A simulation and scheduling method for analyzing the peak time capacity of the dual-robot in-line stocker

The automated material handling system (AMHS) plays a central role in realising smart manufacturing by providing manufacturing facilities with flexible, fast, and precise controls. This paper investigates a new type of AMHS known as the in-line stocker, which not only moves unit loads in manufacturing facilities under processing, similar to the automated-guided vehicle but also stores them on shelves, similar to the automated storage and retrieval system, which can reduce material handling space requirements. However, the traffic rate is very high inside an in-line stocker, and two robots are used along the single lane, which is the dual-robot in-line stocker (DRIS). This paper develops an analytical model to estimate the capacity of the DRIS based on a combined simulation and scheduling method. The simulation analysis shows that the model can be used not only to estimate the precise capacity of a DRIS but also to optimise its operating parameters.