In the automotive domain, functional safety is one of the most important aspects that need to be considered while developing a safety-critical system. Functional safety in road vehicles was standardized in 2011 when ISO 26262 was published. The standard gained a lot of interest and many companies now are using it including Daimler AG.
Hazard analysis and risk assessment (HARA) is described in part 3 of ISO 26262 and analyses the hazards and evaluate the risk. Despite the standard being used for so many years, this method has some limitation especially when applied to a complex system. For example hazards related to human behaviour are not taken into consideration, while the human is part of the system.
System-Theoretic Process Analysis (STPA) a modern method to hazard analysis developed by Nancy leveson at MIT and published in 2012. In STPA more causes of accidents, like human error, are taken into consideration.
The purpose of this thesis in broadening the scope of ISO 26262 by integrating STPA in part 3 of ISO 26262 that contains the hazard analysis and risk assessment methodology. This integration is described in a process diagram and guidelines were presented to help conduct the safety analysis using the new method. Later, it was applied to a Daimler’s automotive system that is the cruise control.
The results from previous analysis of the same system were compared with the result of the new method and 2 experts at Daimler AG evaluated the analysis and its results.
In conclusion, it was proven that STPA can be integrated in an ISO 26262 compliant process and that this integration can help increase the safety scope of the standard since more causes of accidents were found. The new method was proven to be feasible, beneficial and easy to learn. This thesis can be the starting point for many future works where the new method is further improved and applied to other automotive systems.
