High-bandwidth HDD tracking servo by a moving-slider micro-actuator

This paper describes a micro-actuator for high-bandwidth tracking servo, where a micro-actuator is attached between slider and suspension, and moves the slider relative to the suspension. The micro-actuator frequency response measurement proved that this micro-actuator can be modeled as an ideal spring-mass-damper system up to 80 kHz, so that very high bandwidth servo system can be easily designed. The maximum servo bandwidth of 6.4 kHz was achieved in a drive level experiment, which is the highest bandwidth ever demonstrated as a drive level. A rapid step response time of 0.2 mS for 0.6 /spl mu/m step was also achieved. The experimental bandwidth was not limited by the micro-actuator's resonance mode, but the saturation of the micro-actuator driver.