Sub-Nanometer Resolution Positioning Device Driven by New Type of Linear Motor with Linear Ball Guideways – Considering Time Lag of Electric Control System –
Toshiharu Tanaka*, Jiro Otsuka**, Ikuro Masuda**,
Yasuaki Aoyama***, and Asuka Inagaki*
*Toyota National College of Technology, 2-1 Eisei, Toyota, Aichi 471-8525, Japan
**Shizuoka Institute of Science and Technology, 2200-2 Toyosawa, Fukuroi, Shizuoka 437-8555, Japan
***Hitachi Ltd. Hitachi Research Laboratory, 7-1-1 Omika-cho, Hitachi-shi, Ibaraki-ken, Japan
We have developed an ultra-precision positioning device that has the following characteristics: 1) The 210 mm strokes stage is driven by a new type of linear motor called “Tunnel Actuator (TA).” 2) The stage has very rigid structure so as not to cause vibration and to achieve high resolution for its feed-back system. 3) The stage is supported by linear ball guideways that have nonlinear spring behavior in the small stroke range. 4) Much attention has been paid to the time lag of the electric control system in the PID control using a linear encoder of 0.034 nm resolution for the feed-back system. The electric control system compensates for the disturbance of induced electromotive voltage that is generated in proportion to the stage velocity. We have studied how the equivalent time constant T of the control system affects the stage displacement deviation Δx when the command of stage displacement xr is kept at zero. The following results have been obtained: 1)With a decrease in time constant T of the current control system, the change in the motor current Io becomes smaller, and, at the same time, the change in stage deviation Δx becomes smaller. 2) At the smallest time constant T of the current system, a displacement resolution of 0.2 nm has been obtained under the nonlinear spring behavior of linear ball guideways. 3) There is a possibility of obtaining a displacement resolution of less than 0.1 nm with a further decrease in T.
-  T. Oiwa and M. Katsuki, “Survey of Questionnaire on Ultra-Precision Positioning,” J. of The Japan Society for Precision Engineering, Vol.74, No.10, p. 1027, 2008. (in Japanese)
-  S. Futami and A. Furutani, “Nanometer Positioning Using AC Linear Motor and Rolling Guide (1st Report),” J. of The Japan Society for Precision Engineering, Vol.57, No.3, p. 556, 1991. (in Japanese)
-  S. Makinouchi, “History of Semiconductor Lithography Technologies,” Proc. of Regular Meeting of Technical Committee of Ultra-Precision Positioning, 2007-1, p. 22, 2007. (in Japanese)
-  J. Otsuka, S. Ichikawa, T. Masuda, and K. Suzuki, “Development of a Small Ultraprecision Positioning Device with 5nm Resolution,” Measurement Science and Technology, Vol.16, p. 2186, 2005.
-  J. Otsuka, S. Ichikawa, and T. Masuda, “Small-sized Ultra-Precision Positioning Device with 1nm Resolution by New Drive System Using Ball Screw,” Proc. of 2006 JSPE Autumn Meeting, L09, p. 857, 2006. (in Japanese)
-  Edit Committee of The Practical Precise Positioning Technology Handbook, “Practical Handbook of Precision Positioning Technology,” Industrial Technology Service Center Co., p. 491, 2008. (in Japanese)
-  J. Otsuka, T. Tanaka, and I. Masuda, “Development of Sub-Nanometer Positioning Device Combining a New Linear Motor with Linear Motion Ball Guide Ways,” Measurement Science and Technology, Vol.21 p. 037001, 2010.
-  H. J. Kim, J. Nakatsugawa, K. Sakai, and H. Shibata, “High-Acceleration Linear Motor, “Tunnel Actuator”,” J. of The Magnetics Society of Japan, Vol.29, No.3, p. 199, 2005. (in Japanese)
-  T. Tanaka, J. Otsuka, I. Masuda, Y. Itou, and Y. Aoyama, “Ultraprecision Positioning by New Type of Linear Motor Drive – Challenge to Sub-Nanometer Positioning Resolution by Paying Attention to Electric Current Control System –,” J. of The Japan Society for Precision Engineering, Vol.76, No.12, p. 1364, 2010. (in Japanese)
-  J. Otsuka, “Technology of Ultra-precision Positioning,” Yokendo Co., Ltd., p. 27, 130, 2010. (in Japanese)
-  J. Otsuka and T. Masuda,“The Influence of Nonlinear Spring Behavior of Rolling Elements on Ultraprecision Positioning Control Systems,” Nanotechnology, Vol.9, p. 85, 1998.
-  J. Otsuka, I. Aoki, and T. Ishikawa, “A Study on Nonlinear Spring Behavior of Rolling Elements (1st Report) – Tow Simple Measuring Methods –,” J. of The Japan Society for Precision Engineering, Vol.66, No.6, p. 944, 2000. (in Japanese)
-  T. Takahashi, “Linear Motion Ball Guide Drawing Near the Nanometer Level Accuracy,” J. of The Japan Society for Precision Engineering, Vol.74, No.9, p. 909, 2008. (in Japanese)
-  SonyManufacturing Systems Corp., “Linear Scale BS SERIES Catalog,” 028J-0511-05-01A, 2005.
-  N. Suda, “PID Control,” Asakura Publishing Co., Ltd., p. 39, 1994. (in Japanese)
-  Miyazaki Engineering & Research Co., “Foundation and Fact of Automatic Control Mastered by Computer Simulation.” (in Japanese)
http://www.miyazaki-gijutsu.com/series/control 513.html, 2010
-  Yasukawa Electric Mfg Co., Ltd., “Servo Technological Introduction,” The Nikkan Kogyo Shinbun, Ltd., p. 70, 1992. (in Japanese)
-  S. Futami, “Controller Outline for High and Ultra Precision Positioning,” Proc. of Regular Meeting of Technical Committee of Ultra-precision Positioning, 2006-1, p. 1, 2006. (in Japanese)
-  I. Masuda, “Ultra-Precision Positioning and Control Method by Linear Actuator,” e-journal High-Precise Positioning Technology and Application, p. 59, 2008. (in Japanese)
-  PMAC JAPAN Co., Ltd., “UMAC-Turvo Catalog,” 2007. (in Japanese)
-  Servoland Corp., “MOVO SVN Manual,” 7, 2006. (in Japanese)
-  N. Okubo, “Mechanical Modal Analysis,” Chuo University Press, p. 52, 1989. (in Japanese)