Robust stabilizing modified repetitive controllers for multiple-input/multiple-output time-delay plants with specified input-output characteristic

The modified repetitive control system is a type of servomechanism for a periodic reference input. When modified repetitive control design methods are applied to real systems, the influence of uncertainties in the plant must be considered. In some cases, uncertainties in the plant make the modified repetitive control system unstable, even though the controller was designed to stabilize the nominal plant. Recently, Chen et al. proposed the parameterization of all robust stabilizing modified repetitive controllers for multiple-input/multiple-output time-delay plants. However, using their method, it is complex to specify the low-pass filter in the internal model for the periodic reference input of which the role is to specify the input-output characteristic. Because, the low-pass filter is related to four free parameters in the parameterization. To specify the input-output characteristic easily, this paper proposes the parameterization of all robust stabilizing modified repetitive controllers for multiple-input/multiple-output time-delay plants with specified input-output characteristic such that the input-output characteristic can be specified beforehand.