Generalized predictive control of spacecraft attitude with adaptive predictive period

In this article, a dynamic nonlinear generalized predictive control method based on exponential function to adjust predictive period is proposed for the problem of spacecraft attitude tracking with model uncertainties and unknown disturbances. First, a virtual generalized predictive control law is designed on the basis of invariable predictive period for attitude subsystem. Subsequently, introducing predictive period into attitude, a closed-loop error equation for fusion of attitude and predictive period is established. Meanwhile, a dynamic adaptive law of predictive period and a disturbance estimator are built in the light of Lyapunov theory. Second, through a similar approach, an actual control input is designed for the attitude angular velocity subsystem. In order to simplify the calculation, the derivatives of virtual control and unknown disturbances in the actual control are dealt with adaptive estimators by considering them as uncertainties. Finally, it is proved that the spacecraft attitude can converge to the desired attitude of bounded small neighborhood. The simulation results of comparative analysis demonstrate that the predictive period can be adjusted to improve the control performance and speed up the attitude convergence.