US4642541A
Expired / Lapsed
US
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Track following servo for higher density disk files
Assignee: Unisys Corp
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Filing: 1983-10-20
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Granted: 1987-02-10
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Expires: 2003-10-20
Abstract
Abstract Described is a novel technique and associated arrangement for determining the noise-free value of a system parameter (e.g., head position in a disk drive) which is time variable and (usually) has a noise component as detected. The technique involves processing the (as detected) noise-including value and passing it, plus a "Time-derivative version" thereof, through "Second Order/Summing" filter means. For instance, the technique is described as particularly useful with the "track-following servo" (part of the transducer positioning means) in a high density disk file (where track density is higher than usual) to secure superior head-displacement error values which are more noise-free. Thus, (see FIG. 4), a pair of first values V a , V b are secured by detecting motor current sense voltage V i , integrating it with respect to time and passing the result through a pair of novel "second order filter" means--one band-pass (F 1 ), the other low-pass (F 2 ); while also securing a third value V c by detecting position error (signal voltage, including noise components) in the usual manner and passing it through a "second order low-pass" filter F 3 ; then algebraically summing all filter outputs to secure a relatively noise-free position error signal V xo [V xo =V a +V b +V c ]. Thus, the summing filter array gates the position-error voltage but attenuates the (mechanical) noise component (cf. filters F 2 , F 1 centered at w o --e.g., 600 Hz is satisfactory here; and having a prescribed "Quality factor" Q). Such "second order" filters are novel in themselves, and particularly as so applied (most especially as so-used in such a servo system).
Inventors
- 👤 Ashraf I. El-Sadi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:58
CPC Classifications
G; G05; G05D; G05D3/00; G05D3/12; G05D3/14; G11; G11B; G11B21/00; G11B21/02; G11B21/10; G11B21/106; G11B5/00; G11B5/48; G11B5/58; G11B5/596; G11B5/59605; G11B5/59622; H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1217
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
106 words
In a track-following servo arrangement for high-density disk files, position-error determining means operating according to a "second order summing filter" array; wherein motor current sense voltage V i is integrated and processed, by "second order band-pass" filter means F a and also by "second order low pass" filter means F b ; while a complex position error signal voltage V xi including a mechanical noise component is processed by a "second order low pass" filter means F c ; whereupon the three filter means outputs are summed by summing means to generate an improved head-position-error value as position-error voltage, V xo , relatively free of noise.
Claim 2
Dependent Claim
106 words
In a track-following servo arrangement for high-density disk files, position-error determining means operating according to a "second order summing filter" array; wherein motor current sense voltage V i is integrated and processed, by "second order band-pass" filter means F a and also by "second order low pass" filter means F b ; while a complex position error signal voltage V xi including a mechanical noise component is processed by a "second order low pass" filter means F c ; whereupon the three filter means outputs are summed by summing means to generate an improved head-position-error value as position-error voltage, V xo , relatively free of noise.
Claim 3
Dependent Claim
43 words
The combination as recited in claim 1 wherein circuit means are provided to automatically implement the "transfer function" between motor current sense voltage V i and the output V xo of the summing filters F a , F b , F c .
Claim 4
Dependent Claim
16 words
The combination as recited in claim 2 wherein the filtering is conducted at 600 Hz approximately.
Claim 5
Dependent Claim
21 words
The combination as recited in claim 3 wherein the circuit is implemented using a switching capacitor state variable filter integrated circuit.
Claim 6
Dependent Claim
133 words
A track-following servo technique for positioning head means in high-density disk files, with head position-error determining means operated according to a "second order summing filter" array; wherein positioning-motor-current sense voltage V i is integrated and processed, in parallel, by "second order band-pass" filter means F a and also by "second order low pass" filter means F b ; while a complex position error signal voltage V xi including a mechanical noise component is processed by a "second order low pass" filter means F c ; whereupon the three filter means outputs are summed by summing means to generate an improved head-position-error value as position-error voltage, V xo , relatively free of noise, whereby bandwidth is enlarged and "settling time" and "displacement error" are minimized, while yet maintaining good stability and freedom from oscillation.
Claim 7
Dependent Claim
133 words
A track-following servo technique for positioning head means in high-density disk files, with head position-error determining means operated according to a "second order summing filter" array; wherein positioning-motor-current sense voltage V i is integrated and processed, in parallel, by "second order band-pass" filter means F a and also by "second order low pass" filter means F b ; while a complex position error signal voltage V xi including a mechanical noise component is processed by a "second order low pass" filter means F c ; whereupon the three filter means outputs are summed by summing means to generate an improved head-position-error value as position-error voltage, V xo , relatively free of noise, whereby bandwidth is enlarged and "settling time" and "displacement error" are minimized, while yet maintaining good stability and freedom from oscillation.
Claim 8
Dependent Claim
43 words
The method as recited in claim 5 wherein circuit means are provided to automatically implement the "transfer function" between motor current sense voltage V i and the output V xo of the summing filters F a , F b , F c .
Claim 9
Dependent Claim
16 words
The method as recited in claim 6 wherein the filtering is conducted at about 600 Hz.
Claim 10
Dependent Claim
21 words
The method as recited in claim 7 wherein the circuit is implemented using a switching capacitor state variable filter integrated circuit.
Claim 11
Dependent Claim
123 words
A second order summing filter arrangement comprising: a time-variant signal input means adapted to accept time-variant signal input and the noise component inputs thereof; first filter means coupled to receive the output of said input means and comprising a second order low pass filter stage; second filter means adapted to apply the time-variant signals, time-differentiated, to other second order filter means; and summing means adapted to receive and sum the outputs of both filter means whereby to derive a low-noise representation of said time-variant signals without excessive attenuation; said second filter means comprising input differentiator means, plus a second order band-pass filter stage and a second order low pass filter stage, these stages coupled between said input differentiator means and said summing means.
Claim 12
Dependent Claim
123 words
A second order summing filter arrangement comprising: a time-variant signal input means adapted to accept time-variant signal input and the noise component inputs thereof; first filter means coupled to receive the output of said input means and comprising a second order low pass filter stage; second filter means adapted to apply the time-variant signals, time-differentiated, to other second order filter means; and summing means adapted to receive and sum the outputs of both filter means whereby to derive a low-noise representation of said time-variant signals without excessive attenuation; said second filter means comprising input differentiator means, plus a second order band-pass filter stage and a second order low pass filter stage, these stages coupled between said input differentiator means and said summing means.
Claim 13
Dependent Claim
148 words
In a control system for controlling automatic high speed positioning motor means which is characterized by position-error signals with significant undesirable related noise components, an improved control arrangement comprising: first input means adapted to receive the position error signals and related noise components; first second order filter means coupled to receive the output of said first input means; second input means adapted to receive motor signals reflecting current in said motor over time, these reflecting related velocity change; second second-order filter means coupled to said second input means; and summing means adapted to receive and sum the outputs of both filter means whereby to derive a low-noise representation of said time-variant signals without excessive attenuation; said second filter means comprising input differentiator means plus a second order band-pass filter stage and a second-order, low-pass filter stage, these stages coupled between said input differentiator means and said summing means.
Claim 14
Dependent Claim
148 words
In a control system for controlling automatic high speed positioning motor means which is characterized by position-error signals with significant undesirable related noise components, an improved control arrangement comprising: first input means adapted to receive the position error signals and related noise components; first second order filter means coupled to receive the output of said first input means; second input means adapted to receive motor signals reflecting current in said motor over time, these reflecting related velocity change; second second-order filter means coupled to said second input means; and summing means adapted to receive and sum the outputs of both filter means whereby to derive a low-noise representation of said time-variant signals without excessive attenuation; said second filter means comprising input differentiator means plus a second order band-pass filter stage and a second-order, low-pass filter stage, these stages coupled between said input differentiator means and said summing means.
Claim 15
Dependent Claim
181 words
A "second order summing filter" array, adapted in a track-following servo in a disk drive for a high-density disk file, for determining relatively noise-free head-position-error signals (X o ); this array being arranged and adapted to process the noise-including value X i and passing it through "second order filter" means to yield the noise-free value X o ; wherein circuit means are provided to automatically process prescribed noise-including position-error signals (X i ) and motor current sense-voltage values with second order filter means operating at a prescribed center-frequency to implement a prescribed transfer function; said circuit means comprising a first "second-order" filter means F A arranged and adapted to receive said motor current signals, and a second "second-order" filter means F B arranged and adapted to receive position-error signals X i ; and summing means arranged to receive the outputs of said first and second filter means, and summing them, to provide the relatively noise-free position-error signals (X o ); said first filter means comprising time-integrator means coupled to feed a pair of second-order filter stages connected to said summing means.
Claim 16
Dependent Claim
181 words
A "second order summing filter" array, adapted in a track-following servo in a disk drive for a high-density disk file, for determining relatively noise-free head-position-error signals (X o ); this array being arranged and adapted to process the noise-including value X i and passing it through "second order filter" means to yield the noise-free value X o ; wherein circuit means are provided to automatically process prescribed noise-including position-error signals (X i ) and motor current sense-voltage values with second order filter means operating at a prescribed center-frequency to implement a prescribed transfer function; said circuit means comprising a first "second-order" filter means F A arranged and adapted to receive said motor current signals, and a second "second-order" filter means F B arranged and adapted to receive position-error signals X i ; and summing means arranged to receive the outputs of said first and second filter means, and summing them, to provide the relatively noise-free position-error signals (X o ); said first filter means comprising time-integrator means coupled to feed a pair of second-order filter stages connected to said summing means.
Claim 17
Dependent Claim
52 words
The combination as recited in claim 11 wherein the first filter stage comprises band-pass filter and a low-pass filter; wherein the second filter means comprises a low-pass filter; and wherein the position-error signals X i comrise noise-including position-error voltage values; while the summing means generates noise-free position-error voltage signals V xo .
Claim 18
Dependent Claim
153 words
In a control system for controlling automatic high speed positioning motor means which is characterized by position-error signals with significant undesirable related noise components, including resonance and other "mechanical" noise plus "electrical" noise, an improved control arrangement comprising: a time-variant signal input means adapted to accept time-variant signal input and the noise component inputs thereof; first filter means coupled to receive the output of said input means and comprising a second order low pass filter stage; second filter means adapted to apply the time-variant signals, time-differentiated, to other second order filter means; and summing means adapted to receive and sum the outputs of both filter means whereby to derive a low-noise representation of said time-variant signals without excessive attenuation; wherein said second filter means comprises input differentiator means plus a second order band-pass filter stage and a second-order, low-pass filter stage, these stages being coupled between input differentiator means and said summing means.
Claim 19
Dependent Claim
153 words
In a control system for controlling automatic high speed positioning motor means which is characterized by position-error signals with significant undesirable related noise components, including resonance and other "mechanical" noise plus "electrical" noise, an improved control arrangement comprising: a time-variant signal input means adapted to accept time-variant signal input and the noise component inputs thereof; first filter means coupled to receive the output of said input means and comprising a second order low pass filter stage; second filter means adapted to apply the time-variant signals, time-differentiated, to other second order filter means; and summing means adapted to receive and sum the outputs of both filter means whereby to derive a low-noise representation of said time-variant signals without excessive attenuation; wherein said second filter means comprises input differentiator means plus a second order band-pass filter stage and a second-order, low-pass filter stage, these stages being coupled between input differentiator means and said summing means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-09 | 1990-08-11 | 1991-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-09 | 1994-08-11 | 1995-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-09 | 1998-08-11 | 1999-02-10 | $7700.00 | Window Closed / Lapsed |