MIMO sliding mode and backstepping control for a quadrotor UAV

In this paper, tow nonlinear control approaches are proposed to solve the trajectory tracking problem for a quadrotor UAV in presence of external disturbances and model uncertainties. The first one is a sliding mode control which deals with the whole MIMO system despite most of the other approaches that divide the system into multiple subsystems. This method calculates four control laws which realize trajectory tracking of attitude and altitude of quadrotor. The second approach is a block-backstepping method that is designed for MIMO system. As the last part of this paper, position control of quadrotor based on the nonlinear dynamic model is designed using feedback linearization approach, which its combination with proposed sliding mode control or backstepping control gives full control of quadrotor. These control approaches are compared in different simulations and show good performance in tracking a desired path in Cartesian coordinate. They are also capable to deal with model uncertainties and external disturbances.