The cost advantage of hysteretic controls for bi-level production systems

Frequently, production systems can be designed to be flexible in that the output rate of the system can be changed depending upon the demand requirements that the system faces. In such systems, the problem is considered to be the determination of the optimal point at which the system switches between its output levels. Simple control has one switching point between adjacent output levels. In this paper, it is shown that hysteretic control, the determination of two switching points, always provides for a lower operating cost than simple control. Based upon the characteristics of the performance measures, a procedure is developed that easily finds the optimal switching points. The procedure, when applied to a small midwest job shop, resulted in a cost savings of 9.97%.