Aeronautics and astronautics – Spacecraft – With special crew accommodations
Patent
1994-07-27
1996-09-24
Barefoot, Galen L.
Aeronautics and astronautics
Spacecraft
With special crew accommodations
B64G 136
Patent
active
055583059
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to a measuring arrangement for determining the sun and earth orientation of a three-axis stabilized satellite and a corresponding process for determining the rotational velocity of the satellite and the deviation of the satellite as well as to a system for implementing attitude control maneuvers by using such a measuring arrangement and corresponding regulating processes.
A measuring arrangement of the initially mentioned type is known from H. Bittner, et al., "The Attitude Determination and Control Subsystem of the Intelsat V Spacecraft", Proceedings of AOCS Conference, Nordwijk, Oct. 3 to 6, 1977, ESA SP-128, November 1977. The satellites of this known type have a redundantly designed speed gyroscope package which measures in all three axes X, Y, Z of the satellite-fixed system of coordinates, as well as several sun sensors which are also designed in a redundant manner and have two fields of view. One field of view is centered about the negative Z-axis, which comprises one half of the XZ-plane, and has a specific width perpendicularly with respect to it (in the direction of the Y-axis). The other filled of view is centered about the positive X-axis, comprises one third of the XY-plane and also has a specific width perpendicularly to it. This sensor arrangement is used for tracking, in a measuring manner, rotations of the satellite body, that is, the components of the rotational speed vector of the satellite and, irrespectively of it, detecting the orientation of the satellite with respect to the sun by the determination of the sun vector pointing from the satellite to the center of the sun as soon as the sun is in the field of view of the sun sensors. The measuring results supplied by the sensors are used by the attitude control system of the satellite for commanding attitude changes or rotations in a targeted manner in order to be able to carry out the maneuvers required in the transfer orbit and in the final satellite orbit and to be able to correct occurring attitude deviations.
The speed gyroscopes used for the measuring, control and damping of rotational movements of the satellite are very complicated electromechanical precision devices, and are therefore correspondingly expensive and susceptible to disturbances. For meeting the reliability requirements under the extreme environmental conditions in space, particularly in the case of long-time missions, these devices must also be present in a redundant manner, which also increases the expenditures with respect to cost and weight. When one measuring axis is absent in a gyroscope package containing several speed gyroscopes, the remaining gyroscope axes can generally also no longer be used. Since the possibility of failure of a system rises with the number of functional elements, the use of a measuring system with a large number of electromechanical components which are susceptible to disturbances also has a higher risk of failure.
The invention is therefore based on the object of providing a measuring arrangement of the above-mentioned type which is less expensive and more reliable. By means of this measuring arrangement, it must be possible to carry out largely automatically on board of the satellite all maneuvers required in the transfer orbit as well as in the final satellite orbit, particularly in the geosynchronous orbit. Furthermore, if possible, the number of components which are susceptible to disturbances is to be reduced to a minimum.
The required maneuvers include: sun acquisition from any starting position; the earth acquisition from the sun orientation; alignment for the apogee maneuver, attitude stabilization in the desired orientation and the damping of movement during the maneuver period in the transfer orbit; as well as the earth and sun reacquisition in the geosynchronous orbit.
This object is achieved by the according to the invention, which measuring comprises a plurality of sun sensors arranged such that the measuring of the components of the sun vector is made possible
REFERENCES:
patent: 5042752 (1991-08-01), Surauer et al.
patent: 5062592 (1991-11-01), Kishimoto
patent: 5080307 (1992-01-01), Smay et al.
patent: 5130931 (1992-07-01), Paluszek et al.
patent: 5255879 (1993-10-01), Yocum et al.
Bittner Helmut
Fichter Walter
Fischer Horst-Dieter
Surauer Michael
Barefoot Galen L.
Deutsche Aerospace AG
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