Almost global attitude stabilization of an orbiting satellite including gravity gradient and control saturation effects

Control saturation effects new results are presented for the problem of attitude stabilization of a rigid satellite in a circular orbit. Most prior results on this problem have addressed use of linear controllers to achieve local asymptotic stability; this paper presents controllers that achieve near global asymptotic stability. This is accomplished by using globally defined models that incorporate gravity gradient effects and a definition of the attitude of the satellite with respect to the rotating local vertical local horizontal coordinate frame. Lyapunov methods are used to analyze the closed loop properties, but their application takes into account the geometry of the tangent bundle TSO(3) on which the global dynamics evolve. Furthermore, the designed control law accommodates control saturation effects