Engineering a robot that can jump 10 feet high -- without legs

Their device, a silicone rod with a carbon-fiber spine, can leap 10 feet high even though it doesn't have legs. The researchers made it after watching high-speed video of nematodes pinching themselves into odd shapes to fling themselves forward and backward.

The researchers described the soft robot April 23 in Science Robotics. They said their findings could help develop robots capable of jumping across various terrain, at different heights, in multiple directions.

"Nematodes are amazing creatures with bodies thinner than a human hair," said Sunny Kumar, lead coauthor of the paper and a postdoctoral researcher in the School of Chemical and Biomolecular Engineering (ChBE). "They don't have legs but can jump up to 20 times their body length. That's like me laying down and somehow leaping onto a three-story building."

Nematodes, also known as round worms, are among the most abundant creatures on Earth. They live in the environment and within humans, insects, and animals. They can cause illnesses in their host, which sometimes can be beneficial. For instance, farmers and gardeners use nematodes instead of pesticides to kill invasive insects and protect plants.

One way they latch onto their host before entering their bodies is by jumping. Using high-speed cameras, Victor Oretega-Jimenez -- a former Georgia Tech research scientist who's now a faculty member at the University of California, Berkeley -- watched the creatures bend their bodies into different shapes based on where they wanted to go.

To hop backward, nematodes point their head up while tightening the midpoint of their body to create a kink. The shape is similar to a person in a squat position. From there, the worm uses stored energy in its contorted shape to propel backward, end over end, just like a gymnast doing a backflip.

To jump forward, the worm points its head straight and creates a kink on the opposite end of its body, pointed high in the air. The stance is similar to someone preparing for a standing broad jump. But instead of hopping straight, the worm catapults upward.

"Changing their center of mass allows these creatures to control which way they jump. We're not aware of any other organism at this tiny scale that can efficiently leap in both directions at the same height," Kumar said.

And they do it despite nearly tying their bodies into a knot.

"Kinks are typically dealbreakers," said Ishant Tiwari, a ChBE postdoctoral fellow and lead coauthor of the study. "Kinked blood vessels can lead to strokes. Kinked straws are worthless. Kinked hoses cut off water. But a kinked nematode stores energy that is used to propel itself in the air."

After watching their videos, the team created simulations of the jumping nematodes. Then they built soft robots to replicate the leaping worms' behavior, later reinforcing them with carbon fibers to accelerate the jumps

Kumar and Tiwari work in Associate Professor Saad Bhamla's lab. They collaborated on the project with Oretega-Jimenez and researchers at the University of California, Riverside.

The group found that the kinks allow nematodes to store more energy with each jump. They rapidly release it -- in a tenth of a millisecond -- to leap, and they're tough enough to repeat the process multiple times.

The study suggests that engineers could create simple elastic systems made of carbon fiber or other materials that could withstand and exploit kinks to hop across various terrain.

"A jumping robot was recently launched to the moon, and other leaping robots are being created to help with search and rescue missions, where they have to traverse unpredictable terrain and obstacles," Kumar said. "Our lab continues to find interesting ways that creatures use their unique bodies to do interesting things, then build robots to mimic them."