Position and attitude tracking control for a quadrotor UAV based on terminal sliding mode control

This paper investigates a novel control strategy for the position and attitude tracking control problem of a quadrotor UAV based on terminal sliding mode control. To realize the control objective, the model of the quadrotor UAV with six degrees of freedom which is actually a class of underactuated systems, is reasonably divided into a fully actuated subsystem with two degrees of freedom and an underactuated subsystem with the remaining four degrees of freedom. Firstly, two continuous controllers are developed for the fully actuated subsystem by means of the terminal sliding mode control to ensure that the yaw angle and the height of the quadrotor UAV can reach their desired values in finite time. Based on this, the underactuated subsystem can be further simplified as a four-order cascade system and achieve its goal using the same control method. It should be noted that the proposed control scheme is strongly robust to external disturbances and system uncertainties. In addition, compared with conventional sliding mode methods with sign functions, the chattering phenomenon is well attenuated via the proposed control strategy for it is continuous. Finally, numerical comparative simulation results verify the effectiveness of the proposed controllers.