Attitude control of small satellites using fuzzy logic

Current interest in small satellites lies in the feasibility of achieving specific but limited objectives. By necessity, small spacecraft technology requires simple control schemes, where small attitude errors can be tolerated inside specified deadbands. The attitude control of a small satellite using fuzzy logic is examined in this thesis.; A realistic satellite is modelled as a central rigid body with a set of flexible appendages. The continuous flexible structures are discretized using the assumed modes method. Equations governing the attitude motion and the bending vibrations of the appendages are obtained from the Lagrangian formulation, while the orbital motion is assumed to be Keplerian.; The cases of thrusting and magneto-torquing are considered for the missions of three-axis and spin stabilization of the satellite, respectively. For each case, a set of control rules based on fuzzy logic is formulated to control the polarity and the switching time of the actuators. Control constraints are imposed on the actuators. Various simulations in the presence of environmental disturbances and uncontrolled vibrations of the appendages illustrate the effectiveness of the attitude fuzzy logic controllers.