Finite-time extended state observer based sliding mode control for a VTOL multi-rotors UAV

In this work, we introduce a hierarchical controller that combines a finite-time extended state observer (FTESO) with a smooth sliding mode control This controller is designed to enable autonomous VTOL to accurately track trajectories even when faced with unknown aerodynamic disturbances. At the outset, the hierarchical control approach is employed to partition the flight control task into two distinct loops: the upper loop, which governs the management of the vehicle’s attitude, and the lower loop, focused on controlling the thrust force applied to the vehicle. Subsequently, a finite-time extended state observer is engineered to provide real-time estimations of unknown uncertainties and disturbances, with the capability to actively counteract and compensate for them within a finite time. Furthermore, a smooth sliding mode controller is developed and integrated with the finite time observer to guarantee the stability of the closed-loop control system. Finally, numerical simulation results are presented to illustrate the performances of the proposed observer-controller.