Computer-based scheduling and resource conflict avoidance in assembly systems

In recent years, several research efforts concentrated on the control of assembly systems and were modeling them as discrete event systems, i.e. event-driven dynamical systems. These systems are characterized by the fact that the evolution of states is nearly completely depending on the existence of asynchronous discrete events. The research described in this paper uses this basis and focuses on the modeling and control of this kind of discrete event systems employing max-plus algebra and an innovative model predictive control scheme. A max-plus algebra based model predictive control scheme is introduced, which can be used to model and control flexible assembly systems. In a second stage, the control strategy is improved by means of appropriate constraints that allows to avoid resource conflicts or to minimize the inadvisable influence of such conflicts. The avoidance of resource conflicts increases the performance of assembly systems. The paper concludes with explanatory examples, which indicate the advantages and performance of the proposed novel approach.