Add-On Feedforward Compensation for Vibration Rejection in HDD

The applications of the hard disk drive (HDD) in mobile and compact devices pose higher requirement on the vibration-rejection capability of HDD servo control. A novel vibration-compensation method is proposed in this paper. It is an add-on feedforward scheme, and the add-on feature will be turned on only in the specific vibration environment. The scheme comprises two parts: the vibration detection through the analysis of the vibration sensor output, and the vibration compensation through the add-on feature. One major advantage of this method over conventional methods applied in HDD is that the vibration rejection in some frequencies can be improved without the compromise of the performance in other frequencies. The scheme is not based on an accurate modeling, therefore, it is less sensitive to the variation of the plant parameters. The transient response in switching on or off the add-on feature is shortened by the reset control. The scheme is implemented in real HDD, and the experimental results prove the effectiveness of the scheme.