SIMULTANEOUS POLE ASSIGNMENT BY MULTI-STRUCTURED MULTIRATE SAMPLED-DATA CONTROLLERS - ORTHOGONALITY CONSIDERATION

A new method of simultaneous pole assignment and simultaneous stabiliz ation of h plant models P-j (j = 1,..., h) by multirate sampled-data c ontrollers is presented. The method is based upon two key ideas. The f irst is the introduction of the 'perturbation structure' assumption on the plant models; i.e., it is assumed that a part of P-j is fixed for all j and the rest is changed completely. This assumption seems fairl y feasible if P(j)s are the models of a single object under different conditions or the models of many objects which perform the same functi on. The second key idea is the use of multi-structured multirate sampl ed-data controllers, which might offer a new horizon for a wide class of control problems other than simultaneous stabilization. The signifi cance and feature of the proposed method in contrast with a previous m ethod are clarified from the viewpoint of 'controller-plant orthogonal ity'. Namely, we show that the resulting controller can be regarded as consisting of h subcontrollers each of which controls its target plan t model but causes no feedback effect at sampling instants on other h - 1 plant models.