Compensating for ZOH-Induced Residual Vibrations in Head-Positioning Control of Hard Disk Drives

In a hard disk drive, residual vibrations induced by a zero-order-hold may lead to destruction of user data. Therefore, we developed a control method that can reduce such residual vibrations in the head-positioning control system of a hard disk drive. This study is based on a shock response spectrum (SRS) analysis that handles the transient-state characteristics of mechanical resonances. The control method uses multirate notch filters that modify the acceleration input signals beyond the Nyquist frequency. The results of the SRS analyses showed that the multirate notch filter was able to decrease the amplitude of residual vibrations caused by the mechanical resonances around the sampling frequency. Simulation and experimental results for a track-seeking control in a hard disk drive demonstrated the validity of the proposed method.