Two-dimensional Control of Self-servo Track Writing for Hard Disk Drives

Abstract

Self-servo track writing (SSTW) process for hard disk drives (HDDs) is described by using a two-dimensional (2-D) model, with which the error propagation containment problem of the SSTW is formulated as 2-D stabilization problem, and the position error minimization problem is formulated as 2-D H2 control problem. The adopted 2-D controller is designed with easily implemented linear matrix inequality (LMI) approach. With the stored error information of previous track, the 2-D control scheme is realizable. The simulation results demonstrate that the error propagation is prevented by the 2-D control scheme and the positioning accuracy is remarkably improved by the 2-D H2 control scheme. Also, from the 2-D controller servo performance is evaluated in usually concerned 1-D sense.

Decoupled direct tracking control system based on use of a virtual track for multilayer disk with a separate guide layer

“…Since data are recorded on the basis of the recording spot, such a shift can cause previously recorded data marks to be overwritten. One solution to this problem is the adjacent track servo system with linear positioning method developed by Urakawa et al [19][20][21][22][23] However, the need to form a particular pit structure on the servo layer to maintain a continuous linear position on the groove-less disk could increase the disk fabrication cost. An alternative is the advanced radial position control system developed by Tanaka et al, [24][25][26][27][28] but its use of feed-forward control it is not sufficiently robust against shock and vibration.…”