Zippy new jumping bot catches air again and again

Meet the robot that can do parkour.

Salto, a lightweight bot that stands on one skinny leg like a flamingo, can leap from floor to wall, then off again — like parkour athletes bouncing between buildings, researchers from the University of California, Berkeley report December 6 in Science Robotics.

Salto’s not the highest jumping robot out there, but it’s got something others lack: speed. The new bot can spring a meter off the ground in just 0.58 seconds — about what a bullfrog can do, study coauthor Duncan Haldane said in a news conference December 5.
The robot’s mix of air and speed could one day aid search-and-rescue teams, he said. Ideally, a rescue robot would be able to move quickly and nimbly over rubble (SN: 12/13/14, p. 16). To do that, Haldane said, “it has to be able to jump.”

For now, Salto is “great eye candy,” says roboticist Jeff Duperret of the University of Pennsylvania. The study’s authors “came up with a new idea and showed it really clearly,” he says.
Haldane’s bot was inspired by a tiny, saucer-eyed primate called the lesser galago (also known as a bush baby). “Animals can outclass any robot when it comes to jumping,” Haldane said. Galagos, in particular, stand out: They’ve got the highest known vertical jumping agility — the ratio of maximum jumping height to the time it takes to complete a jump.
Galagos hunker down in a kind of “supercrouch” that lets them access more energy for jumping, Haldane said. That gives them the ability “to jump high and do it quickly.” His team built this capability into Salto’s leg, a spindly series of eight carbon fiber bars connected with aluminum pins. In the robot’s body, between the leg and the motor, the team attached a kind of spring that’s like a twisted rubber band. When the team turns the motor on, the spring twists, storing energy.
As the bot settles into a deeper and deeper crouch, the motor has more time to twist the spring, Haldane said. And that gives Salto extra oomph when it finally jumps and the spring untwists. It’s like the robot is getting a mega boost, Duperret says. The robot crouches again as it lands, and then can immediately take off for another jump.

That’s an added bonus, said study coauthor Justin Yim. “The spring can store some of the energy of landing for use in the next jump.” It’s like a bouncing ball, he said.

Salto, a palm-sized machine that weighs just 100 grams — about as much as two large eggs — joins a growing list of robots that hop off walls, spring off water or even launch themselves into the air with an explosion (SN: 11/1/14, p.11).