Disk drive minimizing initial seek distance after load operation
View Patent ↗A disk drive is disclosed comprising a disk comprising tracks defined by servo sectors, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors. The head is loaded over the disk during a load operation, and a radial velocity of the head is determined during the load operation. A target track is generated based on the determined radial velocity of the head, and the servo control system seeks the head to the target track.
1. A disk drive comprising:
a disk comprising tracks defined by servo sectors;
a head; and
control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors, the control circuitry operable to:
load the head over the disk during a load operation;
compute a radial velocity of the head while the head is moving over the disk during the load operation;
generate a target track using the computed radial velocity of the head; and
seek the head to the target track using the servo control system.
2. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to generate the target track based on the determined radial velocity of the head and a state trajectory profile.
3. The disk drive as recited in claim 1 , wherein the control circuitry is further operable to:
determine a current track corresponding to when the radial velocity of the head is determined; and
mainly decelerate the head from the current track to the target track.
4. The disk drive as recited in claim 1 , wherein:
the servo control system comprises a position gain and a velocity gain;
the control circuitry is operable to generate the target track based on:
VEL·VEL_GAIN/POS_GAIN
where:
VEL represents the determined radial velocity of the head;
VEL_GAIN represents the velocity gain of the servo control system; and
POS_GAIN represents the position gain of the servo control system.
5. The disk drive as recited in claim 4 , wherein the control circuitry is operable to generate the target track based on:
CUR_TRACK+VEL·VEL_GAIN/POS_GAIN
where CUR_TRACK represents a current track the head is over when the radial velocity of the head is determined.
6. The disk drive as recited in claim 5 , wherein the control circuitry is further operable to decelerate the head from the current track to the target track.
7. The disk drive as recited in claim 1 , wherein the control circuitry is operable to determine the radial velocity of the head in response to the servo sectors.
8. The disk drive as recited in claim 7 , wherein the servo control system comprises a state estimator, the control circuitry is further operable to:
load the head over the disk in a direction toward one of an inner diameter of the disk and an outer diameter of the disk; and
accelerate the head in the direction of the load in order to initialize the state estimator, wherein after initialization the state estimator is operable to determine the radial velocity of the head.
9. A method of operating a disk drive comprising a disk comprising tracks defined by servo sectors, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors, the method comprising:
loading the head over the disk during a load operation;
computing a radial velocity of the head while the head is moving over the disk during the load operation;
generating a target track using the computed radial velocity of the head; and
seeking the head to the target track using the servo control system.
10. The method as recited in claim 9 , further comprising generating the target track based on the determined radial velocity of the head and a state trajectory profile.
11. The method as recited in claim 9 , further comprising:
determining a current track corresponding to when the radial velocity of the head is determined; and
mainly decelerating the head from a current track to the target track.
12. The method as recited in claim 9 , wherein:
the servo control system comprises a position gain and a velocity gain;
the method further comprising generating the target track based on:
VEL·VEL_GAIN/POS_GAIN
where:
VEL represents the determined radial velocity of the head;
VEL_GAIN represents the velocity gain of the servo control system; and
POS_GAIN represents the position gain of the servo control system.
13. The method as recited in claim 12 , further comprising generating the target track based on:
CUR_TRACK+VEL·VEL_GAIN/POS_GAIN
where CUR_TRACK represents a current track the head is over when the radial velocity of the head is determined.
14. The method as recited in claim 13 , further comprising decelerating the head from the current track to the target track.
15. The method as recited in claim 9 , further comprising determining the radial velocity of the head in response to the servo sectors.
16. The method as recited in claim 15 , wherein the servo control system comprises a state estimator, the method further comprising:
loading the head over the disk in a direction toward one of an inner diameter of the disk and an outer diameter of the disk; and
accelerating the head in the direction of the load in order to initialize the state estimator, wherein after initialization the state estimator is operable to determine the radial velocity of the head.