High-jumping robot

Nature is often the inspiration behind mechanical technology designed to perform complex physical tasks, like trying to fly like a ladybug or run like a cheetah. However, when it comes to making robots jump, a team of engineers decided to ignore biological constraints, allowing them to build a prototype that breaks all the high-jump records.

In the animal kingdom, the best jumper is probably the meadow froghopper Philaenus spumarius. This insect belongs in the spittlebug group, is only about 6mm long and makes a home out of foamy urine. It also can jump as high as 700mm, more than 100 times its body length, at a take-off velocity of four metres per second (m/s).

Researchers at the University of California, Santa Barbara, have just smashed all animal and robotic jumping records, with a robot that is 30cm tall that can jump over 30 metres high. This is 50 times higher than the froghopper, with a take-off velocity of 28 m/s. Details of their construction and testing have been published in Nature.

Like the froghopper’s legs, the robot design uses elastic potential, where energy is stored in a contracted spring device called the actuator, which is suddenly released and causes propulsion. For animals though, the muscles of a leg can only contract once. The robot design defies these biological limits by using a motor which turns multiple times before each jump, storing multiple contractions of energy in its spring.

The trajectory of the jumping robot, with
lines marked at every 200 milliseconds.
The human is 1.83m for scale.
Credit: Elliot W Hawkes

It also cleverly uses lightweight materials; its total weight is just 30 grams, with the heaviest part the 10g motorised spring. An orca, or killer whale (Orcinus orca) weighing four tonnes uses about 200 joules per kilogram of energy to leap out of the water. With its light weight and motorised spring actuator, the robot leaps with the staggering energy of 7000 joules per kilogram.

Why is having a jumping robot important? Using this technology, this robot can survey environments that are challenging for wheeled, walking or even flying designs.

Associate Professor Elliot Hawkes, lead author on this collaboration, is working with NASA to develop this high jumper for space exploration. “On the moon, our device could theoretically jump forward half of a kilometre while going 125 metres high in a single leap,” says Hawkes. “For instance, it could hop onto the side of an inaccessible cliff or leap into the bottom of a crater, take samples and return to a wheeled rover.”

This work is still in development, with the current prototype not yet having the navigational abilities and control required for the applications Hawkes describes. Nevertheless, the nascent technology is definitely one impressive jump towards a giant leap for humankind.

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