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Development of Normally Closed Type of Magnetorheological Clutch and its Application to Safe Torque Control System of Human-Collaborative Robot

Japan National Institute of Occupational Safety and Health (JNIOSH) 1-4-6 Umezono, Kiyose, Tokyo 204-0024, Japan, saitot{at}s.jniosh.go.jp

Hiroyasu Ikeda

Japan National Institute of Occupational Safety and Health (JNIOSH) 1-4-6 Umezono, Kiyose, Tokyo 204-0024, Japan

In this study, a normally closed (NC) type clutch using magnetorheological (MR) suspension and a rare-earth permanent magnet is proposed as a safety device for human-collaborative robots. This clutch can transmit an effective torque under various conditions and function as a holding brake and a changeable torque limiter. To design this clutch to achieve both good controllable characteristics and safety performance, the normally closed structure with a permanent magnet was realized by placing two facing magnetic poles asymmetrically for efficient generation of the magnetic field, and by adopting the multi-sheet rotor for the improvement of the torque output. As the analysis results show, it was confirmed that the three-sheet rotor obtained about 1.5 times torque output as much as the single-sheet rotor. When the exciting current was 0.8A, the transmitted torque marked the minimum; when the exiting current was 0A, the torque output of approx. 41 Nm was generated with the time constant of 0.15 s.

Key Words: magnetorheological suspension • robot • safety • collaborative operation • clutch • normally closed type • rare-earth permanent magnet.

References

• International Organization for Standardization. 2006. ``ISO 10218-1, Robots for industrial environments - Safety requirements — Part 1: Robot,'' 17.
• Lampe, D., Thess, A. and Dotzauer, C. 1998. ``MRF-Clutch-Design Consideration and Performance,'' Proceedings of 6th International Conference on New Actuators, 449—450.
• Lee, U., Kim, D., Hur, N. and Jeon, D. 1999. ``Design Analysis and Experimental Evaluation of an MR Fluid Clutch,'' Journal of Intelligent Material Systems and Structures, 10(9):701—707.[Abstract/Free Full Text]
• Neelakantan, V.A. and Washington, G.N. 2005. ``Modeling and Reduction of Centrifuging in Magnetorheological (MR) Transmission Clutches for Automotive Applications,'' Journal of Intelligent Material Systems and Structures, 16(9):703—711.[Abstract]
• Saito, T. and Ikeda, H. 2005. ``Safe Torque Control System of Human-collaborative Material Handling Robot for Crush Prevention,'' Symposium Digest of ISR2005, 57.

Journal of Intelligent Material Systems and Structures, Vol. 18, No. 12, 1181-1185 (2007)
DOI: 10.1177/1045389X07084755


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This Article Abstract Free Full Text (Free PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Saito, T. Articles by Ikeda, H. Search for Related Content Social Bookmarking                         What's this?