Robustness Analysis for the Re-entrant Flow Shop Problem

Abstract

Scheduling is required in almost every industry and when done well it can bring a lot of revenue. Flexibility is often forgotten when creating the initial schedules. Therefore, in case of an unexpected delay, the whole schedule has to suffer. In this paper, we consider a re-entrant flow shop with sequence-dependent setup times and relative due dates for our industrial partner, which specialises in industrial printers. Then, we perform a robustness analysis on real schedules from the industry, which can be extended to any system represented as a flow shop with relative due dates. We find how much time a schedule with relative due dates has before it becomes infeasible. We continue by empirically creating a new robustness measure and comparing it with state-of-the-art techniques. The experiments confirm that this measure can be useful in creating robust initial schedules for re-entrant flow shops with added idle time that has a minimal effect on the total duration of the solution.