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US 7,253,987 B1Granted
Disturbance signal reduction in servo systems
AssigneeMaxtor Corporation
InventorsDavid Hyunchul Shim, Jong-Min Lin, Lin Guo
Life of this patent
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Abstract
A servo system includes a first member and a second member that is positionable relative to the first member. A position error signal causes the second member to be positioned at a desired location relative to the first member. The position error signal includes a position error due to a disturbance in the servo system, and the position error is reduced by attenuation of a disturbance signal as a non-linear function of the amplitude of the disturbance signal.
Claims100
A method for operating a servo system including a first member and a second member that is positionable relative to the first member, the method comprising:
- generating a position error signal to cause the second member to be positioned at a desired location relative to the first member;
- and
- reducing a position error in the position error signal by non-linear attenuation, wherein the position error is due to a disturbance in the servo system, the disturbance generates a disturbance signal in the position error signal, reducing the position error includes selectively adjusting the disturbance signal as a function of the amplitude of the disturbance signal and the function has a first selectable parameter N representing a threshold level for non-linear signal level adjustment such that adjusting the disturbance signal is a non-linear function of the ratio of the amplitude of the disturbance signal and the parameter N.
A servo system comprising:
- a first member;
- a second member positionable relative to the first member;
- and
- a control loop including:
- a servo controller that generates a position error signal to cause the second member to be positioned at a desired location relative to the first member;
- and
- an attenuator that selectively reduces a position error in the position error signal by non-linear filtering, wherein the position error is due to a disturbance in the servo system, the disturbance generates a disturbance signal in the position error signal, the attenuator includes a gain controller that adjusts the disturbance signal as a non-linear function of the amplitude of the disturbance signal and the function has a first selectable parameter N representing a threshold level for non-linear signal level adjustment such that the gain controller adjusts the disturbance signal as a non-linear function of the ratio of the amplitude of the disturbance signal and the parameter N.
4 more elements
A disk drive comprising:
- a disk for storing information in tracks;
- a transducer positionable over the tracks for reading information therefrom;
- and
- a control loop including:
- a servo controller that generates a position error signal to cause the transducer to be positioned relative to a desired track on the disk;
- and
- an attenuator that selectively reduces a position error in the position error signal by non-linear attenuation, wherein the position error is due to a disturbance in the disk drive, the disturbance generates a disturbance signal in the position error signal, the attenuator includes a gain controller that adjusts the disturbance signal as a non-linear function of the amplitude of the disturbance signal and the function has a first selectable parameter N representing a threshold level for non-linear signal adjustment such that the gain controller adjusts the disturbance signal as a non-linear function of the ratio of the amplitude of the disturbance signal and the parameter N.
4 more elements
A method for operating a servo system including a first member and a second member that is positionable relative to the first member, the method comprising:
- generating a position error signal to cause the second member to be positioned at a desired location relative to the first member;
- and
- reducing a position error in the position error signal by non-linear attenuation, wherein the position error is due to a disturbance in the servo system, the disturbance generates a disturbance signal in the position error signal and reducing the position error includes selectively adjusting the disturbance signal as an odd function of the amplitude of the disturbance signal.
A method for operating a servo system including a first member and a second member that is positionable relative to the first member, the method comprising:
- generating a position error signal to cause the second member to be positioned at a desired location relative to the first member;
- reducing a position error in the position error signal by non-linear attenuation, wherein the position error is due to a disturbance in the servo system and the disturbance generates a disturbance signal in the position error signal;
- determining the frequency band and amplitude range of the disturbance signal;
- filtering the position error signal using a peak filter based on the frequency band and amplitude range of the disturbance signal to selectively pass the disturbance signal;
- generating a correction signal having an amplitude that varies as a non-linear function of the amplitude of the disturbance signal;
- and
- combining the correction signal with the position error signal to generate a corrected position error signal, thereby reducing the position error in the position error signal.
4 more elements
A servo system comprising:
- a first member;
- a second member positionable relative to the first member;
- and
- a control loop including:
- a servo controller that generates a position error signal to cause the second member to be positioned at a desired location relative to the first member;
- and
- an attenuator that selectively reduces a position error in the position error signal by non-linear filtering, wherein the position error is due to a disturbance in the servo system, the disturbance generates a disturbance signal in the position error signal and the attenuator includes a gain controller that adjusts the disturbance signal as a non-linear odd function of the amplitude of the disturbance signal.
4 more elements
A servo system comprising:
- a first member;
- a second member positionable relative to the first member;
- and
- a control loop including:
- a servo controller that generates a position error signal to cause the second member to be positioned at a desired location relative to the first member;
- and
- an attenuator that selectively reduces a position error in the position error signal by non-linear filtering, wherein the position error is due to a disturbance in the servo system, the disturbance generates a disturbance signal in the position error signal and the attenuator includes:
- a peak filter that filters the position error signal based on the frequency band and amplitude range of the disturbance signal to selectively pass the disturbance signal;
- a gain controller that generates a correction signal having an amplitude that varies as a non-linear function of the amplitude of the disturbance signal;
- and
- a combiner that combines the correction signal with the position error signal to generate a corrected position error signal.
8 more elements
A servo system comprising:
- a first member;
- a second member positionable relative to the first member;
- and
- a control loop including:
- a servo controller that generates a position error signal to cause the second member to be positioned at a desired location relative to the first member;
- and
- an attenuator that selectively reduces a position error in the position error signal by non-linear filtering, wherein the position error is due to a disturbance in the servo system, the disturbance generates a disturbance signal in the position error signal and the attenuator includes:
- a filter that filters the position error signal to selectively pass the disturbance signal;
- a gain controller that generates a correction signal having an amplitude that varies as a non-linear function of the amplitude of the disturbance signal;
- a combiner that combines the correction signal with the position error signal to generate a corrected position error signal;
- and
- a saturation controller that limits the corrected position error signal to preserve servo loop stability as the correction signal increases above a threshold.
9 more elements
A servo system comprising:
- a first member;
- a second member positionable relative to the first member;
- and
- a control loop including:
- a servo controller that generates a position error signal to cause the second member to be positioned at a desired location relative to the first member;
- and
- an attenuator that selectively reduces a position error in the position error signal by non-linear filtering, wherein the position error is due to a disturbance in the servo system, the disturbance generates a disturbance signal in the position error signal and the attenuator includes:
- a filter that filters the position error signal to selectively pass the disturbance signal;
- a gain controller that generates a correction signal having an amplitude that varies as a non-linear function of the amplitude of the disturbance signal;
- a combiner that combines the correction signal with the position error signal to generate a corrected position error signal;
- and
- a deadzone controller that filters the output signal of the attenuator to preserve servo loop stability as the gain controller output signal decreases below a threshold.
9 more elements
A disk drive comprising:
- a disk for storing information in tracks;
- a transducer positionable over the tracks for reading information therefrom;
- and
- a control loop including:
- a servo controller that generates a position error signal to cause the transducer to be positioned relative to a desired track on the disk;
- and
- an attenuator that selectively reduces a position error in the position error signal by non-linear attenuation, wherein the position error is due to a disturbance in the disk drive, the disturbance generates a disturbance signal in the position error signal and the attenuator includes a gain controller that adjusts the disturbance signal as a non-linear odd function of the amplitude of the disturbance signal.
4 more elements
A disk drive comprising:
- a disk for storing information in tracks;
- a transducer positionable over the tracks for reading information therefrom;
- and
- a control loop including:
- a servo controller that generates a position error signal to cause the transducer to be positioned relative to a desired track on the disk;
- and
- an attenuator that selectively reduces a position error in the position error signal by non-linear attenuation, wherein the position error is due to a disturbance in the disk drive, the disturbance generates a disturbance signal in the position error signal and the attenuator includes:
- a peak filter that filters the position error signal based on the frequency band and amplitude range of the disturbance signal to selectively pass the disturbance signal;
- a gain controller that generates a correction signal having an amplitude that varies as a non-linear function of the amplitude of the disturbance signal;
- and
- a combiner that combines the correction signal with the position error signal to generate a corrected position error signal.
8 more elements
A disk drive comprising:
- a disk;
- a transducer for reading from and writing to the disk;
- a servo controller that generates a position error signal that includes a disturbance signal, wherein the disturbance signal is due to a disturbance and causes a position error in the position error signal;
- and
- an attenuator that includes a band pass filter, a gain controller and a combiner, wherein the band pass filter generates the disturbance signal by narrow-band filtering the position error signal, the gain controller generates a correction signal by applying a non-linear function to the disturbance signal, the function has a first selectable parameter N representing a threshold level for non-linear signal adjustment to adjust the disturbance signal as a non-linear function of the ratio of the amplitude of the disturbance signal and the parameter N, the combiner generates a corrected position error signal by summing the position error signal and the correction signal, the corrected position error signal has less of the position error than the position error signal has and the transducer is positioned relative to the disk by the corrected position error signal.
2 more elements
A disk drive comprising:
- a disk;
- a transducer for reading from and writing to the disk;
- a servo controller that generates a position error signal that includes a disturbance signal, wherein the disturbance signal is due to a disturbance and causes a position error in the position error signal;
- and
- an attenuator that includes a band pass filter, a gain controller and a combiner, wherein the band pass filter generates the disturbance signal by narrow-band filtering the position error signal, the gain controller generates a correction signal by applying a non-linear odd function to the disturbance signal, the combiner generates a corrected position error signal by summing the position error signal and the correction signal, the corrected position error signal has less of the position error than the position error signal has and the transducer is positioned relative to the disk by the corrected position error signal.
2 more elements
A disk drive comprising:
- a disk;
- a transducer for reading from and writing to the disk;
- a servo controller that generates a position error signal that includes a disturbance signal, wherein the disturbance signal is due to a disturbance and causes a position error in the position error signal;
- and
- an attenuator that includes a peak filter, a gain controller and a combiner, wherein the peak filter generates the disturbance signal by narrow-band filtering the position error signal based on the frequency band and amplitude range of the disturbance signal, the gain controller generates a correction signal by applying a non-linear function to the disturbance signal, the combiner generates a corrected position error signal by summing the position error signal and the correction signal, the corrected position error signal has less of the position error than the position error signal has and the transducer is positioned relative to the disk by the corrected position error signal.
2 more elements
A disk drive comprising:
- a disk;
- a transducer for reading from and writing to the disk;
- a servo controller that generates a position error signal that includes a disturbance signal, wherein the disturbance signal is due to a disturbance and causes a position error in the position error signal;
- and
- an attenuator that includes a band pass filter, a gain controller, a saturation controller and a combiner, wherein the band pass filter generates the disturbance signal by narrow-band filtering the position error signal, the gain controller generates a correction signal by applying a non-linear function to the disturbance signal, the saturation controller clips the correction signal if the amplitude of the correction signal is above a threshold, the combiner generates a corrected position error signal by summing the position error signal and the correction signal, the corrected position error signal has less of the position error than the position error signal has and the transducer is positioned relative to the disk by the corrected position error signal.
2 more elements
A disk drive comprising:
- a disk;
- a transducer for reading from and writing to the disk;
- a servo controller that generates a position error signal that includes a disturbance signal, wherein the disturbance signal is due to a disturbance and causes a position error in the position error signal;
- and
- an attenuator that includes a band pass filter, a gain controller, a deadzone controller and a combiner, wherein the band pass filter generates the disturbance signal by narrow-band filtering the position error signal, the gain controller generates a correction signal by applying a non-linear function to the disturbance signal, the deadzone controller blocks the correction signal if the amplitude of the correction signal is below a threshold, the combiner generates a corrected position error signal by summing the position error signal and the correction signal, the corrected position error signal has less of the position error than the position error signal has and the transducer is positioned relative to the disk by the corrected position error signal.
2 more elements
Dependencies are inferred from the claim text.