Discrete-Time Equivalent Homogeneous Differentiators

Abstract

This paper proposes an entirely new discrete-time realization of an arbitrary order robust exact differentiator. Its construction relies on the redesign of the differentiator in the discrete-time domain by means of a non-linear eigenvalue placement. The resulting algorithm is consistent with the continuous-time algorithm and preserves the best possible asymptotic accuracies known from the continuous-time differentiator. In contrast to the existing discretization schemes, the proposed schemes are exact in the sense that in the unperturbed case the differentiators ensure vanishing estimation errors. Limit cycles typically present in the error state variables enforced by the forward Euler discretized algorithm are avoided and the precision is insensitive to an overestimation of the gains.