- 學位論文
DVD-ROM聚焦及循軌控制器設計
Design of Focusing and Tracking Controllers for DVD-ROM
摘要
DVD-ROM內包含了很多複雜的伺服系統，其中以聚焦及循軌伺服系統較為重要，聚焦及循軌伺服控制器均使用領先落後補償器作為控制器。目前產業界設計DVD-ROM伺服控制器仍採用雙線性轉換(bilinear transformation) ，經轉換後在w平面上設計控制器，但由於受到專用控制晶片的控制器結構與限制的影響，在設計後可能無法直接套用至晶片上使用，而需反覆設計。本文利用系統鑑別(system identification)的方式，求出DVD-ROM受控系統轉移函數，利用已知的轉移函數去設計基因法則，最後再以基因演算法強大的搜尋能力，達到控制器參數自動調整的目的，使控制器達到最佳的設計效果，同時大幅減少工程師在設計DVD光碟機伺服控制器上的麻煩以及提昇設計效率。 對於聚焦及循軌伺服系統受控系統之不確定性，量化回授理論(Quantitative Feedback Theory, QFT)能有效解決受控廠之不確定性，卻依然能滿足多個性能規格的有效設計方法。本文利用基因法則自動作QFT之迴路設計，應用於DVD-ROM光碟機聚焦及循軌伺服系統，以確保設計之精確度及減少人為之不斷誤試，達到控制器自動設計之功能，並量測驗證其結果。
並列摘要
In the DVD-ROM, there are many complicated servo systems. The focusing and tracking servo systems are more important than other servo systems in DVD-ROM. The lead-lag compensator is employed as the focusing and tracking controller. Toady’s DVD-ROM manufactures still use the bilinear transformation to design servo controller in w-plane. In the special purpose servo chip for the DVD-ROM, because of the effect of the structure of the controller and the limits of the chip, the result of the controllers may not be implemented in the chip after designing, and redesigning is regained again and again. In this paper, the transfer function of DVD-ROM controlled system is evaluated by the method of system identification. To design for genetic algorithm, the known transfer function is used to make the genetic algorithm demonstrates its powerful searching capability can achieve the aim to automatic adjustment of controller parameters and let the controller work in the best performance level. Meanwhile, the above proposed method can significantly decrease lots of inconvenience and increase more design efficiency when engineers design the controller of DVD-ROM. Concerning about the uncertainty of both focusing and tracing controlled system, Quantitative Feedback Theory (QFT) is considered as an effective method for uncertain plants to satisfy the assigned specifications. In this paper, a methodology using the genetic algorithm is proposed to improve the design accuracy, The methodology has also been applied to the design of focus and tracking servo controllers for the DVD-ROM, to reduce the work of tedious trial and error process and to enable automatic design procedure.