Compensation of Shock-induced Head Skew for Hard Disk Drives

Head skew among multiple heads in hard disk drives (HDDs) is normally calibrated in factory, and is applied by servo controller to estimate position of destination head for head switching seeking. In response to operating or nonoperation shock, additional head skew error across stroke may be introduced, which could degrade drive performance in terms of long access time and acoustic issue. In this paper, a quick check method of head skew error during servo startup is proposed, where a sector-dependent filtering scheme for reliable head skew calibration is developed. Test result demonstrating the effective compensation of shock-induced head skew is summarized.