Adaptive inverse control for the pickup head flying height of near-field optical diskdrives

Abstract

Near-field optical disk drives represent a promising technique for optical data recording toachieve an even larger storage density and capacity than DVD-ROM and Blu-ray diskdrives. To realize near-field optics, unlike conventional optical disk drives, a flying pickuphead is required. In this study, the pickup head consists of a suspension arm, a sliderand a bimorph piezoelectric bender between the suspension arm and the slider.The dynamic model of the pickup head is identified using measurement, but thewhole dynamics including both pickup head and interface dynamics between thedisk and slider is unmodeled. Adaptive inverse control of robustness is developedto track the vibratory deformation of rotating optical disks, so that the flyingheight of a pickup head can remain stable in the presence of modeling error.Experimental results demonstrate that using the proposed method the pickuphead can not only track disk deformation but also maintain the flying height.