Flow structure decides whether a robot searching for odour should follow the wind

Abstract

Robots searching for odour usually surge upwind on contact, steering by the wind sensed now. In simulated reversing wind this rule collapses, favouring controllers that hold an earlier heading. We show that on our benchmark the collapse came from the simulated anemometer. Reading the nominal wind, wind-following controllers reached the source in at most 3.5% of episodes. Reading the odour-carrying flow, the best reached 90%, ahead of a held heading. The winner then depends on the flow. A held heading won in smooth fields that reverse quickly and lost in a stochastic field. A controller-free measure of the sensed wind ranked a moth-inspired follower's success. On a quadruped in a reversing fan arena, wind-following controllers were pushed away from the source, while a heading held from a source-facing start was not. Benchmarks should state which wind their sensor reads and test more than one flow structure.