2004 Volume 17 Issue 4 Pages 143-154
This paper presents a new hierarchical scheduling method for large-scale production systems which include a fault tolerance mechanism based on a hierarchical Petri net model. The automobile production system equipped with two stand-by lines is focused on as one of the typical large-scale systems with fault tolerance. In the high level, the FOHPN model is used to represent continuous flow in the production of an entire system, and MLD description is used to schedule the macroscopic behavior of the production system. In the low level, TPN is used to represent the production environment of each sub-line in a decentralized manner, and the MCT algorithm is applied to find a feasible semi-optimal process sequence for each sub-line. The proposed hierarchical scheduling method is confirmed through numerical experiments.