Modelling and optimisation of single-cycle time for mobile rack AS/RS

ABSTRACT

This paper deals with mobile-rack automated storage/retrieval systems (AS/RS) that are a particular physical configuration of unit-deep AS/RS, i.e. the class of systems where each cell is designed to contain a single load. There are two main contributions in this paper: the first one is the analytical modelling of the average single-cycle time for mobile-rack AS/RS. The approach adopted for modelling is based on a continuous approximation, which is not recent, however, the approach proposed here for the transition from the discrete to the continuous models is different from those used previously in the literature. In a certain way, the multi-aisle and unit-load configurations can be seen as special cases of the mobile-rack configuration. This allows to deduce analytical models for the average single-cycle time for these two configurations from the one developed for mobile rack. The second main contribution of this paper is to find the dimensions of the AS/RS that minimise the average single-cycle time. The optimisation has been studied formally for the multi-aisle and unit-load configurations, and numerically for the mobile-rack configuration.

KEYWORDS:

• Materials handling
• automated storage
• modelling
• optimisation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data sharing is not applicable to this article as no new data were created or analysed in this study.

Additional information

Notes on contributors

Latéfa Ghomri

Latéfa Ghomri is She is currently a professor at the University of Tlemcen, head of the modeling and optomosation team of the Manufacturing Engineering Laboratory of Tlemcen (MELT). Her research interests revolve around the modelling and simulation of discrete event systems, applied to manufacturing systems.

Ali Rimouche

Ali Rimouche received the Ph.D. degree in partial differential equations in 2017 from the University of Tlemcen, Algeria. He is a member of the Dynamical Systems and Applications Laboratory and an associate professor in the Department of mathematics of Tlemcen University in Algeria. His interest areas are: nonlinear elliptic partial differential, variational methods, optimization problems related to industrial and manufacturing engineering, automated storage/retrieval systèmes and artificial intelligence.