Experimental modeling and feedback control of a piezobased milliactuator

In magnetic disk-drive actuators, requirements to record and read data at h igher track densities has made mechanical resonances of the servo actuator, suspension, and the head gimbal assembly a critial consideration. The appl ication of piezoelectric material in the servo actuator can be used to refi ne and accomplish track following in (extremely) high-track-density magneti c data storage by controlling the mechanical resonance modes and serving as a so-called milliactuator. In this paper the results on the modeling and c ontrol of a piezobased milliactuator are presented. The modeling is done on the basis of a least-squares curve fitting of an estimated frequency respo nse and by taking into account uncertainties in the modeled resonance modes of the servo actuator. The design and implementation of a robust controlle r provide a high bandwidth and accurate positioning of the tip of the suspe nsion and illustrate the efficiency of the piezobased milliactuator.