Zeitschrift für Luft- und Raumfahrttechnik
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Architecture Level Safety Analyses for Safety-Critical Systems

Kushal KS*,Manju Nanda,Jayanthi J

The dependency of complex embedded Safety-Critical Systems across, Avionics and Aerospace domains, on their underlying software and hardware components has gradually increased with progression in time. Such application domain systems are developed based on a complex integrated architecture, which are modular in nature. Engineering practices assured with system safety standards to manage the failure, faulty and unsafe operational conditions are very much necessary. System safety analyses involves the analysis of complex software architecture of the system, a major aspect in leading to fatal consequences in the behavior of Safety-Critical Systems, provides high reliability and dependability factors during their development. In this paper, we propose an architecture fault modeling and the safety analyses approach that will aid in identifying and eliminating the design flaws. The formal foundations of SAE Architecture Analysis and Design Language (AADL) augmented with the Error Model Annex (EMV) are discussed. The fault propagation, failure behavior and the composite behavior of the design flaws/ failures are considered for architecture safety analysis. The illustration of the proposed approach is validated by implementing the Speed Control Unit of Power Boat Autopilot (PBA) system.

The Error Model Annex (EMV) guides with the pattern of consideration and inclusion of probable failure scenarios and propagation of fault conditions in the Speed Control Unit of Power Boat Autopilot (PBA). This helps in validating the system architecture with the detection of the error event in the model and its impact in the operational environment. This also provides an insight of the Certification impact that these exceptional conditions pose upon at various criticality levels, design assurance levels and its implications in verifying and validating the designs.