Feedforward time-delay structures in state estimation: finite memory smoothing and continuous deadbeat observers

The paper investigates the possibilities of using a feedforward time-delay structure for state estimation and smoothing in linear continuous dynamic systems. A fixed-lag finite-memory smoother and a continuous deadbeat observer are shown to be described by a linear combination of delayed measurements of the system inputs and outputs. To facilitate implementation of the observer-based controllers an infinite-memory deadbeat observer is introduced. Design methods are illustrated by numerical examples