This Legless, Pancake-Shaped Robot Is an Impressive Jumper

A leaping robot is challenging to design, but this one can hop six times its body length per second and nearly eight times its height

The robot jumps across a mat. It is clear with a blue ring on its rim and black and silver objects on the inside. In this time lapse, the robot jumps across the mat in a straight line.
The robot moves by redistributing liquid and air in its "body." R. Chen et al., Nature Communications 2021

A pancake-shaped robot is putting jumpers like frogs, kangaroos and rabbits to shame by proving that legs aren't necessary for an impressive leap. The robot—which weighs as much as a raisin and is only 2.5 inches long—can jump six times its body length per second and nearly eight times its height, Sabrina Imbler reports for the New York Times.

In a new study published earlier this month in Nature Communications, a team of engineers details the design of a new, floppy robot that can jump like a stingray, Sarah Wells reports for Inverse.

"Most creatures need feet to jump, but some creatures—such as gall midge larvae—can leap by bending of their bodies, which gave us the inspiration to develop a jumping robot without legs," lead author, Rui Chen, an engineer at Chongqing University, tells Inverse.
Continuous jumping on different substrates

Gall midge larvae are only a tenth of an inch long, but they can launch themselves three inches forward—30 times their body length. They do so by bending their bodies into rings and squeezing fluid toward one end of its body. Then, the accumulation of pressure sends the critter flying, the Times reports.

Similarly, the saucer-shaped robot redistributes fluid in its "body." Within its plastic frame, it has a little bubble of air, a bag of an oil-like liquid and electrodes tethered to it. With an electric zap, the liquid shifts forward; its body follows with the air sac acting like a tail. When it lands, it's ready to launch again in just a few seconds, Inverse reports.

Though this robot is in early stages of development, it could lead to novel improvements in the field of soft robotics. Generally, robots that walk or roll on the ground have a tricky time maneuvering through objects. Jumping robots may be able to navigate through uneven terrain and obstacles better, but designing one is a challenge—robots that store energy can jump infrequently, and robots that can't store energy can't jump high enough. Finding a robot that can do both is a tall ask, the Times reports.

The electrode-powered robot designed by Chen and his team can jump both high and far. It has successfully leaped over obstacles like stacked blocks and gravels, though the researchers note that it has a tough time on smooth surfaces, Inverse reports.

The team will keep working on developing the robot, which they have high hopes for. It could be used to sense environmental conditions, like detecting pollutants in buildings, or be fitted with a tiny camera for search-and-rescue missions to save people in disaster areas. Plus, it'll be cheap—likely only a few dollars per bot, the Times reports.

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