Accident Reconstruction Methods Based On Uncertainty Theory And Strategy For Protecting Pedestrian-Ground Contact Injury

The number of traffic accidents and the number of deaths and injuries in China have shown a downward trend,but pedestrians still have a high casualty rate in traffic accidents.So pedestrian collision damage research and damage protection have become hot issues in the field of passive safety.In this paper,based on the data of real vehicle-pedestrian accidents,the research of the accident reconstruction and human-ground collision damage protection will be carried out.The research includes the techniques of reconstruction of vehicle-human collision,the uncertainty analysis of interval reconstructed results,the case-oriented approach for analyzing the uncertainty of reconstructed results,and the experimental design method of uncertainty analysis of reconstructed results.Finally,the sources and influencing factors of human body injury were analyzed and a protective strategy is proposed.By collecting vehicle head shape parameters from many real cases,the value range of 8 vehicle head shape parameters and relevant statistical data in PC-Crash are obtained after statistics.On this basis,the sensitivity of vehicle head shape parameters is further analyzed.Based on the understanding of the sensitivity of the vehicle head shape parameters are strengthening,the prediction model of vehicle speed in collision accident based on human body injury is established.Based on interval theory,subinterval perturbation method and Taylor's expansion formula,a subinterval perturbation algorithm is proposed,which can accurately calculate the interval of accident reconstruction results under binary interval traces and solve the problem of interval expansion.On this basis,combine the related algorithms of binary with the ternary interval theory,the problem of uncertain analysis of accident reappearance results under input of ternary interval and mixed interval is solved effectively.Furthermore,by introducing the sub-interval method,a method of analyzing the probability of vehicle overspeed is proposed.Uncertainty analysis is an effective methodology to improve the reliability of an accident reconstruction result.Many existing methods can be employed in this field,which can confuse a practicing engineer who does not know these methods well.To make the selection easier,a case-oriented approach was proposed based on the evidence theory.Users only need to input uncertain traces and a selected accident reconstruction model to calculate the uncertainty of reconstructed results using the proposed approach.By analyzing the basic test design methods used in simulation tests,combining the practical need of accident reconstructed results uncertainty analysis methods,the related experimental design methods are improved,Orthogonal-Based Design method and Multi-response surface Uniform Design are proposed respectively.Experiments are carried out through the PC-Crash platform and the sources of human injury in collisions between different vehicle types were explored.Simulation experiments are carried out on the MADYMO platform to analyze the relationship between human head and vehicle body's first contact time and human interaction time and human injury,then combined with the achievements of the human dynamic response,a pedestrian-ground collision injury protection strategy based on brake control is proposed,which can reduce human body injuries in vehicle-pedestrian accidents.