QaSten: Integrating Quantitative Verification with Safety Analysis for AADL Model

Abstract

Quantitative verification is an effective technique for analyzing quantitative aspects of a safety critical system's design, and safety analysis is a significant aspect of safety critical system. However, they are often conducted separately. In this paper, we propose a new methodology, QaSten, fastens quantitative verification to safety analysis for Architecture Analysis and Design Language (AADL) model (including error model). QaSten formalizes a set of rigorous transformation rules that transform AADL model to PRISM model using formal method. In addition, QaSten can generate two safety property formulas automatically to check against the PRISM model for each hazardous state. Therefore, the occurrence probability of hazardous states can be calculated, which can help system designers understand the impact of parameters in the model. Furthermore, combining the probability and the severity of potential consequence of a hazardous state, QaSten determines the hazard risk acceptance level that can help engineers to identify critical hazard and modify or redesign architecture model to control it in an acceptable level. Two case studies, based on the Gas Leakage Alarm systems, are utilized to demonstrate QaSten's feasibility and effectiveness.