Robust fixed time controller with motor dynamics and composite disturbances for a quadrotor unmanned aerial vehicle

A fixed time robust control method is presented for trajectory tracking control of quadrotor systems with motor dynamics in the presence of unmodeled disturbances and external disturbances. The recommended control method avoids the negative effect to the quadrotor system caused by motor dynamic which is considered as first-order dynamic with dynamic disturbance. And fixed time extended state observer is adopted to estimate the composite disturbances and obtain the first and second derivative of desired trajectory and virtual control. Together with fixed time convergence control method, the stability and convergence characteristics of quadrotor system can be guaranteed. Finally, several simulations prove the effectiveness of the novel method with different time constants of motor dynamics.