Dual stage servo systems using VCM and PZT actuator have rapidly applied in commercial Hard Disk Drives after long time development stage. We measure mechanical frequency response of VCM and PZT actuator in commercial HDDs, we make whole dual stage servo model using by the measured mechanical characteristics. Using this model, we investigate the optimum design of total system, and will discuss the positioning accuracy improvement. We also show the stabilizing effect of PZT servo system.
