Disturbance Modeling and Prediction of Closed-Loop Micro-Actuator Stroke Usage in Dual-Stage Hard Disk Drives

This letter presents a method to model the disturbance environment of a dual-stage hard disk drive (HDD), which is then used to predict the actuator stroke usage (i.e., the range of actuator displacement used) of a closed-loop track-following controller. In particular, a data-driven disturbance modeling approach is proposed and the stochastic interpretation of the H₂ norm is used to systematically estimate the micro-actuator (PZT) stroke usage of the HDD controller. Upper- and lower-bound models of the frequency response of the external disturbance environment are used to provide a range of possible stroke usage, which involves a data-driven 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.