Longitudinal automatic control system for a light weight aircraft

This paper presents the design of an automatic control system for longitudinal axis of a light weight aircraft. To achieve this goal it is important to start from the mathematical model in longitudinal plane and then to determine the steady-state parameters for a given velocity and altitude. Using MATLAB Software the mathematical model in longitudinal plane was linearized and the system transfer functions were obtained. To determine the automatic control design we analyzed the stability of the linearized model for each input. After the stability problem was solved, using MATLAB-Simulink Software we designed the control system architecture and we considered that the objective for a stable flight was to continuously adjust the pitch angle θ through control of elevator and velocity through control of the throttle. Finally, we analyzed the performance of the designed longitudinal control system and the results highlighted in graphs outline that the purpose for which it was designed was fulfilled