Earliest switch-on of dual-stage actuation in hard disk drives

In conventional track-settling process, dual-stage actuation (DSA) is not activated until the read/write head is in close proximity to the target track so that chances of saturation are reduced. In this paper, we propose an earliest switch-on scheme based on the calculation of the exact saturation boundary, considering both position error signal and voice coil motor velocity error. It allows the DSA loop to be switched on earlier than current practices while piezoelectric actuators remain unsaturated. Simulations on a 2.5′′\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$''$$\end{document} commercially available hard disk drive show that the proposed scheme can reduce the post-seek oscillation and shorten the 5 % track-settling time by more than 16 % in the presence of in-drive disturbances.