Active high frequency vibration rejection in hard disk drives

This paper presents an active vibration rejection control technique to reject actuator arm resonance modes using a PZT sensor attached to the actuator arm. A Multi-rate digital implementation is proposed for high frequency active vibration rejection over the sector induced sampling frequency. The vibration control signal can be synchronized with the slow state feedback control input such that the two control signals are summed and applied to the voice coil motor. After obtaining a transfer function from head position to PZT sensor output, a method is proposed on how to design the vibration rejection controller. An application example demonstrates the utility of the proposed active vibration rejection scheme.