Optimal control issues related to the hard disk drive servo systems

Abstract

The magnetic hard disk drive (HDD) has seen a 100% annual growth rate in the past few years. The improved servo control is the most cost-effective way to support this trend. This thesis presents some new control designs for HDD servo systems. Two kinds of control methods have been studied and implemented. The robust and perfect tracking (RPT) design is studied in both the continuous-time and discrete-time domains. The H2 optimal control has been studied to achieve the highest tracking accuracy. Both RPT control and H2 optimal control have been applied to both single-stage actuator system and dual-stage actuator system. All the designs presented in this thesis show superior performance over the conventional control designs in hard disk drives.