1 Design and Testing of Track-Following Controllers for Dual-Stage Servo Systems with PZT Actuated Suspensions+

This paper discusses the design and testing of two track-following controllers for dual-stage servo systems in hard disk drives. The first controller is designed using the µ-synthesis multivariable robust optimal controller design methodology. The second is designed using classical single-input-single-output (SISO) frequency shaping design techniques, based on sensitivity transfer functions decoupling of the dual-stage actuator. The controllers were implemented and tested on a disk drive with a PZT actuated suspension based dual-stage servo system. The position error signal (PES) for the servo system was obtained by measuring the slider displacement using an LDV and injecting simulated track runout. In the experiment, both designs achieved a track-mis-registration (TMR) less than 10 nm