Modelling and controlling the dynamics of production systems

Abstract

Nowadays, in a fast-changing production environment, companies have to adapt their production structures rapidly. Therefore, new methods for production planning and control (PPC) are required that consider these dynamic changes. Today's PPC systems are mainly based on static models. Now, a dynamic production model has been developed applying methods of control theory. Using the funnel model and the theory of the logistic operating curve, a continuous model of a single production system has been developed. For the control task, a backlog as well as a work-in-process (wip) controller have been developed. The controllers interact to adjust the capacity and input rate of the work system to eliminate the backlog as soon as possible and to set the wip to a defined level. Simulation experiments confirm that this concept ensures the synchronization of capacity and work. In an ongoing research project, an extended model for several work systems connected via the material flow has been designed, which is based on the elementary one. A suggestion to integrate the strategy into PPC on the planning level has already been generated. The objective of this approach is to develop the present open-loop control realized in PPC into a closed-loop control with defined control and reference variables.