Functional safety analysis of SAE conditional driving automation in time-critical situations and proposals for its feasibility

The autonomous driving technology is rapidly developed for commercial use, aiming at the conditional driving automation or the third level of driving automation (LoDA 3). One of the most critical challenges for the achievement is the smooth authority transfer from the system to human drivers in an emergency. However, it is still on the way to find out fundamental solutions. The difficulty is closely related to the envisioned world problem, for which the concept of functional modeling could be a solution. This paper presents a safety analysis of the authority transfer problem based on the ideas of functional modeling. We discuss the safety of the authority transfer in a time-critical situation by using a simulator based on the functional resonance analysis method (FRAM). The result shows that the involvement of human drivers in driving activities is still essential even during autonomous driving. We show that the current LoDA 3 is a myth that the human drivers are supposed to be required just in non-normal situations, while they can be free from dynamic driving tasks (DDTs) in usual cases. Based on the result, this work makes some proposals for successful autonomous driving, effective human–machine collaboration, and the right design of artifacts.