Abstract
In this paper, we propose a quadruple-stage actuator system for a magnetic-head positioning system in hard disk drives (HDDs). The quadruple-stage actuator system consists of a voice coil motor, a milli actuator with two piezoelectric (PZT) elements, a micro actuator with two PZT elements, and a thermal actuator. The milli actuator is the first generation of a secondary actuator for a dual- stage actuator in the HDDs and moves a sway mode of a suspension. The micro actuator is the second generation of the secondary actuator for the dual-stage actuator in the HDDs and moves a yaw mode of the suspension. The thermal actuator is a new actuator for future HDDs and moves position of read/write elements in a horizontal direction with thermal expansion. The simulation results of sensitivity functions show that the proposed quadruple-stage actuator system can improve a performance of disturbance compensation by about 6 dB from that of a triple-stage actuator system.
