自动紧急转向导致斜角碰撞的一体化仿真分析

Integrated Simulation Analysis of Automatic Emergency Steering Leading to Oblique Collision

在前方道路突然出现障碍物的危急情况中,车辆采用自动紧急转向来避障,由于情况紧急,车辆在转向过程中仍可能与其他道路参与者发生碰撞事故。当车辆采用自动紧急转向避让道路前方路口突然闯入的车辆时,与对向来车发生斜角碰撞,由此,对该特定场景的转向-碰撞全过程进行一体化仿真,分析乘员在转向阶段因车辆横摆和侧倾运动引起的离位现象以及离位在碰撞过程中对乘员的动态响应和损伤造成的影响。首先,建立由自动紧急转向导致的斜角碰撞场景;其次,在该场景中,确定车辆在最小避障距离内的紧急变道路径,并计算车辆和乘员在变道过程中的动态响应;碰撞事故发生时刻选取为本车在紧急转向过程中易与对向来车发生碰撞的时刻,且在该时刻乘员具有较大潜在损伤风险;然后,在时域上结合车辆转向阶段和碰撞阶段的运动响应,将其作为整体输入,对乘员在全过程的动态响应进行一体化仿真;最后,分析离位对乘员损伤的影响规律以及影响因素。研究结果表明:紧急转向会导致乘员产生明显的横向离位,降低了约束系统对乘员的保护效果,致使乘员头部和颈部在碰撞中的人车相对运动速度和相对位移明显增大;横向离位使得乘员头部偏离安全气囊中央区域,降低了安全气囊的保护作用;这2个因素导致了乘员头部损伤评价指标HHIC36增加7.20倍,颈部损伤评价指标Nij增加2.32倍;乘员头、颈部损伤具有随横向离位程度减小而减小的趋势。

In the critical situation where obstacles suddenly appear on the road,the vehicle adopts automatic emergency steering to avoid obstacles. However,due to an emergency,the vehicle may still collide with other road participants during the steering process. When the vehicle uses automatic emergency steering to avoid a sudden intrusion on the intersection ahead,an oblique collision with the oncoming vehicle occurs. For this specific scenario,this paper performed an integrated simulation of the entire steering-collision process. The occupant’s dislocation phenomenon caused by the yaw and roll motion of the vehicle during steering and the influences of the dislocation on the dynamic response and injury of the occupant during the collision were studied. First,an oblique collision scene caused by automatic emergency steering was established. Second,the emergency lane change path of the vehicle within the minimum obstacle avoidance distance was determined in this scenario. Simultaneously,the dynamic response of the vehicle and occupant during the phase were calculated. The time of the collision accident was selected when the host vehicle was liable to collide with the oncoming vehicle during the emergency steering process. At the same time,occupants had a quite high potential risk of injury. The vehicle motion responses at the steering and collision stages were combined in the time domain. When this was input as a whole,the dynamic response of the occupant in the whole process was integrated through a simulation. Finally,the regular pattern of lateral dislocation on occupant injury and its influencing factors were analyzed. The results show that the emergency steering will cause the occupant to have an obvious lateral dislocation. The lateral dislocation breaks the relative position between the occupant and the shoulder belt,which reduces the restraining effect of the shoulder belt on the occupant’s upper limb,resulting in the relative movement speed and relative displacement of occupant’s head and neck,which significantly increased. On the other hand,the lateral dislocation causes the occupant’s head to deviate from the central area of the airbag,reducing the protection of the airbag. The above two factors increase the head injury criterion( HHIC36) by 7. 20 times and the neck injury indicator Nijby 2. 32 times,respectively. In addition,the head and neck injuries of the occupant tend to decrease as the degree of lateral dislocation decreases.