An ARMA model for a class of distributed systems

This paper presents an infinite dimensional ARMA model for infinite dimensional time-invariant linear systems in which the state transition operator is trace class. The ARMA model appears to be the natural extension of the finite dimensional ARMA model, and it is computed as the limit of a sequence of finite dimensional ARMA models. In a flexible structure example, numerical results are given for the ARMA models of both the open-loop plant and an optimal compensator.