Robust double feedforward tracking control system using error based disturbance observer for optical disk systems

Recently, the size of digital content has continued to increase. In order to cope, manufacturers of digital storage media have tried to increase capacity by narrowing the track pitch of these digital storage media. In addition, recent advancements in technology have resulted in a new optical disk has a rotation speed of over 15,000 rpm. Considering all these factors, we believe that a high-precision tracking control system is needed for optical disks. Consequently, this paper proposes a new robust double feedforward control (RDFFC) system for high-precision control. The proposed system is constructed by using two error prediction-based zero phase error tracking (ZPET) control systems, and includes an error-based disturbance observer (EDOB) that uses notch filter to suppress non-periodic disturbances. The proposed control system is designed for DDU-1000 for DVD. The experimental results confirm that our proposed system is practicable and effective.