Cycle time models for the bidirectional flow-rack AS/RS

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.

Multi-shuttle AS/RS dimensions optimization using a genetic algorithm—case of the multi-aisle configuration

“…One may clearly see that, for k e [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], the dimensions of t p and t v increase while those of t h decrease as the number of operations increases.…”

“…On the other hand, [10] succeeded in identifying the optimal dimensions of an AS/RS with a U-shaped gravitational conveyor and a single S/R machine that is based on a counting technique. In [11] these same authors applied accurate heuristic approaches to optimize the design of an AS/RS with a bi-directional conveyor with two S/R machines; one for storage and the other one for retrieval.…”

Multi-shuttle AS/RS Dimensions Optimization Using a Genetic Algorithm – Case of the Multi-aisle Configuration

“…One may clearly see that, for k e [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16], the dimensions of t p and t v increase while those of t h decrease as the number of operations increases. In addition, the approximate functions of t p and t h are determined with the least squares method, using the LeastSquares command in Maple.…”

Research on Optimization Strategy of Stacker Scheduling in Intelligent Storage System Based on Intelligent Improved Algorithm

“…Hamzaoui established a continuous model for a new two-way flow rack AS/RS system, and solved it after discretization. The simulation results show that this discrete modeling method can effectively evaluate the system throughput and other indicators [1]. Silva takes the storage location of goods as a constraint condition when modeling, and proposes a variable neighborhood search algorithm, which further improves the operation efficiency [2], Kaiwen Liu et al considered the problem of time cut-off when establishing the model, established a model with the minimum energy consumption as the goal, and used the gray wolf optimization algorithm to obtain the minimum energy consumption order sequence [3].…”