MIT computer scientist Graham Grindlay has designed and built a motorized device to help drummers learn simple and complex patterns. The HAptic GUidance System (HAGUS) can record a series of beats then replay the motion to guide the drummer's hand. The result is improved stick control and timing accuracy. The system includes an acrylic frame holding small servo motor with optical encoder feedback, an electromagnetic clutch, a PID motor controller, and a mounting arm for the drumstick.