Augmenting the acoustic piano with electromagnetic string actuation and continuous key position sensing

This paper presents the magnetic resonator piano, an aug-mented instrument enhancing the capabilities of the acous-tic grand piano. Electromagnetic actuators induce the strings to vibration, allowing each note to be continuously con-trolled in amplitude, frequency, and timbre without exter-nal loudspeakers. Feedback from a single pickup on the piano soundboard allows the actuator waveforms to remain locked in phase with the natural motion of each string. We also present an augmented piano keyboard which reports the continuous position of every key. Time and spatial res-olution are sufficient to capture detailed data about key press, release, pretouch, aftertouch, and other extended ges-tures. The system, which is designed with cost and setup constraints in mind, seeks to give pianists continuous con-trol over the musical sound of their instrument. The in-strument has been used in concert performances, with the electronically-actuated sounds blending with acoustic in-struments naturally and without amplification