Disk drive with improved spin-up control
A disk drive is disclosed comprising a head actuated over a disk, and a spindle motor operable to rotate the disk. The disk drive comprises control circuitry configured to a rotation speed of the spindle motor, generate a gain as a function of the measured rotation speed, wherein the function comprises a polynomial having a degree greater than one, and spin-up the spindle motor based on the gain.
1. A disk drive comprising:
a head actuated over a disk;
a spindle motor operable to rotate the disk; and
control circuitry operable to:
measure a rotation speed of the spindle motor;
generate a gain as a function of the measured rotation speed, wherein the function comprises a polynomial having a degree greater than one; and
spin-up the spindle motor based on the gain.
2. The disk drive as recited in claim 1 , wherein the gain comprises a feedback gain operable to amplify a feedback error signal based on a difference between the measured rotation speed and a target rotation speed.
3. The disk drive as recited in claim 1 , wherein the polynomial consists of a degree of two.
4. A method of operating a disk drive comprising a head actuated over a disk, and a spindle motor operable to rotate the disk, the method comprising:
measuring a rotation speed of the spindle motor;
generating a gain as a function of the measured rotation speed, wherein the function comprises a polynomial having a degree greater than one; and
spinning up the spindle motor based on the gain.
5. The method as recited in claim 4 , wherein the gain comprises a feedback gain operable to amplify a feedback error signal based on a difference between the measured rotation speed and a target rotation speed.
6. The method as recited in claim 4 , wherein the polynomial consists of a degree of two.
7. Control circuitry for use in a disk drive comprising a head actuated over a disk, and a spindle motor operable to rotate the disk, wherein the control circuitry is operable to:
measure a rotation speed of the spindle motor;
generate a gain as a function of the measured rotation speed, wherein the function comprises a polynomial having a degree greater than one; and
spin-up the spindle motor based on the gain.
8. The control circuitry as recited in claim 7 , wherein the gain comprises a feedback gain operable to amplify a feedback error signal based on a difference between the measured rotation speed and a target rotation speed.
9. The control circuitry as recited in claim 8 , wherein the polynomial consists of a degree of two.