Dyna m ic O p eration F u n d a m entals
How Fast Can a PiezoActuator Expand? Fast response is one of thecharacteristic features of piezo actuators. A rapid drive voltagechange results in a rapid posi-tion change. This property is especially welcome in dynamic applications such as scanning microscopy, image stabiliza- tion, switching of valves/shut- ters, shock-wave generation, vibration cancellation systems,etc.A piezo actuator can reach itsnominal displacement in approximately 1/3 of the period of the resonant frequency, pro- vided the controller can deliverthe necessary current. If notcompensated by appropriate measures (e.g. notch filter, InputShaping Where: T min = time [s]f =resonant frequency[Hz]] Example: A piezo translatorwith a 10 kHz resonant frequen-cy can reach its nominal dis- placement within 30 µs. ® , see p. 4-33) in the servo-loop, such rapidexpansion will be accompanied by significant overshoot.(Equation 13)Minimum rise time of a piezoactuator (requires an amplifier with sufficient output currentand slew rate). Fig. 24. Response of an undamped, lever-amplified piezo actuator (low resonant frequency) to a rapid drive-voltage change. Thisbehavior can be prevented by intelligent control techniques or position servo-control. © PI 1998-2005. Subject to change w/o notice. Cat 118 05/09.17 4-26