A Multivariable Two-Degree-Of-Freedom Control Methodology

Abstract

This paper presents a two-degree-of-freedom design methodology based on a decoupling scheme. The proposed scheme is derived from the Youla parametrization and leads to a two-step design procedure. In the first step, a model-matching approach is proposed in order to set the desired nominal tracking objectives, while in the second step, μ-synthesis techniques are used in order to deal with the robust performance objectives. Special attention is paid to the robust tracking problem. For unstructured uncertainty, the most significant feature of the proposed design is that robust tracking requirements can be achieved, in a satisfactory way, by asimple H ∞ optimization. We carry out the design example on an ill-conditioned plant.