Study of a Precision Pneumatic Positioning Device Using PZT Dither
Yung-Tien Liu*, Kuo-Ming Chang**, and Huang-Ren Lee*
*Department of Mechanical and Automation Engineering, National Kaohsiung, First University of Science and Technology, 2 Jhuoyue Rd., Nanzih, Kaohsiung 811, Taiwan, R.O.C.
**Department of Mechanical Engineering, National Kaohsiung, University of Applied Sciences, 415 Chien Kung Rd., Sanmin, Kaohsiung 807, Taiwan, R.O.C.
A piezoelectric (PZT) actuator featuring a high frequency response is employed to serve as a highfrequency dither and to compensate for the nonlinear motion characteristic of a pneumatic positioning device. To examine the function of the PZT dither, system identification based on a linear model for describing the positioning device was performed. To obtain the most suitable actuating parameters of the PZT dither, the Taguchi method was employed. Using the optimal parameters, the positioning system implemented by the PID controller was configured. For a target position of 4 mm, position control with a positioning accuracy under 0.1 µm was demonstrated. Compared to the pneumatic positioning device using a traditional controller, the device presented in this study features better positioning ability.
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