A Hierarchical Fuzzy-Optimal Strategy for Station-Keeping Maneuver of a GEO Satellite

In order to achieve the best possible performance for an artificial satellite, its position and attitude must be maintained within predetermined limits. This is of great importance, especially in the presence of environmental disturbances and system uncertainties. Therefore, performing correction maneuvers is inevitable. This article puts forward a new hierarchal strategy based on fuzzy logic and optimal control theories for correcting the orbital parameters of a geostationary satellite affected by environmental disturbances. The strategy consists of two successive systems referred to as decision-making and optimizing systems. These systems, based on the assessments performed on position and velocity deviations from the nominal reference trajectory, determine the appropriate moments to fire thrusters and their action durations. In this research, the first task, i.e., determining the firing moments of thrusters was accomplished using a fuzzy logic supervisory system. On the other hand, the second task was performed with a direct optimization method based on minimum-fuel station-keeping criterion while considering the constraints of station-keeping problem. The proposed strategy was applied on a geostationary satellite and for a period of 30 days of its motion, and both north-south and east-west orbital corrections were performed. The results obtained from the simulation analysis indicated that the proposed strategy effectively improved the orbital correction procedure of the satellite in the station-keeping mode.