A Study on Precision Stage with Displacement Magnification Mechanism Using Flexure-Based Levers

This study presents a precision stage driven by a piezoelectric actuator and equipped with a displacement magnification mechanism for the purpose of easy displacement measurement. The displacement magnification mechanism consists of flexible hinges and lever mechanisms. The developed stage is able to provide accurate measurement by virtue of the displacement magnification mechanism, but it is exposed to severe residual vibration. In order to overcome the drawback, this study develops a method for reducing residual vibration by using a simulation model for the stage system that takes into account the dynamics of the system and the hysteretic characteristics of the piezoelectric actuator. The Bouc-Wen model is employed to represent the hysteretic characteristics of the actuator. A comparison between simulation and experiment is made to find the best simulation model for the developed system. Input shaping is applied to eliminate the residual vibration from the stage. An improved input shaper is designed to overcome the ineffectiveness of input shaping due to the hysteresis by using the proposed simulation model. Simulations and experiments prove that the proposed simulation model is very useful to investigate the system and that the proposed stage can provide accurate positioning with small residual vibration.