Closed-loop adaptive control for electrostatically driven torsional micromirrors

We demonstrate a closed-loop adaptive control scheme for achieving accurate positioning and trajectory tracking of an electrostatically driven torsional micromirror. Compared to the conventional proportional-integral-derivative (PID) controller, the proposed adaptive self-tuning controller has advantages of on-line compensating parameter variations and model uncertainty of the torsional micromirror, resulting from fabrication imperfections. Numerical simulation results utilizing MATLAB indicate that the proposed adaptive controller has a better transient response and can more precisely follow the reference trajectory, compared to the PID control scheme. The torsional micromirror is designed and successfully fabricated using surface micromachining processes. Real-time experimental results demonstrate that the proposed adaptive control is feasible and can improve the performance of the micromirror.

[1]  Thermal actuators used for a micro-optical bench: application for a tunable Fabry-Perot filter , 2003, TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664).

[2]  James M. Florence,et al.  Characterization of a micromechanical spatial light modulator , 1993 .

[3]  Michael C. Roggemann,et al.  Surface micromachined segmented mirrors for adaptive optics , 1999 .

[4]  Lih Y. Lin,et al.  Microactuated micro-XYZ stages for free-space micro-optical bench , 1997, Proceedings IEEE The Tenth Annual International Workshop on Micro Electro Mechanical Systems. An Investigation of Micro Structures, Sensors, Actuators, Machines and Robots.

[5]  M. Wu,et al.  Micromachined vertical three-dimensional micro-fresnel lenses for free-space integrated micro-optics , 1994, 52nd Annual Device Research Conference.

[6]  G. Kino,et al.  Silicon-micromachined scanning confocal optical microscope , 1998 .

[7]  Ke-Min Liao,et al.  Fabrication of micromachined focusing mirrors with seamless reflective surface , 2003, SPIE MOEMS-MEMS.

[8]  A. Gehner,et al.  Deformable Micromirror Devices As Phase Modulating High Resolution Light Valves , 1995, Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95.

[9]  M. Wu.  A low voltage micromachined optical switch by stress-induced bending , 1999, Technical Digest. IEEE International MEMS 99 Conference. Twelfth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.99CH36291).

[10]  C. Mastrangelo,et al.  Robust sliding-mode control of electrostatic torsional micromirrors beyond the pull-in limit , 2003, TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664).

[11]  S. Pannu,et al.  Closed-loop feedback-control system for improved tracking in magnetically actuated micromirrors , 2000, 2000 IEEE/LEOS International Conference on Optical MEMS (Cat. No.00EX399).

[12]  Yee Loy Lam,et al.  A STUDY OF THE STATIC CHARACTERISTICS OF A TORSIONAL MICROMIRROR , 2001 .

[13]  W. E. Nelson,et al.  Digital micromirror device imaging bar for hard copy , 1995, Electronic Imaging.

[14]  H. Fujita,et al.  An out-of-plane polysilicon actuator with a smooth vertical mirror for optical fiber switch application , 1998, 1998 IEEE/LEOS Summer Topical Meeting. Digest. Broadband Optical Networks and Technologies: An Emerging Reality. Optical MEMS. Smart Pixels. Organic Optics and Optoelectronics (Cat. No.98TH8369).

[15]  Y. Lee,et al.  Digitally positioned micromirror for open-loop controlled applications , 2002 .

[16]  J.C. Chiou,et al.  Closed-loop fuzzy control of torsional micromirror with multiple electrostatic electrodes , 2002, IEEE/LEOS International Conference on Optical MEMs.

[17]  Raluca Muller,et al.  Integrated tunable optical interferometer obtained using <111> oriented silicon micromachining , 2003, 2003 International Semiconductor Conference. CAS 2003 Proceedings (IEEE Cat. No.03TH8676).

[18]  Li Fan,et al.  Self-assembled microactuated XYZ stages for optical scanning and alignment , 1997, Proceedings of International Solid State Sensors and Actuators Conference (Transducers '97).

[19]  T. Mitsuyu,et al.  Reflection micro-Fresnel lenses and their use in an integrated focus sensor. , 1989, Applied Optics.

[20]  J. H. Jerman,et al.  Miniature Fabry-Perot interferometers micromachined in silicon for use in optical fiber WDM systems , 1991, TRANSDUCERS '91: 1991 International Conference on Solid-State Sensors and Actuators. Digest of Technical Papers.