As part of its mission to save lives, prevent injuries, and reduce economic costs due to road traffic crashes, the National Highway Traffic Safety Administration (NHTSA) researches methods to ensure the safety and reliability of emerging safety-critical electronic control systems in motor vehicles. As advanced driver assistance systems and other emerging technologies are introduced into new motor vehicles, the overall safety of these advanced electronic systems relies in part on the safety of the underlying foundational systems, such as steering systems.

This study applies the Concept Phase (Part 3) of the ISO 26262 industry standard to two generic representations of foundational steering systems – electric power steering (EPS) and steer-by-wire (SbW). The generic EPS and SbW system architectures were developed based on interviews with industry subject matter experts and through literature describing existing EPS and SbW system designs. The paper outlines one approach to performing a Hazard Analysis and Risk Assessment (HARA) and developing a Functional Safety Concept. The approach incorporates several analysis methods, including Hazard and Operability study, Functional Failure Modes and Effects Analysis, and Systems-Theoretic Process Analysis. This approach is then applied to the EPS and SbW systems to identify vehicle-level hazards, and derive safety goals and functional safety requirements.

The paper presents the vehicle-level hazards and safety goals derived from the analysis and includes a discussion of “fail- safe” and “fail-operational” needs, which may inform the derivation of functional safety requirements. The results of this study may serve as an example for how different analytical methods could be applied to develop a functional safety concept. This study is primarily illustrative of the methods and is not intended to reflect a minimum set of safety requirements for existing or future foundational steering systems. Therefore, this paper does not provide any