It's always a little weird when we see a completely novel sort of robot, like a robotic clam, and then in the same week, we see another completely novel sort of robot, like a robotic horseshoe crab, that is somehow closely related: in this case, they're both bioinspired aquatic robots, a very specific category. I mean, that sort of coincidence is weird, right? But it happened. So let's meet these things.
Razor clams are absolutely spectacular at digging. It's what they do. They're tricky about it, though: they've figured out a way to move their shells back and forth to liquify the sand or mud surrounding them, making it much easier to burrow downwards by reducing drag. Researchers at MIT are interested in duplicating this technique to make underwater anchoring (useful for boats, cable deployment, and mines) much more energy efficient.
I found some halfway decent video of RoboClam from back in 2009, and it looks very much the same, if not entirely the same:
It looks like the news here is an upcoming paper in the journal Bioinspiration and Biomimetics that describes what the clam is actually doing, why it works, and how the robot is replicating it:
When the razor clam begins to dig, it first retracts its shell, releasing the stress between its body and the soil around it. This causes the soil to begin collapsing, creating a localized landslide around the animal. As the clam continues to contract, reducing its own volume, it sucks water into this region of failing soil. The water and sand particles mix, creating a fluidized substrate—quicksand.
Via [ MIT ]
I don't have nearly as much information on the robotic horseshoe crab from the University of Maryland, but here's the video:
The resemblance to a real horseshoe crab is uncanny, and I'm sure that's no accident: horseshoe crabs are the product of millions of years of evolution that then appeared to cease, leaving them more or less unchanged for the last half billion years or so. And when evolution says, "yup, we've nailed this one, we're done here," you know that the design has to be pretty well optimized for whatever environment it's in: in the case of the horseshoe crabs, it's shallow ocean waters with soft sandy or muddy bottoms, and entering and exiting surf zones.
RoboCrab is not the fastest robot, nor is it the most graceful, but that's totally okay, because it's very effective in the environment that it's been designed for. And, it's adorable.
[ UMD Robotics ]