Multiple robust track-following controller design in hard disk drives

This paper presents a new technique for track-following control in hard disk drives, in order to achieve high tracking precision of magnetic read–write heads uniformly for a huge number of disk drives. The basic idea in this technique is to classify the disk drives into several sets depending on dynamics properties, and to apply a robust controller to each set. The problem of designing the optimal classification of dynamics and the corresponding optimal robust controllers is formulated as a nonconvex optimization problem, for which sub-optimal solutions are to be found numerically. A numerical simulation shows the usefulness of the proposed technique by illustrating a tracking performance improvement. Copyright q 2007 John Wiley & Sons, Ltd.