We present here a research approach for the calculation of the throughput rate for a physical configuration of automated storage and retrieval systems (AS/RS) called Multiple Aisles AS/RS (MA-AS/RS). These widely used systems are considered as a strategic division of warehousing, field that is considered as an important link in supply chains and logistics. In such discrete events system (DES) only one Storage/Retrieval machine (crane) is used for storage and retrieval operations, which has the advantage of decreasing the initial system costs (space and money) but at the same time has the disadvantage of reducing the system throughput. This important performances assessment parameter has significant repercussions on the whole system performances particularly in terms of efficiency and productivity.

For these fully automated systems we consider that the crane works under random policies i.e. bins are randomly situated for each operation and various functioning modes i.e. single command, double command and multiple command cycle. Thus, our approach is based on the calculation of the system throughput for each functioning mode using a strong and formal discrete modeling tool i.e. Timed Petri Nets (TPN).

Our contribution aims to: make a performances evaluation in order to improve studied system conception, completion and utilization, explore existing theory used to evaluate the performances of such DES and later try to make an optimization of the system dimensions. 

Key words: Multiple-Aisles AS/RS, performances assessment, throughput rate, Timed Petri Nets.