A generic Approach for the Industrial Application of Skill-based Engineering using OPC UA

Current trends in the context of Industry 4.0 attempt to minimize production costs and increase productivity. Nowadays control systems consist of components from various manufacturers. Therefore, it must be possible to easily connect these components without any platform specific interface definitions or software implementations. A first approach is the industry standard OPC UA, which enables the definition of hardware-independent interfaces of automation components (i.e. PLCs). Many manufacturers already start to integrate this standard into their products but unfortunately it only defines the transport layer of data and not which data is to be transported. Therefore, vendor-overlapping communication is only possible in case there is common understanding of how variables and functions are named and interpreted. A promising step towards this is to define skills as atomic unit for modeling and operating automation processes. Consequently the fixed mapping of skills and manufacturing stations is no more necessary during the engineering process. When applying skill-based engineering concepts it is only important to model and orchestrate skills that can accomplish the required tasks. The mapping between required and available skills can be done on the fly. Accordingly in this paper we propose an OPC UA-based multi-layered approach to orchestrate and execute manufacturing workflows using production task-based skills operated on flexibly linked and different hardware components (i.e. manufacturing stations).