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Foundations of Robotics Seminar, November 10, 2010
Time
and Place | Seminar Abstract
Razor Clam to RoboClam: Burrowing Drag Reduction Mechanisms and their Robotic Adaptation
Amos Winter
SUTD-MIT International Design Center
MIT
NSH 1507
Talk 4:00 pm
The Atlantic razor clam (Ensis directus) is one of nature's most adept subsea burrowing organisms, able to dig at nearly 1cm/s and travel over a half kilometer on the energy in a AA battery. We discovered that Ensis achieves such phenomenal digging performance by using motions of its shell to locally fluidize surrounding substrate. Moving through fluidized, rather than static, soil reduces drag forces on Ensis to a level within the animal’s strength capabilities and results in burrowing energy that scales linearly with depth, rather than depth squared. Theoretical derivations of the soil/fluid/solid mechanics at play during localized fluidization, as well as experimental results, demonstrate that the size and properties of the fluidized zone around Ensis can be predicted using two commonly measured geotechnical parameters: coefficient of lateral earth pressure and friction angle. Burrowing drag reduction has potential value to industrial applications such as anchoring, oil recover, and subsea cable installation. We constructed RoboClam, a robot that digs using the same mechanisms as Ensis, to explore the viability of localized fluidization burrowing as a new technology. Burrowing data show the machine is able to match the energetic savings of the animal and achieve localized fluidization in both granular and cohesive substrates.
The Robotics Institute is part of the School of Computer Science, Carnegie Mellon University.