Robust controllers for linear regulators

This paper presents a formulation and solution of a problem in the design of robust controllers. These controllers are realizations of solutions to control problems which remain solutions in the case of arbitrary perturbations in the problem data and the controller parameters. For the particular problem studied here, it is shown that arbitrary perturbations are admissible only in the feedback gains and perturbations in the problem data (system parameters) must be suitably restricted in order for there to exist robust solutions.