Design and Analysis of Servo Controller in Triple-Stage Hard Disk Drive Servo System

Currently in a hard disk drive (HDD), a voice coil motor (VCM) actuator is used as the primary stage and a piezoelectric actuator is used as the secondary stage of a head positioning control in (x-y) lateral direction. To achieve the future generation high capacity HDDs, the 'Thermal Fly-height Control' (TFC) slider is employed as 'Thermal Position Control' (TPC) slider. This TPC slider is used as the tertiary stage to control the R/W head in the lateral direction. In this paper, the feasibility of using the TPC slider as a tertiary actuator in a triple-stage HDD is studied through extensive simulation analysis using MATLAB/Simulink. Besides, comparative analysis with dual-stage and single-stage hard disk drive is done. Simulation results substantiate the effectiveness of the triple-stage servo system.