The derivative estimation problem is addressed in this paper by using Volterra in-
tegral operators which allow to obtain the estimates of the time-derivatives with
fast convergence rate. A deadbeat state observer is used to provide the estimates
of the derivatives with a given fixed-time convergence. The estimation bias caused
by modeling error is characterized herein as well as the ISS property of the estima-
tion error with respect to the measurement perturbation. A number of numerical
examples are carried out to show the effectiveness of the proposed differentiator also
including comparisons with some existing methods.
