Safety of the Intended Functionality (SOTIF) based on System Theoretic Process Analysis (STPA): Study for Specific Control Action in Blind Spot Detection (BSD)

The rapid development of automotive technologies is leading to an increase in the complexity of vehicles. The probability and complexity of potential safety hazards in vehicles are concomitantly increasing. The reduction of risks associated with malfunctioning behavior of E/E systems is addressed in the ISO 26262 standard. Nevertheless, in light of the accelerated advancement of autonomous driving technologies and the concomitant growth in the number and complexity of vehicle components, including sensors and controllers, there is a standard which is a complementary of ISO 26262. The ISO 21448:2022 (Safety of the Intended Functionality, SOTIF) standard emerged from this need. In the context of SOTIF processes, a range of safety analyses have been proposed, including Cause Tree Analysis and Failure Mode and Effects Analysis (FMEA). Additionally, the System Theoretical Process Approach (STPA), which is gaining traction, is also being employed. STPA is frequently preferred, particularly for ADAS/AD functions in the automotive industry. In this study, STPA methodology is employed to evaluate the risks due to functional insufficiencies. The essential elements of SOTIF procedures, namely identification and evaluation of hazards (ISO 21448:2022, Clause 6) and the identification and evaluation of potential functional insufficiencies and potential trigger conditions (ISO 21448:2022, Clause 7), are compatible with the STPA methodology. The aforementioned compatibility will be demonstrated in the context of Blind Spot Detection (BSD) function through the application of the STPA steps. Consequently, the utilization of STPA in SOTIF studies represents a highly efficacious methodology.