運用反模式適應性控制於近場光碟機

Abstract

近場光碟機為目前學術界與工業界所進行中的一種嶄新的光儲存技術，而要達到近場光學所需的精度，精密的伺服控制運用於飛行讀寫頭的控制將是必須的，採用壓電致動器可望補償轉動中光碟片的震動變形。在控制器的設計方面，由於壓電材料表現出明顯地遲滯現象，對於此種非線性現象必須採用不同於線性系統的控制方法，本篇論文裡採用了「反模式適應性控制」的方法來達到控制目的，這個架構是由系統鑑別和反模式控制器所組成, 採用的規則是由最小平方誤差所衍生出的適應性濾波器與類神經概念所構成，結果顯示此控制器對於壓電材料的非線性現象具有良好的補償能力。

Near-field optical disk drives represent a novel technique for optical data recording and its research is undergoing in both academics and industry. To achieve high precision in focusing for near-field data recording, it is essential to develop servo systems that can maintain a constant flying height, for which a piezoelectric bender can compensate the vibration of rotating optical disk. Due to the hysteresis phenomenon in piezoelectric material, advanced controllers other than linear ones must be constructed to accomplish a competent servo system. In this thesis, adaptive inverse control is developed to overcome nonlinear effects. The structure of adaptive inverse control can be separated into two main parts, one is system identification, and the other is controller adaptation. The control scheme is implemented with LMS-sensed adaptive filter or neural networks. Research results demonstrate that the developed method can compensate piezoelectric material hysteresis.