Aeronautics and astronautics – Spacecraft – With special crew accommodations
Patent
1984-02-17
1986-05-27
Barefoot, Galen L.
Aeronautics and astronautics
Spacecraft
With special crew accommodations
244164, B64G 136
Patent
active
045911185
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention pertains to the field of stabilizing the attitude of a spacecraft with respect to an astronomical body, e.g., the earth. The spacecraft to be stabilized may be a three-axis stabilized spacecraft or the despun platform of a spin-stabilized space vehicle.
BACKGROUND ART
U.S. Pat. No. 4,114,841 discloses a method for stabilizing an orbiting satellite utilizing magnetic torquing. The magnetic torque can be developed to change the spin rate of the orbiting satellite only when the earth's presence is detected. This superficially appears to be related to that aspect of the present invention in which the signal 14 produced by attitude sensor 3 is clamped to within the astronomical body detection domain 26 in order to limit the spin velocity of spacecraft 2. However, the cited reference pertains to reducing the spin rate of a spin-stabilized satellite about its spin axis. On the other hand, when the present invention is used with a spin stabilized space vehicle, it is to make stationary the despun portion of the space vehicle with respect to an astronomical body such as the earth, and does not relate to the spinning portion of the space vehicle. Furthermore, the cited reference does not use hysteresis as in the present invention.
Similarly, U.S. Pat. No. 3,749,914 pertains to aligning the spin axis of a spin-stabilized space vehicle with respect to an external reference. As stated above, the present invention, in the embodiment in which it is used for a spin-stabilized space vehicle, operates on the despun portion of the space vehicle, not on the spinning portion.
U.S. Pat. Nos. 4,288,051 and 4,358,076 disclose techniques for acquiring the sun and earth from the vantage point of a spacecraft, which techniques could be used by attitude sensor 3 of the present invention.
U.S. Pat. No. 3,834,653 shows a type of torque controller which could be used as torquing means 25 of the present invention. Also note earth time detectors 42 and 44.
U.S. Pat. No. 4,114,842 is a system for recapturing the altitude (not attitude) of an aircraft; it is not a system for stabilizing the attitude of a spacecraft with respect to an astronomical body as in the present invention.
DISCLOSURE OF INVENTION
The present invention is an apparatus for stabilizing the attitude of a spacecraft (2) with respect to an astronomical body (6). On board the spacecraft (2) is an attitude sensor (3) which senses the attitude error angle (A) taken about a sensing axis (4) that is orthogonal to the attitude error angle (A). The error angle (A) is defined as the angle formed between a line (10) fixedly associated with the spacecraft (2) and a line (12) connecting the spacecraft (2) with the centroid of the astronomical body (6). The output attitude signal (14) from the attitude sensor (3) is processed to optimize the spacecraft (2) control loop phase margin, damping, and stability. This is accomplished by:
1. Introducing hysteresis into the attitude signal (14) so that only the velocity informative portion (16) of the signal (14) is presented to the compensation electronics (21), if the most recent history of the error angle (A) indicates that said angle (A) has been outside the detection domain (26) within which the sensor (3) is capable of detecting the presence of the body (3). This eliminates the presentation of that saturated portion (18 or 20) of the attitude signal (14) which has opposite polarity with respect to the velocity of the spacecraft (2) about the sensing axis (4), and therefore avoids unnecessary and unwanted acceleration of the spacecraft (2) about the sensing axis (4).
2. If the most recent history of the error angle (A) indicates that said angle (A) has just left the velocity informative portion (16), hysteresis is provided to inhibit presentation of the attitude signal (14) to the compensation electronics (21) only when the error angle (A) passes out of the detection domain (26). This allows passage of the saturated portion (18 or 20) of the attitude signal (14) having the same polarity with respect t
REFERENCES:
patent: 3636411 (1972-01-01), Bulloch
patent: 3749914 (1973-07-01), Terasaki
patent: 3834653 (1974-09-01), Perkel
patent: 3984071 (1976-10-01), Fleming
patent: 4114841 (1978-09-01), Muhlfelder et al.
patent: 4114842 (1978-09-01), Hofferber et al.
patent: 4174819 (1979-11-01), Bruderle et al.
patent: 4288051 (1981-09-01), Goschel
patent: 4358076 (1982-11-01), Lange et al.
patent: 4386750 (1983-06-01), Hoffman
patent: 4424948 (1984-01-01), Muhlfelder et al.
patent: 4437047 (1984-03-01), Smay
Barefoot Galen L.
Corl Rodney
Ford Aerospace & Communications Corporation
Radlo Edward J.
Zerschling Keith L.
LandOfFree
Hysteresis conditioner for spacecraft attitude control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hysteresis conditioner for spacecraft attitude control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hysteresis conditioner for spacecraft attitude control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1567921