Dual-stage servo with on-slider PZT microactuator for hard disk drives

A dual-stage servo system with an on-slider piezoelectric (PZT) microactuator is developed for future high-density hard disk drives. The parallel control scheme is used in servo design with considerations over the stroke limitation and the hysteresis of the microactuator. Experimental results on a spin-stand with a laser Doppler vibrometer as the position sensor demonstrate that the system has a servo bandwidth higher than 4 kHz and has disturbance rejection capability up to near 5 kHz.