Unstable Aircraft Flight Control Based on LMI with Consideration of Control and Saturation Constraints

In this paper, limitation in actuator capacity has been used as a key role in the design of the flight control system. In order to guarantee the performance and stability of flight control systems in the presence of saturation, in flying high angle of attack area, the development of linear matrix inequality, optimization techniques, and numerical methods are proposed, and the integration of these methods with saturated controllers is introduced. Also, in this paper, the combination of two anti-windup method and direct saturation method in the tracking problem of flight path angle is discussed. For this purpose, the nonlinear model of the aircraft is modeled, moreover the linear model is obtained at the trim operation condition. Then the controller is designed to track maneuver flight path angle regardless of saturation. In the following, considering the maximum disturbance involved in aircraft maneuvering, a safe controller that guarantees performance and stability is designed, and gain scheduling technique to prevent conservatism in the use of controllers is employed. The results of the nonlinear and linear model of the aircraft are presented in tracking the flight path angle at high angle of attack with consideration of control and saturation constraints in unstable operation condition. Simulation results, indicating the improvement of the mentioned control method for an unstable aircraft.