Research on design method of active energy absorption device for pedestrian classification protection

Intelligent driving technology has significantly enhanced vehicle safety performance, but the risk of pedestrian-vehicle collisions remains due to the uncertainty of the road environment. As vulnerable road users, pedestrians face significant threats to their safety. In pedestrian-vehicle collisions, physiological differences between adults and children result in distinct injury patterns. Therefore, it is essential to develop targeted protection strategies for both groups. This study aims to address the problem by proposing a classification protection airbag system that can dynamically adjust the airbag parameters to be deployed in different states to achieve the classification protection of pedestrians.

A pedestrian-vehicle collision numerical simulation model was established, and the general airbag was designed to protect the pedestrian. However, the general airbag failed to effectively protect the heads of an adult and child simultaneously. To address this issue, a classification protection airbag was designed, and its protection performance was investigated through finite element (FE) analysis. Additionally, an improved YOLOv5 pedestrian target detection model was proposed to realize the classification recognition for both groups. Based on the classification results, the vehicle control module can dynamically adjust the airbag parameters so that the airbag can be deployed to different states.

The general airbag 1 was effective in protecting the adult, though it caused more serious injury to the child. The general airbag 2 was effective in protecting a child, though it performed poorly in protecting an adult. It was found that the installation of classification protection airbag system can accurately identify pedestrians. Compared with the original YOLOv5 network, the precision (P), recall (R), and average precision (AP) of the improved network were increased by 3.63%, 1.42%, and 1.74% for adult recognition and 5.84%, 15.79%, and 11.86% for child recognition. Additionally, the classification protection airbag can effectively reduce the head injury of adults and children; its corresponding peak acceleration was reduced by 61.7% and 53.2%, and the head injury criterion (HIC) value was reduced by 63.4% and 31.4%.

The active energy absorption device designed in this study can realize the classified protection of pedestrians. The research results can provide reference for the design of a pedestrian protection device.