고집적 HDD Head 의 정밀제어를 위한 Dual Actuator 제어기 개발

초록

An advanced magnetic storage device is expected to have around 25,000TPI(1 micro meter track pitch) by the year 2,000. The Maximum tolerable offset is about 10 percentage of the track pitch. Disk drive spinning at 7200[rpm] require a servo bandwidth of 2~3[kHz] to accomplish 25,000TPI. VCM actuator is limited to obtain desired high bandwidth due to pivot friction, magnetic hysteresis, unmodeled dynamics at high frequencies and resonance around 4~7[kHz]. Because of this problem, second actuator having high bandwidth is attached to HGA to compensated for coarse motion of VCM. And dual-stage actuator scheme, that is, VCM + micro-Actuator was presented by many disk drive engineer. VCM having low bandwidth & large stroke range is used as coarse motion control, micro-Actuator having bandwidth & very small stroke rage is mainly worked in fine motion control. In this paper, We modeled dual actuator, proposed control structure & design procedure, designed digital controller for DSP system and simulated proposed controller performance using simulation tools