Linear-quadratic and γ-optimal output control laws

The problem of linear-quadratic control in the class of linear dynamic output controllers was solved, and the necessary and sufficient conditions for existence of the optimal controllers were formulated in terms of the linear matrix inequalities. The parameters of such controllers were proved to depend on the plant initial conditions, and the optimal controllers were shown to be unrealizable under certain initial conditions. The results of numerical comparison of the linear-quadratic and γ-optimal controllers were presented.