Discrete-Event Simulation in Distributed Manufacturing: Development of a HLA Adapter for Software Integration

Recently, the worldwide social and economic conditions evolved more and more rapidly, with the fashion of the fast technological changes, especially in relation to information and communication technology. This evolution happened without any appropriate infrastructure, capable to support the resulting development. The recent market conditions are the evidence of this situation: instability, deficits, and worker dismissals are just some common examples. Operating in these conditions is very difficult for the enterprises, which need to drastically reorganize themselves and sometimes are forced to give up.
The Distributed Manufacturing Systems can help to solve some of these problems. This organization paradigm gives the agility necessary for a rapid change to market pressures, taking advantage from one of the most important resources: knowledge. The distribution concept is the base for solving the market complexities. It allows redistributing responsibilities among several partners in order to keep the competitiveness. The net of relations and partnerships allows operating in the global market taking advantages from opportunities and avoiding risks. Adopting the Distributed Manufacturing System paradigm, the organizations can improve their autonomy, dynamism, reactivity, and especially flexibility, adaptability, and agility.
Specific characteristics of the organizations depend on the features of the adopted distributed system. Current researches pointed at different kinds of distributed manufacturing systems: Fractal Factory, Bionic Manufacturing System, Holonic Manufacturing System are some examples. Each one is different from the others on the base of the coordination, cooperation and competitiveness capacities. These manufacturing systems are evolving to a new organization paradigm: the Virtual Enterprise, which originates from joining different resources, such as workers, machines, and competencies, coming from different part of the world. Creating a Distributed Manufacturing System is one of the best solutions for surviving in the present economic situation. Managing this kind of systems can result very complicate. Discrete Event Simulation can help in the analysis of complex problems.
Simulation is the illustration of a system with its dynamic processes in an experimentation capable model in order to find solutions which are portable into reality (definition by VDI – guideline 3633). The term “simulation” is normally used to describe the process of executing a modelling program with user selected parameters and input data for simulating the future evolution of a system under prescribed conditions. Before a system can be simulated a model must be defined by abstracting the description of the structure and the behaviour from the real system.
Usually, the simulation is performed on the base of a unique whole model, which runs on a computer. This traditional method is not able to represent the actual organization and manufacturing systems, which are geographically distributed. The recent emphasis on distributed simulations is now changing the traditional approach to simulation programs; different computing platforms interact with each other over a network. This can offer a convenient way of combining existing software to represent more complex operating realities such as in the distributed manufacturing.
The emphasis on distributed simulation is often put on the reusability and interoperability of models. Thus, standards become important to ensure model compatibility. The use of the High Level Architecture can be very helpful in designing the simulation models for Distributed Manufacturing. This architecture has been developed in the nineties for military purposes, becoming a IEEE and OMG standard and applicable for civil use. Despite the potential advantages and the existence of an international standard, distributed simulation has not widely utilized yet in manufacturing. The reasons are typically related to the necessity of hard programming, standard software interfaces and lost of data and piracy risks.