Low Altitude Strategic and Pre-Tactical Planning Services for UAM
Flavia Causa, Giancarmine Fasano · 2025
This paper proposes a planning pipeline able to define offline trajectories for a high traffic density requesting to access the very low level (up to 120 m above ground level) urban airspace in a reference time interval. The planner is composed of two phases, i.e., strategic and pre-tactical. The first step is aimed at defining for each UAV a trajectory which is aware of several constraints of the urban environment including weather, GNSS coverage, fixed obstacles and no-fly zones, landing sites’ locations and ground risk maps. A multi-objective optimization function is developed based on BIT* algorithm. On the other hand, traffic information (which can be very coarse in strategic phase) is only taken into account in pre-tactical step, which is aimed at modifying the strategic path sorting the trajectory using the reasonable-time-to-act concept, which allows overcoming the first-come first-served mechanism. Indeed, reasonable-time-to-act represents the time instant at which the pre-tactical phase must be executed for each UAV which is obtained by going back in time from the required time to start the mission with a time interval which depends on mission’s priority. The offline planner pipeline is developed to be able to deal with several type of missions (and thus planning inputs) and provides at this stage the ability to solve inspection missions, delivery missions (starting from either the same point or different points of the environment) and priority missions. The planner is tested in simulation using a scenario taken from real world and belonging to the city of Naples, Italy. 404 UAVs were assumed to request to access the environment (with 4.1x4.5km2 extension) in 1 hour time interval. Performances of the planning algorithm are assessed by varying the safety margins assumed for collision check and the duration of the reference time interval. Results demonstrate the planner is able to accommodate all the requests within the selected time interval, occupying at maximum 3.7% of the available airspace when safety margins are modified. Conversely reducing the reference time interval while keeping the same number of requests causes severe mission postponing which makes unfeasible several missions.