Numerical differentiation using high-gain observers

High-gain observers have been used in nonlinear control to estimate the derivatives of the output. In this paper, we study discrete-time implementation of high-gain observers and their use as numerical differentiators. We show that discretization using the bilinear transformation method gives results better than other discretization methods. We also show that many of the available numerical differentiators are special cases of the bilinear discrete-time equivalents of full-order or reduced-order high-gain observers