A system includes a current control module that supplies current to a
voice coil motor during a first period to rotate an actuator arm in a
first rotational direction, that discharges the current from the voice
coil motor after the first period, and that generates a control signal a
predetermined period after the current is discharged. A back
electromagnetic force (bemf) module generates a bemf signal in response
to the control signal. A speed control module determines a speed of the
actuator arm based on the bemf signal.