Research On Decision Method For Vehicle Crash Safety System Based On Risk Assessment

To accurately evaluate the potential real-time crash risks of driving and help to decide control outputs of Vehicle Crash Safety System(VCSS),the following work was researched in the project.Firstly,research procedures are successively executed by background research,putting forward problems,modeling risk,recognizing risk,evaluating risk,risk decision-making and applying in driving examples.A decision method was proposed by analyzing the background of decision method for vehicle crash safety based on risk assessment.Secondly,the evaluation system of expert weight was expanded according to the characteristics of vehicle safety industry and the standards of evaluation indexes were built up.The authority cluster of expert aimed at evaluation indexes were carried by SPSS,also the weight of expert authority were calculated by SPSS.The similarity of dates which were provided by the experts was calculated by MATLAB,and then a threshold was set to cluster the experts and the weight of experts' suggestions was calculated.A method of group decision based on the multi-clustering weight analyze of expert was synthesized the weight of expert authority and experts' suggestions,which was laid a new foundation for datum analysis of the following expert questionnaires.Thirdly,a new risk model for vehicle crash risk was proposed which based on the industry system model of risk,energy transfer theory and the method of major danger recognition on the base of energy,replacing the risk probability with coefficients of both objective and subjective combined vehicle crash risk and substituted the energy generated in the vehicle crash for the risk consequences.The new quantized model can provide a basis for the following decision-making of vehicle crash risk.Fourthly,the fault tree of vehicle crash accidents was built up by analyzing databases and existing researches of traffic accidents.Combining the calculation of fault tree and human reliability analysis,the vehicle crash risk factors during drive were identified.Consider greatly influential objective and subjective risk factors in traffic accidents as main monitoring indexes of VCSS to establish the system's structure and determine signal input and commandoutput.Fifthly,make the indexes referred to in the expert weight calculation and vehicle crash risk factors as research items,design questionnaires and consult experts to get datum of both judgment matrix in analytic hierarchy process and membership matrix in fuzzy comprehensive evaluation to support the quantized risk assessment method.Sixthly,the weight of each risk factor was gained by the YAAHP(analytic hierarchy process software)which was integrated the results of expert questionnaires and expert weight calculation,and then the results were used in the adjusted fuzzy comprehension evaluation,in which the membership matrix was obtained from the expert surveys.The final matrix calculation could only include actual monitored risk factors.At last according to corresponding system,calculations were defined as combined objective and subjective crash coefficient,important evidences to determine risk assessment.Seventhly,based on the model of vehicle crash risk and combined crash risk coefficient,classify the risk of the real-time monitored vehicles.The assessment levels were treated to be important basis to decide command outputs of VCSS and to practically refine functions of system,which may lay a foundation for the combined VCSS,and then the results of the evaluating risk were checked by applying to the traffic accident databases and results of accident research.Eighthly,based on serial researches on thread shear type of energy absorbers,especially for Zotype 2008 Car,design hardware of energy absorber controlled by electrical system in the Protel and encode software in C language.Then the energy absorber was applied to Zotype 2008 Car,which could automatically adjust the capacity of energy absorption according to the level of velocity,and the conceive improvements of energy absorbers was proposed,which laid the foundation for perfecting the VCSS in the future researches.The decision method for vehicle crash safety based on risk assessment presented in this article lays the groundwork of active and passive combined vehicle crash safety system and the future intersection central control system and the Vehicle-to-Vehicle(V2V)communications system.In the method,safety risk factor assessment during drive were comprehensively analyzed and quantized which made it possible for VCSS to make command outputs not only based on the speed and the distances between vehicles and barriers but alsoon multiply monitored risk factors.As a result,driving experience decreased by frequent work of traditional automatic braking system which considered distances as the sole parameter could be greatly improved,and the limitations of the study solely by the accident databases could be overcome.