Research On Attitude Control Of Coaxial Aircraft

Compared with the traditional fixed-wing UAV,the coaxial double-rotor aircraft has the advantages of high hovering efficiency,compact structure and symmetrical aerodynamic characteristics.It can realize vertical take-off and landing in a small space,and has low demand for the site when landing.However,the system of the coaxial double-rotor aircraft has high complexity and strong coupling,which increases the difficulty of establishing the aircraft model.Domestic information on the establishment of the whole model and flight control is not rich enough.In view of the above problems,this paper studies the attitude control of coaxial double-rotor aircraft.In this thesis,the prototype design of the coaxial double-rotor aircraft was completed by the 3D modeling software.The prototype was assembled by machining and purchasing some parts.A six-degree-of-freedom mathematical model is established according to the kinematics and dynamics of the coaxial double-rotor aircraft,and the methods for acquiring the relevant parameters of the mathematical model are introduced.For the attitude calculation algorithm of the coaxial double-rotor aircraft,the three representation methods of the attitude of the aircraft and their respective advantages and disadvantages,as well as the working principle of each sensor are introduced.In order to improve the accuracy of the attitude angle calculation,multi-sensor data fusion is used.A complementary filtering algorithm and a Kalman filtering algorithm are designed.Aiming at the design problem of the attitude control system of the coaxial double-rotor aircraft,this paper comprehensively considers the advantages of the PID controller algorithm is simple and reliable,which the integral separation and anti-integration saturation algorithm are optimized to improve the system performance.In order to improve the control precision of the attitude of the coaxial double-rotor aircraft,the angular velocity control variable is added on the basis of the traditional PID algorithm,and the cascade PID controller is adopted to realize the system without overshoot control,improve system stability and anti-interference.The designed cascade PID attitude control algorithm is written into the embedded flight control system,and the coaxial double-rotor aircraft with the cascaded PID parameters have been set up for flight test.Simulation and experimental results show that the cascade PID control algorithm designed in this paper can effectively control the attitude of the coaxial double-rotor aircraft.