Meet Salto, a one-legged robot that jumps off walls with the ease of a Parkour athlete. Such agility could prove crucial in disaster scenarios, where searching for survivors or inspecting damage can require navigating uneven terrain.

Salto is not the highest-jumping robot ever. But the springs in earlier machines typically took a while to reload. Salto, by contrast, can re-load in just 120 milliseconds, fast enough to produce multiple jumps in a row, and in particular to reach higher by stepping on a wall – a trick also deployed in Parkour.

“When it’s contacting the wall, the motor pumps more energy into the system,” says Duncan Haldane, a mechanical engineer at the University of California at Berkeley. “It’s not just bouncing off the wall.”

To create Salto, Haldane and his collaborators took inspiration from one of nature’s best jumpers, the galago (Galago senegalensis), a small African primate. Before taking a leap, galagos crouch to load energy in their stretched tendons. When they spring they get 15 times more acceleration than if they used muscle force alone. Salto emulates that biomechanical feat thanks to the latex spring between the robot’s motor and its leg.

The robot, whose name comes from the Latin verb saltare which means ‘to jump’, stands about 30 centimeters tall with its thin legs stretched out – and can jump to a maximum height of one metre in a single leap. So far it can only do two jumps in a row because it lacks the ability to stabilize itself in three dimensions, but Haldane says that future versions will fix that.

Practical applications are farther off, and a useful machine would probably need two legs to walk as well as jump, say the researchers. Haldane’s team publishes its results on 6 December in Science Robotics1.

Credit: Duncan Haldane