Design Of Cyber-physical Systems Research Articles

A model-based approach for self-adaptive security in CPS: Application to smart grids

Security risk assessment is an important challenge in the design of Cyber Physical Systems (CPS). Even more importantly, the intrinsically dynamical nature of these systems, due to changes in their environment, as well as evolutions in their infrastructures, makes them self-adaptive systems, where security aspects have to be considered in terms of management of detections and reactions for self-protection. In this work, we propose an approach to autonomously mitigate the threats in each reconfiguration at application or infrastructure levels of CPS. We propose and implement a framework for self-adaptive security: software architecture, design method, and integration with model-based decision. We use Attack-Defense Trees for modeling threats, and our approach involves security risk assessment, taking into account its balancing and coordination with quality-of-service aspects. We formulate and formalize the on-line decision problem to be solved at each cycle of the self-adaptation control loop in terms of Constraint Programming (CP) modeling and resolution. The CP model implements a set of constraints that allow to specify secure configurations, evaluated regarding their impact on system performance to pinpoint the most relevant one portraying a good balance between the security and quality of service. We perform validation of our approach with its application to Smart Grids, more particularly to an industrial case study from RTE (the French Energy Transmission company).

The Impact of Network Design Interventions on the Security of Interdependent Systems

We study the problem of defending a Cyber-Physical System (CPS) consisting of interdependent components with heterogeneous sensitivity to investments. In addition to the optimal allocation of limited security resources, we analyze the impact of an orthogonal set of defense strategies in the form of network design interventions in the CPS to protect it against the attacker. We first propose an algorithm to simplify the CPS attack graph to an equivalent form which reduces the computational requirements for characterizing the defender's optimal security investments. We then evaluate four types of design interventions in the network in the form of adding nodes in the attack graph, interpreted as introducing additional safeguards, introducing structural redundancies, introducing functional redundancies, and introducing new functionalities. We identify scenarios in which interventions that strengthen internal components of the CPS may be more beneficial than traditional approaches such as perimeter defense. We showcase our proposed approach in two practical use cases: a remote attack on an industrial CPS and a remote attack on an automotive system. We highlight how our results closely match recommendations made by security organizations and discuss the implications of our findings for CPS design.

Neurotechnologies Applied to Society's Perception of Cyber-Physical Systems (CPS) in Smart Cities

This study aims to quantify the perception of value and acceptance by citizens of the use of cyber-physical systems (CPS) in transportation systems and smart cities using neurotechnologies. The work has been developed in the main cities of the following Latin American countries: Spain, Ecuador, Colombia, and Argentina. Targeting urban, public transport-using graduates, it assesses CPS in smart cities and user experiences. Triangulating qualitative research and neurotechnology, the study extends the taxonomy of emotional domains. The results indicate that users do not always assign equivalent importance to what they truly feel, and it is noteworthy that the most important factor, both quantitatively and emotionally, is the application of CPS to improve efficiency in public transportation. The implications of these analyses are discussed in the final part of the article with the aim of providing recommendations to policymakers on the key aspects to be considered in the design and development of CPS for use in smart cities.

Distributed Interval Observers with Switching Topology Design for Cyber-Physical Systems

In this paper, the distributed interval estimation problem for networked Cyber-Physical systems suffering from both disturbances and noise is investigated. In the distributed interval observers, there are some connected interval observers built for the corresponding subsystems. Then, due to the communication burden in Cyber-Physical systems, we consider the case where the communication among distributed interval observers is switching topology. A novel approach that combines L∞ methodology with reachable set analysis is proposed to design distributed interval observers. Finally, the performance of the proposed distributed interval observers with switching topology is verified through a simulation example.

Design and Validation of Cyber-Physical Systems Through Co-Simulation: The Voronoi Tessellation Use Case

Design and Validation of Cyber-Physical Systems Through Co-Simulation: The Voronoi Tessellation Use Case

Learning Secure Control Design for Cyber-Physical Systems Under False Data Injection Attacks

Learning Secure Control Design for Cyber-Physical Systems Under False Data Injection Attacks

Design and self-diagnostics of cyberphysical control devices on SOC platform

The subject of research in this article is models, methods, and procedures for designing and self-diagnosing automated models of logic control devices implemented in SoCs. The object of work is the procedures for automated design and diagnosis of digital devices on the SoC technology platform. The aim of the study is to develop models and procedures for designing and self-testing in the cycle of automated design of automatic logic control systems on the SoC technology platform, which will significantly increase the reliability of their operation. The article solves the following tasks: consideration of the procedures for interacting the processor core with programmable logic as part of the SoC; improvement of the procedures for designing and testing software and hardware systems based on SoC; further development of procedures for automated design, verification, and diagnosis of cyber-physical logic control systems using programming languages and hardware description languages; implementation of the procedure for hardware self-testing of control automata on the SoC technology platform. The following methods are implemented: synthesis of control automata based on graph models, implementation of control automata models in the C programming language using an automata template, diagnostic experiment by traversing the automata transition graph. Results achieved. Based on the analysis of the procedures for the interaction of the processor core and programmable logic on the selected SoC platform, a model of a cyber-physical logic control system was designed. The practical implementation was carried out on the basis of the Vivado/Vitis/Vitis HLS CAD toolkit. The method of hardware self-testing of control automata on the technological platform of SoC ZYNQ-7000 was implemented. Conclusions. The article analyzes the principles of designing embedded cyber-physical systems implemented in system-on-chip. The principles of building verification systems and embedded self-diagnostics of system-on-chip systems containing software and hardware are considered. The developed methods are tested on a model of a traffic light logic control device on the SoC FPGA platform of the ZYNQ-7000 family by Xilinx. The Moore's control automaton is implemented in the PL block in the C programming language, and the operational automaton is implemented in the PS block. During the organization of the self-diagnosis process, a non-destructive diagnostic experiment was performed by traversing all arcs of the transition graph, starting from the initial vertex. In this case, the tester was an operational automaton, the reference logic and time values of which were stored in the memory of the PS unit. Visual observation of the diagnostic experiment was carried out using the LED panel of the ZedBoard board.

A component-based design approach for energy flexibility in cyber-physical manufacturing systems

AbstractEnergy flexibility of manufacturing systems helps to meet sustainable manufacturing requirements and is getting significant importance with rising energy prices and noticeable climate changes. Considering the need to proactively enable energy flexibility in modern manufacturing systems, this work presents a component-based design approach that aims to embed energy flexibility in the design of cyber-physical production systems. To this end, energy management using Industry 4.0 technologies (e.g., Internet of Things and Cyber-physical Systems) is compared to the literature on energy flexibility in order to evaluate to what extent the energy flexibility practice takes advantage of Industry 4.0 technologies. Another dimension is the coverage of the life cycle of the manufacturing system which guarantees its sustainable design and the ability to achieve energy flexibility by configuring the energy consumption behaviour. A data-based design approach of the energy-flexible components is proposed in the spirit of the Reference Architectural Model Industrie 4.0 (RAMI 4.0), and then it is exemplified using an electric drive (as a component) in order to show the practical applicability of the approach. The energy consumption behaviour of the component is modelled using machine learning techniques. The digital twin of the studied component is developed using Visual Components virtual engineering environment, then its energy consumption behaviour is included in the model allowing the system integrator/decision-maker to configure the component based on the energy availability/price. Finally, external services in terms of an optimisation module and a deep learning module are connected to the digital twin.

Modeling more software performance antipatterns in cyber-physical systems

AbstractThe design of cyber-physical systems (CPS) is challenging due to the heterogeneity of software and hardware components that operate in uncertain environments (e.g., fluctuating workloads), hence they are prone to performance issues. Software performance antipatterns could be a key means to tackle this challenge since they recognize design problems that may lead to unacceptable system performance. This manuscript focuses on modeling and analyzing a variegate set of software performance antipatterns with the goal of quantifying their performance impact on CPS. Starting from the specification of eight software performance antipatterns, we build a baseline queuing network performance model that is properly extended to account for the corresponding bad practices. The approach is applied to a CPS consisting of a network of sensors and experimental results show that performance degradation can be traced back to software performance antipatterns. Sensitivity analysis investigates the peculiar characteristics of antipatterns, such as the frequency of checking the status of resources, that provides quantitative information to software designers to help them identify potential performance problems and their root causes. Quantifying the performance impact of antipatterns on CPS paves the way for future work enabling the automated refactoring of systems to remove these bad practices.

Cyber-WISE: A Cyber-Physical Deep Wireless Indoor Positioning System and Digital Twin Approach.

In recent decades, there have been significant research efforts focusing on wireless indoor localization systems, with fingerprinting techniques based on received signal strength leading the way. The majority of the suggested approaches require challenging and laborious Wi-Fi site surveys to construct a radio map, which is then utilized to match radio signatures with particular locations. In this paper, a novel next-generation cyber-physical wireless indoor positioning system is presented that addresses the challenges of fingerprinting techniques associated with data collection. The proposed approach not only facilitates an interactive digital representation that fosters informed decision-making through a digital twin interface but also ensures adaptability to new scenarios, scalability, and suitability for large environments and evolving conditions during the process of constructing the radio map. Additionally, it reduces the labor cost and laborious data collection process while helping to increase the efficiency of fingerprint-based positioning methods through accurate ground-truth data collection. This is also convenient for working in remote environments to improve human safety in locations where human access is limited or hazardous and to address issues related to radio map obsolescence. The feasibility of the cyber-physical system design is successfully verified and evaluated with real-world experiments in which a ground robot is utilized to obtain a radio map autonomously in real-time in a challenging environment through an informed decision process. With the proposed setup, the results demonstrate the success of RSSI-based indoor positioning using deep learning models, including MLP, LSTM Model 1, and LSTM Model 2, achieving an average localization error of ≤2.16 m in individual areas. Specifically, LSTM Model 2 achieves an average localization error as low as 1.55 m and 1.97 m with 83.33% and 81.05% of the errors within 2 m for individual and combined areas, respectively. These outcomes demonstrate that the proposed cyber-physical wireless indoor positioning approach, which is based on the application of dynamic Wi-Fi RSS surveying through human feedback using autonomous mobile robots, effectively leverages the precision of deep learning models, resulting in localization performance comparable to the literature. Furthermore, they highlight its potential for suitability for deployment in real-world scenarios and practical applicability.

AIoTML: A Unified Modeling Language for AIoT-Based Cyber–Physical Systems

Due to deeply intertwined physical and hardware/software components together with increasing number of interconnected heterogeneous devices powered by Artificial Intelligence (AI) techniques, the design complexity of Cyber-Physical Systems (CPSs) becomes skyrocketing. Model-Driven Engineering (MDE) methods have been proven to be effective in increasing the productivity of CPS design. However, there is still a lack of MDE approaches that enable design space exploration as well as the code generation for the design of AI IoT (AIoT)-based CPSs. To mitigate the situation, this paper presents a unified modeling language named AIoTML for AIoT-based CPSs, which enables the construction of AI-based components across different modeling levels for the purposes of intelligent sensing and control. By extending the constructs of state-of-the-art Domain-Specific Language (DSL) ThingML, AIoTML can seamlessly unify the modeling of both autonomous executions of AIoT devices and their surrounding physical environment, which facilitates both platform-independent simulation and control optimization for platform-specific CPSs. The compiler developed for AIoTML provides a family of code generators to support the construction of digital twins on various heterogeneous target AIoT platforms. Comprehensive evaluations on two complex real-world designs demonstrate the effectiveness of our AIoTML approach in fast development of AIoT-based CPSs with high control quality.

Unified Graphical Co-modelling, Analysis and Verification of Cyber-physical Systems by Combining AADL and Simulink/Stateflow

The design of safety-critical cyber-physical systems (CPSs) involve several dimensions, including physics, hardware rchitecture and software functionality. It is desirable to design CPSs by taking these issues into account uniformly and yet, few existing design workflows support this aim. For instance, AADL is an architecturecentric modelling formalism for CPSs, which focuses on modelling architecture and prototyping real-time hardware platforms, but it delegates physical and software behavioral models to so-called annexes. By contrast, Simulink/Stateflow (S/S) focuses on modelling interacting physical and software behaviors, but does not render the non-functional characteristics of their hardware platforms. To address this issue, in [1], we proposed the combination of AADL and S/S, called AADL S/S, to comodel CPSs and presented a method to uniformly analyse and verify them. AADL S/S provides a unified graphical co-modelling environment for CPS design and supports simulation through C code generation. Also, [1] presented a formal semantics of AADL S/S by translation to Hybrid Communicating Sequential Processes (HCSP), yielding a deductive verification framework of the combined models using Hybrid Hoare Logic (HHL). Additionally, [1] proved the correctness of the translation of AADL S/S to HCSP.

Systematic Reliability Optimization (ASRO)

Reliability optimization is a critical aspect of modern engineering systems and products, particularly with the growing complexity and interconnectedness of systems. This paper delves into the significance of reliability optimization and the techniques employed to achieve it. It highlights the benefits of optimizing reliability, including reduced costs, enhanced customer retention, and a competitive advantage. The paper discusses the challenges of balancing performance, cost, and reliability, especially in real-world systems with intricate nonlinear interactions between subcomponents. It introduces various reliability optimization techniques, including redundancy analysis, physics-based models, accelerated testing, and data-driven methods. The paper emphasizes the potential of advanced sensing and AI-based methods for reliability optimization. It highlights the importance of AI in optimizing the design and management of complex cyber-physical systems (CPS), where failures can have severe economic and safety consequences. The paper also discusses the empirical review of over 50 studies since 2016, which provides insights into the effectiveness of various optimization approaches across industry verticals. In conclusion, reliability optimization is crucial for the development and operation of modern engineering systems and products. Advanced sensing and AI-based methods offer promising solutions for optimizing reliability in complex systems, particularly CPS. By systematically optimizing reliability, companies can reap significant benefits and ensure the successful operation of their products and services.

Composite fault reconstruction and fault-tolerant control design for cyber-physical systems: An interval type-2 fuzzy approach

This article scrutinizes the stabilization and fault reconstruction issues for interval type-2 fuzzy-based cyber–physical systems with actuator faults, deception attacks and external disturbances. The primary objective of this research is to formulate the learning observer system with the interval type-2 fuzzy technique that reconstructs the actuator faults as well as the immeasurable states of the addressed fuzzy based model. Further, the information of reconstructed actuator faults is incorporated in the developed controller with the imperfect premise variables for ensuring the stabilization of the system under consideration. At the same time, the H∞ technique is employed to reduce the impact of external disturbances in the considered model. In addition to that, the deception attacks are represented as a stochastic variable that satisfies the Bernoulli distributions. On the ground of this, a set of sufficient criteria is deduced in the context of linear matrix inequalities to affirm the stability of the addressed systems. Furthermore, the requisite gain matrices are computed by resolving the obtained linear matrix inequality based stability criteria. At last, two simulation examples, including the mass–spring–damper system are exhibited to demonstrate the usefulness of analytical findings of the developed strategy.

Modeling and Verification of Uncertain Cyber-Physical System Based on Decision Processes

Currently, there is uncertainty in the modeling techniques of cyber-physical systems (CPS) when faced with the multiple possibilities and distributions of complex system behavior. This uncertainty leads to the system’s inability to handle uncertain data correctly, resulting in lower reliability of the system model. Additionally, existing technologies struggle to verify the activity and safety of CPS after modeling, lacking a dynamic verification and analysis approach for uncertain CPS properties.This paper introduces a generalized possibility decision process as a system model. Firstly, the syntax and semantics of generalized possibility temporal logic with decision processes are defined. Uncertain CPS is extended by modeling it based on time-based differential equations and uncertainty hybrid time automaton. After that, model checking is performed on the properties of activity and safety using fuzzy linear time properties. Finally, a cold–hot hybrid constant-temperature system model is used for simulation experiments. By combining theory and experiments, this paper provides a new approach to the verification of uncertain CPS, effectively addressing the state explosion problem. It plays a crucial role in the design of uncertain CPS and offers a key solution for model checking in the presence of uncertainty.

A REFERENCE ARCHITECTURE OF HUMAN CYBER-PHYSICAL SYSTEMS – PART III: SEMANTIC FOUNDATIONS

The design and analysis of multi-agent human cyber-physical systems in safety-critical or industry-critical domains calls for an adequate semantic foundation capable of exhaustively and rigorously describing all emergent effects in the joint dynamic behavior of the agents that are relevant to their safety and well-behavior. We present such a semantic foundation. This framework extends beyond previous approaches by extending the agent-local dynamic state beyond state components under direct control of the agent and belief about other agents (as previously suggested for understanding cooperative as well as rational behavior) to agent-local evidence and belief about the overall cooperative, competitive, or coopetitive game structure. We argue that this extension is necessary for rigorously analyzing systems of human cyber-physical systems because humans are known to employ cognitive replacement models of system dynamics that are both non-stationary and potentially incongruent. These replacement models induce visible and potentially harmful effects on their joint emergent behavior and the interaction with cyber-physical system components.

Methodology for Designing Cyber-Physical Multi-Operation Robot Systems Operating in the Conditions of Digital Robust Control

Abstract The article proposes an original interdisciplinary approach to the design and construction of cyber-physical robot systems for mechanical processing. From a methodological aspect, the goal is the unification of modeling/synthesis and simulation software of a robot system for mechanical processing operating under the conditions of digital robust control. The system includes industrial robots; modules for implementing technological operations and transport systems. Adherence to the principle of modular construction, reconfiguration, and multi-operation ensures high flexibility and quick response when readjusting the system, and the optimization criteria – minimizing idle moves of the robot, leads to a reduction in the work cycle. The robust control, simultaneously in the instrumental, configurational, and system direction, is a counteraction in the mode of uncertainty, both to external signal disturbances and to possible constantly acting, system reparametrizing factors. This creates prerequisites for maintaining and implementing in online mode both the technological and geometric parameters of the details processed.

The Support of MISRA C++ Analyzer for Reliability of Embedded Systems

Cyber-Physical Systems (CPS) are increasingly used in many complex applications, such as autonomous delivery drones, the automotive CPS design, power grid control systems, and medical robotics. However, existing programming languages lack certain design patterns for CPS designs, including temporal semantics and concurrency models. Future research directions may involve programming language extensions to support CPS designs. On the other hand, JSF++, MISRA, and MISRA C++ are providing specifications intended to increase the reliability of safety-critical systems. This article also describes the development of rule checkers based on the MISRA C++ specification using the Clang open-source tool, which allows for the annotation of code and the easy extension of the MISRA C++ specification to other programming languages and systems. This is potentially useful for future CPS language research extensions to work with reliability software specifications using the Clang tool. Experiments were performed using key C++ benchmarks to validate our method in comparison with the well-known Coverity commercial tool. We illustrate key rules related to class, inheritance, template, overloading, and exception handling. Open-source benchmarks that violate the rules detected by our checkers are also illustrated. A random graph generator is further used to generate diamond case with multiple inheritance testdata for our software validations. The experimental results demonstrate that our method can provide information that is more detailed than that obtained using Coverity for nine open-source C++ benchmarks. Since the Clang tool is widely used, it will further allow developers to annotate their own extensions.

A run-time verification method with consideration of uncertainties for cyber–physical systems

Since many Cyber–Physical Systems (CPS) interact with the real world, they are safety- or mission- critical. Temporal specification languages like STL (Signal Temporal Logic) have been developed to capture the properties that built CPS must meet. However, the existing temporal logics/languages do not provide a natural way to express the tolerance with which the timing properties must be met. As a consequence of this, the specified properties may be vague, the ensuing CPS design may end up being over- or under-provisioned, and the validation of whether the built CPS meets the specified CPS properties may turn out to be erroneous. To address these issues, a run-time verification methodology is proposed, that allows users to explicitly specify the tolerance with which timing properties must be met. To ensure the correctness of measurement-based validation of a built CPS, this article: (i) proposes a test to determine if a given measurement system can validate the properties specified in TTL, and (ii) proposes a measurement-based testing methodology to provide one-sided guarantee that the built CPS meets the specified CPS properties. The guarantees are one-sided in the sense that when the measurement-based testing concludes that the properties are met, then they are guaranteed to be met (so not false positive). However, when the measurement-based testing concludes that the properties were not met, then they may have met (there can be false negative). In order to validate our claims, we built a model of flying paster (part of the printing press that swaps in a new roll of paper when the current roll is about to finish) using Arduino Mega 2560 and two Hansen brushed DC motors and specified the timing constraints among the various events in this system, along with the tolerances with which they should be met in TTL. We generated the testing logic and validated that we get no false positive, even though we encounter 4.04% false negative. The rate of false negatives can be reduced to be less than any arbitrary value by using more accurate measurement equipment.

Decomposition of a Petri Net-Based Cyber-Physical System toward Implementation as an Integrated System within FPGA

Decomposition is one of the commonly used techniques applied in the design of Petri net-based cyber-physical systems. Such an operation permits the splitting of the initial system into sequential components that can be further implemented as an integrated or distributed system. This paper is focused on the decomposition of the modelled CPS toward its further implementation as an integrated system, namely an FPGA device. The adequate decomposition method is presented and explained in detail. Moreover, the proposed idea is explained by the real-life example of the beverage production and distribution system. The results of the experiments are presented and discussed.