Characterization of decoupling structural zeros of Rosenbrock's polynomial matrices

The problem of structural controllability has been widely investigated by many authors in the last decade. Their attention has been focused on systems described by state variable equations. This paper gives a complete characterization of input-(output-) decoupling structural zeros of systems described by Rosenbrock polynomial matrices. The known results for structural controllability (observability) of state space variable representation can easily be derived as particular cases. The generality of the approach presented is supported by the efficient tools of digraph theory