A feedback control system for suppressing rotating disk flutter in hard disk drives

This paper presents a feedback control technique applied to flutter of a rotating disk in an enclosure (hard disk drives). The rotating disk flutter is an aero-elastic instability induced by the coupling of the disk and the air around the disk. The flutter may occur at high rotation speed and the disk will then vibrate with large amplitude. The control system consists of a sensor to pick up the disk vibrations, and the signals are processed to generate a pressure disturbance in the air inside the enclosure. It is demonstrated both analytically and experimentally that, with a proper combination of the control gain and the phase shift, the feedback control can suppress the disk flutter.