IMC-based control system design for unstable processes

This paper studies an internal model control (IMC) based single-loop controller design method to find the feedback controller in either proportional-integral-derivative or high-order form for unstable processes with time delay. The performance limitation of implementing the IMC controller in an equivalent feedback structure for an open-loop unstable process has been addressed. The proposed method is generally applicable to a wide range of unstable processes and can be made automatic for online tuning.