A dynamic lighting system and method for highway intersections considering traffic flow

Abstract

A dynamic lighting system and method for highway intersections that consider traffic flow, which belongs to the technical field of public place lighting. The present invention solves the problem that the existing dynamic road lighting scheme does not consider the impact of traffic flow on the intersecting roads at the intersection on the accident rate at night, and the poor generalizability of the lighting device. The present invention calculates the dynamic lighting scheme for the highway intersection under different traffic flow conditions by considering the traffic flow of the intersecting roads at the intersection. This can not only significantly improve the energy-saving effect of the highway intersection lighting system, but also reduce the nighttime traffic accident rate at the highway intersection, thereby improving the safety of highway nighttime driving. At the same time, the lighting system of the present invention has low cost and low energy consumption, so the lighting system has stronger generalizability. The present invention can be applied to the technical field of public place lighting.

Description

Technical Field

[0001] The present invention belongs to the technical field of public place lighting, and in particular relates to a dynamic lighting system and method for a highway intersection taking traffic flow into consideration. Background Art

[0002] In recent years, dynamic road lighting technology has become increasingly mature and has gradually been applied to urban road lighting and highway tunnel lighting. The dynamic road lighting system can adaptively adjust the lighting level according to the state of road traffic flow, which significantly improves the intelligence level and energy saving effect. However, the current research on dynamic road lighting solutions at home and abroad still has the following problems, making it difficult to promote and apply it at highway intersections.

[0003] On the one hand, the existing dynamic road lighting scheme only considers the impact of traffic flow status in tunnels or straight sections. At highway intersections, traffic flows in different directions will generate a large number of traffic conflict points in the intersection area. In this case, it is necessary to simultaneously consider the impact of traffic flow status of different types of road users on the intersecting roads on traffic safety, and design lighting schemes based on the traffic flow status of the intersecting roads to ensure nighttime driving safety at the intersection.

[0004] On the other hand, due to the stacking of multiple intelligent terminal hardware, the energy consumption of lighting equipment is relatively high, requiring a reliable and stable power supply, and low-level road intersections usually lack power supply facilities, making the installation and maintenance of dynamic lighting systems very difficult. In addition, due to the lack of corresponding lighting solutions based on application scenarios, the lighting system costs are extremely high, but the application effect is poor, and remote areas cannot afford the economic and operating costs required to install dynamic lighting systems.

[0005] In summary, the existing dynamic road lighting scheme does not consider the impact of traffic flow on the intersecting roads at intersections on the night accident rate, and the lighting device is extremely costly and energy-intensive, resulting in poor generalizability of the lighting device. Therefore, establishing a dynamic lighting scheme for highway intersections that takes traffic flow into consideration is of great significance for improving the safety of nighttime driving at highway intersections and increasing the feasibility of promoting lighting devices at highway intersections. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the existing dynamic road lighting scheme does not consider the impact of traffic flow on the intersection road on the night accident rate, and the lighting device has poor generalizability, and proposes a dynamic lighting system and method for highway intersections that takes traffic flow into consideration.

[0007] The technical solution adopted by the present invention to solve the above technical problems is:

[0008] According to one aspect of the present invention, a dynamic lighting system for a highway intersection taking traffic flow into consideration is provided, the system comprising a lamp bracket respectively arranged at each entrance lane of the highway intersection;

[0009] Each lamp bracket includes two columns and a crossbeam. The two columns are symmetrically fixed on the ground on both sides of the entrance lane, and the other ends of the two columns jointly support the crossbeam.

[0010] The crossbeam of the lamp bracket is provided with a lighting lamp, a camera, a solar cell module and a control unit;

[0011] The solar cell module is used to convert solar energy into electrical energy and to supply power to lighting fixtures, cameras and control units;

[0012] The signal output end of the camera is connected to the signal input end of the control unit, and the signal output end of the control unit is connected to the signal input end of the lighting fixture.

[0013] Furthermore, the lighting fixture is located in the middle of the beam.

[0014] Furthermore, the lamp brackets of adjacent entrance lanes in the highway intersection share a common column.

[0015] According to another aspect of the present invention, a method for dynamic lighting of a highway intersection taking traffic flow into consideration is provided, the method specifically comprising the following steps:

[0016] Step 1: The number of entrance lanes at the highway intersection is recorded as N. A vehicle detection line perpendicular to the vehicle travel direction is set on each entrance lane, and the vertical distance between the vehicle detection line and the geometric center point of the highway intersection is L meters. The number of entrance lanes i is initialized to 1;

[0017] Step 2: Use the camera to collect video data of vehicles passing through the i-th import lane. The camera transmits the collected video data to the control unit, which then uses image processing technology to identify and track all vehicles within the vehicle detection line. The speed of each vehicle within the vehicle detection line is calculated based on the identification and tracking results. The speed of the j-th vehicle within the vehicle detection line of the i-th import lane is recorded as v ij ;

[0018] Step 3: Select the maximum speed V from the speeds of all vehicles in the vehicle detection line of the i-th import lane i =max(v ij ), and the selected speed is used as the speed of the i-th import lane;

[0019] Step 4: The import lane at the highway intersection that has a traffic conflict point with the traffic flow of the i-th import lane is regarded as the conflicting import lane of the i-th import lane, and the total number of conflicting import lanes corresponding to the i-th import lane is recorded as M;

[0020] And initialize the number of conflicting import lanes k = 1;

[0021] Step 5: Calculate the traffic conflict probability P1 between the traffic flow of the kth conflicting import lane and the ith import lane ik ;

[0022] Step 6: Calculate the probability P2 of a collision between a vehicle in the i-th import lane and the traffic flow in the k-th conflicting import lane. ik ;

[0023] Step 7: Determine whether k=M is ​​satisfied;

[0024] If not satisfied, set k=k+1 and return to step 5;

[0025] If satisfied, proceed to step eight;

[0026] Step 8: According to and Calculate the optimal illumination of the i-th import lane k=1,2,…,M;

[0027] Step 9: Determine whether i=N is satisfied;

[0028] If not satisfied, set i=i+1 and return to step 2;

[0029] If satisfied, proceed to step 10;

[0030] Step 10: According to i=1,2,…,N Calculate the optimal illumination E of the highway intersection m The control unit then calculates the optimal illumination E m A digital signal is generated and sent to the lighting fixture, and the lighting fixture adjusts the lighting brightness according to the received digital signal.

[0031] Furthermore, the traffic conflict probability P1 ik for:

[0032]

[0033] Where, t c is the average minimum headway time of vehicles on the i-th import lane when crossing the traffic flow of the k-th conflicting import lane; d k is the distance between the road stop line in the kth conflicting import lane and the conflict point; d iis the distance between the road stop line and the conflict point in the i-th import lane; V k is the speed of the kth conflicting import lane; is the headway time of the traffic flow in the i-th import lane; is the headway time of the traffic flow in the k-th conflicting import lane; for The probability density function of for The probability density function of .

[0034] Furthermore, the probability of collision for:

[0035]

[0036] Where X is the driver's visual distance of surrounding moving objects at night; E is the illumination of the highway intersection lighting system; D is the critical distance between the center of mass of the vehicle and the conflict point after the vehicle is fully braked; S is the safe braking distance of the vehicle on the i-th import lane.

[0037] Furthermore, the safe braking distance S is:

[0038]

[0039] Where, t1 is the brake free travel time; t2 is the braking deceleration linear growth time; a b is the safe braking deceleration.

[0040] Furthermore, the specific process of step eight is as follows:

[0041] Step 81: According to P1 ik and Calculation Satisfaction The minimum illumination E of the i-th import lane ik , P acp is the maximum allowable accident rate;

[0042] Step 82: E ik The minimum illumination E specified in the lighting standard min Make a comparison;

[0043] If E ik >E min , then the minimum illumination E ik constant;

[0044] If E ik ≤E min , let the minimum illumination E ik =E min ;

[0045] Similarly, the minimum illumination of the i-th import lane for each conflicting import lane is obtained respectively;

[0046] Step 83. According to E ik , k=1,2,…,M calculate the optimal illumination

[0047] Furthermore, the specific process of step eighty-three is as follows:

[0048]

[0049] Furthermore, according to i=1,2,…,N Calculate the optimal illumination E of the highway intersection m , specifically:

[0050]

[0051] The beneficial effects of the present invention are:

[0052] The present invention proposes a dynamic lighting system and method for highway intersections taking traffic flow into consideration. In the absence of historical accident data, the system and method can calculate dynamic lighting plans for highway intersections under different traffic flow conditions, providing theoretical support for formulating lighting management strategies for different time periods and regions. This can not only significantly improve the energy-saving effect of the highway intersection lighting system, but also reduce the nighttime traffic accident rate at highway intersections by considering the traffic flow of intersecting roads at the intersection, thereby improving the safety of highway nighttime driving.

[0053] At the same time, the lighting system of the present invention has low cost and low energy consumption, so the lighting system has strong generalization. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a structural schematic diagram of a dynamic lighting system for a highway intersection taking traffic flow into consideration according to the present invention;

[0055] Figure 2 It is a framework diagram of the coordinated operation of various parts in a dynamic lighting system for a highway intersection taking traffic flow into consideration according to the present invention;

[0056] Figure 3 The present invention is a flow chart of a method for dynamic lighting of a highway intersection taking traffic flow into consideration. DETAILED DESCRIPTION

[0057] Specific implementation method 1: Combination Figure 1 and Figure 2 This embodiment is described as follows. A dynamic lighting system for a highway intersection taking traffic flow into consideration is described in this embodiment. The system comprises a lamp bracket 2 respectively arranged at each entrance lane of the highway intersection;

[0058] Each lamp bracket 2 includes two upright posts and a crossbeam, the two upright posts are symmetrically fixed on the ground on both sides of the entrance lane, and the other ends of the two upright posts jointly support the crossbeam;

[0059] The crossbeam of the lamp bracket 2 is provided with a lighting lamp 1, a camera 3, a solar cell module 4 and a control unit 5;

[0060] The solar cell module 4 is used to convert solar energy into electrical energy and to supply power to the lighting fixture 1, the camera 3 and the control unit 5;

[0061] Furthermore, the signal output end of the camera 3 is connected to the signal input end of the control unit 5 , and the signal output end of the control unit 5 is connected to the signal input end of the lighting fixture 1 .

[0062] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that the lighting fixture 1 is located in the middle of the beam.

[0063] The other steps and parameters are the same as those in the first embodiment.

[0064] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that the lamp brackets 2 of adjacent import lanes in the highway intersection share a common column.

[0065] The other steps and parameters are the same as those in the first or second embodiment.

[0066] For example, for a cross intersection, the north import lane and the west import lane are adjacent import lanes, the west import lane and the south import lane are adjacent import lanes, the south import lane and the east import lane are adjacent import lanes, and the north import lane and the east import lane are adjacent import lanes.

[0067] Specific implementation method four: Combination Figure 3 The present embodiment describes a method for dynamic lighting of a highway intersection taking traffic flow into consideration, and the method specifically comprises the following steps:

[0068] Step 1: The number of entrance lanes of the highway intersection is recorded as N, and a vehicle detection line perpendicular to the vehicle travel direction is set on each entrance lane, and the vertical distance between the vehicle detection line and the geometric center point of the highway intersection is L meters (L is taken as 100 in the present invention), and the number of entrance lanes i=1 is initialized;

[0069] Step 2: Use camera 3 to collect video data of vehicles passing on the i-th import lane. Camera 3 transmits the collected video data to control unit 5. Control unit 5 then uses image processing technology to identify and track all vehicles within the vehicle detection line (i.e., between the vehicle detection line and the intersection), calculates the speed of each vehicle within the vehicle detection line based on the identification and tracking results, and records the speed of the j-th vehicle within the vehicle detection line of the i-th import lane as v ij ;

[0070] Step 3: Select the maximum speed V from the speeds of all vehicles in the vehicle detection line of the i-th import lane i =max(v ij ), and the selected speed is used as the speed of the i-th import lane;

[0071] Step 4: The import lane at the highway intersection that has a traffic conflict point with the traffic flow of the i-th import lane is regarded as the conflicting import lane of the i-th import lane, and the total number of conflicting import lanes corresponding to the i-th import lane is recorded as M;

[0072] And initialize the number of conflicting import lanes k = 1;

[0073] Step 5: Calculate the traffic conflict probability P1 between the traffic flow of the kth conflicting import lane and the ith import lane ik ;

[0074] Step 6: Calculate the probability of a collision between a vehicle in the i-th import lane and the traffic flow in the k-th conflicting import lane.

[0075] Step 7: Determine whether k=M is ​​satisfied;

[0076] If not satisfied, set k=k+1 and return to step 5;

[0077] If satisfied, proceed to step eight;

[0078] Step 8: According to P1 ik and Calculate the optimal illumination of the i-th import lane k=1,2,…,M;

[0079] Step 9: Determine whether i=N is satisfied;

[0080] If not satisfied, set i=i+1 and return to step 2;

[0081] If satisfied, proceed to step 10;

[0082] Step 10: According to i=1,2,…,N Calculate the optimal illumination E of the highway intersectionm The control unit 5 then calculates the optimal illumination E m A digital signal is generated and sent to the lighting fixture 1, and the lighting fixture 1 adjusts the lighting brightness according to the received digital signal.

[0083] The method of the present invention can dynamically adjust the lighting brightness according to the vehicle situation between the vehicle detection line and the highway intersection.

[0084] Specific implementation method 5: This implementation method is different from the specific implementation method 4 in that the traffic conflict probability P1 ik for:

[0085]

[0086] In the formula, t c is the average minimum headway time of vehicles on the i-th import lane when crossing the traffic flow of the k-th conflicting import lane (here, it is the average minimum headway time acceptable to drivers, which is taken as 7s in the present invention); d k is the distance between the road stop line in the kth conflicting import lane and the conflict point; d i is the distance between the road stop line and the conflict point in the i-th import lane; d i and d k It can be obtained by measuring the above position of the intersection; V k is the speed of the kth conflicting import lane; is the headway time of the traffic flow in the i-th import lane; is the headway time of the traffic flow in the k-th conflicting import lane; for The probability density function of for The probability density function of .

[0087] The other steps and parameters are the same as those in the fourth embodiment.

[0088] and The headway between the i-th import lane and the k-th conflicting import lane in different time periods can be calculated. and Traffic surveys are conducted and kernel density estimation is used to obtain the probability of traffic conflicts between traffic flows from different entrance lanes in the highway intersection area, thereby providing input parameters for solving the optimal dynamic lighting scheme for highway intersections under different traffic flow conditions to obtain the optimal dynamic lighting scheme.

[0089] Specific implementation method 6: This implementation method is different from specific implementation methods 4 or 5 in that the probability of collision for:

[0090]

[0091] Wherein, X is the driver's visual distance of surrounding moving objects at night; E is the illumination of the highway intersection lighting system; D is the critical distance between the center of mass of the vehicle and the conflict point after the vehicle is fully braked (taken as 5 meters in the present invention); S is the safe braking distance of the vehicle on the i-th import lane.

[0092] The other steps and parameters are the same as those in the fourth or fifth embodiment.

[0093] Specific implementation method 7: This implementation method is different from any one of specific implementation methods 4 to 6 in that the safety braking distance S is:

[0094]

[0095] Wherein, t1 is the brake free travel time (taken as 0.03s in the present invention); t2 is the braking deceleration linear growth time (taken as 0.3s in the present invention); a b is the safe braking deceleration (taken as 4.5m / s in the present invention) 2 ).

[0096] The other steps and parameters are the same as those in Specific Implementation Methods 4 to 6.

[0097] This implementation can accurately calculate the safe braking distance of the vehicle, and further provide input parameters for solving the optimal dynamic lighting solution for the highway intersection under different traffic flow conditions, so as to obtain the optimal dynamic lighting solution.

[0098] Specific implementation eight: This implementation is different from any one of specific implementations four to seven in that the specific process of step eight is as follows:

[0099] Step 81: According to P1 ik and Calculation Satisfaction The minimum illumination E of the i-th import lane ik , P acp is the maximum allowable accident rate; in the present invention, P acp The value of is 0.99;

[0100] Step 82: E ik The minimum illumination E specified in the lighting standard min For comparison (E min The value of is 20lx);

[0101] If E ik >E min , then the minimum illumination E ik constant;

[0102] If E ik ≤E min , let the minimum illumination E ik =E min ;

[0103]

[0104] Similarly, the minimum illumination of the i-th import lane for each conflicting import lane is obtained respectively;

[0105] Step 83. According to E ik , k=1,2,…,M calculate the optimal illumination

[0106] The other steps and parameters are the same as those in Specific Implementation Methods 4 to 7.

[0107] This implementation can solve the optimal dynamic lighting solution for highway intersections under different traffic flow conditions.

[0108] Specific implementation method 9: This implementation method is different from specific implementation methods 4 to 8 in that the specific process of step 83 is as follows:

[0109]

[0110] That is, the maximum illumination is selected as the optimal illumination from the minimum illumination for each conflicting import lane.

[0111] The other steps and parameters are the same as those in Specific Implementation Methods 4 to 8.

[0112] Specific implementation method 10: This implementation method is different from the specific implementation methods 4 to 9 in that the i=1,2,…,N Calculate the optimal illumination E of the highway intersection m , specifically:

[0113]

[0114] That is, the maximum value is selected from the optimal illumination of all import lanes, and the selected maximum value is used as the optimal illumination of the highway intersection.

[0115] The other steps and parameters are the same as those in Specific Implementation Methods 4 to 9.

[0116] Experimental Section

[0117] A cross-shaped highway intersection with a lighting period from 19:00 to 6:00 the next day was selected to verify the effect of a dynamic lighting system and method for a highway intersection that takes traffic flow into consideration proposed by the present invention. The headway time of the traffic flow in each entrance lane of the highway intersection conforms to the log-normal distribution. In the original lighting scheme, the illumination of the lighting device is automatically increased to 36lx when the vehicle arrives at the intersection. The lighting time is divided into three periods: 19:00-21:00, 21:00-23:00 and 23:00-6:00 (next day). The input vehicle speed V of the lighting device in the three periods is within the range of 30km / h-70km / h, and the optimal illumination E of the highway intersection lighting device proposed by the present invention is calculated. m As shown in Table 1.

[0118] Table 1 E at different input vehicle speeds in three time periods m

[0119]

[0120] According to the illumination value of the original scheme and the optimal illumination value in Table 1, the energy saving rate ESR of the lighting system under different time periods and input vehicle speeds is calculated as shown in Table 2. According to the data in Table 2, the average energy saving rate AESR corresponding to the three time periods within the range of 30km / h-70km / h and the daily average energy saving rate DAESR ​​of the lighting system are calculated respectively, where DAESR ​​is the weighted average of the AESR of all time periods of the day, and the weight is the ratio of the lighting time in each time period to the total lighting time of the whole day. The calculation results show that the AESR of the optimized lighting scheme in the three time periods is 35.38%, 35.57% and 36.97% respectively, and the DAESR ​​is 36.43%. The above indicators show that the dynamic lighting system and method for highway intersections considering traffic flow proposed by the present invention can effectively reduce the power consumption of the highway intersection lighting system.

[0121] Table 2 ESR at different vehicle speeds in three time periods

[0122]

[0123] The above calculation examples of the present invention are only used to explain the calculation model and calculation process of the present invention in detail, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A dynamic lighting method based on a dynamic lighting system for a highway intersection taking traffic flow into consideration, the system comprising a lamp bracket (2) respectively arranged at each entrance lane of the highway intersection; each lamp bracket (2) comprises two columns and a crossbeam, the two columns are symmetrically fixed on the ground at both sides of the entrance lane, and the other ends of the two columns jointly support the crossbeam; a lighting fixture (1), a camera (3), a solar cell module (4) and a control unit (5) are arranged on the crossbeam of the lamp bracket (2); the solar cell module (4) is used to convert solar energy into electrical energy and to supply power to the lighting fixture (1), the camera (3) and the control unit (5); and the signal output end of the camera (3) is connected to the signal input end of the control unit (5), and the signal output end of the control unit (5) is connected to the signal input end of the lighting fixture (1); the lighting fixture (1) is located in the middle of the crossbeam; the lamp brackets (2) of adjacent entrance lanes in the highway intersection share a common column; it is characterized in that The method specifically comprises the following steps: Step 1: The number of entrance lanes at the highway intersection is recorded as N. A vehicle detection line perpendicular to the vehicle travel direction is set on each entrance lane, and the vertical distance between the vehicle detection line and the geometric center point of the highway intersection is L meters. The number of entrance lanes i is initialized to 1; Step 2: Use the camera (3) to collect video data of vehicles passing through the i-th import lane. The camera (3) transmits the collected video data to the control unit (5). The control unit (5) then uses image processing technology to identify and track all vehicles within the vehicle detection line, calculates the speed of each vehicle within the vehicle detection line based on the identification and tracking results, and records the speed of the j-th vehicle within the vehicle detection line of the i-th import lane as v ij ; Step 3: Select the maximum speed V from the speeds of all vehicles in the vehicle detection line of the i-th import lane i =max(v ij ), and the selected speed is used as the speed of the i-th import lane; Step 4: The import lane at the highway intersection that has a traffic conflict point with the traffic flow of the i-th import lane is regarded as the conflicting import lane of the i-th import lane, and the total number of conflicting import lanes corresponding to the i-th import lane is recorded as M; And initialize the number of conflicting import lanes k = 1; Step 5: Calculate the traffic conflict probability P1 between the traffic flow of the kth conflicting import lane and the ith import lane ik ; Step 6: Calculate the probability of collision between vehicles in the i-th import lane and the traffic flow in the k-th conflicting import lane. Step 7: Determine whether k=M is ​​satisfied; If not satisfied, set k=k+1 and return to step 5; If satisfied, proceed to step eight; Step 8: According to P1 ik and Calculate the optimal illumination of the i-th import lane The specific process of step eight is as follows: Step 81: According to P1 ik and Calculation Satisfaction The minimum illumination E of the i-th import lane ik , P acp is the maximum allowable accident rate; Step 82: E ik The minimum illumination E specified in the lighting standard min Make a comparison; If E ik >E min , then the minimum illumination E ik constant; If E ik ≤E min , let the minimum illumination E ik =E min ; Similarly, the minimum illumination of the i-th import lane for each conflicting import lane is obtained respectively; Step 83. According to E ik , k=1,2,…,M calculate the optimal illumination Step 9: Determine whether i=N is satisfied; If not satisfied, set i=i+1 and return to step 2; If satisfied, proceed to step 10; Step 10: According to Calculate the optimal illumination E at a highway intersection m The control unit (5) then calculates the optimal illumination E of the highway intersection. m A digital signal is generated and sent to the lighting fixture (1), and the lighting fixture (1) adjusts the lighting brightness according to the received digital signal.

2. The dynamic lighting method of a dynamic lighting system for a highway intersection considering traffic flow according to claim 1, characterized in that: The traffic conflict probability P1 ik for: Where, t c is the average minimum headway time of vehicles on the i-th import lane when crossing the traffic flow of the k-th conflicting import lane; d k is the distance between the road stop line in the kth conflicting import lane and the conflict point; d i is the distance between the road stop line and the conflict point in the i-th import lane; V k is the speed of the kth conflicting import lane; is the headway time of the traffic flow in the i-th import lane; is the headway time of the traffic flow in the k-th conflicting import lane; for The probability density function of for The probability density function of .

3. The dynamic lighting method of a highway intersection dynamic lighting system considering traffic flow according to claim 1, characterized in that: The probability of a collision for: Where X is the driver's visual distance of surrounding moving objects at night; E is the illumination of the highway intersection lighting system; D is the critical distance between the center of mass of the vehicle and the conflict point after the vehicle is fully braked; S is the safe braking distance of the vehicle on the i-th import lane.

4. The dynamic lighting method of a dynamic lighting system for a highway intersection considering traffic flow according to claim 3, characterized in that: The safe braking distance S is: Where, t1 is the brake free travel time; t2 is the braking deceleration linear growth time; a b is the safe braking deceleration.

5. The dynamic lighting method of a dynamic lighting system for a highway intersection considering traffic flow according to claim 1, characterized in that: The basis Calculate the optimal illumination E at a highway intersection m , specifically:

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