Disturbance Rejection through Model Dependent Control

Model dependent control (MDC) is a combination of internal model control (IMC) and pole placement which, while preserving the advantages of IMC, gives improved disturbance rejection and allows operation at open-loop unstable steady states. Like IMC, it can handle time delays and inverse response. Usually only one parameter needs to be tuned and this directly controls the tradeoff between robustness and speed of response. In this paper it is shown how MDC can give excellent disturbance rejection without sacrificing the quality of response to set point changes, even when the disturbance poles differ from the plant poles. An example demonstrates this feature.