前方车辆紧急刹车是引起前向碰撞事故的主要原因之一，如果驾驶员能够提前获取前车急刹信息，可由被动视觉刺激而采取的被动应对行为转变为基于心理预期的主动应对行为，将大幅度降低事故发生率。基于驾驶模拟技术设计了车路协同环境下前车急刹事件，该实验场景能够在距离前方急刹车辆 360m 和 290m 处利用车载人机交互设备 (HMI) 向实验车辆提供急刹预警信息。通过招募合格被试驾驶员并使其参与驾驶模拟实验，获得车辆行驶数据和各项评价指标。通过对有无车载 HMI 预警信息情况下的驾驶数据的对比分析，提出了一种基于时空图的车路协同环境中前车急刹情形下的驾驶特性分析方法; 并基于 35 名驾驶员的平均加速度特征对前车急刹事件情形下驾驶员驾驶自信特征进行分析。结果表明: 有车载 HMI 预警信息时，驾驶员在应对前方急刹事件时减速位置较无车载 HMI 预警信息提前; 有车载 HMI 预警信息提示情况下，面对急刹事件时驾驶员速度控制强度更低，通过曲率指标得出速度调整强度降低 39. 4%; 速度调整更加从容，表现出驾驶自信特征，在面对风险环境时能够主动应对。

Emergency braking event of the vehicle in front is one of the main causes of a forward collision． If the driver can sense the emergency braking event of the vehicle in front timely，the coping behavior can be changed from passive visual stimulation to active coping behavior based on psychological expectation，which will greatly re-duce the accident rate． Based on driving simulation technology，an emergency braking event in the cooperative ve-hicle infrastructure system was designed to provide the emergency braking warning information of the vehicle in front with the vehicle-mounted Human Machine Interface (HMI) at the distance of 360 m and 290 m． Driving behavior data and evaluation indexes were obtained from driving behaviors of qualified drivers in the driving simulation experi-ment． After a comparative analysis of driving behavior data with and without HMI warning information，a method was proposed for analyzing the driving characteristics of the emergency braking event of the vehicle in front in the cooperative vehicle infrastructure system based on spatiotemporal diagram． The driving confidence characteristics of
35 drivers in emergency braking event were analyzed based on their average acceleration characteristics． The re-sults show that when the HMI warning information is available，the drivers tend to decelerate earlier with lower speed control intensity than that when the HMI warning information is not available． According to the curvature in-dex，the speed control intensity is reduced by 39. 4%． When the HMI warning information is available，the speed control is more leisurely，and the drivers can proactively respond to the risk environment with the characteristics of driving confidence．