Passivity allows robot to reproduce several styles

Experienced piano players will tell you it takes years to master the art. Scientists at the University of Cambridge have 3D printed a robotic hand that plays a number of styles without even moving its fingers. It’s all in the wrist. Using passivity, the fingers apply pressure on the keys based on how they’re positioned and the stiffness of its joints. And since it’s Christmas, yes, the hand plays “Jingle Bells.”

The passivity allows the hand to be simpler and more energy efficient than if each finger moved. Instead, the robotic wrist and arm move, while 3D printed soft materials make up the fingers and more rigid material takes the place of knuckles.

“We can use passivity to achieve a wide range of movement in robots: walking, swimming or flying, for example,” Josie Hughes, lead author of the study in Science, said. “Smart mechanical design enables us to achieve the maximum range of movement with minimal control costs: we wanted to see just how much movement we could get with mechanics alone.

“Piano playing is an ideal test for these passive systems, as it’s a complex and nuanced challenge requiring a significant range of behaviours in order to achieve different playing styles.”

Soft components are relatively new to robotics, thanks to 3D printing. Making robots as flexible as humans, especially in such complex areas as the hands, is a difficult proposition. The passivity method allows robotic hands to perform a variety of tasks.

“This approach allowed the printing of a passive anthropomorphic hand that provided the ability to reproduce complex human hand capabilities,” the study says, “and to show hand behaviors that cannot be performed by other conventional robots.”

With dexterity such as that exhibited without moving fingers, scientists are a step closer to making robots more lifelike able to perform more complex tasks.