P-AEB performance and limiting factors for superior-rated P-AEB systems based on simulations of real-world pedestrian...

Pedestrian automatic emergency braking systems (P-AEB) have recently been introduced in the vehicle fleet to reduce vehicle-to-pedestrian collisions. However, studies on the real-world efficacy of these systems have yielded mixed results. To better understand the factors that influence P-AEB performance, previous simulation and counterfactual studies have evaluated the effects of different P-AEB characteristics on collision avoidance. Previous studies have focused on using a hypothetical P-AEB response model to either estimate the potential benefit of P-AEB or evaluate system configuration performance to optimize P-AEB design. This study aimed to understand the shortcomings of current production P-AEB systems for consumer testing organizations to use for encouraging the continuous improvement of those systems. The present study re-simulated 64 vehicle-to-pedestrian collision cases included in the in-depth Vulnerable Road Users Injury Prevention Alliance database to evaluate the stochastic response of rating-specific P-AEB systems and identify the most challenging pedestrian scenarios and the factors limiting P-AEB performance. Our P-AEB models represented the test responses of systems rated as superior, advanced, or basic by the Insurance Institute for Highway Safety (IIHS). We explored the effects of detection range, detection angle, and the lateral distance threshold for system activation. Results indicated a clear correlation between collision avoidance and the IIHS P-AEB rating. The study also identified three challenging scenarios: (1) highly obstructed cases, (2) high-speed vehicle cases, and (3) cases with high pedestrian crossing speed. None of the explored system designs were able to eliminate collisions in highly obstructed cases due to the late appearance of the pedestrian. In high-speed vehicle cases and in those with high pedestrian crossing speeds, P-AEB performance was limited by the detection range and the lateral distance threshold, respectively. Consumer testing organizations can use these findings to revise existing test programs, improve program relevance for vehicle-to-pedestrian crashes, and incentivize improvements to P-AEB systems.