General Model Of Four-rotor Aircraft And Study Of Sliding Mode Control

Recent years,with the progress of electronic technology,the quadrotor play a variety of roles in modern life and perform different functions.Such as seaside search,patrol,surveillance,intelligence gathering in military.Meteorological examination,pesticide spraying,crop detection and map measurement in civil aspect.Study on the quadrotor is increasingly extensive,but the structure of most quadrotor is square.In the practical applications,such as the restrictions of the airspace and the carrying volume,for instance,the backpack structure of some special industry.Meanwhile,the square structure of the four-rotor aircraft above is a special case of the rectangular structure.The rectangular four-rotor aircraft is chosen as the controlled plant,and its mathematical model is deduced.Thesis study on a mathematical model of quadrotor with rectangular structure,it has the good versatility and universal significance,the square structure of the quadrotor above is a special case of the rectangular structure.The rectangular four rotor aircraft can meet the mission requirements of a specific flight space,and is different from the structure of the traditional four rotor aircraft.The three-dimensional translational motion process of a rectangular four rotor aircraft is analyzed.After that,the torque analysis of the three-dimensional rotation process of the vehicle is carried out,and the mathematical model of the rectangular quadrotor is established.The general model of a square four rotor aircraft can be obtained by deforming the mathematical model of the rectangular four rotor aircraft,which has a reference function for the research of the square four rotor aircraft.The rectangular quadrotor mathematical research model of sliding mode control algorithm,mainly studies the equivalent sliding mode control method and improved global sliding mode control method,through design the sliding mode controller and use MATLAB/Simulink to verify the correctness of rectangular quadrotor.On this basis,a variety of reaching laws are analyzed,and an improved fast reaching law method is proposed.An improved reaching law sliding mode controller is applied to the rectangular four rotor aircraft model,and the correctness of the method is verified by MATLAB/Simulink simulation.The reaching law of sliding mode is divided into two parts,from the sliding mode,the reaching law first play a major role,can speed up the system from the initial state at the time of the sliding mode,the system can respond quickly;close to the sliding mode,the reaching law second play a major role,slow down the reaching sliding mode speed,avoid the severe buffeting caused by inertia factors in the sliding mode region.It is proved by theory that the reaching law can converge to the sliding mode in the effective time and prove that it can converge to a steady state.According to the mathematical model of the rectangular four rotor aircraft,build the rectangle quadrotor entity,and verify the usability of the above three kinds of sliding mode controller through the aircraft,and the conclusion is drawn by comparing the test of three sets of flight test.