An attitude controller for under-actuated spacecraft with two flywheels
基于飞轮的欠驱动航天器姿态控制器设计

The spacecraft with flywheels becomes under-actuated and the attitude controllability goes worse when only two flywheels can work.We deal with this problem for a rigid spacecraft with two flywheels.A new controller is designed by using the Backstepping design method,under the assumption of zero momentum for the spacecraft.The design process is in two steps:First,the desired angular velocity is designed to stabilize the attitude of the spacecraft,by considering the kinematics only.Next,the dynamics is combined to give the attitude control torque.The controller is a discontinuous one. It makes the attitude of the under-actuated spacecraft globally asymptotically converge to zero,and the system has a rapid and desirable transient process.Finally,simulation results indicate the feasibility of the controller presented above.