考虑风险等级的车车通信MTTC混合分布模型

Mixed distribution model of modified time-to-collision considering risk levels in vehicle-to-vehicle communication

摘要:

为研究车车通信环境下改进碰撞时间（modified time-to-collision, MTTC）的分布规律,建立能够描述不同车辆运行风险等级的MTTC混合分布模型,并利用实测数据进行模型验证,开展基于LTE-V技术的车车通信环境实验,获取实际车辆行驶实验数据,并利用k-means聚类方法将车辆运行风险划分为4种等级,利用Weibull、Gamma、对数正态3种概率分布模型,分别针对4种风险等级下的MTTC进行拟合检验,结果表明不同风险等级下的MTTC均可用对数正态分布模型描述。在此基础上,建立针对4种风险等级的MTTC对数正态混合概率分布模型,并利用EM算法对模型参数进行标定。选取Weibull、Gamma、对数正态概率分布模型作为对比,通过拟合优度分析验证所提出混合分布模型的有效性,并将该混合分布模型应用于一般环境下MTTC实验数据分析。结果表明:对数正态混合概率分布模型能够更好地拟合车车通信环境下的MTTC分布规律,并对一般环境具有良好的普适性,可为车辆运行安全相关研究提供理论支持。

Abstract:

To study the distribution rule of modified time-to-collision (MTTC) in vehicle-to-vehicle (V2V) communications, a mixed distribution model that can describe the MTTC distribution of different driving risk levels was proposed, and the model was verified by field test data. Experiment on V2V communications was carried out based on long-term evolution-vehicle (LTE-V) technology. Real vehicle driving test data was obtained, and k-means clustering method was used to divide the driving risk levels into four levels. Then, three probability distribution models including Weibull, Gamma, and lognormal were utilized, and the goodness-of-fit analysis was carried out for MTTC under four risk levels. Test results show that MTTC under different risk levels could be fitted well by lognormal distribution model. On this basis, an MTTC lognormal mixed distribution model for four risk levels was established, and the model parameters were calibrated using expectation-maximization (EM) algorithm. Three classic distribution models (Weibull, Gamma, and lognormal) were selected for comparison. The effectiveness of the proposed mixed distribution model was verified by goodness-of-fit analysis, and the mixed distribution model was applied to MTTC test data in conventional environment. Results indicate that the proposed lognormal mixed distribution model can fit the MTTC distribution better in V2V communication environment and has good adaptability to the conventional environment, which can provide theoretical support for related research on vehicle operation safety.