Compact stick–slip piezoelectric rotary motor with reduced undesired backward motion

We develop a rotary motor to reduce backward motion in stick–slip with an active clamp mechanism. Backward motion refers to the undesired movement observed when operating a rotary stick–slip motor powered by a piezoelectric actuator under actual conditions, where the rotor rotates in the opposite direction to the intended rotation. This could cause imprecision and inaccurate motion. The conventional stick–slip motor relies on contact with the rotor to induce rotation. The proposed active clamp mechanism adjusts the contact distance with the rotor, ensuring contact is maintained only when the rotor is rotating. This helps reduce backward motion. Additionally, implementing this mechanism using the conventional method requires one stick–slip module for rotation and two inchworm drive modules for clamping. In contrast, the proposed mechanism consists of a single module each for the driving actuator and clamping actuator. A preliminary model with a dimension of 34 × 27 mm was constructed for experimentation. Through the experiments, it was confirmed that the proportion of backward motion relative to the initial movement in one step decreased by approximately 20%. Furthermore, with the reduction in backward motion, the rotational displacement per step was confirmed to improve by about twice, increasing from 17 to 33 millidegrees.