Partial Control: Reuel Shinnar's Impact On Control of Complex Chemical Systems

Many complex chemical processes having a large number of process variables and poorly understood models can be controlled reasonably well by controlling only a small subset of process variables using an equally small number of manipulated variables. This basic idea, termed "partial control", was originally proposed by Reuel Shinnar in 1981.   Knowingly or unknowingly, this idea has been and continues to be applied to successfully control numerous complex industrial processes. We present a number of terms such as process variable dominance, modelable responses, practical degrees of freedom and sufficiency of partial control. We demonstrate the applicability of these concepts with several examples.