Design of Cascade Control Structure for Stable Processes using Method of Moments

Abstract

In this manuscript, tuning rules are proposed for conventional series and parallel cascade control structures with emphasis on stable processes. Both primary and secondary controllers are assumed as proportional-integral (PI) type and are designed using the method of moments (MOM). In MOM, the controller parameters are computed by comparing the corresponding derivatives of the expected and actual closed-loop transfer functions at $s=0$. Moreover, equations relating closed-loop time constants and maximum sensitivity are also obtained. Despite of its simplicity, the proposed method yields robust and superior closed-loop performance.