On System Representations and Discrete-Time Models of a Multivariable System

In the first part of this paper, some of the better ways of representing discrete-time systems, than the conventional discrete equations and the z transfer functions, are studied from the controller design and real-time computation points of view. Among those considered, the ¿ operator and the Euler operator forms are recommended. In the second part of the paper, a definition of discrete-time models for a multivariable continuous-time system and related important theorems are presented. Some popular discrete-time models are expressed in state space form which is convenient for computer calculation. Associated controllability, observability, and other characteristics of these discrete-time models are studied as well.