Nonparametric Adaptive Attitude Control System Accommodating Nonlinearity and Uncertainty

The purpose of this study is to develop a nonparametric adaptive flight control system that can cope with uncertainty and nonlinearity for the automatic landing system of a spaceplane. The proposed adaptive flight control system is based on a dynamic inversion approach combined with time-scale separation. However, such an approach involves an interaction problem between the inner feedback loop and the outer feedback loop. Also, the nonlinear portions in the dynamics are not sufficiently cancelled by nonlinear state feedback without accurate prior knowledge of the parameters of the controlled system. To solve these problems, a new nonlinear state feedback control combined with observers is presented to estimate unknown signals due to nonlinearity and uncertainty. These techniques allow the control system to neatly avoid the estimation of unknown parameters, unlike in conventional adaptive control. Numerical simulations of the automatic landing of a spaceplane are performed to verify the effectiveness of the proposed method.