Adaptive disturbance compensation with multi-rate synchronized sampling
View Patent ↗A media drive includes a head, a servo signal processing circuit, an actuator and a processor. The head is positioned near a data storage medium, and includes a servo element. The servo signal processing circuit is coupled to the servo element to output a position error signal. The actuator controls a position of the head relative to the data storage medium. The processor communicates with the actuator and the servo signal processing circuit. The processor provides a filtered position error signal to the actuator to compensate for a position displacement between the head and the data storage medium. The filtered position error signal includes a sum of outputs from a first compensation filter and a second compensation filter that is each applied to the position error signal output. The compensation filters attenuate disturbance frequencies that contribute to the position displacement. Each of the compensation filters has a sampling rate relating to the respective disturbance frequency. In one embodiment, the disturbance frequencies are fixed frequencies. Alternatively, the first disturbance frequency is a fixed frequency and the second disturbance frequency is a dynamic frequency. Still alternatively, the disturbance frequencies are dynamic frequencies.
1. A media drive having a data storage medium, the media drive comprising:
a head positioned near the data storage medium, the head including a servo element;
a servo signal processing circuit coupled to the servo element to output a position error signal;
an actuator that controls a position of the head relative to the data storage medium; and
a processor in communication with the actuator and the servo signal processing circuit, the processor providing a filtered position error signal to the actuator to compensate for a position displacement between the head and the data storage medium, the filtered position error signal including a sum of an output from each of a first compensation filter and a second compensation filter that are applied to the position error signal output by the servo signal processing circuit, the first compensation filter attenuating a first disturbance frequency that contributes to the position displacement, the second compensation filter attenuating a second disturbance frequency that contributes to the position displacement, each of the compensation filters having a sampling rate relating to the respective disturbance frequency, wherein each of the first disturbance frequency and the second disturbance frequency is a fixed frequency.
2. The media drive of claim 1 , wherein the sampling rate for one of the compensation filters is based on the position error signal.
3. A media drive having a data storage medium, the media drive comprising:
a head positioned near the data storage medium, the head including a servo element;
a servo signal processing circuit coupled to the servo element to output a position error signal;
an actuator that controls a position of the head relative to the data storage medium; and
a processor in communication with the actuator and the servo signal processing circuit, the processor providing a filtered position error signal to the actuator to compensate for a position displacement between the head and the data storage medium, the filtered position error signal including a sum of an output from each of a first compensation filter and a second compensation filter that are applied to the position error signal output by the servo signal processing circuit, the first compensation filter attenuating a first disturbance frequency that contributes to the position displacement, the second compensation filter attenuating a second disturbance frequency that contributes to the position displacement, each of the compensation filters having a sampling rate relating to the respective disturbance frequency, wherein the first disturbance frequency is a fixed frequency and the second disturbance frequency is a dynamic frequency.
4. The media drive of claim 3 , wherein the actuator is one of the specific sources of disturbance contributing to the position displacement.
5. The media drive of claim 4 , wherein the compensation filter for an actuator related disturbance has a fixed sampling rate.
6. The media drive of claim 3 , wherein the storage medium includes a magnetic tape and the sampling rate for one of the compensation filters is based on a tape speed of the magnetic tape.
7. The media drive of claim 3 , further including a tape reel, wherein the sampling rate for one of the compensation filters is based on a rotation rate of the tape reel.
8. The media drive of claim 7 , wherein the tape reel includes one of a supply tape reel and a take up tape reel.
9. The media drive of claim 3 , wherein each of the compensation filters is adaptively configured based on respective sampling rates to attenuate respective disturbances at the respective disturbance frequencies.
10. The media drive of claim 3 , wherein the position displacement includes lateral position displacement.
11. The media drive of claim 3 , wherein at least one of the compensation filters includes a narrow bandwidth filter.
12. The media drive of claim 3 , wherein the sampling rate for one of the compensation filters is based on the position error signal.
13. A media drive having a data storage medium, the media drive comprising:
a head positioned near the data storage medium, the head including a servo element;
a servo signal processing circuit coupled to the servo element to output a position error signal;
an actuator that controls a position of the head relative to the data storage medium; and
a processor in communication with the actuator and the servo signal processing circuit, the processor providing a filtered position error signal to the actuator to compensate for a position displacement between the head and the data storage medium, the filtered position error signal including a sum of an output from each of a first compensation filter and a second compensation filter that are applied to the position error signal output by the servo signal processing circuit, the first compensation filter attenuating a first disturbance frequency that contributes to the position displacement, the second compensation filter attenuating a second disturbance frequency that contributes to the position displacement, each of the compensation filters having a sampling rate relating to the respective disturbance frequency, wherein the sampling rate for one of the compensation filters is based on the position error signal.
14. A method for providing adaptive compensation of disturbances affecting a position of a head relative to a data storage medium, comprising the steps of:
obtaining a position error signal;
obtaining an output from a first compensation filter, the first compensation filter being based on a first sampling rate, the first compensation filter attenuating a first disturbance frequency that contributes to the position error signal, the first disturbance frequency being a fixed frequency;
obtaining an output from a second compensation filter, the second compensation filter being based on a second sampling rate that is different than the first sampling rate, the second compensation filter attenuating a second disturbance frequency that contributes to the position error signal, the second disturbance frequency being a fixed frequency; and
updating the position of the head relative to the data storage medium using a combined output of the first and second compensation filters.
15. The method of claim 14 , wherein the step of updating includes summing the output of the first and second compensation filters.
16. The method of claim 14 , wherein the first disturbance frequency is caused by a mechanical disturbance.
17. The method of claim 14 , wherein one of the sampling rates is based on a tape speed of a magnetic tape of a tape drive.
18. The method of claim 14 , wherein one of the compensation filters includes a narrow bandwidth filter.
19. A method for providing adaptive compensation of disturbances affecting a position of a head relative to a data storage medium, comprising the steps of:
obtaining a position error signal;
obtaining an output from a first compensation filter, the first compensation filter being based on a first sampling rate, the first compensation filter attenuating a first disturbance frequency that contributes to the position error signal, the first disturbance frequency being a dynamic frequency;
obtaining an output from a second compensation filter, the second compensation filter being based on a second sampling rate that is different than the first sampling rate, the second compensation filter attenuating a second disturbance frequency that contributes to the position error signal, the second disturbance frequency being a dynamic frequency; and
updating the position of the head relative to the data storage medium using a combined output of the first and second compensation filters;
wherein one of the disturbance frequencies is based on a reel rotation disturbance from a reel of a media drive.
20. The method of claim 19 , wherein the first disturbance frequency is based on a mechanical disturbance.
21. The method of claim 19 , wherein the reel rotation disturbance is caused by one of a supply reel and a take up reel.
22. The method of claim 19 , wherein one of the sampling rates is based on one of a take up reel rotation rate and a supply reel rotation rate.
23. The method of claim 19 , wherein one of the sampling rates is based on a positioning of a magnetic tape relative to the head of a tape drive.
24. A method for providing adaptive compensation of disturbances affecting a position of a head relative to a data storage medium, comprising the steps of:
obtaining a position error signal;
obtaining an output from a first compensation filter, the first compensation filter being based on a first sampling rate, the first compensation filter attenuating a first disturbance frequency that contributes to the position error signal;
obtaining an output from a second compensation filter, the second compensation filter being based on a second sampling rate that is different than the first sampling rate, the second compensation filter attenuating a second disturbance frequency that contributes to the position error signal; and
updating the position of the head relative to the data storage medium using a combined output of the first and second compensation filters;
wherein one of the sampling rates is based on a positioning of a magnetic tape relative to the head of a tape drive.