Disturbance observer-based robust trajectory tracking control for a quadrotor UAV

A robust trajectory tracking control law using disturbance observer is developed for quadrotor UAV. In the presence of exogenous aerodynamic disturbance and inner model parameter uncertainty,it guaranteed that the position and yaw angle could track the reference signal speedily and smoothly. An adaptive algorithm was designed for the position subsystem to suppress the mass uncertainty and disturbance force. A novel nonlinear disturbance observer was devised to observe the unknown disturbance torque. To track the intermediate command signal with an exponential convergence,the estimation of disturbance torque was added to the input. By virtue of Lyapunov theory,the global asymptotic stability of the overall closed-loop system was proved. Simulation results indicate that the controller is simple and effective,which has strong robustness to external disturbances and also has self-adaptive capability to uncertainty of load.