Smart strategies to navigate turbulent odor plumes reorienting to local wind

TL;DR

This paper presents a wind-relative reinforcement learning approach enabling agents to efficiently navigate turbulent odor plumes by using a single internal variable and local wind estimation, improving artificial olfactory search strategies.

Contribution

The study introduces a novel reinforcement learning framework that incorporates wind-relative actions and temporal wind integration, trained and tested in realistic turbulence simulations.

Findings

Learned policies outperform traditional cast-and-surge in mild wind conditions.

Performance peaks at an intermediate wind memory time in isotropic turbulence.

Temporal wind integration is identified as a key resource for navigation in turbulence.

Abstract

Olfactory search in turbulent environments is a sensorimotor challenge solved with remarkable efficiency by many animals, yet replicating this ability in artificial systems remains difficult because detections are intermittent and wind direction fluctuates strongly, rendering standard search strategies unreliable. We introduce a wind-relative reinforcement-learning framework in which an agent navigates a turbulent plume with a single internal variable -- the elapsed time since the last odor detection -- and selects actions relative to a locally estimated wind direction filtered through an exponential memory kernel. Policies are trained and evaluated in direct numerical simulations of turbulence, capturing the multi-scale characteristics of velocity and odor fields in natural environments, both in the presence and absence of a mean wind. In a mild mean wind, the learned policy outperforms cast-and-surge regardless of the wind memory time, yet adapts its movement pattern to wind-estimation quality. In isotropic turbulence, performance peaks at an intermediate wind memory time, identifying temporal wind integration as a regime-dependent resource. Our results highlight the importance of developing and validating olfactory-navigation strategies under realistic turbulent conditions, and offer a compact design principle for minimal robotic olfactory navigation and testable predictions for biological search behavior.