2005 Fiscal Year Final Research Report Summary
Development of Picometer Positioning System and its Application for Ultraprecision Machining
| Project/Area Number |
15360071
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Production engineering/Processing studies
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| Research Institution | Tottori University |
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Principal Investigator |
MIZUMOTO Hiroshi Tottori University, Fac. of Engineering, Professor, 工学部, 教授 (80108795)
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| Co-Investigator(Kenkyū-buntansha) |
ARII Shiro Tottori University, Fac. of Engineering, Ass. Professor, 工学部, 助教授 (80222751)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Positioning / Machine Tool / Nanotechnology / Aerostatic bearing / Ultraprecision Machining / Friction Drive / Active Control |
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| Research Abstract |
For ultraprecision machine tool of the next generation, a tri-mode picometer positioning system is proposed. The positioning system has three positioning modes, namely coarse, fine and ultra-fine mode. The coarse mode for nanometer positioning with long stroke is executed by a twist-roller friction drive (TFD) mechanism and an ordinary AC servomotor. The fine mode for sub-nanometer positioning is also executed by the twist-roller friction drive mechanism, however the mechanism is driven by a piezoelectric actuator. The ultra-fine mode using an active inherent restrictor (AIR) incorporated into the aerostatic guideway realizes the picometer positioning.
Two tri-mode positioning units are arranged in perpendicular, and each mode of the positioning system is controlled by a DSP (motion controller) with a microcomputer. Measured positioning resolution in the coarse mode is 5nm and that in the fine mode is 0.2nm. In the ultra-fine mode, current positioning resolution is 25pm.
For improving the performance of the tri-mode picometer positioning system, we devise an active aerostatic coupling, where the air film thickness on the thrust bearing surface is controlled by the active inherent restrictors (AIRs) and the thrust stiffness of the bearing can be infinite. Therefore, while isolating the lateral vibration from the TFD, the active aerostatic coupling operates as a rigid coupling. The active coupling can also be used as a fine positioning device.
To conclude our research, we expect that the picometer order of positioning resolution will be realized in due course, and the technological knowledge obtained in this research will contribute to the improvement of the positioning technology for ultraprecision machine tools.
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