Methods for Closed-loop Compensation of Ultra-high Frequency Disturbances in Hard Disk Drives and Hard Disk Drives Utilizing Same

Abstract

The importance of safe and flexible disturbance rejection at high frequencies has been ever increasing in modem control systems. For example, new applications of hard disk drives (HDD) require that the HDD control system be robust to (e.g., have the ability to reject, attenuate) vibration disturbances that can occur at, for example, 5000 HZ and 6000 HZ, which capability has, thus far, been unattainable. Theoretical limi tations prevent conventional disturbance observer schemes from being applied to environments is susceptible to ultra-high (e.g., 4000 HZ and above) frequency disturbance environments. This invention addresses the challenge and provide methods for accurately controlling hard disk drives to function in presence of ultra-high frequency disturbances.