System-of-systems Research Articles

IQCPSoS: A Model-Based Approach for Modeling and Analyzing Information Quality Requirements for Cyber-Physical System-of-Systems

A Cyber-Physical System-of-Systems (CPSoS) can be defined as a System-of-Systems (SoS), where its component systems are Cyber-Physical Systems (CPSs) that have been networked together for achieving a certain higher goal. Therefore, a key viability of any CPSoS is the integration of its CPSs to function as a single integrated system to support a common mission. Although such integration can be achieved relying on the exchange of information among CPSs, only few works have highlighted the importance of considering the quality of such information. Without considering Information Quality (IQ) requirements during the design of CPSoS, CPSs will be vulnerable to faults arising from depending on inaccurate, incomplete, inconsistent, and/or outdated information, which may influence the overall dependability, reliability, and performance of the CPSoS. This paper proposes a model-based approach that offers a novel UML profile, named IQCPSoS (Information Quality for Cyber-Physical System-of-Systems), which contains various stereotypes and tagged values for modeling and analyzing IQ requirements for CPSoS. The profile also proposes a set of constraints expressed in the Object Constraint Language (OCL) to be used for the verification of such models. We evaluate our approach by developing a prototype implementation and test its applicability, usability, and validity for modeling and analyzing IQ requirements for a realistic scenario concerning a Tram system.

Proposition of an ontology to support product service systems of systems engineering

AbstractThe venue of new technologies such as autonomous vehicles implies the design not only of the product but also of services related to it. These systems are known as Product Service Systems (PSS). Moreover, they are not only PSS but also System of Systems (SoS). Up till now, research has been addressing the design of PSS and SoS separately. The PSS literature focuses mainly on the product servitization and the increasing heterogeneity of PSS elements. On the other hand, the SoS literature focuses on the relationships between SoS constituent systems and their management. Both research domains propose systems modeling approaches and systems architectural patterns independently according to PSSs and SoS development contexts. In order to address this gap and support PSSoS design and development, there is a need to identify necessary data, the PSSoS ontology. The proposed ontology is developed with the Unified Modeling Language (UML) and is structured in four views: the stakeholder view, the service view, the systems view, and the operational view. The proposed model has been validated by nine industrial experts as well as five industrial projects; and is illustrated via the case of Plug&Charge within one of the major automotive French constructors.

Exploring System of Systems Resilience Versus Affordability Trade-Space Using a Bio-Inspired Metric

Abstract The objective of this study is to investigate the value of an ecologically inspired architectural metric called the degree of system order in the system of systems (SoS) architecting process. Two highly desirable SoS attributes are the ability to withstand and recover from disruptions (resilience) and affordability. In practice, more resilient SoS architectures are less affordable, and it is essential to balance the trade-offs between the two attributes. Ecological research analyzing long-surviving ecosystems (nature’s resilient SoS) using the degree of system order metric has found a unique balance of efficient and redundant interactions in their architecture. This balance implies that highly efficient ecosystems tend to be inflexible and vulnerable to perturbations, while highly redundant ecosystems fail to utilize resources effectively for survival. Motivated by this unique architectural property of ecosystems, this study investigates the response to disruptions versus affordability trade space of a large number of feasible SoS architectures. Results indicate that the most favorable SoS architectures in this trade space share a specific range of values of degree of system order. This suggests that degree of system order can be a key metric in engineered SoS development. Evaluating the degree of system order does not require detailed simulations and can, therefore, guide the early-stage SoS design process toward more optimal SoS architectures.

Handling Quantity in Variability Models for System-of-Systems

Problem: Modern systems contain parts that are themselves systems. Such complex systems thus have sets of subsystems that have their own variability. These subsystems contribute to the functionality of a whole system-of-systems (SoS). Such systems have a very high degree of variability. Therefore, a modeling technique for the variability of an entire SoS is required to express two different levels of variability: variability of the SoS as a whole and variability of subsystems. If these levels are described together, the model becomes hard to understand. When the variability model of the SoS is described separately, each variability model is represented by a tree structure and these models are combined in a further tree structure. For each node in a variability model, a quantity is assigned to express the multiplicity of its instances per one instance of its parent node. Quantities of the whole system may refer to the number of subsystem instances in the system. From the viewpoint of the entire system, constraints and requirements written in natural language are often ambiguous regarding the quantities of subsystems. Such ambiguous constraints and requirements may lead to misunderstandings or conflicts in an SoS configuration. Approach: A separate notion is proposed for variability of an SoS; one model considers the SoS as an undivided entity, while the other considers it as a combination of subsystems. Moreover, a domain-specific notation is proposed to express relationships among the variability properties of systems, to solve the ambiguity of quantities and establish the total validity. This notation adapts an approach, named Pincer Movement, which can then be used to automatically deduce the quantities for the constraints and requirements. Validation: The descriptive capability of the proposed notation was validated with four examples of cloud providers. In addition, the proposed method and description tool were validated through a simple experiment on describing variability models with real practitioners.

A Breakdown of System of Systems Needs Using Architecture Frameworks, Ontologies and Description Logic Reasoning

Aerospace systems are connected with the operational environment and other systems in general. The focus in aerospace product development is consequently shifting from a singular system perspective to a System-of-Systems (SoS) perspective. This increasing complexity gives rise to new levels of uncertainty that must be understood and managed to produce aerospace solutions for an ever-changing future. This paper presents an approach to using architecture frameworks, and ontologies with description logic reasoning capabilities, to break down SoS needs into required capabilities and functions. The intention of this approach is to provide a consistent way of obtaining the functions to be realized in order to meet the overarching capabilities and needs of an SoS. The breakdown with an architecture framework results in an initial design space representation of functions to be performed. The captured knowledge is then represented in an ontology with description logic reasoning capabilities, which provides a more flexible way to expand and process the initial design space representation obtained from the architecture framework. The proposed approach is ultimately tested in a search and rescue case study, partly based on the operations of the Swedish Maritime Administration. The results show that it is possible to break down SoS needs in a consistent way and that ontology with description logic reasoning can be used to process the captured knowledge to both expand and reduce an available design space representation.

Security Standard Compliance Verification in System of Systems

Standard compliance in system of systems (SoS) means complying with standards, laws, and regulations that apply to services from several sources and different levels. Compliance is a major challenge in many organizations because any violation will lead to financial penalties, lawsuits fines, or revocation of licenses to operate within specific industrial market. To support the business lifecycle, organizations also need to monitor the actual processes during run time and not only in their design time. Standard compliance verification is important in the lifecycle for reasons, such as detection of noncompliance as well as operational decisions of running processes. With the promotion of connectivity of systems, existing and new security standards can be employed but there are important aspects, such as technically measurable indicators, in the standards and automation of compliance verification that need to be addressed. This article presents an automated and continuous standard compliance verification framework used to check devices, systems, and services for standard compliance during secure onboarding and run time. In addition, a case study for the Eclipse Arrowhead framework is used to demonstrate the functionality of the standard compliance verification in SoS.

System of Systems Lifecycle Management—A New Concept Based on Process Engineering Methodologies

In order to tackle interoperability issues of large-scale automation systems, SOA (Service-Oriented Architecture) principles, where information exchange is manifested by systems providing and consuming services, have already been introduced. However, the deployment, operation, and maintenance of an extensive SoS (System of Systems) mean enormous challenges for system integrators as well as network and service operators. The existing lifecycle management approaches do not cover all aspects of SoS management; therefore, an integrated solution is required. The purpose of this paper is to introduce a new lifecycle approach, namely the SoSLM (System of Systems Lifecycle Management). This paper first provides an in-depth description and comparison of the most relevant process engineering methodologies and ITSM (Information Technology Service Management) frameworks, and how they affect various lifecycle management strategies. The paper’s novelty strives to introduce an Industry 4.0-compatible PLM (Product Lifecycle Management) model and to extend it to cover SoS management-related issues on well-known process engineering methodologies. The presented methodologies are adapted to the PLM model, thus creating the recommended SoSLM model. This is supported by demonstrations of how the IIoT (Industrial Internet of Things) applications and services can be developed and handled. Accordingly, complete implementation and integration are presented based on the proposed SoSLM model, using the Arrowhead framework that is available for IIoT SoS.

Time Granularity Impact on Propagation of Disruptions in a System-of-Systems Simulation of Infrastructure and Business Networks.

A system-of-systems (SoS) approach is often used for simulating disruptions to business and infrastructure system networks allowing for integration of several models into one simulation. However, the integration is frequently challenging as each system is designed individually with different characteristics, such as time granularity. Understanding the impact of time granularity on propagation of disruptions between businesses and infrastructure systems and finding the appropriate granularity for the SoS simulation remain as major challenges. To tackle these, we explore how time granularity, recovery time, and disruption size affect the propagation of disruptions between constituent systems of an SoS simulation. To address this issue, we developed a high level architecture (HLA) simulation of three networks and performed a series of simulation experiments. Our results revealed that time granularity and especially recovery time have huge impact on propagation of disruptions. Consequently, we developed a model for selecting an appropriate time granularity for an SoS simulation based on expected recovery time. Our simulation experiments show that time granularity should be less than 1.13 of expected recovery time. We identified some areas for future research centered around extending the experimental factors space.

Enhancing semantic belief function to handle decision conflicts in SoS using k-means clustering.

BackgroundThe endeavouring to offer complex special functions from individual systems gave rise to what is known as the System of Systems (SoS). SoS co-integrating systems together while allowing for absorbing more systems in the future. SoS as an integrated system simplifies operations, reduces costs, and ensures efficiency. However, conflict may result while co-integrating systems, violating the main benefits of SoS. This paper is concerned with enhancing the time required to detect and solve such conflicts.MethodsWe adopted the k-means clustering technique to enhance the detection and solving of conflict resulting while co-integrating new systems into an existing SoS. Instead of dealing with SoS as a single entity, we partition it into clusters. Each cluster contains nearby systems according to pre-specified criteria. We can consider each cluster a Sub SoS (S-SoS). By doing so, the conflict that may arise while co-integrating new systems can be detected and solved in a shorter time. We propose the Smart Semantic Belief Function Clustered System of Systems (SSBFCSoS), which is an enhancement of the Ontology Belief Function System of Systems (OBFSoS).ResultsThe proposed method proved the ability to rapidly detect and resolve conflicts. It showed the ability to accommodate more systems as well, therefore achieving the objectives of SoS. In order to test the applicability of the SSBFCSoS and compare its performance with other approaches, two datasets were employed. They are (Glest & StarCraft Brood War). With each dataset, 15 test cases were examined. We achieved, on average, 89% in solving the conflict compared to 77% for other approaches. Moreover, it showed an acceleration of up to proportionality over previous approaches for about 16% in solving conflicts as well. Besides, it reduced the frequency of the same conflicts by approximately 23% better than the other method, not only in the same cluster but even while combining different clusters.

A Complex Network Framework for Validated Assessments of Systems of Systems Robustness

The complexity of modern systems of systems (SoS) requires the ability to quickly and effectively evaluate robustness in architecture alternatives. This article presents a framework for rapid, quantitative comparisons of robustness in SoS architectures that leverages complex network methods for assessing robustness and design of experiments (DoE) techniques for validating their use in the scenario of interest. We consider both single-layer and multilayer network representations of SoS and focus on algebraic connectivity, inverse average path length, and largest connected component size as measures of robustness. Two case studies are used to illustrate our framework and assess its utility: a command, control, communications, computer, intelligence, surveillance, and reconnaissance (C4ISR) simulation and a multilayer message-passing network simulation. We find that most of the considered network metrics capture expected robustness trends, though their ability to capture these trends is often affected by the scenario of interest. These results demonstrate the potential value of complex network methods for lightweight analysis of robustness in SoS architecture alternatives, when appropriately supported by DoE methods for understanding their limitations.

Towards a Domain-Specific Approach Enabling Tool-Supported Model-Based Systems Engineering of Complex Industrial Internet-of-Things Applications

Contemporary manufacturing systems are undergoing a major change promoted by emerging technologies such as Cyber-physical Systems (CPS) or the Internet of Things (IoT). This trend, nowadays widely known by the term “Industry 4.0”, leads to a new kind of automated production. However, the rising number of dynamically interconnected elements in industrial production lines results in such a system being transformed into a complex System of Systems (SoS). Due to the increasing complexity and the challenges accompanied by this change, conventional engineering methods using generic principles reach their limits when developing this type of systems. With varying approaches only trying to find a solution for small-scaled areas of this problem statement, the need for a holistic methodology becomes more and more obvious. Having recognized this issue, one of the most promising approaches has been introduced with the Reference Architecture Model Industry 4.0 (RAMI 4.0). However, in the current point of view, this domain-specific architecture framework is missing specifications to address all aspects of such a critical infrastructure. Thus, this paper introduces a comprehensive modeling approach utilizing methods applied in Model-Based Systems Engineering (MBSE) and including domain-specific particularities as well as architectural concepts with the goal to enable mutual engineering of current and future industrial systems. The resulting artifacts, a domain-specific language (DSL), an architecture definition and a development process, are thereby consolidated in a ready to use software framework, whose applicability was evaluated by a real-world case study.

The Applicability of Big Data in Climate Change Research: The Importance of System of Systems Thinking

The aim of this paper is to provide an overview of the interrelationship between data science and climate studies, as well as describes how sustainability climate issues can be managed using the Big Data tools. Climate-related Big Data articles are analyzed and categorized, which revealed the increasing number of applications of data-driven solutions in specific areas, however, broad integrative analyses are gaining less of a focus. Our major objective is to highlight the potential in the System of Systems (SoS) theorem, as the synergies between diverse disciplines and research ideas must be explored to gain a comprehensive overview of the issue. Data and systems science enables a large amount of heterogeneous data to be integrated and simulation models developed, while considering socio-environmental interrelations in parallel. The improved knowledge integration offered by the System of Systems thinking or climate computing has been demonstrated by analysing the possible inter-linkages of the latest Big Data application papers. The analysis highlights how data and models focusing on the specific areas of sustainability can be bridged to study the complex problems of climate change.

Towards a Software Architecture for Internet of Things based System of Systems

The Smart City vision is becoming a reality with the widespread adaption of Internet of Things (IoT). In this context, several architectural styles like service-oriented and microservice architecture have widely been used in the development of IoT-based systems. However, less amount of work is done for IoT-based system of systems. The recognition of system of systems (SoS) as a system with its unique features such as operationally and administratively independence has been considered a new trend of distributed software systems. The collaboration of the SoS independent system helps to build a larger and more complex system. The characteristics and domain constraints of SoS make some quality attributes critical, especially when SoS is based on IoT. These quality attributes should be considered while designing such systems. To fill this gap, this article presents a novel software architecture based on microservices architectural style, while considering the important quality attributes required for IoT-based SoS. The applicability of the proposed architecture is demonstrated through a smart city case study. In addition, the design quality is evaluated in terms of scalability and maintainability. The results show that the design developed using the proposed architecture is better in terms of these two quality attributes than the existing approach.

Importance Measure of Equipment Task Based on Operational Dependency of SoS

In order to evaluate the mission success of system of systems (SoS) and to develop maintenance strategies to meet mission requirements of SoS, an importance measure method of equipment task based on operational dependency of SoS is proposed. The operational dependency network of SoS is constructed based on FDNA, and the nodes and dependency relationships in the network are determined. According to the Markov process, the reliability model of a system function is constructed, and the operability level and probability of each node in the network are obtained. Meanwhile, the algorithm of Birnbaum importance measure is introduced to effectively quantify the impact of operational dependency on the task importance of each equipment system in SoS. Finally, the feasibility and effectiveness of this method is verified by a case study.

Management analysis of the logistics support system-of-systems of US aircraft carrier formation

The US aircraft carrier formation is a complex system-of -systems (SoS). Taking the logistics support organization system of the U.S. aircraft carrier as an example, the scientific management of logistics support SoS is discussed in this paper. Through the detailed discussion and analysis of the command relationship of the US aircraft carrier logistics support organization, as well as the discussion of the responsibility relationship of the U.S. aircraft carrier logistics support organization and its various agencies, the organization and command mode of US aircraft carrier logistics support are discussed. The management characteristics of US aircraft carrier logistics support organization SoS are summarized in detail.

Cybernetics, Complexity, and the Challenges to the Realization of the Internet-of-Things

The realization of the Internet-of-Things (IoT) is a concept that is increasingly discussed as the result of networking a variety of “smart” electronic systems together to achieve high levels of automation and performance. Thus, the IoT is envisioned to enable everything from automated toast buttering for breakfast to fleets of autonomous vehicles co-existing on roads with human piloted vehicles and cooperating with their drivers. However, as more and more systems are linked together to form directed, acknowledged, collaborative, and virtual Systems-of-Systems (SoS), the exercise of control becomes problematic. Emergent properties, hostile agents, evolutionary and adaptive development, and other characteristics of systems will enable complex behaviors in SoS that are not part of the constituent systems. If information theory and cybernetics laws are not considered in the construction of SoS as part of the IoT, then the behaviors that will emerge can have destabilizing outcomes.

Maintaining safety requirements of updated maritime surveillance systems

Abstract The maritime domain is undergoing a transformation away from manual control and navigation towards automated and autonomous vessels controlled by a dedicated software system. These systems are composed out of interdependent and heterogeneous modules, that together form a System of Systems (SoS). Unlike before, these software-based modules allow their functionality to be monitored continuously and changes to be made remotely while in operation. However, adjustments made to devices that have already been approved can cause the existing certification to lose its validity and previously made safety properties may no longer apply. This poses a particular danger when the system is driving autonomously or a navigator is relying on it to function and is unaware of a failure and cannot take alternative action. Especially in case of new functionality being added through adaptive updates, unforeseen errors can occur that were not apparent beforehand. For this reason, a procedure based on assumption-guarantee contracts is presented to verify the impact on the safety properties of a system after an update and outline the required changes to the associated safety case. For this purpose, a safety case based on the Goal Structuring Notation (GSN) is made, whose tree structure has modular properties, so that the effects on the safety behavior can be tracked on a small scale and only partial branches have to be replaced or updated. Moreover, it is shown how a safety case augmented with contracts can meet its safety goals even when the system needs to revert to the state before the update while keeping the vessel operator informed. The concept is demonstrated by extending the functionality of a maritime collision avoidance system by a predictive resolution module and show how in situations missing a valid prediction, the system can still meet its overarching safety goal.

Integration of MBSE and PLM: complexity and uncertainty

Currently, MBSE and PLM methods and solutions are not well aligned with each other resulting in excessive complexity and uncertainty. Their full-scale integration would facilitate the development of complex systems. Better data flow from conceptual design to detailed design and feedback from later stages of product development are needed. In this paper, we analyse the MBSE and PLM integration from a system of systems (SoS) perspective and apply some of the methods used in systems engineering to better understand their nature, quantify their epistemic uncertainty and propose possible solutions to reduce their complexity and uncertainty. To achieve these goals, we study systems ontologies, such as the object-process methodology (OPM), the core product model (CPM), and manufacturing process management (MPM), which represent essential elements of a digital engineering solution. We also propose a measure of complexity to better quantify the structure of the interfaces through the design structure matrix (DSM)-based approach.

System engineering as a methodological basis for designing local learning systems

The article clarifies the classification of the local learning system as an object of design. The article analyzes the own features of the procedure for implementing the system engineering method that ensure its generally recognized success. The features of the classical version of the system engineering method are specified, determined by the orientation to the design of objects of the “complex system " class. The essence of the problem of adapting the classical version of the system engineering method to the design of objects of the “system of systems (SoS)" class is revealed. The latest achievements of system engineering in the study of approaches to ensuring the success of solving the problem of designing humanitarian SoS are stated. The article substantiates the prospects of considering the system engineering method as a methodological tool for designing local learning systems and its development based on pedagogy data.

Automated and Secure Onboarding for System of Systems

The Internet of Things (IoT) is rapidly changing the number of connected devices and the way they interact with each other. This increases the need for an automated and secure onboarding procedure for IoT devices, systems and services. Device manufacturers are entering the market with internet connected devices, ranging from small sensors to production devices, which are subject of security threats specific to IoT. The onboarding procedure is required to introduce a new device in a System of Systems (SoS) without compromising the already onboarded devices and the underlying infrastructure. Onboarding is the process of providing access to the network and registering the components for the first time in an IoT/SoS framework, thus creating a chain of trust from the hardware device to its hosted software systems and their provided services. The large number and diversity of device hardware, software systems and running services raises the challenge to establish a generic onboarding procedure. In this paper, we present an automated and secure onboarding procedure for SoS. We have implemented the onboarding procedure in the Eclipse Arrowhead framework. However, it can be easily adapted for other IoT/SoS frameworks that are based on Service-oriented Architecture (SoA) principles. The automated onboarding procedure ensures a secure and trusted communication between the new IoT devices and the Eclipse Arrowhead framework. We show its application in a smart charging use case and perform a security assessment.