Optimal partitioning of vertical zones in vehicle-based warehouse systems

Abstract

New innovations in warehouse automation systems such as autonomous vehicle-based storage and retrieval (AVS/R) system offer greater flexibility and responsiveness in processing unit-load storage and retrieval transactions in high-density storage areas. To optimise system performance, new technologies should be implemented with optimal setting of design parameters. This research is a first attempt to model a ‘zone-captive’ AVS/R system and understand the effect of number and boundary of vertical zones on system performance measures. Further, we also analyse the effect of aisle orientation within a tier on cycle times. A detailed simulation model of a multi-tier zone-captive system is built to capture the dynamics of the system i.e. interaction among the vehicles, lift and incoming transaction requests, and estimate the performance measures of interest. The numerical experiments show that the transaction cycle times can be reduced by 1–12% with optimal partitioning of vertical zones and further reduced by 0.2–15.0% by a better aisle orientation.