The Study Of Control Algorithm For Small-sized Aerial Photography UAV's Flight Control System

Small-sized unmanned aerial vehicle(UAV)is a kind of aircraft with many attractive features,such as portability,high-maneuverability,high-security,high-reliability and low-cost.It has a wide application prospect in both military and civil fields.To meet the requirement of aerial photography in land survey,the control algorithm of small fixed-wing UAV with high speed and long endurance will be studied in this paper.In order to study control algorithm of the flight control system,UAV needs to be modeled.In this paper,small UAV(unmanned aerial vehicle)modeling method were studied.Associated aerodynamic coefficients of the Cessna Extra-300 fixed wing UAV for the project team are calibrated by using DATCOM combined with three-dimensional model.The non-linear model of the UAV is established by the method of mechanism modeling,and the linear model is obtained after trimming,decoupling and linearization.In order to satisfy the attitude stability requirement of UAV in land survey under various wind disturbance conditions,the control algorithm of UAV flight control system is studied.Based on the UAV model obtained in this paper,the control laws of pitch angle and roll angle are first designed by using PID control algorithm.And the simulation results show that the anti-disturbance ability of PID controller is weak.Based on the high stability requirement of the aerial photographic UAV and more airborne interference,the anti-disturbance capability of the UAV needs to be improved.Therefore,Hinf control theory is studied.The control laws of the pitch angle and roll angle are designed,and the anti-disturbance capability of the controller based on the Hinf control theory is simulated and verified.Finally,Semi-physical simulation experiments are taken based on the designed control law by using the hardware platform of the project team.The hardware platform of the project team is used to simulate the control law based on the design,and the simulation results show that it has good control performance and anti-disturbance ability.