Improved Cascade Control Structure for Controlling Unstable and Integrating Processes

Cascade control is an alternative to conventional single feedback control to improve the performance of a control system particularly in the presence of disturbances. However, so far published papers on cascade control strategies are for control of stable processes. In this paper, a new cascade control structure and controller design based on Standard forms are suggested for controlling unstable or integrating processes in a cascade control structure. Examples are given to illustrate the use of the proposed method and its superiority over some existing design methods.