Comparison of suspension-based and slider-based microactuators for track following performance

Recent increases in the hard disk drive track density have placed stringent requirements on the control of the head position relative to the track center during reading and writing, which is also referred to as track following. In industry and academia several different microactuators have been proposed and used to increase the track following capacity of hard disk drives. This work compares suspension-based and slider-based microactuators for track following performance. In particular, a large stroke linear MEMS actuator, a suspension-based PZT actuator and a collocated PZT transducer actuator are compared. Dynamic models of the microactuators have been derived based on data presented in the literature. An open-loop disturbance spectrum is generated for a suspension-based microactuated suspension on a high performance test spinstand. Open-loop disturbance spectra for the slider-based linear MEMS microactuator and collocated transducer PZT microactuator are developed using the open-loop disturbance spectrum of the suspension based microactuator in conjunction with the dynamic model of each microactuator. Closed-loop track following controllers are designed for each case and closed-loop projections are carried out. Pros and cons of each microactuator are discussed from disturbance spectrum and controller design points of view.