Research on lateral-directional stability augmentation system of flying wing aircraft based on reliability model

Abstract

Poor lateral-directional stability is a great risk to the design of flying wing aircraft due to the absence of vertical stabilizer. In order to improve the lateral-directional flying quality of this configuration aircraft, eigenstructure assignment technique by state feedback is adopted to design the stability augmentation system. The influence of eigenstructure on energy consumption of the control system is analyzed by citing energy consumption index in this paper. In addition, a reliability model is established to measure the reliability of the control system under uncertain factors. In order to assign eigenvalues and eigenvectors to obtain the control law of the system, a nested optimization model based on coupling degree, energy consumption and reliability is proposed. The outer optimization is used to optimize the eigenstructure, and inner optimization is used to compute the reliability of the control system in optimization process. A flying wing aircraft is used as a basis for the design of the stability augmentation system through the suggested optimization strategy. The optimization results demonstrate the validity of the method, and the lateral-directional flying quality of the aircraft has been improved greatly.