Maximum pressure traffic signal coordination control method of variable signal period

Abstract

The invention discloses a maximum pressure traffic signal coordination control method of a variable signal period, and relates to the technical field of traffic management control. According to the variable period maximum voltage signal control method, green time distribution is calculated according to the single-phase operation maximum voltage, signal phase sequence orderliness is considered, the duration is dynamically distributed according to the real-time traffic flow, the duration of the new period changes along with the real-time traffic flow, reasonable timing is provided for signal coordination control, and the control efficiency is improved. Phase green light duration calculation is designed, the difference value between the vehicle density and the downstream density of the road section in the previous second is taken as a pressure value, statistics is not carried out during the green light period, and the extra green light duration is distributed for the non-counted vehicles possibly generating extra passing demands during the period according to the maximum pressure control theory.

Description

Technical Field

[0001] This invention relates to the field of traffic management and control technology, specifically to a method for coordinated control of maximum pressure traffic signals with variable signal cycles. Background Technology

[0002] In recent years, with the rapid pace of urbanization, traffic congestion has become an increasingly prominent problem and a common challenge in urban development. Dynamically optimizing signal timing through advanced adaptive signal control has become an important means of alleviating congestion at urban intersections.

[0003] Maximum pressure traffic signal control is an advanced distributed signal control method that effectively prevents queue overflow, ensures vehicles can move efficiently and smoothly through the network, and maximizes network throughput.

[0004] However, traditional maximum pressure signal control methods can only achieve isolated real-time response at a single intersection, and cannot coordinate the work of multiple intersections on a main line. At the same time, traditional main line signal coordination control cannot update the signal timing scheme in real time to meet the traffic demand of the intersection.

[0005] Therefore, a new solution is needed to address the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a maximum pressure traffic signal coordination control method with variable signal period to solve the technical problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a maximum pressure traffic signal coordination control method with variable signal period, comprising the following steps:

[0008] S1: Select the maximum pressure parameter to meet the dynamic coordination requirements;

[0009] S2: Based on the traditional maximum pressure signal control method, a variable period maximum pressure signal control strategy with adaptive signal coordination control is established. The variable period maximum pressure control strategy is used to dynamically adjust the period and green light duration according to the real-time pressure value while fixing the phase sequence.

[0010] S3: Based on the additional traffic demand at the signalized intersection, establish a variable cycle maximum pressure phase green time optimization strategy. The phase green time optimization strategy dynamically adjusts the green light duration of the coordinated phase by calculating the additional traffic demand.

[0011] S4: Combine the variable period maximum pressure timing scheme to establish the phase difference of the maximum pressure dynamic coordination control model based on the variable period;

[0012] S5: Based on the phase difference, establish a variable period dynamic maximum pressure transition period model.

[0013] Further, S1 includes the following steps:

[0014] To meet the requirements of dynamic coordination, the selection of pressure parameters will not be limited to queue length, but will instead use the traffic flow density of the road segment as the pressure parameter for maximum pressure.

[0015] Let l represent the set of approach lanes, and m represent the set of corresponding exit lanes. The density... The pressure value of the phase is calculated as a pressure parameter, and the selected phase pressure parameter is defined as follows:

[0016]

[0017] In the formula: This indicates the pressure values ​​at the inlet channel l and the outlet channel m. This indicates the number of vehicles in lane l; Indicates the maximum number of vehicles allowed on lane l; x m x represents the number of vehicles in lane m; mmax This represents the maximum number of vehicles allowed on lane m.

[0018] Based on the pressure values ​​mentioned above, the pressure value of a phase can be derived. The pressure of phase j at intersection i is defined as the sum of the absolute pressures of all corresponding traffic flows at j, expressed as: .

[0019] Further, S2 includes the following steps:

[0020] First, determine the calculation method for the maximum pressure of the variable period;

[0021] Based on a standard four-phase signalized intersection, This represents the green light duration for the j-th phase of the i-th cycle at the intersection. Now, if we want to find... The magnitude of the signal is then set to be in phase with the three preceding signals. , , To form a complete signal cycle, calculate the green ratio;

[0022] Similarly, the calculation yields... , , and the magnitude of the subsequent phase;

[0023] Based on the above method for calculating the maximum pressure of the variable period, the formula for calculating the current phase green light ratio is derived:

[0024]

[0025]

[0026] In the formula, P ij Indicates an intersection i In calculating phase j The sum of the pressures of the current phase and the three phases preceding it; p ij Indicates an intersection i middle j The pressure value of the phase; This represents the green light ratio of phase j;

[0027] The virtual period and green light ratio of the phase determined by the above method can be used to deduce the green light duration allocated to the current phase that needs to be released:

[0028]

[0029]

[0030] In the formula, This indicates the duration of the green light for phase j; This indicates the duration of the imaginary period formed by phase j and its three preceding phases.

[0031] Further, S3 includes the following steps:

[0032] The additional phase extension time within a single cycle is defined as the time required for vehicles to dissipate within a single cycle when additional traffic demand occurs.

[0033] Coordination direction:

[0034]

[0035] In the formula, This represents the phase extension time required to coordinate the phase during the k-th signal cycle of the i-th intersection. This represents the coordinated phase extension green time pressure at the i-th intersection during the k-th signal cycle; This represents the sum of the imaginary periodic pressure formed by phase k (during the fixed green time period) and its three preceding phases; This indicates the duration of the imaginary period formed by phase k and its three preceding phases;

[0036] Calculate the average phase delay time for the first n repetition cycles with additional traffic demand within the coordinated phase at the i-th intersection. This serves as the extension time for the current phase adjustment:

[0037]

[0038] In the formula, This represents the actual delay time of the coordinated phase within the k-th signal period of the i-th intersection; n represents the number of iteration optimization periods ( ); This represents the weighting coefficients for the previous n cycles of the current phase;

[0039] For each coordinating phase, the actual extension value of the coordinating phase is calculated once according to the above formula. And require: This is used to determine whether the actual extension value is within the adjustment threshold;

[0040] In the trunk line system, the calculation approach is to calculate the green light duration of a phase before coordinating phase release, and there is a certain phase difference between each intersection.

[0041] To ensure that the selection of critical intersections in the trunk system is completed within the same signal cycle, and to guarantee the rationality of the determination of critical intersections, constraints are set between relative phase difference and extension value:

[0042]

[0043] In the formula, This represents the duration of the red light at intersection i during cycle k. This represents the relative phase difference between intersection i and intersection j within period k; This represents the initial maximum pressure allocation green time duration for the k-th cycle coordinated phase at intersection i;

[0044] The coordinated random green time value for non-critical intersections is defined as follows:

[0045] The coordinated random green time pressure value is the pressure difference during the coordinated phase random green time period at each intersection in the same cycle:

[0046]

[0047]

[0048] In the formula, This represents the coordinated phase extension green time pressure at the i-th intersection during the k-th signal cycle; This indicates the pressure difference between critical and non-critical intersections;

[0049] Combining the above pressure values, the coordinated random green time value for non-critical intersections can be calculated as follows:

[0050] In the formula, This indicates that phase i (during the fixed green time period) and its three preceding phases constitute the sum of the imaginary periodic pressure.

[0051] Further, S4 includes the following steps:

[0052] First, a multi-objective coordinated optimization method is adopted to establish a dynamic coordinated control model based on the maximum pressure with a variable period, i.e., a multi-objective control objective function:

[0053]

[0054] In the formula, This represents the distance from the i-th intersection to the j-th downstream intersection; This represents the pressure difference between the i-th intersection and the downstream intersection; This indicates the average speed of the vehicle. This represents the average delay time at the i-th intersection; This represents the queue length at the i-th intersection; This represents the saturation level of the i-th intersection; This represents the corresponding weight coefficient for the target.

[0055] Then, the constraints are established as follows:

[0056] 1) Maximum green light duration constraint :

[0057]

[0058]

[0059] In the formula, C is the signal period duration; p i G represents the phase pressure value of the i-th phase. i，min and G i，max These are the minimum and maximum green light times for that phase, respectively.

[0060] 2) Phase difference constraint:

[0061]

[0062] Indicates the minimum phase difference; Indicates the maximum phase difference; This represents the relative phase difference of intersection j during period k;

[0063] 3) Signal period constraint:

[0064]

[0065] In the formula, C i (k) represents the duration of the signal cycle at the i-th intersection during the k-th signal cycle; C min and C max These are the minimum and maximum period durations of the phase, respectively;

[0066] 4) Clear time constraints:

[0067] To ensure that vehicles do not conflict during phase transitions, the clearing time for each phase is (yellow light time plus all-red light time). It should meet the following requirements:

[0068]

[0069] In the formula, This indicates the vehicle clearance time for phase j at intersection i; This indicates the yellow light duration for phase j at the i-th intersection; This indicates the red light time for phase j at the i-th intersection; This represents the minimum time required to clear vehicles from phase j at intersection i.

[0070] 5) Queue length constraint:

[0071] To prevent queue overflow, the queue length Q at each intersection is set at a certain value. i The queue length must be limited to the maximum length that the intersection can accommodate:

[0072]

[0073] In the formula, This represents the maximum queue length at intersection i.

[0074] 6) Delay time constraint:

[0075]

[0076] In the formula, This represents the maximum acceptable delay time for the i-th intersection;

[0077] 7) Saturation flow constraint:

[0078]

[0079] This represents the actual flow rate v for each phase. ij The saturation flow rate S not exceeding that phase ij .

[0080] Further, S5 includes the following steps:

[0081] Set a constraint on the phase difference, including maximum and minimum thresholds:

[0082]

[0083] Build a transition cycle model:

[0084] Using the first intersection passed in the direction of traffic as the standard, when resetting the signal cycle, the cycle with the longest cycle length among the first n cycles that satisfy the phase difference constraint for green wave passage at that intersection is used. As a transition period for standard intersections;

[0085] Assuming the phase difference at period k does not meet the constraints, a transition period adjustment is needed for this period. The phase difference can be determined before the start of traffic release in the last phase of period k-1, and the transition period duration of the standard intersection can also be determined at this time. Therefore, the start time of the standard intersection in signal period k+1, where the optimal phase difference is implemented, can be obtained, denoted as […]. ;

[0086] Meanwhile, the optimal phase difference for period k+1 also needs to be given before the end of period k-1. However, solving for the optimal phase difference requires prior knowledge of the signal timing scheme for period k+1, which is crucial for understanding the pressure on each phase of period k+1 at intersection i. Cycle duration Defined as:

[0087]

[0088]

[0089] At this point, the timing scheme for each phase of cycle k+1 is calculated using the average pressure value and average cycle duration. Then, the optimal phase difference is calculated using an optimization model, thus determining the start time of cycle k+1 for each intersection. Given the start time of period k ,but:

[0090]

[0091] After obtaining the period of each intersection, the timing scheme of each phase in the transition period k can be obtained by calculating the maximum pressure.

[0092] Compared with the prior art, the beneficial effects of the present invention are:

[0093] 1. The variable cycle maximum pressure signal control method proposed in this invention calculates the green time allocation based on the maximum pressure of single-phase operation, takes into account the orderly nature of the signal phase sequence, dynamically allocates the duration according to the real-time traffic flow, and the new cycle duration changes with the real-time traffic flow, providing reasonable timing for signal coordination control.

[0094] 2. The present invention designs the phase green light duration calculation based on the difference between the vehicle density of the road segment and the downstream density one second before the release as the pressure value. The green light period is not counted. For vehicles that may generate additional traffic demand during the period but are not counted, the additional green light duration is allocated according to the maximum pressure control theory.

[0095] 3. This invention designs a variable period maximum pressure signal coordinated control model to prioritize the calculation of the coordinated phase green time, and combines it with the optimal phase difference model to calculate the optimal phase difference between upstream and downstream of the trunk line. The intersection is released according to the phase difference. For the change of relative phase difference, a transition period theory is proposed. When the critical value is exceeded, the phase difference is reset to maintain the green wave bandwidth and efficiency. Attached Figure Description

[0096] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0097] Figure 1 This is a schematic diagram of the method flow of the present invention;

[0098] Figure 2 This is a graph showing the variation of average queue length under different traffic flow demands according to the present invention;

[0099] Figure 3 This is a comparison chart of the average queue length changes of five control methods at 3500 pcu / h according to the present invention;

[0100] Figure 4 This is a comparison chart of the average delay of the five control methods of this invention;

[0101] Figure 5 This invention provides a comparison of the velocity changes between DVC-MP and Fix-C.

[0102] Figure 6 This is a comparison chart of the velocity changes of DVC-MP and OC-MP in this invention;

[0103] Figure 7 This is a comparison chart of the speed changes of DVC-MP and SCOOT according to the present invention;

[0104] Figure 8 This is a comparison chart of the changes in average vehicle delay under the influence of the variable periodic phase difference of the present invention;

[0105] Figure 9 The average queue length of vehicles under the influence of the variable periodic phase difference of this invention. Detailed Implementation

[0106] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0107] This invention uses road segment vehicle density as a pressure parameter, considers the real-time pressure difference changes of each phase, and integrates the signal coordination control theory of trunk traffic network systems to propose a variable period dynamic maximum pressure signal coordination control method based on fixed phase sequence.

[0108] First, the traditional maximum pressure is modified by considering a fixed phase sequence. The traditional maximum pressure control scheme that calculates the signal timing throughout the entire cycle is updated to calculate the pressure difference and signal timing in separate phases.

[0109] Then, by calculating the proportion of additional traffic demand generated by randomly arriving vehicles during the green light period of the release phase in the phase pressure value, the additional green light duration is reasonably allocated to meet the traffic demand of the remaining queue.

[0110] Secondly, an optimal phase difference model for signal coordination control is constructed. Based on the green light duration of the coordinated phase, the optimal phase difference between upstream and downstream in the coordination system is calculated to achieve coordination optimization of the trunk system.

[0111] This invention can realize the integration of pressure-driven local optimization and collaborative control strategies, and can simultaneously meet the dual requirements of dynamic regulation of intersections and overall performance optimization of arterial roads.

[0112] The following specific examples are presented:

[0113] Please see Figure 1 A method for coordinated control of maximum pressure traffic signals with variable signal cycles includes the following steps:

[0114] S1: Select the maximum pressure parameter to meet the dynamic coordination requirements;

[0115] S2: Based on the traditional maximum pressure signal control method, a variable period maximum pressure signal control strategy with adaptive signal coordination control is established. The variable period maximum pressure control strategy is used to dynamically adjust the period and green light duration according to the real-time pressure value while fixing the phase sequence.

[0116] S3: Based on the additional traffic demand at the signalized intersection, establish a variable cycle maximum pressure phase green time optimization strategy. The phase green time optimization strategy dynamically adjusts the green light duration of the coordinated phase by calculating the additional traffic demand.

[0117] S4: Combine the variable period maximum pressure timing scheme to establish the phase difference of the maximum pressure dynamic coordination control model based on the variable period;

[0118] S5: Based on the phase difference, establish a variable period dynamic maximum pressure transition period model.

[0119] S1 includes the following steps:

[0120] To meet the requirements of dynamic coordination, the selection of pressure parameters will not be limited to queue length, but will instead use the traffic flow density of the road segment as the pressure parameter for maximum pressure.

[0121] Let l represent the set of approach lanes, and m represent the set of corresponding exit lanes. The density... The pressure value of the phase is calculated as a pressure parameter, and the selected phase pressure parameter is defined as follows:

[0122]

[0123] In the formula: This indicates the pressure values ​​at the inlet channel l and the outlet channel m. This indicates the number of vehicles in lane l; Indicates the maximum number of vehicles allowed on lane l; x m x represents the number of vehicles in lane m; mmax This represents the maximum number of vehicles allowed on lane m.

[0124] Based on the pressure values ​​mentioned above, the pressure value of a phase can be derived. The pressure of phase j at intersection i is defined as the sum of the absolute pressures of all corresponding traffic flows at j, expressed as: .

[0125] S2 includes the following steps:

[0126] Traditional maximum pressure signal control methods suffer from frequent maximum pressure phase calculations and frequent, disordered phase switching. To apply maximum pressure to signal coordination control methods, it is necessary to ensure that the phase sequence of intersection signals is fixed. Therefore, a variable period maximum pressure control strategy is proposed.

[0127] First, determine the calculation method for the maximum pressure of the variable period;

[0128] Based on a standard four-phase signalized intersection, This represents the green light duration for the j-th phase of the i-th cycle at the intersection. Now, if we want to find... The magnitude of is then set to be in phase with the three signals preceding it, i.e. , , To form a complete signal cycle, i.e., imaginary period 1, the green ratio can be calculated.

[0129] Similarly, it can be calculated that , , and the magnitude of the subsequent phase;

[0130] Based on the above method for calculating the maximum pressure of the variable period, the formula for calculating the current phase green light ratio is derived:

[0131]

[0132]

[0133] In the formula, P ij Indicates an intersection i In calculating phase j The sum of the pressures of the current phase and the three phases preceding it; p ij Indicates an intersection i middle j The pressure value of the phase; This represents the green light ratio of phase j;

[0134] The green light duration allocated to the current phase, determined by the virtual period and the green light ratio of that phase, can be derived from the above method:

[0135]

[0136]

[0137] In the formula, This indicates the duration of the green light for phase j; This indicates the duration of the imaginary period formed by phase j and its three preceding phases.

[0138] S3 includes the following steps:

[0139] The additional phase extension time within a single cycle is defined as the time required for vehicles to dissipate within a single cycle when additional traffic demand occurs.

[0140] Coordination direction:

[0141]

[0142] In the formula, This represents the phase extension time required to coordinate the phase during the k-th signal cycle of the i-th intersection. This represents the coordinated phase extension green time pressure at the i-th intersection during the k-th signal cycle; This represents the sum of the imaginary periodic pressure formed by phase k (during the fixed green time period) and its three preceding phases; This indicates the duration of the imaginary period formed by phase k and its three preceding phases;

[0143] Calculate the average phase delay time for the first n repetition cycles with additional traffic demand within the coordinated phase at the i-th intersection. This serves as the extension time for the current phase adjustment:

[0144]

[0145] In the formula, This represents the actual delay time of the coordinated phase within the k-th signal period of the i-th intersection; n represents the number of iteration optimization periods ( ); This represents the weighting coefficients for the previous n cycles of the current phase;

[0146] For each coordinating phase, the actual extension value of the coordinating phase is calculated once according to the above formula. And require: This is used to determine whether the actual extension value is within the adjustment threshold;

[0147] In the trunk line system, the calculation approach is to calculate the green light duration of a phase before coordinating phase release, and there is a certain phase difference between each intersection.

[0148] To ensure that the selection of critical intersections in the trunk system is completed within the same signal cycle, and to guarantee the rationality of the determination of critical intersections, constraints are set between relative phase difference and extension value:

[0149]

[0150] In the formula, This represents the duration of the red light at intersection i during cycle k. This represents the relative phase difference between intersection i and intersection j within period k; This represents the initial maximum pressure allocation green time duration for the k-th cycle coordinated phase at intersection i;

[0151] The coordinated random green time value for non-critical intersections is defined as follows:

[0152] The coordinated random green time pressure value is the pressure difference during the coordinated phase random green time period at each intersection in the same cycle:

[0153]

[0154]

[0155] In the formula, This represents the coordinated phase extension green time pressure at the i-th intersection during the k-th signal cycle; This indicates the pressure difference between critical and non-critical intersections.

[0156] Combining the pressure values ​​mentioned above, the coordinated random green time value for non-critical intersections can be calculated as follows: .

[0157] In the formula, This indicates that phase i (during the fixed green time period) and its three preceding phases constitute the sum of the imaginary periodic pressure.

[0158] S4 includes the following steps:

[0159] To maximize throughput at intersections in the trunk line system while further reducing overall delays, a variable-cycle maximum pressure coordinated control phase difference optimization model is established to solve for the optimal phase difference between each intersection, thereby achieving dynamic adaptive control of the coordinated phase and deriving the optimal coordinated control scheme.

[0160] First, a multi-objective coordinated optimization method is adopted to establish a dynamic coordinated control model based on the maximum pressure with a variable period, i.e., a multi-objective control objective function:

[0161]

[0162] In the formula, This represents the distance from the i-th intersection to the j-th downstream intersection; This represents the pressure difference between the i-th intersection and the downstream intersection; This indicates the average speed of the vehicle. This represents the average delay time at the i-th intersection; This represents the queue length at the i-th intersection; This represents the saturation level of the i-th intersection; This represents the corresponding weight coefficient for the target.

[0163] Then, the constraints are set as follows:

[0164] 1) Maximum green light duration constraint:

[0165] The green light time for each phase must be within a reasonable range to ensure sufficient traffic capacity and safety.

[0166]

[0167]

[0168] In the formula, C is the signal period duration; p i G represents the phase pressure value of the i-th phase. i，min and G i，max These represent the minimum and maximum green light times for that phase, respectively.

[0169] 2) Phase difference constraint:

[0170] The phase difference must be within a certain range, which can be expressed as:

[0171]

[0172] 3) Signal period constraint:

[0173]

[0174] In the formula, C i (k) represents the duration of the signal cycle at the i-th intersection during the k-th signal cycle; C min and C max These are the minimum and maximum period durations of that phase, respectively.

[0175] 4) Clear time constraints:

[0176] To ensure that vehicles do not conflict during phase transitions, the clearing time for each phase is (yellow light time plus all-red light time). It should meet the following requirements:

[0177]

[0178] In the formula, This indicates the vehicle clearance time for phase j at intersection i. This indicates the yellow light duration for phase j at the i-th intersection; This indicates the red light time for phase j at the i-th intersection; This represents the minimum time required to clear vehicles from phase j at intersection i.

[0179] 5) Queue length constraint:

[0180] To prevent queue overflow, the queue length Q at each intersection is set at a certain value. i The queue length must be limited to the maximum length that the intersection can accommodate:

[0181]

[0182] In the formula, This represents the maximum queue length at intersection i.

[0183] 6) Delay time constraints:

[0184] Delay time D i Traffic congestion should be kept within a reasonable range to reduce vehicle delays.

[0185]

[0186] In the formula, This represents the maximum acceptable delay time for intersection i.

[0187] 7) Saturation flow constraint:

[0188]

[0189] The actual flow rate v of each phase ij The saturation flow rate S of this phase should not be exceeded. ij .

[0190] S5 includes the following steps:

[0191] The varying lengths of signal cycles introduce new problems: the phase difference calculated before coordination begins, and the timing scheme for control at each intersection initially based on the corresponding phase difference, will increase or decrease as the traffic is allowed to pass over multiple cycles due to the different cycles between intersections. This will inevitably affect the green wave bandwidth, thus reducing the coordination effect. To address this, a solution is proposed to avoid this situation by setting a constraint on the phase difference, including maximum and minimum thresholds:

[0192]

[0193] In the formula, Indicates the minimum phase difference; Indicates the maximum phase difference; This represents the relative phase difference of intersection j during period k;

[0194] Build a transition cycle model:

[0195] Using the first intersection passed in the direction of traffic as the standard, when resetting the signal cycle, the cycle with the longest cycle length among the first n cycles that satisfy the phase difference constraint for green wave passage at that intersection is used. As a transition period for standard intersections;

[0196] Assuming the phase difference at period k does not meet the constraints, a transition period adjustment is needed for this period. The phase difference can be determined before the start of traffic release in the last phase of period k-1. The transition period duration of the standard intersection can also be determined at this time. Therefore, the start time of the standard intersection in signal period k+1, where the optimal phase difference is implemented, can be obtained, denoted as […]. ;

[0197] Meanwhile, the optimal phase difference for period k+1 also needs to be given before the end of period k-1. However, solving for the optimal phase difference requires prior knowledge of the signal timing scheme for period k+1. Combining the methods discussed earlier, the pressure on each phase of period k+1 at intersection i is... Cycle duration Defined as:

[0198]

[0199]

[0200] At this point, the timing scheme for each phase of cycle k+1 is calculated using the average pressure value and average cycle duration. Then, the optimal phase difference is calculated using an optimization model. This allows us to determine the start time of cycle k+1 at each intersection. Given the start time of period k ,but:

[0201]

[0202] After obtaining the period of each intersection, the timing scheme of each phase in the transition period k can be obtained by calculating the maximum pressure.

[0203] It should be noted that although the timing scheme for the k+1 period is given before the end of the k-1 period, this timing scheme is only used to calculate the optimal phase difference duration. The signal timing scheme for the k+1 period is still calculated using the aforementioned maximum voltage of the variable period.

[0204] Based on the above embodiments:

[0205] A trunk line simulation environment can be built using SUMO to compare and analyze various signal coordination control methods.

[0206] The experiment uses three intersections as examples. A simulated road network was constructed, traffic flow was set, and vehicle turning ratios were configured based on the road network. For vehicles on arterial roads, the ratios for left turns, straight ahead, and right turns were set to 20%, 60%, and 20%, respectively; for vehicles on non-arterial roads, the ratios were set to 40%, 40%, and 20%, respectively. The signal control method used at each intersection was a standard symmetrical four-phase release. In the simulation test, a total of five different control methods were tested: Dynamic Coordinated Control of Variable Period Maximum Pressure Signals (DVC-MP), Original Maximum Pressure Coordinated Control Considering Common Period (OC-MP), Fixed Signal Timing Coordinated Control (Fix-C), Adaptive Coordinated Control of Signals (SCOOT), and Variable Period Maximum Pressure Signal Control (V-MP) for comparative analysis.

[0207] Figures 2-9 The results show that, under five different traffic flow scenarios (2500-4500 pcu / h), the variable period maximum pressure signal dynamic coordination control method has certain advantages for the signal optimization of trunk line coordination. Compared with SCOOT, OC-MP and Fix-C, it has significant control effects under various traffic flow demands, reducing the average queue length by 23.5% and the average vehicle delay by 16.2%.

[0208] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for coordinated control of maximum pressure traffic signals with variable signal cycles, characterized in that: Includes the following steps: S1: Select the maximum pressure parameter to meet the dynamic coordination requirements; S2: Based on the traditional maximum pressure signal control method, a variable period maximum pressure signal control strategy with adaptive signal coordination control is established. The variable period maximum pressure control strategy is used to dynamically adjust the period and green light duration according to the real-time pressure value while fixing the phase sequence. S3: Based on the additional traffic demand at the signalized intersection, establish a variable cycle maximum pressure phase green time optimization strategy. The phase green time optimization strategy dynamically adjusts the green light duration of the coordinated phase by calculating the additional traffic demand. S4: Combine the variable period maximum pressure timing scheme to establish the phase difference of the maximum pressure dynamic coordination control model based on the variable period; S5: Based on the phase difference, establish a variable period dynamic maximum pressure transition period model.

2. The maximum pressure traffic signal coordination control method with variable signal period according to claim 1, characterized in that: S1 includes the following steps: To meet the requirements of dynamic coordination, the traffic flow density of the road segment will be selected as the pressure parameter for maximum pressure. Let l represent the set of approach lanes, and m represent the set of corresponding exit lanes. The density... The pressure value of the phase is calculated as a pressure parameter, and the selected phase pressure parameter is defined as follows: ； In the formula: This indicates the pressure values ​​at the inlet channel l and the outlet channel m. This indicates the number of vehicles in lane l; Indicates the maximum number of vehicles allowed on lane l; x m x represents the number of vehicles in lane m; mmax This represents the maximum number of vehicles allowed on lane m. Based on the pressure values ​​mentioned above, the pressure value of a phase can be derived. The pressure of phase j at intersection i is defined as the sum of the absolute pressures of all corresponding traffic flows at j, expressed as: .

3. The maximum pressure traffic signal coordination control method with variable signal period according to claim 2, characterized in that: S2 includes the following steps: First, determine the calculation method for the maximum pressure of the variable period; Based on a standard four-phase signalized intersection, This represents the green light duration for the j-th phase of the i-th cycle at the intersection. Now, if we want to find... The magnitude of the signal is then set to be in phase with the three preceding signals. , , To form a complete signal cycle, calculate the green ratio; Similarly, the calculation yields... , , and the magnitude of the subsequent phase; Based on the above method for calculating the maximum pressure of the variable period, the formula for calculating the current phase green light ratio is derived: ； ； In the formula, P ij Indicates an intersection i In calculating phase j The sum of the pressures of the current phase and the three phases preceding it; p ij Indicates an intersection i middle j The pressure value of the phase; This represents the green light ratio of phase j; The virtual period and green light ratio of the phase determined by the above method can be used to deduce the green light duration allocated to the current phase that needs to be released: ； ； In the formula, This indicates the duration of the green light for phase j; This indicates the duration of the imaginary period formed by phase j and its three preceding phases.

4. The maximum pressure traffic signal coordination control method with variable signal period according to claim 3, characterized in that: S3 includes the following steps: The additional phase extension time within a single cycle is defined as the time required for vehicles to dissipate within a single cycle when additional traffic demand occurs. Coordination direction: ； In the formula, This represents the phase extension time required to coordinate the phase during the k-th signal cycle of the i-th intersection. This represents the coordinated phase extension green time pressure at the i-th intersection during the k-th signal cycle; This represents the sum of the imaginary periodic pressure formed by phase k (during the fixed green time period) and its three preceding phases; This indicates the duration of the imaginary period formed by phase k and its three preceding phases; Calculate the average phase delay time for the first n repetition cycles with additional traffic demand within the coordinated phase at the i-th intersection. This serves as the extension time for the current phase adjustment: ； In the formula, This represents the actual delay time of the coordinated phase within the k-th signal period of the i-th intersection; n represents the number of iteration optimization periods ( ); This represents the weighting coefficients for the previous n cycles of the current phase; For each coordinating phase, the actual extension value of the coordinating phase is calculated once according to the above formula. And require: This is used to determine whether the actual extension value is within the adjustment threshold; In the trunk line system, the calculation approach is to calculate the green light duration of a phase before coordinating phase release, and there is a certain phase difference between each intersection. To ensure that the selection of critical intersections in the trunk system is completed within the same signal cycle, and to guarantee the rationality of the determination of critical intersections, constraints are set between relative phase difference and extension value: ； In the formula, This represents the duration of the red light at intersection i during cycle k. This represents the relative phase difference between intersection i and intersection j within period k; This represents the initial maximum pressure allocation green time duration for the k-th cycle coordinated phase at intersection i; The coordinated random green time value for non-critical intersections is defined as follows: The coordinated random green time pressure value is the pressure difference during the coordinated phase random green time of each intersection in the same cycle: ； ； In the formula, This represents the coordinated phase extension green time pressure at the i-th intersection during the k-th signal cycle; This indicates the pressure difference between critical and non-critical intersections; Combining the above pressure values, the coordinated random green time value for non-critical intersections can be calculated as follows: ; In the formula, This indicates that phase i (during the fixed green time period) and its three preceding phases constitute the sum of the imaginary periodic pressure.

5. The maximum pressure traffic signal coordination control method with variable signal period according to claim 4, characterized in that: S4 includes the following steps: First, a multi-objective coordinated optimization method is adopted to establish a dynamic coordinated control model based on the maximum pressure with a variable period, i.e., a multi-objective control objective function: ； In the formula, This represents the distance from the i-th intersection to the j-th downstream intersection; This represents the pressure difference between the i-th intersection and the downstream intersection; This indicates the average speed of the vehicle. This represents the average delay time at the i-th intersection; This represents the queue length at the i-th intersection; This represents the saturation level of the i-th intersection; This represents the corresponding weight coefficient for the target. Then, the constraints are established as follows: 1) Maximum green light duration constraint : ； ； In the formula, C is the signal period duration; p i G represents the phase pressure value of the i-th phase. i，min and G i，max These are the minimum and maximum green light times for that phase, respectively. 2) Phase difference constraint: ； Indicates the minimum phase difference; Indicates the maximum phase difference; This represents the relative phase difference of intersection j during period k; 3) Signal period constraint: ； In the formula, C i (k) represents the duration of the signal cycle at the i-th intersection during the k-th signal cycle; C min and C max These are the minimum and maximum period durations of the phase, respectively; 4) Clear time constraints: To ensure that vehicles do not conflict during phase transitions, the clearing time for each phase is (yellow light time plus all-red light time). Should meet: ； In the formula, This indicates the vehicle clearance time for phase j at intersection i; This indicates the yellow light duration for phase j at the i-th intersection; This indicates the red light time for phase j at the i-th intersection; This represents the minimum time required to clear vehicles from phase j at intersection i. 5) Queue length constraint: To prevent queue overflow, the queue length Q at each intersection is set at a certain value. i The queue length must be limited to the maximum length that the intersection can accommodate: ； In the formula, This represents the maximum queue length at intersection i. 6) Delay time constraint: ； In the formula, This represents the maximum acceptable delay time for the i-th intersection; 7) Saturation flow constraint: ； This represents the actual flow rate v for each phase. ij The saturation flow rate S not exceeding that phase ij .

6. The maximum pressure traffic signal coordination control method with variable signal period according to claim 5, characterized in that: S5 includes the following steps: Set a constraint on the phase difference, including maximum and minimum thresholds: ； Build a transition cycle model: Using the first intersection passed in the direction of traffic as the standard, when resetting the signal cycle, the cycle with the longest cycle length among the first n cycles that satisfy the phase difference constraint for green wave passage at that intersection is used. As a transition period for standard intersections; Assuming the phase difference at period k does not meet the constraints, a transition period adjustment is needed for this period. The phase difference can be determined before the start of traffic release in the last phase of period k-1, and the transition period duration of the standard intersection can also be determined at this time. Therefore, the start time of the standard intersection in signal period k+1, where the optimal phase difference is implemented, can be obtained, denoted as […]. ; Meanwhile, the optimal phase difference for period k+1 also needs to be given before the end of period k-1. However, solving for the optimal phase difference requires prior knowledge of the signal timing scheme for period k+1, which is crucial for understanding the pressure on each phase of period k+1 at intersection i. Cycle duration Defined as: ； ； At this point, the timing scheme for each phase of cycle k+1 is calculated using the average pressure value and average cycle duration. Then, the optimal phase difference is calculated using an optimization model, thus determining the start time of cycle k+1 for each intersection. Given the start time of period k ,but: ； After obtaining the period of each intersection, the timing scheme of each phase in the transition period k can be obtained by calculating the maximum pressure.

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