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Proceedings Paper

Design of decoupled dual servo stage with voice coil motor and linear motor for XY long stroke ultra-precision scanning system
Author(s): Ki-Hyun Kim; Young-Man Choi; Dae-Gab Gweon; Dong-Pyo Hong; Koung-Suk Kim; Suk-Won Lee; Moon-Gu Lee
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Paper Abstract

A decoupled dual servo (DDS) stage for ultra-precision scanning system is introduced in this paper. The proposed DDS consists of a 3 axis fine stage for handling and carrying workpieces and a XY coarse stage. Especially, the DDS uses three voice coil motors (VCM) as a planar actuation system of the fine stage to reduce the disturbances due to any mechanical connections with its coarse stage. VCMs are governed by Lorentz law. According to the law and its structure, there are no mechanical connections between coils and magnetic circuits. Moreover, the VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about 5mm2. To break that hurdle, the coarse stage with linear motors is used for the fine stage to move about 200mm2. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. Using MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. For linear motors, Halbach magnet linear motor is proposed and optimally designed in this paper. In addition, for their smooth movements without any frictions, guide systems of the DDS are composed of air bearings. And then, precisely to get their positions, linear scales with 0.1um resolution are used for the coarse's XY motions and plane mirror laser interferometers with 20nm for the fine's XYθz. On scanning, the two stages have same trajectories and are controlled. The control algorithm is Parallel method. The embodied ultra-precision scanning system has about 100nm tracking error and in-positioning stability.

Paper Details

Date Published: 21 March 2006
PDF: 6 pages
Proc. SPIE 6040, ICMIT 2005: Mechatronics, MEMS, and Smart Materials, 60401C (21 March 2006); doi: 10.1117/12.664218
Show Author Affiliations
Ki-Hyun Kim, Korea Advanced Institute of Science and Technology (South Korea)
Young-Man Choi, Korea Advanced Institute of Science and Technology (South Korea)
Dae-Gab Gweon, Korea Advanced Institute of Science and Technology (South Korea)
Dong-Pyo Hong, Chonbuk National Univ. (South Korea)
Koung-Suk Kim, Chosun Univ. (South Korea)
Suk-Won Lee, SAMSUNG Electronics Co., Ltd. (South Korea)
Moon-Gu Lee, SAMSUNG Electronics Co., Ltd. (South Korea)

Published in SPIE Proceedings Vol. 6040:
ICMIT 2005: Mechatronics, MEMS, and Smart Materials
Yunlong Wei; Kil To Chong; Takayuki Takahashi; Shengping Liu; Zushu Li; Zhongwei Jiang; Jin Young Choi, Editor(s)

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