Research On Robust Finite-time Trajectory Tracking Control Of Quadrotor

The quadrotor is a principal member of the small UAV（Unmanned Aerial Vehicle）.Because of its low cost and high performance advantages,it is favored by more and more researchers.However,in the actual military and civilian fields,since the quadrotor is a typical nonlinear and strongly coupled system,it is easily affected by the time-varying air resistance and the buffeting caused by the high-speed rotation of the four rotors during flight,and also suffers from effect on flight quality when the actuator is saturated,Therefore,the design of the quadrotor aircraft controller is very difficult and has important research significance.In this thesis,for the problem of robust finite-time control of quadrotor,the attitude tracking control of the system is studied.By combining nonlinear sliding mode control with adaptive algorithm and disturbance observer,the finite-time controller of quadrotor is designed.The main research contents are as follows:（1）Sort out the development stages of quadrotors,summarize the control algorithms that are widely used in quadrotors,then analyze the fuselage mechanism and flight principles of quadrotors,the classical mathematical model of quadrotor aircraft is established by Newton’s law and Euler angle transformation formula.（2）Considering the disturbance effect in the model,an adaptive terminal sliding mode controller is designed by combining the adaptive algorithm with the non-singular terminal sliding mode control for the inner and outer loop system of the quadrotor.By designing the adaptive law,the convergence speed of the sliding mode is increased,so as to effectively estimate and compensate the disturbance of the system,and ensure that the UAV can achieve stable attitude and track tracking control within a limited time.Finally,the simulation experiment of the quadrotor aircraft system is carried out through MATLAB software,and the expected effect is obtained.（3）For the attitude and trajectory system of the quadrotor aircraft,considering the influence of UAV input constraint,a saturation constraint function is introduced.By designing a secondorder auxiliary system,combining the finite-time interference observer and non-singular terminal sliding mode,an anti-saturation controller is designed.According to Lyapunov stability theory,the system can be stabilized in a finite time.Finally,the experimental results of MATLAB software confirm that the anti-saturation controller designed in this chapter can effectively solve the input limited problem of the quadrotor aircraft.（4）Considering the influence of external mismatch disturbance on the quadrotor aircraft,an integral terminal sliding mode controller based on a high-order finite-time disturbance observer is designed,which realizes the limited time tracking control of quadrotor.Finally,the effectiveness of the algorithm is verified by MATLAB software.In this thesis,for the quadrotor aircraft system,considering the influence of different external factors,multiple control algorithms are combined,the design of three different controllers has been completed,and all of them have achieved stable attitude and track tracking control in limited time.