REFORMA: Robust REinFORceMent Learning via Adaptive Adversary for Drones Flying under Disturbances

In this work, we introduce REFORMA, a novel robust reinforcement learning (RL) approach to design controllers for unmanned aerial vehicles (UAVs) robust to unknown disturbances during flights. These disturbances, typically due to wind turbulence, electromagnetic interference, temperature extremes and many other external physical interference, are highly dynamic and difficult to model. REFORMA can perform a real-time online adaptation to these disturbances and generate appropriate velocity actions as countermeasures to stabilize the drone. REFORMA consists of two components: a base policy trained completely in simulation using model-free RL and an adaptation module trained via supervised learning with on-policy datasets. By varying the disturbance strength in an adaptation module, i.e., adopting adaptive adversary, the policy is then able to handle extreme cases when the velocity of the drone is immediately affected by disturbances. Finally, we demonstrate the effectiveness of our method through extensive simulated experiments. To the best of our knowledge, REFORMA is the first robust RL approach that uses adaptive adversaries to tackle uncertain disturbances in drone tasks.