# The Future of Factories: Different Trends
## 3 Characteristics of Digital Factory
### From Digital to Smart Factory  
The design of an intelligent shop floor layer of a digital factory is related to the new concept of a smart factory. A digital factory is the key enabler of a smart factory for the next generation of a Factory of the Future. A smart factory connects the main actors of the supply chain (people, products, and materials) to realize seamless communication and integration (man-and-machine) for the smart manufacturing realization. The adoption of high-end manufacturing equipment (i.e., smart devices, industrial robots, and robotic arms) and the integration of well-established equipment with IoT devices and sensors allows collecting real-time data and information from the factory floor. Smart factory adds decision-making capabilities to the shop floor, and data collected from equipment is analyzed to improve the lowest manufacturing layer's production process. In the literature, many definitions of smart factories are given. A most inclusive one defines a smart factory as [23]: _\"a manufacturing solution that provides such flexible and adaptive production processes that will solve problems arising on a production facility with dynamic and rapidly changing boundary conditions in a world of increasing complexity. This special solution could, on one hand, be related to automation, understood as a combination of software, hardware and/or mechanics, which should lead to optimization of manufacturing resulting in reduction of unnecessary labor and waste of resource. On the other hand, it could be seen in a perspective of collaboration between different industrial and nonindustrial partners, where the smartness comes from forming a dynamic organization\"_. Authors highlight this system's potential to enable cooperation between industry stakeholders and the optimization of manufacturing processes. For a smart factory, the digital factory represents a necessary prerequisite for its enablement. A smart factory is, in turn, necessary for the development of the next generation of smart manufacturing. Within a smart factory, the digital factory's capabilities are improved by adding an extra layer that provides real-time data from the shop floor, thus simplifying the construction of faithful 3D models of the digital factory. The shop floor data collection enables the digital factory to better design models, improving accuracy as well as simulation results (see Figure 2). In implementing a Smart Factory system, the Internet of Things (IoT) plays a key role. IoT sensors' data sensing enables the digital factory to enrich virtual models with real-time data inferred from the shop floor. Sensing capabilities improve model accuracy as well as provide real-time statistics about the manufacturing process of the supply chain. A sensing layer links the smart factory with existing applications of digital factories. Figure 2: Digital Factory lifecycle. The Smart factory enables data sensing from the shop floor. Therefore, a smart factory requires both vertical interoperability between shop-floor automation devices and services, as well as horizontal interoperability between enterprises and cloud service platforms [24]. As an open challenge, the integration between smart and digital factory [25] requires to provide an interface between entities of the digital factories and IoT devices of the smart factory. The integration requires to guarantee semantic and functional interoperability between heterogeneous technologies. IT applications should be enabled to receive data from smart devices from the digital factory layer, process these data, and update the virtual models. From the smart factory layer, the devices should receive feedback produced by the digital factory to optimize the manufacturing processes and help to make better decisions. This requirement poses the challenges of enabling interoperability on three levels [26]: (i) data transfer protocols, (ii) semantic of data, and (iii) data presentation.