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Many of nature’s best jumpers have long limbs and extended joints that help them propel themselves into the air by producing great amounts of kinetic energy in the stroke of a muscle. Many robotic jumpers are designed to work this same way, but researchers at the University of California, Santa Barbara have taken a unique approach to jumping that strays from typical nature-inspired methods. The result is a robot that can jump more than 100 feet high.
Lead author on the study, Elliot W. Hawkes, a mechanical engineer at UC Santa Barbara, said that the team sought to create a jumper that could reach the limits of engineered jumps. Hawkes’ robot takes a step beyond trying to replicate the way that animals jump.
“This difference between energy production in biological versus engineered jumpers means that the two should have very different designs to maximize jump height,” Charles Xiao, a Ph.D. candidate in Hawkes’ lab, said. “Animals should have a small spring — only enough to store the relatively small amount of energy produced by their single muscle stroke — and a large muscle mass. In contrast, engineered jumpers should have as large a spring as possible and a tiny motor.”
To increase the amount of energy the robot could store, the research team used a motor that winds up a line which constricts a tension-compression spring. Hawkes’ team created their own spring with carbon-fiber compression bows to maximize its energy storage per unit mass. The team stretched rubber bands from the center of the mechanism to each bow.
As the motor of the robot spins, the line winds up and constricts the compression bows. As this happens, the bows bend outwards and the rubber bands stretch, gathering kinetic energy. When the release mechanism is unlatched the robot launches into the air with all of the kinetic energy stored in the spring.
The resulting robot more than tripled the current world-record for highest jumping robot, held by Boston Dynamics’ Sand Flea, at just over 32 feet. Sand Flea set the record in 2012, and Boston Dynamics has since retired the project.
While Sand Flea couldn’t reach the heights of the UC Santa Barbara team’s robot, it was equipped with large wheels so it could perform reconnaissance missions. Sand Flea used a piston powered by carbon dioxide to make its jumps over fences and onto buildings.
Hawkes’ team hopes that its robot can help reimagine jumping as a form of machine locomotion. This is a method that has been used before, for example in HayBeeSee’s CropHopper. The CropHopper jumps across fields to monitor crops, identify weeds and insects and watch for signs of disease.
The UC Santa Barbara team specifically saw uses for its robot in space, where it could reach even higher heights.
“We calculated that the device should be able to clear 125 meters in height while jumping half of a kilometer forward on the moon,” Hawkes said. “That would be one giant leap for engineered jumpers.”
The team published their research in Nature.