Quadrotor Attitude Control based on Nonlinear Active Disturbance Rejection Control

The characteristics of non-linearity, strong coupling and vulnerability to external disturbances exist inherently in attitude dynamics system of quadrotor. In order to eliminate the influence of coupling during attitude channels and improve the anti-disturbance ability of controller, an attitude decoupling algorithm based on active disturbance rejection control (ADRC) is designed in this paper. By analyzing attitude dynamics equation, attitude coupling are divided into two parts: static coupling part and dynamic coupling part. A set of virtual control variables is introduced to decouple the static coupling part. The dynamic coupling part is taken as the internal disturbance which is estimated by a extended state observer (ESO) and compensated in the control law. Moreover, extended state observer can also estimate the external disturbances precisely. The simulation results show that comparing with PID controller, the ADRC controller has grateful performance in both decoupling control and anti-disturbance ability.