ROBUST H-INFINITY CONTROL WITH MULTIPLE CONSTRAINTS FOR THE TRACK-FOLLOWING SYSTEM OF AN OPTICAL DISK-DRIVE

In this paper, we design a tracking controller which satisfies transie nt response specifications and maintains tracking error within a toler able limit for the uncertain track-following system of an optical disk drive, To this end, a robust H-infinity control problem with regional stability constraints and sinusoidal disturbance rejection is conside red. The internal model principle is used for rejecting the sinusoidal disturbance caused by eccentric rotation of the disk. We show that a condition satisfying the regional stability constraints can be express ed in terms of a linear matrix inequality (LMI) using the Lyapunov the ory and S-procedure, Finally, a tracking controller is obtained by sol ving an LMI optimization problem involving two LMI's, The proposed con troller design method is evaluated through an experiment.