Eigenstructure assignment by output feedback: the case of common open- and closed-loop characteristic vectors

A simple proof of an algorithm for eigenstructure assignment by output feedback is presented that allows naturally for the assignment of common open- and closed-loop characteristic vectors. The result is significant because the number of outputs plus the number of inputs required for arbitrary eigenvalue assignment may be reduced when some of the desired closed-loop characteristic vectors are common to the open-loop system. This is demonstrated by example