Design of a fast and precise head positioning servo control system for HDDS

Abstract

A new parameterized controller is designed for a hard disk drive (HDD) head positioning servo system which currently uses the voice coil motor as its servo mechanism. The controller aims to meet the tougher performance specification in HDD head positioning. Simulation and experiment studies have been carried out. In the design of the controller, a so-called composite nonlinear feedback (CNF) control technology is adopted, which can improve the transient performance, and achieve fast response and low overshoot at the same time. A reduced-order observer is also designed to estimate and then compensate the unknown disturbance in the servo system. This effectively removes the static tracking error that would be caused by disturbances without compensation. Simulation and experimental results verify that the HDD head is capable of fast and precise positioning on target tracks. The parameterized design of the servo controller can be easily generalized to other servo systems.