SUBOPTIMAL COMMAND GENERATION FOR CONTROL MOMENT GYROSCOPES AND FEEDBACK-CONTROL OF SPACECRAFT
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This paper presents a suboptimal gimbal-angle command generation technique and a Lyapunov-based tracking control law for control moment gyroscopes. The formulation of the open-loop maneuver problem exploits the principle of conservation of angular momentum. This allows for a reduction in the dimensionality of the problem- only the kinematics need be considered. The gimbal rates are parametrized as polynomial functions of time, and the parameters are optimized. The objective function of the optimization is the singularity measure. The optimal null motion used is determined after computing the open-loop gimbal-rate profiles. A feedback strategy is used to track the open-loop reference attitude and angular velocity profiles. Null motion is also used to allow the closedloop gimbal angles to follow the open-loop gimbal-angle histories. This procedure avoids neighboring singularities and also provides repeatability. Simulation results are presented for rest-to-rest maneuvers using a model of a ground-based test article. The results show that a wide domain of singularity-free operation around the reference solution can be provided with this approach. 1995 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.
