Autonomous planning and replanning of a single Unmanned Aerial Vehicle: strategies and simulations

The aim of this paper is to define and elaborate the main features of an Unmanned Aerial System (UAS) in order to make it as autonomous as possible. In this context, the authors would propose and verify possible strategies for an autonomous replanning of a route in case out-of-nominal situations would happen. In the first part of the paper, a general methodology to perform an autonomous replanning is proposed, with a particular attention to the techniques already proposed and studied by other research teams [1, 2]. This activity can be seen as a preliminary study to create an algorithm able to propose alternative routes in case replanning actions would be required. In this context, it was necessary to define how many and what kind of critical conditions the UAS has to recognize and correct autonomously. All these critical conditions were separated in different scenarios. With the aim of studying the replanning algorithms for each scenario, the earlier phase of this work leads with the definition of the logical processes that stand behind them. The most important purpose of this activity is to define the main requirements and all the logical processes required to allow the mission planning and replanning. All these evaluations would be a guideline for the generation of a code able to autonomously propose in real-time replanned routes, like those proposed in literature [3, 4]. The second part of the work deals with the simulations of the possible mission scenarios using a specific software called STK (Systems Tool Kit, previously Satellite Tool Kit). This tool is employed in the simulation of planned and replanned routes, in order to verify the respect of the scenario constraints (e.g. flight within the boundaries of a segregated area) and the aircraft performances. In conclusion, the paper would like to highlight some peculiar aspects of an autonomous replanning in order to enhance the efficiency and efficacy of an Unmanned Aerial System. This is considered as a fundamental step to develop and simulate replanning solutions for a fleet of Unmanned Aerial Vehicles (UAVs).