Design of a Precision Linear-Rotary Positioning Actuator
Wei Gao, Shinji Sato, Yasumasa Sakurai, and Satoshi Kiyono
Nanosystems Engineering Laboratory, Department of Nanomechanics, Tohoku University, 6-6-01 Aramaki Aza Aoba, Sendai 980-8579, Japan
We designed a prototype linear-rotary (Z-θ) dual-axis actuator for precision positioning in which an aluminum rotor (moving element) moves along and rotates around the axis (Z) of a ceramic cylinder (drive rod). The Z-θ actuator consists of a Z-piezoelectric actuator (Z-PZT) (maximum stroke: 12µm) for linear Z-motion, two θ-piezoelectric actuators (θ-PZTs) (maximum stroke: 9.1µm) for rotational θ-motion, a drive rod, and a rotor. θ-PZTs are attached to the drive rod via a clamp. The rotor’s inner side contacts the drive rod with a certain friction. Z-axis positioning uses a smooth impact drive to achieve a long stroke by applying periodic saw-toothed voltage to the Z-PZT. Sinusoidal voltage is applied to θ-PZTs for rotary positioning, not based on a smooth impact drive. The prototype actuator stroke along the Z-axis, limited by the drive rod length, is 10mm and rotary motion is unrestricted. Positioning resolution is a few nanometers and maximum speed in the Z-direction is approximately 2.4mm/s. The maximum revolution speed is 50rpm.
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