A Linear Time-Varying Control Scheme and Its Application to a Hard Disk Drive Servo System

A novel linear time-varying (LTV) control scheme is developed to perform short/mid-span seeking and track- following. This new scheme uses the concept behind the conventional composite nonlinear feedback (CNF) scheme to exhibit fast and smooth seeking. Having two nonlinear time components that are independent of seek length to adjust the feedback gain, the proposed scheme displays a notably better performance robustness against variations in seek length during short/mid-span seeking as well as 25.3% more head positioning accuracy during track-following over the conventional CNF control.