Research On Flight Control Technology Of Cruise Section Of Passenger Aircraft

Generally speaking,the time is the maximum when a plane is under the cruising state during the course of flying.A plane under the cruising state uses an automatic flight control system,which can greatly reduce the operating burden of a pilot.It can not only reach the goal of saving fuel and being secure by tracing the route,but also give passengers a comfortable experience for flying.In this thesis,the automatic flight control systems are designed by using classical control methods and digital imitation is done using an entire motion model as flight dynamic model.The automatic style for flying which is described in this thesis is set by analyzing the present situation of control law of larger planes at home and abroad and by referring to excellent articles at home and abroad.Finally,the state-space representation of A300 under the cruising state is obtained by using the way modeling by mechanism to make nonlinear flight dynamic model and using the way of linearization of small perturbation to specifically analyze larger planes.The motion characteristics of planes are given time-domain analysis on which the following design and simulation of automatic flight control law.Aiming at the performance of instruction tracking,the control laws of lateral channel and longitudinal channel are designed by using classical control method.The automatic flight control systems of longitudinal direction include pitch angle,vertical speed,height and cruising speed control modes.The automatic flight control systems of side direction include roll angle,sideslip angle,yaw angle and lateral track control modes.The simulation results based on short-period or rolling motion model show that all the modes meet the performance requirements.To follow similar principle and present the situation where a plane flies,an experiment is carried out in this thesis.The comparison of the two results shows,because of the usage of limiters and full motion models,the changes of elevator,throttle lever,aileron and rudder are more reasonable and this fits in actual flight status of aircraft.The advantages and disadvantages of the designed modes can be judged from this.What's more,anti-disturbance tests on all control modes have been done.Simulation results show that the anti-disturbance ability of control modes of pitch angle,vertical velocity and roll angle are weaker.Then,the pitch angle and vertical velocity control modes and side slip angle control mode based on airspeed feedback are designed.The simulation results indicate that the newly designed modes have better instruction tracking ability and anti-disturbance ability.At last,by designing control laws and simulation,a conclusion is drawn that if we want control modes to have better instruction tracking ability and anti-disturbance ability,we had better not have each system work individually.It's better to let several systems work at the same time.