CN104332058B - A kind of Intelligent traffic light control method and system - Google Patents

Abstract

The invention discloses an intelligent traffic light control system, which includes a monitoring camera, traffic signal lights and countdown lights, and also includes a microprocessor for detecting traffic flow at intersections, a microprocessor for automatically adjusting and calculating traffic signal timing, a display drive module, and a digital image processing system. The controller and I/O interface, the controller automatically adjusts the signal timing of traffic lights, so that the utilization rate of green lights in all directions at the intersection increases or decreases according to the same trend compared with traffic vehicles, effectively and dynamically recognizes the traffic conditions at the intersection, and automatically Adjust signal timing to reduce congestion.

Description

An intelligent traffic light control method and system

technical field

The invention relates to the traffic field, in particular to an intelligent traffic light controller in the traffic field.

Background technique

At present, the urban traffic situation in major large and medium-sized cities in my country is not optimistic. There are many vehicles, road congestion, and serious vehicle exhaust pollution. These have become an important factor restricting social and economic development to some extent. According to the research results of experts from the Sustainable Development Strategy Research Group of the Chinese Academy of Sciences, 15 cities in China lose nearly 1 billion yuan in wealth every day due to traffic congestion and management problems. In addition, congested traffic can easily cause bad psychological emotions of drivers and increase the probability of traffic accidents.

The use of advanced technology is an effective way to solve the current urban traffic dilemma. With the help of advanced technology, the potential of existing traffic facilities can be fully tapped, and the limited traffic resources can be used to transport as many people and objects as possible to solve the traffic demand. The contradiction between constant growth and lack of transportation resources. One application that has an immediate effect in solving urban traffic congestion is to install smart traffic lights at road level intersections to replace traditional traffic lights. Traditional traffic lights use a fixed signal period and green signal ratio, which cannot be automatically adjusted according to the dynamic changes in traffic flow at intersections. There are often situations where the green light at intersections with many vehicles has a short transit time, and intersections with no or few vehicles have green lights. Intersection capacity is wasted. The intelligent traffic lights can dynamically adjust the parameters of the traffic lights according to the real-time changes of the traffic flow at the intersection, so that the waiting time of the vehicles passing the intersection is greatly shortened, and the traffic efficiency of the intersection is improved.

Although intelligent traffic lights have such attractive advantages, researchers have also carried out research on this and designed some intelligent traffic light control schemes, but at this stage, it has not been widely used. The main reason is that The existing intelligent traffic light control method needs to detect the number of vehicles waiting in the direction of the intersection in real time, which requires two vehicle detectors to be installed at two places separated by a certain distance behind the stop line of each lane, and the detected vehicle data Transmission to the traffic signal controller requires a large amount of installation work, which will affect the traffic of the construction section, and may damage the existing road surface, requiring a large amount of capital investment. Vehicle detectors mainly include ultrasonic, infrared, microwave radar, ground sense coil and other types. Each type of detector has its own advantages and disadvantages, and there is no uniform standard for its selection. The above-mentioned factors make it difficult for the traffic management department to make up their minds and uniformly install intelligent traffic light controllers at intersections.

Aiming at the above-mentioned difficulties, the present invention discloses a scheme of intelligent traffic lights at level intersections. Its core idea is to make full use of the existing hardware equipment at the intersection, only need to replace the traffic signal controller, and connect the high-definition camera video signal at the intersection at the same time, using the corresponding Image processing and traffic light signal duration dynamic adjustment algorithm to realize the dynamic adjustment of signal lights. Its transformation only involves replacing the traffic signal control machine and connecting the video signal of the intersection camera, which can be carried out around the control box on the roadside without blocking the traffic. Moreover, the installation and commissioning time is very short, and night construction is optional. Or during construction during the day, use mobile traffic lights to temporarily manage intersection traffic. The transformation process is convenient and fast, and the equipment cost is small.

Contents of the invention

An intelligent traffic light control scheme, using the existing surveillance cameras at road level intersections to collect video information of traffic conditions at the intersection, and using image processing algorithms to obtain traffic flow data in all directions at the intersection. The controller automatically adjusts the signal timing of the traffic lights according to the data and the set algorithm, so that the green light utilization rate in each direction of the intersection increases or decreases in the same trend as compared with the traffic vehicles. The specific scheme of the present invention is as follows:

An intelligent traffic light control system is provided, including a monitoring camera, traffic signal lights and countdown lights. Device, I/O interface:

The monitoring camera sends the obtained video to the digital image processor, and the digital image processor performs image processing and outputs the processing result to the intersection traffic flow detection microprocessor, and the intersection traffic flow detection microprocessor obtains the traffic flow information and Transmitting to the traffic signal timing automatic adjustment calculation microprocessor, after the traffic signal timing automatic adjustment calculation microprocessor obtains the signal timing result after processing, calls the I/O interface and display driver module, and outputs the signal timing result To traffic lights and countdown lights.

Described intersection traffic flow detection microprocessor adopts following steps to obtain traffic flow information:

A) Identify the number and type of vehicles passing through each direction of the intersection within one signal cycle of the traffic light;

B) Calculate the equivalent number of small cars according to the length ratio of large cars and small cars;

C) Divide this number by the number of lanes in this direction at the intersection to obtain the traffic flow n _i of each lane in this direction.

The automatic adjustment calculation microprocessor (4) of the traffic signal timing adjusts the signal timing of the traffic lights in the following way:

A) Note that the two directions of the intersection are x and y respectively, and the signal period of the traffic signal light is t, which contains four phases, which are respectively going straight in the x direction, turning left in the x direction, going straight in the y direction, and turning left in the y direction. The time lengths are t ₁ , t ₂ , t ₃ and t ₄ respectively, then formula (1) is obtained:

t=t ₁ +t ₂ +t ₃ +t ₄ (1)

B) Assuming that the average traffic flow of a single lane during each phase is n ₁ , n ₂ , n ₃ and n ₄ , and the green light utilization rate η is defined as the ratio of the traffic flow of a single lane to the green light duration, then each green light phase The utilization rate of the green light duration is

(2)

The average utilization of the green light duration at the intersection is

(3)

In general, the above utilization ratios are not equal, that is,

(4)

C) At the end of a signal period, the measured traffic parameters during the signal period are t _i , (i=1,2,3,4) and Then the basic signal duration t _i ', (i=1,2,3,4) of each phase of the next signal cycle is

(5)

The relationship between t _i ' and t _i satisfies

(6)

D) According to the actual situation of the intersection, each phase has a corresponding minimum green light time, which is recorded as t _gmin . According to the comparison result of t _i ' and t _gmin above, the setting of each signal duration in the next signal cycle is considered in two cases:

(1) t _i '3t _gmin ,(i=1,2,3,4)

Taking t _i ' as the signal duration of each phase in the next signal cycle, the new signal cycle time remains unchanged, and the expected value of the green light utilization rate of each phase is the same, both

(2) At least one phase j,j∈{1,2,3,4} exists, satisfying t' _j <t _gmin

Adjust the value of t _i ' that is smaller than t _gmin to t _gmin , and the borrowed time is evenly distributed to other phases. For this, first sort t _i ' (i=1,2,3,4) from small to large , the new sequence is denoted as s _i , according to the relationship between s _i and t _gmin , make corresponding adjustments.

Rationale for technical solutions

1. Overall structure

The intelligent traffic light controller described in this method includes modules such as traffic flow detection at intersections, automatic adjustment and calculation of traffic signal timing, and display drive. The overall framework is shown in Figure 1 of the specification. The camera in the picture uses the intersection monitoring camera, no additional installation is required; the DSP (digital image processing) processor and the intersection traffic flow detection microprocessor calculate the traffic flow according to the image information and automatically adjust the calculation microprocessor for traffic signal matching; the microprocessor The processor executes the signal timing automatic adjustment algorithm described in the present invention, drives the traffic lights and countdown lights at the intersection, and is provided with corresponding I/O ports.

2. Traffic flow detection

Commonly used traffic flow detection methods include ground sensing coils, ultrasonic waves, microwaves, and video technologies. In the technical solution, the vehicle flow detection device makes full use of the existing equipment at the intersection to reduce cost and installation difficulty. Considering that the main intersections of urban roads are equipped with surveillance cameras, this method uses video traffic flow detection technology, and uses image processing algorithms to obtain traffic flow information with the help of cameras installed at intersections. The image processing function is completed on a specially designed digital image processing (DSP) circuit board, which receives the intersection video signal, performs image processing, obtains traffic flow information, and transmits it to the microprocessor.

In image processing, the number and type of vehicles passing through the intersection in each direction within one signal period of the traffic lights are first identified; secondly, the equivalent number of small cars is converted according to the length ratio of large cars and small cars; finally, the number is divided by Based on the number of lanes in this direction at the intersection, the traffic flow n _i of each lane in this direction is obtained.

3. Signal timing automatic adjustment method

Taking the most common cross-shaped intersection as an example, record the two directions of the intersection as x and y, and set the signal period of the traffic light as t, including four phases, which are straight ahead in x direction and left turn in x direction , go straight in the y direction, and turn left in the y direction, and their phase durations are t ₁ , t ₂ , t ₃ and t ₄ respectively, then

t=t ₁ +t ₂ +t ₃ +t ₄

The average traffic flow of a single lane during each phase is n ₁ , n ₂ , n ₃ and n ₄ respectively, and the green light utilization rate η is defined as the ratio of the traffic flow of a single lane to the green light duration, then the green light duration of each green light phase The utilization rate is

The average utilization of the green light duration at the intersection is

In general, the above utilization ratios are not equal, that is,

This method dynamically adjusts the above t _i , (i=1,2,3,4) to make η _i , (i=1,2,3,4) and n _i , (i=1,2,3,4) ) to increase or decrease according to the same trend. Remember that at the end of a signal period, the measured traffic parameters during the signal period are t _i , (i=1,2,3,4) and Then the basic signal duration t _i ', (i=1,2,3,4) of each phase of the next signal cycle is

Obviously, the relationship between t _i ' and t _i satisfies

According to the actual situation of the intersection, each phase has a corresponding minimum green light time, which is recorded as t _gmin . According to the comparison result of t _i ' and t _gmin above, the setting of each signal duration in the next signal cycle is considered in two cases.

(1) t _i '3t _gmin ,(i=1,2,3,4)

At this time, t _i ' is taken as the signal duration of each phase in the next signal cycle. Obviously, the new signal cycle time remains unchanged, and the expected value of the green light utilization rate of each phase is the same, which is

(2) At least one phase j,j∈{1,2,3,4} exists, satisfying t' _j <t _gmin

At this time, the basic idea of determining the new timing length is to adjust the value of t _i ' smaller than t _gmin to t _gmin , and its "borrowed" time is evenly distributed to other phases. To this end, first sort t _i '(i=1,2,3,4) from small to large, record the new sequence as s _i , and make corresponding adjustments according to the relationship between s _i and t _gmin .

Combining the above (1) and (2), the overall flow of the signal timing algorithm corresponding to one signal cycle is shown in Figure 2.

4. Realization of signal timing automatic adjustment algorithm

The calculations involved in the signal timing automatic adjustment algorithm are mainly accumulation and division, and multiple timers are required; the time used to realize the algorithm is equivalent to one signal period of the signal light, generally about tens of seconds to one hundred seconds, very plenty. The automatic adjustment algorithm is implemented by the microprocessor. In addition, the display driver and I/O interface also need the microprocessor to manage (see Figure 1). Therefore, the microprocessor selection speed is not high, but the peripheral resources are abundant and the reliability is high. The product.

On-site implementation steps

After the traffic light controller is designed according to the above principles, its on-site installation is simple. It only needs to replace the new controller at the position where the traffic signal controller is installed on the roadside, connect the video surveillance signal at the intersection to the controller, and connect the output of the controller Signal to the signal lamp, set the initial parameters, and then start running, as shown in Figure 3.

The above content is only a basic description of the concept of the present invention, and any equivalent transformation made according to the technical solution of the present invention shall belong to the protection scope of the present invention.

Description of drawings

Figure 1 Frame structure diagram of intelligent traffic light control system

Figure 2 corresponds to a signal cycle automatic adjustment method for signal timing

Figure 3 On-site installation implementation flow chart

Figure 4 Comparison of Green Light Utilization Rates

Figure 5 Comparison of incoming vehicles and the number of vehicles waiting in line at each phase of the intersection

Example

According to the above method, the corresponding simulation is carried out on the computer. The simulation considers intersections with four signal phases, which are respectively marked as A, B, C and D. The incoming vehicles are randomly generated according to the Poisson distribution, and the simulation is carried out for 50 signal periods.

Figure 4 is a comparison of the total green light utilization rate at intersections, and the green light utilization rate corresponds to the formula (3) . It can be seen that after adopting this method, the green light utilization rate has been improved.

Figure 5 is a comparison of the number of incoming vehicles and vehicles waiting in line at each phase of the intersection. It can be seen from the figure that when this method is not adopted (i.e. the timing scheme), the queuing vehicles at intersections B and D continue to increase, forming congestion, while phase A and phase C have fewer incoming vehicles, and the green light passing time is not sufficient Utilize; After adopting this method, the queuing vehicle number of crossing B and crossing D has disappeared substantially, and crossing A and crossing C occasionally have vehicle to wait in line, but just disappears immediately. It can be seen that after adopting the method, the traffic condition at the intersection can be effectively and dynamically identified, the signal timing can be automatically adjusted, and the congestion can be reduced.

Cost and Benefit Estimation

(1) Cost

Taking an intersection as an example, the transformation investment needed to implement this method is only to replace the traffic light control machine, and at the same time transmit the video signal of the camera at the intersection to the traffic light control machine. The overall investment can be controlled within several thousand yuan.

(2) Benefits

Its benefits are mainly reflected in the reduction of fuel consumption (economic benefits), the reduction of exhaust emissions (environmental benefits), the improvement of travel efficiency and the improvement of traffic safety factors brought about by the corresponding reduction of drivers' bad psychological emotions (social benefits) when vehicles pass through the intersection. . Among them, it is difficult to give an accurate assessment of social benefits. Here, only a rough calculation is made for economic benefits and environmental benefits.

1. Economic benefits

The economic benefit comes from the saved vehicle fuel consumption, which is related to the traffic flow at the intersection. The traffic flow at the intersection is affected by factors such as road width and traffic time period, as shown in Table 1. The 12h traffic flow of the intersection can be obtained by adding the 12h traffic flow of the main road and the secondary road in the table. Considering that the traffic flow at night is much less than that during the day, the traffic flow at 12 hours at night is taken as 10% of the daytime. Therefore, the 24-hour traffic flow is obtained by multiplying the 12-hour traffic flow by a coefficient of 1.1, and the average 24-hour traffic flow can be further calculated The value is 16579, as shown in Table 2.

Table 1 Intersection Traffic Flow Standards

Table 2 24h Traffic Flow Standards at Intersections

After installing the intelligent traffic light controller, if the average waiting time of each vehicle at the intersection is reduced by 5 seconds, and the daily traffic flow at an intersection is calculated as 16,579 vehicles, the equivalent total time is 82,895 seconds. Taking the fuel consumption during the waiting period of the vehicle as 0.8 liters per hour, the fuel saved is about 18.4 liters per day, which is about 6716 liters per year. Based on the price of No. 93 gasoline of 7.94 yuan per liter (the price in Nantong in March 2013), it is equivalent to 53,325.04 yuan. From the perspective of direct economic benefits alone, it is enough to make up for the renovation cost of this intersection.

2. Environmental benefits

The carbon emission coefficient of gasoline is 2.361kgCO ₂ /L. According to the previous calculation results, the fuel saved at a crossing is about 6716 liters a year, and the reduced carbon emission is 3.361×6716=22.57 (tons). If extended to a Large cities, or the whole country, have huge numbers and significant environmental benefits.

references

[1] CCTV. Experts claim that traffic congestion in 15 Chinese cities loses 1 billion yuan per day [EB/OL]. http://news.xinhuanet.com/fortune/2012-08/23/c_123621201.htm, 2013-03- twenty three.

[2] Wen Zhida, Liang Guirong, Chen Biming, Gao Suping. Intelligent Traffic Light Control System Based on Traffic Flow [J]. Automation Technology and Application, 2009,28(6):115-118.

[3] Ma Hongwen, Chen Songli, Chen Zhiguo, Li Jian. A New Wireless Intelligent Dynamic Sensing Control System for Traffic Lights at Crossroads [J]. Microcomputer Applications, 2009, 30(4): 62-66.

[4] Zhang Wenpu. Road traffic detection [M]. Beijing: People's Communications Publishing House, 2010.

[5] Xu Jianmin. Traffic Management and Control [M]. Beijing: People's Communications Press, 2007.105-106.

[6] Jiangsu Environmental Monitoring Network [EB/OL].

Claims (4)

1. a kind of intelligent Control System for Traffic Lights, including monitoring camera (1), traffic lights and countdown lamp (2), its feature It is：The system also includes that intersection vehicle flux detection microprocessor (3), Traffic Signal Timing adjust automatically calculate microprocessor (4), driver module (5), Digital Image Processor (6), I/O interfaces (7)：

Monitoring camera (1) sends the video of acquisition to Digital Image Processor (6), and Digital Image Processor (6) carries out figure Result is exported to intersection vehicle flux detection microprocessor (3) after as processing, the intersection vehicle flux detects microprocessor (3) obtain information of vehicle flowrate and send Traffic Signal Timing adjust automatically to calculating microprocessor (4), the traffic through process Signal timing dial adjust automatically calculates microprocessor (4) after processing and obtaining signal timing dial result, calls I/O interfaces (7) and shows Show drive module (5), signal timing dial result is exported to traffic lights and countdown lamp (2)；

The Traffic Signal Timing adjust automatically calculates microprocessor (4) and adopts the signal timing dial for adjusting traffic lights with the following method：

A) both direction at note crossing is respectively x and y, if the signal period of traffic lights is t, containing four phase places, respectively x Direction straight trip, x directions are turned left, y directions are kept straight on, y directions are turned left, and its phase place duration is respectively t₁、t₂、t₃And t₄, then obtain formula (1)：

T=t₁+t₂+t₃+t₄(1)

B the magnitude of traffic flow number that single track averagely passes through during) setting each phase place is respectively n₁、n₂、n₃And n₄, define green light utilization rate η is the ratio of the magnitude of traffic flow that passes through of single track and long green light time, then the long green light time utilization rate of each green light phase place is respectively

$\left\{\begin{array}{c}{\mathrm{\&eta;}}_1=\frac{n_1}{t_1}\\ {\mathrm{\&eta;}}_2=\frac{n_2}{t_2}\\ {\mathrm{\&eta;}}_3=\frac{n_3}{t_3}\\ {\mathrm{\&eta;}}_4=\frac{n_4}{t_4}\end{array}\right.---\left(2\right)$

The long green light time average utilization at crossing is

$\stackrel{\&OverBar;}{\mathrm{\&eta;}}=\frac{\underset{i=1}{\overset{4}{\&Sigma;}}{n}_i}{\underset{i=1}{\overset{4}{\&Sigma;}}{t}_i}---\left(3\right)$

Generally, above-mentioned 5 utilization rates unequal, i.e.,

${\mathrm{\&eta;}}_1\&NotEqual;{\mathrm{\&eta;}}_2\&NotEqual;{\mathrm{\&eta;}}_3\&NotEqual;{\mathrm{\&eta;}}_4\&NotEqual;\stackrel{\&OverBar;}{\mathrm{\&eta;}}---\left(4\right)$

C, at the end of) remembering a signal period, during the signal period for measuring, traffic parameter is t_i, i=1,2,3,4 andThen The signal duration basic value t ' of next signal period each phase place_i, i=1,2,3,4 is

$\left\{\begin{array}{c}{t}_1^{\&prime;}=\frac{n_1}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}\\ t_2^{\&prime;}=\frac{n_2}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}\\ t_3^{\&prime;}=\frac{n_3}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}\\ t_4^{\&prime;}=\frac{n_4}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}\end{array}\right.---\left(5\right)$

t′_iAnd t_iBetween relation meet

${\mathrm{\&Sigma;t}}_i^{\&prime;}=\mathrm{\&Sigma;}\frac{n_i}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}=\frac{{\mathrm{\&Sigma;n}}_i}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}={\mathrm{\&Sigma;t}}_i---\left(6\right)$

D) according to the actual conditions at crossing, each phase place should mutually have a minimum green time, be designated as t_gmin, according to above-mentioned t '_iWith t_gminComparative result, the setting of each signal duration of next signal period considers in two kinds of situation：

(1)t′_i≥t_gmin, i=1,2,3,4

Take t '_iFor the signal duration of each phase place of next signal period, new signal period time-preserving, and each phase place is green Lamp utilization rate desired value is identical, is

(2) at least there is phase j, j ∈ { 1,2,3,4 } meet t'_j<t_gmin

Will be less than t_gminT '_iValue is adjusted to t_gmin, its time for borrowing equably shares other phase places, for this purpose, first by t ′_i, i=1,2,3,4 press ascending sequence, and new sequence is designated as s_i, according to s_iWith t_gminRelation, be adjusted correspondingly.

2. a kind of intelligent Control System for Traffic Lights as claimed in claim 1, it is characterised in that：

Intersection vehicle flux detection microprocessor (3) obtains information of vehicle flowrate using following steps：

A) identify in one signal period of traffic lights by the number of vehicles and vehicle of crossing all directions；

B) according to the length ratio of large car and compact car, equivalent kart number is converted into；

C the number is obtained the vehicle flowrate n in the per share track of the direction divided by the number of track-lines of the crossing direction)_i.

3. a kind of Intelligent traffic light control method, it is characterised in that：The method arranges a system,

The system includes that monitoring camera (1), traffic lights and countdown lamp (2), the system also include crossing wagon flow Amount detection microprocessor (3), Traffic Signal Timing adjust automatically calculate microprocessor (4), driver module (5), digitized map As processor (6), I/O interfaces (7)：

Monitoring camera (1) sends the video of acquisition to Digital Image Processor (6), and Digital Image Processor (6) carries out figure Result is exported to intersection vehicle flux detection microprocessor (3) after as processing, the intersection vehicle flux detects microprocessor (3) obtain information of vehicle flowrate and send Traffic Signal Timing adjust automatically to calculating microprocessor (4), the traffic through process Signal timing dial adjust automatically calculates microprocessor (4) after processing and obtaining signal timing dial result, calls I/O interfaces (7) and shows Show drive module (5), signal timing dial result is exported to traffic lights and countdown lamp (2)；

The Traffic Signal Timing adjust automatically calculates microprocessor (4) and adopts the signal timing dial for adjusting traffic lights with the following method：

A) both direction at note crossing is respectively x and y, if the signal period of traffic lights is t, containing four phase places, respectively x Direction straight trip, x directions are turned left, y directions are kept straight on, y directions are turned left, and its phase place duration is respectively t₁、t₂、t₃And t₄, then obtain formula (1)：

T=t₁+t₂+t₃+t₄(1)

B the magnitude of traffic flow number that single track averagely passes through during) setting each phase place is respectively n₁、n₂、n₃And n₄, define green light utilization rate η is the ratio of the magnitude of traffic flow that passes through of single track and long green light time, then the long green light time utilization rate of each green light phase place is respectively

$\left\{\begin{array}{c}{\mathrm{\&eta;}}_1=\frac{n_1}{t_1}\\ {\mathrm{\&eta;}}_2=\frac{n_2}{t_2}\\ {\mathrm{\&eta;}}_3=\frac{n_3}{t_3}\\ {\mathrm{\&eta;}}_4=\frac{n_4}{t_4}\end{array}\right.---\left(2\right)$

The long green light time average utilization at crossing is

$\stackrel{\&OverBar;}{\mathrm{\&eta;}}=\frac{\underset{i=1}{\overset{4}{\&Sigma;}}{n}_i}{\underset{i=1}{\overset{4}{\&Sigma;}}{t}_i}---\left(3\right)$

Generally, above-mentioned 5 utilization rates unequal, i.e.,

${\mathrm{\&eta;}}_1\&NotEqual;{\mathrm{\&eta;}}_2\&NotEqual;{\mathrm{\&eta;}}_3\&NotEqual;{\mathrm{\&eta;}}_4\&NotEqual;\stackrel{\&OverBar;}{\mathrm{\&eta;}}---\left(4\right)$

C, at the end of) remembering a signal period, during the signal period for measuring, traffic parameter is t_i, i=1,2,3,4 andThen The signal duration basic value t ' of next signal period each phase place_i, i=1,2,3,4 is

$\left\{\begin{array}{c}{t}_1^{\&prime;}=\frac{n_1}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}\\ t_2^{\&prime;}=\frac{n_2}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}\\ t_3^{\&prime;}=\frac{n_3}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}\\ t_4^{\&prime;}=\frac{n_4}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}\end{array}\right.---\left(5\right)$

t′_iAnd t_iBetween relation meet

${\mathrm{\&Sigma;t}}_i^{\&prime;}=\mathrm{\&Sigma;}\frac{n_i}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}=\frac{{\mathrm{\&Sigma;n}}_i}{\stackrel{\&OverBar;}{\mathrm{\&eta;}}}={\mathrm{\&Sigma;t}}_i---\left(6\right)$

D) according to the actual conditions at crossing, each phase place should mutually have a minimum green time, be designated as t_gmin, according to above-mentioned t '_iWith t_gminComparative result, the setting of each signal duration of next signal period considers in two kinds of situation：

(1)t′_i≥t_gmin, i=1,2,3,4

Take t '_iFor the signal duration of each phase place of next signal period, new signal period time-preserving, and each phase place is green Lamp utilization rate desired value is identical, is

(2) at least there is phase j, j ∈ { 1,2,3,4 } meet t'_j<t_gmin

Will be less than t_gminT '_iValue is adjusted to t_gmin, its time for borrowing equably shares other phase places, for this purpose, first by t ′_i, i=1,2,3,4 press ascending sequence, and new sequence is designated as s_i, according to s_iWith t_gminRelation, be adjusted correspondingly.

4. a kind of Intelligent traffic light control method as claimed in claim 3, it is characterised in that：

Intersection vehicle flux detection microprocessor (3) obtains information of vehicle flowrate using following steps：

A) identify in one signal period of traffic lights by the number of vehicles and vehicle of crossing all directions；

B) according to the length ratio of large car and compact car, equivalent kart number is converted into；

C the number is obtained the vehicle flowrate n in the per share track of the direction divided by the number of track-lines of the crossing direction)_i.