Robust Tracking of the Flight Path Angle of Aircraft Based on UDE and IID

Nonlinear robust tracking of the flight-path angle in the longitudinal channel of aircraft is a challenging control problem. The main difficulty results from its non-minimum phase characteristics and the unavoidable uncertainty and disturbances existing in the internal dynamics. To solve the problem, this paper presents a nonlinear control scheme based on an Uncertainty and Disturbance Estimator (UDE) and the causal Ideal Internal Dynamics (IID), taking an F-16 aircraft model as the illustrative example. A significant feature of the presented scheme is that it does not need any information about the uncertainties, and that it can be implemented in real time due to the causality of the inversion of the internal dynamics. A numerical simulation example is given to show the effectiveness of the scheme.