基於滑順模態觀測器之無傾角感測滑動模態控制器設計並應用於解決三軸讀寫頭之耦合動態控制

本論文設計配備有滑順模態觀測器之滑順模態控制器運用於新式光學三軸四弦型讀寫頭，以期在無第三軸傾角感測回授的狀態下完成高精確性的三軸定位控制。本篇論文所使用的是四弦型光學讀寫頭具有3個自由度，分別是聚焦(Focusing)、尋軌(Tracking)與傾斜(Tilting)方向。在高密度的光資料存取系統中，維持零傾斜(Tilting)動態的能力是必須且十分重要的。為了實現無傾角感測回授伺服系統設計，吾人利用Lagrange's equation推導出具有3個自由度四弦型光學讀寫頭之動態方程式，再加上考慮讀寫頭上之線圈所產生電磁感應之作用力，導出整體動態方程式。在控制器的設計上主要採用滑動模態控制器(Sliding-mode controller)，目標在於抑制因讀寫頭三軸同動時所產生非線性的耦合動態現象，並達到精確的聚焦、尋軌定位並完成零傾斜的控制。伴隨著控制器的設計，一全階型之高增益觀測器(High-gain observer)被設計於估測讀寫頭之三軸速度，提供滑動模態控制器一低雜訊干擾之速度回授信號，藉以提高控制精確性。此外在本論文中更提出了滑順模態觀測器(Sliding-mode observer)的設計，藉由此觀測器線上估測第三軸傾角之即時動態，此精確估測之第三軸傾角動態可直接提供給所設計之控制器進行三軸同動之定位補償控制，以免除目前商用光學讀寫頭系統需增添第三軸感測器，始能完成三軸同動控制之困擾。在數值模擬部分，將比較不同的控制器與觀測器參數的設定以確認所設定之參數的正確性。最後實際運用dSPACE即時控制之人機介面，透過實作以驗證此控制器在無第三軸傾角感測回授的狀態下，精確定位、零傾斜控制以及降低回授雜訊等效能。

關鍵字

三軸光學讀寫頭；滑動模態控制器；高增益觀測器；滑動模態觀測器

並列摘要

A sliding-mode controller equipped with a sliding-mode observer is synthesized and applied to a novel three-axis four-wire optical pickup for the purpose of sensorless tilt compensation. The three-axis pickup owns the capability to move the lens holder in three directions of focusing, tracking and tilting. It particularly requires for higher data-density optical disks and precision measuring instruments to annihilate non-zero lens tiltings. To achieve the sensorless compensation, we use Lagrange’s equations to derive equations of motion for the lens holder. A sliding-mode controller is then designed to perform dynamic decoupling and forge control efforts toward the goals of precision tracking, focusing and zero tilting. Along with the controller, a full-order high-gain observer is first forged to estimate the moving velocities of the lens holder in order to provide low-noised feedback velocity signals for the designed sliding-mode controller. Moreover, a sliding-mode observer is next designed to perform the on-line tilt estimation of the lens holder. This estimated tilt allows the previously designed sliding-mode controller to be implemented in most existing commercial pickups without additional photodiodes to detect the tilting motion of the lens holder. Simulations are carried out to choose appropriate controller and observer gains. Finally, experiments are conducted to validate the effectiveness of the controller for annihilating lens tilting and the capability of the tilt observer for performing sensorless tilt compensation.

並列關鍵字

Sliding-mode observer ； Three-axis optical pickup ； Sliding-mode controller ； High-gain observer

參考文獻

[1] J. Zhang and L. Cai, “An autofocusing measurement system with a piezoelectric translator,” IEEE/ASME Transactions on Mechatronics, vol. 2, 1997, pp. 213-216.

[2] K. C. Fan, C. Y. Lin and L. H. Shyu, “Development of a low-cost focusing probe measurement,” Measurement Science Technology, vol. 11, 2000, pp. 1-7.

[3] K. C. Fan, C. Y. Lin and L. H. Shyu, “Development of a low-cost autofocusing probe measurement,” Measurement Science Technology, vol. 12, 2001, pp. 2137-2146.

[4] M. Nagasato and I. Hoshino, “Development of two-Axis actuator with small tilt angles for one-piece optical head,” Japanese Journal of Applied Physics, part 1 vol. 35, 1996, pp.392-397.

[6] J. Y. Kang and M. G. Yoon, “Robust control of an active tilting actuator for high-density optical disk,” Proc. the American Control Conference, vol. 2, 1998, pp.861-865.

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基於滑順模態觀測器之無傾角感測滑動模態控制器設計並應用於解決三軸讀寫頭之耦合動態控制

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