A Novel Design of Short-seeking Control for Dual-actuator Hard Disk Drives

This paper discusses short seeking control for a dual-actuator hard disk drive consisting of a coarse actuator (voice coil motor, VCM) and a fine actuator (piezoelectric actuator, PZT). A novel design method is proposed based on the dual-stage track following control and initial value adjustment (IVA). This method, which adjusts the initial values of the track-following controllers for short seeking, makes the use of the feed-forward controller and reference trajectory unnecessary. The proposed design also takes into consideration the saturation property of the fine actuator by using a two-stage IVA scheme: (1) only VCM loop is utilized in the first stage (beyond PZT stroke limit), and IVA is designed to yield a high-speed seeking; (2) PZT loop is switched on when the read/write head approaches the target track in the second stage (within the PZT stroke limit), and IVA is used to produce a fast and smooth response. Simulation results verify the effectiveness of the proposed method. Copyright © 2005 IFAC