Gap metric problem for MIMO delay systems : parametrization of all suboptimal controllers

We consider the problem of robustness optimization in the gap metric for MIMO systems with a scalar time delay. We present an algorithm for the parametrization of all suboptimal controllers. In our algorithm the AAK theory plays the central role. Using this approach, suboptimal controllers can be found by computing solutions to certain infinite-rank operator equations. We show that these equations can be solved numerically by modifying the two-point boundary-value problem approach reported earlier for the computation of optimal robustness radius. We present a numerical example to illustrate the procedure