Diagonal balanced truncation of discrete delay systems

A new model reduction method is presented for discrete delay systems, where the reduced system is also a discrete delay system of a smaller size in th e dimension of the state. Traditional model reduction approaches to discret e delay systems are based on transforming delay systems into non-delay equi valent systems. However, when the state delay is large, they are computatio nally demanding. The proposed model reduction method can be efficiently com puted irrespective of the state delay. To do this, a diagonal balanced real ization is proposed based on block diagonal gramian-like matrices, and prop erties of truncation of the diagonal balanced realization are investigated. (C) 1999 Elsevier Science Ltd. All rights reserved.