High-bandwidth HDD Tracking Servo by a Moving-slider Micro-actuator

This paper describes a micro-actuator for high-bandwidth tracking servo, where a microactuator 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 βm 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. ©1999 IEEE.