Data storage device calibrating fine actuator by ramping disturbance to attenuate servo transient
A data storage device is disclosed comprising a first plurality of heads actuated over a first subset of disk surfaces by a first servo control loop comprising a first coarse actuator and a first fine actuator, and a second plurality of heads actuated over a second subset of the disk surfaces by a second servo control loop comprising a second coarse actuator and a second fine actuator. A plurality of access commands are received, wherein each access command is associated with one of the heads. While executing a first access command using the first servo control loop, a disturbance is ramped while injecting the disturbance into the second servo control loop, and the second fine actuator is calibrated based on the disturbance.
1. A data storage device comprising:
a plurality of disk surfaces;
a first plurality of heads actuated over a first subset of the disk surfaces by a first servo control loop comprising a first coarse actuator and a first fine actuator;
a second plurality of heads actuated over a second subset of the disk surfaces by a second servo control loop comprising a second coarse actuator and a second fine actuator; and
control circuitry configured to:
receive a plurality of access commands, wherein each access command is associated with one of the heads;
while executing a first access command using the first servo control loop:
ramp a disturbance while injecting the disturbance into the second servo control loop; and
calibrate the second fine actuator based on the disturbance.
2. The data storage device as recited in claim 1 , wherein the disturbance consists of a sinusoid.
3. The data storage device as recited in claim 2 , wherein the control circuitry is further configured to ramp the disturbance by ramping an amplitude of the sinusoid.
4. The data storage device as recited in claim 1 , wherein ramping the disturbance attenuates a transient in the first servo control loop while executing the first access command.
5. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to calibrate a slope of the ramp.
6. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to adapt a slope of the ramp based on a performance of the first servo control loop.
7. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to:
ramp the disturbance at a first rate when the first access command is a read command; and
ramp the disturbance at a second rate slower than the first rate when the first access command is a write command.
8. A data storage device comprising:
a plurality of disk surfaces;
a first plurality of heads actuated over a first subset of the disk surfaces by a first servo control loop comprising a first coarse actuator and a first fine actuator;
a second plurality of heads actuated over a second subset of the disk surfaces by a second servo control loop comprising a second coarse actuator and a second fine actuator; and
control circuitry configured to:
receive a plurality of access commands, wherein each access command is associated with one of the heads;
while executing a first access command using the first servo control loop:
modify a disturbance while injecting the disturbance into the second servo control loop, wherein modifying the disturbance attenuates a transient in the first servo control loop; and
calibrate the second fine actuator based on the disturbance.
9. The data storage device as recited in claim 8 , wherein the control circuitry is further configured to modify the disturbance by ramping the disturbance.
10. The data storage device as recited in claim 9 , wherein the disturbance consists of a sinusoid.
11. The data storage device as recited in claim 10 , wherein the control circuitry is further configured to ramp the disturbance by ramping an amplitude of the sinusoid.
12. The data storage device as recited in claim 9 , wherein the control circuitry is further configured to calibrate a slope of the ramp.
13. The data storage device as recited in claim 9 , wherein the control circuitry is further configured to adapt a slope of the ramp based on a performance of the first servo control loop.
14. The data storage device as recited in claim 9 , wherein the control circuitry is further configured to:
ramp the disturbance at a first rate when the first access command is a read command; and
ramp the disturbance at a second rate slower than the first rate when the first access command is a write command.
15. A data storage device comprising:
a plurality of disk surfaces;
a first plurality of heads actuated over a first subset of the disk surfaces by a first servo control loop comprising a first coarse actuator and a first fine actuator;
a second plurality of heads actuated over a second subset of the disk surfaces by a second servo control loop comprising a second coarse actuator and a second fine actuator; and
a means for receiving a plurality of access commands, wherein each access command is associated with one of the heads;
while executing a first access command using the first servo control loop:
a means for ramping a disturbance while injecting the disturbance into the second servo control loop; and
a means for calibrating the second fine actuator based on the disturbance.
16. The data storage device as recited in claim 15 , wherein the disturbance consists of a sinusoid.
17. The data storage device as recited in claim 16 , wherein the means for ramping ramps an amplitude of the sinusoid.
18. The data storage device as recited in claim 15 , wherein ramping the disturbance attenuates a transient in the first servo control loop while executing the first access command.
19. The data storage device as recited in claim 15 , further comprising a means for adjusting a slope of the ramp.
20. The data storage device as recited in claim 15 , wherein the means for ramping:
ramps the disturbance at a first rate when the first access command is a read command; and
ramps the disturbance at a second rate slower than the first rate when the first access command is a write command.