VIBRATION SERVO CONTROL DESIGN FOR ACTUATOR'S MECHANICAL RESONANT MODES IN HARD DISK DRIVES

Abstract

We developed a design method that can suppress the vibration from high-order resonant modes in a head-positioning system of a hard disk drive. We used the vector locus of an open-loop transfer function to design both the controller and the structure simultaneously. Application of the method to an actual hard disk drive showed that positioning accuracy under high-order resonant modes can be improved by 55%. In addition, when all resonances are in-phase, the developed method can suppress vibrations caused by all mechanical resonances. We concluded that the method can design a control system with high robustness and good following control performance.