**1. Introduction**

One of the key factors, which determine the level of competitiveness of manufacturing plants, is the ability to achieve flexible production and delivery of goods in accordance with customer requirements. Therefore, logistics and Supply Chain Management play an important role in market competition [1]. Logistic operations are carried out in two areas, internal and external to the organization. Therefore, the term "Intra-logistics" describes the organisation and realisation of internal material flow and logistic technologies as well as the goods transhipment in the industry, using technical components, partial and full systems and services [2].

In connection with the flexible production, there are also increased requirements regarding the flexibility and reliability of internal transport systems, associated with the production of short series of various products and thus requiring more transport operations [3]. In response to these needs, the Automated Guided Vehicles (AGVs) are used a lot more widely, which enables full automation of transport operations and can handle various transport routes using only computer navigation systems [4–6].

In order to evaluate the system's productivity, the use of Overall Equipment Efficiency (OEE) metrics has been proposed that is usually used for stationary resources, like machines. The aim of the paper was to prove the hypothesis that the OEE metric can also be used for transport facilities such as AGVs, and there is a dependence between machine and transport effectiveness.

To investigate the influence of the intra-logistic system over the performance of the manufacturing system we have developed a conceptual model of Flexible Manufacturing System (FMS) with an automated transport system with AGVs. The model of the FMS was built with the use of FlexSim software and the OEE metric was used for system integration and description of the availability, reliability and performance parameters for machines and vehicles. Then the Discrete Event Simulation (DES) method was used for performing the series of experiments and an analysis of results is presented in form of Overall Factory Efficiency (OFE) and Overall Transport Efficiency (OTE). Our previous works [7–9] show that the computer simulation of the detailed model of the production line with machines, operators and robots with reliability parameters allows better representation and understanding of a real production process which is important for early design and enables front-end planning.

The AGV parameters play an important role for FMS performance; therefore, literature review about FMS, AGV and logistics issues, are presented in the next section. The subsequent sections of the paper include description of the problem, modelling and simulation experiments, results analysis and discussion and final conclusions.
