General solution of robust tracking problem in two-degree-of-freedom control systems

In this note, we study linear time-invariant multivariable systems with two-degree-of-freedom compensators. First, we give a new parametrization of all stabilizing compensators from the viewpoint of independent design of transfer function and robustness property. Second, utilizing this parametrization, we solve a general robust tracking problem including the case of nonsquare plants, and show that "tracking" and "robustness" can be independently specified in two-degree-of-freedom control systems.