Performance comparison of two material handling systems: AVS/RS and CBAS/RS

The purpose of this study is to compare the performance of two material handling systems (MHSs) – autonomous vehicle storage and retrieval systems (AVS/RSs) and traditional, crane-based, automated storage and retrieval systems (CBAS/RSs) – with respect to key performance measures. First, the two MHSs are simulated using ARENA 12.0, commercial software, via 198 experiments based on the rack configurations of the warehouses, number of storage and retrieval (S/R) devices and S/R transaction rates. Five performance measures are considered – average flow time, S/R device utilisation, average waiting time in S/R device queue, average number of jobs waiting in S/R device queue and cost. We also complete a paired-t test comparison to find out the best warehouse design based on cost, flow time and utilisation of the S/R devices. An examination of the results, specifically the flow time of the S/R devices, suggests that in many cases the AVS/RS performs better than the CBAS/RS. However, the best design, when the system costs are considered, is obtained with a CBAS/RS.