Patent ID: 6614618
Filing Date: 2003-09-02
Classification: G11B

Abstract:
A disk drive comprising:a plant having a disk and a transducer that periodically samples servo position information recorded on the disk at a servo sampling rate to produce an indicated position signal, and a voice coil motor adapted for moving the transducer in response to a total command effort signal; and a servo controller that generates the total command effort signal for moving the transducer from a start position to a target position, the servo controller comprising: a reference position generator that provides a reference position signal having a continuous rate of change for moving the transducer from the start position to the target position in a smoothly controlled fashion; a feedback control path that receives the reference position signal and the indicated position signal and applies a feedback command effort signal at the servo sampling rate based on a difference between the reference position signal and the indicated position signal; and a feed-forward control path that includes a multi-rate state machine and receives the reference position signal and applies a feed-forward command effort signal at a feed-forward rate that is greater than the servo sampling rate to move the transducer more closely along the shaped position profile between servo samples.