Reacting to Scheduling Exceptions in FMS Environments

Abstract

Uncertainties in the production environment and modelling limitations inevitably result in operational deviations from schedules generated using predictive models. A production control mechanism monitors the environment for exceptions, and takes corrective actions, with the objective of adhering closely to planned objectives. This paper proposes a knowledge based (KB) methodology to perform such control in FMS environments. Use of KB techniques is motivated by the observation that control knowledge has a high heuristic content. A PROLOG implementation of this methodology, that generates automatic response to machine failures, dynamic introduction of new jobs, and dynamic increase in job priority, is presented. Experimental results appear to show that simple and generic design strategies for the KB can provide the basis for effective and robust control behavior.