SIAM Journal on Control and Optimization, Vol.45, No.5, 1898-1914, 2006
Output feedback pole assignment for transfer functions with symmetries
This paper studies the problem of pole assignment for symmetric and Hamiltonian transfer functions. A necessary and sufficient condition for pole assignment by complex symmetric output feedback transformations is given. Moreover, in the case where the McMillan degree coincides with the number of parameters appearing in the symmetric feedback transformations, we derive an explicit combinatorial formula for the number of pole assigning symmetric feedback gains. The proof uses intersection theory in projective space as well as a formula for the degree of the complex Lagrangian Grassmann manifold.
Keywords:output feedback;pole placement;inverse eigenvalue problems;Lagrangian Grassmannian;symmetric or Hamiltonian realizations;degree of a projective variety