# Towards a Flexible Smart Factory with a Dynamic Resource Orchestration
## 5 Literature Review
One of the key technologies for enabling vertical integration within a future Smart Factory structure is the Open Platform Communications United Architecture (OPC UA) communication protocol [33]. OPC UA is a major part of the interoperability model that has been chosen among the manufacturers, but unfortunately has not yet been developedas originally imagined. OPC-UA Companion Specification [34] needed to standardise the communication between manufacturing resources of various vendors is in the development status quo for some time now. Until these companion specifications are provided, the proposal is to develop a kind of administration shell for non-smart devices. It will also serve as a Communication Protocol and that way simultaneously serve as an admission and execution helper. Production flexibility is enhanced not only at the level of execution but also in the production planning, notably in the process-modelling phase [1; 35]. The dynamism of complex manufacturing systems will no longer be studied using contemporary modelling and simulation techniques. The new simulation systems must function as part of complex control systems, working in real-time and able to support decision-making and the creation of new knowledge [35]. Modelling and simulation will, therefore, be an integral part of the planning and control of the processes of factories of the future. A specific DSML can be designed for this purpose. The intent is not only to enable process and shop floor customisation but also to facilitate a supplementary visualisation of the process monitoring and graphical simulation of the entire production process model [12; 13]. An additional DSML and the tool for the support of resources modelling can also be created, in order that all factory assets can be used optimally and to collaborate efficiently. As application requirements grow alongside the evolution of SF solutions, the initially designed resource model will likely evolve as well. This DSML would allow updating and fine-tuning these resource models and could lean on the proposed KB for the representation of resources. While comparing contemporary and future assembly lines, the authors [18] stated that the current robots are not always capable of carrying out some of the tasks of high complexity that skilled human workers can do. Additionally, they are not so fit for high product customisation because of the lengthy time required for changeover and preparation for the production of another ordered product. As SF further evolves, the human worker will take on the role of the creative problem solver when confronted with complex problems inside the CPS [10]. Authors suggest that while in currently typical assembly lines humans work away from robots, in A4.0 they will work in direct collaboration with robots (so-called 'Cobots'). Treating and modelling all these production resources uniformly is a challenging task, especially when considering the much-desired orchestration of cooperation among the resources. One of the key roles in production resources coordination will most likely be created for a human worker whose primary function will be to lead a production strategy and manage the implementation of the self-organising production processes. A human worker will still supplement the adapted production lines of the future since his problem-solving skills and cognitive abilities and are still irreplaceable [8; 10]. Even though the human worker was considered in our previous papers [13; 19], it was referenced and elaborated only briefly. The formerly rudimentary form of the resources model has recently been extended and is presented in this paper in more detail. During production planning, humans will need to be treated as an equal CPS, but their broader existence makes them key players in future production systems [6; 16].