A Piezoelectric Linear Actuator Controlled by the Reversed-Phase Connection of Two Bimorphs

A linear actuator controlled by the reversed-phase connection of two piezoelectric bimorphs is proposed in this study to solve the problem of drawback in the existing piezoelectric linear actuators. The actuator is driven by one excitation signal, the two piezoelectric bimorphs will always bend in opposite directions by the reversed-phase connection, so the directions of the force output by the two piezoelectric bimorphs are opposite. Because of the length difference of the clamping blocks, the two forces outputted by each bending is different in magnitude, and always have a resultant force in the same direction to make the actuator move forward two steps in one cycle without drawback. A series of experiments were conducted to evaluate the performance of the actuator provided. The starting voltage is 40 <inline-formula> <tex-math notation="LaTeX">$\text{V}_{\mathrm {p-p}}$ </tex-math></inline-formula>, resolution can reach <inline-formula> <tex-math notation="LaTeX">$1.16~\mu \text{m}$ </tex-math></inline-formula> without load. The load capacity of the actuator is 450 g with a 100 <inline-formula> <tex-math notation="LaTeX">$\text{V}_{\mathrm {p-p}}$ </tex-math></inline-formula> voltage, a 2-Hz frequency, and the average step displacement in this case is <inline-formula> <tex-math notation="LaTeX">$0.725~\mu \text{m}$ </tex-math></inline-formula>. The prototype has high linearity and good repeatability. Experiments have proved that the actuator controlled by reversed-phase connection can eliminate drawback in principle, and can move forward two steps in one cycle. The resolution of the prototype by the reversed-phase connection is much higher than the in-phase connection, and it is a new method to improve the driving performance of piezoelectric actuators.