The zeros of linear optimal control systems and their role in high feedback gain stability design

The finite zeros of the open-loop transfer function matrix of the optimal controller of the multiinput time-invariant regulator problem are found to be the eigenvalues of a negative real matrix. The infinite zeros of the transfer function matrix are all real. Using the root loci technique recently developed for multivariable systems, these properties of the zeros provide means of designing stable, not necessarily optimal, high feedback gain systems under significant parameter uncertainty.