Robust balancing of straight assembly lines with interval task times

Abstract

This paper addresses the balancing problem for straight assembly lines where task times are not known exactly but given by intervals of their possible values. The objective is to assign the tasks to workstations minimizing the number of workstations while respecting precedence and cycle-time constraints. An adaptable robust optimization model is proposed to hedge against the worst-case scenario for task times. To find the optimal solution(s), a breadth-first search procedure is developed and evaluated on benchmark instances. The results obtained are analysed and some practical recommendations are given.

Keywords:

• assembly line balancing
• uncertainty
• robust optimization
• branch-and-bound algorithm

This research was financially supported by Saint-Étienne Metropole government and the European Project AMEPLM.

Without loss of generality, it is assumed that tasks’ order numbers in the graph of the precedence constraints are topologically sorted.

This research was financially supported by Saint-Étienne Metropole government and the European Project AMEPLM.

Without loss of generality, it is assumed that tasks’ order numbers in the graph of the precedence constraints are topologically sorted.

Acknowledgements

We thank Chris Yukna for his help in editing the English language used in this paper.