Internal stabilization and decoupling in linear multivariable systems by unity output feedback compensation

We consider the problem of internally stabilizing and simultaneously diagonally decoupling a linear multivariable system by unity output feedback compensation. A sufficient condition is derived for the existence of a cascade proper compensator such that when employed in a unity feedback loop involving the proper transfer function matrix Poof a free of unstable hidden modes system , will not only internally stabilize the feedback closed-loop system but will also give rise to a closed-loop transfer function matrix , which is nonsingular, diagonal, and has desired poles. Based on this analysis, an algorithmic procedure for the computation of such a compensator is presented.