一种信号交叉口交通信号灯和车辆轨迹控制方法Traffic signal lamp and vehicle trajectory control method at signalized intersection
技术领域Technical field
本发明涉及智能网联汽车领域,尤其是涉及一种信号交叉口交通信号灯和车辆轨迹控制方法。The invention relates to the field of intelligent networked automobiles, in particular to a signalized intersection traffic signal lamp and a vehicle trajectory control method.
背景技术Background technique
随着交通需求的增加,近几年交通拥堵逐渐发展成世界级难题,造成严重的环境问题和经济损失。在城市交通运输网络中,交叉口通常被认为是交通流量的瓶颈。所以改善交叉口交通信号可以对城市交通系统的效率产生重大提升。With the increase in traffic demand, traffic congestion has gradually developed into a world-class problem in recent years, causing serious environmental problems and economic losses. In the urban transportation network, intersections are usually regarded as the bottleneck of traffic flow. Therefore, improving traffic signals at intersections can significantly improve the efficiency of urban transportation systems.
近几年随着智能网联技术的发展,车车通信(V2V)和车路通信(V2I)为交通控制提供了新的数据来源,同时随着自动驾驶技术的发展,车辆的控制为城市交通治理提供了新的解决方案。当下的交通控制方法集中于信号灯控制,对于车辆轨迹和信号灯配时的同时优化研究较少。In recent years, with the development of intelligent network technology, vehicle-to-vehicle communication (V2V) and vehicle-to-road communication (V2I) provide new data sources for traffic control. At the same time, with the development of autonomous driving technology, vehicle control is for urban traffic. Governance provides new solutions. The current traffic control methods focus on signal light control, and there is less research on the simultaneous optimization of vehicle trajectory and signal light timing.
发明内容Summary of the invention
本发明的目的就是为了克服上述现有技术存在的缺陷而提供一种信号交叉口交通信号灯和车辆轨迹控制方法。The purpose of the present invention is to provide a signalized intersection traffic signal lamp and a vehicle trajectory control method in order to overcome the above-mentioned defects in the prior art.
本发明的目的可以通过以下技术方案来实现:The purpose of the present invention can be achieved through the following technical solutions:
一种信号交叉口交通信号灯和车辆轨迹控制方法,该方法包括以下步骤:A method for controlling traffic signal lights and vehicle trajectories at signalized intersections. The method includes the following steps:
步骤S1:获取目标区域内的车辆信息;Step S1: Obtain vehicle information in the target area;
步骤S2:构建以最小化交叉口延迟为目标的混合整数线性规划模型,利用目标区域内的车辆信息求解混合整数线性规划模型,得到信号灯状态和车辆到达交叉口时刻
Step S2: Construct a mixed integer linear programming model with the goal of minimizing the intersection delay, and use the vehicle information in the target area to solve the mixed integer linear programming model to obtain the signal status and the time when the vehicle arrives at the intersection
步骤S3:构建车队头车轨迹最优控制模型,利用车辆到达交叉口时刻
求解车队头车轨迹最优控制模型,得到车队头车轨迹,构建车队跟驰车辆最优控制模型,利用车辆到达交叉口时刻
求解车队跟驰车辆最优控制模型,得到车队跟驰车辆轨迹;
Step S3: Construct an optimal control model for the trajectory of the lead vehicle of the fleet, using the time when the vehicle arrives at the intersection Solve the optimal control model of the lead vehicle trajectory of the fleet, obtain the trajectory of the lead vehicle of the fleet, construct the optimal control model of the fleet car-following vehicle, and use the time when the vehicle arrives at the intersection Solve the optimal control model of the car-following fleet and obtain the trajectory of the car-following fleet;
步骤S4:利用车队头车轨迹和车队跟驰车辆轨迹实现车辆轨迹控制,利用信号灯状态实现交通信号灯控制。Step S4: Use the trajectory of the leading vehicle of the fleet and the trajectory of the vehicle following the fleet to achieve vehicle trajectory control, and use the state of the signal light to achieve traffic signal light control.
所述的车辆信息包括车道编号和距离停车线距离。The vehicle information includes the lane number and the distance from the parking line.
所述的混合整数线性规划模型的目标函数为:The objective function of the mixed integer linear programming model is:
其中,α
1为所有车辆延迟的权重,α
2为周期时长的权重,i为交叉口方向索引,Ω
i为本次优化初始时刻t
0车道i的车辆集合,ω为车辆编号,
为轨迹变量T的子集,
为车辆的生成时间,
为车辆ω到达交叉口时刻,L
i为方向i目标区域长度,v
max为车辆最大速度,N为规划时域中的信号周期数,C
n为第n个信号周期的周期时长,V为控制变量的集合,S为信号灯信号序列的子集;
Wherein, α 1 is the weight of all vehicle retardation, α 2 is a long period when the weights, i is the index intersection direction, [Omega] i-oriented sub-optimal initial time t 0 i is set lane vehicle, [omega] is the vehicle number, Is a subset of the trajectory variable T, Is the generation time of the vehicle, Is the time when the vehicle ω arrives at the intersection, Li is the length of the target area in the direction i, v max is the maximum speed of the vehicle, N is the number of signal cycles in the planning time domain, C n is the cycle duration of the nth signal cycle, and V is the control A collection of variables, S is a subset of the signal sequence of the semaphore;
混合整数线性规划模型的约束条件包括车辆轨迹约束和信号灯约束,所述车辆轨迹约束包括允许占用车道约束、目标换道车道约束、换道行为约束、车间间距约束、车辆到达时间约束和不可变道区域约束,所述信号灯约束包括车道信号灯约束、绿灯开始时间约束、绿灯持续时间约束、绿灯结束时间约束、周期时长约束、清空时间约束、停车线约束和其他信号灯约束;The constraints of the mixed-integer linear programming model include vehicle trajectory constraints and signal lamp constraints. The vehicle trajectory constraints include allowable lane constraints, target lane-changing lane constraints, lane-changing behavior constraints, inter-vehicle spacing constraints, vehicle arrival time constraints, and immutable lanes. Area constraints, the signal light constraints include lane signal light constraints, green light start time constraints, green light duration constraints, green light end time constraints, cycle duration constraints, clear time constraints, stop line constraints, and other signal light constraints;
所述允许占用车道约束为:The allowable lane occupation constraint is:
其中,I为交叉口方向组成的集合,K每个进口道内车道集合,k为每个进口道内车道索引,车辆ω在车道k上时
为1,否则为0;
Among them, I is the set of intersection directions, K is the set of lanes in each entrance lane, k is the lane index in each entry lane, and when the vehicle ω is on lane k 1, otherwise 0;
目标换道车道约束为:The target lane change lane constraints are:
其中,I
A(x)为指示函数,当x∈A时I
A(x)=1,否则I
A(x)=0,K
i为方向i车道的集合,ω′为另一车辆,k'为另一车道,Ω
ω为本次优化初始时刻车辆ω前面的车辆集合,
为本次优化初始时刻车辆ω距离停车线距离,d
ω为距离参数,
为本次优化初始时刻车辆ω的速度,τ
ω为时间参数,M趋近无穷大,a
L为满足舒适度水平的最大减速度,本次优化初始时刻如果车辆ω在车道k上时
为1,否则为0;
Among them, I A (x) is the indicator function, when x ∈ A , I A (x) = 1, otherwise I A (x) = 0, K i is the set of lanes in the direction i, ω'is another vehicle, k 'Is another lane, Ω ω is the set of vehicles in front of vehicle ω at the initial moment of this optimization, For this optimization, the distance between the vehicle ω and the parking line at the initial moment, d ω is the distance parameter, For this optimization, the speed of the vehicle ω at the initial moment, τ ω is the time parameter, M approaches infinity, and a L is the maximum deceleration that meets the comfort level. At the initial time of this optimization, if the vehicle ω is on lane k 1, otherwise 0;
换道行为约束为:The lane change behavior is restricted as:
其中,K
ω为车辆ω可进入的车道集合,
为车辆ω上一次换道的时间,
为两次变道的最小时间间隔,如果车辆ω决定换道μ
ω为0,否则为1;
Among them, K ω is the set of lanes that the vehicle ω can enter, Is the last time the vehicle ω changed lanes, It is the minimum time interval between two lane changes, if the vehicle ω decides to change lanes, μ ω is 0, otherwise it is 1;
车间间距约束为:The workshop spacing constraints are:
其中,x
ω(t)为车辆ω在t时刻距离停车线距离,如果车辆ω和车辆ω′在同一车道η
ω,ω′为0,否则为1;
Among them, x ω (t) is the distance between the vehicle ω and the parking line at time t, if the vehicle ω and the vehicle ω'are in the same lane η ω, ω'is 0, otherwise it is 1;
车辆到达时间约束为:The vehicle arrival time constraints are:
其中,如果车辆ω保持上一步优化轨迹λ
ω为1,否则为0,
为车辆ω通过交叉口速度,
为本次优化初始时刻不可变道区域的车辆集合,a
U为满足舒适度水平的最大加速度,如果车辆不受其前方车辆影响γ
ω为0,否则为1,
为上一次优化车辆ω到达交叉口时刻,
为车辆ω从当前位置到达交叉口所需时间的上界,
为车辆ω从当前位置到达交叉口所需时间的下界,h
ω为车辆ω与前方车辆的车头时距,如果车辆ω不受其前方车辆影响ρ
ω,ω'为1,否则为0;
Among them, if the vehicle ω keeps the last optimized trajectory λ ω is 1, otherwise it is 0, Is the speed of the vehicle ω passing through the intersection, For this optimization, the set of vehicles in the immutable lane area at the initial moment, a U is the maximum acceleration that meets the comfort level, if the vehicle is not affected by the vehicle in front of it, γ ω is 0, otherwise it is 1. To optimize the time when the vehicle ω arrives at the intersection last time, Is the upper bound of the time required for the vehicle ω to reach the intersection from its current position, Is the lower bound of the time required for the vehicle ω to reach the intersection from its current position, h ω is the time distance between the vehicle ω and the front vehicle, if the vehicle ω is not affected by the vehicle in front of it, ρ ω,ω' is 1, otherwise it is 0;
不可变道区域约束为:The immutable track area constraints are:
车道信号灯约束为:The lane signal light constraints are:
其中,如果方向i的车道k被交通流(i,j)使用
为1,否则为0,
为交通流(i,j)在第n个信号周期的绿灯起始时间,
为交通流(i,j)在第n个信号周期的绿灯持续时间,
为交叉口方向i的车道k的绿灯起始时间,
为交叉口方向i的车道k的绿灯持续时间,Ψ为所有交通流的集合;
Among them, if lane k in direction i is used by traffic flow (i, j) Is 1, otherwise it is 0, Is the green light start time of traffic flow (i, j) in the nth signal period, Is the green light duration of the traffic flow (i, j) in the nth signal cycle, Is the start time of the green light for lane k in the intersection direction i, Is the green light duration of lane k in the intersection direction i, and Ψ is the set of all traffic flows;
绿灯开始时间约束为:The start time of the green light is restricted to:
其中,Ψ
0为本次优化初始时刻获得绿灯的交通流集合,
为当前周期的激活交通流(i,j)∈Ψ
0的绿灯启动时间,Ψ
p为本次优化初始时刻以前结束绿灯的交通流,t
S为当前周期的信号灯规划开始的时间;
Among them, Ψ 0 is the set of traffic flows that get the green light at the initial moment of this optimization, Is the green light start time of the active traffic flow (i, j) ∈ Ψ 0 in the current cycle, Ψ p is the traffic flow that ends the green light before the initial time of this optimization, and t S is the start time of the signal light planning of the current cycle;
绿灯持续时间约束为:The green light duration constraint is:
其中,
为交通流(i,j)的最小绿灯持续时间,
为当前周期的未激活交通流(i,j)∈Ψ
p的绿灯持续时间;
in, Is the minimum green light duration of traffic flow (i, j), Is the green light duration of the inactive traffic flow (i, j) ∈ Ψ p in the current cycle;
绿灯结束时间约束为:The green light end time constraint is:
周期时长约束为:The cycle length constraint is:
C
n≥t
0-t
s,n=1
C n ≥t 0 -t s , n=1
其中,Ψ
ic为冲突交通流的集合,在第n个信号周期若交通流(i,j)的绿灯开始时间在交通流(l,m)之后
为1,否则为0,在第n个信号周期若交通流(i,j)的绿灯开始时间在交通流(l,m)之前
为1,否则为0;
Among them, Ψ ic is the set of conflicting traffic flows. In the nth signal cycle, if the green light start time of the traffic flow (i, j) is after the traffic flow (l, m) 1, otherwise 0, if the green light start time of traffic flow (i, j) is before traffic flow (l, m) in the n-th signal cycle 1, otherwise 0;
清空时间约束为:The empty time constraint is:
其中,π
i,j,l,m为冲突交通流(i,j)和(l,m)的清空时间;
Among them, π i, j, l, m are the clearing time of conflicting traffic flows (i, j) and (l, m);
停车线约束为:The parking line constraints are:
其中,如果车辆ω在第n个信号周期经过交叉口
为1,否则为0;
Among them, if the vehicle ω passes the intersection in the nth signal cycle 1, otherwise 0;
其他信号灯约束为:Other semaphore constraints are:
其中,
为第n个信号周期交通流(i,j)和(l,m)绿灯启动时间的时间差,
为第n个信号周期交通流(i,j)和(l,m)绿灯结束时间的时间差。
in, Is the time difference between the green light activation time of the traffic flow (i, j) and (l, m) in the nth signal cycle, It is the time difference between the traffic flow (i, j) and the end time of the green light of (l, m) in the nth signal cycle.
车队头车轨迹最优控制模型分为头车在行驶时间内无法达到最高速度和头车在行驶时间内可以达到最高速度两种情况,所述头车在行驶时间内无法达到最高速度时满足:The optimal control model for the trajectory of the leader of the fleet is divided into two situations: the leader cannot reach the maximum speed during the driving time and the leader can reach the maximum speed during the driving time. When the leader cannot reach the maximum speed during the driving time, it meets:
其中,v
max为最大速度,
为车辆ω通过交叉口速度,
为本次优化初始时刻t
0车辆ω与停车线距离,a
L为满足舒适度水平的最大减速度,a
U为满足舒适度水平的最大加速度,
为本次优化初始时刻t
0车辆ω的速度;
Among them, v max is the maximum speed, Is the speed of the vehicle ω passing through the intersection, For this optimization, the distance between the vehicle ω and the parking line at the initial time t 0 is optimized, a L is the maximum deceleration that meets the comfort level, and a U is the maximum acceleration that meets the comfort level. Optimize the speed of the vehicle ω at the initial time t 0 for this time;
所述头车在行驶时间内可以达到最高速度时满足:When the leader vehicle can reach the maximum speed within the driving time, it meets the following requirements:
头车在行驶时间内无法达到最高速度时,所述的车队头车轨迹最优控制模型为:When the lead vehicle cannot reach the maximum speed during the driving time, the optimal control model for the trajectory of the lead vehicle in the fleet is:
其中,i
ω(t)为控制模型中车辆ω在t时刻的加速度,
为控制模型中车辆ω在t时刻的加速度,v
ω(t
0)为控制模型中车辆ω在本次优化初始时刻t
0的速度,v
ω(t)为车辆ω在t时刻的速度,a
ω(t)为车辆ω在t时刻的加速度,l
ω(t
0)为控制模型中车辆ω在本次优化初始时刻t
0的行进距离,
为控制模型中车辆ω在到达交叉口时刻的行进距离,
为控制模型中车辆ω在到达交叉口时刻的速度,
为采用最小加速度时的最小速度,
为采用最大加速度时的最大速度,Δt
ω为车辆ω到达交叉口的时间间隔。
Among them, i ω (t) is the acceleration of the vehicle ω in the control model at time t, Is the acceleration of the vehicle ω in the control model at time t, v ω (t 0 ) is the speed of the vehicle ω in the control model at the initial time t 0 of this optimization, v ω (t) is the speed of the vehicle ω at time t, a ω (t) is the acceleration of the vehicle ω at time t, and l ω (t 0 ) is the travel distance of the vehicle ω in the control model at the initial time t 0 of this optimization, In order to control the travel distance of the vehicle ω at the moment of arrival at the intersection in the model, To control the speed of the vehicle ω at the moment of arrival at the intersection in the model, To adopt the minimum speed at the minimum acceleration, In order to use the maximum speed at the maximum acceleration, Δt ω is the time interval for the vehicle ω to arrive at the intersection.
头车在行驶时间内可以达到最高速度时,所述的车队头车轨迹最优控制模型为:When the leader vehicle can reach the maximum speed within the driving time, the optimal control model for the trajectory of the leader vehicle in the fleet is:
其中,
表示当头车可以达到最高速度时车辆ω从当前位置到达交叉口所需时间的下界。
in, It represents the lower bound of the time required for the vehicle ω to reach the intersection from the current position when the leading vehicle can reach the maximum speed.
在规定时间内前车不会影响后车的轨迹时,所述的车队跟驰车辆最优控制模型为:When the preceding vehicle does not affect the trajectory of the following vehicle within the specified time, the optimal control model of the fleet-following vehicle is:
其中,i
ω(t)为控制模型中车辆ω在t时刻的加速度,
为控制模型中车辆ω在t时刻的加速度,v
ω(t
0)为控制模型中车辆ω在本次优化初始时刻t
0的速度,v
ω(t)为车辆ω在t时刻的速度,a
ω(t)为车辆ω在t时刻的加速度,l
ω(t
0)为控制模型中车辆ω在本次优化初始时刻t
0的行进距离,
为控制模型中车辆ω在到达交叉口时刻的行进距离,
为控制模型中车辆ω在到达交叉口时刻的速度,
为本次优化初始时刻t
0车辆ω与停车线距离,
为车辆ω通过交叉口速度,v
max为最大速度,a
L为满足舒适度水平的最大减速度,a
U为满足舒适度水平的最大加速度
为车辆ω从当前位置到达交叉口所需时间的上界,
为车辆ω从当前位置到达交叉口所需时间的下界,
表示当头车可以达到最高速度时车辆ω从当前位置到达交叉口所需时间的下界,Δt
ω为车辆ω到达交叉口的时间间隔。
Among them, i ω (t) is the acceleration of the vehicle ω in the control model at time t, Is the acceleration of the vehicle ω in the control model at time t, v ω (t 0 ) is the speed of the vehicle ω in the control model at the initial time t 0 of this optimization, v ω (t) is the speed of the vehicle ω at time t, a ω (t) is the acceleration of the vehicle ω at time t, and l ω (t 0 ) is the travel distance of the vehicle ω in the control model at the initial time t 0 of this optimization, In order to control the travel distance of the vehicle ω at the moment of arrival at the intersection in the model, To control the speed of the vehicle ω at the moment of arrival at the intersection in the model, The distance between the vehicle ω and the parking line at the initial time t 0 is optimized for this time, Is the speed of the vehicle ω passing through the intersection, v max is the maximum speed, a L is the maximum deceleration to meet the comfort level, and a U is the maximum acceleration to meet the comfort level Is the upper bound of the time required for the vehicle ω to reach the intersection from its current position, Is the lower bound of the time required for the vehicle ω to reach the intersection from its current position, It represents the lower bound of the time required for the vehicle ω to reach the intersection from the current position when the lead vehicle can reach the maximum speed, and Δt ω is the time interval for the vehicle ω to reach the intersection.
跟驰车辆在规定时间内跟驰前车时满足:When the car-following vehicle follows the preceding vehicle within the specified time:
其中,Δt为时间步长,Δx
U为行程距离的上界,x
ω(t)为车辆ω在t时刻与停车线距离,τ
ω为跟驰车辆在规定时间内跟驰前车时的时间参数,d
ω为跟驰车辆在规定时间内跟驰前车时的距离参数,x
ω’(t)为车辆ω'在t时刻与停车线距离。
Among them, Δt is the time step, Δx U is the upper bound of the travel distance, x ω (t) is the distance between the vehicle ω and the stop line at time t, and τ ω is the time when the car-following vehicle follows the preceding vehicle within the specified time Parameter, d ω is the distance parameter when the car following vehicle is following the preceding vehicle within a specified time, and x ω' (t) is the distance between the vehicle ω'and the stop line at time t.
所述的Δx
U为:
The Δx U is:
其中,Δt′=(v
max-v
ω(t))/a
U。
Among them, Δt'=(v max -v ω (t))/a U.
求解车辆轨迹的过程包括:The process of solving the vehicle trajectory includes:
步骤S31:若车辆本次优化到达交叉口时刻与上一次优化到达交叉口时刻相同,则车辆轨迹不变,执行步骤S35,否则,执行步骤S32;Step S31: If the vehicle's arrival time at the intersection during this optimization is the same as the time at which the vehicle arrived at the intersection during the last optimization, the vehicle trajectory remains unchanged, and step S35 is executed; otherwise, step S32 is executed;
步骤S32:判断是否为头车,若是,执行步骤S33,若否,执行步骤S34;Step S32: Determine whether it is the lead vehicle, if yes, execute step S33, if not, execute step S34;
步骤S33:分析头车在行驶时间内无法达到最高速度或头车在行驶时间内可以达到最高速度,分别通过对应的车队头车轨迹最优控制模型求解车队头车轨迹;Step S33: Analyze that the leader cannot reach the maximum speed during the driving time or the leader can reach the maximum speed during the driving time, and the trajectory of the leader of the fleet is solved through the corresponding optimal control model of the trajectory of the leader of the fleet;
步骤S34:分析跟驰车辆在规定时间内跟驰前车或规定时间内前车不会影响后车的轨迹,分别通过对应的车队跟驰车辆最优控制模型求解车队跟驰车辆轨迹;Step S34: Analyze the car-following vehicle following the preceding vehicle within the specified time or the preceding vehicle will not affect the trajectory of the following vehicle, and respectively solve the trajectory of the car-following vehicle through the corresponding optimal control model of the car-following vehicle;
步骤S35:得到车辆轨迹。Step S35: Obtain the vehicle trajectory.
与现有技术相比,本发明具有以下优点:Compared with the prior art, the present invention has the following advantages:
(1)通过建立一个混合整数线性规划模型和控制模型实现在智能网联环境下同时对信号交叉口的车辆轨迹和交通信号灯进行同时优化,从而使对信号灯和车辆轨迹控制更加精确。(1) By establishing a mixed-integer linear programming model and a control model, the vehicle trajectory and traffic lights at signalized intersections can be optimized simultaneously in an intelligent network environment, so that the control of the traffic lights and vehicle trajectories can be more accurate.
(2)具有实时控制的能力,可以实现对交叉口内100辆以上车辆和每个车道上的信号灯实现实时控制。(2) It has the ability of real-time control, which can realize real-time control of more than 100 vehicles in the intersection and the signal lights on each lane.
(3)相比于现有的感应控制可以实现提升交叉口通行能力约50%,降低延误超过80%。(3) Compared with the existing induction control, the traffic capacity of the intersection can be increased by about 50%, and the delay can be reduced by more than 80%.
附图说明Description of the drawings
图1为本发明的流程图;Figure 1 is a flow chart of the present invention;
图2为本发明车队头车分类;Figure 2 is the classification of the leader of the fleet of the invention;
图3为本发明车队跟驰车辆分类。Figure 3 shows the classification of the car-following vehicle fleet of the present invention.
具体实施方式Detailed ways
下面结合附图和具体实施例对本发明进行详细说明。本实施例以本发明技术方案为前提进行实施,给出了详细的实施方式和具体的操作过程,但本发明的保护范围不限于下述的实施例。The present invention will be described in detail below with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and provides detailed implementation and specific operation procedures, but the protection scope of the present invention is not limited to the following embodiments.
实施例Example
本实施例提供一种信号交叉口交通信号灯和车辆轨迹控制方法,如图1所示,包括以下步骤:This embodiment provides a method for controlling traffic lights and vehicle trajectories at signalized intersections, as shown in FIG. 1, including the following steps:
步骤S1:获取目标区域内的车辆信息;Step S1: Obtain vehicle information in the target area;
步骤S2:构建以最小化交叉口延迟为目标的混合整数线性规划模型,利用目标区域内的车辆信息求解混合整数线性规划模型,得到信号灯状态和车辆到达交叉口时刻
Step S2: Construct a mixed integer linear programming model with the goal of minimizing the intersection delay, and use the vehicle information in the target area to solve the mixed integer linear programming model to obtain the signal status and the time when the vehicle arrives at the intersection
步骤S3:构建车队头车轨迹最优控制模型,利用车辆到达交叉口时刻
求解车队头车轨迹最优控制模型,得到车队头车轨迹;构建车队跟驰车辆最优控制模型,利用车辆到达交叉口时刻
求解车队跟驰车辆最优控制模型,得到车队跟驰车辆轨迹;
Step S3: Construct an optimal control model for the trajectory of the lead vehicle of the fleet, using the time when the vehicle arrives at the intersection Solve the optimal control model of the lead vehicle trajectory of the fleet, and obtain the trajectory of the lead vehicle of the fleet; construct the optimal control model of the fleet following vehicles, and use the time when the vehicles arrive at the intersection Solve the optimal control model of the car-following fleet and obtain the trajectory of the car-following fleet;
步骤S4:利用车队头车轨迹和车队跟驰车辆轨迹实现车辆轨迹控制,利用信号灯状态实现交通信号灯控制。Step S4: Use the trajectory of the leading vehicle of the fleet and the trajectory of the vehicle following the fleet to achieve vehicle trajectory control, and use the state of the signal light to achieve traffic signal light control.
具体而言:in particular:
车辆信息包括车道编号和距离停车线距离,车辆轨迹为车辆每一时刻的位置、速度和加速度,信号灯状态包括交叉口内每个车道的信号灯相位相序和相位时长(每个车道的行车规则受每个车道之上的信号灯单独控制)。The vehicle information includes the lane number and the distance from the stop line. The vehicle trajectory is the position, speed and acceleration of the vehicle at each moment. The signal light state includes the signal light phase sequence and phase duration of each lane in the intersection (the driving rules of each lane are subject to each The signal lights above each lane are individually controlled).
混合整数线性规划模型的目标函数为:The objective function of the mixed integer linear programming model is:
其中,α
1为所有车辆延迟的权重,α
2为周期时长的权重,i为交叉口方向索引,Ω
i为本次优化初始时刻t
0车道i的车辆集合,ω为车辆编号,
为轨迹变量T的子集,
为车辆的生成时间,
为车辆ω到达交叉口时刻,L
i为方向i目标区域长度,v
max为车辆最大速度,N为规划时域中的信号周期数,C
n为第n个信号周期的周期时长,V为控制变量的集合,S为信号灯信号序列的子集。
Wherein, α 1 is the weight of all vehicle retardation, α 2 is a long period when the weights, i is the index intersection direction, [Omega] i-oriented sub-optimal initial time t 0 i is set lane vehicle, [omega] is the vehicle number, Is a subset of the trajectory variable T, Is the generation time of the vehicle, Is the time when the vehicle ω arrives at the intersection, Li is the length of the target area in the direction i, v max is the maximum speed of the vehicle, N is the number of signal cycles in the planning time domain, C n is the cycle duration of the nth signal cycle, and V is the control The set of variables, S is a subset of the signal sequence of the semaphore.
选择合理的α
1,α
2的判别标准为:
Choose a reasonable α 1 , the criterion of α 2 is:
其中,
为令α
1=1、α
2=0解得的混合整数线性规划模型的目标值,Δd为目标值下降的最小单元。
in, In order to make α 1 =1 and α 2 =0 to solve the target value of the mixed integer linear programming model, Δd is the minimum unit for the decrease of the target value.
混合整数线性规划模型的约束条件包括车辆轨迹约束和信号灯约束,所述车辆轨迹约束包括允许占用车道约束、目标换道车道约束、换道行为约束、车间间距约束、车辆到达时间约束和不可变道区域约束,所述信号灯约束包括车道信号灯约束、绿灯开始时间约束、绿灯持续时间约束、绿灯结束时间约束、周期时长约束、清空时间约束、停车线约束和其他信号灯约束;The constraints of the mixed-integer linear programming model include vehicle trajectory constraints and signal lamp constraints. The vehicle trajectory constraints include allowable lane constraints, target lane-changing lane constraints, lane-changing behavior constraints, inter-vehicle spacing constraints, vehicle arrival time constraints, and immutable lanes. Area constraints, the signal light constraints include lane signal light constraints, green light start time constraints, green light duration constraints, green light end time constraints, cycle duration constraints, clear time constraints, stop line constraints, and other signal light constraints;
允许占用车道约束为:The allowable lane occupation constraints are:
其中,I为交叉口方向组成的集合,K每个进口道内车道集合,k为每个进口道内车道索引,车辆ω在车道k上时
为1,否则为0;
Among them, I is the set of intersection directions, K is the set of lanes in each entrance lane, k is the lane index in each entry lane, and when the vehicle ω is on lane k 1, otherwise 0;
目标换道车道约束为:The target lane change lane constraints are:
其中,I
A(x)为指示函数,当x∈A时I
A(x)=1,否则I
A(x)=0,K
i为方向i车道的集合,ω′为另一车辆,k'为另一车道,Ω
ω为本次优化初始时刻车辆ω前面的车辆集合,
为本次优化初始时刻车辆ω距离停车线距离,d
ω为距离参数,τ
ω为时间参数,
为本次优化初始时刻车辆ω的速度,M趋近无穷大,a
L为满足舒适度水平的最大减速度,本次优化初始时刻如果车辆ω在车道k上时
为1,否则为0;
Among them, I A (x) is the indicator function, when x ∈ A , I A (x) = 1, otherwise I A (x) = 0, K i is the set of lanes in the direction i, ω'is another vehicle, k 'Is another lane, Ω ω is the set of vehicles in front of vehicle ω at the initial moment of this optimization, For this optimization, the distance between the vehicle ω and the parking line at the initial moment, d ω is the distance parameter, and τ ω is the time parameter. In this optimization, the speed of the vehicle ω at the initial moment, M approaches infinity, and a L is the maximum deceleration that satisfies the comfort level. At the initial moment of this optimization, if the vehicle ω is in lane k 1, otherwise 0;
换道行为约束为:The lane change behavior is restricted as:
其中,K
ω为车辆ω可进入的车道集合,
为车辆ω上一次换道的时间,
为两次变道的最小时间间隔,如果车辆ω决定换道μ
ω为0,否则为1;
Among them, K ω is the set of lanes that the vehicle ω can enter, Is the last time the vehicle ω changed lanes, It is the minimum time interval between two lane changes, if the vehicle ω decides to change lanes, μ ω is 0, otherwise it is 1;
车间间距约束为:The workshop spacing constraints are:
其中,x
ω(t)为车辆ω在t时刻距离停车线距离,如果车辆ω和车辆ω′在同一车道η
ω,ω′为0,否则为1;
Among them, x ω (t) is the distance between the vehicle ω and the parking line at time t, if the vehicle ω and the vehicle ω'are in the same lane η ω, ω'is 0, otherwise it is 1;
车辆到达时间约束为:The vehicle arrival time constraints are:
其中,如果车辆ω保持上一步优化轨迹λ
ω为1,否则为0,
为车辆ω通过交叉口速度,
为本次优化初始时刻不可变道区域的车辆集合,a
U为满足舒适度水平的最大加速度,如果车辆不受其前方车辆影响γ
ω为0,否则为1,
为上一次优化车辆ω到达交叉口时刻,
为车辆ω从当前位置到达交叉口所需时间的上界,
为车辆ω从当前位置到达交叉口所需时间的下界,h
ω为车辆ω与前方车辆的车头时距,如果车辆ω不受其前方车辆影响ρ
ω,ω'为1,否则为0;
Among them, if the vehicle ω keeps the last optimized trajectory λ ω is 1, otherwise it is 0, Is the speed of the vehicle ω passing through the intersection, For this optimization, the set of vehicles in the immutable lane area at the initial moment, a U is the maximum acceleration that meets the comfort level, if the vehicle is not affected by the vehicle in front of it, γ ω is 0, otherwise it is 1. To optimize the time when the vehicle ω arrives at the intersection last time, Is the upper bound of the time required for the vehicle ω to reach the intersection from its current position, Is the lower bound of the time required for the vehicle ω to reach the intersection from its current position, h ω is the time distance between the vehicle ω and the front vehicle, if the vehicle ω is not affected by the vehicle in front of it, ρ ω,ω' is 1, otherwise it is 0;
不可变道区域约束为:The immutable track area constraints are:
车道信号灯约束为:The lane signal light constraints are:
其中,如果方向i的车道k被交通流(i,j)使用
为1,否则为0,
为交通流(i,j)在第n个信号周期的绿灯起始时间,
为交通流(i,j)在第n个信号周期的绿灯持续时间,
为交叉口方向i的车道k的绿灯起始时间,
为交叉口方向i的车道k的绿灯持续时间,Ψ为所有交通流的集合;
Among them, if lane k in direction i is used by traffic flow (i, j) Is 1, otherwise it is 0, Is the green light start time of traffic flow (i, j) in the nth signal period, Is the green light duration of the traffic flow (i, j) in the nth signal cycle, Is the start time of the green light for lane k in the intersection direction i, Is the green light duration of lane k in the intersection direction i, and Ψ is the set of all traffic flows;
绿灯开始时间约束为:The start time of the green light is restricted to:
其中,Ψ
0为本次优化初始时刻获得绿灯的交通流集合,
为当前周期的激活交通流(i,j)∈Ψ
0的绿灯启动时间,Ψ
p为本次优化初始时刻以前结束绿灯的交通流,t
S为当前周期的信号灯规划开始的时间;
Among them, Ψ 0 is the set of traffic flows that get the green light at the initial moment of this optimization, Is the green light start time of the active traffic flow (i, j) ∈ Ψ 0 in the current cycle, Ψ p is the traffic flow that ends the green light before the initial time of this optimization, and t S is the start time of the signal light planning of the current cycle;
绿灯持续时间约束为:The green light duration constraint is:
其中,
为交通流(i,j)的最小绿灯持续时间,
为当前周期的未激活交通流(i,j)∈Ψ
p的绿灯持续时间;
in, Is the minimum green light duration of traffic flow (i, j), Is the green light duration of the inactive traffic flow (i, j) ∈ Ψ p in the current cycle;
绿灯结束时间约束为:The green light end time constraint is:
周期时长约束为:The cycle length constraint is:
C
n≥t
0-t
s,n=1
C n ≥t 0 -t s , n=1
其中,Ψ
ic为冲突交通流的集合,在第n个信号周期若交通流(i,j)的绿灯开始时间在交通流(l,m)之后
为1,否则为0,在第n个信号周期若交通流(i,j)的绿灯开始时间在交通流(l,m)之前
为1,否则为0;
Among them, Ψ ic is the set of conflicting traffic flows. In the nth signal cycle, if the green light start time of the traffic flow (i, j) is after the traffic flow (l, m) 1, otherwise 0, if the green light start time of traffic flow (i, j) is before traffic flow (l, m) in the n-th signal cycle 1, otherwise 0;
清空时间约束为:The empty time constraint is:
其中,π
i,j,l,m为冲突交通流(i,j)和(l,m)的清空时间;
Among them, π i, j, l, m are the clearing time of conflicting traffic flows (i, j) and (l, m);
停车线约束为:The parking line constraints are:
其中,如果车辆ω在第n个信号周期经过交叉口
为1,否则为0;
Among them, if the vehicle ω passes the intersection in the nth signal cycle 1, otherwise 0;
其他信号灯约束为:Other semaphore constraints are:
其中,
为第n个信号周期交通流(i,j)和(l,m)绿灯启动时间的时间差,
为第n个信号周期交通流(i,j)和(l,m)绿灯结束时间的时间差。
in, Is the time difference between the green light activation time of the traffic flow (i, j) and (l, m) in the nth signal cycle, It is the time difference between the traffic flow (i, j) and the end time of the green light of (l, m) in the nth signal cycle.
车队头车轨迹最优控制模型和车队跟驰车辆最优控制模型统称为车辆轨迹控制模型,车辆轨迹控制模型目的是在规定车辆到达交叉口时刻的条件下,确定车辆每一时刻的轨迹(位置、速度和加速度),车队的判别标准为在同一个信号相位同一个车道内通过交叉口的车辆。The optimal control model for the trajectory of the team leader and the optimal control model for the following vehicles are collectively referred to as the vehicle trajectory control model. The purpose of the vehicle trajectory control model is to determine the trajectory (position , Speed and acceleration), the judging standard of the fleet is the vehicles passing the intersection in the same signal phase and the same lane.
车队头车轨迹最优控制模型分为头车在行驶时间内无法达到最高速度和头车在行驶时间内可以达到最高速度两种情况,如图2所示,头车在行驶时间内无法达到最高速度时满足:The optimal control model for the trajectory of the lead vehicle in the fleet is divided into two situations: the lead vehicle cannot reach the maximum speed during the driving time and the lead vehicle can reach the maximum speed during the driving time. As shown in Figure 2, the leader cannot reach the maximum speed during the driving time. Meet the speed:
其中,v
max为最大速度,
为车辆ω通过交叉口速度,
为本次优化初始时刻t
0车辆ω与停车线距离,a
L为满足舒适度水平的最大减速度,a
U为满足舒适度水平的最大加速度,
为本次优化初始时刻t
0车辆ω的速度。
Among them, v max is the maximum speed, Is the speed of the vehicle ω passing through the intersection, For this optimization, the distance between the vehicle ω and the parking line at the initial time t 0 is optimized, a L is the maximum deceleration that meets the comfort level, and a U is the maximum acceleration that meets the comfort level. The speed of the vehicle ω at the initial time t 0 is optimized for this time.
头车在行驶时间内可以达到最高速度时满足:When the lead vehicle can reach the maximum speed within the driving time, it meets the following requirements:
头车在行驶时间内无法达到最高速度时,车队头车轨迹最优控制模型为:When the lead vehicle cannot reach the maximum speed during the driving time, the optimal control model for the trajectory of the lead vehicle in the fleet is:
其中,i
ω(t)为控制模型中车辆ω在t时刻的加速度,
为控制模型中车辆ω在t时刻的加速度,v
ω(t
0)为控制模型中车辆ω在本次优化初始时刻t
0的速度,v
ω(t)为车辆ω在t时刻的速度,a
ω(t)为车辆ω在t时刻的加速度,l
ω(t
0)为控制模型中车辆ω在本次优化初始时刻t
0的行进距离,
为控制模型中车辆ω在到达交叉口时刻的行进距离,
为控制模型中车辆ω在到达交叉口时刻的速度,
为采用最小加速度时的最小速度,
为采用最大加速度时的最大速度,Δt
ω为车辆ω到达交叉口的时间间隔。
Among them, i ω (t) is the acceleration of the vehicle ω in the control model at time t, Is the acceleration of the vehicle ω in the control model at time t, v ω (t 0 ) is the speed of the vehicle ω in the control model at the initial time t 0 of this optimization, v ω (t) is the speed of the vehicle ω at time t, a ω (t) is the acceleration of the vehicle ω at time t, and l ω (t 0 ) is the travel distance of the vehicle ω in the control model at the initial time t 0 of this optimization, In order to control the travel distance of the vehicle ω at the moment of arrival at the intersection in the model, To control the speed of the vehicle ω at the moment of arrival at the intersection in the model, To adopt the minimum speed at the minimum acceleration, In order to use the maximum speed at the maximum acceleration, Δt ω is the time interval for the vehicle ω to arrive at the intersection.
头车在行驶时间内可以达到最高速度时,车队头车轨迹最优控制模型为:When the leader vehicle can reach the maximum speed within the driving time, the optimal control model for the trajectory of the leader vehicle in the fleet is:
其中,
表示当头车可以达到最高速度时车辆ω从当前位置到达交叉口所需时间的下界。
in, It represents the lower bound of the time required for the vehicle ω to reach the intersection from the current position when the leading vehicle can reach the maximum speed.
车队跟驰车辆可以分成两种,如图3所示,在规定时间内前车不会影响后车的轨迹时,则后车开得越快越好,车队跟驰车辆最优控制模型为:The car-following vehicle fleet can be divided into two types. As shown in Figure 3, when the preceding vehicle will not affect the trajectory of the following car within the specified time, the faster the following car drives, the better. The optimal control model of the car-following vehicle fleet is:
其中,i
ω(t)为控制模型中车辆ω在t时刻的加速度,
为控制模型中车辆ω在t时刻的加速度,v
ω(t
0)为控制模型中车辆ω在本次优化初始时刻t
0的速度,v
ω(t)为车辆ω在t时刻的速度,a
ω(t)为车辆ω在t时刻的加速度,l
ω(t
0)为控制模型中车辆ω在本次优化初始时刻t
0的行进距离,
为控制模型中车辆ω在到达交叉口时刻的行进距离,
为控制模型中车辆ω在到达交叉口时刻的速度,
为本次优化初始时刻t
0车辆ω与停车线距离,
为车辆ω通过交叉口速度,v
max为最大速度,a
L为满足舒适度水平的最大减速度,a
U为满足舒适度水平的最大加速度。
Among them, i ω (t) is the acceleration of the vehicle ω in the control model at time t, Is the acceleration of the vehicle ω in the control model at time t, v ω (t 0 ) is the speed of the vehicle ω in the control model at the initial time t 0 of this optimization, v ω (t) is the speed of the vehicle ω at time t, a ω (t) is the acceleration of the vehicle ω at time t, and l ω (t 0 ) is the travel distance of the vehicle ω in the control model at the initial time t 0 of this optimization, In order to control the travel distance of the vehicle ω at the moment of arrival at the intersection in the model, To control the speed of the vehicle ω at the moment of arrival at the intersection in the model, The distance between the vehicle ω and the parking line at the initial time t 0 is optimized for this time, Is the speed of the vehicle ω passing through the intersection, v max is the maximum speed, a L is the maximum deceleration that meets the comfort level, and a U is the maximum acceleration that meets the comfort level.
跟驰车辆在规定时间内跟驰前车时,服从Newell一阶线性跟车模型,即每个时刻的位置满足:When the car-following vehicle follows the preceding vehicle within the specified time, it obeys the Newell first-order linear car-following model, that is, the position at each moment satisfies:
其中,Δt为时间步长,Δx
U为行程距离的上界,x
ω(t)为车辆ω在t时刻与停车线距离,τ
ω为跟驰车辆在规定时间内跟驰前车时的时间参数,d
ω为跟驰车辆在规定时间内跟驰前车时的距离参数,x
ω’(t)为车辆ω'在t时刻与停车线距离,Δx
U为:
Among them, Δt is the time step, Δx U is the upper bound of the travel distance, x ω (t) is the distance between the vehicle ω and the stop line at time t, and τ ω is the time when the car-following vehicle follows the preceding vehicle within the specified time Parameters, d ω is the distance parameter when the car-following vehicle follows the preceding vehicle within the specified time, x ω' (t) is the distance between the vehicle ω'and the stop line at time t, and Δx U is:
其中,Δt′=(v
max-v
ω(t))/a
U,这样保证了跟驰车辆满足如下车间时距h
ω和到达时刻
的关系:
Among them, Δt′=(v max -v ω (t))/a U , which ensures that the car-following vehicle satisfies the following inter-vehicle time distance h ω and arrival time Relationship:
求解车辆轨迹的过程包括:The process of solving the vehicle trajectory includes:
步骤S31:若车辆本次优化到达交叉口时刻与上一次优化到达交叉口时刻相同,则车辆轨迹不变,执行步骤S35,否则,执行步骤S32;Step S31: If the vehicle's arrival time at the intersection during this optimization is the same as the time at which the vehicle arrived at the intersection during the last optimization, the vehicle trajectory remains unchanged, and step S35 is executed; otherwise, step S32 is executed;
步骤S32:判断是否为头车,若是,执行步骤S33,若否,执行步骤S34;Step S32: Determine whether it is the lead vehicle, if yes, execute step S33, if not, execute step S34;
步骤S33:分析头车在行驶时间内无法达到最高速度或头车在行驶时间内可以达到最高速度,分别通过对应的车队头车轨迹最优控制模型求解车队头车轨迹;Step S33: Analyze that the leader cannot reach the maximum speed during the driving time or the leader can reach the maximum speed during the driving time, and the trajectory of the leader of the fleet is solved through the corresponding optimal control model of the trajectory of the leader of the fleet;
步骤S34:分析跟驰车辆在规定时间内跟驰前车或规定时间内前车不会影响后车的轨迹,分别通过对应的车队跟驰车辆最优控制模型求解车队跟驰车辆轨迹;Step S34: Analyze the car-following vehicle following the preceding vehicle within the specified time or the preceding vehicle will not affect the trajectory of the following vehicle, and respectively solve the trajectory of the car-following vehicle through the corresponding optimal control model of the car-following vehicle;
步骤S35:得到车辆轨迹。Step S35: Obtain the vehicle trajectory.
涉及的部分参数解释如表1。Some parameters involved are explained in Table 1.
表1 部分参数解释Table 1 Explanation of some parameters
以下为一具体例子:The following is a specific example:
在SUMO(一款众所周知的开源微观仿真软件)中搭建了测试实例,设置具有四个方向进口道的交叉口,设置1、3进口道(南北对向)最大绿灯时间为30s,2、4进口道(东西对向)最大绿灯时间20s,最小绿灯时间为2s,设置仿真时间1200s,同时算法时间间隔与仿真时间步长均为1s。将感应控制(现实中智能交叉口常用信号灯控制方法)与本实施例方法进行对比,在不同交通流量条件下,本实例方法均能有效提高通行能力,其中最高可达50%。A test case was built in SUMO (a well-known open source micro-simulation software), an intersection with entrance lanes in four directions was set, and the maximum green time for entrances 1, 3 (north-south facing) was set to 30s, and entrances 2, 4 The maximum green light time for the road (east-west facing) is 20s, the minimum green light time is 2s, and the simulation time is set to 1200s. At the same time, the algorithm time interval and the simulation time step are both 1s. Comparing the induction control (commonly used signal light control method for intelligent intersections in reality) with the method of this embodiment, the method of this embodiment can effectively improve the traffic capacity under different traffic flow conditions, of which up to 50%.