IPC분류정보
국가/구분 |
United States(US) Patent
등록
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국제특허분류(IPC7판) |
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출원번호 |
US-0127700
(2002-04-23)
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발명자
/ 주소 |
- Defendini, Ange
- Lagadec, Kristen
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출원인 / 주소 |
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
3 인용 특허 :
3 |
초록
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For controlling the attitude of a satellite placed on a low earth orbit, components of a vector Bm of the earth's magnetic field along three measurement axes of a frame of reference bound with the satellite (typically by means of a three-axis magnetometer) are measured. The orientation of the earth'
For controlling the attitude of a satellite placed on a low earth orbit, components of a vector Bm of the earth's magnetic field along three measurement axes of a frame of reference bound with the satellite (typically by means of a three-axis magnetometer) are measured. The orientation of the earth's magnetic field in the frame of reference is computed and a derivative {dot over (B)}m of the vector is also computed. Magneto-couplers carried by the satellite are energized to create a torque for spinning the satellite at an angular frequency &ohgr;c about a determined spin axis of the satellite, where &ohgr;c is greater than an orbital angular frequency 2&ohgr;0of the satellite.
대표청구항
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1. A method of controlling and stabilizing the attitude of a satellite placed on a low earth orbit, comprising the steps of: measuring components of a vector of the earth's magnetic field along three measurement axes of a frame of reference bound with the satellite, deducting an orientation of
1. A method of controlling and stabilizing the attitude of a satellite placed on a low earth orbit, comprising the steps of: measuring components of a vector of the earth's magnetic field along three measurement axes of a frame of reference bound with the satellite, deducting an orientation of said earth's magnetic field in the frame of reference and a derivative {dot over (B)}m of the vector from said components, and controlling magneto-couplers carried by the satellite based on said orientation and said derivative and exclusive of any additional attitude measurements, so as to create a torque from said orientation and derivative of earth's magnetic field for setting the satellite into rotation at an angular frequency &ohgr; cabout a selected spin axis of the satellite, without need of any internal momentum where &ohgr;cis greater than 2&ohgr;0, &ohgr;0being an orbital angular frequency of the satellite.2. A method according to claim 1, wherein said components are measured using a 3-axes magnetometer.3. A method according to claim 1, further comprising a step of acquisition with exclusive use of measurement of the earth magnetic field, energization of said magneto-couplers and measurement by at least one solar sensor.4. A method according to claim 1, wherein said magneto-couplers are controlled for applying a magnetic torque to the satellite which is Mc=−k({dot over (B)}m-{dot over (B)}i), where: k is a gain, B mis a vector representing the local earth's magnetic field, B ia set vector which represents a bias angular velocity biasing said spin axis to a direction orthogonal to a plane of the orbit.5. A method according to claim 4, wherein the bias angular velocity represented by said vector Biis obtained by causing the magneto-couplers to apply a momentM c=kB.({dot over (b)}m-{dot over (b)}i)=kB.({dot over (b)}m−&OHgr;I×{dot over (b)}m)where B is a standardized scalar representing the earth's magnetic field mean value, {dot over (b)} m, is of the unit vector aligned with {dot over (B)}mwith the same direction {dot over (b)}iis the unit vector aligned with {dot over (B)}iwith the same direction and &OHgr;iis the desired angular velocity vector in a reference frame bound to the satellite.6. A method according to claim 4, wherein the bias angular velocity is generated by a moment which is in a plane orthogonal to the earth's magnetic field {dot over (B)}m.7. A method according to claim 4, comprising the step of adding, in the law determining the magnetic moment Mc, a term generating a torque component biasing the spin axis to a predetermined direction with respect to a direction toward the sun.8. A method according to claim 1, wherein a torque orthogonal to the spin axis is generated with the magneto-couplers for forcing the spin axis away from a direction orthogonal to the plane of the orbit, during or after said setting the satellite into rotation.9. A method according to claim 7, wherein the direction of the spin axis is controlled to be maintained orthogonal to solar generators of the satellite and toward the sun.10. A method of controlling the attitude of a satellite placed into a low earth orbit with an orbital angular frequency of &ohgr; o, said method comprising the steps of: measuring components of a vector of the earth's magnetic field along three measurements axes of a frame of reference with respect to the satellite; determining from said components (i) an orientation of said earth's magnetic field in the frame of reference and (ii) a derivative {dot over (B)} mof the vector, and controlling magneto-couplers carried by the satellite, based on said orientation and said derivative and exclusive of any additional attitude measurements, so as to create a torque setting the satellite into rotation at an angular frequency &ohgr; cabout a selected spin axis of the satellite, without need of any internal momentum, wherein said selected axis can be other than the axis of greatest inertia an d wherein &ohgr;cis greater than 2&ohgr;0.11. A method according to claim 10, wherein said components are measured using a 3-axes magnetometer.12. A method according to claim 10, wherein the method employs an acquisition step solely relying on measurement of the earth's magnetic field, energization of said magneto-couplers and measurement by at least one solar sensor.13. A method according to claim 10, wherein said magneto-couplers are controlled so as to apply a magnetic torque, Mc, to the satellite represented by the equation Mc=−k({dot over (B)}m−{dot over (B)}i) where: k is a gain, B mis a vector representing the local earth's magnetic field, and B iis a set vector representing a bias angular velocity biasing said spin axis into a direction orthogonal to a plane of the orbit of the satellite.14. A method according to claim 13, wherein the bias angular velocity represented by said vector Biis obtained by causing the magneto-couplers to apply a moment according to the equationM c=kB.({dot over (b)}m−{dot over (b)}i)=kB.({dot over (b)}m−&OHgr;i×{dot over (b)}m)where B is a standardized scalar representing the earth's magnetic field mean value, {dot over (b)} mis the unit vector aligned with {dot over (B)}min the same direction, {dot over (b)}iis the unit vector aligned with {dot over (B)}i, in the same direction and &OHgr;i, is the desired angular velocity vector in a reference frame bound to the satellite.15. A method according to claim 13, wherein the bias angular velocity is generated by a moment in a plane orthogonal to the earth's magnetic field {dot over (B)}m.16. A method according to claim 13, further comprising the step of adding, to the equations determining the magnetic moment Mc, a term representing a torque component biasing the spin axis into a predetermined direction with respect to a direction toward the sun.17. A method according to claim 1, wherein a torque orthogonal to the spin axis is generated with the magneto-couplers so as to force the spin axis away from a direction orthogonal to the plane of the orbit, during or after said setting of the satellite into rotation.18. A method according to claim 7, wherein the direction of the spin axis is controlled so as to be maintained (i) orthogonal to solar generators of the satellite and (ii) toward the Sun.
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