Dear John,
Thanks for writing this - I'm doing a PhD, researching flexible foil
propulison, so I'm very interested in your robo-turtle. I haven't been
able to open the picture you sent, so I'd be grateful if you could try
sending it again.
Many thanks,
Paul
John Long wrote:
> Dear Biomimeticists:
>
> I thought that some of you might be interested in knowing about a
> biorobotics project that Vassar College and Nekton Research (Durham,
> North Carolina) are conducting. While we are mid-stream in the
> development process, the system is proving to be useful at this stage
> for testing some biological hypotheses about multi-appendage,
> lift-based swimming.
>
> We are interested in why living aquatic tetrapods that swim with
> oscillating fins or flippers -- like sea turtles or sea lions --
> don't use the available hind limbs for propulsion. This is
> intriguing since it appears that extinct marine plesiosaurs may have
> used all four fins in a lift-based manner. Based on research that
> shows that pitching and heaving propulsers downstream from vortex
> sources vary performance drastically by changing phase (see work of
> engineers like Mike Triantafyllou and biologists like George Lauder),
> we predict that hindlimb motion must be appropriately synchronized
> with that of the forelimbs in order to avoid performance degradation.
>
> Our robot is roughly the length of a small adult hawksbill turtle,
> weighing in, dry, at 20 kg (image attached; let me know if it doesn't
> come through and you'd like to see it). While the complete
> development arc will create an autonomous vehicle, at the moment it
> is remotely operated via an ethernet umbilicus.
>
> Each fin is based on Nekton's patented design of a flexible hydrofoil
> oscillating in pitch, and the axes of the four fins are coplanar and
> perpendicular to the vehicle's centerline. This fin arrangement,
> coupled with the motor control software, allows the robo-turtle to
> move independently in five of the principle axes: forward-backward
> translation, dive-surface translation, pitch, roll, and yaw.
>
> Experiments are underway to examine how different patterns and phases
> of fin use impact acceleration and maximum velocity.
>
> -- John
> --
> . . . . . . . . . . . . . . . . . . . . . . .
> . . . . . . .
>
> John H. Long, Jr.
> Professor
>
> P.O. Box 513, Vassar College, Department of Biology,
> 124 Raymond Ave., Poughkeepsie, NY 12604-0513, USA
>
> (845) 437-7305 office * (845) 437-7276 lab * (845) 437-7315 fax
>
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>
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