Vibration Suppression PTC of Hard Disk Drives with Multirate Feedback Control

In the head positioning systems of hard disk drives (HDDs), multirate control is very effective since the sampling frequency is restricted by the mechanism. In the short- span seeking-mode, the mechanical vibration is getting crucial obstruction to achieve high-speed data access. In this paper, a high-order vibration suppression perfect tracking control (PTC) method is proposed based on multirate feedforward control. Moreover, the robustness against variation of primary vibration frequency is improved by a multirate feedback controller.