Study On Pedestrian Kinematics And Multivariate Associated Characteristics In Vehicle/Pedestrian Collision

Vehicle/Pedestrian collisions are a common occurrence, can contribute to the larger portion of the total number of road crashes for most countries in today's society. Therefore, there will be of great practical significance to conduct the research on pedestrian's collision safety. Nowadays, pedestrian protection project has presently become the key aim that is paid attention by researchers in the fields of traffic safety and vehicle crash safety.The research on vehicle/pedestrian crash safety are presently developed by using various impact tests involving cadaver or pedestrian dummy, leg-form or head-form impactor, and computer simulation technique with in-depth analysis of real world data. Main studies cover the analyses of pedestrian kinematics, pedestrian dynamics, pedestrian injuries biomechanics and pedestrian protection technology in a vehicle/pedestrian collision. Due to the advantages of expeditious, economical, avoidable influence of random factors and test condition, easily simulating and comparing for different collision scenarios, as well as obtaining some parameters data which are very difficultly available through impact tests, computer simulating test has been of great application value and advantage in the research on vehicle/pedestrian crash safety.In this paper, the pedestrian is modeled as a multi-body system by using PC-CRASH simulation program and embedded MADYMO module; moreover, the influence laws and factors of pedestrian kinematics and its characteristic parameters under different collision circumstances are in depth studied and comprehensively revealed. The main studies involved in this paper are as follow.(1) The kinematics law of a pedestrian in a vehicle/pedestrian collision is fully researched by using computer modeling and simulating method in this paper. Based on the coupling of PC-CRASH and embedded MADYMO, Multi-body models of the vehicle and the pedestrian involved in a vehicle/pedestrian collision are developed and validated. Main factors influencing on pedestrian kinematics in vehicle/pedestrian contacting phase are extensively analyzed; furthermore, the simulating test scheme is constructed from these factors. The kinematics laws of pedestrian such as motion posture and vehicle impact speed threshold in vehicle/pedestrian contacting phase under different collision circumstances are in depth studied by selecting these main influencing factors as independent variables for simulating tests. The pedestrian kinematics simulation is found to be good harmonious and consistent with the case of real world and staged vehicle/pedestrian impacts. The computer modeling and simulating method documented in this paper will be of practical value in analysis of pedestrian kinematics in a vehicle/pedestrian collision.(2) The multifactor influence laws of contact location for pedestrian's head on the impacting vehicle exterior under different collision scenarios are in depth researched based on computer simulating test in this paper. Upward throw and lateral deviation distances are introduced to describe pedestrian's contact point on the impacting vehicle body surface. The impacting vehicle and pedestrian are respectively modeled as a multi-body system through the coupling of PC-CRASH and MADYMO. The influence laws and factors of upward throw and lateral deviation distances for the impacted pedestrian involved in a vehicle/pedestrian collision are in depth analyzed with simulating by selecting significant factors influencing on contact location for pedestrian's head on the impacting vehicle exterior as independent variables for simulating tests. At the same time, for various influencing factors, the approximate vehicle impact speed thresholds under different collision circumstances are determined from the available simulating data. On the other hand, the mathematical relationships between post-impact pedestrian's upward throw/lateral deviation distances and vehicle impact speed under different collision scenarios are derived from regression analyses of the simulating data. The findings have indicated that the derived regression equations may be used to access the lower vehicle impact speed and qualitatively analyze pre-impact pedestrian motion state or speed, which will be of great practicability in reconstruction analysis and technical appraisal of a vehicle/pedestrian collision.(3) The relationships comparing vehicle impact speed to pedestrian throw speed are in depth studied; moreover, the multifactor influence laws of projection efficiency under different collision scenarios are completely revealed in this paper. The mathematical models of impact projection efficiency are developed based on the kinematics theory and kinetics theory; moreover, various factors influencing on projection efficiency are determined. Consequently, the simulating test scheme for vehicle/pedestrian collision is design from the above factor analysis. In addition, the multi-body models of the vehicle and the struck pedestrian are developed by using PC-CRASH/MADYMO; moreover, the validity of vehicle/pedestrian impact model for calculating projection efficiency are validated by utilizing theoretical throw models. The influence laws and its effect for various factors on projection efficiency under different collision scenarios are in depth researched and revealed from the available simulating data by using SPSS; moreover, the equations and its curves for the projection efficiency as a function of vehicle impact speed are derived and validated.(4) The influence laws and its factors of pedestrian throw distance under different collision scenarios are in depth studied through simulating test for vehicle/pedestrian collision. Furthermore, the relationships between vehicle impact speed and pedestrian throw distance are developed from the simulating data. At the same time, the empirical models for various collision circumstances are derived from the real throw distance data; moreover, these models are compared to the throw models derived by foreign researcher and simulating throw models presented in this paper.It would have expected that the results in this paper can not only provide certain referenced value and guidance meaning for the studies on kinematics and dynamics of the struck pedestrian as well as increasingly developing technology appraisal of road crashes, but also make a great progress in the study on vehicle/pedestrian crash safety.