Construction method of dynamic traffic model of signal trunk road

Abstract

The invention provides a method for constructing a dynamic traffic model of a signal trunk road. The method comprises the following steps: S1, constructing a simplified microscopic model of vehicle movement; s2, according to the ordered movement of the traffic flow queue along the main road, marking the signal period of each intersection along the way by using an incremental sequence, the same mark of the signal period reflecting the time-space association of the vehicle fleet of the adjacent road section; s3, the dynamic traffic demand of each intersection is indexed by using the mark of the signal period, and the traffic flow from the upstream main road and the upstream side road is emphasized and distinguished; and S4, for each intersection, defining the traffic retention volume of the previous signal period as a traffic state, and constructing a traffic dynamic equation. According to the method, the switching signal moment is directly used as a decision variable, the problem that other models do not directly simulate the influence of signal change on traffic conditions is effectively solved, and the method is suitable for main road real-time signal cooperative control; with the road section and the signal period as units, the model scale is minimum; model input can be directly measured, and calculation is simple.

Description

Technical Field

[0001] The present invention belongs to the field of traffic signal control, and in particular relates to a method for constructing a dynamic traffic model of a signal trunk road. Background Art

[0002] The increasing pressure on urban arterial roads caused by the increasing traffic demand is becoming increasingly prominent. Traffic flow models can help analyze traffic operation patterns and changing patterns, which is helpful for traffic signal control and traffic system management. On signalized arterial roads, when traffic signals switch, the dynamic response of traffic is sudden. From the perspective of computer science or control engineering, signal changes mark the asynchronous occurrence of events. Along the timeline, changes in traffic patterns and the occurrence of these events drive the dynamics of the traffic system. Arterial road signal control needs to consider the coordinated relationship between signals at multiple intersections along the route, requiring the corresponding dynamic traffic model to describe the interaction between orderly signal changes and traffic flow responses.

[0003] Traffic flow models are primarily categorized into micro, meso, and macro models. Micro models focus on the dynamics of individual vehicles, such as the cellular automaton model, which discretizes roads into grids to simulate vehicle movement. However, these models have too many state variables, resulting in complex calculations and, for arterial roads, they fail to abstract the dynamic traffic patterns used to determine signal switching. Macro models describe traffic flow as a fluid, such as the store-and-forward strategy used to address congestion. This strategy abstracts signal switching by averaging traffic flow during the green light period on a path, averaging traffic flow over the entire signal cycle, and generating a set of traffic dynamic equations containing only continuous variables. These models provide a steady-state model for the system but do not include the instantaneous variables that determine signal switching, thus failing to meet the aforementioned requirements. Summary of the Invention

[0004] The present invention mainly aims to provide a method for constructing a dynamic traffic model of a signalized trunk road in response to the above-mentioned problems.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for constructing a dynamic traffic model for a signalized trunk road comprises the following steps:

[0007] S1. Construct a simplified microscopic model of vehicle movement that can better simulate the macroscopic characteristics of vehicle flow.

[0008] S2. Based on the orderly movement of the vehicle queue along the main road, the signal cycle of each intersection along the way is marked in an increasing sequence. The same marking of the signal cycle reflects the spatiotemporal correlation of the vehicle queues on adjacent road sections;

[0009] S3. Use signal cycle markings to index the dynamic traffic demand at each intersection, emphasizing the distinction between traffic from upstream main roads and upstream side roads;

[0010] S4. For each intersection, define the traffic retention volume of the previous signal cycle as the traffic state and construct the traffic dynamic equation.

[0011] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0012] As a preferred technical solution of the present invention: In the dynamic traffic model, it is assumed that vehicles follow the right-hand traffic principle. Consider a one-way traffic path along the main road, where all intersections are controlled by traffic lights. At the same time, it is assumed that for each i∈[K], vehicles can only be controlled by θ i-1 Enter π i , and by θ i Leave, where π represents the set of K road segments contained in the considered path, denoted as π: = [π i :i∈[K]], the path passes through π1, π2, ...π in sequence k ,π i is the i-th road segment of the path; θ represents the set of intersections of the considered path, denoted as θ: = [θ i : i∈[K]∪0], where θ i Connect Pi i and π i+1 , θ0 is the source intersection; [n] represents the set {1, 2, ...n}, and n∈N, N is a natural number; := means defined as.

[0013] As a preferred technical solution of the present invention: Step S1 further includes the following sub-steps:

[0014] S11. For any given vehicle e and time t, use v(t|e) to represent the velocity of e at time t, v i is π i A vehicle is said to be in a free-moving state if its speed is determined by the nominal speed of the road section, i.e., the speed may vary according to the nominal speed of the road section but is not affected by signals.

[0015] S12. Let x(t|e) represent the position of vehicle e at time t. If vehicle e is on the main road at this time, then x(t|e) is the distance from vehicle e to the path source (i.e., the distance to θ0) at time t. If vehicle e is not on the main road, then x(t|e) = ζ, and R is a real number; thus, the position of the vehicle can be represented by the set Indicates; x i From θ0 to θi The distance can be obtained by Calculated, and where l i is π i length;

[0016] S13. Before vehicle e leaves the main road, its position is given by the formula Update is performed, and t>t0, after e leaves, x(e, t) :=ζ.

[0017] As a preferred technical solution of the present invention: the relevant variables in the dynamic traffic model include: vehicle start-up loss time, road capacity, delay, speed limit reduction or no congestion delay when the road narrows.

[0018] As a preferred technical solution of the present invention: Step S2 is specifically as follows:

[0019] The time markers between different intersection signal cycles are expressed as follows: For i = 1, 2, ... K, intersection θ i The signal period is θ on the main road i The time interval between two consecutive green lights at the position; assuming θ i The green light starts at Then there is is a signal cycle, u∈N; let C i represents θ i The collection of all signal cycles; at the same time, use Indicates that in the cycle Consider the path θ on the main road i The red light start time;

[0020] The method of associating the consistent signal cycle index of different intersections and using the index as a time identifier is as follows: use continuous natural numbers to index the signal cycle, for each index n and the intersection's own signal mark u, w, record the index n under θ i Cycle The corresponding θ i+1 Cycle Then w satisfies:

[0021]

[0022] That is, for any given intersection, consecutive signal cycles can be indexed by consecutive natural numbers and have unique values; where σ i Indicates that the vehicle is at θ i Startup loss time, τ i Indicates that the vehicle is moving at a nominal speed v i Through π i the time required;

[0023] Based on the above time stamp representation, for any i<K, the signal period and have the same index if and only if the following conditions are met: vehicle e At the moment θ i Leave the front of the convoy and arrive at θ i+1 If you do not leave the main road before During and Before entering θ i+1 .

[0024] As a preferred technical solution of the present invention: in step S3, the dynamic traffic demand of the intersection based on the cycle index is calculated as follows:

[0025] Given a signal strategy T, period n on θ i The demand is:

[0026]

[0027] in

[0028] Where, Among them, regarding the vehicle set, E i (I) indicates that during I period, the i-1 Enter π i A collection of vehicles, Indicates E i From the branch to π i vehicles (if i=1, they are vehicles on the source main road), Indicates E i Vehicles that remain on the main road (i.e., from π i-1 to π i ); Regarding the signal period, consider θ i ∈θ and a signal period indexed by n∈N, When the cycle index is n, the main road considers the path θ i The actual start time of the green light is the start time of the corresponding cycle; is θ i The nominal starting time of the green light is the starting time after compensating the start loss time, and there is The moment when the red light starts in this cycle; is the green light duration of the cycle, i.e. T is the signal strategy, that is τ i The vehicle is traveling at nominal speed v i Through π iTo simplify the description, in the present invention, except for special references, the green light start time mentioned is the nominal green light start time, and the signals mentioned are signals for controlling the direction.

[0029] As a preferred technical solution of the present invention: step S4 includes the following sub-steps:

[0030] S41. Related descriptive variables include:

[0031] For the state variables on the indexed signal period, the state of the system at time t is defined as the information of the system at time t And in the given In this case, the system changes after time t are independent of the past state; time will also be measured by the corresponding signal cycle index at different locations. That is, the model does not describe the state of all road sections at time t, but the state of all road sections at cycle index n, which is different for different road sections at specific times;

[0032] Assume that given strategy T, intersection θ i (where i∈[K]), the signal period index n∈N and Let π at time t i The set of vehicles in is represented as

[0033] V i (t|T):={e:x i-1 <x(t|e,T)≤x i}

[0034] Where x(t|e, T) is the position of vehicle e at time t under the control of T; T is omitted here for simplicity.

[0035] Assume that the strategy after t is V i (t|T) has no effect, let And control T The vehicle set at time i is expressed as:

[0036]

[0037] In the formula, the vehicle set is in π i Travel at free flow speed and Before leaving π i ;

[0038] Using state variables express Time π i The number of vehicles, then

[0039]

[0040] Where, and For vehicles in Leaving θ during the period i The two time points of i and θ i-1 The signal changes and affects how the two teams move from θ during I i The two convoys came from π i-1 and from π i Vehicles with emissions from rather than As θ i The time point of the state variable of the nth cycle is used to obtain the dynamic equation containing only a single traffic load case; for ease of description, N n A tuple representing the state variables of the nth cycle for The independent variable input; What it actually means is that without deceleration Arrival time θ i , but because the red light is actually at π i Number of vehicles stranded;

[0041] S42. Regarding the relationship between traffic demand and index cycle:

[0042] If the start time of the nth cycle is no later than That is, the vehicle Time to leave θ i-1 and reaches θ at free flow velocity i At the moment, the state variable It may be possible to enter the intersection θ at the beginning of the cycle i But because θ i The traffic signal affects the road section π i The vehicles in the i The parameter in is a right-open interval, so that Arriving vehicles are excluded from If the period starts later than The number of vehicles stuck at a red light during the n-1th cycle includes θ i-1 During the nth period from π i-1 Some of the vehicles discharged are also included in a certain θ j (where j<i) in the nth cycle; for this, θ i The corresponding time of the nth period state variable is set to And each vehicle as a traffic demand is counted at most once in each index period n;

[0043] S43. For traffic demand that does not exceed the intersection capacity, the state variable N driven by the incremented cycle index n n The dynamic equation is constructed as follows:

[0044] Given a policy T, for all i∈[K], the state variable N n The dynamic changes satisfy:

[0045]

[0046] Where, in, For cycle

[0047] Index n on θ i The transportation demand of i (I) is the period of time I spent away from π i A collection of vehicles, is θ i Green light nominal start time, is the actual start time of the green light, τ i The vehicle passes π at the nominal speed i The time required; and known Right now For Time period leaves π i The number of vehicles.

[0048] The present invention provides a method for constructing a dynamic traffic model for a signalized trunk road, which has the following beneficial effects: some dynamic changes in the model are driven by asynchronous events representing signal switching at intersections along the trunk road. A new method for defining traffic states is used, with signal cycle index as a time identifier, to describe the interaction between signal switching and the traffic state on which it is based, as well as the resulting traffic response. The method is suitable for real-time signal coordinated control of trunk roads; the representation of signal coordination on the path is simplified, the model scale is small, and the computational complexity is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a flow chart of the method for constructing a dynamic traffic model for a signalized trunk road provided by the present invention.

[0050] Figure 2 Schematic diagram of the spatiotemporal correlation of dynamic traffic demand indexed by signal period. DETAILED DESCRIPTION

[0051] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0052] like Figure 1 As shown, a method for constructing a dynamic traffic model of a signalized trunk road includes the following steps:

[0053] S1. Construct a simplified microscopic model of vehicle movement that can better simulate the macroscopic characteristics of vehicle flow.

[0054] In the dynamic traffic model, it is assumed that vehicles follow the right-hand traffic principle. Consider a one-way traffic path along the main road, and all the intersections along the path are controlled by traffic lights. At the same time, it is assumed that for each i∈[K], the vehicle can only be driven by θ i-1 Enter π i , and by θ i Where π represents the set of K road segments included in the considered path, denoted as π: = [π i :i∈[K]], the path passes through π1, π2, ...π in sequence k ,π i is the i-th road segment of the path; θ represents the set of intersections of the considered path, denoted as θ: = [θ i : i∈[K]∪0], where θ i Connect Pi i and π i+1 , θ0 is the source intersection; l i is π i The length of w i is π i The number of fixed lanes; v i is π i The fixed nominal speed is a stable speed lower than the road speed limit, close to the free flow speed of the road section; x i From θ0 to θ i The distance can be obtained by Calculated, and Where [n] represents the set {1, 2, ... n}, and n∈N, N is a natural number, |a| represents the cardinality of a, a i represents the i-th element of a, := means defined as.

[0055] The vehicle dynamics are described as follows:

[0056] S11. For any given vehicle e and time t, use v(t|e) to represent the velocity of e at time t, v i is π i A vehicle is said to be in a free-moving state if its speed is determined by the nominal speed of the road section, i.e., the speed may vary according to the nominal speed of the road section but is not affected by signals.

[0057] S12. Let x(t|e) represent the position of vehicle e at time t. If vehicle e is on the main road at this time, then x(t|e) is the distance from vehicle e to the path source (i.e., the distance to θ0) at time t. If vehicle e is not on the main road, then x(t|e) = ζ, and R is a real number; thus, the position of the vehicle can be represented by the set Indicates; x i From θ0 to θ i The distance can be obtained by Calculated, and where l i is π i length;

[0058] S13. Before vehicle e leaves the main road, its position is given by the formula Update is performed, and t>t0, after e leaves, x(e,t) :=ζ.

[0059] Regarding the vehicle starting loss time, τ i Indicates that the vehicle passes π at the nominal speed i The time required can be determined by i / v i Calculate; use σ i Indicates that the vehicle is at θ i The starting loss time is equal to the vehicle accelerating from rest to v i The required travel time is related to the speed v i The difference in time required to travel the same distance, assuming: (1)σ i (where i∈[K]) is given; (2) the vehicle starts from v i Accelerate to v i+1 The required time offset is negligible and the length of each road segment in the considered main road is sufficient to complete this acceleration; (3) The vehicle exits the source intersection at v1 and σ0 = 0.

[0060] Regarding road capacity, use r i Represents π i The traffic capacity is defined as π i The vehicles in the queue are at θ i Leaving Pi i The maximum rate of departure increases with the increase of vehicle speed. When leaving π i The vehicle speed reaches v i When r i , in practice this value may be slightly lower than the corresponding rate at the free flow speed on the road;

[0061] If in π i-1 There is a vehicle waiting in front of the stop line, use m i Indicates that when the leaving rate reaches r iBefore stabilizing the value, pass π i-1 The number of vehicles at the stop line; the startup loss σ i In actual situation, m i The time it takes to pass the stop line is the same as the time it takes for all these vehicles to pass the stop line at a speed of r. i The difference between the times taken to pass the stop line.

[0062] Regarding delays, it is assumed that when the speed limit is lowered or the road is narrowed, vehicles are not delayed by congestion; that is, enough vehicles are removed from the main road so that the reduced load can be accommodated by the lower-capacity road section; in this case, unless vehicles are slowed or blocked by a red light or a convoy blocked by a red light, v i Also the vehicle is in π i The actual driving speed in the vehicle is the free flow speed;

[0063] Consider vehicle e at the beginning of the corresponding green light at π i In the queue, assuming that there is mw before e i The queued vehicles, and e leaves π in this cycle i But when leaving π j Before leaving the main road, where j>i, let

[0064]

[0065] Where G i is the intersection θ i The nominal starting time of the green light, σ i Indicates that the vehicle is at θ i Startup loss time, r i is π i The traffic capacity, τ i Indicates that the vehicle is moving at a nominal speed v i Through π i the time required;

[0066] If e reaches θ j The time is later than δ ijm , but at each θ k (i<k<j) The time is δ ikm , then e is said to be leaving π i After the first time in π j Delay (deceleration) occurs on π k A delay occurs on the k-1 Leaving Pi k-1 And in π k The travel time on k , then e is said to be in π k Delay occurs on i is π i The number of fixed lanes.

[0067] Aiming at the needs of arterial road signal control, embodiments can achieve the necessary description of arterial road traffic flow, including vehicle movement, acceleration, delays, and road restrictions.

[0068] S2. Based on the orderly movement of the vehicle queue along the main road, the signal cycle of each intersection along the way is marked in an ascending sequence. The same marking of the signal cycle reflects the spatiotemporal correlation of the vehicle queues on adjacent road sections. The method for constructing the intersection signal cycle index is as follows:

[0069] The relationship between traffic demand and periodic signal must satisfy: for all i, θ i In each signal cycle π i to π i+1 The green light duration in the path direction is greater than the clearing π i The time required for all vehicles in the queue; that is, in θ i In the absence of downstream backflow, traffic demand is lower than the intersection capacity.

[0070] The time markers between different intersection signal cycles are expressed as follows: For i = 1, 2, ... K, intersection θ i The signal period is θ on the main road i The time interval between two consecutive green lights at the position; assuming θ i The green light starts at Then there is is a signal cycle, u∈N; let C i represents θ i The collection of all signal cycles; at the same time, use Indicates that in the cycle Consider the path θ on the main road i The red light start time.

[0071] The method of associating the consistent signal cycle index of different intersections and using the index as a time identifier is as follows: use continuous natural numbers to index the signal cycle, for each index n and the intersection's own signal mark u, w, record the index n under θ i Cycle The corresponding θ i+1 Cycle Then w satisfies

[0072]

[0073] That is, for any given intersection, consecutive signal cycles can be indexed by consecutive natural numbers and have unique values; where σ i Indicates that the vehicle is at θ i Startup loss time, τ i Indicates that the vehicle is moving at a nominal speed v i Through πi The time required.

[0074] Based on the above time stamp representation, for any i<K, the signal period and have the same index if and only if the following conditions are met: vehicle e At the moment θ i Leave the front of the convoy and arrive at θ i+1 If you do not leave the main road before During and Before entering θ i+1 .

[0075] Figure 2 This is a schematic diagram of the spatiotemporal correlation of the signal cycle index dynamic traffic demand in the embodiment. From top to bottom, the movement of the traffic flow in the control direction and the change of the signal light over time. The head of the queue waiting for the red light in each road section is marked in black. The traffic flow movement scenario described is as follows: At the intersection θ i When the green light of index cycle n is turned on, π i-1 The first car in the waiting queue starts to move first; when the first car is adjacent to π i When the last car in the waiting queue is i+1 End the red light of index n-1 and turn on the green light of index period n.

[0076] To further illustrate, given a road segment π i+1 The length l i+1 =2010m, free flow velocity v i+1 =15m / s, startup loss time σ i =σ i+1 = 2s, the signal cycle is 120s, and the green light duration is 50s. i The set of all cycles Let n be a period index variable that satisfies Where t is the time starting from a fixed offset; θ i+1 Cycle and θ i Cycle Same duration, but Compare 10s later, The vehicle starts from a stopped state and accelerates to travel at a free flow speed π i+1 The time required is σ i+1 +l i+1 / v i+1 =2+2010 / 15=136s, satisfy From this there is The index of is n.

[0077] S3. Use signal cycle markings to index the dynamic traffic demand at each intersection, emphasizing the distinction between traffic from upstream main roads and upstream side roads;

[0078] Regarding the representation of signal period: Consider θ i ∈θ and a signal period indexed by n∈N, let The actual start time of the green light, corresponding to the start time of the cycle; is θ i The nominal starting time of the green light is the starting time after the corresponding signal compensates for the start loss time, and there is The moment when the red light starts in this cycle; is the green light duration of the cycle, i.e. T is the signal strategy, that is To simplify the analysis, for all indexes n, let Unless otherwise specified in the present invention, the green light start time mentioned is the nominal green light start time, and the signals mentioned are signals for controlling direction.

[0079] Regarding the interaction between signals and traffic flow, we assume that: (1) once the signal turns red, no vehicle will cross the stop line for the rest of the cycle, except for vehicles that are allowed to turn; (2) for all i∈[K] and all n, where δ i (>0) is the shortest red light duration in a given signal cycle; and If the number of vehicles entering the main road through the intersection branch road when the green light is on in the direction of the main road is small, the impact on traffic can be compensated by vehicles leaving the main road from the upstream intersection; to this end, as long as a vehicle counter is set at the entrance of the corresponding road section, this compensation problem can be solved without calculation.

[0080] Assuming that upstream traffic along the main road direction is dominant, the following restrictions are imposed on the considered signal strategies: for all n and all i∈[k-1],

[0081]

[0082] That is, the traffic demand entering through the branch road is usually less than the traffic demand entering through the upstream section of the main road; for the left inequality, in order to reduce the vehicle spacing, make θ i+1 Signals along the main roads should be on no later than π i All vehicles in the i+1 The light turns red at the moment of the green light, that is, the fleet will pass during the green light period, and the branch traffic will wait for the green light of the next cycle; the inequality on the right side is used to prevent improper signal coordination. At this time, in the cycle with index n, from πi Most of the vehicles coming will be i+1 If we turn it into an equation, then the intersection θ with index n is i+1 The green light is turned on when there are no more oncoming vehicles in the direction of the main road. This can only clear the existing queue but will not form a longer queue. If the inequality is reversed, the gaps between the queues will become larger.

[0083] Assume that the traffic demand satisfies: (1) For all i∈[K], when θ i When the signal along the main road is green, vehicles that are allowed to turn into the corresponding branch road will not enter θ i (e.g. turn right); (2) in θ i-1 Position, enter π from the branch road i The maximum speed of the vehicle is strictly less than r i (3) The time loss caused by the vehicle entering the main road from the branch road due to starting (after the red light on the main road at the intersection) is at least equal to σ i The maximum value of , where i∈[K];

[0084] Given a signal strategy T, for all i∈[K], to describe the intersection θ i The set of vehicles passing a specific location within a given time interval, define the following variables: Let E i (I) indicates that the i-1 Enter π i The set of vehicles, these vehicles are either in I+τ i Leave π during the period i and not in π i deceleration, or leaving π during I i and not in π i Medium deceleration; note E i (I) where I is the corresponding period after deducting the start-up loss time; and if E i (I) is an empty set (e.g. [t1, t2), where t1>t2); D i (I) means leaving π during I period i A collection of vehicles; Respectively represented as E i and D i The vehicles that remain on the main road (the former are from π i-1 to π i , the latter is from π i to π i+1 ); Respectively represented as E i and D i From the branch road to the main roadπ iVehicles (if i = 1, then the vehicles are from the source main road) and vehicles from the main road π i Vehicles leaving the branch road; E i yes and The disjoint union of ; for ease of presentation it is abbreviated as follows:

[0085]

[0086] In the formula, as mentioned above, When the cycle index is n, the main road considers the path θ i The actual start time of the green light, is θ i Green light nominal start time, For the moment when the red light starts in this cycle, is the green light duration of the cycle, i.e. τ i The vehicle is traveling at nominal speed v i Through π i the time required;

[0087] for and relationship, considering At the moment π i The frontmost vehicle in the convoy. Time to leave π i and reaches θ i+1 :If the vehicle does not stop midway, it will Arrival θ i+1 , and there will be So that: (1) Leaving Pi i The vehicle will be at t+τ i+1 Arrival time θ i+1 ; and there is (2)

[0088] The dynamic traffic demand of the intersection based on the cycle index is calculated as follows: given the signal strategy T, the cycle n on θ i The demand is

[0089]

[0090] in

[0091] Where, Among them, regarding the vehicle set, E i (I) indicates that during I period, the i-1 Enter π i A collection of vehicles, Indicates E i The branch reaches π i vehicles (if i=1, they are vehicles on the source main road), Indicates E i Vehicles that remain on the main road (i.e., from π i-1 to π i ); Regarding the signal period, consider θ i ∈θ and a signal period indexed by n∈N, When the cycle index is n, the main road considers the path θ i The actual start time of the green light is the start time of the corresponding cycle; is θ i The nominal starting time of the green light is the starting time after compensating the start loss time, and there is The moment when the red light starts in this cycle; is the green light duration of the cycle, i.e. T is the signal strategy, that is i∈[K],m∈N];τ i Indicates that the vehicle is moving at a nominal speed v i Through π i For the purpose of simplifying the description, in the present invention, unless otherwise specified, the green light start time mentioned is the nominal green light start time, and the signals mentioned are signals for controlling the direction.

[0092] S4. For each intersection, define the traffic retention volume of the previous signal cycle as the traffic state and construct the traffic dynamic equation.

[0093] S41. Related descriptive variables include:

[0094] For the state variables on the indexed signal period, the state of the system at time t is defined as the information of the system at time t And in the given In this case, the system changes after time t are independent of the past state; time will also be measured by the corresponding signal cycle index at different locations, that is, the model does not describe the state of all road sections at time t, but the state of all road sections at cycle index n, which is different for different road sections at different specific times.

[0095] Assume that given strategy T, intersection θ i (where i∈[K]), the signal period index n∈N and Let π at time t i The set of vehicles in is represented as

[0096] V i (t|T):={e:x i-1 <x(t|e,T)≤x i}

[0097] where x(t|e, T) is the position of vehicle e at time t under the control of T; T is omitted here for simplicity.

[0098] Assume that the strategy after t is V i (t|T) has no effect, let And control T Time π i The vehicle set is represented as

[0099]

[0100] The vehicle set is in π i Travel at free flow speed and Before leaving π i .

[0101] Using state variables express Time π i The number of vehicles, then

[0102]

[0103] Where, and For vehicles in Leaving θ during the period i The two time points of i and θ i-1 The signal changes and affects how the two teams move from θ during I i The two convoys came from π i-1 and from π i Vehicles with emissions from rather than As θ i The time point of the state variable of the nth cycle is used to obtain the dynamic equation containing only a single traffic load case; for ease of description, N n A tuple representing the state variables of the nth cycle for The independent variable input; What it actually means is that without deceleration Arrival time θ i , but because the red light is actually at π i The number of stranded vehicles.

[0104] S42. Regarding the relationship between traffic demand and index cycle:

[0105] If the start time of the nth cycle is no later than That is, the vehicle Time to leave θ i-1 and reaches θ at free flow velocity i At the moment, the state variable It may be possible to enter the intersection θ at the beginning of the cycle i But because θ i The traffic signal affects the road section π i The vehicles in the i The parameter in is a right-open interval, so that Arriving vehicles are excluded from If the period starts later than The number of vehicles stuck at a red light during the n-1th cycle includes θ i-1 During the nth period from π i-1 Some of the vehicles discharged are also included in a certain θ j (where j<i) in the nth cycle; for this, θ i The corresponding time of the nth period state variable is set to Each vehicle is counted as a traffic demand at most once in each index period n.

[0106] S43. For traffic demand that does not exceed the intersection capacity, the state variable N driven by the incremented cycle index n n The dynamic equation is constructed as follows:

[0107] Given a policy T, for all i∈[K], the state variable N n The dynamic changes satisfy:

[0108]

[0109] Where, in, is the period index n on θ i The transportation demand of i (I) is the period of time I spent away from π i A collection of vehicles, is θ i Green light nominal start time, is the actual start time of the green light, τ i The vehicle passes π at the nominal speed i Time required; known Right now For Time period leaves π i The number of vehicles.

[0110] Based on the signal cycle index, the embodiment obtains the dynamic changes of traffic conditions according to the temporal and spatial relationship of the associated traffic flows and signals.

[0111] The above-mentioned specific implementation methods are used to illustrate the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the scope of protection of the claims shall fall within the scope of protection of the present invention.

Claims

1. A method for constructing a dynamic traffic model for a signalized trunk road, characterized by: The steps include: S1. Construct a simplified microscopic model of vehicle movement that can better simulate the macroscopic characteristics of vehicle flow. S2. Based on the orderly movement of the vehicle queue along the main road, the signal cycle of each intersection along the way is marked in an increasing sequence. The same marking of the signal cycle reflects the temporal and spatial correlation of the vehicle queues on adjacent road sections; S3. Use signal cycle markings to index the dynamic traffic demand at each intersection, emphasizing the distinction between traffic from upstream main roads and upstream side roads; S4. For each intersection, define the traffic retention volume of the previous signal cycle as the traffic state and construct the traffic dynamic equation.

2. The method for constructing a dynamic traffic model for a signalized trunk road according to claim 1, characterized in that: In the dynamic traffic model, it is assumed that vehicles follow the right-hand traffic principle. Consider a one-way traffic path along the main road, where all intersections are controlled by traffic lights. At the same time, it is assumed that for each i∈[K], vehicles can only be controlled by θ i-1 Enter π i , and by θ i Leave, where π represents the set of K road segments contained in the considered path, denoted as π: = [π i :i∈[K]], the path passes through π1, π2, ...π in sequence k ,π i is the i-th road segment of the path; θ represents the set of intersections of the considered path, denoted as θ:=[θ i :i∈[K]∪0], where θ i Connect Pi i and π i+1 , θ0 is the source intersection; [n] represents the set {1, 2, ...n}, and n∈N, N is a natural number; := means defined as.

3. The method for constructing a dynamic traffic model for a signalized trunk road according to claim 1, characterized in that: Step S1 also includes the following sub-steps: S11. For any given vehicle e and time t, use v(t|e) to represent the velocity of e at time t, v i is π i A vehicle is said to be in a free-moving state if its speed is determined by the nominal speed of the road section, i.e., the speed may vary according to the nominal speed of the road section but is not affected by signals. S12. Let x(t|e) represent the position of vehicle e at time t. If vehicle e is on the main road at this time, then x(t|e) is the distance from vehicle e to the path source (i.e., the distance to θ0) at time t. If vehicle e is not on the main road, then x(t|e) = ζ, and R is a real number; thus, the position of the vehicle can be represented by the set Indicates; x i From θ0 to θ i The distance can be obtained by Calculated, and where l i is π i length; S13. Before vehicle e leaves the main road, its position is given by the formula Update is performed, and t>t0, after e leaves, x(e, t) :=ζ.

4. The method for constructing a dynamic traffic model for a signalized trunk road according to claim 1, characterized in that: The relevant variables in the dynamic traffic model include vehicle start-up loss time, road capacity, delays, and congestion-free delays when speed limits are reduced or roads are narrowed.

5. The method for constructing a dynamic traffic model for a signalized trunk road according to claim 1, characterized in that: Step S2 is specifically as follows: The time markers between different intersection signal cycles are expressed as follows: For i = 1, 2, ... K, intersection θ i The signal period is θ on the main road i The time interval between two consecutive green lights at the position; assuming θ i The green light starts at Then there is is a signal cycle, u∈N; let C i represents θ i The collection of all signal cycles; at the same time, use Indicates that in the cycle Consider the path θ on the main road i The red light start time; The method of associating the consistent signal cycle index of different intersections and using the index as a time identifier is as follows: use continuous natural numbers to index the signal cycle, for each index n and the intersection's own signal mark u, w, record the index n under θ i Cycle The corresponding θ i+1 Cycle Then w satisfies: That is, for any given intersection, consecutive signal cycles can be indexed by consecutive natural numbers and have unique values; where σ i Indicates that the vehicle is at θ i Startup loss time, τ i Indicates that the vehicle is moving at a nominal speed v i Through π i the time required; Based on the above representation of the time identifier, for any i < K, the signal period and have the same index if and only if the following conditions are met: Vehicle e leaves the front of the platoon at time at θ i , and does not leave the main road before reaching θ i+1 , and will enter θ during and before reaching θ i+1 .

6. The method for constructing a dynamic traffic model for a signalized trunk road according to claim 1, characterized in that: In step S3, the dynamic traffic demand at the intersection based on the cycle index is calculated as follows: Given a signal strategy T, period n on θ i The demand is: in Where, Among them, regarding the vehicle set, E i (I) indicates that during I period, the i-1 Enter π i A collection of vehicles, Indicates E i The branch reaches π i vehicles (if i=1, they are vehicles on the source main road), Indicates E i Vehicles that remain on the main road (i.e., from π i-1 to π i ); Regarding the signal period, consider θ i ∈θ and a signal period indexed by n∈N, When the cycle index is n, the main road considers the path θ i The actual start time of the green light is the start time of the corresponding cycle; is θ i The nominal starting time of the green light is the starting time after compensating the start loss time, and there is The moment when the red light starts in this cycle; is the green light duration of the cycle, i.e. T is the signal strategy, that is τ i Indicates that the vehicle is moving at a nominal speed v i Through π i For the purpose of simplifying the description, in the present invention, unless otherwise specified, the green light start time mentioned is the nominal green light start time, and the signals mentioned are signals for controlling the direction.

7. The method for constructing a dynamic traffic model for a signalized trunk road according to claim 1, characterized in that: Step S4 includes the following sub-steps: S41. Related descriptive variables include: For the state variables on the indexed signal period, the state of the system at time t is defined as the information of the system at time t And in the given In this case, the system changes after time t are independent of the past state; time will also be measured by the corresponding signal cycle index at different locations. That is, the model does not describe the state of all road sections at time t, but the state of all road sections at cycle index n, which is different for different road sections at specific times; Assume that given strategy T, intersection θ i , where i∈[K], signal period index n∈N and Let π at time t i The set of vehicles in is represented as V i (t|T):={e:x i-1 <x(t|e,T)≤x i } Where x(t|e, T) is the position of vehicle e at time t under the control of T; T is omitted here for simplicity. Assume that the strategy after t is V i (t|T) has no effect, let And control T Time π i The vehicle set is represented as: In the formula, the vehicle set is in π i Travel at free flow speed and Before leaving π i ; Using state variables express Time π i The number of vehicles, then Where, and For vehicles in Leaving θ during the period i The two time points of i and θ i-1 The signal changes and affects how the two teams move from θ during I i The two convoys came from π i-1 and from π i Vehicles with emissions from rather than As θ i The time point of the state variable of the nth cycle is used to obtain the dynamic equation containing only a single traffic load case; for ease of description, N n A tuple representing the state variables of the nth cycle for The independent variable input; What it actually means is that without deceleration Arrival time θ i , but because the red light is actually at π i Number of vehicles stranded; S42. Regarding the relationship between traffic demand and index cycle: If the start time of the nth cycle is no later than That is, the vehicle Time to leave θ i-1 and reaches θ at free flow velocity i At the moment, the state variable It may be possible to enter the intersection θ at the beginning of the cycle i But because θ i The traffic signal affects the road section π i The vehicles in are included; if the cycle starts later than The number of vehicles stuck at a red light during the n-1th cycle includes θ i-1 During the nth period from π i-1 Some of the vehicles discharged are also included in a certain θ j In the state of the nth cycle, where j<i; for this, θ i The corresponding time of the nth period state variable is set to And each vehicle as a traffic demand is counted at most once in each index period n; S43. For traffic demand that does not exceed the intersection capacity, the state variable N driven by the incremented cycle index n n The dynamic equation is constructed as follows: Given a policy T, for all i∈[K], the state variable N n The dynamic changes satisfy: Where, in, As mentioned before, for period index n on θ i The transportation demand of i (I) is the period of time I spent away from π i A collection of vehicles, is θ i Green light nominal start time, is the actual start time of the green light, τ i The vehicle passes π at the nominal speed i The time required; and known Right now For Time period leaves π i The number of vehicles.

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