Synthesis of robust servo system with repetitive controller and its application to disk file systems

Abstract

In this study control of two-degree-of-freedom-(2 DOF) robust servo system combined with repetitive controller is proposed for the control of a disk file head-positioning system. For the control of the disk file system both the tracking performance and robust stability are mainly required. In addition the periodic disturbance produced by disk rotation should be considered. The excellent tracking performance and robust stability can be attained by the 2 DOF robust servo system and the adverse effect of the periodic disturbance can be reduced by the repetitive controller. In order to reduce the adverse effects of the periodic disturbance while keeping the excellent closed loop performance the 2 DOF is combined with the repetitive control. Proposed control system is applied to the forcussing control system of the CD-R experimental system. Experimental results show the usefulness and effectiveness of the proposed control system.