Aircraft Control System Modeling And Simulation Studies

A complete mathematics model of a flight control system which includes hybrid mechanism system is established after analyzing the three channel (the Aileron, the Elevator and the Rudder) mechanical structure of it. The flexible drive of the hybrid mechanism system is treated as a hard one; the distributed system parameters are centralized, and modeled by means of equivalent dynamic modeling.The characteristic of front section mechanical system (from the pilot staff to the input of the hydraulic servo actuating system) of the flight control system is analyzed by means of Resonance and Zhao-Lin Split Factor method, found out whether the second and the third sequence frequency will be coupled with the vibration mode of the flight-flight control system. The back section mechanical system (from the input of the reversible hydraulic servo actuating system to the rudder) is linearized, and the order is reduced to the fourth-order and the first-order.By using Matlab/Simulink, the simulation results show that the model is identical to the real one in both static and dynamic performance. By using GLSE-Generalized Least Squares Estimation to the input and output datum of the system, a equivalent system comprise second order model and delay term of the actual nonlinear system is identified in different flight condition. In order to improve the calculate precision the QR-Householder Transform is adopted in solve the equation.The frequency characteristic of the vehicle control system is analyzed, and the Bode figures are given. The influence and the trend of the system parameters change to the system performances are analyzed and summarized.The model can be used in the PIO analysis directly, and by means of reducing the order of it can be used in the analysis of dynamic characteristic, coupling between control system and flight control system.