Abstract
In this paper a method for constructing a reduced order model retaining the internal structure of original high order cascade and feedback structured systems is derived by Mullis-Roberts algorithm.
A reduced order model obtained here is the optimal approximation in the sense that it minimizes the curvilinear integral of the squared norm of an approximation error at the unit circle of z plane. The algorithm for obtaining the reduced order models are described.
One feature of the proposed algorithm is that it is possible to compute reduced order models of each subsystem independently. The stability of the reduced order model is not always guaranteed. However, the rusults of numerical computations showed that the reduced order systems remain stable for almost all randomly selected examples and approximate the input-output behavior of original systems fairly well.
