Control-theoretic Analysis of the Lead Time Syndrome and its Impact on the Logistic Target Achievement

Abstract

The unawareness of production planners about the interaction of the logistic variables (actual and planned lead times, work in process levels, capacities etc.) often leads to problems while trying to improve the logistic target achievement. The Lead Time Syndrome of production control (LTS) represents one of these counterproductive actions, e.g., the aim of improving due date reliability by adapting planned lead times. The result is often an aggravation of due date reliability. The investigation of impacts on the logistic target achievement by the complex and dynamic variable coherences of the LTS requires transferring these coherences into control theory. In addition, the LTS chain reaction has strong similarities to a positive feedback loop of control theory. Thereby, even small system disturbances can lead to an increase in the magnitude of the perturbation. Control theory provides tools to model the behavior of dynamic systems and to avoid positive feedback by implementing appropriate countermeasures. The overall targets of this paper are to depict variable interactions in the LTS by means of control theory and to derive potential measures by investigating the similarities to the positive feedback loop. Consequentially, a more precise parameterization of the company specific production planning and control will be enabled. Moreover, the improved understanding of LTS variable correlations will enable the selection of situation-dependent measures to improve the logistic target achievement in scope of the LTS in the following steps of research.