Simultaneous pole assignment by multi-structured multirate sampled-data controllers—orthogonality consideration

Abstract

A new method of simultaneous pole assignment and simultaneous stabilization of h plant models Pj (j = 1, …, h) by multirate sampled-data controllers is presented. The method is based upon two key ideas. The first is the introduction of the ‘perturbation structure’ assumption on the plant models; i.e., it is assumed that a part of Pj is fixed for all j and the rest is changed completely. This assumption seems fairly feasible if Pjs are the models of a single object under different conditions or the models of many objects which perform the same function. The second key idea is the use of multi-structured multirate sampled-data controllers, which might offer a new horizon for a wide class of control problems other than simultaneous stabilization. The significance and feature of the proposed method in contrast with a previous method are clarified from the viewpoint of ‘controller-plant orthogonality’. Namely, we show that the resulting controller can be regarded as consisting of h subcontrollers each of which controls its target plant model but causes no feedback effect at sampling instants on other h—1 plant models.