Nonlinear predictive attitude control of spacecraft under external disturbances

Abstract

Predictive control technique is applied to the three-axis attitude control of spacecraft under persistent external disturbances. The principal idea of predictive control is to construct a priori reference trajectories of state variables or output vectors and then build con-trol commands so that the actual system follows the reference tra-jectories. The key objective of this paper is how to design a predic-tive controller and estimate the external disturbances simultane-ously for the three-axis attitude control under persistent external disturbances. Conventional predictive controller design approach has been partially modified in conjunction with disturbance identi-fication strategy. The convergence and stability are also discussed for the proposed design technique. In the case of this study, the controlled variables are the spacecraft attitude parameter and body angular velocities. The attitude in-formation is represented with the quaternion parameters and the modified Rodrigues parameters, respectively. The attitude control simulation results are presented to prove this study and compared to the existent control law design method.