An inertial piezoelectric rotary actuator characterized by the motion without rollback

Rollback happens to most inertial piezoelectric actuators due to the forward and backward bending of bimorphs in a driving cycle. An inertial piezoelectric rotary actuator with two asymmetrically clamped bimorphs working in phase is proposed in this study to eliminate rollback. The electrical in-phase connection of the two bimorphs gives the actuator two steps in a driving cycle but a reduced load capacity. Comsol software is used for modal analysis and a series of experiments were carried out to study the output performance of the actuator. Experiment results indicated that the actuator can work stably at two steps per cycle without rollback in all working conditions. The minimum angular displacement was 7.4 μrad under the signal of 15 V, 1 Hz without load. With the application of a bias unit, the actuator can drive a 460 g load which is comparable with other inertial piezoelectric actuators. In a word, the in-phase connection of two asymmetrically clamped bimorphs can eliminate rollback, which provides a new idea for the research of precise actuators without rollback. (paper)