Cycle time models for the bidirectional flow-rack AS/RS
Mohammed Hamzaoui, Zaki Sari
Abstract
This paper deals with the bidirectional flow-rack AS/RS (Automated Storage and Retrieval System). This system was recently introduced in the literature. In this paper, models that consider the system from a holistic aspect are presented in order to grasp its real systemic running. The adopted modelling approach allows obtaining closed form and easy to use equations that model the expected required time to carry out storage/retrieval transactions for the whole system. The paper presents derived continuous models for these transaction. These latter are easy to use to perform mathematical investigations, as optimization, throughput evaluation, systems comparison etc. However, they are not completely faithful to the real system behavior. This is why also discrete models were developed, which are much more accurate, and which were used as a benchmark to evaluate the accuracy of the continuous ones. To do so, a self-made software was developed, and results could be extracted and discussed.