A Haptic Piano Keyboard Based on a Real-Time Multibody Model of the Action

Timmermans, Sébastien [UCL] Fisette, Paul [UCL] Ceulemans, Anne-Emmanuelle [UCL]

To finely control his playing and nuances, the pianist needs an essential sensory information, which is called the touch. The latter results from the dynamics of the piano actions equipping traditional acoustic pianos. Present-day digital instruments are equipped with a certain dynamics, which attempts to imitate that of an acoustic piano, but still results in a reduced touch sensation. A multibody model of the double escapement action equipping modern grand pianos has been developed in our lab to capture its full dynamics faster than real-time, via an efficient multibody symbolic model. In this respect, our research work aims at developing a haptic feedback device for digital keyboards, based on this multibody model which can compute the dynamic force to be transmitted to the key through a linear voice-coil actuator, in a quasi-instantaneous way. The combination of these steps should give the pianist the same force feedback feeling as a traditional piano action does. A proof-of-concept prototype has been built. The current hardware design limits the complexity of the multibody model that can be used to reproduce the touch but those limitations should be lifted soon. For the future of this ongoing project, an important aspect relates to the possibility to tune the action parameters, as a piano maker should do, at the pianists’ convenience and, ultimately, to switch between different types of actions at a glance, on the same keyboard. The synchronization of the "virtual action – string" interactions with a sound model is obviously a perspective to be also investigated.