Question

Summarize the article of A review of industrial wireless networks in the context of Industry 4.0

Answer 1

Summary

A review of Industrial wireless networks in the context of Industry 4.0

Industry 4.0 has been attracting interests from researchers, governments and manufacturers since it offers smart production. An industrial wireless network (IWNs) is the key for industry 4.0. Due to advancement in Wireless sensor networks, smart factories and intelligent manufacturing system are being purposed. These smart factories will eventually offer a reduction in energy consumption, increase economic benefits and enable smart productions.

The Key element for IWN is a Wireless Sensor Network (WSN). The WSN has many applications in the field of agriculture, military, health, and other domains and hence attracting researchers and governments. In a WSN, the overall network contains a large number of ordinary nodes with each having a primary function for sensing physical parameters such as temperature, humidity, voice and other performances from the monitoring environment. Generally all WSN nodes are stationary, have limited power and don’t consider industrial environment since stationary nodes lack reliability, latency and flexibility. So, for industrial environment mobile nodes have been introduced to increase flexibility and mobility. Difference between IWNs and WSNs are Latency ( Monitoring the machine status and working environment) which is available in IWNs and is not provided by WSNs. IWN also provides mobility using the mobile nodes. The Environment in which IWN are operated is different from traditional environment (WSN) IWNs operate in a challenging environment(dust, vibration, heat, high temperature and humidity) i.e., in industrial domain.

Our Contribution:

1. Brief Layout of industry 4.0, its framework, the characteristics of inter-factory IWNs and the function of wireless modes are presented.

2. Quality of Service (QoS) and quality of Data(QoD) oriented architecture based on feature of industry 4.0 and IWNs

3. Application of IWNs

4. Challenges and issues of IWNs.

The Objective of Industry 4.0 is to provide smart industries which are energy efficient, uses green energy, are flexible, adaptable and efficient. It is basically industries communicating with each other located at remote places. The framework contains 4 major components: a physical layer containing machines, robots, mobile devices, a networks layer that can be created using cellular networks, wired network, wireless network to transmit real time data between different entities such as machine to machine (m2m), workmen to device or networks to data servers, The Cloud is the third component used for storing data and provides a bridge between the network and application layer. Last Component of Industry 4.0 is Application which is smart cities, smart enterprises and smart services.

We will now focus on the wireless communication to illustrate the framework of IWNs. IWNs have similar structure as of industry 4.0. The IWN communication can be divided into four components: smart entities, inter IWNS, beyond IWNs, displayers and servers.

Within IWNs, smart entities (such as workmen, AGVs, machines, ordinary sensors) with wireless transceivers could be regarded as wireless nodes. It is clear that IWNs are formed between nodes by wireless radios. Beyond IWNs, the access point nodes and the gateway create a bridge to other networks such as cellular, wired, internet and other public networks. Finally, higher-level data applications including data servers, management, controllers, and displayers, may be based on these specific networks. IWNs have obvious advantages that coincide with the requirements of Industry 4.0, so more and more industrial wireless solutions have been adopted within factories, particularly where moving devices are used or wired networks are not suitable.

A smart industrial wireless node not only contains memory modules, a processor, a power source, RF transceivers, and sensors, but also mechanical parts and related control and communication program. Moreover, in Industry 4.0, wireless nodes need to be smarter, more flexible and more mobile than traditional wireless network nodes. Compared with traditional wireless networks, industrial wireless nodes have higher capacities for processing, memory storage and energy. Meanwhile, with the development of IWNs, the scale of networks has become more and more complex. IWNs have a high number of mobile nodes and many particular requirements for an industrial environment.

Technical challenges in terms of their constraints, challenges and design goals for realizing IWNs 4.0 can be outlined as follows:

1. Dynamic Topologies - When mobile nodes are applied in industrial communication systems, it is obvious that the topology and link quality of the whole mobile WSN will dynamically change due to mobility, a hostile industrial environment, or node failures.

2. Signal Interference and path loss - Mobile nodes move along the ground following a certain path, so their antennas have a relatively low height and thus these mobile nodes are susceptible to absorption of the wireless signal. Furthermore, mobile wireless nodes will inevitably face interference due to elements of the harsh industrial environment such as heavy dust, metal obstacles.

3. Limited Energy - WSNs are still constrained by energy limits because wireless nodes are usually battery-powered.

4. Changing location - The parameters of individual mobile nodes (such as their location, pathway, residual energy and so on) may be preconditions for completing other functions.

5. Physical collisions and barriers - When increasing numbers of mobile nodes are applied in the industrial domain, it is unavoidable that physical collision will happen between mobile nodes, equipment, workers and other barriers.

In Industry 4.0, data (or information) and wireless communications is transmitted through IWNs. s. Big data, industrial clouds, and industrial systems are used in Industry 4.0 to increase productivity, reduce cost and energy consumption, and enhance flexibility and personalization. a. The data carries important information for the factory, services, manufacturing, and users and wireless communication is responsible for transmitting and receiving this data. Therefore, a new IWN architecture will be introduced, which aims to meet the demands for diversity and specificity of industrial applications.

QoS and QoD-oriented architecture of IWNs are configured for QoS and QoD of the entities. The entities are the foundation of the whole architecture, and include factory entities, networks facilities, and service equipment. The QoS indexes include real-time, reliability, longevity, security and privacy controls. The QoD performance covers validity, accuracy, reliability, and integrity. Furthermore, QoS and QoD are influenced by each other. IWNs are not an exception; many studies have divided the IWNs into a physical, medium access control (MAC), routing, transporting and application layer. However, this traditional layer architecture cannot satisfy the increasing requirements for different applications which are arising from the continuous development of technologies. To address these challenges, the concept of a cross layer design has been proposed and successfully implemented. However, there are new QoS requirements that need to be satisfied for different IWNs in the industrial domain. QoS of IWNs includes real-time, reliability, longevity, security and privacy criteria. To meet these QoS criteria, the design needs to be considered throughout all layers. As IWNs have developed, more and more companies and alliances have invested in these domains. Many architectures and industrial protocols have been proposed, including Wi-Fi, ZigBee, Bluetooth, RFID, and other proprietary protocols.

WSNs have been applied in smart plants, industrial environment monitoring and automation factories for low latency wireless communication. Therefore, WSNs in industrial applications can be used to provide an example for IWNs. Real-time performance is an important index for the industrial QoS. Furthermore, communications between wireless nodes require low latency to improve productivity. Many researchers have presented their methods to achieve good real-time performance from different views and layers of wireless networks. Most of these studies have achieved low latency by improving the routing, MAC, or transport layers or by using cross-layer mechanisms. The authors in have introduced a new traffic scheduling algorithm that focuses on the industrial applications of WSN for real time services, based on a window scheduling algorithm and the IEEE 802.15.4 framework. In al the other papers various protocols are proposed.

Data quality is an important factor for wired networks, especially for the internet. However, since most of the data in traditional IWNs is collected to solve special problems, monitor parameters, and deliver machine instructions, the overall system does not have a requirement for high quality data or information. However, for Industry 4.0, almost every workflow relies on high quality data and precise information and data is becoming a primary component of a successfully operating industrial system. Validity, accuracy, reliability, integrity.

factory frameworks is to establish a new platform and bridge that will support the manufacturers and users, and realize wireless communication among smart devices, workers and users while offering the advantages of flexibility, no wiring, and mobility. Thus, our smart factory prototype is based on IWNs, the cloud, smart machines and a management system.

The working principle of the overall prototype consists of several steps. Firstly, users customize their products of interest using the web page, and then related information about the user and the products are uploaded to a server. Once the raw information is obtained, the private cloud then builds a machine processing program, process, and resource utilization strategies, which are issued to the smart machine, workers, and conveyance system to finish the product manufacturing by IWNs. At the same time, manufacturing data and information about the user’s interests are transmitted to the industrial private clouds. Additionally, the related data and graphics are distributed to terminals for management and user validation and decisionmaking. In this case, there are two flow systems supporting the prototype system under normal operation. Firstly, from a physical view, the conveyance system is responsible for transporting the products. Secondly, from an information view, IWNs play an important role in the whole system. In contrast with traditional industry systems and factory, huge amounts of data will be produced during processing, and more and more information needs to be transmitted and processed by IWNs under the new challenges of Industry 4.0. Information is the basis to perform tasks for the whole system. However, multiple devices, network interface and communication protocols between the raw product, machines, workers and robots are needed to converse and communicate. As discussed above, IWNs provide the bridge and information communication. They are the foundation and key for realizing Industry 4.0 and smart factories.

Challenges and Issues

1. Reliability and topology control - In IMWSNs, the network consists of hybrid (mobile and static) nodes or only mobile nodes instead of static nodes. Therefore, it is necessary to present an effective way to deal with problems such as dynamic topology and reliability caused by the mobility.

2. Error tolerance - It is known that the error tolerance directly impacts the success of communications.

3. Quick handoff - When a WSN contains mobile nodes in an industrial scenario, the designer needs to consider quick handoff for real time and seamless handover, which may be required between different multiple access points, neighboring nodes, the base station, or sink nodes.

4. Node deployment/placement, Communication protocols

5. Efficient energy management - For Industry 4.0, energy consumption minimization and efficient energy management is the key to producing products and prolonging the network’s lifetime.

6. Data fusion

To Conclude: IWNs are a promising technology which will play an increasingly important role in the next generation of industrial systems for Industry 4.0. A QoS and QoD oriented architecture, existing solutions for QoS, and QoD are discussed in detail. Despite advances in these areas, there are many challenges that still need to be addressed within the Industry 4.0