Aeronautics and astronautics – Spacecraft – Attitude control
Patent
1996-01-16
1998-02-10
Kashnikow, Andres
Aeronautics and astronautics
Spacecraft
Attitude control
244158R, B64G 123
Patent
active
057160317
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention concerns an artificial satellite equipped with aerodynamic rudders to control the orientation of the satellite.
It applies more specifically to artificial satellites whose orbit is low, that is, whose perigee is several hundred kilometers from the surface of the ground, at an altitude where the air is rarefied, but where its influence cannot be neglected.
The traditional means of orienting satellites consist of wheels that use gyroscopic or jet effects and turn at a speed controlled by generators of magnetic forces and by fuel thrusters, but all these devices have the disadvantage of being heavy, consuming relatively large quantities of energy when they operate and not being extremely precise, since vibrations or shocks are transmitted to the satellite.
The invention proposes replacing or supplementing these devices with rudders, that is, variable-orientation louvers which are subject to air resistance to orient the satellite: their orientation is controlled at will to obtain an aerodynamic force that makes it possible to control the satellite; they can also be placed in a resting position, where they have little influence, if not potentially a beneficial protective effect.
The invention is characterized, in the most general form, by the fact that the satellite has pitch rudders at the front and rear of a main body encompassing the center of gravity of the satellite; these pitch rudders are mobile, rotate around transverse axes, and are symmetrical to a median longitudinal plane that goes through the center of gravity of the satellite. The pitch rudders can be made so as to avoid creating dead zones behind them, which would make control of the rudders inoperative at small angles of deviation from the resting position; for this, they can include front louvers on the free ends, away from the main body, or can be formed of panels that get thicker toward the transverse axes of rotation. The satellite can also be equipped with mobile roll and yaw rudders on the left and right that rotate on transverse axes. It can then be oriented according to all its axes, especially if the rudders are composed of pairs symmetrically in relation to the median longitudinal plane of the satellite and especially if there are two of these pairs, since then the yaw and the roll can be controlled independently.
A third aspect of the invention, which can be used in combination with the preceding ones, concerns certain turning objects such as sighting mirrors, or the rudders themselves if necessary, because their control is accompanied by forces of inertia which destabilize the satellite. The invention provides that each system comprising one of these objects, the motor that propels it and the transmission that connects the object to the motor has a total kinetic moment of zero when the motor is propelling the object. This design can, of course, be applied to the rudders themselves.
Now we will move on to a concrete description of the invention using the following attached figures as illustrative, but not limiting:
FIG. 1 shows the satellite schematically in perspective under cover of the launcher,
FIG. 2 shows a bottom view of the satellite deployed in orbit,
FIG. 3 shows how the first system of pitch rudders is activated,
FIG. 4 shows a system of rudders on the satellite,
FIG. 5 shows another system of rudders,
FIG. 6 shows a detail from FIG. 5,
FIGS. 7A and 7B show curves for pitch force as a function of the angular deviation of the rudders,
FIG. 8 shows a system for transmitting zero total kinetic force,
FIG. 9 shows reference marks for the axes, And FIGS. 10A and 10B show a last system of rudders for the satellite.
The figures show various views of the satellite and various aspects of the invention. A satellite (FIGS. 1 and 2) has a center of gravity 0 and longitudinal Xs, transverse Ys and vertical Zs geometric axes intersecting at that point according to FIG. 2 and linked to the satellite; the axes have been shown apart from the satellite on other figures for reasons of clarity. The satellite is compo
REFERENCES:
patent: 3184187 (1965-05-01), Isaac
patent: 3304028 (1967-02-01), Dryden
patent: 4426052 (1984-01-01), Hubert et al.
patent: 5350138 (1994-09-01), Culbertson et al.
patent: 5487791 (1996-01-01), Everman et al.
Centre National d'Etudes Spatiales
Dinh Tian
Kashnikow Andres
LandOfFree
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