DVD光驱之DSP主动式聚焦控制器

摘要：

DVD 具有储存密度高、体积小与保存方便等优点，越来越被广泛

地应用，而由于其较高的储存数据密度，因此雷射的读写控制势必更加

精密、实时与稳定，而在携带式的DVD 光驱产品因外在环境影响更

必须特别注意其读取与写入的稳定性。本论文即提出一有效的控制方式

以解决携带式光驱受外在扰动聚焦不稳定的问题，主要是以主动式

(active)前馈控制(feedforward control)的方式有效消除外来扰动对光学头

的影响，控制器使用适应性滤波器(adaptive filter)来实现，其较被动式控

制与回馈控制(feedback control)更能有效消除低频及宽带的扰动，其即为

携带式光驱最须克服的难题。

而整体实验为了提高与市面产品的兼容性，也开发了一数字信号处

理器(digital signal processor，DSP)嵌入式(embedded)系统以实现适应性

控制的运算并可提供其它控制系统之开发核心。实验结果显示在窄频

(single tone)扰动可迅速的(约0.3秒内)消除了约32dB，而宽带(broad band)

方面则消除16.7dB，证明了所提出的主动式前馈控制对低频且宽带的扰

动有效的消除，进而达到光学头聚焦的稳定。

II：

DVD Optical Disk Driver with a DSP-Embedded

Active Focusing Controller

Abstract

DVD optical disk driver is becoming more and more popular because

of the advantages of high storage density, compact volume, and easy

preservation. Therefore, the controller of the driver must focus the laser spot

precisely and stably. In this thesis, an active feedforward controller is set up

to eliminate external disturbance with s stable focusing control. An adaptive

digital filter is designed based on fixed-X least mean square(FXLMS)

algorithm to implement the controller that can more efficiently

suppress the low frequency and broad band noises.

In order to match the real DVD camera recorder, we develop a 32-bit

floating point DSP embedded system to implement the adaptive digital filter.

Moreover, the DSP embedded system can be used as a control core in

developing other system. The experimental results demonstrate that the

active controller can suppress a single-tone disturbance with 32dB and a

broad-band disturbance with 16.7dB. It is proven that the active feedforward

controller can stably control the focusing actuator with the suppressing

effect of external disturbance.