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Warning model for safety analysis of overtaking behavior based on longitudinal safety spacing

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Abstract

At present, overtaking accidents on highway frequently occur with serious consequences. Aiming at this problem, a warning model is proposed for preventing overtaking safety. First, the main factors influencing the safety of overtaking are analyzed. Next, overtaking collisions are categorized and overtaking scenario is developed. Then, by describing overtaking trajectories and by using a kinematic model of vehicles, a warning model of preventing overtaking collisions is established, which includes a critical longitudinal safety spacing model and a time-spa-cing model. Finally, the effectiveness of the model is verified by using two instances, namely, constant-velocity overtaking and specific-acceleration overtaking.
华南理工大学学报(自然科学版)
41 8Journal of South China University of T echnology Vol. 41 No . 8
2013 8Natural Science EditionAugust 2013
文章编号1000-565X201308-0087-06
收稿日期2012-09-15
*基金项目国家自然科学基金资助项目511081925120850011147128) ; 华南理工大学中央高校基本科研业务费专项资金
资助项目x2tjD2115990
作者简介游峰1977-) ,
博士
副教授
主要从事交通协同安全与控制
车辆安全辅助驾驶
智能交通等的研究. E-mail
youfeng@ scut. edu. cn
通信作者张荣辉1981-) ,
博士
副研究员
主要从事智能车辆
车路协同与安全控制研究. E-mailzrh1981819@ 126. com
基于纵向安全距离的超车安全预警模型*
游峰1张荣辉2 王海玮1温惠英1徐建闽1
1. 华南理工大学 土木与交通学院广东 广州 510640
2. 中国科学院 新疆理化技术研究所新疆维吾尔自治区 乌鲁木齐 830011
摘 要目前
在高速公路上因超车导致的交通事故频发且后果严重为此
提出了超车
安全的预警模型首先分析了车辆超车安全的影响因素;然后对超车过程发生的碰撞进行
分类
并建立超车场景;进而通过对车辆超车时运动轨迹的分析
结合车辆的运动学模型
以车辆间的临界纵向安全距离作为安全超车的目标
兼顾车辆间车头时距
构建了超车过
程中车辆碰撞的预警模型;最后以匀速超车和特定加超车为
验证了模型的有效
关键词智能车辆;超车;安全;纵向安全距离;时距模型
中图分类号U491 doi:10. 3969 /j. issn. 1000-565 X. 2013. 08. 014
超车是驾驶员最为常见的驾驶行为之一据统
在高速公路上驾驶员以 90 km / h 行驶 100 km
距离
途中将进行大50 次超车行为在自由流状
态的高速公路
超车行为更为频繁1实施超车
驾驶员必须根据当前的车速
车辆间距
车流状
态以及道路交通设施等周边环境信息
实时调整驾
驶策略实现超车行为该过程包括超车环境信息收
集与处理
超车时机判
超车轨迹生成
超车碰撞
检测
超车冲突处理和超车行为实施等在如此复杂
的过程中
驾驶员极可能误判超车的可能性和可行
从而使车辆处在潜在的碰撞危险之中研究发
避免超车过程引发的车辆碰撞可通过控制车辆
间的相对速度和增加车辆纵向间距来实现
如此将
有效减少车辆超车过程发生碰撞的概率
但势必大
幅降低道路的通行能力
近年
我国因超车不当引发的交通事故呈明
显上升趋势
尤其是在高速公路上60% 以上的交
事故都与超车有关2如何提高超车安全已成为亟
待解决的交通安全问题
目前国内外有关超车的研究成果主要集中在超
过程的换道阶段
国外学者提出 GIPPS3
MITSIM4SITRAS5CORISM 6经典换道模
国内学者也针对换道方面展开了相关研究
如王
军雷等7分析了换道时车辆运动状态
探讨了避
免发生碰撞的条件
计算了不发生碰撞的安全距离
王荣本等8使用最小安全距离作为安全换道的指
研究车辆碰撞的条件
并给出了换道最小安全距
离的计算方法徐慧智等9构建了车道变换行为期
望运行轨迹
应用基于缓和曲线的轨迹形式
分析了
安全距离对运行速度和车辆侧向加速度的影响
伦辉等10研究了换道车辆完成换道的跟驰安全性
以提高道路的使用效率李玮等11以四段式车道变
换理论为基础
提出了车辆自由换道轨迹函数
建立
了高速公路车辆自由换道模型王永明等12等应用
元胞自动机探讨了弹性的换道间距邹智军等13
车道变换分为强制性和任意性车道变换
建立发车
道变换意图
车道变换可行性分析以及实施行为的
模型陈斌14引入多智能体理论
建立基于多智能
体主体系统的车道变换模型框架笔者也曾研究了
理想情况下换道车辆的防碰撞条件
并以此为基础
研究了车辆的安全换道轨迹15上述研究工作为超
车安全的研究奠定了基础
但大都基于传统的安全
距离模型
研究主要集中在换道需求分析和简化换
道间距检测上
研究成果过于保守
为此
在前人研究工作的基础上
笔者针对超车
安全的预警方法和超车过程中车辆安全间距展开研
首先
分析超车安全的影响因素然后
分析超车
时车辆碰撞的4种类型
包含车辆追尾碰撞
车辆斜
向碰撞
车辆横向刮擦以及车辆偏离车道与道路设
施发生的碰撞进而建立超车的场景
以此为基础
给出超车时间段以及超车车辆各个关键角点的定
再通过分析车辆间的纵向安全距离
结合车辆的
运动学模型
兼顾车辆间车头时距
构建了超车过程
中车辆碰撞的预警模型最后
针对车辆以匀速和以
特定加速度超车时安全区域与非安全区域的判定进
行了仿真演算
1影响车辆超车安全的因素分析
实施超车时
驾驶员必须根据当前的车辆速度
车辆相对距离
当前车流状态以及道路交通状况等
交通运行环境信息
实时调整驾驶策略
实现超车行
因此
分析与超车有关的安全影响因素可为文中
研究的开展奠定基础安全影响因素见表 1
1影响超车安全的因素
Table 1 Influencing factors of overtaking process
车辆超车期望 超车安全影响因素
超越前方低速车辆 相邻车道的车头
预期
车辆相对
速度
车辆速度
超车进入车辆队列 车辆队列的间距
期望到达车道与当前车辆
队列速度的差异
不同车辆间的车头间距
超车进入低速车道 停车距离
低速车道的车间距
车辆减速
车辆当前速度等
2超车安全预警分析
2. 1 预备知识
2. 1. 1 超车碰撞类型
为便于展开超车安全的分析
将超车过程中车
辆发生的碰撞分为4车辆追尾碰撞
车辆斜向碰
车辆横向刮擦以及车辆偏离车道与道路设施发
生的碰撞
如图 1所示
1超车碰撞类型
Fig. 1 Collision classes in overtaking process
2. 1. 2 车辆超车场景的建模
为便于展开超车过程研究
文中建立典型的超
车环境模型如图 2所示
图中 Vo为超越车辆
即实
施超车行为
以某一特定的横向加速度从当前车道
实施超车行为到达相邻车道. Vf1 Vr1 分别为与 Vo
车道的
后车辆Vf2 Vr2 分别为与 Vo邻车道的
后车辆xOy 为世界坐标系统x轴为道路水平
方向即为纵向) ,yx轴的法线方向. x 轴和 y
轴的正向如图中所示¨xj¨yjxjyjxjyj分别表示
j车的纵向
横向加速度
纵向速度
横向速
纵向位移
横向位移下标 j代表不同位置的车
jVoVf1 Vr1 Vf2 Vr2
2典型超车场景图
Fig. 2 Model of typical overtaking scenario
2. 1. 3 超车时间片定义
将超车过程所需时间进行分段处理
3所示每个时间段的定义见表 2
3超车时间段分割图
Fig. 3 Definition of time segment for overtaking
88 华南理工大学学报(自然科学版)41
2超车时间段的定义表
Table 2 Definition of time segmented for overtaking
超车时间段名称 超车时间段定义
t0驾驶员产生超车意图的瞬间
文中取 t0= 0
tadj Vo车实施超车行为前的调整时间
tc+tadj Vo车到达发生碰撞临界点的时间段
tlat +tadj
Vo以横向加速度行驶至相邻车道所对应的时
间段
T完成超车的时间
2. 1. 4 超车车辆关键角点定义
如图 4
中选Vo4
即左前角点
左后角点
右后角点
右前角点
别为 pii= 1234
4超车关键角点的定义
Fig. 4 Definition of key corner points in overtaking process
Vo车左前角点位置为 yVop1
根据各个角点间
几何关系
3个角点均可由式13
求出
yVop2 yVop1 lVosin θ1
yVop3 yVop1 lVosin θ+wVo sin θ 2
yVop4 yVop1 wVocos θ3
式中lVo wVo
θ分别为 Vo车的长度
宽度和方向角
2. 2 超车车辆的运动学建模
如图 5所示
Vo车左前p1为参考点Vo
完成超车时所对应的横向位移为 Wlane
即为车道宽
Vo车到达 Wlane /2
其横向加速度达最大
然后逐步减小当车辆到达相邻车道时
横向加
速度变为0
5超车过程车辆运动学分析
Fig. 5 Kinetic analysis of vehicles in overtaking process
假定 Vo车实施平稳超车
Vo向速
p1点的横向位移分别为 yVo yVo 中借鉴文16
提出的方法来描述 yVo yVo
如式45所示
yVo = Wlane
tlat
cos 2
tlat
ttlat
( )
+Wlane
tlat
4
yVo = Wlane
tlat
sin 2
tlat
ttlat
( )
+Wlane
tlat
ttadj
5
Vo车对应的方向角 θt
tan θt=yVo t
xVo t=
yVo t
t
xVo t
t
=yVo t
xVo t6
如图 2
Vo车超车时
与车辆 Vf1 Vf2
Vr1 Vr2可能发生碰撞为有效避Vo车碰撞事
故的发生
必须考虑超车场景中车辆间的纵向距离
和横向距离鉴于超车过程的复杂性
同时受文章篇
幅所限
重点研究 VoVf1 Vo车在同一车
道的前方车辆在超车过程的运动状态
以期建立
超车车辆的动态模型
如图6所示
BL 线为 Vf1 车的左侧边界线. Vo
车在 t= 0 时刻开始实施超车行为Vo车以横向加
速超车前车速的调整时间为tadj . VoVf1
生碰撞的类型为车辆斜向碰撞或车辆追尾碰撞
Vf1 车在原车道上保持匀速行驶
即满足条件
¨xf1 = 0¨yf1 = 0Vo车以一定横向加速度穿BL
线时Vo车右前角点 p4极易与 Vf1 车发生碰撞Vo
经过时tc+tadj Vop4点刚好经过 BL 线
并与
之交于 pc
tc+tadj Vo车到达碰撞点的
时间
6本车与前车的安全距离
Fig. 6 Safety spacing between host and front vehicle
ttadj
如果 Vo车仍未实施超车行为
易与
前车 Vf1 发生追尾碰撞当在 tadj ttc+tadj
如果
Vo车实施超车行为
易与前车 Vf1 发生斜向碰撞
合式3) ,
t=tc+tadj Vo车右前角点 p4的横向
位移为
S=yVf1 yVo twVo cosθt) ) 7
根据式6) ,
上式可改写为
S=yVo twVo
xVo t
x2
Vo t+y2
Vo t
8
98
8 游峰 等基于纵向安全距离的超车安全预警模型
分析此情况下车辆间的运动关系VoVf1
车的安全预警条件为
xVo txf1 tlf1 wVosin θt 9
式中t
0tc+ta dj lf1 Vf1车的长度
它是关于超
车时间的函数
9中的最后一wVo sinθt) ) 引入能确
保整个超车过程中 Vo车的右前角点与 Vf1 车的车尾
不发生任何形式的θtsin θt取得
最大值时对应的时间段为 t=tc+tadj
使lL1 =lVo +
maxsin θt)),
9可简化成
xVo txf1 tlL1t
0t0+ta dj 10
Srt=xf1 tlf1 xVot 11
t
0tc+ta dj
只要确保 Srt> 0Vo车与 Vf1
车就不会发生任何形式的碰撞17
Srt=Sr0+t
0t
0¨xf1 ¨xVo ) ) d d +
xf1 0xVo 0) ) t> 0 12
上式中 Sr0=xf1 0lf1 xVo 0由此看出Vo
车与 Vf1 车不发生碰撞的 Sr0的最小值即为两车不
发生任何碰撞的最小安全距离 min S
min S
{
(
=max t
0t
0¨xf1 -¨xVo d d +xf10-xVo0) )
)
t
}
0
13
分析上式VoVf1 车的最小安全距离
min S的主要影响因素由相同车道内两车间的纵向
加速度
相对初速度和超车时间 tc+tadj 构成tc+
tadj 决定了实施换道车辆的横向位置 yf1
横向位移时
tlat 和调整时间 tadj
在实际行车过程中
超车车辆一般以较小的相
对速度跟随前车行驶
通过上述影响因素求解出的
安全距离与实际超车过程存在较大误差事实上
了保证超车安全
除考虑上述原因外
还应考虑车间
的相对时距文中给出了基于车头时距的安全跟踪
模型
其表达式为
Dt=cxVo txf1 t) ) +D014
式中c为车头时距c1 ~ 2 sD0为安全停车距
通过以上分析可
为满足安全跟随距离
超车
的安全跟随距离如式15所示
当车辆间间距小于
该值时Vo车发出预警信息
S'rt=Srt+Dt 15
3模型
如图 6Vo车实施超车行为Vf1 始终在当
前车道上向前匀速行驶
xf1 = 0文中对两种情况
进行仿Vo车维持车辆纵向速度不变
xVo = 0Vo车以特定的加速度进行超车正常超车情
况下
车辆维持较高车速
因此车辆的方向角不应太
有关文献18 -20建议取 5°为宜
3. 1 Vo车以恒速超车的情况
由式12可知Vo车和 Vf1 车不发生碰撞的条
件可简化为
Srt=Sr0+xf1 xVo t> 0 16
min S= maxxVo xf1 0 17
此时 Vo车和 Vf1 车的相对速度为常数
12
简化为
min S=xVo xVf1 ) ( tc+tadj ) , xVo x Vf1 0
0
{
其他
18
18描述匀速行驶情况下 Vo车超车过程中
Vf1 车的安全纵向车距tlat 为超车平
稳性的动态特征参数tlat 越小
超车过程完成时间越
车辆运行状态越不平
易发生侧滑甚至侧翻
tlat 越大
超车完成间越
超车轨迹平缓
但由于
超车车辆长时间跨线行驶
易发生刮擦或角碰
超车完成时间 T= 50 stadj = 0Wlane1 = 3 5 m
车时间约为 5 s21-227中描述了超车场景中 Vo
车与 Vf1 在纵向相对速度与纵向相对间距之间的关
当车辆间的运动参数朝箭头相反方向变化
并超
7恒速条件下 Vo车与 Vf1 车辆的碰撞区域
Fig. 7 Collision regions between Voand Vf1 under the condi-
tion of constant velocity
09 华南理工大学学报(自然科学版)41
越安全临界线时
按前述分析
即可认为 Vo车实施
不安全超车行为
预警信号触发
3. 2 Vo车以特定加速度超车的情况
Vo车实施超
Vf1 车纵向间距过小或
相对速度偏大
驾驶员出于安全考虑
调整 Vo
运动状态
即先减速再加速以实现超车文中参考梯
形加速度 a控制策略23-24
8aM
aadj 分别为超车的最大加速度和调整加速度
8超车梯形加速度控制策略图
Fig. 8 Trapezoidal acceleration model of overtaking
Vf1 车恒速向前行驶
¨xVf1 = 0Vo
tlong 时刻达到相邻车道
对应的速度为 xotlong 此时
Vo车的纵向加速度可以表达为
¨xo=
xotlong xo0
tlong
ttlong
0
{
其他 19
按前述的分析Vo车通过碰撞点后将不发生任
何形式的碰撞通常情况下tctlong
结合式12
8所示的加速度控制策略VoVf1不发生碰撞
的条件为
Srt=Sr0¨xot2
2+xf1 xo0t
( )
> 0
20
将式19代入式20整理
Srt=Sr0+xf1 xo0) ) tt2
2t
( )
long
+xf1 xotlong) ) t2
2tlong
0
21
对应的临界安全车距为
min S
( (
= max xo0xf1tt2
2t
( )
long
+xf1xotlong ) ) t2
2t
)
long
)
0
22
xotlong xf1
- 2020m / sVo车与 Vf1
车的临界安全车距如图 9Vo车超车完成后的
车速 xtlong Vf1 车相对速度越小
安全距离
范围就越大与前面讨论相同
当车辆间的运动参数
朝箭头相反方
并超越安全临界线时
Vo车实施不安全超车行为
预警信号触发
9加速条件下 Vo车与 Vf1 车的安全距离区域
Fig. 9 Safety spacing regions between Voand Vf1 under the
condition of specific acceleration
4
驾驶员在超过程
需根据车速
车辆间距
车流状态以及道路交通设施等周边环境信息
实时
调整驾驶策略实现超车行为
在短暂的时间内完成
如此复杂的驾驶行为
驾驶员极可能产生误判
最终
使车辆处在潜在的碰撞危险之中为此
文中提出了
确保安全超车的预警算法首先分析了车辆超车安
全的影响因素然后对超车的碰撞形式进行分类
建立车辆超车的场景进而建立纵向安全距离的模
同时考虑车辆间车头时距
提出超车过程中车辆
碰撞的预警方法最后对算法进行仿真验证文中超
车碰撞的预警算法以临界安全距离为基础
兼顾驾
驶员主观特性
有较强的理论基础和工程实践价值
为汽车主动安全系统的研发和超车事故的预防奠定
了基础
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(下转第 98 )
29 华南理工大学学报(自然科学版)41
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Identification of Oversaturated Traffic Conditions Based on Loop Detection
Qian Zhe Xu Jian-min
School of Civil Engineering and TransportationSouth China University of TechnologyGuangzhou 510640GuangdongChina
AbstractThe identification of the oversaturted traffic conditions at the signal control intersection helps to control
traffic congestion. In the investigationbased on the detection data of inductive loop detectorsthe traffic wave theory
is utilized to identify the oversaturated traffic condition from two aspectsnamelythe retention queue length at the
end of the green light at an intersection and the overflow of the downstream intersection. Aiming at the first aspect
the queuing dissipated coefficient is defined to identify the oversaturated traffic condition at the intersection. Aiming
at the second aspectthe overflow retardation coefficient is defined to reveal the oversaturated overflow phenome-
non. Case study results show that oversaturated traffic condition can be accurately and effectively identified by cal-
culating the queue dissipation coefficient and the overflow retardation coefficient based on the loop detection data.
Key wordsoversaturated trafficstate identificationretention queueintersection overflowloop detection
(上接第 92 )
Warning Model for Safety Analysis of Overtaking Behavior Based on
Longitudinal Safety Spacing
You Feng1Zhang Rong-hui2Wang Hai-wei1Wen Hui-ying1Xu Jian-min1
1. School of Civil Engineering and TransportationSouth China University of TechnologyGuangzhou 510640GuangdongChina
2. Xinjiang Technical Institute of Physics & ChemistryChinese Academy of SciencesUrumqi 830011XinjiangChina
AbstractAt presentovertaking accidents on highway frequently occur with serious consequences. Aiming at this
problema warning model is proposed for preventing overtaking safety. Firstthe main factors influencing the safety
of overtaking are analyzed Nextovertaking collisions are categorized and overtaking scenario is developed. Then
by describing overtaking trajectories and by using a kinematic model of vehiclesa warning model of preventing o-
vertaking collisions is establishedwhich includes a critical longitudinal safety spacing model and a time-spa-cing
model. Finallythe effectiveness of the model is verified by using two instancesnamelyconstant-velocity
overtaking and specific-acceleration overtaking.
Key wordsintelligent vehicleovertakingsafetylongitudinal safety spacingtime-spacing model
89 华南理工大学学报(自然科学版)41
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