| The integration and the development of the flight control system for the modern aircraft presents a high order system. The norm MIL-STD-1797A, developed the LOES technique in order to evaluate the handling qualities in frequency domain. Other methods of reduction are used to evaluate the handling qualities in time domain.; In this project, we present three methods of reduction and their applications to an aircraft model provided by Bombardier Aeronautics: The first method is the aircraft dynamics reduction, based on the elimination of some state variables of the aircraft dynamics, the second method, provided by Bombardier Aeronautics, is based on the elimination of two state variables of the closed loop system and the third method is the low-order equivalent system (LOES). The algorithm used to obtain the LOES is the least square fit of frequency response of the original high order system.; In order to compare these methods, we use the same gains for the controller, obtained by the optimization function (CONSTR) for certain flight cases.; The most important recommendation is to choose the appropriate reduced method that keeps the important information of the aircraft dynamics, before making the design of the flight control system. |
