Clams don’t normally seem like the most active of creatures. Mostly, we know them for being reticent (also tasty when murdered and fried). But clams are actually some of the most wildly efficient, single-minded diggers on the planet. And they’re so good at what they do, in fact, that MIT researchers have developed a robotic version. Yes, folks, it’s the RoboClam.
If you’re wondering why on earth scientists would roboticize cigar-shaped razor clams, first consider the problem of digging underwater. In order to lay underwater cables, like the powerful fiber optic lines that help us communicate all over the world, boats can drag devices behind them that plant the cables in the sea. But shallower waters require human labor. “You literally send down a diver with a shovel,” MIT professor Peko Hosoi says.
Digging on land is one thing, but expending energy while attached to an oxygen tank can be particularly tricky. The challenge with machines, too, is efficiency. If you send down robots carried by autonomous underwater vehicles (AUVs), they have to be exceptionally small and light.
Clams, however, can dig roughly a third of a mile on the energy equivalent of a AA battery. So MIT assistant professor Amos Winter, then a student, decided to get his clam digging license (yes, you need one in Massachusetts) and study how they move.
It turns out that clams can drill so quickly through packed sand because they create a channel of watery quicksand around them. By opening their shells while pointed downwards, they shoot out the “foot” (the slimy, muscly part we eat), then close the shells, forcing water to blow up the foot like a balloon. That foot then tugs the narrower, closed shell down through a little tunnel of liquid space the clam just created for itself. Think of Pac Man chomping into a wall of sand and gliding through a slushy tunnel.
RoboClam pulls off the same maneuver without the “foot.” It simply relies on an actuator motor running on compressed air at its hinge. But when it comes to energy storage, Hosoi imagines that RoboClams could work in pairs to bury a cable while being powered by it at the same time. Think of an electric clothesline with hundreds of little nipping clam clothespins attached. This way, Hosoi notes, they wouldn’t have to carry around a power source.
“You don’t need to build a battery that it needs to carry around,” Hoisoi explains. “Whereas a robot like Big Dog, it would have to carry its power source with it.”
RoboClams could even dig up anchors or, one day, detect sea mines, like those planted around coastlines during World War II.