“…The natural frequency is considered as the basis for a CPF because previous work has shown that, in some cases, it can be used as an effective proxy for a system's ease of control [e.g., Peters et al (2008); Hale et al (1985); Khot and Abhyankar (1993)]. The controllability Grammian matrix, W c , will be considered as the basis for a CPF because it has been successfully used for the location of actuators [e.g., Muller and Weber (1972); Roh and Park (1997); Lim and Gawronski (1993)]. Furthermore, it has been shown that, for some problem formulations, there is a relationship between W c and the coupling vector Γ v ].…”