Learning step-level dynamic soaring in shear flow
For researchers in bio-inspired flight and autonomous systems, this work shows that efficient energy-harvesting flight can emerge from local interactions with flow, eliminating the need for explicit planning in unsteady environments.
This work demonstrates that dynamic soaring can emerge from step-level, state-feedback control using deep reinforcement learning, without explicit trajectory planning. The learned policy achieves robust omnidirectional navigation across diverse shear-flow conditions, generalizes across varying conditions, and reproduces key features of biological flight and optimal-control solutions.
Dynamic soaring enables sustained flight by extracting energy from wind shear, yet it is commonly understood as a cycle-level maneuver that assumes stable flow conditions. In realistic unsteady environments, however, such assumptions are often violated, raising the question of whether explicit cycle-level planning is necessary. Here, we show that dynamic soaring can emerge from step-level, state-feedback control using only local sensing, without explicit trajectory planning. Using deep reinforcement learning as a tool, we obtain policies that achieve robust omnidirectional navigation across diverse shear-flow conditions. The learned behavior organizes into a structured control law that coordinates turning and vertical motion, giving rise to a two-phase strategy governed by a trade-off between energy extraction and directional progress. The resulting policy generalizes across varying conditions and reproduces key features observed in biological flight and optimal-control solutions. These findings identify a feedback-based control structure underlying dynamic soaring, demonstrating that efficient energy-harvesting flight can emerge from local interactions with the flow without explicit planning, and providing insights for biological flight and autonomous systems in complex, flow-coupled environments.