Towards amphibious robots: Asymmetric flapping foil motion underwater produces large thrust efficiently
Name
MITSG_09-35.pdf
Size
3.38 MB
Format
Adobe PDF
Checksum (MD5)
91bbe6a953f0b7c137db86fa2803a7be
Author(s)
Licht, Stephen Carl
Wibawa, Martin
Hover, Franz S.
Triantafyllou, Michael S.
Date Issued
2009
Publisher
Massachusetts Institute of Technology. Sea Grant College Program
Series/Report no.
MIT Sea Grant Technical Reports;MITSG 09-35
Abstract
The development of amphibious robots requires actuation that enables them to crawl as well as swim; sea turtles are excellent examples of amphibious functionality, that can serve as the biomimetic model for the development of amphibious robots.
In this paper we have implemented the observed swimming kinematics of Myrtle, a green sea turtle Chelonia Mydas residing in the Giant Ocean Tank of the New England Aquarium, on the 1.5-meter long biomimetic vehicle Finnegan the RoboTurtle. It is shown that these kinematics result in outstanding performance in (a) rapid pitching, and (b) rapid level turning. The turning radius for the rigid hull vehicle is 0.8 body lengths, a remarkable improvement in turning ability for a rigid hull vehicle.
Still Finnegan’s performance lags the live turtle’s performance by about 20%. Careful observations have shown that turtles employ a fin motion in-line with the direction of locomotion; this degree of freedom was not available to the Finnegan fins, as presently designed. Experimental tests on a flapping fin equipped with this third degree of freedom have shown that the in-line motion enhances the fin’s performance.
This hydrodynamic result is doubly beneficial to an amphibious robot, because it allows for further enhancements in the hydrodynamic function of fins, while the in-line motion allows the same fins to be used for crawling on land.
MIT Department
Massachusetts Institute of Technology. Sea Grant College Program
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