Cyber-Physical Systems Characteristics, Performance and Interactions In cyber-physical systems it is essential not to regard the computer as just a black box that executes programs by magic. The cyber layer encompasses those processes in the digital world of information technologies (IT) that do not require real‐time response, where human operators can perform the role of supervisors. The emergence of new technologies is providing new ways to compete in the current context of changeable and unpredictable market requirements. These processes in the digital world are named cyber‐physical processes. This is the case of many consumer electronic goods, being a washing machine a typical example. Table 2 compares these sector‐based criteria and assign a threshold in the level of automation to categorize these (semi)autonomous transportation systems as CPSs. Many control applications tightly coupling cyber and physical processes are composed of programmable controllers not necessarily embedded or hidden into the physical components. Research advances in Cyber Physical Systems (CPS) promise to transform our world with systems that respond more quickly, are more precise, work in dangerous or inaccessible environments, provide large-scale, distributed coordination, are highly efficient, augment … Then, we decompose these subsystems in their constituent components with their subsystem interactions, giving a more detailed description of the particular processes. Hazard analysis and safety requirements for small drone operations: to what extent do popular drones embed safety? Human safety is also a matter of concern in the physical processes governed by CPSs. In this way, the environmental deviations eventually disrupting the system could be traced back to their external causes, following the causal chains across different systems with several stakeholders involved. The Telemetron ASV is equipped with radar sensors and an automatic identification system (AIS), the latter being the integration of a satellite navigation system with an inertial navigation system. In most cases, however, sensors and actuators do not have sufficient computation and communication capabilities to close the feedback control loops in cooperative tasks. Which are the key features of CPSs and their relation with other system types? Particularly, control mechanisms through sensors, real‐time communications, programmable controllers, and actuators compose this category of cyber‐physical processes. In return, the cyber layer can respond by sending information flows to the programmable controllers or directly to the actuators, allowing trading control capabilities in established cases. These types of cyber‐attacks disrupting physical systems require broadening the scope from security and privacy in CPSs67 to consider the potential for physical harm and the implications for safety.27, 68 This broader view stresses the need for a combined safety and security risk analysis in CPS, where security and safety goals coexist and require an integration process.15, 69. The full text of this article hosted at is unavailable due to technical difficulties. In this figure, the operators are human controllers that (1) collect information of the process under control, (2) use information to make decisions according to models and procedures, and (3) implement control actions to influence the process under control. Finally, there is some degree of overlapping between the fields of CPSs and the IoT.34, 39 Mainly, some CPS applications are being connected to the Internet to use data‐accessing and processing services .10, 40 Thus, we establish a category of CPS‐IoT from the intersection of these two fields, namely, those CPSs built from ESs that include Internet connection in their network configurations. If you do not receive an email within 10 minutes, your email address may not be registered, The CPS master diagram considers a CPS as a system of three interacting layers. The notion of CPSs is a class of engineered systems grouped by a set of key features. Cyber-Physical Systems (CPS) comprise interacting digital, analog, physical, and human components engineered for function through integrated physics and logic. To conduct these operations, the human should be trained and properly informed of the protocols to follow under different circumstances. With the development of open communications and increasing levels of automation for vehicles, these features become even more important for safety. Unaware or manipulated operators could also be the gateways leading to cyber‐attacks. Conversely, at level 5, all the driving tasks are managed by the autonomous driving system. For completeness, the CPS master diagram includes the energy and information flows exchanged between the cyber and physical environments of the system. This representation serves as a first step toward a combined safety and security risk analysis, providing a generalized diagrammatic illustration of CPS architectures to represent different CPS applications. From a sector‐based criteria of autonomy levels (AL),73 we categorize this system as AL4: human on the loop‐operator/supervisory. Thus, these processes can be diagrammatically located in layers of the system, controlling particular sets of information and energy flows. Synthesis of the findings in a comprehensive schema which visually distinguishes between technological characteristics of CPSs and operations management characteristics, to build future CPS-based smart factories. These two sources of risk are different in motive (ie, unintentional and deliberate) and require a comprehensive approach to prevent or mitigate their potential safety‐related consequences. Even if the water treatment plant was not considered a CPS at the time and may not share all the CPS features, this cyber‐attack raised awareness of the security vulnerabilities in critical infrastructures and the potential for physical harm.51. On the other hand, both malicious insiders and external cyber‐attackers could deliberately disrupt CPSs using acquired knowledge of the system's security vulnerabilities and the dependencies between its system layers.53, 85. In this regard, we describe the roles of humans and their implications in CPSs in Section 3. A cyber-physical system (CPS) refers to the combination of computer-aided, software components with mechanical and electronic parts, which can be accessed via a data infrastructure, such as data centers where the Internet communicates. Finally, the cyber aspects are higher‐level information technology (IT) systems connected to the cyber‐physical aspects and, only indirectly, to the physical aspects. In other words, the cyber‐physical aspects are operational technology (OT) geographically and functionally located in proximity to the physical aspects. A series of more recent examples confirms this fact. In further work, we will integrate the CPS master diagram with the UFoI‐E concept, generating a method to perform a combined safety and security risk analysis and support responsible innovation in CPS applications. In December 2018, an accident involving an Amazon's automated robot punctured a bear repellent spray in a warehouse in New Jersey.87 After spreading through the warehouse ventilation system, workers became exposed and two dozen of them had to be hospitalized. In contrast to general‐purpose computers and industrial controllers, ESs are restricted by their smaller sizes, requiring high levels of design efficiency. and you may need to create a new Wiley Online Library account. The computer offers no assistance: human must take all decisions and actions. The connectivity of the cyber layer to the cyber‐physical allows malicious insiders to use HMIs to attempt disruptions of the cyber‐physical layer. Furthermore, the relations between levels of automation and human supervision are ambiguous in CPSs. Typical applications are condition monitoring, predictive maintenance, image processing and diagnosis. Neither this nuclear facility nor the Maroochy Water Services plant was composed exclusively of ESs and their system architectures were not completely autonomous. Fully automated control and AI: CPSs could operate in semi‐autonomous configurations and with traditional algorithms. Engineering of Cyber-Physical Systems: CPS opens a new opportunity to rethink principles of systems engineering, built on the foundation of CPS science and technology and able to support open cyber-physical systems. The focus of this paper is on Cyber-Physical Systems (CPSs), as one of the most promising transformative technological concept of such a context, thus considered by literature as the building blocks of future smart factories. In CPSs, safety is an emergent property that does not necessarily improve solely by enhancing the reliability of individual components or software.14 As a result, risk analysts working on multiple CPS applications require an understanding of the complex interactions and security vulnerabilities existing in general CPS features and their potential to influence safety. Other notorious cases for human safety are transportation systems. Theory and Applications, Security assurance levels : a vector approach to describing security requirements, Security for industrial communication systems, National Cyber Security Centre, National Crime Agency, The cyber threat to UK business: 2017–2018 Report. However, CPSs are still in their conceptualization phase. Outside this domain, we subdivide the environments interacting with the system into a cyber and a physical environment. These quantities can be measured by analog sensors or simply perceived by the human operators, who then decide which actions to take to close the feedback control loop in the physical layer. These deviations—ranging from unintended incidents to deliberate attacks—are sources of risk to the system at the cyber and cyber‐physical layers. Consequently, real‐time computations and communications are supplanting the human from the control functions, partially removing the human from the physical interface with the system. Cyber physical system (CPS) enables companies to keep high traceability and controllability in manufacturing for better quality and improved productivity. Researchers and practitioners are designing and prototyping autonomous vehicles (AVs) with higher levels of automation and connectivity.2 Similarly, the healthcare sector is developing novel medical applications to better support and treat patients, including autonomous implantable devices and system architectures for monitoring patients in hospitals or at home.3 Other relevant CPS applications include industrial control systems (ICSs) in manufacturing and process plants, robotics, control systems in critical infrastructures providing essential services to communities4 (eg, smart grids, water and wastewater systems), and autonomous military defense missiles, among others. Generalizing these examples to the context of CPSs, safety risks threaten human and assets within the system itself (eg, vehicle drivers, plant workers, patients wearing medical devices). Instead, many IoT system architectures develop mobile apps or cloud applications as final services,36, 37 using the integration of smart sensors, wireless networks, internet access, and cloud platforms with advanced data analytics. From this perspective, the CPS concept is a paradigm shift for the ESs community. Nevertheless, the overlapping CPS‐IoT field (also known as IoT‐based CPSs 34) incorporates both set of capabilities in these systems. Given that this CPS threshold of automation is general in scope but detailed in description, it is suited for extrapolation to other application‐based criteria used in different CPSs. Cyber-physical systems, which consist of physical systems tightly integrated and/or controlled by software, are ubiquitous in many safety critical domains, including automotive, avionics, railways, healthcare, atomic energy, power, and industrial automation. As specified by Sheridan,30 many systems allow for different levels of sharing and trading control between computers and humans. Some IoT applications provide smart actuator commands from real‐time sensor readings. The computer decides everything, acts autonomously, ignoring the human. Energy flows are transmissions of energy or matter required to achieve the functional goals of the system in the form of physical work. Cyber-physical systems combine digital and analog devices, interfaces, networks, computer sys- tems, and the like with the natural and man-made physical world. Other particular flows across these layers include the cases where humans edit the parameters of sensors through HMIs. His main research interest is the integration of the safety and security fields, enhancing risk science to support responsible innovation in cyber‐physical systems and critical infrastructures. This flexibility in automation allows the system to adapt and reduce the level of automation when it is required. Thus, these special control decisions require human decision‐making, while the real‐time control system directly executes the main functions in normal conditions. In some cases, sensors and the actuators are embedded into motes. Cloud platforms and cloud computing are also possibilities at this level. The relevance of these processes in security were evident after the WannaCry ransomware attack in 2017, which exploited a vulnerability in Windows computers that Microsoft had patched 2 months before. At this level, “decisions and actions are performed autonomously with human supervision. Using the CPS master diagram defined in this paper as a framework for risk analysis, practitioners from multiple disciplines can apply existing or new risk identification techniques to analyze different CPS applications. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. A review on the characteristics of cyber-physical systems for the future smart factories, interoperability, connectivity, communication, networking capability, modularity, autonomy, self-capabilities, decentralization, scalability, dynamic reconfigurability, adaptability. This property entails that the system as a whole is the entity that holds all relevant knowledge, whereas different individuals have partial views. In these cases, the real‐time communication network conveys the information flows from the sensors to higher‐level programmable controllers (eg, PLCs, DCS controllers, embedded computers). As outputs, actuators are responsible of transforming digital commands into energy flows influencing the physical layer. She has more than 50 publications peer‐reviewed papers, including around 20 papers in international journals. According to the National Science Foundation, “Cyber-physical systems (CPS) are engineered systems that are built from, and depend upon, the seamless integration of computation and physical… She has also been contributing to a high number of studies for industry companies. Unsafe manipulation of network (eg, plugging infected drives to a workstation, clicking phishing attack links) can lead to the propagation of viruses throughout the cyber layer with potential repercussions to the cyber‐physical layer. is a platform for academics to share research papers. The field of cybernetics established the foundations for engineered feedback control systems interacting with the physical world, even before the revolution in digital computation and network communications.6 Norbert Wiener opened the field of cybernetics in 1948, from applications in automatic weapon systems expanding to a wide field of technical systems and even to human behavior and neuroscience.41, Considering this perspective from the evolution in cybernetics, the notion of CPSs as strictly centered in ESs would be very restrictive. As an alternative, in further work we aim at providing a risk identification method for CPSs, conceptualizing the deviation of cyber processes as Uncontrolled Flows of Information (UFoI). In this sense, we define cyber processes as the uses of IT to control information flows as immediate goal (eg, obtain, store, compute, and transmit). He holds a master's degree in Technology and Socioeconomic Planning (cand.techn.soc.) The physical components control a set of physical dynamics, confining energy flows according to the system goals. Narrows the selection down to a few, OR, 5. These information flows are transmitted through real‐time communication networks. In this way, the communications do not require long travel distances that could represent a higher latency. This diagrammatic multi‐layered representation identifies the information and energy flows and their feedback loop interactions. For each question, we discuss the implications for safety and security risk analysis using recent historical incidents and describing the technologies and system architectures of several CPS applications. Accordingly, Parasuraman et al70 proposed a design framework to evaluate how the types and levels of automation have repercussions for human operators. As an input, sensors perceive physical quantities from the physical layer and transform them into digital packets. These new challenges demand system engineers and risk analysts to understand the security vulnerabilities existing in CPS features and their dependencies with physical processes. The term IoT was proposed by Kevin Ashton in 1999,37 initially stressing the rising capabilities of radio frequency identifiers (RFID) and wireless technologies. Conversely, high stress situations and non‐routine tasks with reduced time constraints raise the probability of human error. Then, improvements in aircraft and industrial process control led to the advent of distributed control systems (DCSs) in the 1970s, enabling remote control operations and a research interest on teleoperation.30, 44 The feedback control was no longer point‐to‐point. Particularly, people, assets, or natural environments located geographically near to the physical layer of the CPS (or describing physical dependencies with CPS functions) may experience losses due to hazardous events arising from within the CPS. Please comment about any uses you have made with Cyber Physical Systems. The computer becomes an automatic controller in systems “c” and “d,” closing partially or even completely the feedback loops. These two cases go in the opposite direction to the main loops of the system, evidencing the complexity in the dependencies in CPSs between their cyber‐physical and cyber layers. Particularly, he mentions reactive computations, concurrency, feedback control, real‐time computation, and safety‐critical applications. Lyngby, 2800, Denmark. In all these three examples, the CPS stakeholders are not responsible for maintaining and assuring the service continuity of these external systems. For this same reason, real‐time control systems (and not human operators) are usually in charge of these critical functions. Conversely, if the level ends with an OR, the next level imposes a new restrictive constraint. Even considering the increasing tendency to include ESs, wireless networks, and Internet access in DNCSs,31, 44, 46 these features do not exclude OT and wired local networks from the domain of CPSs because they provide the same essential function of integrating cyber and physical processes in control systems. Moreover, in the following subsection, we argue that DNCSs—as conceived in Ge et al.31—describe the key features of CPSs, considering the cooperative feedback control capabilities arising from the tight integration of cyber and physical processes. The concept of UFoI refines the Uncontrolled Flow of Energy (UFoE) model proposed in97 to the field of CPS, considering that cyber, cyber‐physical, and physical processes are interdependent and interact with their environments. Recent incidents confirm the rising importance of cybersecurity to ensure safety in diverse CPS applications. Particularly, this explicit relationship between a threshold of automation and CPSs as a class of systems serves two relevant purposes. Nevertheless, this state of automation can be dynamic, where operators can deliberately take manual control in special cases. This paper is organized as follows. The transition from the cyber‐physical to the cyber layer can materialize in two different ways. In This presentation, a CPS is defined, its characteristics and benefits are listed and its impacts on products are discussed. Analogously, we consider as accessory (ie, not key) features the fully automatic control capabilities and possible developments in AI‐based control in CPSs. Indeed, ESs could be used solely on sensor devices, providing data to human operators or to application platforms as a service. Traditionally in industrial applications and safety‐related systems, these cyber‐physical processes have been divided in basic process control system (BPCS) and safety instrumented system (SIS), with independent functions and isolated architectures.95 In contrast, the cyber‐physical layer in CPSs increasingly interconnect and integrate the SIS with the BPCS and higher‐level computer systems,96 exposing the system to new safety issues. Mary Ann Lundteigen has been a professor in Department of Mechanical and Industrial Engineering since 2011, with a period with DNV‐GL as Principle Engineer from 2012–2013. Small in code size: considering limited memory size in embedded microcontrollers. Several factors compromise the intended human‐machine interactions. By conducting standard IT intrusion mechanisms, the attackers penetrated into the network and targeted the connected safety instrumented system (SIS).59 Even though the SIS operated with a proprietary network protocol, enough knowledge of the proprietary system and its connections to general IT networks enable this type of cyber‐attacks to target the SIS and induce physical harm.60. A widespread definition of a CPS is the “integration of computation and physical processes.”23 Nevertheless, the broadness of this and other definitions may obscure the identification of the key features of CPSs, that is, the common characteristics that proof the utility for grouping this wide set of systems into a common class. Note that the physical layer of the system and the physical environment exchange energy flows in both directions, evidencing the region where safety hazards could potentially develop across these interfaces. These flows include the interactions between operators and technologies through HMIs. For instance, the NSF defines CPSs as “engineered systems that are built from, and depend upon, the seamless integration of computation and physical components.”9 In similar terms, Rajkumar et al.1 characterized CPSs as “physical and engineered systems whose operations are monitored, controlled, coordinated, and integrated by a computing and communication core.” In general, these and other definitions stress the integration of computers to control physical components. How can system designers and risk analysts describe the features of CPSs in a comprehensive representation for safety and security analysis? Other societies have developed their own criteria for levels of automation in their particular sectors, such as railway,72 ships,73 aircraft,74 unmanned aerial vehicles (UAVs),75 among others. 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