Simulation analysis of mini-load multi-shuttle automated storage and retrieval systems

Abstract

Technological developments in warehouses have changed processes of storage operations, which reflect in short response times of the storage or retrieval of goods, the reduction of stocks and the volume of storage work as well as the automation of the entire warehouse management. Many companies are replacing traditional warehouses with automated storage and retrieval systems, which can be classified into unit-load and mini-load systems. In this paper, the simulation analysis of mini-load multi-shuttle systems is discussed and evaluated. Multi-shuttle systems are based on the quadruple and sextuple command cycle and could therefore achieve higher throughput capacities due to single-shuttle systems. Different analytical models are used by practitioners for designing multi-shuttle systems. The problem arises with the selection of the appropriate analytical model for which the condition of minimal differences with actual circumstances in practice is fulfilled. For the evaluation of the two well-known analytical models, the discrete event simulations have been used. Beside the evaluation of analytical models, the results of simulation analyses showed throughput improvements for triple-shuttle systems according to dual-shuttle systems. The main objective of this paper is to determine the performance of presented models (analytical and simulation models) of multi-shuttle systems, which represents the main share and support in design process of mini-load multi-shuttle automated storage and retrieval systems.