Safe and Reliable Metro Platform Screen Doors Control/Command Systems

This book is a practical guide for the development and qualification of safety-critical systems, standards compliance, and use of formal methods and tools.

In the development of safety-critical system, ModelBased Safety Assessment (MBSA) process can reduce the development complexity and improve assessment efficiency. As an important part of MBSA, system modeling and safety requirements description with formal methods still lack a well-defined process. In this paper, the relationship between traditional safety assessment process and MBSA is discussed, a system modeling and safety property formalization method based on NuSMV is proposed. Finally, a case study is presented to demonstrate and validate the proposed modeling method.

Basically, aircraft engines can be divided into a control embedded system and a controlled system with its environment. The behaviour of the controlled system is given a priori, while the control system still needs to be designed in a way guaranteeing the correct overall behaviour under all operational conditions depending on the flight domain. A large quantity of functions in control systems can be described by a formal system expressed in block diagrams and state-based representations. These representations can be translated to formal based tools relying on the synchronous languages Signal and Statecharts. SACRES is a tool set supporting the design of safety-critical embedded control systems. It integrates the tools and specification techniques Statemate, Sildex, and Timing Diagrams with tool components for automatic code generation, formal verification based on model checking techniques, and an innovative approach for automatic code validation for target code generated from DC+. Technical achievements are The main benefits of the SACRES approach are reduced risks for design errors and decreased design times and costs for the development of dependable (safety critical) embedded systems. SACRES is an attempt to avoid unpredictability (particularly that arising from late feedback from testing) associated with development of safety critical systems, through the use of the maximum degree of automation, especially in respect of code generation and verification. An outstanding property of SACRES is the combination of specification styles and specification tools being applied in practice with automatic tools to establish provable correctness with respect to required properties. Both dependability and productivity are increased by automatic code generation from high-level specifications such that the generated code can be validated against higher levels by rigorous proofs. These techniques allow traditional tests by sampling to be replaced by rigorous checking techniques which correspond to 100% coverage of test cases. In order to address a global innovative approach in the near future which match the whole software configuration, the SACRES tool set should be interfaced with asynchronous techniques matching the operating system development. This raises an open question in the software development future new process.

This paper provides a novel method of identifying a set of design faults in Simulink\TargetLink models and production code generation well before generating the test cases. These models can be used for development of safety critical systems. We have developed stand-alone application which transforms TargetLink model to EA compatible UML (Unified Modeling Language) model represented as packages and composite structure diagrams. The entire process makes use of dSPACE and MathWorks tools.

Context. Development of safety-critical systems is mostly governed by process-heavy paradigms, while increasing demands on flexibility and agility also reach this domain. Objectives. We wanted to explore in more detail the industrial needs and challenges when facing this trend. Method. We launched a qualitative survey, interviewing engineers from four companies in four different industry domains. Results. The survey identifies human factors (skills, experience, and attitudes) being key in safety-critical systems development, as well as good documentation. Certification cost is related to change frequency, which is limiting flexibility. Component reuse and iterative processes were found to increase adaptability to changing customer needs. Conclusions. We conclude that agile development and flexibility may co-exist with safety-critical software development, although there are specific challenges to address.

In recent years, the UK Health and Safety Executive, the Institution of Electrical Engineers and the British Computer Society have collaborated in the management of a project to produce a set of competencies for engineers working in the sensitive area of safety-critical or safety-related systems. The resulting document owed much to the existence of the international standard IEC 61508. The development of competency descriptors for those involved in the design and development of safety-critical systems has led to some consideration of the properties of these competencies and to principles that may be applied in a more general setting. This article aims to capture these thoughts.

Safety assurance and certification are amongst the most expensive and time-consuming tasks in the development of safety-critical systems. The increasing complexity and size of these systems combined with their growing market demand requires the industry to implement a coherent reuse strategy. A key difficulty appears when trying to reuse products from one application domain in another, because different domains are subject to different safety regulations. Subsequently, for a reused product, the full safety assurance and certification process has to be applied, just as for a new product. This reduces the return on investment of such reuse. Further, market trends strongly suggest that many future safety-critical systems will be comprised of heterogeneous, dynamic coalitions of systems of systems. For this type of systems, it is crucial to develop sound strategies that would allow safety assurance and certification to be done compositionally.

Verification of safety requirements is one important task during the development of safety critical systems. The increasing complexity of systems makes manual analysis almost impossible. This paper introduces a new methodology for formal verification of technical systems with smartIflow (State Machines for Automation of Reliability-related Tasks using Information FLOWs). smartIflow is a new modeling language that has been especially designed for the purpose of automating the safety analysis process in early product life cycle stages. It builds up on experience with existing approaches. As is common practice in current approaches, components are modeled as finite state machines. However, new concepts are introduced to describe component interactions. Events play a major role for internal interactions between components as well as for external (user) interactions. Our approach to the verification of formally specified safety requirements is a two-step method. First, an exhaustive simulation creates knowledge about a great variety of possible behaviors of the system, especially including reactions on suddenly occurring (possibly intermittent) faults. In the second step, safety requirements specified in CTL (Computation Tree Logic) are verified using model checking techniques, and counterexamples are generated if these are not satisfied. The practical applicability of this approach is demonstrated based on a Java implementation using a simple Two-Tank-Pump-Consumer system.

Software reviews are one of the most efficient quality assurance techniques in software engineering. They are required for the enhancement of the software quality in early phases of the development process and often used in development of safety critical systems. In the field of software engineering for Air Traffic Management (ATM) the standard DO-278/ED-109 requires the rigorous application of code reviews and fully traceable reporting of the results. This case study presents a process and an IDE-integrated tool that complies with the requirements of the standard.

Reliability study of complex physical systems using SysML

Software Product Line Engineering (SPLE) is a software development paradigm that aims at reducing the development effort and shorting time-to-market through systematic software reuse. While this paradigm has been successfully applied for the development of embedded systems in various domains, new challenges have emerged from the development of safety critical systems that require certification against a specific standard. Existing SPLE approaches do not explicitly consider the various certification standards or levels that products should satisfy. In this paper, we focus on several practical issues involved in the SPLE process, establishing an infrastructure of a product line engineering for certified products. A metamodel is proposed to capture the entities involved in SPL certification and the relationships among them. ProLiCES, which is a model-driven process for the development of SPLs, was modified to serve as an example of our approach, in the context of the UAV (Unmanned Aerial Vehicle) domain.

Software engineering has devised several project management metrics to optimize implementation and obtain a product with high efficiency, at less time and cost. Inventors faced many challenges to find measurements that able to anticipate accurate results that help avoid errors and risks in the advanced stages of the project. The systems most affected by any errors during the development process are Safety-Critical systems (SCS), as 60% of failures during operation are due to errors during development. This paper proposes a metric that uses weight and milestones to predict implementation in advanced stages of a project. The proposed metric is called Weighted Test Metric (WTM). WTM enhance the reliability assessment and reduce failures during project development by predicting Standards Achievement (SA) in the next test. WTM results showed that faults can be reduced during the development of a petroleum drilling project to 0.67% and enhance the overall reliability to 99.16% while actual results (98.30%). This paper focuses on “How to enhance reliability assessment and reduce failures during project development activities?”. This research raises the question through the application of WTM in the stages of development of the Petroleum Drilling Project.KeywordsSafety-Critical System (SCS)Safety-Critical System Development (SCSD)Area: software project management metricsDevelopment metrics

IEC 61508 is widely viewed as the best available international generic standard for the management of functional safety in the development, operation and support of electrical, electronic and programmable electronic systems (EEPES). There is a danger, of course, that the existence of IEC 61508 will be seen as the solution to a wider range of problems in the development of safety-critical systems than such a standard could be capable of addressing. The suitability of IEC 61508 for the specification of relatively simple protection systems is not in doubt. However, in considering how effectively IEC 61508 could be used in the more complex environment of transport-infrastructure systems, the paper discusses the fundamental nature of, and means of deriving, safety requirements and considers how effectively compliance to the Standard may be used to provide assurance that a system is safe. From these discussions, the paper concludes on the feasibility and value of system certification against IEC 61508.

Fault trees for security system design and analysis

<div class="section abstract"><div class="htmlview paragraph">Increasing demands for safety, security, and certifiability of embedded automotive systems require additional development effort to generate the required evidences that the developed system can be trusted for the application and environment it is intended for.</div><div class="htmlview paragraph">Safety standards such as ISO 26262 for road vehicles have been established to provide guidance during the development of safety-critical systems. The challenge in this context is to provide evidence of consistency, correctness, and completeness of system specifications over different work-products. One of these required work-products is the hardware-software interface (HSI) definition. This work-product is especially important since it defines the interfaces between different technologies. Model-based development (MBD) is a promising approach to support the description of the system under development in a more structured way, thus improving resulting consistency.</div><div class="htmlview paragraph">Therefore, this paper presents a tool approach for an ISO 26262 aligned hardware-software interface definition. More specifically, the approach combines the versatility and intuitiveness of spreadsheet tools (such as Excel) and the properties of MDB tools (e.g. different views, levels of abstraction, central source of information, and information reuse) bidirectionally. The approach is capable of defining an ISO 26262 compliant HSI definition and enables automatic derivation of basic software configurations according to the HSI definition. This simplifies concurrent development of software and hardware across domain and company borders.</div></div>