The invention relates to a disk drive and related method for improved disk rotation
rate control in the presence of seek operations. A spindle motor rotates a spindle,
supporting at least one disk with a magnetic recording surface, in response to
a motor current. The actuator radially positions a transducer head over the recording
surface. The motor is subjected to a torque load component related to the transducer
head radial position. The spindle motor controller has a feedback control loop
and a feedforward control element. The feedback control loop maintains a relatively
constant spindle rotation rate based on a difference error between a predetermined
target spindle rotation rate parameter and a measured spindle rotation rate parameter.
The feedforward control element, in conjunction with a seek operation, adjusts
the motor current based on a target head radial position with respect to an initial
head radial position.