US3643897A
Expired / Lapsed
US
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Nutation correction system for spin-stabilized satellite
Assignee: International Telecommunications Satellite Organization
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Filing: 1968-10-18
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Granted: 1972-02-22
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Expires: 1988-10-18
Abstract
Abstract A nutation control system for spin-stabilized satellites in which correction thrusters are cyclically fired by timed pulses generated in response to accelerometer signals. Correction is initiated when the accelerometer output exceeds a high-threshold level and continues until it is reduced below a low-threshold level. The termination point is detected by sampling the slope of the accelerometer signal during a window period in each halfcycle.
Inventors
- 👤 George B Johnson Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:55
CPC Classifications
B; B64; B64G; B64G1/00; B64G1/22; B64G1/24; B64G1/26; B64G1/28; B64G1/281; B64G1/38
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
134 words
In a nutation control system for spin-stabilized satellites including an accelerometer producing a sinusoidal output signal proportional to the magnitude of nutational motion, a thruster for developing a force in opposition to the nutational motion, and means for generating cyclical thruster firing pulses in response to the accelerometer signal, the improvement comprising; a. means for initiating the train of thruster-firing pulses when the accelerometer output exceeds a first threshold level, and b. means for terminating the train of thruster-firing pulses when the accelerometer output falls below a second threshold level lower than the first, wherein the terminating means comprises: i. means for sampling the slope of the accelerometer output during a predetermined portion of each cycle, and ii. means for terminating the thruster-firing pulses in response to the slope falling below a predetermined value.
Claim 2
Dependent Claim
134 words
In a nutation control system for spin-stabilized satellites including an accelerometer producing a sinusoidal output signal proportional to the magnitude of nutational motion, a thruster for developing a force in opposition to the nutational motion, and means for generating cyclical thruster firing pulses in response to the accelerometer signal, the improvement comprising; a. means for initiating the train of thruster-firing pulses when the accelerometer output exceeds a first threshold level, and b. means for terminating the train of thruster-firing pulses when the accelerometer output falls below a second threshold level lower than the first, wherein the terminating means comprises: i. means for sampling the slope of the accelerometer output during a predetermined portion of each cycle, and ii. means for terminating the thruster-firing pulses in response to the slope falling below a predetermined value.
Claim 3
Dependent Claim
24 words
A nutation control system as defined in claim 1 further comprising means for ensuring that each thruster firing pulse has a predetermined minimum width.
Claim 4
Dependent Claim
44 words
A nutation control system as defined in claim 1 further comprising means for adjusting the first and second threshold levels and the predetermined value of the slope in response to a ground command signal to compensate for a change in the satellite spin rate.
Claim 5
Dependent Claim
34 words
A nutation control systeM as defined in claim 1 further comprising means for inhibiting the thruster-firing pulses in response to ground command signals to permit the application of attitude correction pulses to the thruster.
Claim 6
Dependent Claim
45 words
A nutation control system as defined in claim 1 wherein there are two diametrically opposed accelerometers, two generating means and two diametrically opposed thrusters, and the outputs of the generating means are crisscrossed to provide a redundant capability in the event of a component failure.
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) | 1975-02-21 | 1975-08-23 | 1976-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-21 | 1979-08-23 | 1980-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-21 | 1983-08-23 | 1984-02-22 | $7700.00 | Window Closed / Lapsed |