Robust H∞ control of spacecraft rendezvous system with input saturation: A gain scheduled approach

In this paper, the problem of robust H∞ control for spacecraft rendezvous system in the presence of parameter uncertainties, external disturbances and input saturation is addressed. To make full use of the capacity of the limited control, a discrete robust gain scheduled controller based on the parametric Riccati equation approach is designed. The robust gain scheduled controller not only satisfies the input saturation by using the low gain feedback control design method, but also can improve the control efforts by scheduling the control gain parameter increasingly based on a designed parameter set such that the closed-loop system has faster convergence performance and better disturbance attenuation performance than the static gain controllers. Based on the Lyapunov stability theory, it is shown that the closed-loop system under the designed gain scheduled controller has robust H∞ performance. Finally, numerical simulations are performed to demonstrate the effectiveness of the proposed controllers.