Georgia Institute of Technology researchers have built a wearable robotic limb that allows drummers to play with three arms. The two-foot long “smart arm” can be attached to a musician’s shoulder. It responds to human gestures and the music it hears. When the drummer moves to play the high hat cymbal, for example, the robotic arm maneuvers to play the ride cymbal. When the drummer switches to the snare, the mechanical arm shifts to the tom. via gizmodo