Safety Compensation for Improving Driver Takeover Performance in Conditionally Automated Driving

The topic of transition from automated driving to manual maneuver in conditionally automated driving (SAE level-3) has acquired increasing interest. In such conditionally automated driving, drivers are expected to take over the vehicle control if the situation goes beyond the system's functional limit of operation. However, it is challenging for drivers to resume control timely and perform well after being engaged in nondriving related tasks. Facing this challenge, this paper investigated a safety compensation in which the system conducts automatic deceleration to prolong the time budget for drivers to response. The purpose of the paper is to evaluate the effect of safety compensation on takeover performance in different takeover scenarios such as fog, route choosing, and lane closing. In the experiment, 16 participants were recruited. Results showed no significant effect of safety compensation on the takeover time, but a significant effect on the longitudinal driving performance (viz. driver brake input and the time to event). Moreover, it indicated a significant effect of safety compensation on the lateral acceleration in the lane closing scenario. This finding is useful for the automotive manufacturers to supply users a safer transition scheme from automated driving to manual maneuver.