Study On The Influence Of Different Gaits On Pedestrian Lower Limb Response During Pedestrian Accidents

In China,the number of pedestrian deaths during 2008-2017 is much higher than those of other major vulnerable road users.In 2017,the death toll of pedestrians alone accounted for 27.11% of the total number of traffic accident deaths.The existing research shows that in the process of exploring the collision between vehicles and pedestrians,the study on the active force of lower limb muscles of pedestrians is limited,and on the impact of different gait on lower limb injuries is not comprehensive.Therefore,the main purpose of this study is to discuss the influence of different gait and vehicle speed on lower limb injury in combination with muscle active force.In this paper,354 network videos of vehicle-pedestrian collisions were collected as case samples,and the collision positions of vehicles and pedestrians as well as the postures of pedestrians at the moment of collision were statistically analyzed.12in-depth pedestrian accidents were used to study the dynamic response characteristics of pedestrians’ lower limbs.In this paper,the validity of the hybrid pedestrian model is verified by comparing the data obtained from the simulation experiment with the kinematic experiment data obtained from the Kerrigan collision experiment of post-mortem human surrogates.The Toyota Yaris vehicle model is simplified,and a simplified human-vehicle frontal collision simulation model is established.The validity of the model is verified.Based on the simplified human-vehicle frontal collision model and statistical results,a simulation experiment scheme is designed to explore the influence of vehicle speed and pedestrian gait on lower limb injuries in traffic accidents.Accident video research and in-depth pedestrian accident research show that the probability of vehicles colliding the side of human body is the highest,accounting for76.3%,and the probability of pedestrians in walking posture is the highest,accounting for 41.5%,followed by running posture.Pedestrian’s posture will affect its dynamic response.The lower limb injury probability of pedestrians colliding with vehicles first is higher than that of pedestrians colliding with vehicles later,and the increase of vehicle speed will increase the lower limb injury probability of pedestrians.The finite element simulation research shows that in terms of dynamic response,the increase of vehicle speed will increase the peak value of bending moment and axial force of the femur and tibia of pedestrians,in addition the injury risk of the tibia of pedestrians is higher than that of the femur.The average of bending moment peak of tibia and femur of the lower limb first contacting with the vehicle are higher than those of the lower limb contacting with the vehicle later.According to the analysis of the average peak value of bending moment and axial force peak value at different speed,for femur,the bending moment peak value when pedestrians are running and the axial force peak value when walking are the lowest,while they are the highest when pedestrians are standing.For tibia,the peak bending moment of pedestrians is significantly higher when standing,and the peak axial force is the highest when emergency stopping.The bones with a higher probability of peak stress in the lower limb in contact with the vehicle first and after is the fibula and the foot bones,respectively.Based on the average value of stress peaks on the main bones of lower limbs,the stress on the main bones of lower limbs in standing posture is higher than that in walking,running and emergency stopping.To sum up,the statistical analysis results of pedestrian behavior in traffic accidents in this paper can provide real and direct data support for pedestrian safety research.The research results of different gait on lower limb injuries in traffic accidents in this paper suggest that pedestrian gait will affect lower limb injuries,and gait can be considered when studying pedestrian lower limb protection.