Disturbance Modeling and Prediction of ClosedLoop MicroActuator Stroke Usage in DualStage Hard Disk Drives

Abstract

This letter presents a method to model the disturbance environment of a dualstage hard disk drive (HDD), which is then used to predict the actuator stroke usage (i.e., the range of actuator displacement used) of a closedloop trackfollowing controller. In particular, a datadriven disturbance modeling approach is proposed and the stochastic interpretation of the H2 norm is used to systematically estimate the microactuator (PZT) stroke usage of the HDD controller. Upper and lowerbound models of the frequency response of the external disturbance environment are used to provide a range of possible stroke usage, which involves a datadriven calibration process. The accuracy of the prediction model is validated in experiments with a controller that differs from the controllers in the calibration data set.