A close tracking algorithm for a tracking servo system is disclosed. The track
crossing rate of an optical pick-up unit positioned over an optical media is determined.
When the track crossing rate is below a threshold value, then a tracking servo
algorithm is enabled. The tracking servo algorithm provides control signals to
control an actuator arm that controls the position of the optical pick-up unit
over the tracks of the optical media. In some embodiments, the track crossing rate
can be determined by monitoring the zero crossings of a tracking error signal derived
from optical signals measured in the optical pick-up unit.
