Design and analysis of a high speed planar motion inchworm piezoelectric actuator with centrosymmetric configuration

Inchworm piezoelectric actuators have the advantage of large strokes, but most of them usually can only carry out linear motion. Some inchworm piezoelectric actuators, composed of multiple piezoelectric stacks, can realize two-degree-of-freedom motion but still fail to simplify the complex structures and struggle to achieve high output speed without backward motion. Here, we design an inchworm piezoelectric actuator that can carry out planar motion with a compact centrosymmetric structure in which only three piezoelectric stacks are used. The amplification mechanisms based on flexure hinges are designed to increase the clamping force and step displacement. A working principle of single-dual mode is designed to effectively utilize the deformations of the driving units, and two steps in one cycle are realized, which improves the output speed of the proposed actuator. Utilizing its center symmetry structure to switch the direction of motion, which enables plane motion. The parameters of the driving units were optimized by theoretical analyses. Then, the finite element method and experiments were employed for the static and dynamic analyses. Experimental results demonstrated the actuator's capability of point-to-point positioning and tracking a circle within the plane and revealed the maximum speeds of 2085 μm/s along the X-axis and 2407.5 μm/s along the Y-axis without backward motion. Herein, a combination of a simple structure and a good output speed without backward motion is achieved on a planar motion inchworm actuator.