Streamwise and lateral maneuvers of a fish-inspired hydrofoil

Fish are highly maneuverable compared to human-made underwater vehicles. Maneuvers are inherently
transient, so they are often studied via observations of fish and fish-like robots, where their
dynamics cannot be recorded directly. To study maneuvers in isolation, we designed a new kind of
wireless carriage whose air bushings allow a hydrofoil to maneuver semi-autonomously in a water
channel. We show that modulating the hydrofoil's frequency, amplitude, pitch bias, and stroke speed
ratio (pitching speed of left vs right stroke) produces streamwise and lateral maneuvers with mixed
effectiveness. Modulating pitch bias, for example, produces quasi-steady lateral maneuvers with
classic reverse von K ármán wakes, whereas modulating the stroke speed ratio produces sudden yaw
torques and vortex pairs like those observed behind turning zebrafish. Our findings provide a new
framework for considering in-plane maneuvers and streamwise/lateral trajectory corrections in fish
and fish-inspired...

Source: Bioinspiration and Biomimetics - August 24, 2021 Category: Science Authors: Qiang Zhong and Daniel B Quinn Source Type: research