Backstepping and nonlinear internal model based attitude tracking and disturbance rejection

In this paper, we consider the attitude tracking and disturbance rejection problem of rigid spacecraft using backstepping and nonlinear internal model method. The Modified Rodrigues Parameters is used as kinematic variables of the rigid spacecraft, which allows principal angle rotations up to 360°. By applying the backstepping design method, we design the Lyapunov function candidate recursively and design the control law directly. The disturbance is handled by a nonlinear internal model, which include the linear internal model as a special case. A numerical example is also given to illustrate the theoretical result presented in this paper.