A Study On Vehicle Operating Safety Characteristics Based On Molecular Dynamics

Car following and lane changing behaviour are two factors influencing vehicleoperating safety，which have become an important content of drive behavior andvehicle active safety at present. Carrying out safety characteristics analysis forvehicle operating based on following and changing models, and structuring safetywarning system in vehicle operating applied into safety assessment and predictionfor road safety system, that has important theoretical value and practical significancein the aspects including solving the autonomous driving safety, following efficiencyand improving road safety.In this thesis, based on the National Natural Science Fund project:"State ofevolution for cooperative vehicles-infrastructure safety" and " Molecular dynamicsanalysis and the model of car following ", some critical issues have been given indeep study. Car following characteristics is analyzed using molecular dynamics,car-following model based on required safety distance is established; lane changingbehavior is analyzed, critical safety distance model is set up, and safety erea isdefined for lane changing; the stability of traffic flow operating safety is analyzed.The research of this dissertation can be summarized as following aspects:1. Analysis on driver behavior characteristics and the car-following behaviourare carried out. Based on molecular dynamics, the two nature state of car followingare systematically elaborated in car following, the state of "compression" in the "lowtemperature" and the state of "expansion" in the "high temperature"; and thenrequired safety distance is put forward, required safety characteristics is naalyzedfrom three aspects including front prior required safety distance, lateral requiredsafety distance and required safety distance, distance demand saturation coefficient isintroduced to quantitatively analyze and modeling dynamic and static required safetydistance.2. Car-following model of molecular dynamics is set up based on required safetydistance. Molecular dynamics was taken to analyze car following behavior and themolecular car following model with multiple stimulus is established. Based onstimulus-response model, giving the reaction weight to the items of distancedifference, velocity difference and prediction, using mathematical deduction method, the state equation is set up making known the drivers’ response to various stimuli. Theinfluence on car following of lateral required safety distance is analyzed from theaspects of longitudinal distance and the speed, and the model of lateral requiredsafety distance is set up.3. The dynamic characteristics of lane changing is analyzed, the conditionsavoiding the collision was studied at the lane changing process, the quantitativemodel of the criticality safety distance is developed in the concrete lane changingscene, simulation analysis is carried out on the model, on the basis of which definesthe safety area and no-safety area. Results show that by adjusting speed andlongitudinal spacing before lane changing, vehicles can reduce the possibility ofcollision. The research results can provide theoretical basis for automatic lanechanging auxiliary system.4. Based on the molecular dynamics theory, taking balance motorcade as theresearch object, the perturbation method is used to analyse the stability of traffic flowfrom the microcosmic and macroscopic aspects. Perturbation-following model is setup based on the required safety distance. Numerical simulation analysis is carried outapplying Matlab on the research conclusion of the perturbation method, the factorsaffecting stability of traffic flow and traffic security are obtained. The results havegreat significance for improving traffic capacity and road safety.