Characteristics Of Cyber-physical Systems Research Articles

A Modeling and Verification Method of Cyber-Physical Systems Based on AADL and Process Algebra

Cyber-Physical Systems (CPS) are the next generation of intelligent systems that integrate information control devices with physical resources. With increasingly close connections between CPS components and frequent interactions, potential defects grow exponentially, rendering the operating environment of CPS unreliable. Therefore, research on methods and theories to ensure the correctness, safety and reliability of CPS is not only an important research topic but also an inevitable challenge. In this paper, we propose a CPS modeling and verification method based on Architecture Analysis & Design Language (AADL) and process algebra to address this challenge. Due to the continuous, time-constrained, stochastic, uncertain and concurrent characteristics of CPS, this paper considers both flexibility and rigor in the modeling process. We first extend the ability of AADL to describe the multiple characteristics of CPS and propose Hybrid Probability-AADL (HP-AADL). Second, this paper introduces conditional execution, conditional interruption and probability operators into Temporal Calculus of Communication Systems (TCCS) and designs a new formal modeling language Hybrid Probability-Temporal Calculus of Communication Systems (HP-TCCS). However, HP-AADL is a semi-formal modeling language that cannot be directly used for formal verification, it cannot strictly guarantee the quality of the established CPS models, including its functional correctness and safety. Therefore, this paper proposes transformation rules from HP-AADL to HP-TCCS, which enables model checking of CPS models described in HP-AADL within HP-TCCS. Additionally, this paper designs a new formal specification language HPAT-Spatial Temporal Logic (HPAT-STL) based on Probabilistic Computation Tree Logic (PCTL) and Spatial Logic, which characterizes the temporal, probabilistic and spatial properties of CPS model. To achieve formal verification of HP-TCCS model and HPAT-STL formulas, this paper proposes a model checking algorithm HPAT-Model Checking Algorithm (HPAT-MCA). Finally, we discuss a typical CPS example to demonstrate the effectiveness of our proposed method in ensuring correct, safe and reliable CPS.

Analysis of safety and security challenges and opportunities related to cyber-physical systems

A cyber-physical system (CPS) is an interconnected physical system that can be monitored, controlled, and operated remotely. A systems-based analysis of CPS is critical for enhancing operational safety and security. Such analysis is particularly important in light of the evolving Fourth Industrial Revolution (Industry 4.0) which is largely driven by CPS, Internet of Things (IoT), algorithmic systems, automation, and smart manufacturing. As a result of industries’ and societies’ growing dependence on CPSs, their safe and secure applications need to be scrutinized to avoid any threats or harm to processes and human lives. In order to achieve this target, the current work analyzes the literature to investigate challenges and opportunities present in the CPSs. The analysis attempts to answer the following Research Questions (RQs): (RQ1) What are the prominent trends in the field of safety and security of CPSs? (RQ2) What are the opportunities in Industry 4.0 technologies related to safety? (RQ3) What characteristics of CPSs are likely to cause safety and security issues? (RQ4) What are the emerging safety and security issues introduced by CPSs? (RQ5) How were these issues addressed in the literature? CPSs can address some traditional safety issues due to characteristics like high efficiency and control. However, a CPS is challenged by heterogeneity, dependencies, complexity, unattended nature, increased machine intelligence, autonomous reconfiguration, and uncertainties. Safety and security challenges include opaque system failure, complex socio-technical system, human-machine interface, cyber-physical attacks, unsecured remote configuration, lack of standards, and resilience. The paper is structured under the following key headings: bibliometric results, opportunities from Industry 4.0 technologies, issues introduced by Industry 4.0 technologies, literature proposed solutions, and research challenges. Based on the assessment of about 900 relevant publications extracted from two databases (Web of Science (WoS) Core Collection and Engineering village (EV)), the documents were categorized into eight major divisions: (i) Safety Opportunities, (ii) Hazardous Characteristics, (iii) Fault Occurrence, (iv) Cyber-physical attacks, (v) Human factors, (vi) occupational Health and safety, (vii) standards, and (viii) Reliability and resiliency. Proactive strategies were classified under four options: identification, evaluation, prevention, and management. The paper also raises some research needs and unanswered questions that require further analysis to address how security and safety mechanisms can introduce more complexity in the system that can lead to new risks. The paper concludes by emphasizing digital process safety as part of the engineering curriculum to address the process industry's need for digital solutions and to make process safety learning a conscious choice.

Model-based engineering for designing cyber-physical systems from product specifications

Cyber-physical systems (CPS) are composed of independent and cooperative elements. Rapid adaptation to disturbances is an essential characteristic of CPS. One of the challenges in designing CPS is considering these specificities. Model-Based Engineering is a method for reducing complexity in system design. This paper presents a methodology for designing CPS and its control system using System Modeling Language (SysML) diagrams and IEC 61499 standard. The product's specifications are the starting point; the methodology focuses on what is produced before determining how to make it. The real-time control system is designed from high-level knowledge and tested software components on the plug and produce principle. Task-based structural analysis ensures the elements' synchronization to determine the system's general behavior.

Mithra: Anomaly Detection as an Oracle for Cyberphysical Systems

Testing plays an essential role in ensuring the safety and quality of cyberphysical systems (CPSs). One of the main challenges in automated and software-in-the-loop simulation testing of CPSs is defining effective oracles that can check that a given system conforms to expectations of desired behavior. Manually specifying such oracles can be tedious, complex, and error-prone, and so techniques for automatically learning oracles are attractive. Characteristics of CPSs, such as limited or no access to source code, behavior that is non-deterministic and sensitive to noise, and that the system may respond differently to input based on its context introduce considerable challenges for automated oracle learning. We present Mithra, a novel, unsupervised oracle learning technique for CPSs that operates on existing telemetry data. It uses a three-step multivariate time series clustering to discover the set of unique, correct behaviors for a CPS, which it uses to construct robust oracles. We instantiate our proposed technique for ArduPilot, a popular, open-source autopilot software. On a set of 24 bugs, we show that Mithra effectively identifies buggy executions with few false positives and outperforms AR-SI, a state-of-the-art CPS oracle learning technique. We demonstrate Mithra’s wider applicability by applying it to an autonomous racer built for the Robot Operating System.

Modeling and vulnerability assessment of cyber physical system considering coupling characteristics

The smart grid is a typical cyber physical system (CPS). Communication networks and power networks have the structural coupling and functional coupling characteristics, which may induce cyber-physical coupling failures. To reveal the vulnerability characteristics of CPS, this paper proposes the CPS interdependence model and analyzes the vulnerability of CPS. Firstly, considering structural coupling of the power and communication system, structural characteristics and networking constraints of fiber optic communication networks, the communication network topology generation model is proposed. Then, based on the generated communication network, the CPS interdependence model is built, which describes the structural and functional coupling between power and communication network. Finally, based on the fault chain theory, the CPS cascading failure analysis model is proposed to assess the vulnerability. In the case study, IEEE 118-bus system is taken as an example to generate communication network, and the validity of the communication network topology model is verified by comparing structural features with actual networks. The influence of the proportion of composite lines (optical fiber composite overhead ground wire, OPGW), and information failure on vulnerability of CPS are analyzed.

Automated in situ consolidation process for pre-impregnated carbon fibers: a cyber phisycal approach

The concept known as the fourth industrial revolution (Industry 4.0) has developed a wide field of study, such as the Internet of Things (IoT), Cyber-Physical Systems (CPS) and Information and Communication Technology (ICT), with the objective to achieve enhancing the processes performance of automated systems. This work focuses on the field of CPS for an in situ consolidation machine, which handles pre-impregnated, in this case unidirectional carbon fiber tapes with polyamide 6, in order to create composite laminates. The physical model involves an unwinding system that feeds the tape into a turning table through a pressing mechanism, which has a radiation heater before and refrigeration after the presser to guarantee the composite temperature. The objective is to model and simulate the heating process before, during and after the pressing mechanism to feed an optimization algorithm in order to calculate the optimal working parameters such as heaters power, heater positioning and process speed taking into account the temperatures of the tape, to avoid overheating and to improve process time. The results are processed, so that they can send and receive data constantly, to an optimization system to alter parameters, without making programing code changes and avoiding the need to stop the consolidation. The CPS can handle different classes of pre-impregnated composites, by learning during the consolidation process, in order to improve the overall result, without the need of fully or partially reprograming the code, which a main characteristic of CPS.

ATMChain: Blockchain-Based Security Framework for Cyber-Physics System in Air Traffic Management

The air traffic management (ATM) system is an intelligent system that integrates the ground computer network, the airborne network, and the space satellite (communication and navigation) network. It has remarkable characteristics of cyber-physical system (CPS). The development of ATM system is inseparable from the application of new technologies. This paper proposes a security framework based on blockchain for CPS in the ATM system. Through the research on the characteristics of blockchain and CPS, this paper analyzes the necessity of integrating them into the research of the ATM system, demonstrates the feasibility of combining them, and then constructs the ATMChain framework mechanism to realize the in-depth integration of blockchain and CPS in ATM. On this basis, this paper gives the overall design architecture and implementation steps of the scheme. In addition, this paper also makes a series of analysis and demonstration from the perspective of scheme security. The research scheme will help to improve the security, reliability, and scalability of ATM services and provide a new reference for establishing a more security and efficient ATM system.

Energy Aware Secure Cyber-Physical Systems with Clustered Wireless Sensor Networks

Recently, cyber physical system (CPS) has gained significant attention which mainly depends upon an effective collaboration with computation and physical components. The greatly interrelated and united characteristics of CPS resulting in the development of cyber physical energy systems (CPES). At the same time, the rising ubiquity of wireless sensor networks (WSN) in several application areas makes it a vital part of the design of CPES. Since security and energy efficiency are the major challenging issues in CPES, this study offers an energy aware secure cyber physical systems with clustered wireless sensor networks using metaheuristic algorithms (EASCPS-MA). The presented EASCPS-MA technique intends to attain lower energy utilization via clustering and security using intrusion detection. The EASCPS-MA technique encompasses two main stages namely improved fruit fly optimization algorithm (IFFOA) based clustering and optimal deep stacked autoencoder (OSAE) based intrusion detection. Besides, the optimal selection of stacked autoencoder (SAE) parameters takes place using root mean square propagation (RMSProp) model. The extensive performance validation of the EASCPS-MA technique takes place and the results are inspected under varying aspects. The simulation results reported the improved effectiveness of the EASCPS-MA technique over other recent approaches interms of several measures.

Engineering cyber‐physical systems through performance‐based modelling and analysis: A case study experience report

AbstractThe process of engineering cyber‐physical systems (CPS) is inevitably challenging because of the intrinsic problem of merging the specification of different ensembles that indicate hardware, software, and physical aspects of such systems. This intrinsic complexity is exacerbated when modelling and analysing the performance characteristics of CPS since multiple models need to coexist in order to get meaningful performance indicators. In this paper, we present a case study, a delivery robots system, whose experience is exploited towards building a guided process for engineering CPS through performance‐based modelling and analysis. Model‐based performance results are provided while analysing different design alternatives, thus to support architects in the process of better understanding the performance characteristics of CPS under development.

Emerging Education Challenges for Resilient Cyber Physical Systems

AbstractEngineering resilient cyber physical systems (CPS) is viewed as a systems engineering (SE) challenge. The research and education programs in computer and software security and resilience were advanced through the 1990's with many formal approaches to system reliability, security, dependability, and safety. Since that time, the internet and the information security needs in information technology (IT) systems has had a large education focus. Meanwhile, the scale and complexity of today's critical computing systems used in engineering domains has increased immensely. There has not been a related increased focus on research, knowledge, and education specifically addressing dependable and secure computing in domains such as infrastructure, industrial control, defense, and emerging commercial autonomous systems and the Internet of Things (IoT). While security education in the U.S. has greatly expanded in the domain of IT systems and related computer science and engineering fields, there exists a lack of engineering education programs and opportunities for engineering graduates to gain knowledge and skills related to design of secure, safe, and dependable CPS, what we call resilient CPS. There is also a lack of investment in laboratory facilities that can simulate large scale CPS, which are costlier to develop than IT related facilities. Formal research or studies in CPS and resilient computing related curricula are also difficult to find, although the domain is well researched. This paper discusses the primary foundations and characteristics of resilient CPS as a step toward a general taxonomy, the emerging needs and gaps in engineering education related to these systems, and the knowledge areas and bodies of knowledge that are already established or need to be developed in the education system. The goal is to bring broad attention in the systems engineering community to these needs.

CPS data streams analytics based on machine learning for Cloud and Fog Computing: A survey

Cloud and Fog computing has emerged as a promising paradigm for the Internet of things (IoT) and cyber–physical systems (CPS). One characteristic of CPS is the reciprocal feedback loops between physical processes and cyber elements (computation, software and networking), which implies that data stream analytics is one of the core components of CPS. The reasons for this are: (i) it extracts the insights and the knowledge from the data streams generated by various sensors and other monitoring components embedded in the physical systems; (ii) it supports informed decision making; (iii) it enables feedback from the physical processes to the cyber counterparts; (iv) it eventually facilitates the integration of cyber and physical systems. There have been many successful applications of data streams analytics, powered by machine learning techniques, to CPS systems. Thus, it is necessary to have a survey on the particularities of the application of machine learning techniques to the CPS domain. In particular, we explore how machine learning methods should be deployed and integrated in Cloud and Fog architectures for better fulfilment of the requirements of mission criticality and time criticality arising in CPS domains. To the best of our knowledge, this paper is the first to systematically study machine learning techniques for CPS data stream analytics from various perspectives, especially from a perspective that leads to the discussion and guidance of how the CPS machine learning methods should be deployed in a Cloud and Fog architecture.

Smart Logistics Path for Cyber-Physical Systems With Internet of Things

Logistics system is developing in the direction of intelligence. The realization of smart logistics is inseparable from the coordination of logistics operation systems and information systems. Cyber-Physical Systems (CPS) are a new intelligent complex system that integrates deep computing, control, and communication technologies, one of its main application areas is the logistics and transportation industry. Nowadays, logistics industry is developing rapidly. Based on the existing logistics system and combining the characteristics of CPS, this paper proposes a path decision method based on intelligent algorithm. Based on the CPS logistics path decision model, the Internet of Things technology and cloud platform data storage technology are introduced into the interconnection design and data processing of the equipment layer. The application effects of ant colony algorithm, simulated annealing algorithm, and genetic algorithm in logistics path optimization are analyzed in detail. By comparing the shortest transport distance and convergence speed under the three algorithm decisions, it is concluded that the ant colony algorithm has the best path optimization effect in solving the logistics path decision.

Linked Block-based Multiversion B-Tree index for PCM-based embedded databases

In this paper, by exploring the application characteristics of cyber-physical systems (CPS) and the performance characteristics of PCM, we propose a new B-tree index structure, called Linked Block-based Multi-Version B-Tree (LBMVBT), for indexing multi-version data in an embedded multi-version database for CPS. In LBMVBT, to reduce the number of writes to PCM in maintaining the index and improve the efficiency in serving version-range queries, we introduce the block-based scheme for indexing in which multiple versions of a data item are grouped into a version block to be indexed by a single entry in the multi-version index. To reduce the index re-organization cost (i.e., number of writes to PCM) due to node overflow and underflow, we add external entries in each index leaf node so that a node re-organization can be done by only updating pointers without copying the index entries of the re-organized leaf nodes to the new node. Analytic studies have been performed on LBMVBT and a series of experiments has been conducted to evaluate the efficacy of LBMVBT. The experimental results show that LBMVBT can effectively reduce the number of writes to the index and achieve a good overall performance on serving update transactions while version-range queries can be served with smaller number of reads to the index compared with MVBT.

Current status and advancement of cyber-physical systems in manufacturing

This paper presents the current status and the latest advancement of cyber-physical systems (CPS) in manufacturing. In order to understand CPS and its future potential in manufacturing, definitions and characteristics of CPS are explained and compared with cloud manufacturing concept. Research and applications are outlined to highlight the latest advancement in the field. CPS shows great promise in factories of the future in the areas of future trends as identified at the end of this paper.

Measuring a Composition Event Representation Model Based on Multi-Tuple for Cyber-Physical Systems

Representation model of composition event is a very important issue in the study of composition event. Aiming to solve the problem of no well reflecting the spatial-temporal characteristic of CPS (Cyber-Physical Systems) in current composition even models, a representation model of composition event based on multi-tuple is proposed for CPS in this paper. The contribution of the paper lies that we use five tuples: object, time, space, event and property, to represent a composition event of CPS, which not only can more comprehensively reflect the spatial-temporal characteristic of CPS event, but also can reflect the some dynamic change features of external environment. The simulation results show that our proposed scheme has several advantages in reducing event average error rate compared with some general event model methods.

A new practice-driven approach to develop software in a cyber-physical system environment

Cyber-physical system (CPS) is an emerging area, which cannot work efficiently without proper software handling of the data and business logic. Software and middleware is the soul of the CPS. The software development of CPS is a critical issue because of its complicity in a large scale realistic system. Furthermore, object-oriented approach (OOA) is often used to develop CPS software, which needs some improvements according to the characteristics of CPS. To develop software in a CPS environment, a new systematic approach is proposed in this paper. It comes from practice, and has been evolved from software companies. It consists of (A) Requirement analysis in event-oriented way, (B) architecture design in data-oriented way, (C) detailed design and coding in object-oriented way and (D) testing in event-oriented way. It is a new approach based on OOA; the difference when compared with OOA is that the proposed approach has different emphases and measures in every stage. It is more accord with the characteristics of event-driven CPS. In CPS software development, one should focus on the events more than the functions or objects. A case study of a smart home system is designed to reveal the effectiveness of the approach. It shows that the approach is also easy to be operated in the practice owing to some simplifications. The running result illustrates the validity of this approach.

Assisting the Design of Sensor and Information Fusion Systems

Abstract The increased deployment of information technology for information processing, extensive networking, and system/environment monitoring using sensor and information fusion systems are essential characteristics of cyber-physical systems. They allow an autonomous recognition and evaluation of the system's status leading to autonomous reactions improving or maintaining the status to operate adaptively, robustly, anticipatory, and user-friendly. Assisting the operator in handling such complex systems is rather important and requires self-configuration, self-diagnosis, and self-optimization capabilities. In this paper, a new assisted design methodology for sensor and information fusion systems is proposed. It is based on an innovative system architecture consisting of the information fusion system itself, intelligent adaptable sensors, and the communication architecture of the “Intelligent Technical Systems OstWestfalenLippe” (it's OWL) Leading-Edge Cluster project “Intelligent Networking” providing an intelligent network for self-configuration and the required real-time data exchange.

Compound Tension Control of an Optical-Fiber Coil System: A Cyber-Physical System View

The full-automatic optical-fiber coil winding equipment is a complex electromechanical system which contains signal acquisition, data processing, communications, and motor control. In the complex electromechanical system, the subsystems rely on wired or wireless network technology to complete the real-time perception, coordinate, accurate, and dynamitic control, and information exchange services. The paper points to the full-automatic optical-fiber coil winding equipment with the characteristics of cyber-physical system to research its numerical design. We present a novel compound tension control system based on the experimental platform dSPACE to achieve semiphysical simulation of compound tension control system and examine the functions of control system.

Fusion Framework of Urban Traffic Control and Route Guidance Based on Cyber-physical System Theory

To avoid traffic congestion, improve transport efficiency, and meet the requirements of users and traffic flow equilibri­ urn, the fusion framework of urban traffic control and route guidance was studied. The characteristics of an urban traffic control and route guidance system and a cyber-physical system (CPS) were analyzed, and the relationship between such systems was examined. The technical requirements of the application of CPS theory to an urban traffic control and route guidance system were discussed. Based on the components of a dynamic urban traffic flow guidance system (UTFGS) and urban traffic control system ( UTCS), considering the man-machine system characteristics of CPS, and in the light of relevance, conflict, and solution method of both systems, a fusion framework for urban traffic control and route guidance based on the CPS was proposed. This framework involves computation, communication, control, and physical components that facilitate the enhancement of the fusion degree of the UTFGS and the UTCS. The proposed framework focuses on the technical analysis of the feasibility of the depth fu­ sion of both systems and provides a theoretical basis for the implementation of urban traffic control and route guidance fusion in intelligent traffic systems.

A modified feedback controlled car-following model considering the comprehensive information of the nearest-neighbor leading car

Congestion control is a process to achieve optimal decision-making and effective control of vehicles through the interaction of vehicular perception and control, it shows the typical characteristic of cyber physical systems. Based on the pioneer work of Konishi et al., we present a new feedback control scheme to suppress traffic jam in the coupled map car-following model under open boundary condition, which considers the effect of safe headway and optimal velocity difference on the traffic system from the perspective of tight conjoining between the transportation cyber system and the transportation physical system. According to the control theory, the condition under which traffic jam can be suppressed is analyzed. Both theoretical analyses and simulation results show that the suppression performance of our scheme is better than those of the previous schemes, although all the schemes can suppress traffic jam.