Workflow-based dynamic scheduling of job shop operations

Abstract

In a job shop such as a mould-making shop, dispatching decisions as to which job should be loaded on a machine when it becomes free are termed dynamic scheduling. A practical approach to dynamic job-shop scheduling is the use of discrete event simulation, and their dedicated simulation-based dynamic scheduling systems, often known as manufacturing execution systems or advanced planning systems, are available. In the present paper, we propose a workflow-based dynamic scheduling framework, in which a workflow management system (WfMS) serves as a dynamic job-shop scheduler. For this purpose, we have developed an algorithm for embedding a discrete-event simulation mechanism into a WfMS, and have implemented a prototype job-shop scheduler. Illustrative performance evaluation shows that the proposed framework is logically valid and computationally efficient.