Design And Research Of A Small-scale Helicopter Having Three Rotors

In recent years,as a novelty in the field of Aeronautical products,multi-rotor unmanned aerial vehicle(UAV)is more and more applied to military and civil fields,which causes wide attention of researchers at home and abroad.At present,even-wing UAV represented by four-rotor is becoming more and more mature,but it still faces some key technical challenges,such as optimization design,power and energy issues.In this paper,a Tri-rotor UAV is designed by adding a rudder to the tail,the tail can be deflected around the arm to offset the tail reverse torque distance.Tri-rotor UAV is a new-looking and high-performance rotor aircraft.Compared with quadrotor UAV,it saves one motor and rotator,makes the structure of the UAV compact,reduces the weight of the body,and improves the lifetime.The main work of this paper is as follows:Firstly,this paper introduces the mechanical structure and rotor layout of the trirotor UAV,and then analyzes the force and torque of the tri-rotor drone according to the flying principle of the drone.The dynamic model of the tri-rotor UAV is derived by using Newton's Euler equations,and it is concluded that the output variables of the three-rotor UAV are highly coupled and have nonlinear characteristics.Then the trirotor UAV model is simplified based on the assumption including the small angle,the low-speed and windless operating environment,and the rotational inertia of the UAV is derived via the SolidWorks software.Secondly,this paper builds a tri-rotor UAV platform.The purpose of our design of the tri-rotor UAV hardware system is to analyze the influence of the position of the center of gravity of the tri-rotor UAV on flight stability.The selection of the motor and blades is determined by the load requirements of the drone.In this paper,the circuit system is designed,including the main controller circuit,attitude sensor circuit,remote control circuit,debugging circuit,etc.Subsequently,the software system of the tri-rotor UAV is designed,and the flight control software framework based on the real-time operating system is constructed,and the task control process is briefly introduced.Finally,the flight control schemes based on cascade PID and backstepping method are respectively designed according to the dynamic model of the tri-rotor UAV.This paper first uses the cascade PID algorithm to control the flight of the tri-rotor UAV,and the simulation through matlab verifies that the PID controller can basically realize the flight control of the tri-rotor UAV.In order to further improve the flight performance of the UAV,the paper proposes an attitude control scheme based on the backstepping method,and derives its control law through theoretical derivation.Subsequently,the control model is simulated,and the results verify that the backstepping method can quickly achieve the attitude tracking of the tri-rotor UAV,and the response is no overshoot.Finally,the effectiveness of the control scheme is proved by the flight experiment of the UAV prototype.There are 54 figures,1 tables and 62 references in this paper.