Discrete-time sliding mode repetitive control for track-following of optical disk drives

The disturbances acting on the track-following servo system of an optical disk drive inherently contain significant periodic components that cause track error of a periodic nature. In this paper, discrete-time sliding mode repetitive control (DSMRC) was developed, which can reject such disturbances. The developed approach ensures the robustness of the sliding mode dynamics to parameter uncertainties and exogenous disturbances and the complete rejection of the periodic disturbance component. The satisfied simulation results as well as the experimental results using an optical disk drive are given to illustrate the validity of the proposed method.