ABSTRACT
Internal model control (IMC) is an attractive method for designing a control system if the plant is inherently stable. The method was first formally reported in C. E. Garcia and M. Morari. Since then, additional research results on this subject have been reported in journals and conferences. Independent reference input response and disturbance rejection can be achieved by adopting a two-degree-of-freedom IMC structure. In the IMC approach, the controller is easy to design and the IMC structure provides an easy way to achieve system robustness. For the MIMO case and for an in-depth treatment of IMC, readers are referred to M. Morari and E. Zafiriou. One limitation of the IMC method is that it cannot handle plants that are open-loop unstable. The method has been formulated using Laplace transform, and therefore is a frequency-domain technique. The concept is summarized for a single-input–single-output system.
