Abstract
光碟挾著大量存取和半永久保存資料的優點而深具發展潛力和應用價值，然而光碟機的資料讀取頭到達定位所需的時間 ( 約四十毫秒 )卻近於硬碟機的兩倍。因此縮短光碟機的定位時間是未來發展上的關鍵技術 。本論文的研究即為了縮短光碟機的定位時間而發展出來的。造成光碟機的資料讀取頭不能夠完成迅速而又精確定位的原因乃為光碟機的輸出感測器受到雜訊的嚴重干擾所致。其中又以軌數誤數 ( Track Miscount ) 和感測延遲 ( Detection Delay ) 這兩種雜訊的影響最為顯著。本論文中提出了一個位置與速度估算器去校正軌數誤數和感測延遲所造成的輸出誤差。這個估算器包括一個傳統的卡門濾波器 ( Kalman Filter ) 和一個運算器去校正軌數誤數和感測延遲。相較於其他方法，這個估算器的架構和運算都比較簡單。然後我們把所提出來的估算器和一強韌性、近時間最佳化控制系統 ( Robust, Near Time- Optimal Control System ) 結合起來，以使得整個系統能夠完成快速又精確的定位動作。電腦程式模擬的結果顯示吾人所提出來的估算器能夠在軌數誤數和感測延遲的影響之下估算出準確的位置和速度，使得整個系統的定位性能大為改善。Optical disk is promising in development and applicationadvantages in semi-permanent property and large storage memory.the average accessing time in optical disk drives is over 40 mstwice of the average accessing time in hard disk drives. It isfor some applications. The motivation of this thesis is toaccessing time in an optical disk drive. The main problems thatprevent an optical head from achieving and rapid positioningare track miscounts and a detection delay due to the sensornoise of the optical track counter (the measurement device ofan optical disk drive). In this thesis, a velocity and positionestimator is proposed position and velocity errors caused bytrack miscounts and/or a detection delay. The estimatorconsists of a conventional Kalman filter and a function blockto correct track and a detection delay. The structure and thealgorithm of this block are relatively simple. And the presentestimation algorithm is incorporated into a robust, nearntrolsystem so as to let the whole system can achieve more accuratepositioning. The simulation results indicate that the presentestimation algorithm can achieve accurate position and velocityestimations under the influence of track miscounts and adetection delay. And the system performance is significantlyimproved.