Robust adaptive attitude control for flexible spacecraft in the presence of SGCMG friction nonlinearity

This paper investigates attitude maneuver control issues of a flexible spacecraft with pyramid-type single gimbaled control moment gyroscopes (SGCMGs) as the actuator. The LuGre friction model is adopted to precisely describe the nonlinearity of the SGCMG gimbal friction. Aiming at restraining the adverse effects of the friction existed in SGCMG on the attitude control performance, a robust adaptive attitude controller is proposed, and projection-based adaptive laws are presented to estimate the friction parametric uncertainties and the bound of friction nonlinearity. By treating the flexible mode coupling effect and external disturbances as lump disturbances, the inertia uncertainties and the bound of the lump disturbances are also estimated and compensated simultaneously to reduce their adverse effect on the system. With the Lyapunov technique, the states of flexible spacecraft control system are proved to be uniformly ultimately bounded. Numerical simulations demonstrate the effectiveness of the proposed scheme.