Trajectory Tracking of UAVs Using Sigmoid Tracking Differentiator and Variable Gain Finite-Time Extended State Observer

The problem of quadrotor attitude and position control is considered in the presence generally lumped disturbances: external disturbances model uncertainty. improved active disturbance rejection controller (ADRC) for trajectory tracking proposed compensating disturbances. Firstly, sigmoid differentiator (ISTD), combining Sigmoid function sliding mode terminal attractor proposed, which can accelerate global convergence rate effectively reduce chattering. Secondly, a novel variable gain finite-time extended state observer (VGFESO) approach to estimate disturbances, while observation errors are convergent zero finite time. Then, super-twisting (STWSMC) utilized desired attitude. Finally, VGFESO closed-loop stability system proved. results show that time scheme shortest, integral absolute error ADRC reduced from 2.64 0.91. anti-disturbance capability fully illustrated when compared with robust adaptive nonsingular fast sliding-mode (RANFTSMC).