SO(2)-Equivariant Downwash Models for Close Proximity Flight

Multirotors flying in close proximity induce aero- dynamic wake effects on each other through propeller down- wash. Conventional methods have fallen short of providing adequate 3D force-based models that can be incorporated into robust control paradigms for deploying dense formations. Thus, learning a model for these downwash patterns presents an attractive solution. In this paper, we present a novel learning- based approach for modelling the downwash forces that exploits the latent geometries (i.e. symmetries) present in the problem. We demonstrate that when trained with only 5 minutes of real- world flight data, our geometry-aware model outperforms state- of-the-art baseline models trained with more than 15 minutes of data. In dense real-world flights with two vehicles, deploying our model online improves 3D trajectory tracking by nearly 36 % on average (and vertical tracking by 56 %).