Improved Sliding Mode Control for Robust Trajectory Tracking of a Quadrotor UAV

The problem of robust trajectory tracking control for a quadrotor unmanned aerial vehicle (UAV) with respect to parametric uncertainties and bounded external disturbances is investigated in this paper. The quadrotor dynamics are under-actuated, highly coupled and nonlinear, which make the control design problem challenging. Compared with the existing sliding mode control (SMC) methods, an improved SMC approach based on nonlinear sliding mode surfaces is developed in this paper to further reduce the controller parameters and maintain the trajectory tracking precision of a quadrotor UAV.