| Project/Area Number |
63850030
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
機械工作
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
SHIMOKOHBE Akira Department of Mechanical Engineering for Production, Faculty of Engineering, Tokyo Institute of Technology, Professor, 工学部・生産機械工学科, 教授 (40016796)
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| Co-Investigator(Kenkyū-buntansha) |
MORIYAMA Shigeo Hitachi Ltd., Central Research Laboratory, Senior Development Engineer, 中央研究所, 主任研究員
TOYAMA Akira Dai-ichi Sokuhan, Advisor, 顧問
AOYAMA Hisayuki Department of Precision Engineering, Faculty of Engineering, Shizuoka University, 工学部・精密工学科, 助教授 (40159306)
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| Project Period (FY) |
1988 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥17,200,000 (Direct Cost: ¥17,200,000)
Fiscal Year 1989: ¥4,500,000 (Direct Cost: ¥4,500,000)
Fiscal Year 1988: ¥12,700,000 (Direct Cost: ¥12,700,000)
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| Keywords | Air Bearing / Controlled Bearing / Active Damping / Ultra Precise Positioning / Piezoelectric Actuator / Ultra Precise Mechanism / Mechatronics |
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| Research Abstract |
An air journal bearing, capable of controlling two radial motion of its axis was proposed, constructed and its good performance at low axis rotation speed was demonstrated. This step of research focuses on problems which occur, when the axis is rotated at a high speed of more than 1000rpm as well as solutions for these problems.
An air turbine was installed in the bearing. By this turbine, the axis is rotated without mechanical contact with a constant and high speed of more than 1000rpm. In order to execute a repetitive control (mentioned later), two noncontact magnetoresistive elements was installed. These elements generate 400 pulses per each revolution of the axis. These pulses express the angle of rotation of the axis.
In preliminary experiments, a rotation accuracy of 0.3mum was obtained when the axis is rotating at 1000rpin. By using a basic controller of PID-PDD^2 type, the rotation accuracy was improved to less than 0.lmum. A better accuracy could not be achieved. The remaining rotation error had repeatability and it was caused by roundness errors in the axis and the bearing. In order to reduce the error, a repetitive controller (a 32 bit microprocessor) was added to the basic controller. Experiments showed that, even with a imbalance in the axis, a motion accuracy better than 25nm can be achieved. Moreover, a fast and ultra-precise positioning of the rotating axis is possible.
Because of vibrations in the bearing structure, the control was not possible at a rotation speed higher than 1000rpm. This problem was solved by changing the axis and reducing the air film thickness of 20mum to 10mum. Experiments showed that at 1740rpm, the rotation accuracy of the uncontrolled bearing is approximately 0.6mum. This accuracy is improved to less than 0.2mum by the basic controller and to less than 15nm by the repetitive controller.
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