Networked control systems (NCSs) have been one of the main research focuses in academia as well as in industry for many decades and have become a multidisciplinary area. With these growing research trends, it is important to consolidate the latest knowledge and information to keep up with the research needs. In this paper, the NCS and its different forms are introduced and discussed. The beginning of this paper discusses the history and evolution of NCSs. The next part of this paper focuses on different fields and research arenas such as networking technology, network delay, network resource allocation, scheduling, network security in real-time NCSs, integration of components on a network, fault tolerance, etc. A brief literature survey and possible future direction concerning each topic is included.

Networked Control System: Overview and Research Trends

Dimensions of Reinforcement Learning

Design and Analysis ofFault-Tolerant Digital Systems: B. W. JOHNSON (Addison Wesley, 1989,577 pp., £41.35) The book provides an introduction to the important aspects of designing fault-tolerant systems, and an evaluation of how well the reliability goals have been achieved. The book is mainly oriented towards a final year undergraduate course on fault-tolerant computing, primarily with an implementation bias. In chapters 1 and 2, definitions and basic terminology are covered, which sets the stage for the remaining chapters, and provides the background and motivation for the remainder of the book. Chapter 3 provides a thorough analysis of fault-tolerance techniques and concepts. This chapter in particular is remarkably well written, covering the issues of hardware and information redundancy, which form the mainstay offault-tolerant computing. Subsequent chapters on the use and evaluation of the various approaches illustrate the principles as they have been put into practice. At the end of chapter 5, small projects that allow the reader to apply the material presented in the preceding chapters are included. The resurgence of interest in fault-tolerance with the emergence of VLSI is the theme of chapter 6, focussing on designing fault-tolerant systems in a VLSI environment. The problems and opportunities presented by VLSI are discussed and the use of redundancy techniques in order to enhance manufacturing yield and to provide in-service reliability are reviewed. The final chapter covers testing, design for testability and testability analysis, which must be considered during each phase of the design process to guarantee that resulting designs can be thoroughly tested. Each chapter is followed by a summary of the key issues and concepts presented therein, and a separate list of references, which makes it easily readable. In addition, there is a reading list with more comprehensive and specialised references devoted to each chapter. Overall, the book is well written, and contains a great deal of information in 577 pages. The book has a definite implementation bias, and draws considerably on the author's experience in industry, particularly reflected in the projects accompanying chapter 5. The book should be a useful addition to a library, and a suitable text to accompany a lecture course on fault-tolerant computing. R. RAMASWAMI, Department ofComputation, UMIST

Book Review: Design and Analysis of Fault-Tolerant Digital SystemsDesign and Analysis of Fault-Tolerant Digital Systems: JohnsonB. W. (Addison Wesley, 1989, 577 pp., £41.35)

Internet of things (IoT) is a promising technology which provides efficient and reliable solutions towards the modernization of several domains. IoT based solutions are being developed to automatically maintain and monitor agricultural farms with minimal human involvement. The article presents many aspects of technologies involved in the domain of IoT in agriculture. It explains the major components of IoT based smart farming. A rigorous discussion on network technologies used in IoT based agriculture has been presented, that involves network architecture and layers, network topologies used, and protocols. Furthermore, the connection of IoT based agriculture systems with relevant technologies including cloud computing, big data storage and analytics has also been presented. In addition, security issues in IoT agriculture have been highlighted. A list of smart phone based and sensor based applications developed for different aspects of farm management has also been presented. Lastly, the regulations and policies made by several countries to standardize IoT based agriculture have been presented along with few available success stories. In the end, some open research issues and challenges in IoT agriculture field have been presented.

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A Survey on the Role of IoT in Agriculture for the Implementation of Smart Farming

As we edge closer to the broad implementation of intelligent transportation systems, the need to extend the perceptual bounds of sensor-equipped vehicles beyond the individual vehicle is more pressing than ever. Research and standardization efforts toward vehicle to everything (V2X), technology is intended to enable the communication of individual vehicles with both one another and supporting road infrastructure. The topic has drawn interest from a large number of stakeholders, from governmental authorities to automotive manufacturers and mobile network operators. With interest sourced from many disparate parties and a wealth of research on a large number of topics, trying to grasp the bigger picture of V2X development can be a daunting task. In this tutorial survey, to the best of our knowledge, we collate research across a number of topics in V2X, from historical developments to standardization activities and a high-level view of research in a number of important fields. In so doing, we hope to provide a useful reference for the state of V2X research and development for newcomers and veterans alike.

V2X Access Technologies: Regulation, Research, and Remaining Challenges

In this paper, the use of Fast and Gigabit Ethernet in networked control systems is tested. Real-time traffic and non-real time traffic are integrated without changing the IEEE 802.3 protocol packet format. In a mixed traffic industrial environment, it is found that standard Gigabit Ethernet switches succeed to meet time constraints that Fast Ethernet failed to meet

Performance of Fast and Gigabit Ethernet in networked control systems

The use of networks for communication between electronic control units has increased in car industry over the last two decades. Several types of networks were developed for this purpose. In this study, Ethernet at gigabit speed is tested as a network for such system. The use of Ethernet helps integrating real-time control functions and non-real-time entertainment functions. Two main scenarios were simulated using OPNET. The fist one simulates pure control networks on board of a moving vehicle. The second scenario is the same as the first one with an added video load to simulate on-board entertainment. Both simulations were successful, as the end-to-end delays were below the maximum round-trip delays required by the system.

Ethernet-Based Car Control Network

In this paper, the use of fast and Gigabit Ethernet in advanced networked control systems is studied. Redundant control node scenario is the key factor for minimum down-time. Ethernet 802.3 protocol is tested without modification in frame format. Gigabit Ethernet succeeded to absorb the control traffic of several working machines while fast Ethernet could not.

Gigabit Ethernet for redundant networked control systems

Wireless Sensor Networks have been often used in the context of Greenhouse architectures. In this paper, an architecture is proposed for two Greenhouses based on Networked Control Systems. This architecture is IoT-based and built on top of switched Ethernet and Wi-Fi. Some sensors in the proposed architecture require a one-second real-time deadline. Riverbed simulations prove that there is zero packet loss and no over-delayed packets. An important contribution of this work is the design of a channel allocation scheme that prevents interference in this relatively large Greenhouse system. Another contribution of this work is the introduction of fault tolerance at the controller level. If one controller fails in one of the Greenhouses, the other controller automatically takes over the entire operation of the two-Greenhouse system. Riverbed simulations again show that this fault-tolerant system does not suffer any packet loss or over-delayed packets. Continuous Time Markov Chains are then developed to calculate the reliability as well as the steady state availability of the two-Greenhouse system. The Coverage parameter is taken into account. Finally, a case study is presented to quantitatively assess the advantage of fault tolerance in terms of downtime reduction; this is expected to be attractive especially in developing countries.

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A layered IoT architecture for greenhouse monitoring and remote control

This paper studies a Wireless Networked Control System which utilizes the IEEE 802.11b protocol without modifications to communicate between sensors and actuators in a production line environment. OPNET simulations are used to measure the end-to-end delay from sensor to controller and then from controller to actuator. It is observed that the measured delays, including all types of data processing, encapsulation, decapsulation and propagation, meet real-time control network requirements while guaranteeing correct packet reception. The system is then subjected to noise and several worst-case scenarios are analyzed. Simulations indicate that the system is still able to meet the required end-to-end delays. All results are based on a 95% confidence analysis.

Ramez M. Daoud

Papers

Performance of Fast and Gigabit Ethernet in networked control systems

Ethernet-Based Car Control Network

Gigabit Ethernet for redundant networked control systems

A layered IoT architecture for greenhouse monitoring and remote control

WiFi implementation of Wireless Networked Control Systems