Electromechanical tuning of self-sensing piezoelectric transducers

The application of a self-sensing piezoelectric transducer included in a bridge readout network is here investigated taking into account the electromechanical interaction. The parametric uncertainties and the piezoelectric device losses as well as the tolerances of the electric components make the balancing of the bridge difficult to achieve in practice. A loss and uncertainties compensation, based on a real-time software implementation of the bridge reference arm is here presented and validated. The standard electrical and the proposed electromechanical balancing are both theoretically and experimentally compared in the case of a simple beam. The bridge output signal that is proportional to the strain rate is then fed back by means of a sharp phase second order low pass filter which is aimed at increasing the damping of the first bending mode of the beam.