Adaptive Backstepping Control for Spacecraft Hovering with Input Saturation and Parameter Uncertainties

In this paper, an improved adaptive backstepping controller with input saturation is designed to realize the spacecraft approaching and hovering control. The dynamics model for hovering with input saturation is established based on the first-order linearized relative motion model of elliptical reference orbit. An auxiliary system is introduced into the basic backstepping controller to compensate for the effect of input saturation. Then an improved backstepping controller with input saturation is designed and the corresponding stability analysis is also provided via the Lyapunov theory. In order to diminish the influence of parameter uncertainties, the Radial Basis Function Neural Network (RBFNN) is used to estimate the unknown parameters. Numerical simulations are conducted to verify the effectiveness of the proposed method, which can achieve better asymptotic stability than the original method.