Saturation control of a piezoelectric actuator for fast settling-time performance

This brief studies fast tracking control of piezoelectric (PZT) actuators. Adverse effects associated with the PZT actuators typically include the nonlinear dynamics of hysteresis and saturation and the linear vibrational dynamics. To eliminate the loss of performance due to these effects, we propose a new control scheme for the PZT actuators. It consists of a combined feedforward/feedback compensator for hysteresis and resonance compensation and a nested switching controller (NSC) that optimizes a quadratic performance cost function involving the actuator saturation. The NSC not only can guarantee the system stability in the presence of saturation but also can improve the tracking speed by efficiently allocating the control efforts. The experimental results on an actual PZT nanopositioner show that the new control scheme outperforms the conventional control by more than 12% in settling time within the full PZT operational range and with nanoscale precision