Design Principles
Interoperability, virtualisation, decentralisation, real-time capability, service-orientation and modularity are the six design principles of Industry 4.0. Each of the principles is discussed in the sections below.
Interoperability
It is defined as ‘the ability to execute the same functions in the manufacturing of a product, even after the interchanging of machines and equipment takes place’. It gives a supportive surrounding in the manufacturing system by extending multiple networks [9]. It is the ability of two systems sharing knowledge and data and exchange information. Interoperability allows sharing of parts of software, business operations and application results throughout the process in the manufacturing system.
The structure of interoperability includes four steps: (1) operational, (2) systematical, (3) technical and (4) semantic interoperability. Operational interoperability shows the general structure of ideas, quality, languages and relations between the cyber-physical system and Industry 4.0. Systematical interoperability identifies the instruction and principles of methodologies, prototypes and standards. Joining of tools and platforms for technological development, information technology systems and related software comes under technical interoperability. Semantic interoperability makes sure that data is exchanged among various categories of people in various levels of the institution; also, malicious packages of applications are removed from the system. Industry 4.0 and CPS become more productive and cost-saving through these four levels of operation [10].
Virtualisation
Virtualisation refers to creating a virtual copy of real-time data. Virtualisation is used for establishing connections between machines and timely monitoring of the operations. The models used are connected to the sensor data. Virtualisation helps in notifying workers of failures of the manufacturing system so that safety precautions can be taken on time [9]. In a smart factory, the CPS create a virtual copy of the physical world, keeps a record of physical processes and make a decision on their own for the entire process.
A special form of a cyber-physical system is a virtual engineering object (VEO) or virtual engineering process (VEP). CPS merges the physical and digital worlds by creating networks globally in the industry that includes their machinery, production facilities and storage system. VEO is the actual representation of an object which through the experience captures, adds, stores, improves and shares knowledge. VEO can contain the ideas and experience of each crucial detail of an engineering object. VEO can store information which is used to make decisions so that operations can be performed in a better way. It is also useful in the areas of reliability, serviceability and maintainability of the product. VEP represents knowledge of all the operations performed and their sequences in the manufacturing process of a product and types of resources required in manufacturing. VEP determines the sequences for selected manufacturing operations. It also helps in selecting manufacturing resources to ‘convert’ a design model into a finished product economically and competitively.
To accomplish CPS for Industry 4.0, the main aspect is virtual simulation of goods and processes. In VEO/VEP all the crucial information of process planning is covered by modelling and simulation of manufacturing goods and processes. VEO/ VEP manages with self-organising manufacturing and control planning, and makes a strong bond between product life-cycle management, industrial automation and semantic technologies. Therefore, VEO/VEP is a special structure of CPS [11].
