Abstract
To support quantitative functional safety (FuSa) concept development for an electro-mechanical brake (EMB) system, a fault injection (FI) method based on high-precision CarSim/Simulink co-simulation was employed to determine Automotive Safety Integrity Level (ASIL) ratings. The general development process of FuSa followed ISO 26262, which defines relevant items, and requires a comprehensive analysis of potential failure scenarios. In addition, failure mode analysis was performed using the HAZOP (Hazard and Operability Study) method, and fault tree analysis (FTA) was employed to investigate the root causes of braking function failures. For the risk assessment, thresholds for severity (S, measured by collision type and collision velocity difference), exposure (E, measured by scenario type and corresponding vehicle speed), and controllability (C, measured by time-to-collision, TTC) are defined using a parameterization method. The results shown that FI simulation can provide the real-time vehicle dynamic behavior for all hazardous events such as single or multiple wheel brake failures during EMB system braking, which are then compared against predefined thresholds to determine the severity (S), exposure (E), and controllability (C) levels for each operating condition, and ultimately the ASIL level and corresponding safety goals for EMB FuSa concept were generated. This quantitative assessment using the FI method could provide quantitative support for HARA (Hazard Analysis and Risk Assessment) analysis and subsequent functional safety development.
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