Most vertically agile robot ever developed

Researchers have designed a small robot that can leap into the air and then spring off a wall, or perform multiple vertical jumps in a row, resulting in the highest robotic vertical jumping agility ever recorded.

The agility of the robot opens new pathways of locomotion that were not previously attainable, said researchers who hope that one day this robot and other vertically agile robots can be used to jump around rubble in search and rescue missions.

To build the robot, known as Salto (saltatorial locomotion on terrain obstacles), researchers at University of California - Berkeley in the US studied the animal kingdom's most vertically agile creature, the galago, which can jump five times in just four seconds to gain a combined height of 8.5 metres.

The galago has a special ability to store energy in its tendons so that it can jump to heights not achievable by its muscles alone. Salto's robotic vertical jumping agility is 1.75 meters per second (m/s), which is higher than the vertical jumping agility of a bullfrog (1.71 m/s) but short of the vertical jumping agility of the galago (2.24 m/s). The robot with the second highest vertical agility that the team measured is called Minitaur (1.1 m/s).

"Developing a metric to easily measure vertical agility was key to Salto's design because it allowed us to rank animals by their jumping agility and then identify a species for inspiration," said Duncan Haldane, a robotics PhD candidate at UC Berkeley, who led the work.

Salto's design is based on the power modulation used by the galago. Power modulation is an adaptation found in natural systems that increases the peak power available for jumping by storing muscular energy in stretchy tendons.

The galago jumps so well because its tendons are loaded with energy by its muscles when it is in a crouched position. Adapting this process to Salto enabled its high vertical agility, including the wall jump. Inside Salto, a motor drives a spring, which loads via a leg mechanism to create the kind of crouch seen in the galago. By using power modulation, Salto does not need to wind up before a jump.

Salto achieved 78 per cent of the vertical jumping agility of a galago. Because of motor power limits, the best untethered robot before Salto had a vertical jumping agility of only 55 per cent of a galago.

"By combining biologically inspired design principles with improved engineering technology, matching the agile performance of animals may not be that far off," said Professor Ronald Fearing.

Salto weighs 100 grams, is 26 centimetres tall when fully extended, and can jump up to one metre. Salto's maximum jump height was roughly 1.008 meters. The research was published in the journal Science Robotics.