Integrated Simulation Analysis Of Restraint System Based On Automatic Braking And Active Steering

With the continuous development of automotive safety technology,active collision avoidance technology has become the focus of automotive safety research.However,the out-of-position displacements of the occupant in the longitudinal and lateral directions during the collision avoidance stage change the relative position between the restraint system and occupant,resulting in increased occupant injury indexes.At present,there is still little research on the protection of out-of-position occupants under the cooperative braking and steering conditions.Therefore,the study on the occupant injury risk caused by collisions after braking and steering maneuvers and the protective effectiveness of the restraint system has important guiding significance.Based on the typical types of pre-crash accidents and active safety test scenarios,an accident scenario similar with the actual traffic accident scenarios was constructed for this study and then a collision avoidance decision-making mechanism including automatic braking and active steering is introduced for the pre-collision simulation.This paper takes Toyota Yaris as the research object to complete the model construction and verification of the vehicle and the restraint system.At the same time,considering the ordinary dummies cannot fully reproduce the muscle response of the occupants before the collision,the Active Human Model(AHM)validated with the volunteer test is imported to simulate the muscle response of the occupants during the pre-collision phase.Finally,the boundary conditions of the collision between the two vehicles are obtained and the collision acceleration of the vehicle is extracted based on the LS-DYNA simulation according to the established accident scene,for the purpose of analyzing the occupant’s out-of-position response and injury indexes among the accident process.The simulation results indicate: the maximum head longitudinal and lateral out-ofposition displacements reached 143.3mm and 254.6mm with the original restraint system,which make the shoulder belt fall-off and the airbag breakdown during the collision.After adapting the 3-point Active Control Retractor(ACR),the maximum displacement of each part of the dummy was reduced by an average of about 40%,the chest and thigh injuries of the dummy were reduced by 23.6% and 44.4% respectively,and the fall-off of shoulder belt and the breakdown of airbag were eliminated.The effect of active-adjusting seat had a limited effect on the restraint of the dummy,which can only reduce the longitudinal displacement of the dummy by 20.9%,while the lateral displacement of the dummy does not change much.Therefore,although there was no head hard contact at the collision stage,the shoulder belt still appeared to fall-off.However,the lifting of the seat makes the dummy more restrictive to the lower limbs,which reduced the left and right femur forces of the dummy by 47.4% and 65.1% respectively.The adaptation of the 3+2 point ACR decreases dummy out-of-position displacement during the entire pre-collision phase,and reduces the chest compression by 35%.The combination of the 3+2 point ACR and the active adjustment seat has little impact on the out-of-position in the pre-crash stage,but can greatly reduce the injury indexes of the dummy in the collision stage,among which the chest compression of the dummy is reduced by about 35%,and the left and right femur forces were decreased by 68.4% and 99% respectively.The research results show that after making full use of the pre-trigger restraint system,it can not only ensure that the occupant in a normal sitting posture during the pre-collision phase,maintain the adapting relationship between the occupant and the original restraint system,and avoid head hard contact.Furthermore,the lifting of seats also increases the restraint between the seat and the dummy during the collision phase,significantly reduces the occupant’s lower limb injuries,and prevents the occupant from "sub-merging".This research provides the reference for future research and development of related technologies involved in active and passive integrated safety and puts forward some reasonable suggestions for the adaptation of pre-triggered restraint systems.