Compensation of mechanical resonances by adaptive feed-forward cancellation for head positioning control system in hard disk drives

Abstract

To increase recording density, a head positioning control system of a hard disk drive (HDD) has to compensate for vibration due to mechanical resonances of the system. In this study, a novel scheme of an adaptive feedforward cancellation (AFC) is proposed to compensate for the vibration due to the mechanical resonances. Compared to a notch filter, which is commonly used to compensate for the vibration, the proposed AFC has the advantage of estimating the amplitude of the vibration from the output signal. In addition, although the proposed AFC can be implemented as a discrete system, the design parameters: frequency, damping ratio, and gain can be set directly in a digital signal processor. The proposed control system was applied to a dual-stage actuator system, which is the mainstream head positioning control system of the current HDDs. The results indicate that the proposed system could compensate for the vibration due to the mechanical resonance.