Reactive repair tool for job shop schedules

Abstract

Reactive schedule repair is a better alternative to total rescheduling of impaired job shop schedules. For ease of implementation in the job shops, heuristic-based schedule repair methods are preferred. However, the majority of the repair heuristics reported in the literature are capable of handling only a singular disruption to the schedule. On the contrary, real-world job shops are subjected to multiple complex disruptions that occur randomly over the span of the schedule. A new heuristic, modified affected operation rescheduling (mAOR), has been successfully used for repairing a majority of typical job shop disruptions such as absenteeism of workers, process time variations and arrival of unexpected jobs using a combination of generic repair steps. In the present work, the mAOR heuristic has been applied for repairing randomly occurring multiple disruptions under rigorous shop floor conditions. The relationship between the variation of shop floor conditions and the performance of the schedule repair heuristic is investigated to substantiate the effectiveness of the mAOR heuristic. The results of extensive experimentation indicate that the performance of the mAOR heuristic is superior to the right shift rescheduling heuristic (a commonly cited repair heuristic). © 2005 Taylor & Francis Ltd.