The Effectiveness of Proposed Pedestrian-Friendly Vehicle Front-end Shapes and Their Corresponding Controlled Braking Methods in Protecting Pedestrian Ground Contact Injuries

Previous studies have obtained some pedestrian-friendly vehicle front-end shapes, which show good pedestrian protection ability, but their effectiveness in protecting pedestrian ground contact injury has not been evaluated yet. For this reason, a total of 6 vehicle front-end shapes, 3 each for ‘Good’ front-end shapes (G shapes) and ‘Poor’ front-end shapes (P shapes), and a simulation test sample are selected to design 72 groups of 144 simulations. The results show that compared with the P shapes, the G shapes have better protection against pedestrian-vehicle contact injuries but worse protection against pedestrian-ground contact injuries. The analysis finds that the direct cause of the difference in the protection effect of pedestrian-ground contact injury between the G and P shapes is that the change in the pedestrian's ground impact mechanism leads to the head hitting the ground earlier and at a greater speed, and also higher ground-related weighted injury cost of pelvis (WIC pelvis ), while the essential cause is most likely the change in the angle of rotation of the pedestrian after the contact due to the difference in the shape of the bumper of the two types of vehicle. In order to further reduce pedestrian-ground contact injuries for the G shapes, 7272 simulations are designed and a simple vehicle braking control method for a specific vehicle model is proposed by combining optimization and regression. Experiments based on the simulation test sample show that a maximum reduction of 84% of the ground-related WIC can be achieved, with the proportion of safe mechanisms up to 74%. Experiments based on the new simulation test sample show a maximum reduction of 43% of ground-related head injury criterion (HIC), and the experiments show that the proportion of safe mechanisms reaches 78%, which verifies the good effect and adaptability of the proposed method.