Nonlinear Extended State Observer Based Robust Control for Quadrotor UAV Trajectory Tracking with Input Saturation*

In this paper, the problem of robust anti-disturbance control of a quadrotor unmanned aerial vehicle (UAV) with input saturation and disturbance is investigated. A sliding mode trajectory tracking control method based on nonlinear extended state observer (NLESO) is presented. This approach first designs a NLESO for estimating all states and total disturbances in the quadrotor UAV. Then, a hyperbolic tangent function is introduced to approach the actuator saturation function. Combined with the traditional sliding mode control method, a second-order auxiliary dynamic system is adopted to compensate for the influence of input saturation. Moreover, the trajectory tracking capability of all signals of the closed-loop system is demonstrated by Lyapunov stability. Finally, quadrotor UAV model-based data simulation is presented to illustrate the theoretical results.