Robotic Clam Digs in Mudflats 

To design a lightweight anchor that can dig itself in to hold small underwater submersibles, Anette (Peko) Hosoi of MIT borrowed techniques from one of nature's best diggers — the razor clam.

"The best anchoring technology out there is an order or magnitude worse than the clam — most are two or three orders worse," says Hosoi, whose group presented this work at the 62nd Annual Meeting of the American Physical Society's (APS) Division of Fluid Dynamics, which took place from November 22-24 at the Minneapolis Convention Center.

Using relatively simple anatomy, the bivalve burrows into the bottom of its native mudflats at a rate of a centimeter per second. Hosoi's studies of the physics behind this remarkable ability have revealed that the digging is accomplished in two motions - a push upwards with its foot, which mixes the grains of solid into the liquid above and a synchronized push down.

By borrowing this principle, Hosoi and graduate student Amos Winter have created a simple robot that is now being tested out in the salt water mudflats off of Cape Cod. It digs just as fast as the living clam and is "small, lightweight and does not use a lot of energy," says Hosoi.

The robot is operated electronically via a tether and is made to open and close via pressured air from a scuba tank.

The presentation, "The design, testing, and performance of RoboClam, a robot inspired by the burrowing mechanisms of Atlantic razor clam (Ensis directus)" by Amos Winter et al of MIT took place on November 22, 2009.