为探究山区双车道公路行驶车辆的超车行为特性,基于无人机高空拍摄的超车行为视频数据,提出一种基于随机生存森林的超车持续时间预测模型.首先,利用Tracker软件提取超车行为相关车辆的行驶轨迹,并对超车行为特征进行分析;其次,采用非参...为探究山区双车道公路行驶车辆的超车行为特性,基于无人机高空拍摄的超车行为视频数据,提出一种基于随机生存森林的超车持续时间预测模型.首先,利用Tracker软件提取超车行为相关车辆的行驶轨迹,并对超车行为特征进行分析;其次,采用非参数Kaplan-Meier模型和全参数加速失效时间(Accelerated Failure Time, AFT)模型确定影响超车持续时间的关键协变量;最后,构建随机生存森林模型预测山区双车道公路的超车持续时间.结果表明:山区双车道公路平均超车持续时间为12.3 s,考虑超车类型的超车持续时间在无对向来车时表现出显著差异;相较于固定效应AFT模型,全参数AFT模型具有更好的拟合优度,超车距离、超车车辆最终速度、被超车辆类型是影响超车持续时间的关键变量;对比随机森林模型、生存支持向量模型、XG-Boost模型,随机生存森林模型在一致性指数和整合布里尔分数等方面均优于前三者,且考虑超车类型对山区双车道公路超车持续时间的预测效果影响较小;根据变量重要性排名,超车距离和两车的初始速度差对超车持续时间的影响较大.研究结果可为提高山区公路行车安全提供参考.展开更多
Previously we examined different parameters relevant to traffic flow. For illustrative purposes we considered a specific case of approaching a city. The case involves a traffic light where one continues on the main ro...Previously we examined different parameters relevant to traffic flow. For illustrative purposes we considered a specific case of approaching a city. The case involves a traffic light where one continues on the main road, into which additional cars are entering at the light. At this intersection an alternative route begins, which is longer but into which no additional cars are entering. In addition to the “Slow to move” model we add here a possibility of “overtaking”, which is quite artificial as our model is one dimensional. Still we think that this gives fair results.展开更多
Overtaking accidents caused by improper operations performed by a driver occur frequently. However, most stud?ies on overtaking safety have neglected research into driver control input. A novel method is proposed to o...Overtaking accidents caused by improper operations performed by a driver occur frequently. However, most stud?ies on overtaking safety have neglected research into driver control input. A novel method is proposed to obtain the driver control input during the overtaking process. Meanwhile, to improve the safety of overtaking, two types of safe distances, and the time of the overtaking are considered. Path constraints are established when considering the two types of safe distances. An optimal control model is established to solve the minimum time maneuver under multiple constraints. Using the Gauss pseudospectral method, the optimal control problem is converted into a nonlinear pro?gramming problem, which is then solved through sequential quadratic programming(SQP). In addition, the e ective?ness of the proposed method is verified based on the results of a Carsim simulation. The simulation results show that by adopting an inverse dynamics method to solve the manipulation problem of the vehicle’s minimum overtaking time, the manipulation capability of a vehicle in completing an overtaking safely within the minimum time can be obtained. This method can provide a reference for research into the active safety of manned and unmanned vehicles.展开更多
文摘为探究山区双车道公路行驶车辆的超车行为特性,基于无人机高空拍摄的超车行为视频数据,提出一种基于随机生存森林的超车持续时间预测模型.首先,利用Tracker软件提取超车行为相关车辆的行驶轨迹,并对超车行为特征进行分析;其次,采用非参数Kaplan-Meier模型和全参数加速失效时间(Accelerated Failure Time, AFT)模型确定影响超车持续时间的关键协变量;最后,构建随机生存森林模型预测山区双车道公路的超车持续时间.结果表明:山区双车道公路平均超车持续时间为12.3 s,考虑超车类型的超车持续时间在无对向来车时表现出显著差异;相较于固定效应AFT模型,全参数AFT模型具有更好的拟合优度,超车距离、超车车辆最终速度、被超车辆类型是影响超车持续时间的关键变量;对比随机森林模型、生存支持向量模型、XG-Boost模型,随机生存森林模型在一致性指数和整合布里尔分数等方面均优于前三者,且考虑超车类型对山区双车道公路超车持续时间的预测效果影响较小;根据变量重要性排名,超车距离和两车的初始速度差对超车持续时间的影响较大.研究结果可为提高山区公路行车安全提供参考.
文摘Previously we examined different parameters relevant to traffic flow. For illustrative purposes we considered a specific case of approaching a city. The case involves a traffic light where one continues on the main road, into which additional cars are entering at the light. At this intersection an alternative route begins, which is longer but into which no additional cars are entering. In addition to the “Slow to move” model we add here a possibility of “overtaking”, which is quite artificial as our model is one dimensional. Still we think that this gives fair results.
基金Supported by National Natural Science Foundation of China(Grant No.11672127)Fundamental Research Funds for the Central Universities of China(Grant No.NP2016412)
文摘Overtaking accidents caused by improper operations performed by a driver occur frequently. However, most stud?ies on overtaking safety have neglected research into driver control input. A novel method is proposed to obtain the driver control input during the overtaking process. Meanwhile, to improve the safety of overtaking, two types of safe distances, and the time of the overtaking are considered. Path constraints are established when considering the two types of safe distances. An optimal control model is established to solve the minimum time maneuver under multiple constraints. Using the Gauss pseudospectral method, the optimal control problem is converted into a nonlinear pro?gramming problem, which is then solved through sequential quadratic programming(SQP). In addition, the e ective?ness of the proposed method is verified based on the results of a Carsim simulation. The simulation results show that by adopting an inverse dynamics method to solve the manipulation problem of the vehicle’s minimum overtaking time, the manipulation capability of a vehicle in completing an overtaking safely within the minimum time can be obtained. This method can provide a reference for research into the active safety of manned and unmanned vehicles.
