Optimal nonlinear estimation for aircraft flight control in wind shear

The continue-time unscented Kalman filter (UKF) is developed to estimate the state of a jet transport aircraft. The UKF is based on the nonlinear longitudinal aircraft equations of motion, and it is designed to provide estimates of horizontal and vertical atmospheric wind inputs. The optimal state and disturbance estimates are incorporated in feedback control laws based on the slow- and fast-time-scale subsystems of the aircraft nonlinear inverse dynamics. The UKF produces accurate estimates, and the resultant flight trajectories are very similar to those obtained with perfect state feedback. The UKF is sensitive to uncertainty in the dynamic model, but much of the lost performance can be restored by treating the uncertainty as a random disturbance input.