Automatic production control applying control theory

Abstract

A new dynamic production model for the planning level will be presented in this paper. The model is based on methods of control theory, which provide a large variety of appropriate tools for analysing and controlling dynamic systems. With the help of the funnel model and the theory of the logistic operating curve, a continuous flow model of a single work centre has been designed. For the control task a backlog controller and a WIP controller have been developed. The controllers interact to adjust the capacity and the input rate of the work centre so as to eliminate the backlog as soon as possible and to set the WIP to a defined level. By means of envelope curves of capacity flexibility, which are easily applicable to industry, the individual range of capacity adjustments at a single work centre can be modelled. Simulation experiments confirm that this concept ensures the synchronisation of capacity and work. The objective is to develop a closed-loop control for PPC with defined control and reference variables based on the logistical objectives.