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Proceedings Paper

Modeling and compensation of flexible modes in 3-DOF H-gantry with decoupling design: a primitive study
Author(s): Si-Lu Chen; Fraj Gharib; Chek Sing Teo; Wei Lin
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Paper Abstract

The special designed 3-DOF direct-drive air bearing decoupling stage has the advantages of high repeatability and free coupling error between different axes. And it is suitable for wafer scanning application. However, due to the flexible joints between the orthogonal axes, the relatively low frequency resonant modes limit the bandwidth of closed loop tracking control. This presentation shows how we obtain the frequency response model of the decouple stage accurately and safely with closed-loop identification approach, using dSPACE modular control systems, and how we use the model to achieve high-speed tracking control using model-based feedforward / feedback composite control. For safety purposes, the electrical portion of decoupled stage is carefully designed with appropriate limit sensors and emergency safety switch. The decoupled stage is controlled by DS1005 modular control system, which gives ultra-high control loop updating rate at 100us. With such high profile controller, we model the frequency response of 3-DOF system using sequential closed-loop relay feedback. From here, the model of rigid body mode and flexible modes are identified. The identified model provides a guideline for trajectory design and closed-loop PID plus feedforward controller design for synchronization of dual-drive X-axis motion. Although the trial on design of decoupling controller has been proposed, internal stability of such decoupling control schemes remains a research issue for our future work.

Paper Details

Date Published: 4 March 2015
PDF: 6 pages
Proc. SPIE 9302, International Conference on Experimental Mechanics 2014, 930239 (4 March 2015); doi: 10.1117/12.2084924
Show Author Affiliations
Si-Lu Chen, Singapore Institute of Manufacturing Technology (Singapore)
Fraj Gharib, Technische Univ. München (Germany)
Ecole Centrale Paris (France)
Chek Sing Teo, Singapore Institute of Manufacturing Technology (Singapore)
Wei Lin, Singapore Institute of Manufacturing Technology (Singapore)

Published in SPIE Proceedings Vol. 9302:
International Conference on Experimental Mechanics 2014
Chenggen Quan; Kemao Qian; Anand Asundi; Fook Siong Chau, Editor(s)

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