The bidirectional safety analysis & validation framework of system and software with its techniques and applications

Abstract

According to SAE ARP 4761, the system safety analysis and validation is a complex process which can be divided into three parts, namely, Function Hazard Analysis (FHA), Preliminary System Safety Analysis (PSSA), and System Safety Analysis (SSA). However, the existing researches rarely consider the integral implementation framework of FHA, PSSA and SSA, and the bidirectional interactive relationship between the system and its software/hardware items. Thus it is not only difficult to connect the three safety process with each other closely, but also difficult to apply the safety works into the development process of system and its software items effectively. To solve this application problem, first we propose a bidirectional safety analysis and validation framework of system and software in this paper, which is composed of the safety allocation process from system to software, and the safety validation process from software to system. Furthermore, we propose three safety techniques, namely the hazard analysis based on the abnormal output in FHA, the fault tree construction and hazard cause analysis based on the system architecture and software failure in PSSA, the model-based and data-driven software failure mode and effects analysis approach in SSA. Finally, we apply this framework and these new approaches on the typical airborne control software. The experiment results show that this new bidirectional safety framework connects the FHA, PSSA, and SSA together organically and can be integrated into the whole system and software development process closely, and construct a bidirectional closed loop of the data interactive relationship between the system and its software items.