Multi-phase traffic signal timing method

Abstract

The invention discloses a multiphase traffic signal timing method, and relates to the technical field of intelligent traffic, and the method comprises the steps: obtaining the input parameters of multiphase traffic signal timing; wherein the input parameters comprise the cooperation period, the traffic flow, the minimum value of the distance to the previous intersection, the maximum value of the traffic flow difference value and the minimum value of the traffic flow difference value; calculating the green time ratio of each phase based on the difference value of the bidirectional traffic flow of each phase and the difference value of the minimum value of the distance from the previous intersection in the bidirectional direction; based on the green time ratio of each phase, establishing a plurality of phase ratios through equal division of each ratio; and according to the total cooperation period, the green light duration of each phase is solved. According to the method, the difference value of the phase bidirectional traffic flow and the difference value of the minimum value of the distance from the previous intersection in two directions serve as input through every two phases, the green time ratio is calculated through the fuzzy algorithm, multiple phase ratios are established through equal division of all the ratios, the green light duration of all the phases is calculated according to the total cooperation period, and therefore more reasonable and accurate signal timing is achieved.

Description

Technical Field

[0001] The invention relates to the field of intelligent traffic technology, and in particular to a multi-phase traffic signal timing method. Background Art

[0002] Traffic lights are an important tool for urban traffic management. Their main purpose is to improve road capacity, reduce traffic congestion and ensure traffic safety by reasonably allocating the time and space of traffic flow. Among them, the three-phase signal timing method is a common traffic signal control method, which is mainly used to solve the traffic flow control problem at multi-lane intersections. The core of this method is to divide the signal timing of the intersection into three phases according to the characteristics of traffic flow and traffic organization, so as to achieve smooth, efficient and safe operation of traffic flow.

[0003] At present, most of the three-phase intersection signal timing methods use the Webster formula for timing, which mainly determines the signal cycle of each phase based on traffic flow. The Webster formula assumes that all traffic flows arrive and leave on the critical lane of the road, but in fact vehicles may enter or leave the intersection from non-critical lanes.

[0004] Therefore, this method may not accurately calculate the traffic flow on non-critical lanes. At the same time, the Webster formula is a method of calculating signal timing with the goal of minimizing vehicle delay time, and its cycle length is based on the calculation of vehicle delay. Therefore, if the setting of signal timing leads to other unconsidered factors such as environmental pollution, noise, etc., this method cannot be effectively handled. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a multi-phase traffic signal timing method, which takes the difference between the two-way traffic flow of each phase and the difference between the minimum distance of the two-way distance to the previous intersection as input, calculates the green-to-signal ratio using a fuzzy algorithm, and then establishes multiple phase ratios by dividing each ratio equally, and then calculates the green light duration of each phase based on the total coordination cycle, thereby achieving more reasonable and accurate signal timing.

[0006] To this end, the present invention adopts the following technical solutions:

[0007] The present invention provides a multi-phase traffic signal timing method, the method comprising:

[0008] Obtaining input parameters for multi-phase traffic signal timing; wherein the input parameters include: coordination period, vehicle flow, minimum distance to the previous intersection, maximum vehicle flow difference, and minimum vehicle flow difference;

[0009] Based on the difference in two-way traffic volume in each phase and the difference in the minimum two-way distance to the previous intersection, the green-signal ratio of each phase is calculated;

[0010] Based on the green-to-signal ratio of each phase, multiple phase ratios are established by dividing each ratio equally; according to the total coordination cycle, the green light duration of each phase is calculated.

[0011] Furthermore, based on the green-to-signal ratio of each phase, multiple phase ratios are established by dividing each ratio equally; according to the total coordination cycle, the green light duration of each phase is calculated, including:

[0012] Assume that the two-phase cycle is t, the yellow light time is Ty, the full red time is Tr, the three-phase green light time ratio is T'1:T'2:T'3, and the three-phase green light time is T1g, T2g, T3g;

[0013] The green signal ratio of the first phase to the second phase is s1:s2;

[0014] T1g=(s1*t) / (s1+s2)-Ty;

[0015] T2g = (s2*t) / (s1+s2)-Ty-Tr;

[0016] The green signal ratio of the second phase to the third phase is t1:t2;

[0017] T'2g = (t1*t) / (t1+t2)-Ty;

[0018] T3g = (t2*t) / (t1+t2)-Ty-Tr;

[0019] According to the green signal ratio between the first phase and the second phase, and the green signal ratio between the second phase and the third phase, the green light duration ratios of the three phases are established;

[0020] According to T2g / T'2g=a / b, where a and b are constants, we can obtain T'1:T'2:T'3;

[0021] The cycle of the intersection is T, and the total green light duration is T-3*Ty-3*Tr;

[0022] Based on the obtained T'1:T'2:T'3, the three-phase timing scheme is obtained:

[0023] T1=(T-3*Ty-3*Tr)*T'1 / (T'1+T'2+T'3);

[0024] T2=(T-3*Ty-3*Tr)*T'2 / (T'1+T'2+T'3);

[0025] T3=(T-3*Ty-3*Tr)*T'3 / (T'1+T'2+T'3).

[0026] Furthermore, the green-to-signal ratio of each phase is calculated, including:

[0027] A fuzzy control model is constructed and the green-to-signal ratio of each phase is calculated using the fuzzy control model; the fuzzy control model uses the difference between the two-way traffic flow of each phase and the difference between the minimum two-way distance to the previous intersection as input parameters.

[0028] Furthermore, a fuzzy control model is constructed, including:

[0029] Create the difference ef of the traffic flow between east-west and south-north, the difference ed of the minimum distance between east-west and south-north from the previous intersection, and the fuzzy domain of green-signal ratio u;

[0030] By using scale transformation, the difference input of the east-west and south-north two-way traffic flow and the difference input of the minimum distance from the previous intersection between the east-west and south-north two-way are transformed into the required fuzzy domain range;

[0031] A triangle is used as the difference between the east-west and south-north bidirectional traffic flow, the difference between the minimum distance from the east-west and south-north bidirectional to the previous intersection, and the green-to-signal ratio fuzzy set membership function;

[0032] Based on expert knowledge and control objectives, a fuzzy rule table is formulated;

[0033] Using the maximum-minimum method, the relationship matrix of each rule is obtained according to the fuzzy rule table. and

[0034]

[0035] By R A and R B The green-to-signal ratio output is:

[0036] The weighted average method is used to calculate the green-to-signal ratio of the fuzzy quantity;

[0037] After obtaining the clear value u0, the u0 scale is transformed into the actual control value.

[0038] Furthermore, the fuzzy rule table is:

[0039]

[0040] Among them, NMef, NSef, ZOef, PSef, and PMef represent the negative middle, small negative, zero, small positive, and positive middle of the difference in traffic volume ef between the east-west and south-north directions respectively; NMed, NSed, ZOed, PSed, and PMed represent the negative middle, small negative, zero, small positive, and positive middle of the difference in the minimum distance from the east-west and south-north directions to the previous intersection ed respectively; NMu, NSu, ZOu, PSu, and PMu represent the negative middle, small negative, zero, small positive, and positive middle of the green signal ratio u respectively.

[0041] The multi-phase traffic signal timing method proposed in the present invention calculates the green-to-signal ratio by considering the difference in two-way traffic flow and the minimum distance to the previous intersection, and uses a fuzzy algorithm to allocate the green light duration of each phase, which has the following beneficial effects:

[0042] 1. More accurate signal timing: By comparing two directions, taking into account the difference in two-way traffic volume and the distance between intersections, it can more accurately reflect the actual traffic demand in each direction, thereby achieving more reasonable signal timing.

[0043] 2. Improve the capacity of the road network: Accurate green-to-signal ratio calculation can balance the traffic flow in each phase, reduce congestion, and improve the capacity and efficiency of the entire road network.

[0044] 3. Reduce vehicle delays: Optimized signal timing can reduce vehicle waiting time, reduce travel delays, and provide a smoother driving experience.

[0045] 4. Improve traffic safety: Reasonable allocation of green light duration can reduce the risk of traffic accidents caused by unreasonable signal timing and improve road traffic safety.

[0046] In addition, the timing scheme of the present invention can shorten the waiting time of vehicles at intersections, reduce the idling of vehicles, help reduce fuel consumption and exhaust emissions, and reduce environmental pollution. The timing scheme of the present invention can also reduce the number of vehicle stops, effectively reduce traffic noise, and improve the living environment of residents.

[0047] In general, the multi-phase traffic signal timing method of the present invention can provide a more intelligent and refined signal control strategy, which has a significant positive impact on improving the overall performance of the urban traffic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0049] Figure 1 It is a flow chart of a multi-phase traffic signal timing method in an embodiment of the present invention;

[0050] Figure 2 The flowchart of calculating the green-to-signal ratio by using the fuzzy control model in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0053] like Figure 1 As shown, a multi-phase traffic signal timing method in an embodiment of the present invention specifically includes the following steps:

[0054] S1. Obtaining input parameters for multi-phase traffic signal timing;

[0055] The input parameters include: coordination period, traffic volume, minimum distance to the previous intersection, maximum traffic volume difference, and minimum traffic volume difference. The specific descriptions of these parameters are as follows:

[0056] Coordination cycle: refers to the duration of a complete cycle of a traffic light, usually including the sum of the green, yellow and red light times of all phases. The determination of the coordination cycle needs to take into account the overall traffic conditions of the intersection to ensure that traffic flows in all directions can get reasonable service time.

[0057] Traffic flow: refers to the number of vehicles passing through a specific road section within a certain period of time. Traffic flow is a very important parameter in signal timing, which directly reflects the traffic demand of the road.

[0058] Minimum distance to the previous intersection: This usually refers to the shortest distance between the current intersection and the upstream adjacent intersection in the case of multiple consecutive intersections. This parameter is crucial for determining the travel time of vehicles between two intersections and setting appropriate signal timing.

[0059] Maximum traffic flow difference: It may refer to the maximum difference in traffic flow in different directions during the observation period. This parameter helps to understand the maximum deviation of traffic demand in different directions during the coordination period, so as to make a more reasonable green-signal ratio allocation.

[0060] Minimum traffic flow difference: Corresponding to the maximum value, it represents the minimum difference in traffic flow in different directions during the observation period. Knowing the minimum deviation helps to ensure that sufficient green time is provided for each direction even when traffic demand is close to uniform.

[0061] These parameters work together in the signal timing model to ensure that signal control can adapt to changes in different traffic conditions and improve the efficiency and safety of intersections. Through the accurate measurement and rational use of these parameters, more refined control of traffic lights can be achieved, thereby optimizing traffic flow, reducing delays and waiting time, reducing environmental pollution, and improving the efficiency of the overall transportation system.

[0062] S2, based on the difference of two-way traffic flow in each phase and the difference of the minimum distance from the previous intersection in both directions, calculate the green-signal ratio of each phase;

[0063] The green-light ratio refers to the proportion of time available for vehicle traffic in a traffic light cycle, that is, the ratio of the effective green light time of a phase to the cycle length. Preferably, the green-light ratio can be calculated using a fuzzy control model. The green-light ratio of two phases specifically refers to: the ratio of the green-light ratio of one phase to the green-light ratio of two phases, and the ratio of the green-light ratio of two phases to the green-light ratio of three phases.

[0064] S3. Based on the green-to-light ratio of each phase, multiple phase ratios are established by dividing each ratio equally (the green-to-light ratio of the first phase to the second phase is s1:s2 and the green-to-light ratio of the second phase to the third phase is t1:t2); based on the total coordination cycle, the green light duration of each phase is calculated.

[0065] In a specific implementation, it is assumed that the two-phase cycle is t, the yellow light time is Ty, the full red time is Tr, the three-phase green light time ratio is T'1:T'2:T'3, and the three-phase green light time is T1g, T2g, and T3g.

[0066] (1) The green signal ratio of the first phase to the second phase is s1:s2;

[0067] T1g=(s1*t) / (s1+s2)-Ty;

[0068] T2g = (s2*t) / (s1+s2)-Ty-Tr;

[0069] (2) The green signal ratio of the second phase to the third phase is t1:t2;

[0070] T'2g = (t1*t) / (t1+t2)-Ty;

[0071] T3g = (t2*t) / (t1+t2)-Ty-Tr;

[0072] (3) Establish the green light duration ratios of the three phases based on (1) and (2);

[0073] According to T2g / T'2g=a / b, where a and b are constants, T'1:T'2:T'3 can be obtained.

[0074] (4) The cycle of the intersection is T, and the total green light duration is T-3*Ty-3*Tr.

[0075] (5) According to (3), we get:

[0076] T1=(T-3*Ty-3*Tr)*T'1 / (T'1+T'2+T'3);

[0077] T2=(T-3*Ty-3*Tr)*T'2 / (T'1+T'2+T'3);

[0078] T3=(T-3*Ty-3*Tr)*T'3 / (T'1+T'2+T'3);

[0079] This gives a three-phase timing scheme {T1, T2, T3}.

[0080] Calculation example:

[0081] Assume that the green signal ratio between the first phase and the second phase is s1:s2=2:3; the green signal ratio between the second phase and the third phase is t1:t2=3:2, Ty=3, t=60, Tr=3, T=80

[0082] (1)T1g=(s1*t) / (s1+s2)-Ty=21;

[0083] T2g=(s2*t) / (s1+s2)-Ty-Tr=30;

[0084] (2)T'2g=(t1*t) / (t1+t2)-Ty=33;

[0085] T3g=(t2*t) / (t1+t2)-Ty-Tr=18;

[0086] (3) According to T2g / T'2g=10 / 11, we obtain T'1:T'2:T'3=77:110:60.

[0087] (4) The cycle of the intersection is T, and the total green light duration is T-3*Ty-3*Tr=62.

[0088] (5) According to (3), we get:

[0089] T1=(T-3*Ty-3*Tr)*T'1 / (T'1+T'2+T'3)=19;

[0090] T2=(T-3*Ty-3*Tr)*T'2 / (T'1+T'2+T'3)=28;

[0091] T3=(T-3*Ty-3*Tr)*T'3 / (T'1+T'2+T'3)=15.

[0092] For ease of understanding, the preferred implementation of calculating the green-to-signal ratio using the fuzzy control model is described in detail below. Calculating the green-to-signal ratio using the fuzzy control model specifically includes the following steps:

[0093] S2-1. Create the difference ef of the east-west and south-north bidirectional traffic flow, the difference ed of the minimum distance from the previous intersection between the east-west and south-north bidirectional traffic flow, and the fuzzy domain of the green-signal ratio u.

[0094] (1) Set the difference ef between east-west and south-north bidirectional traffic flow to {-3, -2, -1, 0, 1, 2, 3};

[0095] The difference ed between the minimum distances from the previous intersection in the east-west and north-south directions is {-3, -2, -1, 0, 1, 2, 3};

[0096] The green-to-signal ratio u is {-3, -2, -1, 0, 1, 2, 3}.

[0097] (2) Setting fuzzy subsets

[0098] The fuzzy subset of the difference ef between the east-west and south-north bidirectional traffic flow is {NMef, NSef, ZOef, PSef, PMef};

[0099] The fuzzy subset of the difference ed of the minimum distance between the east-west and north-south bidirectional distances from the previous intersection is {NMed, NSed, ZOed, PSed, PMed};

[0100] The fuzzy subset of green signal ratio u is {NMu, NSu, ZOu, PSu, PMu}.

[0101] S2-2. Use scale transformation to transform the input quantity into the required fuzzy domain range.

[0102] Actual input of the difference in traffic volume between east-west and south-north The actual range of variation is The fuzzy domain is [-3, 3], then:

[0103]

[0104] The actual input value of the difference between the minimum distance from the previous intersection in both directions between east and west and north and south The actual range of variation is The fuzzy domain is [-3, 3], then:

[0105]

[0106] S2-3. The fuzzy set membership function is chosen to be a triangle.

[0107] The membership function of the difference between east-west and south-north bidirectional traffic flow ef is as follows: Figure 2 And as shown in Table 1.

[0108] Table 1

[0109]

[0110] The membership function of the difference ed between the minimum distances from the previous intersection in both directions of east-west and north-south is shown in Table 2.

[0111] Table 2

[0112]

[0113] The membership function of green letter ratio u is shown in Table 3.

[0114] Table 3

[0115]

[0116] S2-4, define the fuzzy rule table;

[0117] In fuzzy control systems, fuzzy rules are a series of rules used to describe the relationship between input variables and output variables. These rules are usually based on human natural language and empirical knowledge, and are expressed using structures such as "if-then". Terms in fuzzy rules NM, NS, ZO, PS, and PM in fuzzy rules stand for Negative Middle, Negative Small, Zero, Positive Small, and Positive Middle, respectively. These terms are used to describe the degree of membership of elements in a fuzzy set and are the vocabulary used in fuzzy control to describe the state of input and output variables. Specifically:

[0118] NM (Negative Middle): Indicates that a value is in the middle range of the negative area, that is, it tends to be negative but is not particularly large.

[0119] NS (Negative Small): Indicates that a value is in the negative area and the value is small.

[0120] ZO (Zero): Indicates that a value is close to zero or in a neutral state between positive and negative.

[0121] PS (Positive Small): Indicates that a value is in the positive area and the value is small.

[0122] PM (Positive Middle): Indicates that a value is in the middle range of the positive area, that is, it tends to be positive but is not particularly large.

[0123] These terms are used to express the degree of membership, that is, the degree to which a value belongs to a fuzzy set.

[0124] In this embodiment, a series of fuzzy rules are formulated based on expert knowledge and control objectives, as shown in Table 4.

[0125] Table 4

[0126]

[0127] S2-5. Use fuzzy reasoning to obtain the fuzzy relationship matrix.

[0128] In this embodiment, fuzzy reasoning adopts the maximum-minimum method, and the relationship matrix R of each rule is obtained according to the fuzzy rule table. Ai , R Bi Get the fuzzy relationship matrix and in:

[0129]

[0130] By RA and R B The green-to-signal ratio output can be obtained as: Represents a composition operator.

[0131] S2-6, defuzzification, using weighted average method to clarify the fuzzy quantity:

[0132]

[0133] Among them, x i is the domain value, μ i (x i ) is the domain value x i Membership value.

[0134] S2-7, transform the domain of green-to-signal ratio to obtain the green-to-signal ratio;

[0135] After obtaining the clarity value u0, it needs to be scaled to the actual control value. The transformation range of u0 is [-3, 3], and the transformation range of the actual green-to-signal ratio is [u min ,u max ],but:

[0136]

[0137] in, Called quantization factor, umax=1, umin=0.

[0138] The above steps use fuzzy algorithm to obtain the green-to-signal ratio.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-phase traffic signal timing method, characterized in that: The method comprises: Obtaining input parameters for multi-phase traffic signal timing; wherein the input parameters include: coordination period, vehicle flow, minimum distance to the previous intersection, maximum vehicle flow difference, and minimum vehicle flow difference; Based on the difference in two-way traffic volume in each phase and the difference in the minimum two-way distance to the previous intersection, the green-signal ratio of each phase is calculated; Based on the green-to-signal ratio of each phase, multiple phase ratios are established by dividing each ratio equally; according to the total coordination cycle, the green light duration of each phase is calculated.

2. A multi-phase traffic signal timing method according to claim 1, characterized in that: Based on the green-to-signal ratio of each phase, multiple phase ratios are established by dividing each ratio equally; According to the total coordination cycle, the green light duration of each phase is calculated, including: Assume that the two-phase cycle is t, the yellow light time is Ty, the full red time is Tr, the three-phase green light time ratio is T1:T2:T3, and the three-phase green light time is T1g, T2g, T3g; The green signal ratio of the first phase to the second phase is s1:s2; T1g=(s1*t) / (s1+s2)-Ty; T2g = (s2*t) / (s1+s2)-Ty-Tr; The green signal ratio of the second phase to the third phase is t1:t2; T'2g = (t1*t) / (t1+t2)-Ty; T3g = (t2*t) / (t1+t2)-Ty-Tr; According to the green signal ratio between the first phase and the second phase, and the green signal ratio between the second phase and the third phase, the green light duration ratios of the three phases are established; According to T2g / T'2g=a / b, where a and b are constants, we can obtain T'1:T'2:T'3; The cycle of the intersection is T, and the total green light duration is T-3*Ty-3*Tr; Based on the obtained T'1:T'2:T'3, the three-phase timing scheme is obtained: T1=(T-3*Ty-3*Tr)*T'1 / (T'1+T'2+T'3); T2=(T-3*Ty-3*Tr)*T'2 / (T'1+T'2+T'3); T3=(T-3*Ty-3*Tr)*T'3 / (T'1+T'2+T'3).

3. A multi-phase traffic signal timing method according to claim 1, characterized in that: Calculate the green-to-signal ratio of each phase, including: A fuzzy control model is constructed, and the green-to-signal ratio of each phase is calculated using the fuzzy control model; the fuzzy control model uses the difference between the two-way traffic flow of each phase and the difference between the minimum two-way distance to the previous intersection as input parameters.

4. A multi-phase traffic signal timing method according to claim 3, characterized in that: Construct a fuzzy control model, including: Create the difference ef of the east-west and south-north bidirectional traffic flow, the difference ed of the minimum distance from the previous intersection between the east-west and south-north bidirectional traffic flow, and the fuzzy domain of the green-signal ratio u; By using scale transformation, the difference input of the east-west and south-north bidirectional traffic flow and the difference input of the minimum distance from the previous intersection between the east-west and south-north bidirectional traffic flow are transformed into the required fuzzy domain range; A triangle is used as the difference between the east-west and south-north bidirectional traffic flow, the difference between the minimum distance from the east-west and south-north bidirectional to the previous intersection, and the green-to-signal ratio fuzzy set membership function; Based on expert knowledge and control objectives, a fuzzy rule table is formulated; Using the maximum-minimum method, the relationship matrix of each rule is obtained according to the fuzzy rule table. and By R A and R B The green-to-signal ratio output is: The weighted average method is used to calculate the green-to-signal ratio of the fuzzy quantity; After obtaining the clear value u0, the u0 scale is transformed into the actual control value.

5. A multi-phase traffic signal timing method according to claim 4, characterized in that: The fuzzy rule table is: Among them, NMef, NSef, ZOef, PSef, and PMef represent the negative middle, small negative, zero, small positive, and positive middle of the difference in traffic volume ef between the east-west and south-north directions respectively; NMed, NSed, ZOed, PSed, and PMed represent the negative middle, small negative, zero, small positive, and positive middle of the difference in the minimum distance from the east-west and south-north directions to the previous intersection ed respectively; NMu, NSu, ZOu, PSu, and PMu represent the negative middle, small negative, zero, small positive, and positive middle of the green signal ratio u respectively.

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