Systems Modeling Language Diagrams Research Articles

Integration of SysML and Virtual Reality Environment: A Ground Based Telescope System Example

In recent years, Model Based Systems Engineering (MBSE) has continued to develop as a standard for designing, managing, and maintaining increasingly complex systems. Unlike the document centric approach, MBSE puts the model at the heart of system design. Among the various MBSE language development efforts, “Systems Modeling Language (SysML)”, is the most anticipated and broadly utilized in the research and in industrial practice. SysML originated from Unified Modeling Language (UML) and follows the Object-Oriented Systems Engineering Method (OOSEM). SysML diagrams help users create various systems engineering artifacts, including requirements, use cases, operational concepts, system architecture, system behaviors, and parametric analyses of a system model. In the early days of implementation, MBSE languages, including SysML, typically relied on static viewpoints and limited simulation support to depict and analyze a system model. Due the continuous improvement efforts and new implementation approaches by researchers and organizations, SysML has advanced vastly to encompass dynamic viewpoints, in-situ simulation and enable integration with external modeling and simulation (M&S) tools. Virtual Reality (VR) has emerged as a user interactive and immersive visualization technology and can depict reality in a virtual environment at different levels of fidelity. VR can play a crucial role in developing dynamic and interactive viewpoints to improve the MBSE approach. In this research paper, the authors developed and implemented a methodology for integrating SysML and VR, enabling tools to achieve three dimensional viewpoints, an immersive user experience and early design evaluations of the system of interest (SOI). The key components of the methodology being followed in this research paper are the SysML, a VR environment, extracted data and scripting languages. The authors initially developed a SysML for a ground-based telescope system following the four pillars of SysML: Structure, Requirements, Behavior and Parametrics. The SysML diagram components are exported from the model using the velocity template language and then fed into a virtual reality game engine. Then, the SysML diagrams are visualized in the VR environment to enable better comprehension and interaction with users and Digital Twin (DT) technologies. In addition, a VR simulation scenario of space objects is generated based on the input from the SysML, and the simulation result is sent back from the VR tool into the model with the aid of parametric diagram simulation. Hence, by utilizing the developed SysML-VR integration methodology, VR environment scenarios are successfully integrated with the SysML. Finally, the research paper mentions a few limitations of the current implementation and proposes future improvements.

Self-Adaptation Driven by SysML and Goal Models -- A Literature Review

Background: Socio-cyber-physical systems (SCPSs) are a type of cyber-physical systems with social concerns. Many SCPSs, such as smart homes, must be able to adapt to reach an optimal symbiosis with users and their contexts. The Systems Modeling Language (SysML) is frequently used to specify ordinary CPSs, whereas goal modeling is a requirements engineering approach used to describe and reason about social concerns. Objective: This paper aims to assess existing modeling techniques that support adaptation in SCPSs, and in particular those that integrate SysML with goal modeling. Method: A systematic literature review presents the main contributions of 52 English articles selected from five databases that use both SysML and goal models (17 techniques), SysML models only (11 techniques), or goal models only (8 techniques) for analysis and self-adaptation. Result: Existing techniques have provided increasingly better modeling support for adaptation in a SCPS context, but overall analysis support remains weak. The techniques that combine SysML and goal modeling offer interesting benefits by tracing goals to SysML (requirements) diagrams and influencing the generation of predefined adaptation strategies for expected contexts, but few target adaptation explicitly and most still suffer from a partial coverage of important goal modeling concepts and of traceability management issues.

Automatic Formal Verification of SysML State Machine Diagrams for Vehicular Control Systems

<div class="section abstract"><div class="htmlview paragraph">Vehicular control systems are characterized with numerous complex interactions with a steady rise of autonomous functions, which makes it more challenging for designers and safety engineers to identify unexpected failures. These systems tend to be highly integrated and exhibit features like concurrency for which traditional verification and validation techniques (i.e. testing and simulation) are insufficient to provide rigorous and complete assessment. Model Checking, a well-known formal verification technique, can be used to rigorously prove the correctness of such systems according to design Requirements. In particular, Model Checking is a method for formally verifying finite-state concurrent systems. Specifications about the system are expressed as temporal logic formulas, and efficient symbolic algorithms are used to traverse the model defined by the system and check if the specification holds or not. Systems Modeling Language (SysML) has been widely used in architectural and functional modeling in automotive industries. However, it cannot directly be verified against safety requirements. In this work, SysML is used to establish a unified system model that can present an integrated autonomy software and hardware system of a vehicular control system. A generic model transformation strategy is developed to integrate SysML with one of the state-of-the-art Model Checking tools, NuSMV. Cameo Systems Modeler is an industry leading cross-platform collaborative Model-Based Systems Engineering environment for designing standard-compliant SysML models and diagrams. A native Cameo's plugin is constructed to transform SysML state machines to the input language of NuSMV model checker and also to replay the verification results back into the Cameo's environment. A case study of an executable state machine for a high-level autonomous driving system is built. The NuSMV model checker is used to model check the state machine of the autonomous driving system against design requirements expressed as temporal logic formulas. Upon violation of design requirements, our SysML-NuSMV integration allows to replay counterexamples in the Cameo modeling environment. Thus a bi-directional integration of system modeling language with the model checker is developed and the transformation rules are defined. The case study result shows how this method can help designers and safety engineers to automatically identify hidden design errors in a variety of possible design models.</div></div>

Mapping SysML Diagrams Into Bayesian Networks: A Systems Engineering Approach for Fault Diagnosis

Abstract The growing complexity of equipment and systems has motivated the search for automated methods of fault diagnosis. Fault diagnosis represents the process of identifying the origin of a fault through the observation of a series of effects that it causes in the system. The method proposed in this paper for system fault diagnosis takes advantage of two very different techniques: Bayesian networks (BN) and systems modeling language (SysML). SysML allows the modeling of requirements, structure, behavior and parameters to provide a robust description of a system, its components, and its environment. This system model is used, in the proposed method, to obtain the BN graph in a novel structured procedure. The BN graph obtained must, in turn, present the components that are most likely responsible for a certain fault of the system under study. The BN model uses components reliabilities to solve the diagnosis problem. A case study of a water storage system is presented and it shows how the method can contribute to an assessment of the monitoring process of a system even in the early stages of its design. With this kind of information, the designer can assess the need for changes in the system to make it more reliable or better monitored.

A Unified Model-Based Framework for the Simplified Execution of Static and Dynamic Assertion-Based Verification

The improved productivity and reduced time-to-market are essential requirements for the development of modern embedded systems and, therefore, the comprehensive as well as timely design verification is critical. Assertion Based Verification (ABV) is a renowned paradigm to timely achieve an optimum test coverage, either through static or dynamic techniques. However, the major limitation with ABV is its inherited low-level implementation complexity. In order to simplify its execution, various Model Based System Engineering approaches provide a higher abstraction layer. Nevertheless, the complete verification requirements, targeting the static as well as dynamic ABV at the same time in a unified framework, are not being addressed. Furthermore, the dynamic verification support is provided through some traditional languages (like C, Verilog) where the advanced ABV features cannot be exploited. Consequently, this article introduces the MODEVES (MOdel-based DEsign Verification for Embedded Systems) framework to simultaneously support the static and dynamic ABV. Particularly, the UML (Unified Modeling Language) and SysML (Systems Modeling Language) diagrams are used to model the structural and behavioral requirements. Moreover, the NLCTL (Natural Language for Computation Tree Logic) is proposed to include the verification requirements for static ABV while the SVOCL (SystemVerilog in Object Constraint Language) is used to represent the dynamic verification constraints. An open source transformation engine is developed to automatically generate the SystemVerilog Register Transfer Level (RTL) code, Timed Automata model, SystemVerilog assertions and Computation Tree Logic (CTL) assertions with minimum transformation losses. The significance of the MODEVES framework is established through several case studies and the quantitative analysis shows an improvement of almost 100% in design productivity, as compared to the conventional low-level implementations.

Transformation of SysML Requirement Diagram into OWL Ontologies

The Requirement Diagrams are used by the System Modeling Language (SysML) to depict and model non-functional requirements, such as response time, size, or system functionality, which cannot be accommodated in the Unified Modeling Language (UML). Nevertheless, SysML still lacks the capability to represent the semantic contexts within the design. Web Ontology Language (OWL) can be used to capture the semantic context of system design; hence, the transformation of SysML diagrams into OWL is needed. The current method of SysML Diagrams transformation into OWL is still done manually so that it is very vulnerable to errors, and the translation process requires more time and effort for system engineers. This research proposes a model that can automatically transform a SysML Requirement Diagram into an OWL file so that system designs can be easily understood by both humans and machines. It also allows users to extract knowledge contained in the previous diagrams. The transformation process makes use of a transformation rule and an algorithm that can be used to change a SysML Requirement Diagram into an OWL ontology file. XML Metadata Interchange (XMI) serialization is used as the bridge to perform the transformation. The produced ontology can be viewed in Protege. The class and subclass hierarchy, as well as the object properties and data properties, are clearly shown. In the experiment, it is also shown that the model can conduct the transformation correctly.

Enhancing Knowledge Management into Systems Engineering through New Models in SysML

This paper aims at exploring cooperative work and knowledge implication into Systems Engineering approach in order to study organisational impact. Furthermore, the study aims at providing conceptual models that enhance a Model-Based Systems Engineering (MBSE) with the purpose of taking into account knowledge management (KM). The research formulates a decision model that complements the existing methods through Systems Modeling Language (SysML). The methodology is based on current SysML diagrams and proposes a KM solution focused on an organizational approach. The requirements satisfaction is built on this conceptual approach to help on the decisional process. Systems Engineering (SE) integrates all the disciplines and specialty groups into a team effort forming a structured development process from design to production. SE shows that cooperative work and management increase with the complexity of systems. Thus far, the current models do not present enough cooperative and knowledge management supports. The study proposes to add a new model to imply KM and organizational aspect through SysML in order to develop a cooperative work process with a first conceptual approach. This paper tackles several possibilities based on modeling language SysML extension and discusses the interest of implementing the model while providing a complementary decision-making tool.

Performing System Tradeoff Analyses Using Human Performance Modeling

Humans perform critical functions in nearly every system, making them vital to consider during system development. Human Systems Integration (HSI) would ideally permit the human’s impact on system performance to be effectively accounted for during the systems engineering (SE) process, but effective processes are often not applied, especially in the early design phases. Failure to properly account for human capabilities and limitations during system design may lead to unreasonable expectations of the human. The result is a system design that makes unrealistic assumptions about the human, leading to an overestimation of the human’s performance and thus the system’s performance. This research proposes a method of integrating HSI with SE that allows human factors engineers to apply Systems Modeling Language (SysML) and human performance simulation to describe and communicate human and system performance. Using these models, systems engineers can more fully understand the system’s performance to facilitate design decisions that account for the human. A scenario is applied to illustrate the method, in which a system developer seeks to redesign an example system, Vigilant Spirit, by incorporating system automation to improve overall system performance. The example begins by performing a task analysis through physical observation and analysis of human subjects’ data from 12 participants employing Vigilant Spirit. This analysis is depicted in SysML Activity and Sequence Diagrams. A human-in-the-loop experiment is used to study performance and workload effects of humans applying Vigilant Spirit to conduct simulated remotely-piloted aircraft surveillance and tracking missions. The results of the task analysis and human performance data gathered from the experiment are used to build a human performance model in the Improved Performance Research Integration Tool (IMPRINT). IMPRINT allows the analyst to represent a mission in terms of functions and tasks performed by the system and human, and then run a discrete event simulation of the system and human accomplishing the mission to observe the effects of defined variables on performance and workload. The model was validated against performance data from the human-subjects’ experiment. In the scenario, six different scan algorithms, which varied in terms of scan accuracy and speed, were simulated. These algorithms represented different potential system trades as factors such as various technologies and hardware architectures could influence algorithm accuracy and speed. These automation trades were incorporated into the system’s block definition (BDD), requirements, and parametric SysML diagrams. These diagrams were modeled from a systems engineer’s perspective; therefore they originally placed less emphasis on the human. The BDD portrayed the structural aspect of Vigilant Spirit, to include the operator, automation, and system software. The requirements diagram levied a minimum system-level performance requirement. The parametric diagram further defined the performance and specification requirements, along with the automation’s scan settings, through the use of constraints. It was unclear from studying the SysML diagrams which automation setting would produce the best results, or if any could meet the performance requirement. Existing system models were insufficient by themselves to evaluate these trades; thus, IMPRINT was used to perform a trade study to determine the effects of each of the automation options on overall system performance. The results of the trade study revealed that all six automation conditions significantly improved performance scores from the baseline, but only two significantly improved workload. Once the trade study identified the preferred alternative, the results were integrated into existing system diagrams. Originally system-focused, SysML diagrams were updated to reflect the results of the trade analysis. The result is a set of integrated diagrams that accounts for both the system and human, which may then be used to better inform system design. Using human performance- and workload-modeling tools such as IMPRINT to perform tradeoff analyses, human factors engineers can attain data about the human subsystem early in system design. These data may then be integrated into existing SysML diagrams applied by systems engineers. In so doing, additional insights into the whole system can be gained that would not be possible if human factors and systems engineers worked independently. Thus, the human is incorporated into the system’s design and the total system performance may be predicted, achieving a successful HSI process.

Automated transformation of design text ROM diagram into SysML models

This paper proposes an approach to generating System Modeling Language (SysML) diagrams from a Recursive Object Model (ROM) diagram. The ROM diagram represents entities (or concepts) and three kinds of relations between these entities found in a description text. The generated SysML models include block definition diagram, use case diagram, and activity diagram. Since the SysML is becoming a standard modeling language for specifying, analyzing, designing and verifying complex design in many industry sectors, this transformation process supports knowledge representations of design documents for next generation CAD systems. The proposed approach first analyzes the features of ROM and SysML diagrams and then defines transition rules that transform a ROM diagram into SysML models. A software prototype ROM2SysML is developed based on the proposed approach and two examples are used to demonstrate how the prototype works.

Integrating External Simulations Within the Model-Based Systems Engineering Approach Using Statistical Metamodels

The Model-Based Systems Engineering (MBSE) approach uses the Systems Modeling Language (SysML) to express the architectural information of a system throughout different stages of its lifecycle. Within the approach, the system's structure, behavior, requirements, and parametrics are defined as elements within an integrated model. System Engineers use nine SysML diagrams to display unique views of these system elements. A significant limitation of SysML is that it is only descriptive in nature and cannot produce analytical results to inform system effectiveness. In order to achieve the full benefit of the MBSE approach the systems engineering community must also rely on external models that capture more sophisticated analysis across a wide variety of domains. These domain models include simulations that measure operational effectiveness, life cycle costing models, physics-based computational simulations, manufacturing models, and many more. The purpose of this paper is to propose an approach that integrates these external simulation models with the MBSE integrated model using statistical metamodels that act as surrogates to the simulations. We demonstrate the approach using a simple system design problem and an agent-based simulation.

On the formal interpretation and behavioural consistency checking of SysML blocks

The Systems Modeling Language (SysML) is a semi-formal, graphical modelling language used in the specification and design of systems. We describe how Communicating Sequential Processes (CSP) and its associated refinement checker, FDR3, may be used to underpin an approach that facilitates the refinement checking of the behavioural consistency of SysML diagrams. We achieve this by utilising CSP as a semantic domain for reasoning about SysML behavioural aspects: activities and state machines are given a formal, process-algebraic semantics. These behaviours execute within the context of the structural diagrams to which they relate, and this is reflected in the CSP descriptions that depict their characteristic patterns of interaction. We describe how CSP and FDR3 can be used in conjunction with SysML in a formal, top-down approach to systems engineering. Moreover, the compositionality afforded by CSP alleviates the state space explosion problem frequently encountered with complex formal models and complements the top-down approach of SysML. Typically, a system is composed from constituent systems using the concept of blocks. SysML permits two alternative interpretations with regard to the behaviour of the resulting composition. We argue that the use of a process-algebraic formalism enables us to explore the relationships between these interpretations in a more rigorous fashion than would otherwise be the case.