What’s the News: Nature invented the wheel a good long time before we did: just look at the crazy antics of the mother-of-pearl moth caterpillar, which, when attacked, springs into an airborne coil in less than 60 milliseconds, spinning and twisting in the air like a snake from a can. Now robotics researchers have build a caterpillar robot that mimics that behavior, providing insight into how caterpillars manage it and suggesting new uses for some types of robots. How the Heck:
The robot, called GoQBot for the Q shape it takes in flight, is a 10-cm tube of soft silicone rubber. It’s what’s called a soft-bodied robot, in contrast to the rigid materials used in most other varieties.
Instead of muscles, the robot has two long shape-memory alloy coils running along the length of its body. Shape-memory alloys are metals that “remember” the first shape they are forged into—you can bend them into another form, but as soon as you heat them, they spring back. These coils behave very similarly to caterpillar muscles.
The researchers gave the robot pulses of electrical current that generated heat, and its memory alloy coils contracted, causing it to spring into the air and spin away at more than half a meter per second, a fantastic speed for such a small robot. It took about 50 milliseconds for it to get started, which the researchers think is because the alloy needs time to heat up.
A caterpillar-like lack of joints is key to coordinating this kind of motion, the researchers found through analysis of the forces involved. Think of a wet towel whip whose motion comes directly from the wrist—if the towel had rigid joints, the motion could not propagate so quickly.
What’s the Context: The research was funded by DARPA, which is interested in using soft-bodied robots modeled on creatures like worms and caterpillars in situations like disaster recovery. Although this robot isn't the most coordinated entity—spinning wildly, even when it gets you far away from where you started, is still spinning wildly—it combines a soft-bodied robot’s ability to crawl through tight spaces with the ability to cover large distances quickly, characteristics that have never come in the same robo-package (soft-bodied or otherwise) before. The Future Holds: A good deal more development—the robot still relies on wires to provide the heat that makes it spring, and trailing wires hardly seem like a good feature for crawling through rubble. But can’t you just see an army of leaping caterpillar 'bots leaping into action after a quake? Reference: Huai-Ti Lin, Gary G Leisk and Barry Trimmer. GoQBot: a caterpillar-inspired soft-bodied rolling robot. Bioinspir. Biomim., 6 026007 doi:10.1088/1748-3182/6/2/026007