摘 要 在一般情況下，光碟機本身的伺服控制器可以減少些許聚焦及尋軌誤差，然而在車用光碟機上，常受到外在環境的衝擊或振動等干擾，使得光碟機本身的平衡滾珠產生振動，造成光碟機受到外在環境的振動以及平衡滾珠的振動干擾，此時，光碟機的伺服控制器無法抑制這些外界振動的低頻誤差和平衡滾珠振動的高頻誤差，使得光碟機的讀取的性能下降甚至無法讀取資料。有鑑於此，本論文應 用修正型適應性複合伺服控制器(MAHC)和被動式的吸振海綿於車用光碟機之伺服系統來消除低頻和高頻的誤差，進而改善聚焦及尋軌性能，MAHC 包含前饋式及回饋式主動式干擾消除。本研究採用RVSS-FXLMS 架構，此架構由濾波型最小均方（FXLMS）為基礎，並搭配可變收斂因子（RVSS）演算法，依據控制狀態增加FXLMS 之收斂速度及穩定性。實驗結果顯示， MAHC 和被動式的吸振海綿能有效的消除車用光碟機上經由振動干擾產生之聚焦及尋軌誤差。 ABSTRACT In a vehicular or portable environment, the DVD drives are apt to be influenced by severe external vibration and vibration caused by the balancing balls of spindle to an extent that the focusing and tracking servo errors increase dramatically. This cause the data reading of DVD drives bad or even failed. In this circumstance, the external vibration may usually cause errors of low frequency, and high-frequency errors result from balancing-ball disturbance. To solve this problem, a modified adaptive hybrid servo control (MAHC), an evolution version from the adaptive hybrid control (AHC), was implemented to aid the original servo control system of DVD drive for error cancellation of low frequency, and the balancing-ball disturbance was absorbed by partition dampers. The MAHC structure, based on the FXLMS with robust variable step-size (RVSS-FXLMS) algorithm, was designed and realized with a DSP board. The experimental results demonstrate that the MAHC and dampers can successfully eliminate focusing and tracking errors and improve the reading performance of DVD drive upon the existing architecture of DVD drive in a vehicular environment.
