Throughput performance analysis of Automated Vehicle Storage and Retrieval Systems with multiple-tier shuttle vehicles

摘要

This paper presents analytical travel time models for the computation of cycle times and throughput performance of Automated Vehicles Storage and Retrieval Systems (AVS/RS) with multiple-tier shuttle vehicles. The proposed analytical travel time models consider the multiple-tier shuttle vehicle with the condition of simultaneously travelling in a horizontal and moving in a vertical direction in the storage rack. Travel time models for single and dual command cycles of the AVS/RS with multiple-tier shuttle vehicles have been specified assuming uniformly distributed storage rack locations in the ith level of the storage rack and the probability theory. The proposed analytical models enable the calculation of the expected cycle time for single and dual command cycles, from which the performance can be evaluated of AVS/RS with multiple-tier shuttle vehicles. A simulation model has been developed for evaluation of the proposed analytical travel time models. Analysis of various types of AVS/RS with multiple-tier shuttle vehicles showed good performance of the proposed analytical travel time models.