A parametrization of the discrete-time two-degree-of-freedom integral controllers with computation delays and its applications

Using the observer-based integral controller proposed by Isihara et al. as a basic controller, a state-space parametrization of discrete-time two-degree-of-freedom integral controllers of combined general computation delays. The proposed parametrization can easily be obtained by using the solution of an LQG problem for a plant but not for a higher-order extended system. In addition, the parametrization does not require constraints on the two free parameters. The role of the free parameters is clarified in connection with the basic controller. As applications of the proposed parametrization, the loop transfer recovery and the pole assignment using the free parameters are considered. A numerical example is presented to show the effectiveness of the proposed methods.