Introducing ASIL inspired dynamic tactical safety decision framework for automated vehicles

Existing automotive Hazard Analysis and Risk Assessment (HARA) process as discussed by the international standard ISO 26262 is static in nature. While the standard describes a systematic process to incorporate functional safety in the development process of Electrical & Electronic (E/E) systems, it fails to address the needs of Advanced Driver Assistance Systems (ADAS) and Automated Driving (AD) systems. In order to ensure the safety of ADAS and AD systems, it is important to incorporate the changing nature of interactions between the system and the environment, in the safety analysis process for ADAS and AD systems. In this paper, the authors argue the need for a dynamic approach for automotive safety analysis by adapting the tactical safety for ADAS and AD systems depending on the real-time operational capability and real-time ASIL (Automotive Safety Integrity Level) rating of a situation, and discuss a framework for this process. The novelty and therefore contribution of this paper lies in the proposed ASIL inspired dynamic tactical safety framework, which evaluates the severity, controllability and exposure ratings in real-time based on the real time values of the various vehicle and environment parameters. These ratings are used to assign a real-time ASIL value which is used to determine the tactical decisions in order to lower the ASIL value in real-time by altering the functional (operational) capability of the system. Furthermore, the framework is explained with the help of a case study based on a combined Adaptive Cruise Control (ACC) and Autonomous Emergency Braking (AEB) system.