基于ITC的自动驾驶卡车编队跟驰安全性评价

Evaluation based on ITC of rear-end collision safety of automated truck platoons

为了在卡车编队技术大规模应用时控制编队跟驰冲突风险和减少追尾事故的发生,在传统的交通冲突评价方法上进行了改进,对自动驾驶卡车编队的跟驰安全性进行了分析和评价。考虑路面阻力和协同控制,对智能驾驶人模型(intelligent driver model,IDM)进行了改进,建立了考虑路面阻力的跟驰模型(IDM+)、融合协同控制策略(cooperative adaptive cruise control,CACC)跟驰模型2种适用于自动驾驶卡车的编队跟驰模型。然后以跟驰模型作为编队控制的基础,不考虑车辆控制的个体差异,通过MATLAB数值模拟试验,得到编队跟驰状态时变曲线,分析编队跟驰模型特征和稳定性。分别以距离碰撞时间(time-to-collision,TTC)和距离碰撞时间倒数(the inverse time-to-collision,ITC)2种碰撞时间函数作为评价指标,得到安全指标时变曲线,并比较2种指标的优缺点。基于数值模拟试验结果和ITC安全性判别准则对卡车编队跟驰安全进行了定性分析,以IDM+和CACC跟驰模型下的3辆卡车组成的编队为例进行了仿真试验。试验结果表明:CACC协同控制策略能提高卡车编队跟驰过程的稳定性,降低追尾风险;随着卡车编队中前后车的速度差增加,车辆追尾的风险呈现不断增大的趋势;ITC与前后车速度差成近似线性关系。该研究结果可用于卡车编队投入运营前以及运营过程中,对编队跟驰安全性进行评价和风险预警,防范追尾事故的发生。

To control collision risk and reduce the occurrence of rear-end collision accidents during the large-scale application of truck platoons, the traditional traffic conflict evaluation method was improved, and the safety of the self-driving truck platoons was analyzed and evaluated. Considering the road surface resistance and coordinated control, the intelligent driver model(IDM) was improved, and two car-following models suitable for self-driving truck were established, the car-following model considering the road resistance(IDM+) and the car-following model with cooperative adaptive cruise control(CACC). The car-following model was then applied as the basis for platoon control. Regardless of the individual types of vehicle control, the MATLAB numerical simulation experiment was used to obtain the time-varying curve of the platoons and the state of the car-following model. Two kinds of collision-time functions, time-to-collision(TTC) and the inverse time-to-collision(ITC) were used as evaluation indicators to obtain time-varying curves of safety indicators, and the advantages and disadvantages of the two indicators were compared. Based on the numerical simulation experimental results, and the ITC safety discriminant criteria, the qualitative analysis of truck racing follow-up safety was performed. Platoons of three trucks under the IDM+ and CACC car-following models were included in simulation experiments. The results show that CACC can improve the stability of the truck racing follow-up process and reduce the risk of rear-end collision. Also, with the speed difference between the front and rear vehicles increasing, the risk of vehicle rear-end collision tends to increase. There is an approximate linear relationship between the ITC and the speed difference between the front and rear vehicles. The results of the study can be used to evaluate the safety of truck platoons and provide risk warnings during planning of truck platoons and the operation process, to prevent the occurrence of rear-end conflict accidents. 3 tabs, 10 figs, 30 refs.