct a persistent presence system such as local surveillance and monitoring, it is important to determine the design of the mission and the number of resources required. In this paper, a system consisting of multiple target areas and multiple stations is considered. There arc two types of stations: refueling and main stations for maintenance. UAVs can travel further using the refueling stations. A decision-free Petri net model for persistency is developed for cyclic paths including multiple immobile targets and stations. From the Petri net model, we derive a closed-form function for the minimum number of resources in the persistent system. A mathematical model that has the objective function derived from the Petri net is developed. To resolve the computational issue, a genetic algorithm (GA) is used to solve the problem. As the result, the minimum number of resources required and the mission path are derived.