PIVOT FRICTION COMPENSATION USING AN ACCELEROMETER AND A DISTURBANCE OBSERVER FOR HARD-DISK DRIVES

This paper is concerned with the combined use of an accelerometer and a Disturbance Observer (DOB) to compensate for pivot nonlinearities th at are subject to uncertainties in Hard Disk Drives (HDDs). The DOE es timates the bias due to pivot nonlinearities such as friction, and thi s estimate becomes a feedback signal for bias cancellation. Experiment s have confirmed that the cancellation scheme is effective in the freq uency range from 0 to 700 Hz. Since the proposed cancellation scheme c an be implemented as an analog system, it provides wider-bandwidth bia s rejection and better settling performance than traditional bias comp ensation schemes such as integral action based on sampled position err or signal. The proposed method can make the distribution of the positi oning error at the end of high-speed track-to-track seeks much smaller than that when a digital integral action is used.