Perfect Tracking Control System with Prediction State Observer for Next-Generation Optical Disks

Abstract

Recently, the capacity of optical disk recording systems has been increasing. Optical disk drive systems must realize high-precision tracking control. For this purpose, we previously proposed a tracking control system that is composed of both a robust feedback controller and a zero-phase-error feedforward tracking controller. The proposed feedforward tracking control system effectively suppresses the tracking error caused by track eccentricity. However, it is sometimes difficult for conventional feedforward tracking control systems to realize higher precision in their tracking control. Hence, in this paper we propose a new perfect tracking control (PTC) system with a prediction state observer for next-generation optical disks. The experimental results confirm that the proposed system suppresses the tracking error at a disk rotation speed of 8000 rpm. Therefore, the proposed system realizes high-precision tracking control.

Double Feedforward Control System Based on Precise Disturbance Modeling for Optical Disk

“…We have already proposed an error prediction tracking control system with an equivalentperfect tracking control (E-PTC) system. [9][10][11] The experimental results of the E-PTC system indicated adequate suppression of the tracking error. However, it is difficult to design the control parameter for actual multi-harmonic disturbances.…”

“…The amplitude and phase of the inverseoperated eccentric disturbance are respectively obtained using Eqs. (10) and (11). SðzÞ is the discretized sensitivity function of the feedback control system.…”

“…Using the pseudoinverse matrix, we have already proposed that it is possible to compose the E-PTC system. [9][10][11] The E-PTC system enables the entire system to be composed of a single sampling frequency. The inverse system of the E-PTC system can be represented in its pre-multi-rate state, as shown in Eqs.…”

Fine Tracking Control System based on Double Equivalent-Perfect Tracking Control System and Error-Based Disturbance Observer for Optical Disk

“…We previously proposed a hybrid tracking control system that combined a perfect tracking control (PTC) (8)- (11) and a prediction state observer for high-precision tracking control. The conventional PTC system realizes a high-precision system; however, the whole system is complicated, and the processing time is long.…”

Focusing control system for suppressing multi-harmonic disturbances in high speed optical disk systems

“…Moreover, designing a feedforward controller is difficult because general optical disk systems cannot obtain a reference signal [3], [4], [5]. In order to adjust for these problems, we have already proposed several tracking control systems such as the robust feedforward tracking controller based on zero phase error tracking (ZPET) control and prediction of tracking error [6], [7], a ZPET controller with a multi-harmonic disturbance suppression loop [8], and a high precision feedforward controller based on a perfect tracking control (PTC) system [9]. However, theoretical proposals of focusing control systems are not sufficient.…”