Method of determining and controlling the inertial attitude of a spinning, artificial satellite and systems therefor
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
G06F-007/00
B64G-001/36
출원번호
UP-0818723
(2007-06-15)
등록번호
US-7739003
(2010-07-05)
발명자
/ 주소
Johnson, William M.
출원인 / 주소
Johnson, Kara Whitney
Johnson, Brett Harper
대리인 / 주소
Weingarten, Schurgin, Gagnebin & Lebovici LLP
인용정보
피인용 횟수 :
5인용 특허 :
0
초록▼
A method of and apparatus for determining and controlling the inertial attitude of a spinning artificial satellite without using a suite of inertial gyroscopes. The method and apparatus operate by tracking three astronomical objects near the Earth's ecliptic pole and the satellite's and/or star trac
A method of and apparatus for determining and controlling the inertial attitude of a spinning artificial satellite without using a suite of inertial gyroscopes. The method and apparatus operate by tracking three astronomical objects near the Earth's ecliptic pole and the satellite's and/or star tracker's spin axis and processing the track information. The method and apparatus include steps and means for selecting preferably three astronomical objects using a histogram method and determining a square of a first radius (R12) of a track of a first astronomical object; determining a square of a second radius (R22) of a track of a second astronomical object; determining a square of a third radius (R32) of a track of a third astronomical object; determining the inertial attitude of the spin axis using the squares of the first, second, and third radii (R12, R22, and R32) to calculate pitch, yaw, and roll rate; determining a change in the pitch and yaw of the artificial satellite; and controlling on-board generated current flow to various orthogonally-disposed current-carrying loops to act against the Earth's magnetic field and to apply gyroscopic precession to the spinning satellite to correct and maintain its optimum inertial attitude.
대표청구항▼
What is claimed is: 1. A method of determining and controlling an inertial attitude of an artificial satellite about a spin axis, the method comprising: determining a square of a first radius (R12) of a track of a first astronomical object; determining a square of a second radius (R22) of a track o
What is claimed is: 1. A method of determining and controlling an inertial attitude of an artificial satellite about a spin axis, the method comprising: determining a square of a first radius (R12) of a track of a first astronomical object; determining a square of a second radius (R22) of a track of a second astronomical object; determining a square of a third radius (R32) of a track of a third astronomical object; determining the inertial attitude of the spin axis using the squares of the first, second, and third radii (R12, R22, and R32) to calculate pitch, yaw, and roll; determining a change in the pitch and yaw of the artificial satellite necessary to maintain said inertial attitude; and applying gyroscopic precession to maintain said inertial attitude. 2. The method as recited in claim 1, wherein determining the change in the pitch and yaw includes: determining an optimum pitch and yaw; measuring an instantaneous pitch and yaw; comparing the optimum pitch to the current pitch to determine a pitch error; comparing the optimum yaw to the current yaw to determine a yaw error; and controlling at least one of the torque-producing devices to gyroscopically precess the artificial satellite. 3. The method as recited in claim 2, wherein the steps for determining the change in the pitch and yaw are repeated until at least one of the pitch error and the yaw error is nulled. 4. The method as recited in claim 3, wherein nulling the pitch error and the yaw error includes: estimating the Earth's magnetic field using a virtual model of the Earth's magnetic field in conjunction with the inertial attitude of the artificial satellite; providing at least one torque-producing device on a plurality of outer surfaces of the artificial satellite; and controlling at least one of an amount and a direction of current flowing through at least one of the at least one torque-producing devices to correct the change in pitch and yaw. 5. The method as recited in claim 3, wherein nulling the pitch error and the yaw error includes: providing at least one torque-producing device on a plurality of outer surfaces of the artificial satellite; providing a pre-determined amount of current flowing through at least one of the at least one torque-producing devices; measuring a precession rate of the artificial satellite; estimating the Earth's magnetic field using the precession rate and pre-determined current; and controlling at least one of an amount and a direction of current flowing through at least one of the torque-producing devices to correct the change in pitch and yaw. 6. The method as recited in claim 3, wherein nulling the pitch error and the yaw error includes: measuring the Earth's magnetic field; providing at least one torque-producing device on a plurality of outer surfaces of the artificial satellite; and controlling at least one of an amount and a direction of current flowing through at least one of the at least one torque-producing devices to correct the change in pitch and yaw. 7. The method as recited in claim 6, wherein providing at least one torque-producing device on the artificial satellite includes: disposing each of a plurality of current-carrying loops on a plurality of outer surfaces of the artificial satellite orthogonal or substantially orthogonal to every other current-carrying loop of said plurality of current-carrying loops; providing a partitioned power generating device; and electrically coupling each part of the partitioned power generating device to each of the plurality of current-carrying loops. 8. The method as recited in claim 7, wherein providing a plurality of orthogonal, current-carrying loops includes disposing a first current-carrying loop on a top side of the artificial satellite, a second current-carrying loop on a bottom side of the artificial satellite, and four current-carrying loops around a circumferential surface of the artificial satellite. 9. The method as recited in claim 6, wherein measuring the Earth's magnetic field includes sensing the polarity of said magnetic field. 10. An article of manufacture having computer-readable program means for executing the method of claim 2. 11. The article of manufacture of claim 10 having a capability to uplink and to downlink commands with a terrestrial-based control processor. 12. The method as recited in claim 1, wherein determining the change in pitch and yaw includes: measuring an instantaneous pitch error and in instantaneous yaw error; comparing the instantaneous change in pitch error and the instantaneous change in yaw error with zero; and controlling at least one of an amount and a direction of current flowing through at least one of the at least one torque-producing devices to correct the change in pitch and yaw, wherein the above-steps are repeated until at least one of the change in pitch error and the change in yaw error is nulled. 13. The method as recited in claim 12, wherein controlling said amount and/or said direction of current includes interacting the current with the Earth's magnetic field to produce a torque. 14. The method as recited in claim 1 further comprising controlling the inertial attitude of the artificial satellite using a closed-form solution. 15. The method as recited in claim 14, wherein controlling the inertial attitude of the artificial satellite using a closed-form solution includes: disposing a star tracking device at or near the spin axis of the artificial satellite; structuring and arranging the star tracking device to have a small field-of-view and a line-of-sight at the spin axis of the artificial satellite; and determining the square of a first radius (R12) of the track of the first astronomical object, determining the square of a second radius (R22) of the track of the second astronomical object, determining the square of a third radius (R32) of the track of the third astronomical object using data produced by the star tracking device. 16. The method as recited in claim 15, wherein controlling the inertial attitude of the artificial satellite using a closed-form solution includes using a star tracking device includes: deploying the artificial satellite such that a spin vector associated with and normal to the spin axis is aligned within a narrow region of the ecliptic plane of the Earth; selecting the first astronomical object, the second astronomical object, and the third astronomical object from among a plurality of astronomical objects that are within a few degrees of an ecliptic pole normal to the Earth's ecliptic plane; and establishing the inertial attitude of the artificial satellite with respect to the first astronomical object, the second astronomical object, and the third astronomical object. 17. The method as recited in claim 16, wherein the first astronomical object, the second astronomical object, and the third astronomical object are selected from among a plurality of known astronomical objects that are within about 0 to about 10 degrees of an ecliptic pole normal to the Earth's ecliptic plane. 18. The method as recited in claim 17, wherein the first astronomical object, the second astronomical object, and the third astronomical object are selected from among a plurality of known astronomical objects that are within about five degrees of an ecliptic pole normal to the Earth's ecliptic plane. 19. The method as recited in claim 15 further comprising: identifying the first astronomical object, the second astronomical object, and the third astronomical object by measuring a relative intensity of each of the first astronomical object, the second astronomical object, and the third astronomical object; and comparing the relative intensities of each of the first astronomical object, the second astronomical object, and the third astronomical object with known relative intensities of the plurality of astronomical objects that are within a few degrees of the ecliptic pole. 20. The method as recited in claim 1, wherein determining the inertial attitude of the spin axis includes calculating a right ascension (RA) and declination (DEC) of said spin axis. 21. The method as recited in claim 20, wherein maintaining the inertial attitude includes controlling at least one of an amount and a direction of current flowing through at least one of the at least one torque-producing devices to maintain the spin axis at the calculated RA and DEC. 22. The method as recited in claim 1, wherein determining the change in the pitch and yaw of the artificial satellite includes, calculating a right ascension and declination based on the squares of the first, second, and third radii (R12, R22, and R32); comparing the calculated right ascension and declination with an optimum right ascension and declination; and determining an right ascension error and a declination error. 23. An article of manufacture having computer-readable program means for executing the method of claim 1. 24. The article of manufacture of claim 23 having a capability to uplink and to downlink commands with a terrestrial-based control processor. 25. The method as recited in claim 1, further comprising: applying gyroscopic precession to adjust the spin rate of the artificial satellite. 26. A method of predicting an inertial attitude of an artificial satellite about a spin axis after a period of no control or no data, the method comprising: determining a square of a first radius (R12) of a track of a first astronomical object; determining a square of a second radius (R22) of a track of a second astronomical object; determining a square of a third radius (R32) of a track of a third astronomical object; determining the inertial attitude of the spin axis using the squares of the first, second, and third radii (R12, R22, and R32) to calculate pitch, yaw, and roll; and predicting a change in the pitch and yaw of the artificial satellite to estimate when to apply gyroscopic precession to maintain said inertial attitude. 27. A method for determining an inertial attitude about a spin axis of a artificial satellite, comprising: determining a square of a first radius (R12) of a first track of a first astronomical object; determining a square of a second radius (R22) of a second track of a second astronomical object; and determining a square of a third radius (R32) of a third track of a third astronomical object; determining the inertial attitude based on the first, second and third radius squared (R12, R22 and R32), without calculating a first, second or third radius (R1, R2 or R3) from the first, second or third radius squared.
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이 특허를 인용한 특허 (5)
Cosner, Christopher M.; Nakasone, Dennis Y., Agile dedicated spacecraft for spinning microwave imagers and sounders.
Johnson, William M., Method and computer program product for controlling inertial attitude of an artificial satellite by applying gyroscopic precession to maintain the spin axis perpendicular to sun lines.
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