US5610848A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Robust resonance reduction using staggered posicast filters
Assignee: The AT&T MVPD Group LLC
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Filing: 1994-05-13
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Granted: 1997-03-11
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Expires: 2014-05-13
Abstract
Abstract A method for filtering actuator commands for a satellite control system to reduce resonant mode excitation despite uncertain knowledge of the resonance frequencies, due to parameter variations, nonlinearities, and the like. The present method filters the actuator commands with staggered proportional plus delay (posicast) filters having distinct delay values, chosen to provide a desired resonance attenuation over a resonance uncertainty range. The present method may be extended to filter multiple resonances by cascading the staggered filters for each resonance. The present invention has wide application, such as in spacecraft precession and translation maneuvers, as well as gimbaled payload stepping. A particular advantage of the present invention is its direct applicability to fixed-amplitude actuators (such as thrusters and stepper motors), and reduced excitation of resonances at frequencies above those of primary concern.
Inventors
- 👤 Richard A. Fowell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:34
CPC Classifications
B; B64; B64G; B64G1/00; B64G1/22; B64G1/24; B64G1/38; B64G1/244; B64G1/28; B64G1/285
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
131 words
A method for processing actuator commands applied to actuators of a satellite system to reduce resonant mode excitation in the satellite system for a mode of variable or uncertain frequency, said method comprising the steps of: generating actuator commands that are to be applied to actuators of the satellite system; filtering the actuator commands with a plurality of cascaded staggered proportional plus delay filters having delay values that are distinct, yet close enough together so that the frequency response between first zeros of the proportional plus delay filters provides a predetermined level of resonance reduction over at least the frequency uncertainty range of the mode, and such that the filter impulse response has a set of equal impulses; and applying the filtered actuator commands to the actuators of the satellite system.
Claim 2
Independent Claim
131 words
A method for processing actuator commands applied to actuators of a satellite system to reduce resonant mode excitation in the satellite system for a mode of variable or uncertain frequency, said method comprising the steps of: generating actuator commands that are to be applied to actuators of the satellite system; filtering the actuator commands with a plurality of cascaded staggered proportional plus delay filters having delay values that are distinct, yet close enough together so that the frequency response between first zeros of the proportional plus delay filters provides a predetermined level of resonance reduction over at least the frequency uncertainty range of the mode, and such that the filter impulse response has a set of equal impulses; and applying the filtered actuator commands to the actuators of the satellite system.
Claim 3
Dependent Claim
57 words
The method of claim 1 wherein the actuator commands further comprise movement commands and wherein the filtering step comprises the step of filtering movement commands through at least two proportional plus delay filters having staggered zeros bracketing an expected frequency of resonance, to provide a predetermined level of attenuation of the resonance within the frequency uncertainty range.
Claim 4
Dependent Claim
104 words
A filter for processing actuator commands provided to an actuator of a satellite system to reduce resonant mode excitation in the satellite system for a mode of variable or uncertain frequency, said filter comprising: a filter impulse response having a set of equal impulses; said filter having a predetermined level of resonance reduction over at least the frequency uncertainty range of the mode; and wherein said filter comprises a plurality of cascaded posicast filters whose delay values are distinct, yet close enough together so that the frequency response between first zeros of the posicast filters provides at least the predetermined level of resonance reduction.
Claim 5
Dependent Claim
104 words
A filter for processing actuator commands provided to an actuator of a satellite system to reduce resonant mode excitation in the satellite system for a mode of variable or uncertain frequency, said filter comprising: a filter impulse response having a set of equal impulses; said filter having a predetermined level of resonance reduction over at least the frequency uncertainty range of the mode; and wherein said filter comprises a plurality of cascaded posicast filters whose delay values are distinct, yet close enough together so that the frequency response between first zeros of the posicast filters provides at least the predetermined level of resonance reduction.
Claim 6
Dependent Claim
31 words
The filter of claim 3 comprising at least two cascaded posicast filters whose lowest frequency zeros are logarithmically evenly spaced across a frequency range centered on an expected frequency of resonance.
Claim 7
Dependent Claim
12 words
The filter of claims 4 where the actuator is a stepper motor.
Claim 8
Dependent Claim
11 words
The filter of claims 4 where the actuator is a thruster.
Claim 9
Dependent Claim
12 words
The filter of claims 3 where the actuator is a stepper motor.
Claim 10
Dependent Claim
11 words
The filter of claims 3 where the actuator is a thruster.
Claim 11
Dependent Claim
16 words
The filter of claims 3 where the filter impulse response has at least four equal impulses.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-03-10 | 2000-09-09 | 2001-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-03-10 | 2004-09-09 | 2005-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-03-10 | 2008-09-09 | 2009-03-11 | $7700.00 | Window Closed / Lapsed |