Design and performance of a piezoelectric actuated precise rotary positioner

The need for nanometer resolution positioning technique draws significant attention for semi-conductor industry, biotechnology, and nanotechnology. This paper presents a design of friction-drive rotary stage driven by piezoelectric (PZT) actuator. This stage includes a multiplayer PZT actuator, Scott Russel mechanism, an actuation stage, a pre-load spring and an output shaft. The rotary positioning in this paper is accomplished by the stick-slip effect which a piezoelectric generated force is applied to produce an opposite angular momentums of the rotor to overcome the static friction and to achieve a relative motion. The optimum performance of the stage was achieved by adjusting the pre-load of a spring. Finite element analysis and Taguchi optimization method were extensively conducted to analyze the displacement, stress and vibration behavior for optimum design. Using the wire electro-discharge-machining (EDM), the rotary stage was fabricated and its performance was evaluated. The stage reaches the resolution of 0.13 rad and speed of 0.15 degrees per hour. The rotary positioner can be used in wafer fabrication and SEM for nano-manipulation.