Another noteworthy overseas trend is the digital factory standard (IEC 62832). This specification is still in the draft stage and is not an international standard yet, but it is extremely innovative to digitize the whole factory and manage the virtual and real worlds in an integrated manner.
Table 1 Digital factory layer structure
layer | Explanation | Example |
1 | Metamodel world | Conversion rules, authentication methods, identification codes, naming rules, security, etc. |
2 | The world of reference models | Term dictionary, item list, evaluation model, activity model, object model, etc. |
3 | Digital world | Data, schema, relations, procedures, contexts, objects, etc. |
4 | Real World | Things, things, people, money, etc. |
Table 1 summarizes the various mechanisms of factories using the concept of layers. First of all, the layers of the real world correspond to what is happening here and there and the reality that exists. People’s conversations and analog processing are events in this real world layer. On the other hand, computers can handle the digital world. Here, a part of the real world is copied as data or signals (bits), and at the same time, it is integrated with the real world to change the reality itself.
The aim of the digital factory is to integrate this digital world with the real world as much as possible to create a cyber-physical system. The entire life cycle of a factory, such as design phase and maintenance phase, such as monitoring and control of production equipment and lines, as well as production phase, is the target, and by connecting them in cyberspace, the real world is linked.
Of course, it is not easy to actually build such a mechanism. This is because the real world is connected everywhere, beyond corporate boundaries. Therefore, in order to enable such efforts, a reference model that goes beyond the framework of a company is required. As shown in Layer 2 in Table 1, in the world of reference models, it is necessary to define an object model that represents the target object and an activity model that corresponds to the activity one by one.
In the international standard, instead of defining individual reference models, there are cases in which a model that is one layer higher than the reference model itself is defined, such as rules for creating reference models and rules for managing them. These are defined in Table 1 as the metamodel world. This allows each company to create its own reference model.
There is a PSLX platform specification6) as a reference model for manufacturing in Japan. By associating the object model and activity model defined here with digital data that is actually moving in an actual factory, it will be possible to link ICTs individually implemented on a business unit basis. For example, in the “Plant Whole Collaboration” demo held at Tokyo Big Sight in November, 2014 , software with unique data structures such as production planning systems, inventory management systems, schedulers, and MESs are flexibly linked on the PSLX platform. It has been proven that it can collaborate.
In addition to ISA-95 and PSLX, manufacturing reference models may exist in various regions and fields. It can be said that there is no single reference model in the world. However, even if there are various reference models in the same field, they are naturally deceived by the digital world that selects them, and as an ecosystem is formed, reference models naturally converge into several mainstreams.
Therefore, for example, by pouring a large amount of Japanese manufacturing genes into the PSLX reference model, the gene will be inherited by some of the globally winning reference models.
6) PSLX Platform Specification, APS Promotion Organization ( 2014 ) http://pslx.org/platform/
