Mitigation of Track Following Repeatable Runout in High TPI Hard Disk Drives Through Servo and Mechanical Designs

Servo and mechanical approaches are presented in this paper with a view to minimize repeatable runout (RRO) components of track-following position error signal (PES) in high Track Per Inch (TPI) hard disk drives. Harmonics of the RRO are identified and classified in the context of real-time RRO and written-in RRO harmonics. Combination of experimental PES measurements, relative analytical models, and practical servo and mechanical design methods is presented and systematically discussed in this paper.