Simulation-Based Optimization of Sequencing Buffer Allocation in Automated Storage and Retrieval Systems for Automobile Production

In production control with a stable order sequence, the assembly order is fixed in the form of the so-called pearl chain. However, parallelism and instabilities in the production process cause scrambling in the order sequence. The stability of the order sequence can be increased by using sequencing buffers between the individual production units. In the automobile industry, all sequencing buffers frequently share one large automated storage and retrieval system (AS/RS) with limited capacity. In existing approaches for dimensioning sequencing buffers, this shared capacity restriction is not considered, even though the optimal distribution of buffer capacity might be an important lever for increasing the sequence stability. Therefore, the focus of this paper is the identification of the optimal capacity distribution between several sequencing buffers using the same storage area. A greedy simulation-based improvement heuristic is developed which makes it possible to find promising solutions with a practical and intuitive optimization approach.