Design of Q-parameterized controller for focus servo system under the circumstance of anti-collision

In the next generation optical data storage systems, the lens-disk interface gap and the tolerance of the focus error will reduce dramatically, however, the rotation of the spindle motor could produce sinusoidal disturbances to the focus actuator system due to the skew of the disk and system mechanical vibrations, which consequently affect the focus precision and even cause the lens-disk collision. In order to avoid the lens-disk collision and increase the focus control precision, an optimal Q -parameterized controller is proposed in this paper. The parameter of the controller is solved based on some properly formulated linear matrix inequalities (LMIs). Simulation results show that the designed controller has an effective anti-collision capability with a good focus precision.