Track-Following Control Using Resonant Filter for Dual-Stage-Actuator System in Hard Disk Drives

Abstract

In a magnetic-head positioning control of a hard disk drive (HDD), a lot of disturbances have large gain at high frequencies. This means that the control system must decrease a gain of a sensitivity function at high frequency so that the control system rejects the disturbances. To do so, we have proposed a resonant filter that enables us to decrease the gain of the sensitivity function beyond a servo bandwidth and mechanical resonant frequencies. In this paper, we propose a design method of the resonant filter for a dual-stage-actuator system in the HDD. The proposed method enables us to use the resonant filter in frequencies where the conventional resonant filter makes the control system unstable. Design results with an HDD for nearline storage show that the proposed method is able to reject the disturbances in high frequencies with good robust performance.