Implementation of a Spacecraft Solar-Orientation Model Using a Reaction-Wheel System

The mode of maintaining a solar orientation of spacecraft–gyrostat in low Earth orbit for a long time has been studied. The spacecraft is close to a cylinder in shape with two fixed solar arrays. The arrays are located along the longitudinal axis of the cylinder, symmetrically with respect to it. In the solar-orientation mode, the normal to the plane of the spacecraft solar arrays is invariably directed to the Sun, and the longitudinal axis oscillates relative to the plane of the orbit. To implement the specified mode of the spacecraft motion, a system of four reaction wheels is used, the rotation axes of which are directed parallel to the lateral edges of the quadrangular pyramid. The position of the lateral edges of the pyramid relative to the coordinate system rigidly connected to the spacecraft is given by two angles, which are the parameters of the reaction-wheel system. The law of control of the gyrostatic moment is considered, which ensures the attenuation of the perturbed motion of the spacecraft in the vicinity of the position of its solar orientation and limits the accumulation of the own kinetic moment of the reaction wheels by controlling the angle of rotation of the spacecraft around the normal to the light-sensitive side of the solar arrays. The study shows that with the help of a certain choice of parameters of the reaction-wheel system, it is possible to implement the solar-orientation mode without unloading the gyrostatic moment during the entire flight time. The results of numerical simulation of the complete system of equations of the spacecraft motion in the mode of its solar orientation, taking into account the influence of gravitational and aerodynamic moments, are presented, confirming the correctness of the chosen values of the parameters.