A FRAMEWORK FOR THE EXACT EVALUATION OF EXPECTED CYCLE TIMES IN AUTOMATED STORAGE-SYSTEMS WITH FULL-TURNOVER ITEM ALLOCATION AND RANDOM SERVICE REQUESTS

We present a new framework for obtaining analytic expressions of the expected throughput rate in Automated Storage and Retrieval Systems (AS/RSs). The models developed consider generalized full-turnover item allocation policies and random storage and retrieval requests. Both single command and dual command operations are considered. A general expression for the expected cycle time in a single command class-based system is also developed. It is shown that some well known results are derived as special cases of our expression. These results provide for rapid performance evaluation of various operational policies in automated warehouses and in certain mass-storage information devices currently used by various computer systems. The potential for significant reductions in the expected cycle time is demonstrated in the case of full-turnover item allocation. © 1990.