Optimal Focus Servo Control for Optical Data Storage Systems

In the next generation optical data storage systems, the lens-disk interface gap and the tolerance of the focus error will reduce dramatically. The rotation of the spindle motor could produce repetitive disturbances to the focus servo system due to the misalignment and the skew of the disk, therefore affect the focus precision and cause the lens-disk collision. In this paper, an optimal Q-parameterized controller design approach is proposed and the optimization constraints are formulated in matrix inequalities. The approach is finally evaluated in an optical data storage experimental system.