A distributed approach to job scheduling in a Flexible Manufacturing System

Several Flexible Manufacturing Systems (FMS) have been developed in recent years and it is likely that many more will be developed in the future. This paper presents a distributed approach to job scheduling in an FMS. Because of the characteristics of an FMS, the proposed model assumes that each machine tool (node) in an FMS is equipped with a general purpose computer capable of controlling the node and communicating with the other nodes in the system. At first the system is assumed to be operating normally and a linear programming model is formulated to solve the job scheduling problem. When the system malfunctions, the job rescheduling is based on a non-linear programming model. A strategy matrix is utilized and maintained at each node to monitor the system. All scheduling decisions are made in a distributed manner by each node in the network. Such an approach frees up the main processor for other task and is well suited for a large and complex manufacturing system. A simple hypothetical FMS is utilized to illustrate the formulation and the utilization of the proposed model.