Mitigation of track following RRO 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) component of track-following position error signal (PES) in high TPI (Track Per Inch) hard disk drives. The harmonics of the RRO are identified and catalogized in the context of real-time RRO and written-in RRO harmonics. Combination of empirical PES measurements, review of relative analytical works, and working servo and mechanical design solution methods will be systematically discussed through this paper.