Engineering Of Safety-critical Systems Research Articles

Access: Assurance Case Centric Engineering of Safety-Critical Systems

Access: Assurance Case Centric Engineering of Safety-Critical Systems

Causality and Temporal Dependencies in the Design of Fault Management Systems

Reasoning about causes and effects naturally arises in the engineering of safety-critical systems. A classical example is Fault Tree Analysis, a deductive technique used for system safety assessment, whereby an undesired state is reduced to the set of its immediate causes. The design of fault management systems also requires reasoning on causality relationships. In particular, a fail-operational system needs to ensure timely detection and identification of faults, i.e. recognize the occurrence of run-time faults through their observable effects on the system. Even more complex scenarios arise when multiple faults are involved and may interact in subtle ways. In this work, we propose a formal approach to fault management for complex systems. We first introduce the notions of fault tree and minimal cut sets. We then present a formal framework for the specification and analysis of diagnosability, and for the design of fault detection and identification (FDI) components. Finally, we review recent advances in fault propagation analysis, based on the Timed Failure Propagation Graphs (TFPG) formalism.

Software Engineering of Safety-Critical Systems: Themes From Practitioners

This study addresses two important questions related to engineering of safety-critical software and software-intensive systems. The first question is: which software and software-intensive systems should be considered safety critical? The second question is: what processes, design practices, and tools have practitioners been using for building these systems? We answer these questions through an analysis of unstructured interviews with experienced engineers who self-describe as working on safety-critical systems. Then, a thematic analysis of these responses was conducted. The results of this study are intended to provide guidance to those building safety-critical systems and have implications on state engineering licensure boards, in the determination of legal liability, and in risk assessment for policymakers, corporate governors, and insurance executives.

Reuse of safety certification artefacts across standards and domains: A systematic approach

Reuse of systems and subsystem is a common practice in safety-critical systems engineering. Reuse can improve system development and assurance, and there are recommendations on reuse for some domains. Cross-domain reuse, in which a previously certified product typically needs to be assessed against different safety standards, has however received little attention. No guidance exists for this reuse scenario despite its relevance in industry, thus practitioners need new means to tackle it. This paper aims to fill this gap by presenting a systematic approach for reuse of safety certification artefacts across standards and domains. The approach is based on the analysis of the similarities and on the specification of maps between standards. These maps are used to determine the safety certification artefacts that can be reused from one domain to another and reuse consequences. The approach has been validated with practitioners in a case study on the reuse of an execution platform from railway to avionics. The results show that the approach can be effectively applied and that it can reduce the cost of safety certification across standards and domains. Therefore, the approach is a promising way of making cross-domain reuse more cost-effective in industry.