Robust output regulation for a class of coprime factor plant descriptions

A necessary and sufficient condition for robust output regulation is established for a class of linear MIMO (multiple-input multiple-output) systems. Using Youla parametrization of the stabilizer, the robust regulator problem is reduced to a second kind of model-matching problem. It is well known that this kind of model-matching problem corresponds to a two-block general distance problem, and a γ-iteration, procedure must be carried out to approximate the achievable minimum. It is shown that the second kind of model-matching problem can be reduced to an equivalent one of the first kind which has an explicit solution