Monitoring the evolution of clouds with UAVs

Abstract

We study the problem of monitoring the evolution of atmospheric variables within low-altitude cumulus clouds with a fleet of Unmanned Aerial Vehicles (UAVs). To tackle this challenge, two main problems can be identified: i) creating on-line maps of the relevant variables, based on sparse local measurements; ii) designing a planning algorithm which exploits the obtained map to generate trajectories that optimize the adaptive data sampling process, minimizing the uncertainty in the map, while steering the vehicles within the air flows to generate energetic-efficient flights. Our approach is based on Gaussian Processes (GP) for the mapping, combined with a stochastic optimization scheme for the trajectories generation. The system is tested in simulations carried out using a realistic three-dimensional current field. Results for a single UAV as well as for a fleet of multiple UAVs, sharing information to cooperatively achieve the mission, are provided.

Guidance algorithm for smooth trajectory tracking of a fixed wing UAV flying in wind flows

“…that only depends onṗ and p. Proof: By direct inspection of (14) it is clear that it only depends onṗ and p. Consider that p ∈ G withṗ d as in (7). Then in order to keep G invariant we have to satisfy the right hand side of (9) for the time derivative ofp.…”

“…Then in order to keep G invariant we have to satisfy the right hand side of (9) for the time derivative ofp. The angular velocity (14) is the substitution of (10) and (9) into (13), which determines the course heading rateχ in order to keep G invariant. Remark 3.3: Notice that the yaw rateψ and the course heading rateχ are different concepts and quantities.…”

“…This last feature is desirable for certain practical problems. For example, for the sampling of the atmosphere by UAVs [14] one can model the boundary of travelling clouds by a 3D slowly changing paraboloid parallel to the ground. The desired trajectory for studying the surroundings of such a cloud can be given by the intersection of a plane with this paraboloid.…”

Guiding vector field algorithm for a moving path following problem

“…Many applications, however, require to use more sophisticated curves than combinations of straight lines and circles. Such tasks include atmospheric monitoring by UAVs (Renzaglia et al, 2016) and the ocean sampling by underwater gliders (Paley et al, 2008). In particular, for the problem of the cloud monitoring (Renzaglia et al, 2016) the desired path can be obtained by enclosing the shape of the cloud by a smooth curve.…”

“…Such tasks include atmospheric monitoring by UAVs (Renzaglia et al, 2016) and the ocean sampling by underwater gliders (Paley et al, 2008). In particular, for the problem of the cloud monitoring (Renzaglia et al, 2016) the desired path can be obtained by enclosing the shape of the cloud by a smooth curve. However, to perform this task successfully, one has to take into account a drift of the cloud due to the influence of the wind.…”