Zero phase error tracking control system with multi harmonics disturbance suppression loop

Recently, on the view point of capacity of memory, the media of optical disk recording system is increasing. Moreover, its disk rotation speed will be increasing according to its large memory capacity, such as more than 10000[rpm]. The optical disk system has a radial run-out originate from the disk eccentricity. For this reason, the optical disk system has the periodic disturbance which is synchronized to its disk rotation speed. In order to suppress this periodic disturbance, we have proposed the robust feedforword tracking controller based on Zero Phase Error Tracking (ZPET) control. The optical disk system has the periodic harmonics disturbance. However, it is difficult for the conventional robust feedforword tracking controller to suppress the periodic high order harmonics disturbance. In order to overcome this problem, this paper proposes a new ZPET control system with multi harmonics disturbance suppression loop. The experimental results point out that the proposed tracking control system has a precise tracking response against both periodic primary harmonics disturbance and periodic high order harmonics disturbance.