PIVOT NONLINEARITY IN DISK-DRIVE ROTARY ACTUATOR - MEASUREMENT AND MODELING

As track density increases, the effects of nonlinearity in the pivot b earing of the hard disk drive on the servo performance are becoming mo re important. Recently, increasing attention is given to more precise experimental observation and modeling of pivot nonlinearity to achieve improved servo control. In this paper, we propose a new model that pr edicts improved pivot nonlinearity over existing ''preload + two slope '' models in matching simulation and experimental results in both the time and frequency domains. Experimental measurements are carried out to validate and identify the specific nonlinearities present in the pi vot bearing when it is in fine motion.