Efficiency of Dummy Jobs in Robust Scheduling

Abstract

This study deals with robust scheduling approach, in which additional dummy jobs are inserted into the schedule in order to absorb impacts of machine breakdowns,urgent jobs and other uncertain events. In this paper, effects of those events are previously measured by the deviations of job starting and completion times on the actual schedule from those of the predictive schedule. We consider a suitable amount of dummy jobs to be inserted in order to minimize the deviation. Through computational experiments, the effectiveness of dummy jobs insertion is demonstrated by applying our method to single machine scheduling problems with due date and unexpected delays of job processing due to machine breakdowns.