Research On Trajectory Tracking Of Quadrotor UAV Based On Sliding Mode Control

With the application of quadrotor unmanned aerial vehicles(QUAVs)in many fields,the research of quadrotor aerial vehicle has attracted more and more attention from scholars of various countries.Among the numerous studies on QUAVs,the research on the trajectory tracking control algorithm of QUAVs has always been a difficult problem.At the same time,the QUAV is a nonlinear system with strong coupling.In most of the existing researches,the inner and outer loop control structure is applied and the desired roll angle and pitch angle are obtained by decoupling.In order to avoid the unknown factors in the process of decoupling and better accomplish the trajectory tracking control of the QUAV,our researches on the whole control system model are divided into two parts: fully actuated subsystem and underactuated subsystem.The main research contents are as follows:(1)The traditional sliding mode control strategy is used in the controller design of the fully actuated subsystem of the QUAV.And the designing controller of the underactuated subsystem adopts the second-order sliding mode control strategy.In addition,the QUAV controller is derived based on Lyapunov theory,and the controller can ensure that all system state variables reach and converge to the desired value,thereby realizing the trajectory tracking control of the QUAV.Finally,simulation and experimental results verify the effectiveness and robustness of the proposed controller.(2)In real control process of the QUAV,the system state has to converge to the desired trajectory in finite time,but the traditional sliding mode control has the problem of infinite time convergence.In order to solve the problem of infinite time convergence of the system,a controller with finite time convergence is designed by using terminal sliding mode control strategy.As the same time,with the strategy of terminal sliding mode control,the convergence speed of the system becomes slower when the system is far away from the equilibrium point.In the case,the fast terminal sliding mode control strategy is used to design a fast convergence controller by combination with the control design method form second-order sliding mode.Finally,simulation results and experimental results verify their advantages and shortcomings of controllers,and demonstrate the stability and fast convergence characteristics of the system under the above control strategies.