For planar motion, of large flexible spacecraft, we consider in the class of relay systems the problem of determining a stable and highly precise control of orientation under conditions Of incomplete information about the spacecraft coordinates and with regard for the fact that the coefficients of the spacecraft model are variable and (or) ill defined. For the class of relay algorithms for stabilization, of the spacecraft angular position, an optimality criterion which minimizes the level of elastic oscillations of the control-excited structure has been introduced. The method of discrete adaptive readjustment of the parameters of the basic algorithm has been proposed. In the environment of a nonstationary spacecraft model, it restrains the value of the varied parameter from leaving the point of global minimum of the function of the optimality criterion. For stabilization of the angular position of a flexible satellite whose model has nonstationary parameters, digital modeling shows that the proposed methods of correction and adaptive adjustment of the parameters of the basic algorithm are operable and that! the system which realizes these principles on the whole stably operates with high precision.
