349 research outputs found

    Model Based Mission Assurance: NASA's Assurance Future

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    Model Based Systems Engineering (MBSE) is seeing increased application in planning and design of NASAs missions. This suggests the question: what will be the corresponding practice of Model Based Mission Assurance (MBMA)? Contemporaneously, NASAs Office of Safety and Mission Assurance (OSMA) is evaluating a new objectives based approach to standards to ensure that the Safety and Mission Assurance disciplines and programs are addressing the challenges of NASAs changing missions, acquisition and engineering practices, and technology. MBSE is a prominent example of a changing engineering practice. We use NASAs objectives-based strategy for Reliability and Maintainability as a means to examine how MBSE will affect assurance. We surveyed MBSE literature to look specifically for these affects, and find a variety of them discussed (some are anticipated, some are reported from applications to date). Predominantly these apply to the early stages of design, although there are also extrapolations of how MBSE practices will have benefits for testing phases. As the effort to develop MBMA continues, it will need to clearly and unambiguously establish the roles of uncertainty and risk in the system model. This will enable a variety of uncertainty-based analyses to be performed much more rapidly than ever before and has the promise to increase the integration of CRM (Continuous Risk Management) and PRA (Probabilistic Risk Analyses) even more fully into the project development life cycle. Various views and viewpoints will be required for assurance disciplines, and an over-arching viewpoint will then be able to more completely characterize the state of the project/program as well as (possibly) enabling the safety case approach for overall risk awareness and communication

    Contracts and Behavioral Patterns for SoS: The EU IP DANSE approach

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    This paper presents some of the results of the first year of DANSE, one of the first EU IP projects dedicated to SoS. Concretely, we offer a tool chain that allows to specify SoS and SoS requirements at high level, and analyse them using powerful toolsets coming from the formal verification area. At the high level, we use UPDM, the system model provided by the british army as well as a new type of contract based on behavioral patterns. At low level, we rely on a powerful simulation toolset combined with recent advances from the area of statistical model checking. The approach has been applied to a case study developed at EADS Innovation Works.Comment: In Proceedings AiSoS 2013, arXiv:1311.319

    A Security Verification Framework for SysML Activity Diagrams

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    UML and SysML play a central role in modern software and systems engineering. They are considered as the de facto standard for modeling software and systems. Today’s systems are created from a myriad of interacting parts that are combined to produce visible behavior. The main difficulty arises from the different ways in modeling each component and the way they interact with each other. Moreover, nowadays secure software has become an essential part in industrial development. One challenge in academia as well as in industry is to produce a secure product. Another challenge is to prove its correctness especially when the software environment is imprecise and uncertain. The aim of this thesis is to provide a practical and formal framework that enables security risk assessment and security requirements verification on a system modeled as a composition of UML/SysML behavioral diagrams. Our main contribution is a novel approach to automatically verify security of systems on their design models based on security requirements, probabilistic adversarial interactions between potential attackers and the system’s models. These structures are shaped to provide an elegant way to define the combination between different kinds of diagrams. We rely on stochastic security templates to specify security properties and a standard catalogue of attack patterns to build a library of attacks design patterns. The result of the interaction between selected attack scenarios and the composed diagrams with the instantiated security properties are used to quantify security risk by applying probabilistic model-checker. To handle the verification process scalability, our approach allows the verification of large system efficiently by optimizing and avoiding the global model construction. To demonstrate the effectiveness of our approach, we apply our methodology on academia as well as industrial benchmarks

    Model Based Mission Assurance in a Model Based Systems Engineering (MBSE) Framework: State-of-the-Art Assessment

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    This report explores the current state of the art of Safety and Mission Assurance (S&MA) in projects that have shifted towards Model Based Systems Engineering (MBSE). Its goal is to provide insight into how NASA's Office of Safety and Mission Assurance (OSMA) should respond to this shift. In MBSE, systems engineering information is organized and represented in models: rigorous computer-based representations, which collectively make many activities easier to perform, less error prone, and scalable. S&MA practices must shift accordingly. The "Objective Structure Hierarchies" recently developed by OSMA provide the framework for understanding this shift. Although the objectives themselves will remain constant, S&MA practices (activities, processes, tools) to achieve them are subject to change. This report presents insights derived from literature studies and interviews. The literature studies gleaned assurance implications from reports of space-related applications of MBSE. The interviews with knowledgeable S&MA and MBSE personnel discovered concerns and ideas for how assurance may adapt. Preliminary findings and observations are presented on the state of practice of S&MA with respect to MBSE, how it is already changing, and how it is likely to change further. Finally, recommendations are provided on how to foster the evolution of S&MA to best fit with MBSE

    Verification and validation of UML and SysML based systems engineering design models

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    In this thesis, we address the issue of model-based verification and validation of systems engineering design models expressed using UML/SysML. The main objectives are to assess the design from its structural and behavioral perspectives and to enable a qualitative as well as a quantitative appraisal of its conformance with respect to its requirements and a set of desired properties. To this end, we elaborate a heretofore unattempted unified approach composed of three well-established techniques that are model-checking, static analysis, and software engineering metrics. These techniques are synergistically combined so that they yield a comprehensive and enhanced assessment. Furthermore, we propose to extend this approach with performance analysis and probabilistic assessment of SysML activity diagrams. Thus, we devise an algorithm that systematically maps these diagrams into their corresponding probabilistic models encoded using the specification language of the probabilistic symbolic model-checker PRISM. Moreover, we define a first of its kind probabilistic calculus, namely activity calculus, dedicated to capture the essence of SysML activity diagrams and its underlying operational semantics in terms of Markov decision processes. Furthermore, we propose a formal syntax and operational semantics for the input language of PRISM. Finally, we mathematically prove the soundness of our translation algorithm with respect to the devised operational semantics using a simulation preorder defined upon Markov decision processes

    Model to code generation of UML/SysML activity diagrams for ARM CortexM MCUs

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    The complexity in embedded systems has been increased in the last years. To overcome the system complexity various methodologies have been presented. Both in industry and academia, Model-Based design has been accepted to be the best solution to solve this problem. Model-Based Design is a technique for developing embedded system applications and cyber-physical systems based on a hierarchy of reusable design blocks. SysML/UML activity diagrams are widely used for the modelling and analysis of complex systems, and they have become the de facto standard for software and embedded systems. Previously in our group, we formalized SysML activity diagrams by developing a calculus called New Activity Calculus (NuAC). In this work, we redefined NuAC terms to support RTX (Keil Real-Time Operating System) and present an automated SysML/UML activity diagram to RTX code generator, using mapping rules expressed in NuAC. To achieve this goal, we proposed a set of mapping rules that were used in mapping a SysML/ UML activity diagram into a suitable code to be executed on ARM CortexM processor family. To automate the process of code generation, we presented a JAVA application that uses the proposed rules to automatically generate the RTX code from the input activity diagram model. To demonstrate the capability of the developed tool, we use it to implement a train control algorithm on an ARM Cortex-M4 device. The implemented model is run on the target platform and the correct functionality of the system is verified

    Methodology for automated Petri Net model generation to support Reliability Modelling

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    As the complexity of engineering systems and processes increases, determining their optimal performance also becomes increasingly complex. There are various reliability methods available to model performance but generating the models can become a significant task that is cumbersome, error-prone and tedious. Hence, over the years, work has been undertaken into automatically generating reliability models in order to detect the most critical components and design errors at an early stage, supporting alternative designs. Earlier work lacks full automation resulting in semi-automated methods since they require user intervention to import system information to the algorithm, focus on specific domains and cannot accurately model systems or processes with control loops and dynamic features. This thesis develops a novel method that can generate reliability models for complex systems and processes, based on Petri Net models. The process has been fully automated with software developed that extracts the information required for the model from a topology diagram that describes the system or process considered and generates the corresponding mathematical and graphical representations of the Petri Net model. Such topology diagrams are used in industrial sectors, ranging from aerospace and automotive engineering to finance, defence, government, entertainment and telecommunications. Complex real-life scenarios are studied to demonstrate the application of the proposed method, followed by the verification, validation and simulation of the developed Petri Net models. Thus, the proposed method is seen to be a powerful tool to automatically obtain the PN modelling formalism from a topology diagram, commonly used in industry, by: - Handling and efficiently modelling systems and processes with a large number of components and activities respectively, dependent events and control loops. - Providing generic domain applicability. - Providing software independence by generating models readily understandable by the user without requiring further manipulation by any industrial software. Finally, the method documented in this thesis enables engineers to conduct reliability and performance analysis in a timely manner that ensures the results feed into the design process

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

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    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

    Uncertainty representation in software models: a survey

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    This paper provides a comprehensive overview and analysis of research work on how uncertainty is currently represented in software models. The survey presents the definitions and current research status of different proposals for addressing uncertainty modeling and introduces a classification framework that allows to compare and classify existing proposals, analyze their current status and identify new trends. In addition, we discuss possible future research directions, opportunities and challenges.This work is partially supported by the European Commission (FEDER) and the Spanish Government under projects APOLO (US1264651), HORATIO (RTI2018-101204-B-C21), EKIPMENT-PLUS (P18-FR-2895) and COSCA (PGC2018-094905-B-I00)
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