Communication architecture of an interactive assistance system for semi-automated manufacturing units
Résumé
When we wish to define computer architecture to control or to supervise a manufacturing system, it ends mostly in modular and distributed hybrid architecture. This architecture contains several levels, generally three: high, middle, and primary (or low). The high level is concerned with the general architecture of the control system, and is not concerned with the details of, for example, the communication issues with the equipments. On the other hand, the primary or first level is more specific in order to take into account various constraints like the multiplicity of the equipments and the means of communication among them (laser technologies, wireless technologies, connection to the network of the industrial unit). We can however isolate, in the upper level, subsystems which are relatively homogeneous from the point of view of their communications. This architecture of communication is essential for the efficiency of the system of control. It must be tailor fitted in the best way to the exchanges which are actually made by the system. Depending on the frequency of exchanges between various subsystems, the urgency of response, etc., it is possible to conceive more, or less, complex architecture. This situation led us to develop communication architecture for the control of manufacturing systems which leans on the Internet technologies, and more precisely on the HTTP protocol. The goal of our study is to set up a simple, efficient and reusable architecture based on well-known protocols for a simplified implementation. This paper reviews the architectures of control and their characteristics especially from the point of view of the internal communications required. Then, it expounds the various possibilities of implementation of middleware. Finally, it details the architecture that we developed on an example of control architecture applied to an assistance system for industrial units.