Mechanics and Bio-Inspired Robotics of Fish Locomotion

Knifefish are highly maneuverable swimmers capable of navigating complex environments. The fish generate thrust by undulating an elongated ventral fin. We study the fin mechanics using motion capture of live fish, computational fluid dynamics, and bio-inspired robotics. Using these tools, we are uncovering the underlying principles of knifefish locomotion which can then be implemented into underwater robotics to enhance maneuverability.

Forward and backward traveling waves along the ribbon fin of the black ghost electric knifefish.

The knifefish inspired GhostBot. We've built one of the most advanced fish robots in the world, with 34 degrees of freedom (the humanoid robot ASIMO has 26; the Roomba floor vacuum robot has 2), in order to better understand knifefish mechanics and sensorimotor coupling. This video is the first where we discovered that inward counter-propagating waves generate a strong downward jet, producing vertical thrust. This is a key element of knifefish maneuverability. The water is seeded with reflective particles for subsequent particle imaging velocimetry. 

In this video, Ghostbot demonstrates 'nodal point control' in which a closed-loop positioning algorithm shifts the point at which inward counter-propagating waves meet in order to control position. 

We perform 3D Navier-Stokes simulations of fish and robot locomotion. Shown here is forward swimming followed by a rapid reversal, similar to what we discovered the real fish uses for hunting prey.

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