A method for reducing an estimation period for repeatable runout (RRO) errors
in
a disk drive comprising a head, a disk surface having a track partitioned by servo-wedges,
and a servo control system for controlling the movement of the head relative to
a track during revolutions of the disk. The method includes estimating the RRO
errors of the track based on a) a series of position error signal values obtained
during a current revolution of the disk surface, and b) a previous estimation of
the RRO errors of the track obtained during a previous revolution of the disk surface
and determining a differential value between a first measure of the estimated RRO
errors and a second measure of the previous estimation of RRO errors, and repeating
the estimating and determining for subsequent revolutions of the disk surface until
the determined differential value is smaller than a pre-selected threshold value.
