Global Exponential Sampled-Data Observers for Nonlinear Systems with   Delayed Measurements
  This paper presents new results concerning the observer design for wide classes of nonlinear systems with both sampled and delayed measurements. By using a small gain approach we provide sufficient conditions, which involve both the delay and the sampling period, ensuring exponential convergence of the observer system error. The proposed observer is robust with respect to measurement errors and perturbations of the sampling schedule. Moreover, new results on the robust global exponential state predictor design problem are provided, for wide classes of nonlinear systems. 
Tarek Ahmed-Ali, Iasson Karafyllis and Francoise Lamnabhi-Lagarrigue
math.OC cs.SY