Prescribed-time unknown input observer-based UAV attitude tracking control with uncertainties

External disturbances, inertia uncertainties, and actuator faults will greatly damage tracking performance of quadrotor unmanned aerial vehicles. In order to achieve high- precision attitude tracking control, a control method based on prescribed-time unknown input observer (PTUIO) is proposed in this paper. First, inertia uncertainties, external disturbances and actuator faults are regarded as lumped disturbances. Then a PTUIO is constructed to accurately estimate the lumped disturbance value within a specific time, and estimates are fed back into controller. One of the advantages of PTUIO is that upper bound of the disturbances and their derivatives do not need to be known priorly and estimate error arrives at zero within prescribed time. Second, based on state transformation, a prescribed-time controller is designed combined with a time scale function, which grows unbound toward prescribed terminal time, making tracking errors converge to zero within a prescribed time and improving convergence rate. Numerical simulations are performed to validate the effectiveness and robustness of the proposed control method.