US4504032A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control of nutation in a spacecraft
Assignee: Lockheed Martin Corp
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Filing: 1982-03-10
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Granted: 1985-03-12
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Expires: 2002-03-10
Abstract
Abstract A method and apparatus for damping nutation in a spacecraft to essentially zero in less than one nutation period which has a spin axis, first and second transverse axes and a characteristic nutation frequency λ. A time interval t 1 after the transverse momentum of the spacecraft about one transverse axis, such as the Y axis has crossed zero, a torque of magnitude T Y is applied to the spacecraft about its Y transverse axis. After a time interval t 2 , the application of this torque is terminated. The time t 1 =1/λ cos -1 (h Y0 λ/2T Y ) and the time t 2 =2/λ sin -1 (h Y0 λ/2T Y ), where h Y0 is the peak body momentum about the Y transverse axis.
Inventors
- 👤 Kevin J. Phillips
- 👤 Terry G. Tracy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:04
CPC Classifications
B; B64; B64G; B64G1/00; B64G1/22; B64G1/24; B64G1/36; B64G1/28; B64G1/285; B64G1/38
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
141 words
An apparatus for reducing nutation of a momentum stabilized spacecraft to essentially zero in less than a single nutation period where said spacecraft has a spin axis and a characteristic nutation frequency λ, comprising: a torquer for producing a torque of value T j about a first arbitrary axis j transverse to said spin axis; means for sensing the nutational motion of the spacecraft about said first transverse axis; means for energizing said torquer for a time interval t 2 which starts at a time which is a predetermined time period t 1 after the sensed nutational motion crosses zero on said first axis, where: t.sub.1 =1/λ cos.sup.-1 (h.sub.jO λ/2T.sub.j), where h jO =the peak body momentum about the transverse axis j; and means for de-energizing said torquer after said time interval t 2 , where: t.sub.2 =2/λ sin.sup.-1 (h.sub.jO λ/2T.sub.j).
Claim 2
Independent Claim
141 words
An apparatus for reducing nutation of a momentum stabilized spacecraft to essentially zero in less than a single nutation period where said spacecraft has a spin axis and a characteristic nutation frequency λ, comprising: a torquer for producing a torque of value T j about a first arbitrary axis j transverse to said spin axis; means for sensing the nutational motion of the spacecraft about said first transverse axis; means for energizing said torquer for a time interval t 2 which starts at a time which is a predetermined time period t 1 after the sensed nutational motion crosses zero on said first axis, where: t.sub.1 =1/λ cos.sup.-1 (h.sub.jO λ/2T.sub.j), where h jO =the peak body momentum about the transverse axis j; and means for de-energizing said torquer after said time interval t 2 , where: t.sub.2 =2/λ sin.sup.-1 (h.sub.jO λ/2T.sub.j).
Claim 3
Independent Claim
150 words
A method for reducing nutation of a momentum stabilized spacecraft to essentially zero in less than a single nutation period where said spacecraft has a spin axis, a torquer providing a torque value about a first arbitrary axis transverse to said spin axis and a characteristic nutation frequency comprising the steps of: sensing the peak magnitude of nutation motion about said first axis; starting a timer when the sensed nutational motion on said first axis reaches zero; starting said torquer at said torquer value when said timer has timed out t 1 after the nutational motion reaches zero where t 1 is a function of said torque value, said sensed peak magnitude of nutational motion, and said characteristic nutation frequency; and stopping said torquer after time t 2 where t 2 is a function of said torque value, said sensed peak magnitude of nutational motion, and said characteristic nutation frequency.
Claim 4
Independent Claim
150 words
A method for reducing nutation of a momentum stabilized spacecraft to essentially zero in less than a single nutation period where said spacecraft has a spin axis, a torquer providing a torque value about a first arbitrary axis transverse to said spin axis and a characteristic nutation frequency comprising the steps of: sensing the peak magnitude of nutation motion about said first axis; starting a timer when the sensed nutational motion on said first axis reaches zero; starting said torquer at said torquer value when said timer has timed out t 1 after the nutational motion reaches zero where t 1 is a function of said torque value, said sensed peak magnitude of nutational motion, and said characteristic nutation frequency; and stopping said torquer after time t 2 where t 2 is a function of said torque value, said sensed peak magnitude of nutational motion, and said characteristic nutation frequency.
Claim 5
Independent Claim
131 words
A method for reducing nutation in a spacecraft in less than a single nutation period having a spin axis and any arbitrary transverse axis designated axis j, which is orthogonal to the spin axis and said spacecraft having a characteristic nutation frequency λ, comprising the steps of: sensing the peak magnitude of nutation of the spacecraft by sensing the peak momentum h jO of the spacecraft about the transverse axis j; at a time t 1 after the sensed transverse momentum of the spacecraft has reached a zero-crossing, applying a torque of value T j to the spacecraft about said transverse axis j; and terminating the application of said torque to said spacecraft after a time period t 2 , where: t.sub.1 =1/λ cos.sup.-1 (h.sub.jO λ/2T.sub.j) t.sub.2 =2/λ sin.sup.-1 (h.sub.jO λ/2T.sub.j).
Claim 6
Independent Claim
131 words
A method for reducing nutation in a spacecraft in less than a single nutation period having a spin axis and any arbitrary transverse axis designated axis j, which is orthogonal to the spin axis and said spacecraft having a characteristic nutation frequency λ, comprising the steps of: sensing the peak magnitude of nutation of the spacecraft by sensing the peak momentum h jO of the spacecraft about the transverse axis j; at a time t 1 after the sensed transverse momentum of the spacecraft has reached a zero-crossing, applying a torque of value T j to the spacecraft about said transverse axis j; and terminating the application of said torque to said spacecraft after a time period t 2 , where: t.sub.1 =1/λ cos.sup.-1 (h.sub.jO λ/2T.sub.j) t.sub.2 =2/λ sin.sup.-1 (h.sub.jO λ/2T.sub.j).
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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) | 1988-03-11 | 1988-09-10 | 1989-03-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-03-11 | 1992-09-10 | 1993-03-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-03-11 | 1996-09-10 | 1997-03-12 | $7700.00 | Window Closed / Lapsed |