Systems Modeling Language Model Research Articles

Extending SysML to Integrate Cost Analysis Into Model-Based Systems Engineering

Model-based systems design (MBSD), a current trend adopted by INCOSE, employs the systems modeling language (SysML), a standard introduced by OMG and INCOSE. Though there are numerous works on integrating performance exploitation in SysML, cost is not sufficiently explored as a driving design parameter. By integrating cost analysis in a popular modeling language like SysML, the proposed approach may be applied to any system designed using standardized languages and tools. In this work, we integrate cost analysis within SysML models at a generic level to explore design alternatives under specific cost and performance restrictions and perform tradeoff analysis. The proposed SysML extensions provide: 1) cost-related entities to encode cost aspects, such as capital and operating expenses, and 2) functions that enable the automatic computation of costs; these extensions are contained in a custom SysML cost profile. The feasibility and benefits of the approach are explored in two distinct real-world case studies with different purpose and characteristics. 1) Configuring a remote elderly monitoring system, taking into consideration patients' budgetary and operational concerns regarding the equipment installed in their homes. In this case, patients had the opportunity to evaluate and prioritize their concerns prior to using the system. 2) Exploring the improvement of the passengers' comfort as a level of service indicator in the Athens Metro railway system, taking into account operational cost constraints. In this case, the operator obtained forecasts of performance and cost of the metro system operation in order to choose between different operational policies.

System verification via Model‐Checking: A case study of an autonomous multi‐differential drive robot

AbstractModel‐Based Systems Engineering (MBSE) has been utilized in practice to design and behavioral modeling cyber‐physical systems. The Vee model helps frame MBSE's lifecycle approach, with system verification a vital aspect of the qualification process. However, popular modeling language tools in MBSE, such as Systems Modeling Language (SysML), are incapable of formally verifying these systems. Model checking allows for the development of formal system models similar in abstraction to SysML models for automatically checking if these formal models satisfy formal specifications. We propose an approach to translate behavioral diagrams in SysML, such as state‐machine diagrams, to the popular symbolic model checker NuSMV for formal verification. As a case study, we apply this process to autonomous multi‐differential drive robots (DDR). Subsequently, the NuSMV model is verified against some formal operational specifications obtained from the requirements diagram of the DDR. This system verification approach can help System Engineers identify design flaws or incorrect modeling or specifications that could be missed during the design phase through the results of the model checking process.

A SysML-centric integration framework for helicopter fuel system development

Data and model exchange between SysML (Systems Modeling Language) Modeling tools and other system development tools is a critical aspect of Model-Based Systems Engineering (MBSE). This paper introduces an application of the SysML-centric integration framework, which allows integrating multi-disciplinary engineering models into a SysML Modeling environment. A design practice of helicopter fuel system is then presented to illustrate how to combine the external simulation models within the SysML Models to explore the performance and verify corresponding requirements. In this case, FMI (Functional Mock-up Interface) based co-simulation creates a bridge between SysML Modeling tools and simulation tools in the SysML-centric integration framework. According to the practice, we believe it will significantly improve model consistency and traceability to provide early evaluation of concepts during conceptual design phase.

Traceability Management of Socio-Cyber-Physical Systems Involving Goal and SysML Models

Socio-cyber-physical systems (SCPSs) have emerged as networked heterogeneous systems that incorporate social components (e.g., business processes and social networks) along with physical (e.g., Internet-of-Things devices) and software components. Model-driven techniques for building SCPSs need actor and goal models to capture social concerns, whereas system issues are often addressed with the Systems Modeling Language (SysML). Comprehensive traceability between these types of models is essential to support consistency and completeness checks, change management, and impact analysis. However, traceability management between these complementary views is not well supported across SysML tools, particularly when models evolve because SysML does not provide sophisticated out-of-the-box goal modeling capabilities. In our previous work, we proposed a model-based framework, called CGS4Adaptation, that supports basic traceability by importing goal and SysML models into a leading third-party requirement-management system, namely IBM Rational DOORS. In this paper, we present the framework’s traceability management method and its use for automated consistency and completeness checks. Traceability management also includes implicit link detection, thereby, improving the quality of traceability links while better aligning designs with requirements. The method is evaluated using an adaptive SCPS case study involving an IoT-based smart home. The results suggest that the tool-supported method is effective and useful in supporting the traceability management process involving complex goal and SysML models in one environment while saving development time and effort.

Modeling and Analysis of Unmanned Aerial Vehicle System Leveraging Systems Modeling Language (SysML)

The use of unmanned aerial vehicles (UAVs) has seen a significant increase over time in several industries such as defense, healthcare, and agriculture to name a few. Their affordability has made it possible for industries to venture and invest in UAVs for both research and commercial purposes. In spite of their recent popularity; there remain a number of difficulties in the design representation of UAVs, including low image analysis, high cost, and time consumption. In addition, it is challenging to represent systems of systems that require multiple UAVs to work in cooperation, sharing resources, and complementing other assets on the ground or in the air. As a means of compensating for these difficulties; in this study; we use a model-based systems engineering (MBSE) approach, in which standardized diagrams are used to model and design different systems and subsystems of UAVs. SysML is widely used to support the design and analysis of many different kinds of systems and ensures consistency between the design of the system and its documentation through the use of an object-oriented model. In addition, SysML supports the modeling of both hardware and software, which will ease the representation of both the system’s architecture and flow of information. The following paper will follow the Magic Grid methodology to model a UAV system across the SysML four pillars and integration of SysML model with external script-based simulation tools, namely, MATLAB and OpenMDAO. These pillars are expressed within standard diagram views to describe the structural, behavior, requirements, and parametric aspect of the UAV. Finally, the paper will demonstrate how to utilize the simulation capability of the SysML model to verify a functional requirement.

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.

Checking SysML Models Against Safety and Security Properties

Systems engineering, or engineering in general, has long been relying on document-centric approaches. Switching to model-based systems engineering, or MBSE for short, has extensively been discussed over the past three decades. Since about two decades, MBSE has been commonly associated with the modeling language SysML (Systems Modeling Language), which offers a standardized notation, not a methodology of using it. SysML needs therefore to be associated with a methodology supported by tools. In this paper, a methodology supported by the free and open-source software TTool is associated with SysML. This paper focuses discussion on methodological issues, leading the authors to share their experience in real-time systems modeling. Modeling with SysML is more than just drawing the different diagrams. Associated tools offer possibilities to analyze SysML models for specific properties. In this paper, verification addresses both safety and security properties. The TTool model checker inputs the SysML model enriched with safety properties to be verified and outputs an yes/no answer for each property. Security verification checks SysML models against confidentiality, integrity, and authenticity properties. As an illustration of the proposed approach, an aircraft cockpit door control system is modeled in SysML and verified against safety and security properties.

Parametric Evaluation of Internet of Things Applications to Freight Transportation Using Model-Based Systems Engineering

The intended purpose of an intelligent transportation systems (ITS) project is to automate operations through device-to-device connectivity. These devices generally represent stakeholder’s endpoints and expose interfaces to automated operations. Current trends in communication allow more applications and devices to perform functions traditionally allocated to the transportation ITS infrastructure. This connected environment of industrial internet of things presents design challenges because of the diversity of stakeholders, interfaces, and the messages among them. This may require new ways in which ITS planning can handle the scale and complexity of these highly connected systems. This work focuses on the modeling of the architecture of a freight-focused ITS application, including maritime ports. The proposed model integrates stakeholders, behaviors, and messages using the Systems Modeling Language (SysML). The key contribution of this work is to demonstrate the creation of an executable SysML model for an ITS application without sacrificing the typical Systems Engineering Management Plan artifacts (e.g., requirements traceability matrices and interface control documents). At the same time, the proposed model provides a re-usable pattern to support parametric analysis of candidate architectures with respect to any measure of effectiveness. This allows establishing a single source of architecture definition and having multiple architecture specializations depending on the measure of effectiveness being evaluated. Recommendations for implementation and integration with existing ITS tools are provided.

Evaluation of Requirements Management Processes Utilizing System Modeling Language (SysML) Executable Models

AbstractLike many project processes, requirements management can be time consuming and costly if not well planned. The fundamentals of the process steps can be obtained through literature search, however the variation of application can lead to program cost challenges if not tailored for the project's risk posture and budget scope. This paper investigates various published requirements management processes, presents a fundamental process model, demonstrates a method to capture the process steps using a Systems Modeling Language (SysML), and shows the results of a simulation of the process steps enabling a comparison of outcomes for a project. This method investigates an option of using duration constraints to calculate labor hours based on process steps, and uses inputs from the project's requirement data to provide a method of calculating systems engineering labor hours utilizing the Constructive Systems Engineering Cost Model (COSYSMO) in a SysML model. This work is intended to show how SysML can be used to support development and refinement of project processes in general, with specific focus on how this method can enable implementation of requirements management in a way that provides insight into potential cost and schedule impacts to the project.

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>

Multi-domain simulation utilizing SysML: state of the art and future perspectives

Increasing system complexity requires adapted methodologies to tackle the challenges that come along with multi-domain systems development. Model-Based Systems Engineering (MBSE) provides significant support by using models to describe different aspects of an examined system already in the early stages of the development process. The Systems Modeling Language (SysML) can be utilized to establish a common system information basis on a comparatively abstract level for all participating stakeholders. Although SysML models are able to encompass system information like requirements, structure, behaviour and parametrics, in many cases additional specialized simulation or computation models are needed, especially for early design decision-making and verification activities. Ideally, the input data and the calculated results are automatically exchanged between the SysML modelling editor and the involved simulation tools. Hence, tool chain integration is a crucial factor to provide the necessary interconnectivity to achieve multi-domain simulation. In general, the integration of simulation environments with SysML tools is mainly limited by two factors. First, as the tools available for modelling with SysML are legion, interface solutions are usually developed for a specific tool and therefore, their usage is restricted to that particular software. Second, evolving standards like the Functional Mock-up Interface (FMI) provide capabilities to ease model data exchange and co-simulation, but the implementation of different versions of various standards in the tools causes incompatibilities. In this work a state of the art of the integration between simulation environments and available SysML modelling tools with respect to utilized standards and their implementation maturity is presented. Additionally, the capabilities of the reviewed tools to support co-simulation are evaluated. Furthermore, existing challenges are highlighted, and potential improvements are discussed.

An Educational Case Study of Using SysML and TTool for Unmanned Aerial Vehicles Design

This article shares an experience in using the systems modeling language (SysML) for the design and formal verification of unmanned aerial vehicles (UAVs). In particular, this article shows how our approach helps detecting early design errors. A UAV in charge of taking pictures serves as an educational and running example throughout this article. The SysML model of the UAV is simulated and formally verified using the free and open-source tool named TTool. This educational case study gives the authors of this article an opportunity to draw lessons from teaching SysML.

A Declarative Approach for Transforming SysML Models to Executable Simulation Models

Systems Modeling Language (SysML) is an object management group standard for systems-of-systems engineering. It enables the description of complex system models; however, it cannot effectively support all system engineering activities. For instance, system performance evaluation is usually performed via simulation. In this case, the transformation of SysML system models to executable simulation models for specific simulation methodologies and tools is required. Model transformation is a key component for addressing the challenges of seamless integration of SysML model simulation in model-based system engineering. In this paper, we explore a declarative approach, based on the query/view/transformation-relations (QVT-R) standard, for the transformation of SysML models to executable simulation models, fully adhering model-driven architecture (MDA) concepts. It is supported by a framework implemented to provide executable simulation model and code generation. Methodological guidelines, for the effective use of a declarative language as QVT-R, for model transformation, are provided, emphasizing the utilization of existing domain-specific SysML profiles, as well as executable simulation library components. The experience obtained from two different domains, namely, enterprise information and railway transportation systems, modeled as systems-of-systems via SysML, is discussed, based on a quantitative analysis of the respective QVT-R transformations.

A Model of a Wireless Factory Work-Cell Using the Systems Modeling Language.

Wireless technology is a key enabler of the vision of the future factory work-cell. Such a work-cell will operate autonomously with a high degree of mobility enabled by wireless technology. This paper describes the work-cell using the Systems Modeling Language (SysML). Using SysML the structural and parametric characteristics of the work-cell are described. Our model provides the architectural components and performance constraints of the work-cell in which wireless is used for a significant portion of connectivity. It identifies the structural components, interfaces, and data flows. Parametric characteristics that impact work-cell performance are included in the model. Using this model, industrial wireless networking requirements and work-cell behaviors may be developed and performance limits may be evaluated. The SysML model presented here is developed using MagicDraw 18.5 by No Magic.

SysML-based Profile for Dependable UAV Design

Model-based systems engineering approaches are commonly used for the development of various heterogeneous mechatronic systems including nowadays popular Unmanned Aerial Vehicles (UAV). As a rule, the dependability analysis is carried out during the system integration phase of the UAV development. Therefore, fundamental design drawbacks might be uncovered too late leading to serious and costly rework. This paper presents a new methodology for the early dependability analysis of a UAV system applicable during the design phase. The proposed dependability analysis is based on the Dual-graph Error Propagation Model (DEPM), a stochastic model of system design aspects that influence error propagation processes: control flow, data flow, and component-level reliability properties. A new domain-specific Systems Modeling Language (SysML) profile and the transformation algorithm from the SysML model to the DEPM are introduced as two key parts of this methodology as well as the main research results of this paper. The relevant technical details of the modeling workflow are demonstrated with a case study UAV that explains how to design a UAV using the introduced SysML profile, transform the SysML model into the DEPM, and evaluate dependability properties.

Model of Mobile Manipulator Performance Measurement using SysML.

Test methods for measuring safety and performance of mobile manipulators have yet to be developed. Therefore, potential mobile manipulator users cannot compare one system to another. Systems Modeling Language (SysML) is a general-purpose modeling language for systems engineering applications that supports the specification, analysis, design, verification, and validation of simple through complex systems, such as mobile manipulators. As test methods are developed to allow performance comparison of the varied mobile manipulators, so to should be the case of allowing comparison of most any mobile manipulator configuration and control strategy during performance measurements. Additionally, mobile manipulator manufacturers and users can then compare these systems to tasks using various methods. This paper uses SysML to describe two measurement methods (optical tracking and artifacts) and the performance measurement of mobile manipulators performing assembly tasks. The SysML models are verified through systems review, referenced experimentation and summarize with uncertainty propagation models of the mobile manipulator.

A Model‐Based Systems Engineering Application for Radiometric Measurement Uncertainty

AbstractThe current practice in radiometric measurement uncertainty of an instrument is to build the computational model in spreadsheets. Albeit easy to use, the spreadsheets are difficult for users to understand the computational structure hierarchy, and in traceability to the performance requirements. The motivation of this study is to overcome these weaknesses by transforming the spreadsheets to the Systems Modeling Language (SysML) model. The SysML model visually provides the structure hierarchy (using block definition diagrams) to the traditional spreadsheets and presents uncertainty calculations as mathematical constraints captured by parametric diagrams. In addition, the SysML requirement diagrams give requirement traceability to the uncertainty elements. The current model has been extended beyond the uncertainty analysis to include structure decomposition of the physical instrument as well as the total instrument mass analysis. A system‐level design trade analysis that encompasses both radiometric measurement uncertainty and system mass is demonstrated. The Desirability Function method is applied to optimally select the design, where both the uncertainty and mass are simultaneously considered.

Simulating simulation-agnostic SysML models for enterprise information systems via DEVS

Systems Modeling Language (SysML) is used as the modeling infrastructure in systems engineering, especially for complex systems design, independently of the system domain. Simulation is a common method to perform system model verification, during the systems development process. However, simulation code generation and execution is not integrated within the system design activity, as it is facilitated by SysML. It is either conducted as an external activity, after system design, or it affects the system design environment and practices, according to specific simulators requirements.This paper presents how existing, simulation-agnostic SysML models from the domain of Enterprise Information System (EISs), can be transformed to executable simulation code and in addition how the simulation results can be incorporated into the source SysML model through the exploitation of Model Driven Architecture (MDA) principles and techniques. To this end, several tools and technologies are utilized, while the verification process is triggered and finalized via the system modeling environment. Adoption of MDA provides a solid, high-level infrastructure and tool availability to the proposed approach.

A Reference System Architecture for the Energy–Water Nexus

The energy–water nexus has been studied predominantly through discussions of policy options supported by data surveys and technology considerations. As the degree of coupling between the energy and water systems is affected by the design and operation of various engineered system components, our understanding of the nexus and ability to tackle its associated challenges would be enhanced by a system-of-systems engineering model. Such a model, however, requires, first, the development of an appropriate system architecture that clearly identifies the relevant flows of matter and energy and the defining system parameters. This paper presents a reference system architecture for this purpose developed and presented with the Systems Modeling Language (SysML). Once instantiated, this architecture can serve three purposes. First, the presented graphical models can serve qualitative discussions on where and how the supply and demand of water and energy are interdependent. Second, within the operations timescale, the SysML models can support the development of automated information technology and control solutions that integrate energy and water management. Finally, at a planning timescale, the models can inform quantitative decisions on how to best grow and reconfigure the water, wastewater, and energy infrastructure.

Testing communication tasks in distributed control systems with SysML and Timed Colored Petri Nets model

Nowadays, Distributed Control Systems (DCSs) are commonly used and supersede stand-alone controllers in many industrial applications. Efficient communication is crucial for their proper operation. Unfortunately, there is a lack of appropriate methodologies and tools applicable to small- and medium-sized DCSs, especially for analysis and testing of communication tasks during early development stages. The paper proposes a flexible and efficient approach that fills this gap. It consists of the following steps. At the beginning, communication tasks and their parameters are specified using graphical diagrams from Systems Modeling Language (SysML). Then, the diagrams are used to automatically generate a model of communication subsystem in the Timed Colored Petri Nets (TCPNs) formalism. Finally, simulation of the TCPN model allows to estimate performance of a target system implementation and to predict its behavior in various cases. Thus, potential bottlenecks might be identified earlier and easier, as well as eliminated even before creation of a hardware prototype. The proposed approach has been introduced into the Control Program Developer (CPDev) engineering environment, which allows to program industrial controllers. Appropriate software tools, namely the editor for SysML communication model, the TCPN library with simulation engine, and the testing framework have been prepared.