光碟機軌跡偏擺之適應性壓制法則

Abstract

由於現在的光儲存系統追求高容量、高精密度與快速的存取，如光碟機對碟片的存取，使得碟片間的軌距需要越來越小，要求的循軌精度越來越嚴格。從以前的CD到DVD，在碟片旋轉的過程中，由於碟片晃動產生鎖軌的誤差，如何在高精度的要求下穩定的鎖軌成為重要議題。本論文針對此點在光碟機碟片偏擺所造成的循軌誤差外加一個適應性前饋控制器(AFC controller)，使碟片偏轉(runout)的穩態誤差(steady error)可以做更有效的壓抑。利用在原系統加入AFC控制器可以對特定諧波作額外的補償，在不影響原系統的穩定性下達到降低穩態誤差的要求。本論文使用Matlab這套軟體作系統的控制模擬，並把理論實現在DVD的循軌上，利用DSP做為實現AFC控制器的硬體，而外加AFC取樣頻率的設計則是利用FPGA來實現；由實驗的結果可以發現，其對穩態誤差確實有補償的效果。

The constant dist runout experienced by the removable recording media becomes more serious as the track density grows higher. To achieve good recording quality, it becomes more and more important for the servo system to treat the disk runout. In this thesis, the adaptive feed-forward cancellation (AFC) of the disk runout is discussed. The General Purpose Optical Disk Evaluation Kit (GPODEK) is used for the implementation. The AFC is installed in the Digital Signal Processor (DSP) module in the GPODEK. The AFC injects an additional signal to the servo controller to suppress the disk runout. The thesis performed both MATLAB simulations and experiments. The results show that the proposed algorithm is effective and is easy to implement.