Robust tracking servo system considering force disturbance for optical disk recording system

This paper proposes a new robust tracking servo system for optical disk recording system with feedforward controller based on prediction of tracking error. In optical recording systems, the feedback servo system must suppress the influence of the force disturbance and parameter variation. For this purpose, this paper designs the robust feedback control system by using the coprime factorization and disturbance observer. The detecting signal of optical disk recording system is only a tracking error. Hence, the feedforward controller of the proposed tracking control system is constructed based on both "zero phase error tracking" (ZPET) control theory and prediction of tracking error. The experimental results point out that the proposed system has a quick and precise tracking response and keeps the residual tracking error below tolerance.