Patent ID: 7050258

Claim:
A disk drive having improved disk rotation rate control in the presence of seek operations, comprising: a spindle for rotating at least one disk having at least one recording surface, each recording surface having tracks at discrete radial locations; an actuator for radially positioning, over each recording surface, a transducer head; a spindle motor for rotating the spindle in response to a motor current, the motor being subjected to a torque load component related to a transducer head radial position; and a spindle motor controller for controlling the motor current, the spindle motor controller having: a feedback control loop for maintaining a relatively constant spindle rotation rate based on a difference error, and a feedforward control element that, in conjunction with a seek operation from an initial head radial position to a target head radial position, adjusts the motor current based on the target head radial position with respect to the initial head radial position, to lessen the effects of the torque load component, wherein the motor current is adjusted by an amount based on a difference between a first ascertained motor current corresponding to the initial head radial position and a second ascertained motor current corresponding to the target head radial position and each of the first ascertained motor current and the second ascertained motor current is ascertained based on an interpolation using motor current measurements corresponding to at least first and second calibration positions.