Ensuring Functional Safety and SOTIF Analysis for Autonomous Off-Highway Vehicles: Addressing Risks in Complex Systems

The growing complexity of electronic systems and the rise of autonomous (driverless) vehicles in the off-highway industry emphasise the need for safer Electronic/Electrical (E/E) systems. In this paper, we present our approach to performing a comprehensive Functional Safety (FuSa) analysis and extending the scope to the application of Safety of the Intended Functionality (SOTIF) principles for off-highway vehicles. We apply FuSa to ensure that systems operate safely, by minimising risk through safety measures. This involves assessing risks based on potential hazards and deriving safety requirements in accordance with ISO 19014 and IEC 61508. Autonomous operation involves significant safety challenges. Thus, further analysis is needed to ensure the perception system functions safely and as intended in all scenarios. In the absence of a dedicated SOTIF standard for off-highway vehicles, we adapt ISO 21448 from the automotive industry for this analysis, as it is regarded as state-of-the-art and aligns with PAS 1883. This analysis assesses risks caused due to functional insufficiencies and misuse or accidental operations by humans. Finally, we develop a thorough SOTIF Verification and Validation (V&V) strategy by breaking down the hazardous event, based on understanding how SOTIF hazards may occur and lead to harm. This methodology enables the development of focused tests and analyses that address the system's intended functions while covering various hazards and hazardous scenarios. Additionally, it calculates the probability of harm occurrence and validates the acceptable risk criteria.