Enhancing the tracking performance in optical storage systems using a disturbance compensator

In this paper, we consider an adaptive disturbance compensation method to enhance the tracking performance in optical storage systems. To eliminate the unknown reference, we formulate the tracking problem into a regulation problem with unknown disturbance. Then, based on a simple disturbance observer that effectively estimates the low frequency components of disturbance, the feedforward compensation is added to the conventional feedback control. The robustness issue and the sensitivity analysis are given to illustrate the effectiveness of the proposed approach. Finally, the method is verified by experiments in an optical storage device subject to excessive eccentricity.