Robust scheduling of flexible manufacturing systems with unreliable operations and resources

Abstract

This paper addresses the topic of robust scheduling for flexible manufacturing systems (FMS) with operation interruptions and unreliable resources. The proposed approach uses timed Petri nets as a model of the FMS in uncertain environments. This model includes controllable and uncontrollable transitions. The unexpected firings of the uncontrollable transitions represent operation and resource failures and the risk to deviate from the scheduled trajectories. This paper proposes an anytime graph search algorithm with a new objective function that combines performance and risk. In addition, the graph search incorporates a new filtering mechanism that learns from previous runs and two node expansion strategies. The performance of the proposed algorithm is compared with that of another already existing algorithm. A running example and a case study from a real company illustrate the efficiency of the proposed scheduling approach.

Keywords:

• discrete event systems
• timed Petri nets
• uncontrollable events
• scheduling
• unreliable resources
• manufacturing systems
• graph search

Disclosure statement

No potential conflict of interest was reported by the authors.