Target Failure Measures and Their Interval Estimations for E/E/PE Safety-Related Software

E/E/PE safety-related systems are applied in various industrial fields as safety systems that mitigate the hazardous risk of the entire system. Safety assessment of the E/E/PE safety-related systems provides important information for determining the need for risk mitigation activities. In particular, because the safety functions of the E/E/PE safety-related systems are controlled by software embedded in those safety-related systems, certain safety concerns exist not only for the hardware system but also for the software system. In this paper, we apply the concepts of existing software reliability modeling techniques to derivation of the target failure measures for quantitative software functional safety assessment of the E/E/PE safety-related systems. Furthermore, simulation-based interval estimation method for those target failure measures is discussed for considering the uncertainty of those measures based on the bootstrap method and bootstrap confidence interval. Finally, we present numerical examples of the proposed method to demonstrate our simulation-based interval estimation approach for quantitative software functional safety assessment.