Pivot Friction Compensation Using an Accelerometer and a Disturbance Observer for Hard Disk Drives

Abstract

This report is concerned with the compensation of pivot bias in hard disk drives by a combined use of an accelerometer and a disturbance observer (DOB). Since the proposed method can be implemented as an analog system, it provides wider bandwidth control compared with traditional digital bias compensation scheme such as an integral action. The difference is demonstrated by a sequence of O.5msec head positioning. The probability that the tracking error at the end of each positioning is within ±5% of the track pitch has been improved from 0.35 (an integral action) to 0.80.