Method of and apparatus for returning an earth orbiting spacecraft to an earth pointing attitude after displacement therefrom
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
B64G-001/24
F41G-007/00
출원번호
US-0331322
(1989-03-31)
우선권정보
GB-19880009247 (1988-04-20)
발명자
/ 주소
Matthews, Nicholas
출원인 / 주소
British Aerospace Public Limited Company
대리인 / 주소
Cushman, Darby & Cushman
인용정보
피인용 횟수 :
7인용 특허 :
1
초록▼
An Earth orbiting spacecraft (1) is returned to an Earth pointing attitude by means of a star sensor (6), Earth sensor (2), Sun sensor (4) and an angular momentum storage device. With the Sun sensor (4) locked on the Sun (5) the spacecraft is rotated until the star sensor (6) senses a predetermined
An Earth orbiting spacecraft (1) is returned to an Earth pointing attitude by means of a star sensor (6), Earth sensor (2), Sun sensor (4) and an angular momentum storage device. With the Sun sensor (4) locked on the Sun (5) the spacecraft is rotated until the star sensor (6) senses a predetermined brighter than magnitude 3 star such as Canopus (7). The angular momentum storage device is operated to preserve an attitude reference and the spacecraft (1) is further rotated by an angle α such that subsequent rotation around the angular momentum storage axis causes the Earth (3) to enter the view of the Earth sensor (2).
대표청구항▼
1. A method of returning an Earth orbiting spacecraft to an Earth pointing attitude after displacement therefrom, utilizing apparatus on the spacecraft which includes an Earth sensor which has a boresight, at least one Sun sensor having a boresight offset from the Earth sensor boresight, a star sens
1. A method of returning an Earth orbiting spacecraft to an Earth pointing attitude after displacement therefrom, utilizing apparatus on the spacecraft which includes an Earth sensor which has a boresight, at least one Sun sensor having a boresight offset from the Earth sensor boresight, a star sensor having a boresight substantially at right angles to the Sun sensor boresight for sensing the position of a predetermined reference star, actuator means operable in response to the sensors to change the spacecraft attitude and an angular momentum storage device which has an angular momentum storage axis in a direction having an angle in the range of 30 to 150 degrees to the Sun sensor boresight and aligned with a principle axis of the spacecraft, which method includes the steps of maintaining the spacecraft in an attitude in which the Sun is on the Sun sensor boresight, rotating the spacecraft around a Sun sensor-Sun line until the predetermined reference star enters the view of the star sensor, operating the angular momentum storage device to accumulate angular momentum sufficient to preserve an attitude reference, further rotating the spacecraft around the Sun sensor-Sun line by an angle α computed from astronomical tables in dependence upon the time of day and time of year, such that a subsequent rotation of the spacecraft around the angular momentum storage axis causes the Earth to enter the view of the Earth sensor, releasing the spacecraft from alignment of the Sun sensor boresight on the Sun, and rotating the spacecraft about the angular momentum storage axis until the Earth enters the view of the Earth sensor. 2. A method according to claim 1, in which the predetermined reference star sought by the star sensor is Canopus. 3. A method according to claim 1 or 2, in which after the spacecraft is rotated around the Sun sensor-Sun line by the angle α any residual motion due to a total angular momentum vector not being aligned with the angular momentum storage axis is damped in a manner without any net external angular impulse. 4. A method according to claim 3, in which if, after the Earth has entered the view of the Earth sensor, it is necessary to correct the attitude around the spacecraft-Earth direction to nominal, the angular momentum vector is precessed by an angle β around the Earth sensor-Earth line to the nominal orientation, which angle β is computed in dependence upon the time of day and the time of year. 5. Apparatus for returning an Earth orbiting spacecraft to an Earth pointing attitude after displacement therefrom, which apparatus includes an Earth sensor having a boresight for sensing the position of the Earth relative to the spacecraft and capable of producing an output signal indicative of the Earth position, at least one Sun sensor, having a boresight offset from the Earth sensor boresight, for sensing the position of the Sun relative to the spacecraft and capable of producing an output signal indicative of the Sun position, a star sensor, having a boresight substantially at right angles to the boresight of the Sun sensor, for sensing a position of a predetermined reference star and capable of producing an output signal indicative of the position of the reference star, actuator means for changing the spacecraft attitude, an angular momentum storage device which has an angular momentum storage axis in a direction having an angle in the range of 30 to 150 degrees to the Sun sensor boresight and aligned with a principle axis of the spacecraft, and control means for processing the output signals of the Earth sensor, Sun sensor and star sensor and operating the actuator means to change the spacecraft attitude accordingly. 6. Apparatus according to claim 5, wherein the Earth sensor is operable to measure the direction of the Earth about two orthogonal axes. 7. Apparatus according to claim 6, wherein the Sun sensor is operable to measure the direction of the Sun about two orthogonal axes. 8. Apparatus according to claim 7, wherein the Sun sensor boresight is offset from the Earth sensor boresight by an angle in the range of 30° to 150°. 9. Apparatus according to claim 8, wherein the Sun sensor boresight is offset from the Earth sensor boresight by substantially 90°. 10. Apparatus according to claim 9, wherein the star sensor is operable to sense the position of a predetermined reference star which is brighter than magnitude 3. 11. Apparatus according to claim 10, wherein the predetermined reference star whose position is sensed by the star sensor is Canopus. 12. Apparatus according to claim 11, wherein the angular momentum storage device is capable of storing angular momentum in a direction substantially at right angles to the Sun sensor boresight, and in operation of the apparatus, is aligned with a principal axis of the spacecraft. 13. Apparatus according to claim 12, wherein the control means includes means for processing the output signal of the Earth sensor and operating the actuator means to maintain the Earth on the Earth sensor boresight. 14. Apparatus according to claim 13, wherein the control means includes means for processing the Sun sensor output and operating the actuator means to maintain the Sun on the Sun sensor boresight. 15. A spacecraft having an apparatus according to claim 5.
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이 특허에 인용된 특허 (1)
Muhlfelder ; Ludwig ; Keigler ; John Edward ; Stewart ; Brian, Momentum biased active three-axis satellite attitude control system.
Brumfield, Bruce; Price, Xenophon H.; White, George E.; Hirschberg, Philip C.; Chan, Kam, Spacecraft three-axis attitude acquisition from sun direction measurement.
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