A Youla-parameterized Gap Control for Next Generation of Optical Storage Systems

With the development of ultra-high-density optical storage technology, the density of storage media is getting higher and higher, but the increase of the capacity of the optical disk leads to the reduce of the lens-disk interface gap and the tolerance of the focus error dramatically. In the case of extremely small spacing, various external disturbances are highly likely to cause a collision between the optical lens and the disc. In order to avoid the collision between the optical lens and disk, effectively eliminate the deterministic disturbance and suppress the unknown random disturbance, in this paper a multi-objective optimal output feedback controller design approach is proposed within the Q (Youla)-parameterized regulator scheme. The optimal Q parameter in the controller is obtained by solving the properly formulated linear matrix inequalities (LMIs). The experimental results show that the designed Q-parameterized controller can eliminate the influence of various disturbances and suppress the occurrence of collisions effectively.