A Control System Design Of Small Unmanned Helicopter Based On Active Disturbance Rejection Control Technology

The advantages of small size unmanned helicopters not only reflect on low-speed,flexible take-off and landing as the traditional ones,but also can get rid of the physiological limitations of drivers,being able to carry out high-risk tasks in high strength without visual field limitation,so they are widely used in military and civilian fields.But the unmanned helicopter is a kind of complicated nonlinear control mechanical structure,it is difficult to establish a precise mathematical model.Furthermore,the strong coupling between the various channels of the unmanned helicopter causes a phenomenon that a lot of methods in modern control theory cannot be applied to the flight control system of small size unmanned helicopter.Besides,small size unmanned helicopters are sensitive to external wind speed and temperature,and are prone to generate safety problems during flight test.Therefore,it is very difficult to design an ideal flight control system,but it is extremely necessary.Based on the analysis above,firstly,according to the mechanical structure,the small size unmanned helicopter is divided into several modules to establish a simple mathematical model of small size unmanned helicopter by the knowledge of flight mechanics and rigid body kinematics.Then this thesis compares the advantages and disadvantages of the PID control algorithm and the auto disturbance rejection control algorithm and introduces the important parameters of the evaluation system.Then this thesis based on the method of self immunity designs a cascade controller of four channels: vertical,horizontal,yaw and height,which achieves the flight control system of size unmanned helicopter and improve shock problem of state observer algorithm of ADRC at the same time.At last,this thesis analyzes the flight control system which is based on flight control system of PID controller and auto disturbance rejection controller by the mathematical model established above.The results show that the latter not only has better control effect,but also can effectively solve the coupling problem between various channels.Then,the comparing between the old and new flight control system based on the improved ADRC shows that the improved flight control system solves the existing oscillation phenomenon well.At the same time,FlightGear software is used in this thesis to verify the feasibility and correctness of the flight control system based on ADRC,which provides a basis for the practical application of this system.