Disk drive with feed-forward control path that receives a reference position signal to apply a feed-forward command effort at a rate greater than a servo sampling rate

摘要

Disclosed is a disk drive having a plant with a moveable transducer and a servo controller that more precisely controls the transducer during short to medium seeks by producing a multi-rate feed-forward command effort signal. The servo controller includes a reference position generator that provides a reference position signal that varies as a function of time along a shaped position profile for moving the transducer from a start position to a target position in a smoothly controlled fashion, a feed-forward control path that 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 actuator more closely along the shaped position profile between servo samples; and 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 to make minor corrections to error remaining after application of prior feed-forward command effort signals.