Simulation based performance analysis of an autonomous vehicle storage and retrieval system

In this paper, simulation based performance analysis of an autonomous vehicle storage and retrieval system (AVS/RS) is presented. AVS/RS represents relatively a new system for automated unit-load (UL) storage based on autonomous vehicle (AV) technology. This new system consists of AVs, lifts and storage racks. It is implemented at scores of facilities in Europe. The aim of this study is to find out near optimum values for number of AVs and lifts in the system that result in high performance under various pre-defined storage rack configuration scenarios. The storage rack of the system is defined in terms of number of aisles, bays and tiers. We consider seven rack configuration scenarios, ten and nine vehicles per zone and two arrival rates – 450 and 500 pallets/h. The performance measures considered are: average cycle time of storage and retrieval transactions, average utilizations of AVs and lifts. The simulation model of the system is developed using ARENA 12.0, a commercial software. We find that having a large number of lifts (zones) and a large footprint yield better performance.