Semantics of trace relations in requirements models for consistency checking and inferencing

Requirements traceability is the ability to relate requirements back to stakeholders and forward to corresponding design artifacts, code, and test cases. Although considerable research has been devoted to relating requirements in both forward and backward directions, less attention has been paid to relating requirements with other requirements. Relations between requirements influence a number of activities during software development such as consistency checking and change management. In most approaches and tools, there is a lack of precise definition of requirements relations. In this respect, deficient results may be produced. In this paper, we aim at formal definitions of the relation types in order to enable reasoning about requirements relations. We give a requirements metamodel with commonly used relation types. The semantics of the relations is provided with a formalization in first-order logic. We use the formalization for consistency checking of relations and for inferring new relations. A tool has been built to support both reasoning activities. We illustrate our approach in an example which shows that the formal semantics of relation types enables new relations to be inferred and contradicting relations in requirements documents to be determined. The application of requirements reasoning based on formal semantics resolves many of the deficiencies observed in other approaches. Our tool supports better understanding of dependencies between requirements

SysML for embedded automotive Systems: a practical approach

International audienceWhile SysML (System Modeling Language) is a leading topic for System Engineering (SE) in all domains, there is no pragmatic implementation of SE for automotive embedded systems and products. In this paper, a proposal is developed to meet the needs of Valeo product lines

Cost optimization in requirements management for space systems

2021 Spring.Includes bibliographical references.When producing complex space systems, the transformation of customer needs into a realized system includes the development of product requirements. The ability to generate and manage the requirements can either enable the overall system development or drive significant cost and schedule impacts. Assessing practices in the industry and publications, it is observed that there is a substantial amount of documented approaches to address requirement development and product verification, but only a limited amount of documented approaches for requirements management. A complex system can have tens of thousands of requirements across multiple levels of development which, if not well managed, can lead to hidden costs associated with missed requirements and product rework. With current space system projects being developed at a rapid pace using more cost constrained approaches such as fixed budgets, an investigation into more efficient processes, such as requirements management, can yield methods to enable successful, cost effective system development. To address the optimal approach of managing requirements for complex space systems, this dissertation assesses current practices for requirements management, evaluates various contributing factors towards optimization of project costs associated with this activity, and proposes an optimized requirements management process to utilize during the development of space systems. Four key areas of process control are identified for requirements management optimization on a project, including utilization of a data focused requirements management approach, development (and review) of requirements using a collaborative software application, ensuring the requirement set is a consolidated with an appropriate amount of requirements for the project, and evaluating when to officially levy requirements on the product developers based on requirement maturation stability. Multiple case studies are presented to evaluate if the proposed requirements management process yields improvement over traditional approaches, including a simulation of the current state and proposed requirements management approaches. Ultimately, usage of the proposed optimized set of processes is demonstrated to be a cost effective approach when compared against traditional processes that may adversely impact the development of new space systems

Model-Based Systems Engineering Pilot Program at NASA Langley

NASA Langley Research Center conducted a pilot program to evaluate the benefits of using a Model-Based Systems Engineering (MBSE) approach during the early phase of the Materials International Space Station Experiment-X (MISSE-X) project. The goal of the pilot was to leverage MBSE tools and methods, including the Systems Modeling Language (SysML), to understand the net gain of utilizing this approach on a moderate size flight project. The System Requirements Review (SRR) success criteria were used to guide the work products desired from the pilot. This paper discusses the pilot project implementation, provides SysML model examples, identifies lessons learned, and describes plans for further use on MBSE on MISSE-X

Integrating models and simulations of continuous dynamic system behavior into SysML

Contemporary systems engineering problems are becoming increasingly complex as they are handled by geographically distributed design teams, constrained by the objectives of multiple stakeholders, and inundated by large quantities of design information. According to the principles of model-based systems engineering (MBSE), engineers can effectively manage increasing complexity by replacing document-centric design methods with computerized, model-based approaches. In this thesis, modeling constructs from SysML and Modelica are integrated to improve support for MBSE. The Object Management Group has recently developed the Systems Modeling Language (OMG SysML ) to provide a comprehensive set constructs for modeling many common aspects of systems engineering problems (e.g. system requirements, structures, functions). Complementing these SysML constructs, the Modelica language has emerged as a standard for modeling the continuous dynamics (CD) of systems in terms of hybrid discrete- event and differential algebraic equation systems. The integration of SysML and Modelica is explored from three different perspectives: the definition of CD models in SysML; the use of graph transformations to automate the transformation of SysML CD models into Modelica models; and the integration of CD models and other SysML models (e.g. structural, requirements) through the depiction of simulation experiments and engineering analyses. Throughout the thesis, example models of a car suspension and a hydraulically-powered excavator are used for demonstration. The core result of this work is the provision of modeling abilities that do not exist independently in SysML or Modelica. These abilities allow systems engineers to prescribe necessary system analyses and relate them to stakeholder concerns and other system aspects. Moreover, this work provides a basis for model integration which can be generalized and re-specialized for integrating other modeling formalisms into SysML.M.S.Committee Chair: Chris Paredis; Committee Member: Dirk Schaefer; Committee Member: Russell Pea

Enabling Assurance in the MBSE Environment

A number of specific benefits that fit within the hallmarks of effective development are realized with implementation of model-based approaches to systems and assurance. Model Based Systems Engineering (MBSE) enabled by standardized modeling languages (e.g., SysML) is at the core. These benefits in the context of spaceflight system challenges can include: Improved management of complex development, Reduced risk in the development process, Improved cost management, Improved design decisions. With appropriate modeling techniques the assurance community can improve early oversight and insight into project development. NASA has shown the basic constructs of SysML in an MBSE environment offer several key advantages, within a Model Based Mission Assurance (MBMA) initiative

Exploring the potentials and tools of systems engineering and MBSE in machine design

Abstract. This thesis explores Systems Engineering (SE) and Model-Based Systems Engineering (MBSE) in the context of modern machine design. The primary objective is to understand how SE’s interdisciplinary and holistic methodologies, once rooted in the telephone industry, can be seamlessly adapted into the intricate realm of machine design. One of the key findings suggests that, despite the growing intrigue around MBSE as a novel approach to systems engineering, there is still a lack of concrete evidence to substantiate its effectiveness. However, certain studies have highlighted the strengths of MBSE, especially its tools’ capability for parametric and numerical analyses. These tools integrate smoothly with the initial phases of the design process, enabling continuous exploration of a system’s dynamic behavior. While MBSE is still emerging, it offers several apparent advantages, such as improved communication, increased consistency, and efficient use of both time and financial resources. With the knowledge that mechanical engineering these days means working with many different specialists from various fields, we can safely say that engineering machines like cars and planes fall into the realm of systems engineering. The primary methodology employed for data acquisition in this thesis was a literature review.Systeemitekniikan ja MBSE:n mahdollisuudet ja työkalut koneensuunnittelussa. Tiivistelmä. Tämä opinnäytetyö tutkii Systeemitekniikan (SE) ja Mallipohjaisen Systeemitekniikan (MBSE) käsitteitä modernin koneensuunnittelun kontekstissa. Pääasiallinen tavoite on ymmärtää, miten SE:n monitieteelliset ja kokonaisvaltaiset menetelmät, jotka alun perin juontavat juurensa puhelinalaan, voivat saumattomasti soveltua monimutkaisen koneensuunnittelun maailmaan. Yksi keskeisistä havainnoista viittaa siihen, että vaikka MBSE herättää kasvavaa kiinnostusta uutena lähestymistapana systeemitekniikkaan, sen tehokkuutta tukevasta konkreettisesta näytöstä on edelleen niukasti saatavilla. Kuitenkin tietyt tutkimukset ovat korostaneet MBSE:n vahvuuksia, erityisesti sen työkalujen kykyä parametriseen ja numeeriseen analyysiin. Nämä työkalut integroituvat saumattomasti suunnitteluprosessin alkuvaiheisiin, mahdollistaen järjestelmän dynaamisen käyttäytymisen jatkuvan tutkimisen. Vaikka MBSE on edelleen kehittyvä alue, se tarjoaa useita selkeitä etuja, kuten parannetun kommunikaation, lisääntyneen johdonmukaisuuden sekä ajan ja taloudellisten resurssien tehokkaamman hyödyntämisen. Kun otetaan huomioon, että nykyaikainen koneensuunnittelu edellyttää usein yhteistyötä eri alojen erikoisasiantuntijoiden kanssa, voidaan perustellusti väittää, että monimutkaisten koneiden, kuten autojen ja lentokoneiden, suunnittelu kuuluu systeemitekniikan piiriin. Tämän opinnäytetyön tärkein tutkimusmenetelmä oli kirjallisuuskatsaus

Model-Based Systems Engineering for System Safety: An Introduction

Model-based systems engineering (MBSE) has gained momentum as the predominant method of analyzing and deriving system requirements, as well as of verifying and validating system performance. Over the years, several frameworks have gained prominence as approved methods and formal techniques to model systems. MBSE technology continues to gain popularity within the systems engineering domain, especially in markets of complex systems. To remain relevant within the context of concurrent engineering, it is advantageous for system safety engineers to learn how these techniques are affecting system design so that safety is addressed within system development. This paper provides an overview of MBSE in theory and practice, and provides high-level details on how the system safety engineer can use these methods for optimum impact in affecting safety design

Development of New Model-based Methods in ASIC Requirements Engineering

Requirements in the development of application-specific integrated circuits (ASICs) continue to increase. This leads to more complexities in handling and processing the requirements, which often causes inconsistencies in the requirments. To better manage the resulting complexities, ASIC development is evolving into a model-based process. This thesis is part of a continuing research into the application and evolution of a model-based process for ASIC development at the Robert Bosch GmbH. It focuses on providing methologies that enable tracing of ASIC requirements and specifications as part of a model-based development process to eliminate inconsistencies in the requirements. The question of what requirements are and, what their traceability means, is defined and analysed in the context of their relationships to models. This thesis applies requirements engineering (RE) practices to the processing of ASIC requirements in a development environment. This environment is defined by availability of tools which are compliant with some standards and technologies. Relying on semi-formal interviews to understand the process in this environment and what stakeholders expect, this thesis applies the standards and technologies with which these tools are compliant to provide methodologies that ensures requirements traceability. Effective traceability methods were proven to be matrices and tables, but for cases of fewer requirements (ten or below), requirement diagrams are also efficient and effective. Furthermore, the development process as a collaborative effort was shown to be enhanced by using the resulting tool-chain, when the defined methodologies are properly followed. This solution was tested on an ASIC concept development project as a case study

Model-Based Systems Engineering for a Small-Lift Launch Facility

A study of model‐based systems engineering (MBSE) applied to a small‐lift launch facility is presented. The research uses Systems Modeling Language (SysML) products and functional diagrams to document the ground systems on a launch pad servicing a small class payload (0–2 tons). With the projected growth in launch cadence of small‐lift rockets in the coming decade, there is a need to design increasingly complex launch systems with greater efficiency. The potential improvements in project communication, quality, and productivity are explored by developing a model following the ISO/IEC 15288 technical process framework and the International Council on Systems Engineering (INCOSE) Object‐Oriented Systems Engineering Method (OOSEM) methodology. The stakeholder requirements are defined and analyzed to provide traceability to individual systems and subsystems. An architecture is proposed by generating engineering artifacts such as piping and instrumentation drawings. The concepts are verified and validated by performing engineering trade studies concentrated on the pneumatic and fuel subsystems