**Abstract.**

This paper consider control structure design using the information
given in the pole vectors. It is shown how the input and output pole
vectors are related to the minimum input energy needed to stabilize a
given unstable mode using one Single Input Single Output (SISO)
control loop. The paper also look at stable but slow modes which need
to be shifted further into the Left Half Plane (LHP) using feedback
control. Moving stable slow modes are accomplished with pole placement
and the results are interpreted in terms of Linear Quadratic Gaussian
(LQG) control.