A PPB-SIADP Optimal Fault-Tolerant Attitude Control Scheme for Tailless Flying Wing Aircraft With Actuator Faults and Saturation

This paper addresses the problem of optimal fault-tolerant attitude control with prescribed performance for a tailless flying wing aircraft under actuator faults and saturation. Firstly, by using the time-scale separation principle, the considered state variables of the aircraft are divided into two groups, the angular rate loop and the attitude loop, with different response speeds. Secondly, after prescribed performance bound (PPB) transformation, a novel error tracking nominal system is obtained, based on which an incremental neural network observer is designed to approximate the actuator faults. Thirdly, a functional performance index in terms of the actuator saturation is designed for the nominal system and the corresponding Hamilton-Jacobi-Bellman (HJB) equation is derived. A new single-network incremental adaptive dynamic programming (SIADP) algorithm is proposed to solve the optimal control problem. Moreover, the uniformly ultimately bounded stability of the closed-loop incremental system is proved by using the Lyapunov theory. Finally, simulations are given to illustrate the effectiveness of the proposed control approach.
Note to Practitioners
—The aim of this paper is to develop a new control scheme to realize active fault-tolerant control for tailless flying wing aircraft with actuator faults and saturation. The absence of vertical and horizontal tail fins results in a short longitudinal control moment arm, insufficient longitudinal control efficiency, deep coupling between longitudinal and lateral dynamics and poor stability of the tailless flying wing aircraft. Fault tolerance ability is necessary in flight control design, and the optimal and transient performance with control surface saturation should be considered in control practice. To solve these problems, a PPB-SIADP scheme combined with incremental adaptive observer approach is proposed, the tracking error can converge in an optimal way with prescribed performance. The proposed approach in this paper can be used as a valuable scheme for the tailless flying wing aircraft control law design in engineering practice.