Traffic signal control system, method and equipment considering stability of average queuing length

Abstract

The invention discloses a traffic signal control system, method and device considering stability of average queuing length, and belongs to the technical field of intelligent traffic. The system comprises a vehicle-mounted unit, a roadside unit and a roadside signal machine, and the vehicle-mounted unit is connected with the roadside unit and used for collecting vehicle information and sending the vehicle information to the roadside unit; the roadside unit is connected with the roadside signal machine, analyzes the queue stability through a stability index calculation method based on a quadratic function based on vehicle information, and constructs a multi-objective optimization strategy of traffic signal control; and the roadside signal machine is used for receiving the multi-target optimization strategy to control the signal lamp. The signal lamp is controlled based on the multi-objective optimization strategy provided by the invention, and the traffic capacity of the intersection can be effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of intelligent transportation, more particularly to a traffic signal control system, method and device considering average queue length stability. BACKGROUND

[0002] With the rapid increase of urban vehicle quantity, urban traffic signal control is becoming increasingly complex. By reasonably controlling intersection traffic lights, adjusting traffic flow and improving intersection traffic efficiency, it becomes a crucial method to alleviate traffic congestion.

[0003] Traditional traffic signal control methods mostly focus on the optimization of a single target, such as maximizing the throughput and minimizing the delay, and less attention is paid to the stability control of the queue, and the dynamic changes of traffic flow and the comprehensive influence of vehicle queue length on traffic congestion and environmental pollution are not comprehensively considered. In actual traffic management, the stability of vehicle queue length is directly related to the alleviation degree of traffic congestion and the control effect of carbon dioxide emission. If the queue length is too long and unstable, it will not only lead to the decline of intersection traffic efficiency, but also cause the spread and intensification of traffic congestion, thereby increasing the idling time of vehicles and carbon dioxide emission.

[0004] Therefore, how to provide a traffic signal control system, method and device considering average queue length stability to solve the above problems is a problem that those skilled in the art need to solve. SUMMARY

[0005] Therefore, the present application provides a traffic signal control system, method and device considering average queue length stability to solve the above technical problems in the prior art.

[0006] In order to achieve the above purpose, the present application provides the following technical solutions: On the one hand, the present application provides a traffic signal control system considering average queue length stability, comprising: a vehicle-mounted unit, a roadside unit and a roadside signal machine. The vehicle-mounted unit is connected with the roadside unit, and is used for collecting vehicle information and sending the vehicle information to the roadside unit. The roadside unit is connected with the roadside signal machine, and analyzes the queue stability based on the vehicle information by using a stability index calculation method based on a quadratic function, and constructs a multi-objective optimization strategy for traffic signal control. The roadside signal machine is used for receiving the multi-objective optimization strategy to control the traffic lights.

[0007] On the other hand, the present application provides a traffic signal control method considering average queue length stability, which is applied to a traffic signal control system considering average queue length stability, and comprises the following steps: constructing a target strategy based on vehicle information; creating a queue model and calculating a queue growth amount; adding the queue growth amount to a target function to establish a multi-objective control model and constructing a multi-objective optimization strategy for traffic signal control; solving the multi-objective control model and controlling the signal light based on the multi-objective optimization strategy.

[0008] Preferably, the constructing a target strategy based on vehicle information comprises: establishing a target strategy Z1 aiming at minimizing carbon dioxide emissions and delay as follows: Z1=k1d+k2c; k1 and k2 represent coefficients of average delay time and average carbon dioxide emissions in the basic target strategy respectively, and the units are and ; d is the average delay time of the intersection (unit: s), and c is the average carbon dioxide emissions of the intersection (unit: g).

[0009] Preferably, the creating a queue model comprises: establishing a queue model as follows: ; updating the queue backlog at each time slice t according to the following formula: ; wherein, wherein, Q n ( t ) represents the traffic flow of intersection n at time t, the traffic flow as a kind of theoretical queuing is regarded as a queue in this context, and the inflow and outflow of the traffic flow correspond to the inflow and outflow of the queue; A n ( t ) represents the number of arriving vehicles of intersection n at time t, D n ( t ) represents the number of leaving vehicles of intersection n at time t , represents a correction term adjusted according to the priority, which adjusts the change of the queue length according to the priority of the vehicle, for the priority vehicle, is a positive value, and for the ordinary vehicle, is zero or a negative value.

[0010] More preferably, Pn(t) represents the total compensation flow adjusted according to the priority of the vehicle, which is a non-negative value: 0 vehicle for a single ordinary car, 0.5 vehicle for a single bus or taxi, and 1 vehicle for a single emergency vehicle (such as an ambulance, a fire truck, etc.).

[0011] Preferably, the calculation of the queue growth amount includes: The quadratic function is introduced, and the expression is: ; Wherein L ( t ) represents the queue length, which is a function that can reflect the queue backlog state, Q n ( t ) represents the traffic flow of intersection n at time t; The queue growth amount Δ(t) L(t+1)-L(t) is calculated, and the expression is: ; In the formula, wherein is a constant, is a variable, represents the maximum value of the arriving vehicles, represents the maximum value of the leaving vehicles, represents the maximum value of the priority vehicles.

[0012] Preferably, the queue growth amount is added to the target function to establish a multi-objective control model, including: Solving the minimum value of the queue growth amount and the first target Z1; Increasing the weight w to adjust the importance of the minimum value of the queue growth amount and the first target Z1 to obtain the second multi-objective optimization strategy Z2.

[0013] Preferably, the expression of the multi-objective optimization strategy Z2 is: Z2=C+w(k1d+k2c); In the formula, the variable , w is a non-negative weight, and the unit is , which adjusts the balance between C and the original target function, k1 and k2 respectively represent the coefficients of the average delay time and the average carbon dioxide emission in the basic target strategy, and the units are and ; d is the average delay time of the intersection (unit: s), and c is the average carbon dioxide emission of the intersection (unit: g).

[0014] In another aspect, the present application provides an electronic device, including a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to realize a traffic signal control method considering the stability of the average queue length.

[0015] Compared with the prior art, the traffic signal control system, method and equipment considering the average queue length stability provided by the technical solution disclosed in the present application can realize multi-objective optimization of traffic signal control by monitoring and analyzing vehicle queue length information in real time, combining with dynamic changes of traffic flow, and dynamically adjusting traffic signal control parameters. The method takes the average queue length as one of the important control indexes, analyzes the influence of different traffic signal control parameters on the original target strategy by constructing a queue model, and determines the optimal signal control scheme, thereby effectively improving the intersection passing capacity. The specific effects are as follows: (1) The priority of the vehicle is added to the queue model, a correction term for priority adjustment is added to the state equation, the change of the queue length is adjusted according to the priority of the vehicle, the form of the queue equation is changed, and the behavior of different vehicle priorities in the queue system is more accurately described.

[0016] (2) A quadratic function is introduced to calculate the queue growth, the value is controlled within a preset value range, and the value is added to the target strategy. By minimizing the growth and adjusting the importance of the two by means of the weight w, the queue stability is beneficially maintained. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0018] Figure 1 The control system schematic diagram of the present application; Figure 2 The control method flowchart of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described clearly and completely in the embodiments of the present application combined with the drawings. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0020] Referring to Figure 1 As shown in the figure, the present application discloses a traffic signal control system considering the average queue length stability, a vehicle-mounted unit, a roadside unit and a roadside signal machine. The vehicle-mounted unit is connected with the roadside unit and is used for collecting vehicle information and sending the vehicle information to the roadside unit. The roadside unit is connected with the roadside signal machine, and the queue stability is analyzed by a quadratic function-based stability index calculation method based on vehicle information (including real-time vehicle information and historical vehicle information), and a multi-objective optimization strategy of traffic signal control is constructed; The roadside signal machine is used for receiving the multi-objective optimization strategy to control the signal lamp.

[0021] Specifically, according to the module division, the system mainly includes two modules, which are a quadratic function-based stability index algorithm module and a multi-objective optimization strategy module, the quadratic function-based stability index algorithm module is mainly used for stability analysis of the queue, and the multi-objective optimization strategy module is used for forming a new multi-objective optimization strategy.

[0022] On the other hand, referring to Figure 2 The application discloses a traffic signal control method considering average queue length stability, applied to the traffic signal control system considering average queue length stability, and comprising the following steps: A target strategy is constructed based on vehicle information; A queue model is created, and a queue growth amount is calculated; The queue growth amount is added to a target function, a multi-objective control model is established, and a multi-objective optimization strategy of traffic signal control is constructed; A candidate phase of a traffic signal lamp of a to-be-controlled intersection is acquired, for each candidate phase, a comprehensive target function value of a corresponding lane is sequentially calculated, and a target value list of all candidate phases is obtained. Then, a phase with the minimum target value is selected from the list, and the signal lamp is switched to the phase, so that a queue-stable, delay-minimal and emission-optimal timing strategy is realized.

[0023] 1Specifically, the signal control method flow is as follows: first, a target strategy is constructed, then a queue model is created, a queue growth amount is calculated, vehicle ID and position information are acquired by a vehicle unit, the number of arriving and leaving vehicles and the size of traffic flow are obtained by comparing the vehicle ID at the current moment with the vehicle ID at the last moment, the queue growth amount is added to a target function, a multi-objective control model is established, a multi-objective optimization strategy of traffic signal control is constructed, a signal control algorithm is used to solve the multi-objective optimization strategy, the minimum value of the target strategy is calculated, and the corresponding lane is switched.

[0024] In one specific embodiment, the main content of the embodiment of the application mainly includes two parts: 1. The queue length is taken as a constraint condition of a target function, a queue with a quantity of n is defined for the constraint condition, a quadratic term function is introduced, the increment of the time t to t+1 is calculated, the queue is analyzed for stability, and a quadratic function-based stability index calculation method is formed. 2. Construct the objective function of traffic signal control optimization, aiming to minimize carbon dioxide emissions and delay, while adding the amount of queue growth, adjusting the importance of both by weight w, to form a new multi-objective optimization strategy.

[0025] In a specific embodiment, the following specific explanations are made for the above two parts: 1. Construct the objective strategy to minimize carbon dioxide emissions and delay, form the objective Z1 as follows: Z1=k1d+k2c; Where k1 and k2 represent the coefficients of the average delay time and the average carbon dioxide emissions in the basic objective strategy, respectively, with units of and ; d is the average delay time of the intersection (unit s), and c is the average carbon dioxide emissions of the intersection (unit g).

[0026] Specifically, first construct a Z1, then add the amount of queue growth, to form a new multi-objective optimization strategy.

[0027] More specifically, the carbon dioxide emissions can be obtained according to the automobile exhaust detector.

[0028] 2. Establish a queue model as At each time slice t, update the queue backlog according to the following formula: ; Where, Q n ( t ) represents the traffic flow of intersection n at time t, which is a theoretical queue in this context, and the inflow and outflow of traffic correspond to the inflow and outflow of the queue; A n ( t ) represents the number of arriving vehicles at intersection n at time t , D n ( t ) represents the number of vehicles leaving intersection n at time t , and Pn(t) represents the total compensation flow according to vehicle priority adjustment, which is a non-negative value: a single ordinary car is not compensated for 0 vehicles, a single bus or taxi is compensated for 0.5 vehicles, and a single emergency vehicle (such as an ambulance, fire truck, etc.) is compensated for 1 vehicle.

[0029] Specifically, create a queue model according to the vehicle ID and location information For example, by comparing the vehicle IDs at the current time with those at the previous time, one can obtain the number of arriving and departing vehicles, as well as the traffic volume.

[0030] 3. Stability index calculation method based on quadratic functions: Introducing the quadratic function, its expression is: ; Where L(t) is a function that reflects the queue backlog state. Q n (t) This represents the traffic flow at intersection n at time t; Calculate the growth rate of the queue Δ(t): ; The specific calculation process is as follows: ; In the formula, there is an upper limit to the growth of the queue. .in, It is a constant. It is a variable. This indicates the maximum number of arriving vehicles. This represents the maximum value of vehicles leaving the area. This represents the maximum value of the total compensation flow adjusted according to priority. Since it is a constant, we only need to minimize This will make the system more stable.

[0031] Specifically, the above method calculates the queue growth based on a quadratic function, and then calculates a stability index, which is to ensure that the queue growth is less than or equal to B+C.

[0032] Specifically, the calculation results show that the queue growth is less than or equal to the sum of a constant and a variable, that is... To keep the queue stable and prevent it from growing indefinitely, the result on the right side of the inequality should be expressed as the sum of a constant and a variable. Since the constant will not change, the queue can be kept stable simply by minimizing the variable.

[0033] 4. Incorporate the queue growth rate into the objective function, simultaneously solve for the minimum value of both the queue growth rate and Z1, and use weights w to adjust the degree of emphasis on both, forming a new multi-objective optimization strategy Z2. Minimize the value of Z2: Z2 = C + w(k1d + k2c); In the formula, variables w represents the non-negative weight, in units of Adjusting the balance between C and the original objective function, k1 and k2 represent the coefficients of average delay time and average carbon dioxide emissions in the basic objective strategy, respectively, with units of... and d represents the average delay time of the intersection (in seconds), and c represents the average carbon dioxide emissions of the intersection (in grams).

[0034] On the other hand, embodiments of the present invention also disclose an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a traffic signal control method that takes into account the stability of the average queue length.

[0035] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0036] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A traffic signal control system considering the stability of average queue length, characterized in that, include: Onboard unit, roadside unit, roadside signal controller; The vehicle-mounted unit is connected to the roadside unit and is used to collect vehicle information and send it to the roadside unit; The roadside unit is connected to the roadside signal controller. Based on vehicle information, the stability of the queue is analyzed by a stability index calculation method based on quadratic functions, and a multi-objective optimization strategy for traffic signal control is constructed. The roadside traffic signal controller is used to receive multi-objective optimization strategies to control the traffic lights.

2. A traffic signal control method considering the stability of average queue length, applied to the traffic signal control system considering the stability of average queue length as described in claim 1, characterized in that, include: Constructing target strategies based on vehicle information; Create a queue model and calculate the queue growth rate; By incorporating queue growth into the objective function, a multi-objective control model is established, and a multi-objective optimization strategy for traffic signal control is constructed. A multi-objective control model is solved, and traffic lights are controlled based on a multi-objective optimization strategy.

3. A traffic signal control method considering the stability of average queue length according to claim 2, characterized in that, The target construction strategy based on vehicle information includes: With the goal of minimizing carbon dioxide emissions and delays, the target strategy Z1 is established as follows: Z1 = k1d + k2c; Where k1 and k2 represent the weighting coefficients of delay time and carbon dioxide emissions in the objective function, d is the average delay of the intersection, and c is the average carbon dioxide emissions of the intersection.

4. A traffic signal control method considering the stability of average queue length according to claim 2, characterized in that, The creation of the queue model includes: Establish a queue model for ; At each time slice t, the queue backlog is updated according to the following formula: ； in, Q n ( t () represents the traffic flow at intersection n at time t. A n ( t () represents the number of vehicles arriving at intersection n at time t. D n ( t ) represents the time n of intersection n. t The number of vehicles that left. This indicates a priority-based adjustment, which adjusts the queue length according to the vehicle's priority. For priority vehicles, It is a positive value for ordinary vehicles. It is zero or a negative value.

5. A traffic signal control method considering the stability of average queue length according to claim 2, characterized in that, The calculation of queue growth includes: Introducing the quadratic function, its expression is: ； in L ( t () indicates the queue length. Q n ( t () represents the traffic flow at intersection n at time t; Calculate the growth rate Δ(t) of the queue. The expression for L(t+1)-L(t) is: ； In the formula, where, It is a constant. It is a variable. This indicates the maximum number of arriving vehicles. This represents the maximum value of vehicles leaving the area. This indicates the maximum value for priority vehicles.

6. A traffic signal control method considering the stability of average queue length according to claim 2, characterized in that, By incorporating the queue growth rate into the objective function, a multi-objective control model is established, including: Find the minimum value of queue growth and the first objective Z1; By increasing the weight w and adjusting the emphasis on the queue growth rate and the minimum value of the first objective Z1, a second multi-objective optimization strategy Z2 is obtained.

7. A traffic signal control method considering the stability of average queue length according to claim 6, characterized in that, The expression for the multi-objective optimization strategy Z2 is: Z2 = C + w(k1d + k2c); In the formula, variables w is the weight, k1 and k2 represent the weighting coefficients of delay time and carbon dioxide emissions in the objective function, d is the average delay of the intersection, and c is the average carbon dioxide emissions of the intersection.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements a traffic signal control method that takes into account the stability of average queue length as described in any one of claims 2 to 7.

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