Highway main line variable speed limit and entrance ramp cooperative control method

Abstract

The invention relates to an expressway main line variable speed limit and entrance ramp cooperative control method, and relates to the technical field of traffic management and control. Comprising the steps of predicting traffic flow operation data, calculating a congestion propagation length, determining a main line variable speed limit area, selecting an active control strategy, evaluating a control effect, optimizing a control scheme and a lower control scheme. According to the main line variable speed limit and entrance ramp variable speed limit linkage control strategy for speed limit interval dynamic optimization, the fixed speed limit area and the dynamic speed limit area are arranged on the main line, the opening condition of the speed limit areas is dynamically adjusted according to the congestion propagation condition, the interval length of the main line variable speed limit interval is dynamically adjusted, and the speed limit speed limit effect is improved. Therefore, the variable speed limit area of the main line is adjusted and the control strategy is optimized, so that the problem of speed limit failure caused by insufficient length of the variable speed limit area of the main line under the condition of large-range congestion caused by short-time large flow is solved, and the problem that the upstream passing benefit is reduced due to the overlong variable speed limit area of the main line under the condition of local congestion is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of traffic management and control, and in particular to a method for coordinated control of variable speed limit and entrance ramp of a main line of an expressway. Background Art

[0002] With the annual growth of car ownership, the contradiction between limited road space and growing travel demand has become increasingly intensified, and the problem of highway congestion has become prominent. Effective control measures are urgently needed to alleviate traffic congestion. Entrance ramp signal control and main line variable speed limit control are commonly used traffic control measures. Ramp signal control controls the number of vehicles entering the main line through signal lights, and variable speed limit controls speed limits in some areas of the main line to adjust the arrival distribution of vehicles upstream of the main line.

[0003] Based on the classic ramp control method, combined with the main line variable speed limit control, a main line and ramp collaborative control method has emerged. For the main line variable speed limit, the existing technology mainly adopts a fixed interval control method, and sets the main line speed limit interval length according to the common traffic conditions and actual speed limit requirements in daily traffic management of expressways. However, the fixed interval variable speed limit cannot meet the speed limit requirements in different congestion scenarios. In a large-scale congestion scenario, a short-term large flow input is input upstream of the main line. If the length of the main line variable speed limit area is insufficient, the probability of speed limit failure increases. For local congestion scenarios, a long-distance fixed interval variable speed limit limits the speed of vehicles upstream of the main line, resulting in a loss of upstream traffic benefits. To this end, we propose a method for collaborative control of the variable speed limit and entrance ramp of the main line of a highway. Summary of the invention

[0004] The object of the present invention is to provide a method for coordinated control of variable speed limit and entrance ramp of a highway main line.

[0005] The technical problem solved by the present invention is that the variable speed limit in a fixed interval adopted in the prior art cannot meet the speed limit requirements in different congestion scenarios.

[0006] The present invention can be implemented by the following technical solution: A method for coordinated control of variable speed limit and entrance ramp on a main line of a highway, comprising the following steps:

[0007] Step 1: Build a METANET prediction model and C T C Traffic flow operation data prediction K at the moment C T C to (K C +N P )T C Traffic flow operation data within the time interval, where T C , K C 、N Pare the controller time step, controller cycle number, and prediction cycle of the prediction model, respectively;

[0008] Step 2: Set the congestion propagation rules and calculate the congestion propagation length based on the traffic flow operation data predicted by the model;

[0009] Step 3: Determine the variable speed limit area on the main line according to the congestion propagation length;

[0010] Step 4: Based on the different ranges of the main line variable speed limit areas, select the main line dynamic interval variable speed limit and single / multiple entrance ramp linkage control method:

[0011] The main line dynamic section variable speed limit and single entrance ramp linkage control method is an optimization control method that takes the maximum total vehicle travel distance in the congested sub-area as the optimization target;

[0012] The main line dynamic section variable speed limit and multi-entry ramp linkage control method is a double-layer optimization control method that takes the maximum total driving distance of vehicles in the multi-ramp system as the upper optimization target and the maximum total driving distance of vehicles in the control sub-area as the lower optimization target.

[0013] Step 5: Select the total driving distance of vehicles in the variable speed limit area of ​​the main line within the control period as an evaluation index to evaluate the control effect of the above-mentioned optimization control method;

[0014] Step 6: Solve the optimization objective function of the optimization control method matching different congestion scenarios in step 4 to obtain the optimal control sequence within the control period, specifically the entrance ramp adjustment amount and the speed limit value of the main line variable speed limit area;

[0015] Step 7: Send the first element in the optimal control sequence to the system to implement linkage control of the variable speed limit in the dynamic section of the main line and the single / multiple entrance ramps; repeat the above steps at the next control moment.

[0016] A further technical improvement of the present invention is that the METANET prediction model formula includes:

[0017]

[0018] q i (k) = ρ i (k)v i (k)λ i ;

[0019] Among them, ρ i (k+1) and ρ i (k) are the densities of section i in the k+1th control cycle and the kth control cycle, Δt is the statistical time interval, L i is the length of road section i, λ iis the number of lanes in road section i, q i-1 (k) and q i (k) are the flow rates of section i-1 and section i in the kth control cycle, r i (k) is the entrance ramp adjustment value of the kth control cycle, s i (k) is the outflow of the exit ramp in the kth control cycle, v free,i is the free flow velocity, v i (k) is the speed of section i in the kth control cycle, α m is the fitting coefficient, ρ c,i is the critical density of road section i; V(ρ i (k)) is the expected speed of road section i under the current density, v vsl,i (k) is the variable speed limit value of section i in the kth control cycle, which is obtained by solving the optimization model; T is the control step size; τ is the driver's response time to traffic density perception; η is the expected parameter; κ is the elasticity coefficient.

[0020] A further technical improvement of the present invention is that the method for obtaining the congestion propagation length in step 2 specifically includes:

[0021] When the average speed of vehicles in a sub-section within a certain control cycle is less than the set congestion threshold, the sub-section is determined to be congested and marked, and vice versa;

[0022] After completing the congestion status marking of all sub-road sections, the congestion propagation length that meets the congestion propagation rule within the control period is statistically calculated.

[0023] A further technical improvement of the present invention is that the congestion propagation rule includes:

[0024] The congested area needs to satisfy spatiotemporal continuity;

[0025] The congestion propagation direction is upstream;

[0026] The congestion area boundaries need to be continuous.

[0027] A further technical improvement of the present invention is that: in step 3, the main line variable speed limit area A is determined vsl The methods include:

[0028] Assume that the congestion propagation length in the kth control period is L jam (k), the congestion sub-area is numbered as p, the upstream control sub-area of ​​the congestion sub-area is p-1, and the connection length between the congestion sub-area and the upstream control sub-area is L r , the buffer area in each control sub-area is A b , the buffer length is L b ; Fixed speed limit zone is A f , the length of the fixed speed limit area is Lf ; The kth sub-area in the main line dynamic variable speed limit section is A d,k , the length of a single main line dynamically variable speed limit sub-area is L d The number of the dynamic variable speed limit sub-area in the center of the main line dynamic variable speed limit section is n d ; then the main line variable speed limit area A vsl The formula is expressed as:

[0029]

[0030] in, is the fixed speed limit area of ​​the pth control sub-area, is the jth main line dynamically variable speed limit sub-area of ​​the pth control sub-area, is the fixed speed limit area of ​​the p-1th control sub-area, is the jth main line dynamically variable speed limit sub-area of ​​the p-1th control sub-area; the minimum value of p is an integer 1;

[0031] When p is 1, it means that congestion is propagating in a single control sub-area. At this time:

[0032]

[0033] A further technical improvement of the present invention is that when p=1, a main line dynamic section variable speed limit and a single entrance ramp linkage control method are selected; when p>1, a main line dynamic section variable speed limit and a multi-entry ramp linkage control method are selected.

[0034] The further technical improvement of the present invention is: a main line dynamic section variable speed limit and single entrance ramp linkage control method, specifically including:

[0035] Set the optimization goal: select the maximum total driving distance of vehicles in the congested sub-area p as the optimization goal;

[0036] Set up constraints:

[0037] (1) When A vsl =[A f ] p When , the main line speed limit area of ​​the congested sub-area is a fixed speed limit area:

[0038] The speed limit value of the congested sub-area p in the fixed speed limit area of ​​the main line of a certain control period should be within the set threshold, that is, the variable speed limit value constraint of the fixed speed limit area;

[0039] The speed limit difference of the congested sub-area p in the main line fixed speed limit area of ​​two adjacent control periods should be within the set threshold, that is, the speed limit difference constraint of adjacent control periods;

[0040] The upstream traffic volume of the main line should be less than the dynamic capacity of the bottleneck location;

[0041] (2) When A vsl =[A f ,A d,j ] p When the speed limit area of ​​the main line in the congested sub-area is fixed and dynamic speed limit areas:

[0042] The variable speed limit value constraint is met in both the fixed speed limit area and the dynamic speed limit area;

[0043] The speed limit difference constraint of adjacent control cycles is satisfied in both the fixed speed limit area and the dynamic speed limit area;

[0044] The safe collision time is not less than the safe collision time threshold, that is, the speed limit value constraint of the adjacent variable speed limit area; the safe collision time is the ratio of the longitudinal distance of the leading vehicle in the adjacent dynamic variable speed limit sub-area in the dynamic speed limit area to the speed limit difference of the adjacent dynamic variable speed limit sub-area;

[0045] Satisfy the entrance ramp signal control constraints of the congested sub-area, including cycle time constraints, green light time constraints and entrance ramp queue length constraints.

[0046] The further technical improvement of the present invention is: a main line dynamic section variable speed limit and multi-entry ramp linkage control method, specifically including:

[0047] Set optimization goals:

[0048] Upper-level optimization goal: The total distance traveled by vehicles in a multi-ramp system is maximized;

[0049] Lower-level optimization goal: maximize the total driving distance of vehicles in the control sub-area;

[0050] Set constraints: Upper constraint: The upstream outflow of the main line is less than the dynamic capacity of the bottleneck position of the congested sub-area; Lower constraint:

[0051] (1) When A vsl ={[A f ,A d,{1,2,...,n]} ] p ,[A f ,A d,{1,2,...,n]} ] p-1 ...[A f ] 1}, the main line speed limit area of ​​the congested sub-area is a fixed speed limit area and a dynamic speed limit area, and the main line speed limit area of ​​the congested upstream sub-area is a fixed speed limit area:

[0052] The congested sub-area satisfies the variable speed limit value constraint, the speed limit difference constraint of adjacent control cycles, and the speed limit value constraint of adjacent variable speed limit areas in the fixed speed limit area and the dynamic speed limit area; the congested upstream sub-area satisfies the variable speed limit value constraint and the speed limit difference constraint of adjacent control cycles in the fixed speed limit area;

[0053] (2) When A vsl ={[A f ,A d, { 1,2,...,n]}] p ,[A f ,A d, { 1,2,...,n]}] p-1 ...[A f ,A d,j ] 1}, the mainline speed limit areas in the congested sub-area and the congested upstream sub-area are both fixed speed limit areas and dynamic speed limit areas:

[0054] The fixed speed limit area and dynamic speed limit area in the congested sub-area and the congested upstream sub-area all meet the variable speed limit value constraints of the speed limit area, the speed limit difference constraints of adjacent control cycles, and the speed limit value constraints of adjacent variable speed limit areas.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The present invention proposes a main line variable speed limit and entrance ramp variable speed limit linkage control strategy with dynamic optimization of speed limit intervals. By setting fixed speed limit areas and dynamic speed limit areas on the main line, the opening of the speed limit areas is dynamically adjusted according to the congestion propagation situation in the actual congestion scenario, so that the interval length of the main line variable speed limit interval can be dynamically adjusted according to the actual congestion situation, and then the main line variable speed limit area and the optimization control strategy are adjusted, which well solves the speed limit failure problem caused by insufficient length of the main line variable speed limit area in the case of large-scale congestion caused by short-term large flow, and the problem of reduced upstream traffic efficiency caused by excessively long main line variable speed limit intervals in local small-scale congestion. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0058] Figure 1 It is a schematic diagram of the method flow of the present invention;

[0059] Figure 2 It is a schematic diagram of the expressway partition state under two control sub-areas of the present invention. DETAILED DESCRIPTION

[0060] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0061] See also Figure 1-2As shown, a method for coordinated control of variable speed limit and entrance ramp on a main line of a highway specifically includes the following steps:

[0062] Step 1: Predict traffic flow operation data

[0063] Assume that the prediction time of the prediction model is T P , the prediction time step number is K P , the prediction period is N P ; The controller time step is T C , the controller cycle number is K C , the control period is N C ;

[0064] Based on K C T C The traffic operation data at each moment and the METANET prediction model are used to predict K C T C to (K C +N P )T C Traffic flow operation data;

[0065] Among them, the METANET prediction model formula is as follows:

[0066]

[0067] q i (k) = ρ i (k)v i (k)λ i (4)

[0068] ρ i (k+1) and ρ i (k) are the densities of section i in the k+1th control cycle and the kth control cycle, Δt is the statistical time interval, L i is the length of road section i, λ i is the number of lanes in road section i, q i-1 (k) and q i (k) are the flow rates of section i-1 and section i in the kth control cycle, r i (k) is the entrance ramp adjustment value of the kth control cycle, s i (k) is the outflow of the exit ramp in the kth control cycle, v free,i is the free flow velocity, v i (k) is the speed of section i in the kth control cycle, α m is the fitting coefficient, ρ c,i is the critical density of road section i; V(ρ i (k)) is the expected speed of road section i under the current density, v vsl,i(k) is the variable speed limit value of section i in the kth control cycle, obtained by solving the optimization model; T is the control step size;

[0069] τ is the driver's response time to traffic density, usually 2s; η is the expected parameter, usually 40; κ is the elasticity coefficient, usually 20.

[0070] Step 2: Calculate the congestion propagation length

[0071] The congestion propagation length is calculated based on the predicted traffic flow operation data and congestion propagation rules. The specific calculation process includes:

[0072] S21, formulate a congestion standard based on the average speed of the sub-segment i in the kth control cycle. When the average speed of the sub-segment is less than the congestion threshold, it is considered that the sub-segment is congested and marked as 1; otherwise, it is marked as 0;

[0073] Right now:

[0074] S22. Formulate congestion propagation rules. The specific rules are as follows: ① The congestion area must meet the requirements of spatiotemporal continuity; ② The congestion propagation direction is the upstream direction; ③ The boundaries of the congestion area must be continuous;

[0075] S23: After the congestion status of all sub-segments is marked, the congestion propagation length L of the kth control cycle is calculated according to the congestion propagation rule. jam (k).

[0076] Step 3: Determine the variable speed limit area on the main line

[0077] refer to Figure 2 Taking two control sub-areas as an example, the main line variable speed limit area A is determined based on the congestion propagation length. vsl ;

[0078] Assume that the congestion propagation length in the kth control period is L jam (k), the congestion sub-area is numbered as p, the upstream control sub-area of ​​the congestion sub-area is p-1, and the connection length between the congestion sub-area and the upstream control sub-area is L r , the buffer area in each control sub-area is A b , the buffer length is L b ; Fixed speed limit zone is A f , the length of the fixed speed limit area is L f ; The kth sub-area in the main line dynamic variable speed limit section is A d,k , the length of a single main line dynamically variable speed limit sub-area is L d ;

[0079] The specific steps for determining the dynamic variable speed limit section of the main line under different congestion scenarios are as follows:

[0080] S31. When congestion propagates in a single control sub-area, the method for determining the variable speed limit area on the main line is as follows:

[0081] in, is the fixed speed limit area of ​​the pth control sub-area, is the jth main line dynamic variable speed limit sub-area of ​​the pth control sub-area, n d It is the number of the main line dynamic variable speed limit sub-zone.

[0082] S32. When congestion propagates to the upstream entrance ramp of the congested sub-area, the method for determining the variable speed limit area of ​​the main line is as follows:

[0083]

[0084] in, is the fixed speed limit area of ​​the p-1th control sub-area, It is the jth main line dynamically variable speed limit sub-area of ​​the p-1th control sub-area.

[0085] For the case where congestion spreads across more than two sub-areas, the method for determining the variable speed limit area on the main line can be expressed as follows, where p is a positive integer:

[0086]

[0087] Step 4: Select an active control method

[0088] Based on the variable speed limit area of ​​the main line, the main line dynamic interval variable speed limit and single / multiple entrance ramp linkage control method are selected:

[0089] When the main line variable speed limit area only includes the speed limit area where the congestion sub-area is located, that is, A vsl ={[A f ] p} or A ASL ={[A f ,A d,j ] p}, select the main line dynamic section variable speed limit and single entrance ramp linkage control method;

[0090] When the main line variable speed limit area includes more than one speed limit area where the congestion sub-area is located, that is, A vsl ={[A f ,A d,{1,2,...,n]} ] p ,[A f ,A d,{1,2,...,n]} ] p-1 ...[A f ] 1} or A vsl ={[Af ,A d,{1,2,...,n]} ] p ,[A f ,A d,{1,2,...,n]} ] p-1 ...[A f ,A d,j ] 1}, select the main line dynamic interval variable speed limit and multi-entry ramp linkage control method.

[0091] 1. The main line dynamic section variable speed limit and single entrance ramp linkage control method are as follows:

[0092] (1) Setting optimization goals

[0093] The optimization goal mainly considers the traffic operation efficiency of the congested sub-area, and the maximum total driving distance of vehicles in the congested sub-area p is selected as the optimization goal, that is:

[0094]

[0095] Among them, ρ i (k) is the density of section i in the kth control cycle, L j is the length of section i, T is the control step length, v i (k) is the speed of section i in the kth control cycle; R p (k) is the entrance ramp adjustment value of the pth control sub-area in the kth control cycle, is the speed of the entrance ramp of the p-th control sub-area in the k-th control cycle.

[0096] (2) Setting constraints

[0097] ①If A vsl =[A f ] p , at this time, the main line speed limit area of ​​the congested sub-area is a fixed speed limit area, and the constraint conditions need to consider the variable speed limit value constraint of the speed limit area and the speed limit difference constraint of adjacent control cycles, that is:

[0098]

[0099] in, and are the speed limits of the congested sub-area p in the main line fixed speed limit area in the kth and k-1th control cycles, v min and v max are the minimum and maximum values ​​of the variable speed limit on the main line respectively; and in general, v min Take 40km / h, v max Take 120km / h, v dif Take 20km / h.

[0100] In addition, to avoid congestion spreading upstream of the main line, the traffic volume upstream of the main line should be less than the dynamic capacity of the bottleneck location, that is:

[0101]

[0102] Among them, q i (k) is the upstream traffic flow of the congested area in the kth control period; C jam (k) is the dynamic traffic capacity of the congested area in the kth control cycle.

[0103] ②If A vsl =[A f ,A d,j ] p At this time, the main line speed limit area of ​​the congested sub-area is a fixed and dynamic speed limit area. On the basis of considering the variable speed limit value constraint of the speed limit area and the speed limit difference constraint of adjacent control cycles, it is necessary to constrain the speed limit value of the adjacent speed limit area of ​​the main line. It is necessary to further constrain the speed limit value of the adjacent variable speed limit area of ​​the main line from the perspective of safe collision to avoid traffic accidents caused by the speed disharmony of the adjacent variable speed limit areas of the main line;

[0104] This application selects the safe collision time TTC as the safe collision evaluation index, and constrains the speed limit value of the adjacent variable speed limit area according to the TTC threshold of the leading vehicle in the adjacent variable speed limit area. The specific constraint conditions are as follows:

[0105]

[0106] in, is the longitudinal position of the head vehicle of the j+1th dynamic variable speed limit sub-area on the main line in the control sub-area p of the kth control cycle; is the longitudinal position of the head vehicle of the jth dynamically variable speed limit sub-area on the main line in the control sub-area p of the kth control cycle; is the speed limit value of the jth dynamically variable speed limit sub-area of ​​the main line in the control sub-area p of the kth control cycle; is the speed limit value of the j+1th dynamically variable speed limit sub-area of ​​the main line in the control sub-area p of the kth control cycle; TTC * is the safety collision time threshold, which is usually 4s.

[0107] The calculation method is:

[0108] Similarly, x p,j+1 (k) = x p,j+1 (k-1)+v vsl,p,j+1 (k-1)×T.

[0109] For the entrance ramp signal control, the main constraints are from the aspects of cycle time, green light time and entrance ramp queue length, as follows:

[0110] C min ≤C(k)≤C max (14)

[0111] g min ≤g(k)≤g max (15)

[0112] L p (k)≤L q * (16)

[0113] Wherein, C(k) is the cycle length of the kth control cycle, C(k)=3600 / R(k); C min is the minimum cycle length, usually 60s; C max The maximum cycle duration is usually 120s;

[0114] g(k) is the green light duration of the kth control cycle, and g(k)=r(k)×C(k) / S r , S r is the saturated flow rate of the entrance ramp, generally 500pcu / h, g min The minimum green light duration is usually 30s. max The maximum green light duration is usually 60s;

[0115] L p (k) is the estimated queue length of the entrance ramp of the control sub-area p in the kth control cycle, L q * is the maximum queue length, L p (k) The calculation formula is:

[0116]

[0117] Among them, L p (k-1) is the length of the vehicle queue at the entrance ramp of the control sub-area p in the k-1th control cycle, is the number of vehicles arriving at the entrance ramp of the control sub-area p in the kth control cycle, L car is the vehicle length.

[0118] 2. The main line dynamic section variable speed limit and multi-entry ramp linkage control method are as follows:

[0119] (1) Setting optimization goals

[0120] The optimization goal comprehensively considers the traffic efficiency of the system and each control sub-area;

[0121] The upper optimization goal is to maximize the total driving distance of vehicles in the multi-ramp system, that is:

[0122]

[0123] The lower optimization goal is to maximize the total driving distance of vehicles in the control sub-area, that is:

[0124]

[0125] Among them, m p is the number of control sub-areas calculated based on the congestion propagation length, R p (k) is the entrance ramp adjustment value of the pth control sub-area in the kth control cycle.

[0126] (2) Setting constraints

[0127] The upper-level constraint condition should ensure that the upstream outflow of the main line should be less than the dynamic capacity of the bottleneck position of the congested sub-area, that is:

[0128] in, is the upstream outflow of the main line at the bottleneck location of the congested sub-area, C i (k) is the dynamic capacity of the bottleneck location; and

[0129] R p-1 (k) is the ramp adjustment value of the p-1th control sub-area in the kth control cycle; is the outflow of the exit ramp of the p-1th control sub-area in the kth control period; is the flow rate of the variable speed limit area of ​​the main line in the p-1th control sub-area in the kth control cycle, is the flow rate of the normal driving area of ​​the main line in the p-1th control sub-area in the kth control cycle,

[0130]

[0131] For the lower level constraints: If A vsl ={[A f ,A d,(1,2,...,n) ] p ,[A f ] p-1}, at this time, the main line speed limit area of ​​the congested sub-area is a fixed speed limit area and a dynamic speed limit area, and the main line speed limit area of ​​the congested upstream sub-area is a fixed speed limit area; the speed limit constraint conditions of the congested sub-area are the variable speed limit value of the speed limit area, the speed limit difference of adjacent control cycles, and the speed limit value constraint of adjacent variable speed limit areas, as shown in formulas (9)-(12);

[0132] The speed limit constraint conditions of the congested upstream sub-area are the variable speed limit value of the speed limit area and the speed limit difference of adjacent control cycles, as shown in formulas (9)-(10);

[0133] If A vsl ={[A f ,A d,(1,2,...,n) ] p ,[A f ] p-1 ,[A f ,A d,j ] p-1}, at this time, the main line speed limit areas of the congested sub-area and the congested upstream sub-area are both fixed speed limit areas and dynamic speed limit areas. The speed limit constraints of the congested sub-area and the congested upstream sub-area are the variable speed limit value of the speed limit area, the speed limit difference of adjacent control cycles, and the speed limit value constraints of adjacent variable speed limit areas, as shown in formulas (9)-(12).

[0134] To maintain the integrity of the active control method, the on-ramp constraints of each control sub-area are consistent with the mainline dynamic interval variable speed limit and the linkage control of the single on-ramp.

[0135] Step 5: Select evaluation indicators to evaluate the control effect

[0136] For the main line dynamic section variable speed limit and single entrance ramp linkage control, the total driving distance of vehicles in the congested sub-area within the control period is selected as the control effect evaluation index; for the main line dynamic section variable speed limit and multi-entry ramp linkage control, the total driving distance of vehicles in the multi-ramp system and the total driving distance of vehicles in each control sub-area within the control period are selected as the control effect evaluation index; the greater the total driving distance of vehicles, the better the control effect.

[0137] Step 6: Optimize control scheme

[0138] The optimization objective function under different active control methods is solved to obtain the optimal control sequence {u(k c ),u(k c +1),...,u(k c +N c -2),u(k c +N c -1)}.

[0139] 1) For the main line dynamic section variable speed limit and single entrance ramp linkage control, u=[R,v vsl,j ] p . Where R p is the entrance ramp adjustment, The speed limit value of the jth variable speed limit area of ​​the main line, j = 0, 1, 2, 3, .... j = 0 represents a fixed speed limit area in the control sub-area, and j = 0, 1, 2, 3, ... represents a dynamically variable speed limit area in the control sub-area.

[0140] 2) For the main line dynamic section variable speed limit and multi-entry ramp linkage control, u=[R,v vsl,j ] p,p-1 Among them, R p-1 is the entrance ramp regulation value of the p-1th control sub-area, is the speed limit value of the jth variable speed limit area of ​​the main line of the p-1th control sub-area, j=0,1,2,3...

[0141] Step 7: Issue the control plan

[0142] The first element u(k c ) is sent to the control system. For the main line dynamic section variable speed limit and single entrance ramp linkage control, For the main line dynamic section variable speed limit and multi-entry ramp linkage control, u(k c )=[R(k c ),v vsl,j (k c )] p,p-1 .

[0143] At the next control moment (k c +1)T c , repeat the whole process of vehicle speed and position prediction, control scheme evaluation, control scheme optimization, and control scheme issuance.

[0144] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for coordinated control of variable speed limit and entrance ramp on a main line of a highway, characterized in that: The steps include: Step 1: Build a METANET prediction model and C T C Traffic flow operation data prediction K at the moment C T C to (K C +N P )T C Traffic flow operation data within the time interval, where T C , K C 、N P are the controller time step, controller cycle number, and prediction cycle of the prediction model, respectively; Step 2: Set the congestion propagation rules and calculate the congestion propagation length based on the traffic flow operation data predicted by the model; Step 3: Determine the variable speed limit area on the main line according to the congestion propagation length; Step 4: Based on the different ranges of the main line variable speed limit areas, select the main line dynamic interval variable speed limit and single / multiple entrance ramp linkage control method: The main line dynamic section variable speed limit and single entrance ramp linkage control method is an optimization control method that takes the maximum total vehicle travel distance in the congested sub-area as the optimization target; The main line dynamic section variable speed limit and multi-entry ramp linkage control method is a double-layer optimization control method that takes the maximum total driving distance of vehicles in the multi-ramp system as the upper optimization target and the maximum total driving distance of vehicles in the control sub-area as the lower optimization target. Step 5: Select the total driving distance of vehicles in the relevant area within the control period as an evaluation index to evaluate the control effect of the above-mentioned optimization control method; Step 6: Solve the optimization objective function of the optimization control method matching different congestion scenarios in step 4 to obtain the optimal control sequence within the control period, specifically the entrance ramp adjustment amount and the speed limit value of the main line variable speed limit area; Step 7: Send the first element in the optimal control sequence to the system to implement linkage control of the variable speed limit in the dynamic section of the main line and the single / multiple entrance ramps; repeat the above steps at the next control moment.

2. A method for coordinated control of variable speed limit and entrance ramp on a main line of a highway according to claim 1, characterized in that: The METANET prediction model formula includes: q i (k)=ρ i (k)v i (k)λ i ; Among them, ρ i (k+1) and ρ i (k) are the densities of section i in the k+1th control cycle and the kth control cycle, Δt is the statistical time interval, L i is the length of road section i, λ i is the number of lanes in road section i, q i-1 (k) and q i (k) are the flow rates of section i-1 and section i in the kth control cycle, r i (k) is the entrance ramp adjustment value of the kth control cycle, s i (k) is the outflow of the exit ramp in the kth control cycle, v free,i is the free flow velocity, v i (k) is the speed of section i in the kth control cycle, α m is the fitting coefficient, ρ c,i is the critical density of section i; V(ρ i (k)) is the expected speed of road section i under the current density, v vsl,i (k) is the variable speed limit value of section i in the kth control cycle, which is obtained by solving the optimization model; T is the control step size; τ is the driver's response time to traffic density perception; η is the expected parameter; κ is the elasticity coefficient.

3. A method for coordinated control of variable speed limit and entrance ramp on main line of expressway according to claim 1, characterized in that: The method for obtaining the congestion propagation length in step 2 specifically includes: When the average speed of vehicles in a sub-section within a certain control cycle is less than the set congestion threshold, the sub-section is determined to be congested and marked, and vice versa; After completing the congestion status marking of all sub-road sections, the congestion propagation length that meets the congestion propagation rule within the control period is statistically calculated.

4. A method for coordinated control of variable speed limit and entrance ramp on main line of expressway according to claim 3, characterized in that: The congestion propagation rules include: The congested area needs to satisfy spatiotemporal continuity; The congestion propagation direction is upstream; The congestion area boundaries need to be continuous.

5. The method for coordinated control of variable speed limit and entrance ramp on main line of expressway according to claim 1, characterized in that: Determine the variable speed limit area A on the main line in step 3 vsl The methods include: Assume that the congestion propagation length in the kth control period is L jam (k), the congestion sub-area is numbered as p, the upstream control sub-area of ​​the congestion sub-area is p-1, and the connection length between the congestion sub-area and the upstream control sub-area is L r , the buffer area in each control sub-area is A b , the buffer length is L b ; Fixed speed limit zone is A f , the length of the fixed speed limit area is L f ; The kth sub-area in the main line dynamic variable speed limit section is A d,k , the length of a single main line dynamically variable speed limit sub-area is L d The number of the dynamic variable speed limit sub-area in the center of the main line dynamic variable speed limit section is n d ; then the main line variable speed limit area A vsl The formula is expressed as: in, is the fixed speed limit area of ​​the pth control sub-area, is the jth main line dynamically variable speed limit sub-area of ​​the pth control sub-area, is the fixed speed limit area of ​​the p-1th control sub-area, is the jth main line dynamic variable speed limit sub-area of ​​the p-1th control sub-area; p is a positive integer; When p is 1, it means that congestion is propagating in a single control sub-area. At this time:

6. A method for coordinated control of variable speed limit and entrance ramp on a main line of a highway according to claim 5, characterized in that: When p=1, the main line dynamic section variable speed limit and single entrance ramp linkage control method are selected; when p>1, the main line dynamic section variable speed limit and multiple entrance ramp linkage control method are selected.

7. A method for coordinated control of variable speed limit and entrance ramp on main line of expressway according to claim 5, characterized in that: The main line dynamic section variable speed limit and single entrance ramp linkage control method specifically includes: Set the optimization goal: select the maximum total driving distance of vehicles in the congested sub-area p as the optimization goal; Set up constraints: (1) When A vsl =[A f ] p When , the main line speed limit area of ​​the congested sub-area is a fixed speed limit area: The speed limit value of the congested sub-area p in the fixed speed limit area of ​​the main line of a certain control period should be within the set threshold, that is, the variable speed limit value constraint of the fixed speed limit area; The speed limit difference of the congested sub-area p in the main line fixed speed limit area of ​​two adjacent control periods should be within the set threshold, that is, the speed limit difference constraint of adjacent control periods; The upstream traffic volume of the main line should be less than the dynamic capacity of the bottleneck location; (2) When A vsl =[A f ,A d,j ] p When the speed limit area of ​​the main line in the congested sub-area is fixed and dynamic speed limit areas: The variable speed limit value constraint is met in both the fixed speed limit area and the dynamic speed limit area; The speed limit difference constraint of adjacent control cycles is satisfied in both the fixed speed limit area and the dynamic speed limit area; The safe collision time is not less than the safe collision time threshold, that is, the speed limit value constraint of the adjacent variable speed limit area; the safe collision time is the ratio of the longitudinal distance of the leading vehicle in the adjacent dynamic variable speed limit sub-area in the dynamic speed limit area to the speed limit difference of the adjacent dynamic variable speed limit sub-area; Satisfy the entrance ramp signal control constraints of the congested sub-area, including cycle time constraints, green light time constraints and entrance ramp queue length constraints.

8. The method for coordinated control of variable speed limit and entrance ramp on main line of expressway according to claim 5, characterized in that: The main line dynamic section variable speed limit and multi-entry ramp linkage control method specifically includes: Set optimization goals: Upper-level optimization goal: The total distance traveled by vehicles in a multi-ramp system is maximized; Lower-level optimization goal: maximize the total driving distance of vehicles in the control sub-area; Set up constraints: Upper constraint: The upstream outflow of the main line is less than the dynamic capacity of the bottleneck position of the congested sub-area; Lower constraint: (1) When A vsl ={[A f ,A d,{1,2,...,n]} ] p ,[A f ,A d,{1,2,...,n]} ] p-1 ...[A f ] 1 }, the main line speed limit area of ​​the congested sub-area is a fixed speed limit area and a dynamic speed limit area, and the main line speed limit area of ​​the congested upstream sub-area is a fixed speed limit area: The congested sub-area satisfies the variable speed limit value constraint, the speed limit difference constraint of adjacent control cycles, and the speed limit value constraint of adjacent variable speed limit areas in the fixed speed limit area and the dynamic speed limit area; the congested upstream sub-area satisfies the variable speed limit value constraint and the speed limit difference constraint of adjacent control cycles in the fixed speed limit area; (2) When A vsl ={[A f ,A d,{1,2,...,n]} ] p ,[A f ,A d,{1,2,...,n]} ] p-1 ...[A f ,A d,j ] 1 }, the mainline speed limit areas in the congested sub-area and the congested upstream sub-area are both fixed speed limit areas and dynamic speed limit areas: The fixed speed limit area and dynamic speed limit area in the congested sub-area and the congested upstream sub-area all meet the variable speed limit value constraints of the speed limit area, the speed limit difference constraints of adjacent control cycles, and the speed limit value constraints of adjacent variable speed limit areas.

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