Spacecraft Attitude Control Using Robust Generalized Dynamic Inversion

In this paper, the design of Robust Generalized Dynamic Inversion (RGDI) based attitude control for the rigid body spacecraft is presented. The RGDI control comprises of the particular and the auxiliary parts for tracking of the attitudes and the angular body rates respectively. In the particular part, constraint dynamics based on attitude deviation function is defined in the form of differential equation and is inverted by employing Moore-Penrose Generalized Inverse (MPGI), to realize the control law. The associated null control vector in auxiliary part is constructed which guarantees global closed loop asymptotic stability of spacecraft angular velocities. The singularity issue associated with Generalized Dynamic Inversion (GDI) is handled tactfully by introducing a dynamic scale factor in MPGI. To provide robustness against parametric variations and disturbances, a robust term based on sliding mode control is augmented with GDI control to make it RGDI, such that semi-global practically stable attitude tracking is guaranteed. To analyze the performance of the proposed control method, spacecraft kinematics and dynamics using attitude quaternion are modeled in Simulink/Matlab. Numerical simulations are conducted on the developed spacecraft simulator to demonstrate the tracking performance of the RGDI control.