Finite time observer design for a class of nonlinear systems with unknown inputs

This paper proposes a novel nonlinear finite-time observer (FTO) for a class of nonlinear systems with unknown input. For this purpose, we extend the recent results of finite time convergent observer for nonlinear systems to the nonlinear systems that subject to unknown input disturbances, and conditions are also established to guarantee the finite time convergence of the estimation error dynamics. The estimate is recovered from the present and delayed estimates provided by two independent asymptotically unknown input observers (UIOs) in a predefined time. In particular, the finite convergence time τ can be assigned arbitrarily small. The obtained results are illustrated by considering a simple example system.