Design of optimal disturbance cancellation controllers for polynomial output disturbances via loop transfer recovery

This paper discusses an application of the classical loop transfer recovery technique to the design of the optimal disturbance cancellation controller for the general polynomial output disturbances. The optimal output feedback controller is constructed based on the separation principle. The target of the design is chosen as the estimation error dynamics including the internal model for the disturbances. It is shown that the target feedback property can be recovered by using the weighting parameter in the performance index. A numerical example is presented to illustrate the design freedom provided by the proposed design procedure.