Abstract: Since space station is a nonlinear system in essence, it is difficult to realize the high-performance attitude control and momentum management using ordinary linear control strategies. In this paper, a nonlinear attitude/momentum controller is designed according to the nonlinear dynamics of space station. However, the periodic fluctuations still exist in the attitude and attitude rate due to the cyclic disturbances, such as the aerodynamic torque. Therefore, an improved nonlinear controller is presented for the extended attitude control/momentum management system after a cyclic-disturbance rejection filter is introduced. Using this controller, the attitude fluctuations can be restrained to great extent. Furthermore, this controller can establish a proper tradeoff between station pointing and momentum management of control moment gyroscopes, while satisfying the specific mission requirements. Controller parameters are easy to regulate since they have definite physical meanings. Simulation results of a certain space station indicate that the controller presented above is feasible.

Key words: spacecraft control, attitude control, nonlinear control, space station, control moment gyroscopes