A Self-Sensing Haptic Actuator for Tactile Interaction with Physical Modelling Synthesis

The use of transducers to excite physical modelling syn- thesisers with real-world audio signals is a well-established practice within the digital musical instrument design com- munity, yet it is normally presented as a unidirectional pro- cess – energy is transferred into the system from human to instrument. In this paper, a novel approach to tactile interaction with physical modelling synthesis is presented, through the use of a self-sensing vibrotactile transducer. This enables simultaneous collocated sensing and haptic ac- tuation with a single moving coil transducer. A current drive amplifier is used for haptic actuation, using signals de- rived from the physical modelling synthesiser. The varying impedance of the transducer (due to changes in the mechan- ical damping) enables the sensing of force applied upon the device whilst also acting as a pickup to excite the physical model, all with simultaneous haptic actuation. A digital filter equivalent of the transducer’s impedance is used to prevent feedback in the system, allowing simultaneous ex- citation and haptic actuation without self-oscillation.