Interoperability between a dynamic reliability modeling and a Systems Engineering process – Principles and Case Study

International audienceIndustrial systems are often large, and complex, in terms of structure, dynamic interactions between subsystems and components, dynamic operational environment, ageing, etc. The dynamic reliability approach is a convenient framework to model the behavior of such systems. However, there is a price to pay, e.g. in terms of amount of data, size of state graphs, volume of reliability calculations, and combination of various engineering activities. A sound Systems Engineering process, benefiting from the improvement of most recent tools, may be a fruitful approach to decrease these difficulties. Although feasibility demonstrations have been done for conventional, static, approaches of dependability, interoperability between dynamic reliability modeling and Systems Engineering has not the same maturity level. The article explains how, on the basis of Systems Engineering (SE) process definitions, a Meta-model defines a framework for integrating the safety into SE processes. It supports a "hub automaton", that is the key element for interoperability with the tools and activities required for a dynamic reliability assessment. The case study is the dynamic assessment of availability of a feed-water control system in a power plant steam generator, presented in previous articles

Supporting ISO 26262 with SysML, Benefits and Limits

International audienceThis article deals with the issue of deploying efficiently the ISO 26262: the new standard in automotive systems development. The directives enclosed in this norm demands the establishment of a product lifecycle fully integrating the safety assessment activities. To tackle this subject, this paper explores the way of setting up Model-Based Design methodology to express and organize the concepts manipulated during the ISO 26262 process. This attempt is founded on the use of SysML and on the creation of a profile dedicated to ISO 26262 development context. We provide an introduction to Model-Based Design paradigm and its appli-cation in a safety relevant context. An overview of ISO 26262 is given, followed by the description of an on-going project on the subject. Modeling propositions are formulated and the use of diverse SysML diagrams are mapped on the automotive safety lifecycle process

Preliminary Hazard Analysis Generation Integrated with Operational Architecture - Application to Automobile

Abstract. We are witnessing evolution of standards (as the functional safety one) and increas-ing of complexity. This implies to perform safety studies efficiently and earlier in the context of Model-Based System Engineering. So, in this article, we will propose an evolution of the Pre-liminary Hazard Analysis (PHA) method in order to comply with the overall safety require-ments in the automotive domain. To demonstrate its usefulness, we apply this method to an industrial case which concerns the hazard analysis of unintended acceleration of a vehicle

A model-based rams estimation methodology for innovative aircraft on-board systems supporting mdo applications

The reduction of aircraft operating costs is one of the most important objectives addressed by aeronautical manufactures and research centers in the last decades. In order to reach this objective, one of the current ways is to develop innovative on-board system architectures, which can bring to lower fuel and maintenance costs. The development and optimization of these new aircraft on-board systems can be addressed through a Multidisciplinary Design Optimization (MDO) approach, which involves different disciplines. One relevant discipline in this MDO problem is Reliability, Availability, Maintainability and Safety (RAMS), which allows the assessment of the reliability and safety of aircraft systems. Indeed the development of innovative systems cannot comply with only performance requirements, but also with reliability and safety constraints. Therefore, the RAMS discipline plays an important role in the development of innovative on-board systems. In the last years, different RAMS models and methods have been defined, considering both conventional and innovative architectures. However, most of them rely on a document-based approach, which makes difficult and time consuming the use of information gained through their analysis to improve system architectures. On the contrary, a model-based approach would make easier and more accessible the study of systems reliability and safety, as explained in several studies. Model Based Systems Engineering (MBSE) is an emerging approach that is mainly used for the design of complex systems. However, only a few studies propose this approach for the evaluation of system safety and reliability. The aim of this paper is therefore to propose a MBSE approach for model-based RAMS evaluations. The paper demonstrates that RAMS models can be developed to quickly and more effectively assess the reliability and safety of conventional and innovative on-board system architectures. In addition, further activities for the integration of the model-based RAMS methodology within MDO processes are described in the paper

Characterizing the Identity of Model-based Safety Assessment: A Systematic Analysis

Model-based safety assessment has been one of the leading research thrusts of the System Safety Engineering community for over two decades. However, there is still a lack of consensus on what MBSA is. The ambiguity in the identity of MBSA impedes the advancement of MBSA as an active research area. For this reason, this paper aims to investigate the identity of MBSA to help achieve a consensus across the community. Towards this end, we first reason about the core activities that an MBSA approach must conduct. Second, we characterize the core patterns in which the core activities must be conducted for an approach to be considered MBSA. Finally, a recently published MBSA paper is reviewed to test the effectiveness of our characterization of MBSA

A Formal Framework for Modeling and Prediction of Aircraft Operability using SysML

Aircraft operability characterizes the ability of anaircraft to meet operational requirements in terms of reliability, availability, risks and costs. Airlines policy must cope with operational decision-making and maintenance planning to handle the impacts of any event that generates a maintenance demand during operations. Aircraft operability is therefore considereda major requirement by each airline. The subject reaches a complexity level that deserves investigations in a Model-Based System Engineering (MBSE) approach enabling abstractions, as well as simulation and formal verification of models. In this paper, aircraft operability is modeled using Finite State Machines(FSM) supported by SysML. Simulation and model checking techniques are used to evaluate the impact of an event on airline operations using operability Key Performance Indicators (KPIs)such as reliability, availability and cost. The modeling frameworkis demonstrated on a case study of air-conditioning pack. This kind of operability analysis helps to project the potential impactof aircraft design on airline operations early in the aircraft development