RRO compensation of hard disk drives with RPTC considering correlation of adjacent tracks

This paper presents an improvement method of repetitive controller based on perfect tracking control (PTC) in order to reject variance repeatable runout (RRO) of hard disk drive. Authorspsila group proposed the repetitive PTC (RPTC) with switching mechanism. RPTC is constructed by using periodic signal generator (PSG) and PTC. The PSG works to make feedforward signal from the periodic disturbance and the PTC generates control input to cancel the periodic error in steady-state. However, we have not considered the difference of RRO between tracks. This paper proposes a re-learning scheme considering correlation of adjacent tracks. Finally, the advantages of RPTC using proposed scheme are demonstrated through simulations and experimented at HDD equipment.