An improvement of QFT plant template generation for systems with affinely dependent parametric uncertainties

Abstract

Quantitative feedback theory (QFT) is a powerful design technique for robust feedback control systems with plant uncertainties. In applying QFT to design robust feedback control systems, the generation of plant templates is an essential step. For a system with affinely dependent parameters and the parameter domain is a box, it is well known that the boundary of a plant template is included in the image of the set of edges of the parameter domain box. One can obtain the plant template from the image of the set of edges. However, this approach to the generation of the plant template leads to heavy computational burden since it wastes much computational effort computing the images of points on edges which lie in the interior of the plant template. In this paper, an efficient algorithm is proposed to identify, from an edge of the parameter domain box, the set of parameter points whose image lies in the interior of the plant template. The computational burden for generating the plant template thus can be obviously reduced by eliminating the identified sets of parameter points in the plant template generation procedure. Numerical examples are included to illustrate the efficiency of the algorithm.