m-Input m-output feedback control by individual channel design Part 1. Structural issues

Abstract

A new applications-oriented approach—individual channel design (ICD)—to multivariable feedback control for 2-input 2-output systems was presented and justified in a series of papers (O'Reilly and Leithead 1991, Leithead and O'Reilly 1991 a, b, 1992 a). This paper is the first part of a two-part investigation into the extension of the ICD framework, and the performance issues thereof, to general m-input m-output systems. The main results of this first part are fourfold. First, the ICD framework for general m-input m-output systems is justified for all multivariable system structures (RHP poles and zeros). In particular, it is shown that ICD on the original m-input m-output cross-coupled multivariable system is valid irrespective of the degree of cross-coupling. Second, the influence of (individual transfer function, channel, transmission) right half-plane zeros on controller design and closed-loop channel performance is elucidated. Third, the existence of fixed stabilizing controllers for uncertain m-input m-output systems is established. Fourth, it is shown how a separation of channel design tasks may be effected through invoking customer bandwidth specifications on different channels.