A Product Line Systems Engineering Process for Variability Identification and Reduction

Software Product Line Engineering has attracted attention in the last two decades due to its promising capabilities to reduce costs and time to market through reuse of requirements and components. In practice, developing system level product lines in a large-scale company is not an easy task as there may be thousands of variants and multiple disciplines involved. The manual reuse of legacy system models at domain engineering to build reusable system libraries and configurations of variants to derive target products can be infeasible. To tackle this challenge, a Product Line Systems Engineering process is proposed. Specifically, the process extends research in the System Orthogonal Variability Model to support hierarchical variability modeling with formal definitions; utilizes Systems Engineering concepts and legacy system models to build the hierarchy for the variability model and to identify essential relations between variants; and finally, analyzes the identified relations to reduce the number of variation points. The process, which is automated by computational algorithms, is demonstrated through an illustrative example on generalized Rolls-Royce aircraft engine control systems. To evaluate the effectiveness of the process in the reduction of variation points, it is further applied to case studies in different engineering domains at different levels of complexity. Subject to system model availability, reduction of 14% to 40% in the number of variation points are demonstrated in the case studies.Comment: 12 pages, 6 figures, 2 tables; submitted to the IEEE Systems Journal on 3rd June 201

Reliability Analysis of Complex NASA Systems with Model-Based Engineering

The emergence of model-based engineering, with Model- Based Systems Engineering (MBSE) leading the way, is transforming design and analysis methodologies. The recognized benefits to systems development include moving from document-centric information systems and document-centric project communication to a model-centric environment in which control of design changes in the life cycles is facilitated. In addition, a single source of truth about the system, that is up-to-date in all respects of the design, becomes the authoritative source of data and information about the system. This promotes consistency and efficiency in regard to integration of the system elements as the design emerges and thereby may further optimize the design. Therefore Reliability Engineers (REs) supporting NASA missions must be integrated into model-based engineering to ensure the outputs of their analyses are relevant and value-needed to the design, development, and operational processes for failure risks assessment and communication

Clafer: Lightweight Modeling of Structure, Behaviour, and Variability

Embedded software is growing fast in size and complexity, leading to intimate mixture of complex architectures and complex control. Consequently, software specification requires modeling both structures and behaviour of systems. Unfortunately, existing languages do not integrate these aspects well, usually prioritizing one of them. It is common to develop a separate language for each of these facets. In this paper, we contribute Clafer: a small language that attempts to tackle this challenge. It combines rich structural modeling with state of the art behavioural formalisms. We are not aware of any other modeling language that seamlessly combines these facets common to system and software modeling. We show how Clafer, in a single unified syntax and semantics, allows capturing feature models (variability), component models, discrete control models (automata) and variability encompassing all these aspects. The language is built on top of first order logic with quantifiers over basic entities (for modeling structures) combined with linear temporal logic (for modeling behaviour). On top of this semantic foundation we build a simple but expressive syntax, enriched with carefully selected syntactic expansions that cover hierarchical modeling, associations, automata, scenarios, and Dwyer's property patterns. We evaluate Clafer using a power window case study, and comparing it against other notations that substantially overlap with its scope (SysML, AADL, Temporal OCL and Live Sequence Charts), discussing benefits and perils of using a single notation for the purpose

Testing And Verification For The Open Source Release Of The Horizon Simulation Framework

Modeling and simulation tools are exceptionally useful for designing aerospace systems because they allow engineers to test and iterate designs before committing the massive resources required for system realization. The Horizon Simulation Framework (HSF) is a time-driven modeling and simulation tool which attempts to optimize how a modeled system could perform a mission profile. After 15 years of development, the HSF team aims to achieve a wider user and developer base by releasing the software open source. To ensure a successful release, the software required extensive testing, and the main scheduling algorithm required protections against new code breaking old functionality. The goal of the work presented in this thesis is to satisfy these requirements and officially release the software open source. The software was tested with \u3e 80% coverage and a continuous integration pipeline which runs build and unit/integration tests on every new commit was set up. Finally, supporting documentation and user resources were created and organized to promote community adoption of the software, making Horizon ready for an open source release

SysML Output Interface and System-Level Requirement Analyzer for the Horizon Simulation Framework

Model-Based Systems Engineering in industry has been constantly increasing its presence within the aerospace industry. SysML is one such MBSE tool that shows complex system organization and relationships. The Horizon Simulation Framework is another MBSE tool, created by Cal Poly students, that gives users the ability to run “day-in-the-life” simulations of systems. Finding a way to link these two tools could allow systems engineers to reap the benefits of both. This thesis investigates the background and design process involved with developing the code that can convert an output file generated in SysML, into a format specifically made for the Horizon Simulation Framework. The goal was to create an interface that can allow users to model a system in SysML, and analyze the model and verify system requirements using HSF. Another goal was to expand the capabilities of the Horizon Simulation Framework by designing and develop a module that would allow users to define and analyze system-level requirements. To evaluate the effectiveness of both codes, the Aeolus example case was used. A SysML model of the system was created as the product of another thesis; SysML based CubeSat Model Design and Integration with the Horizon Simulation Framework. The Aeolus SysML model was converted and used as input in an HSF simulation. The SysML model simulation data was compared against those of the original test case. To test the requirement module, system level requirements were formulated within the Aeolus system and run in simulation, providing an analysis of the results. The results of the analysis confirmed a successful conversion of the SysML model into an equivalent HSF model and a successful analysis of system-level requirements

A Concept Model To Analyze The Digitalization Of Industrial Fire Protection Systems Decision-Making

As a result of technological advances during the 21st century and the rise of digitalization, optimized and robust decision-making in selecting industrial fire protection systems can be increasingly feasible. This paper proposes a concept model to analyze the digitalization of industrial fire protection systems decision-making solution to minimize the efforts in deciding the most viable fire protection system for a wide range of industrial applications. A survey including targeted and generic questions (like the sample questions in Appendix A) is developed and used to collect data on existing fire protection systems and their performance during emergencies in various industries. The survey also collects data on fire risks in selected installations. Then the data is decomposed and translated into object-oriented models using Model-Based Systems Engineering (MBSE) methods and Systems Modelling Language (SysML) tool. The collection of these generic digital models, which are known as a pattern library, is then used to generate detailed fire protection systems logical architectures. The individual elements, or “Blocks”, on the models provide coherent properties like fire risk, time, installation cost, maintenance cost, types of suppression systems, level of automation, types of detection systems, etc. The demand and requirements for the new optimized fire protection system are then translated into a Pugh Matrix with a weighted average analysis and applied to the “block” properties, thus generating a solution for the system's logical architecture and second novel pattern library application

Design-time detection of physical-unit changes in product lines

Software product lines evolve over time, both as new products are added to the product line and as existing products are updated. This evolution creates unintended as well as planned changes to Systems. A persistent problem is that unintended changes are hard to detect. Often they are not discovered until testing or operations. Late discovery is a problem especially in safety-critical, cyberphysical product lines such as avionics, pacemakers, and smart-braking systems, where unintended changes may lead to accidents. This thesis proposes an approach and a prototype tool to detect unintended changes earlier in development of a new product in the product line. The capability to detect potentially risky, unintended changes at the design stage is beneficial because repair is easier, less costly, and safer in design than when detection is delayed to testing or operations. The Product Line Change Detector (PLCD) introduced here analyzes products’ SysML block and parametric diagrams, which are typical project artifacts for cyber-physical systems, in order to detect problematic, unintended changes. The PLCD software automatically detects potential change-related issues, ranks them in terms of severity using the products’ safety-analysis artifacts, and reports them to developers in a graphical format. Developers select and fix the reported issues with the assistance of the tool’s displays, with the tool recording the fixes and updating the SysML diagrams accordingly. The evaluation of PLCD’s performance and capabilities uses three product lines, extended from cyber-physical systems in the literature: NASA astronaut jetpack, vehicle dynamics, and low-earth satellite. The evaluation focuses on unintended changes that cause physical unit inconsistencies, such as between meters and feet, since those may lead to accidents in cyber-physical product lines. The evaluation results show that PLCD successfully detects such unintended changes both in a single product and between products in a software product line

Model Based System Engineering for the development of System on Chip

Abstract. Model Based System Engineering (MBSE) has been utilized in auto manufacturing industries, airplane manufacturing and maintenance, and factory process automation industries. These are some of the complex fields. As SoC design is a complex process and requires years of work, MBSE can reduce time, complexity, reuse, and maintenance costs. It seems a fruitful idea/decision to take MBSE into use in SoC design depending on the previously mentioned elements. System on Chip (SoC) is obtaining the interest of many big companies. Therefore, MBSE will represent a huge competitive advantage once it is taken fully into the systems engineering roles of SoC. The existence of geographically dispersed teams, complexity of systems, interdisciplinarity, personalized system description, and their integration can be enabled by MBSE. As an emerging paradigm for the systems of the 21st century, MBSE paved the way for creating successful systems (for the companies) that are end to end connected. This research focuses on making use of MBSE in SoC. The thesis will show how SoC processes can be implemented in one complete model with top to bottom approach. Firstly, the traditional systems engineering approach has been explained with its tools and examples. Secondly, the need for taking up MBSE by the systems engineers is expressed. This contains the applications, use in modern systems, and benefits of MBSE. Moreover, MBSE methodology tools, languages, and their use in SoC is illustrated with examples. As SoC development is a huge and complex process; therefore, a small component of the chip has been taken in consideration for the purpose of understanding and making of the thesis. MBSE is a model-based approach hence a language needs to be present to produce these models and that language is SysML and OPD/OPL. SysML language and MagicDraw tool is used for expressing the architecture of the system. MagicDraw supports several external evaluators for evaluation of expressions and MATLAB is one of them. With MagicDraw we can do simulations, input parameters, and analyze data by processing on it using algorithms developed in MATLAB

Evolution of Model-Based System Engineering Methodologies for the Design of Space Systems in the Advanced Stages of the Project (Phases B-C)

The main topic of the present work is addressed to the evaluation of the possible improvements that can be achieved with the integration of Model Based System Engineering Methodologies in the advanced phases of space project. In particular a model based approach will be proposed for two main aspects directly affecting the design phases of complex systems. The first one is represented by the management of design options that becomes difficult to monitor as the project proceeds, increasing the amount of data to take into consideration. The other one is represented by the integration between Multidisciplinary Design Optimization (MDO) techniques and a Model Based System Engineering (MBSE) environment. The aim of the research activity concerns the feasibility of such connection in order to assess actual advantages and possible drawbacks. In this last case the objective is to show how the Multidisciplinary Design Optimization (MDO) methods may be managed in the context of a MBSE environment with respect to the traditional design approach. In particular this analysis is addressed to the demonstration of the benefits of MBSE methodology and MDO techniques considering a space system reference case. In the first part of the thesis a briefly description of the problem statement is introduced to better explain the subjects of the following chapters. In particular the reasons and the related purposes that have animated this work are considered. In the next sec..on the state of the art about the considered approach is presented, providing a background for the following activities. In this context a wider analysis of the motivations and thesis objectives is considered. The following chapters deals with the survey and critical assessment of the main work related to this thesis. The analysis, design and implementation of the proposed framework are considered in the next sections. At the end of this part the results obtained are presented without arguing about the related benefits or drawbacks, which are considered in the following. A critical assessment of the results is then presented, analyzing the main contributions and related disadvantages with respect to the current approaches. In the next sec..on the incoming activities and further developments are presented. The final part concerns at last the summary conclusions of the work done

Model-Based Systems Engineering in Concurrent Engineering Centers

Concurrent Engineering Centers (CECs) are specialized facilities with a goal of generating and maturing engineering designs by enabling rapid design iterations. This is accomplished by co-locating a team of experts (either physically or virtually) in a room with a focused design goal and a limited timeline of a week or less. The systems engineer uses a model of the system to capture the relevant interfaces and manage the overall architecture. A single model that integrates other design information and modeling allows the entire team to visualize the concurrent activity and identify conflicts more efficiently, potentially resulting in a systems model that will continue to be used throughout the project lifecycle. Performing systems engineering using such a system model is the definition of model-based systems engineering (MBSE); therefore, CECs evolving their approach to incorporate advances in MBSE are more successful in reducing time and cost needed to meet study goals. This paper surveys space mission CECs that are in the middle of this evolution, and the authors share their experiences in order to promote discussion within the community