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Abstract

Roll and yaw attitude control method for a satellite stabilized about its roll, yaw and pitch axes embodying a momentum wheel system generating a continuous angular momentum substantially parallel to the pitch axis and having a variable component at least approximately parallel to the roll-yaw plane and a continuously acting actuator system in which the roll and/or yaw attitude of the satellite is sensed. Control signals are applied to the momentum wheel system that are produced by a fast control loop using a known fast control law and second control signals are applied to the continuously acting actuator system that are produced by a slow control loop using a known slow control law. The continuously acting actuator system is loaded in fixed direction of the satellite parallel to the variable component if the latter has a fixed direction. At least a first additional control signal is applied to the momentum wheel system, chosen to yield a value of the fixed direction component of the angular momentum adapted to compensate in the long term drift of a second fixed direction component of the angular momentum. A second additional control signal is applied to the continuously acting actuator system that is adapted to cancel the effect of the first signal on the attitude with respect to the second fixed direction.

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