Partial feedback two-stage compensator designs without coprime factorizability

The two-stage compensator designs for multi-input multi-output plants are investigated.We do not assume the coprime factorizability of models. We first show that even if we do not consider the coprime factorizability, the classical result of the two-stage compensator design holds. We then show other two-stage compensator designs, in which we consider partial feedbacks in the sense of input-output relations. We further give partial parametrization methods. Even so, the number of parameters are reduced from the previous result.