Evaluation method of nighttime visibility of road markings

Abstract

The present application discloses a method for evaluating the nighttime visibility of road markings, a method for setting road markings, and applicable roads. The method for evaluating the nighttime visibility of road markings includes: determining the safe sight distance at the specified speed based on the specified speed of the road with road markings; determining the threshold of the retroreflection coefficient of the road markings based on the safe sight distance and road marking characteristics according to a retroreflection coefficient model in which the sight distance changes with the retroreflection coefficient; obtaining the retroreflection coefficient of the road markings; and evaluating the nighttime visibility of the road markings based on the obtained retroreflection coefficient and the determined retroreflection coefficient threshold. The nighttime visibility evaluation technology for road markings provided in the embodiments of the present application can fully meet the driver's need for visual recognition of road markings for safe and comfortable driving on roads at night.

Description

Technical Field

[0001] The present application relates to the field of highway traffic, specifically to a road marking setting technology, more specifically to a marking nighttime visibility evaluation method, and also to a marking setting method and a road. Background Art

[0002] Traffic markings painted on the road are a traffic control facility that channels traffic, guides alignment, and ensures traffic safety. They can define lane boundaries, regulate and manage driving behavior, guide drivers' line of sight, indicate and warn of road conditions ahead, and clarify the use of road rights.

[0003] Traffic markings are the main guide for nighttime driving. In the specific environment of nighttime, due to low ambient brightness and limited visibility, drivers cannot clearly judge the traffic conditions on the road ahead. Especially on roads without street lighting, drivers rely heavily on markings to obtain information about the road ahead. If the markings cannot provide drivers with sufficient visibility, drivers cannot correctly confirm their driving trajectory with their own senses, which is not conducive to safe driving at night and brings safety risks to driving. In order to ensure safe driving, it is particularly important to evaluate the visibility of nighttime markings.

[0004] However, there is currently a lack of evaluation methods for the nighttime visibility of road traffic markings that can effectively meet drivers' safety visual needs.

[0005] The content of this background technology description is only for facilitating understanding of the relevant technology in this field and is not regarded as an admission of the prior art. Summary of the invention

[0006] Therefore, the embodiments of the present application hope to provide a method for evaluating the nighttime visibility of highway traffic markings based on the driver's safety vision needs, thereby achieving a marking visibility assessment based on meeting the driver's vision needs for highway traffic markings for safe driving at night, and being able to selectively further process the markings based on the assessment results.

[0007] Accordingly, the embodiments of the present application also hope to provide a marking setting method and a road, wherein the markings set by the marking setting method or the markings on the road can fully meet the driver's visual recognition needs for highway traffic markings for safe driving at night.

[0008] In a first aspect, a method for evaluating the nighttime visibility of a road marking is provided, which may include:

[0009] Based on a prescribed vehicle speed on a road with markings, determining a safe sight distance at the prescribed vehicle speed;

[0010] According to a retroreflection coefficient model in which the sight distance varies with the retroreflection coefficient, determining the retroreflection coefficient threshold of the marking based on the safe sight distance and marking characteristics, wherein the marking characteristics include marking color and / or width;

[0011] Get the retroreflection coefficient of the marking line;

[0012] The nighttime visibility of the marking is evaluated based on the acquired retroreflection coefficient and the determined retroreflection coefficient threshold.

[0013] Optionally, the retroreflection coefficient model is one or more selected from a linear function model, a quadratic function model, an exponential function model, a power function model and a logarithmic function model.

[0014] Optionally, the inverse reflection coefficient model includes a plurality of different models based on different marking line characteristics, and is shown in the following formula:

[0015] f i (x) = A i ln(x)-B i

[0016] Among them, f(x) represents the viewing distance, i refers to different models corresponding to different marking characteristics, x represents the retroreflection coefficient of the marking, and A and B are positive constants.

[0017] Optionally, the multiple models are shown in the following formula:

[0018] ① For the marking line with the first color and the first width:

[0019] f 1 (x) = 29.122ln(x) - 53.955

[0020] ②For the marking line with the first color and the second width:

[0021] f 2 (x) = 27.413ln(x) - 34.402

[0022] ③For the marking line with the second color and the first width:

[0023] f 3 (x) = 28.94ln(x) - 54.188

[0024] ④ For the marking line with the second color and the second width:

[0025] f 4 (x)=28.468ln(x)-42.526.

[0026] Optionally, the method for evaluating the nighttime visibility of a marking may further include:

[0027] The retroreflectance model is constructed.

[0028] Optionally, constructing the inverse reflection coefficient model includes:

[0029] Acquiring visual recognition data of a plurality of drivers on a marking, wherein the visual recognition data includes a plurality of different viewing distances corresponding to a plurality of different retroreflection coefficients under different marking characteristics;

[0030] The retroreflection coefficient model is generated by fitting the visual recognition data.

[0031] Optionally, obtaining visual recognition data of different types of road markings by multiple different drivers includes:

[0032] S1211: For each of the plurality of marking colors and widths, provide a plurality of test markings having a different coefficient of retroreflection;

[0033] S1213: placing one of the plurality of test markings on the road as the marking to be tested or covering the remaining test markings other than the marking to be tested;

[0034] S1214: one of the multiple drivers drives the vehicle slowly with the high beam turned on towards the line to be tested from a distance until the line to be tested appears as a horizontal line in the driver's field of vision;

[0035] S1215: Acquire the distance between the vehicle and the marking line to be measured when a horizontal line appears in the driver's field of vision as the sight distance corresponding to the retroreflection coefficient of the marking line to be measured;

[0036] S1216: for each test marking line, repeat steps S1214 to S1215 until completion;

[0037] S1217: For each driver, repeat steps S1213 to S1216 until completion.

[0038] Optionally, obtaining visual recognition data of different markings by multiple drivers may further include:

[0039] S1212: Adjusting the eye height of one of the plurality of drivers in the vehicle.

[0040] In a second aspect, a marking line setting method is provided, which may include:

[0041] Evaluating the nighttime visibility of the markings by the method for evaluating the nighttime visibility of the markings according to the embodiment of the present application;

[0042] If the nighttime visibility of the marking does not meet the predetermined requirements, the marking is redrawn.

[0043] Optionally, redrawing the marking line comprises:

[0044] Adjust the refractive index and / or particle size ratio of the reflective particles incorporated into the marking material.

[0045] In a third aspect, a road is provided, comprising a plurality of line markings, at least one of the plurality of line markings can be set according to the line marking setting method described in an embodiment of the present application.

[0046] In some embodiments of the present invention, the visibility evaluation may be to determine the visibility. The nighttime visibility evaluation method of road markings provided in the embodiments of the present application can use the driver's nighttime visibility distance of road markings as an indicator for evaluating the visibility of nighttime road markings from the perspective of the driver's need for visibility of road markings for safe and comfortable driving on roads at night, and use the retroreflection coefficient model based on different road marking characteristics to obtain the minimum value of the retroreflection coefficient of different types of road markings that meets the driver's nighttime visibility needs, thereby realizing a safe and reasonable nighttime road traffic marking visibility evaluation technology.

[0047] Optional features and other effects of the embodiments of the present invention are partially described below and partially understood by reading this document. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The elements shown are not limited to the proportions shown in the drawings and the same or similar reference numerals in the drawings represent the same or similar elements, wherein:

[0049] Figure 1 A first exemplary flow chart of a method for evaluating the nighttime visibility of a marking according to an embodiment of the present application is shown;

[0050] Figure 2 A second exemplary flow chart of a method for evaluating the nighttime visibility of a marking according to an embodiment of the present application is shown;

[0051] Figure 3 A third exemplary flow chart of a method for evaluating the nighttime visibility of a marking according to an embodiment of the present application is shown;

[0052] Figure 4 A fourth exemplary flow chart of a method for evaluating the nighttime visibility of a marking according to an embodiment of the present application is shown;

[0053] Figure 5 An exemplary flow chart of a marking line setting method according to an embodiment of the present application is shown;

[0054] Figure 6 A schematic diagram of nighttime visibility of a marking according to an embodiment of the present application is shown;

[0055] Figure 7 A schematic diagram of a test section plane according to an embodiment of the present application is shown;

[0056] Figure 8 A sample schematic diagram showing how the driver's visual distance for a white line marking changes with the change of the retroreflection coefficient according to an embodiment of the present application;

[0057] Fig. 9 A sample schematic diagram showing how the driver's visual distance for a yellow line marking changes with the change of the retroreflection coefficient according to an embodiment of the present application;

[0058] Fig.10 A fitting curve diagram of the retroreflection coefficient and the visual recognition distance of a white marking line according to an embodiment of the present application is shown;

[0059] Fig.11 A fitting curve diagram of the retroreflection coefficient and the visual recognition distance of the yellow marking line according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific implementation methods and drawings. Here, the exemplary implementation methods of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0061] The term "including" and its variations used in this document represent open inclusion, that is, "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one other embodiment". In order to facilitate the understanding of this specification, the sequential terms "first", "second", etc. are used in this document to distinguish different elements / items / objects, and do not indicate the order or importance of different elements / items / objects. In particular, the method steps represented by the terms "first", "second", etc. are not used to indicate the order of method execution; when an embodiment contains elements / items / objects represented in a later order, the elements / items / objects represented by the terms "first", "second", etc. in the previous order are not necessarily essential technical features of the embodiment.

[0062] As mentioned above, there is currently a lack of evaluation methods for the nighttime visibility of road traffic markings that can effectively meet the safety visual needs of drivers.

[0063] Accordingly, the embodiments of the present application hope to provide a method for evaluating the nighttime visibility of highway traffic markings based on the driver's safety vision needs, thereby achieving a marking visibility assessment based on meeting the driver's vision needs for highway traffic markings for safe driving at night, and being able to selectively perform further processing on the markings based on the assessment results.

[0064] Furthermore, the embodiments of the present application also hope to provide a marking setting method and a road, wherein the markings set by the marking setting method or the markings on the road can fully meet the driver's visual recognition needs for highway traffic markings for safe driving at night.

[0065] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Figure 1 A method for evaluating the visibility of a marking at night is shown, which may include:

[0066] S110: determining a safe sight distance at a prescribed vehicle speed on a road with markings based on the prescribed vehicle speed;

[0067] In the embodiments of the present application, the prescribed speed is interpreted broadly. In one embodiment, the prescribed speed is the speed limit of the road or, when there are multiple speed limits, one of the speed limits, such as the speed limit of most of the road. In one embodiment, the prescribed speed is the speed set by a person skilled in the art according to the teachings of the present invention when implementing the embodiments of the present invention, such as a speed set based on the speed limit and after considering a safety factor; or, an average of multiple speed limits. In the embodiments of the present invention, the "prescribed speed of the road" can be, for example, the aforementioned speed limit, one of the speed limits, a set speed with a safety factor, or an average speed.

[0068] In the embodiment of the present application, the viewing distance may also be referred to as the visual distance or the visible distance.

[0069] In one embodiment of the present application, determining the safe sight distance at the prescribed vehicle speed includes: determining the safe sight distance based on the prescribed vehicle speed and a given visual recognition reaction time (also referred to as a safety preview time).

[0070] In one embodiment, the safe sight distance may conform to the following formula:

[0071] D s =V d *T s

[0072] Where D s is the safe sight distance, V d is the specified vehicle speed, T s Preview time for safety.

[0073] S130: determining a threshold value of the retroreflection coefficient of the marking line based on the safety sight distance and the marking line characteristics according to a retroreflection coefficient model in which the sight distance changes with the retroreflection coefficient;

[0074] In one embodiment, the marking characteristics may include marking color and / or width. Preferably, the marking characteristics may include marking color and width. For example, marking color may include white and yellow; marking width may include 15 cm and 20 cm, but other colors and / or widths are contemplated.

[0075] In a further embodiment, the retroreflection coefficient model is one or more selected from a linear function model, a quadratic function model, an exponential function model, a power function model and a logarithmic function model.

[0076] In a further embodiment, the retroreflection coefficient model includes a plurality of different models based on different marking line features. For example, there may be a corresponding model for each different marking line feature, such as each different color and each different width.

[0077] In a further embodiment, the inverse reflection coefficient model may be expressed as follows:

[0078] f i (x) = A i ln(x)-B i

[0079] Among them, f(x) represents the viewing distance, i refers to different models corresponding to different marking characteristics, x represents the retroreflection coefficient of the marking, and A and B are positive constants.

[0080] In a further embodiment, the multiple models are shown as follows:

[0081] ① For the marking line with the first color and the first width:

[0082] f 1 (x) = 29.122ln(x) - 53.955

[0083] ②For the marking line with the first color and the second width:

[0084] f 2 (x) = 27.413ln(x) - 34.402

[0085] ③For the marking line with the second color and the first width:

[0086] f 3 (x) = 28.94ln(x) - 54.188

[0087] ④ For the marking line with the second color and the second width:

[0088] f 4 (x)=28.468ln(x)-42.526.

[0089] In some embodiments, the first color may be white, and the second color may be yellow; the first width may be 15 cm, and the second width may be 20 cm.

[0090] S140: Obtaining the retroreflection coefficient of the marking line;

[0091] In some embodiments, in step S140, for example, a retroreflection measurement tool may be used to measure and determine the retroreflection coefficient of the test reticle.

[0092] S150: Evaluate the nighttime visibility of the marking based on the acquired retroreflection coefficient and the determined retroreflection coefficient threshold.

[0093] In some embodiments, it may be determined that the nighttime visibility of the marking does not meet the requirement based on the obtained retroreflection coefficient being less than the determined retroreflection coefficient threshold.

[0094] In such Figure 2 In the embodiment shown, the method for evaluating the visibility of a marking at night may further include step S120. Figure 2 As shown, the method may include:

[0095] S110: determining a safe sight distance at a prescribed vehicle speed on a road with markings based on the prescribed vehicle speed;

[0096] S120: constructing the retroreflection coefficient model;

[0097] S130: determining a threshold value of the retroreflection coefficient of the marking line based on the safety sight distance and the marking line characteristics according to a retroreflection coefficient model in which the sight distance changes with the retroreflection coefficient;

[0098] S140: Obtaining the retroreflection coefficient of the marking line;

[0099] S150: Evaluate the nighttime visibility of the marking based on the acquired retroreflection coefficient and the determined retroreflection coefficient threshold.

[0100] like Figure 3 In the illustrated embodiment, step S120 may specifically include:

[0101] S121: Acquiring visual recognition data of a plurality of drivers on the markings, wherein the visual recognition data includes a plurality of different viewing distances corresponding to a plurality of different retroreflection coefficients under different marking features;

[0102] S122: Generate the retroreflection coefficient model by fitting the visual recognition data.

[0103] In such Figure 4 In the illustrated embodiment, step S121 may specifically include:

[0104] S1211: For each of the plurality of marking colors and widths, provide a plurality of test markings having a different coefficient of retroreflection;

[0105] In some embodiments, test markings with different retroreflection coefficients can be obtained by scattering glass beads with different refractive indices or different particle size ratios.

[0106] In some embodiments, the retroreflection coefficient of the test mark line may be obtained in a manner similar to the retroreflection coefficient acquisition method described in step S140 or in other known manners of acquiring the retroreflection coefficient.

[0107] S1213: placing one of the plurality of test markings on the road as the marking to be tested or covering the remaining test markings other than the marking to be tested;

[0108] In one embodiment, a plurality of test marks may be provided as separate components, as described in other specific embodiments herein. Here, corresponding test marks (components) may be placed at specified positions in step S1213.

[0109] In another embodiment, a plurality of test markings may be drawn on a road surface (a normal road or a test road). Here, the remaining test markings other than the markings to be tested may be covered in step S1213.

[0110] S1214: one of the multiple drivers drives the vehicle slowly with the high beam turned on towards the line to be tested from a distance until the line to be tested appears as a horizontal line in the driver's field of vision;

[0111] In one embodiment, slow speed refers to a vehicle speed of 0-10 km / h.

[0112] In a preferred embodiment, one of the multiple drivers drives the vehicle with the high beam on at a slow speed towards the marking line to be tested from a distance until the marking line to be tested appears as a horizontal line in the driver's field of vision, including:

[0113] The driver drives the vehicle slowly towards the marking line to be tested and stops the vehicle when a horizontal line appears in the field of vision.

[0114] like Figure 7 As shown, the driving direction and the marking direction are set as in normal driving, so that the vehicle drives toward the marking from a distance along the marking direction.

[0115] S1215: Acquire the distance between the vehicle and the marking line to be measured when a horizontal line appears in the driver's field of vision as the sight distance corresponding to the retroreflection coefficient of the marking line to be measured;

[0116] S1216: for each test marking line, repeat steps S1214 to S1215 until completion;

[0117] S1217: For each driver, repeat steps S1213 to S1216 until completion.

[0118] exist Figure 4 In the illustrated embodiment, the previous steps may be repeated for each test line, but it is conceivable that as an equivalent, the previous steps may be repeated for each driver. In other words, the aforementioned steps S1216 and S1217 may have different sequences.

[0119] As an optional embodiment, Figure 4 As shown, step S121 may further include: S1212: adjusting the height of one of the plurality of drivers in the vehicle. Here, in a further embodiment, the above step S1217 may repeat steps S1212 to S1216 for each driver until the end.

[0120] In the embodiments of the present application, Figure 5 As shown, a marking line setting method may also be provided, which may include:

[0121] S510: Evaluate the nighttime visibility of the markings by using the nighttime visibility evaluation method of the markings;

[0122] S520: If the nighttime visibility of the line marking does not meet the predetermined requirement, redraw the line marking.

[0123] In an embodiment of the present application, the method for evaluating the nighttime visibility of a road marking is the method for evaluating the nighttime visibility of a road marking according to an embodiment of the present application.

[0124] Optionally, re-marking the marking line may include:

[0125] Adjust the refractive index and / or particle size ratio of the reflective particles incorporated into the marking material.

[0126] In an embodiment of the present application, a road may be provided, comprising a plurality of line markings, at least one of the plurality of line markings, and preferably all of the line markings may be set by the line marking setting method according to the embodiment of the present application.

[0127] In an embodiment of the present invention, a device for evaluating the nighttime visibility of a road marking is also provided, which may include: a sight distance determination unit, configured to determine a safe sight distance at a prescribed vehicle speed based on a prescribed vehicle speed on a road with road markings; a retroreflection coefficient threshold determination unit, configured to determine a retroreflection coefficient threshold of the road marking based on the safe sight distance and road marking characteristics according to a retroreflection coefficient model in which the sight distance changes with the retroreflection coefficient; a retroreflection coefficient acquisition unit, configured to acquire the retroreflection coefficient of the road marking; and a visibility evaluation unit, configured to evaluate the nighttime visibility of the road marking based on the acquired retroreflection coefficient and the determined retroreflection coefficient threshold.

[0128] In an embodiment of the present invention, a marking setting device is also provided, which may include: an evaluation unit, configured to evaluate the nighttime visibility of the marking by using the nighttime visibility evaluation method and / or device of the embodiment of the present application; and a marking unit, configured to re-mark the marking if the nighttime visibility of the marking does not meet predetermined requirements.

[0129] Under the teachings of the present invention, features of the method embodiments may be combined with the device embodiments in a non-contradictory manner to obtain new embodiments, and features of the device embodiments may also be combined with the method embodiments in a non-contradictory manner to obtain new embodiments, which fall within the scope of the present invention.

[0130] Therefore, the scheme provided by the embodiment of the present invention effectively realizes the visibility evaluation of road traffic markings at night based on the driver's safety vision needs, and can be used to obtain the visual distance that meets the driver's nighttime visual needs and the minimum retroreflection coefficient requirements of different types of markings, so as to more effectively evaluate the nighttime visibility of road traffic markings in the operational stage. On the one hand, this scheme makes up for the unreasonable visibility evaluation index of road traffic markings at night, and on the other hand, enriches the content of the visibility evaluation method of road traffic markings at night. The evaluation of the visibility of road traffic markings at night according to the scheme provided by the embodiment of the present invention can make the road traffic markings in the operational stage better meet the actual driving needs of drivers.

[0131] As an explanation but not limitation, if two objects are placed next to each other, in order to distinguish them, there should be a certain difference in brightness or chromaticity. If the difference is smaller than this, the human eye cannot distinguish them. Therefore, the target object can only be seen when the contrast between the target object and the background is large enough. The road lighting environment is poor at night, and there is not much visual information for the driver to refer to. It is necessary to identify the markings through the brightness or chromaticity contrast between the markings and the road background, and obtain the lane boundary and the linear induction information of the road ahead. The brightness of the target object is determined by the amount of light reflected from the surface of the target object into the human eye. When the road background is considered to be a black material with a constant and uniform reflection coefficient, the visibility of the markings depends entirely on their own brightness and chromaticity.

[0132] In some embodiments, the marking line mainly includes paint and glass beads embedded in the paint. Figure 6 It is schematically shown that part of the vehicle headlight beam irradiated on the surface of the marking line will be reflected back to the driver's eyes through the paint and glass beads in the marking line, wherein the glass beads play a major role in allowing the driver to see the marking line. In the embodiment of the present application, when light is reflected, it does not leave the light source and goes away, but returns to the direction of the light source. This reflection phenomenon is defined as retroreflection of light, and in the embodiment of the present application, the retroreflection coefficient can be used to characterize the retroreflection ability of the marking line to the vehicle headlight beam.

[0133] In addition, the inventors also realized that the nighttime visible distance of the markings is related to the width of the markings. Figure 6 As a further explanation but not limitation, since the edge line on the road is a rectangular line, it appears as a plane in the driver's field of vision. If the width of the marking line with the same retroreflection coefficient is different, the total amount of light entering the driver's eyes through retroreflection per unit longitudinal length of the marking line is also different, that is, the brightness of the marking line in the human eye is also different.

[0134] In addition, the colors of the longitudinal markings on existing highways are usually white and yellow. White markings indicate the right of way for vehicles in the same lane, while yellow markings indicate the right of way for vehicles in the opposite lane. The inventors also realized that the chromaticity ranges of different marking colors are specified in domestic and foreign standards, indicating that the chromaticity difference between markings of different colors and the road surface is different. Therefore, the effect of the color of the markings on the visibility of the markings should also be considered.

[0135] Furthermore, the inventors realize that in the specific environment of night, the ambient brightness is extremely low and the background is all black. Many factors will affect the visibility of the markings, directly affecting the driver's judgment of the road conditions, and indirectly affecting the safety of their driving and the smoothness of the road. Here, the inventors realize that the visibility of the markings at night is mainly achieved by the retro-reflective characteristics of the markings. The driver identifies the markings through the directional reflective characteristics generated by the car headlights shining on the reflective markings. The retro-reflective coefficient is a key optical parameter for measuring the visibility of the markings at night. In addition to the retro-reflective brightness coefficient of the markings, the width and color of the markings will also affect the visibility of the markings at night. Although these factors will not change the retro-reflective brightness coefficient of the markings, the width and color of the markings directly affect the driver's visual recognition, which can also affect the visibility of the markings at night. The distance of the visual recognition distance can directly reflect the quality of visibility, and the visual recognition distance can be used as an indicator to quantify visibility. Therefore, the visual recognition distance is used as an indicator to evaluate the visibility of the markings at night.

[0136] Therefore, in the embodiment of the present invention, by constructing a retroreflection coefficient model based on marking features such as marking width and / or color, the nighttime visibility of the marking can be effectively evaluated.

[0137] In order to further describe various embodiments of the present invention, so as to show how to evaluate the nighttime visibility of the marking based on the obtained retroreflection coefficient model in different embodiments to meet the driver's safety visual recognition needs for nighttime driving, the construction of the relevant retroreflection coefficient model and the related tests and analyses will be described in the following in the form of specific embodiments. Here, the various features in the specific embodiments below can be combined with the various embodiments described above in a non-contradictory manner to obtain new embodiments. In particular, the formulas of the specific embodiments below can be combined with the various embodiments described above to obtain new embodiments, which fall within the scope of the invention.

[0138] Example

[0139] In this embodiment, in order to enable road traffic markings to meet the safety vision needs of nighttime drivers during the operation stage, the following tests and processing are conducted on the nighttime drivers' vision needs for road traffic markings and the nighttime drivers' vision for different types of markings to obtain a corresponding model for evaluating the nighttime visibility of the markings.

[0140] like Figure 6 As shown, since the edge line on the road is a rectangular line, and as the driver drives close to the line marking, the line marking appears in the driver's field of vision, and the state of the surface is presented in this driving field of vision.

[0141] Furthermore, at night, under the condition of only vehicle headlights, the markings visible in the driver's field of vision are rectangular surfaces composed of horizontal lines that form a brightness or chromaticity contrast with the road surface. Due to the characteristic that the vehicle headlights have their illumination decaying with distance, the brightness of each horizontal line of the markings from near to far along the longitudinal direction is successively reduced until the brightness difference with the road surface is equal to the human eye resolution threshold, and the markings farther away are not visible. Thus, the distance between the driver's position (position A) and the near-end position (position B) of the farthest marking that the driver can see can be defined as the visible distance of the markings (not indicated), which represents the intuitive feeling of the actual road markings obtained from the driver's eye recognition angle. The distance of the visible distance indicates the quality of the visibility of the markings. The farther the visible distance, the better the visibility of the markings. Thus, the embodiment of the present application uses the visible distance of the markings as an indicator for evaluating the visibility of the markings at night, and studies the influence of the retroreflection coefficient, width and color of the markings on the visibility of the markings at night.

[0142] Based on the above analysis of the state changes of the markings in the driver's field of vision during driving, the marking visibility status is graded, as shown in Table 1. Considering the nighttime visibility function of the markings, the standard for meeting the driver's visibility requirements is to meet the Level 2 requirements.

[0143] Table 1 Evaluation table of road marking visual status

[0144]

[0145] In this embodiment, in order to determine the driver's recognition law of different retroreflection coefficients, different widths, and different colors of markings in a night environment, the following test is conducted to construct a related retroreflection coefficient model. More specifically, in order to explore the driver's recognition characteristics of the markings at night and ensure the driver's safe recognition of the road markings, the driver's recognition distance of the road traffic markings is used as an indicator for evaluating the visibility of the markings at night. Through the static recognition test of the markings under different marking conditions at night, the correlation between the retroreflection coefficient and the driver's recognition distance is studied, as well as the influence of the marking width and the marking color on the nighttime visibility of the markings when the retroreflection coefficient is certain, and a model for evaluating the nighttime visibility of the markings is constructed accordingly.

[0146] Test environment

[0147] Since the driving position in my country is on the left side of the vehicle and the driver drives in the right lane, the road shoulder is usually outside the edge line of the right marking. Under the same conditions, the driver's recognition of the right marking is more unfavorable. According to the principle of the most unfavorable recognition and to avoid the influence of weather conditions on the test results, the test was conducted on a 200m long and 7.5m wide two-way two-lane rural road. The road surface is dry, there is no street lighting, and it has a flat and straight line condition. The marking is placed at the right edge line of the driving lane. The plane diagram of the test section is as follows: Figure 7 As shown, in order to avoid the influence of natural light and rural road traffic on the experiment, the experiment was carried out after 22:00 in the evening.

[0148] Test markings

[0149] According to the requirements of "Road Traffic Signs and Markings" (GB 5768.3-2009), road traffic markings are generally white and yellow; "Road Traffic Marking Quality Requirements and Test Methods" (GB / T 16311-2009) also stipulates the retro-reflective performance requirements of white and yellow road traffic markings; in addition, among the markings drawn on the road, line widths of 15cm and 20cm are the most common. Based on the design and use types of current highway markings, the marking samples used in this test are white and yellow in color, with marking widths of 15cm and 20cm. Four types of marking templates are made. The template substrate is aluminum plate, and the template size is 100cm×15cm and 100cm×20cm. Markings with 8 types of retro-reflective coefficients are drawn on each type of aluminum plate. By sprinkling glass beads with different refractive indices or different particle size ratios, the retro-reflective coefficient of the markings is between 20 and 500mcd.m. -2 .lx -1 The construction process is strictly controlled to ensure that the thickness of the 32 test markings is the same and within the range of 0.4mm to 2.5mm. The specific data of different samples after actual measurement are shown in Table 2 below.

[0150] Table 2 Marking data table

[0151]

[0152] Test vehicle

[0153] Since the eye height and headlight height of drivers of large and small vehicles are different, the field of vision of small vehicles is lower than that of large vehicles, and the headlight illumination distance of vehicles is closer. According to the principle of the most unfavorable visual recognition, a typical small passenger car was selected as the test vehicle. The body size, headlight installation height, horizontal distance between the headlight and the driver's eyes, and the relative position of the driver in the car of different models of small passenger cars are different, so a typical test model was selected accordingly.

[0154] Test driver

[0155] Taking into account the age and gender ratio of drivers, 25 male drivers and 11 female drivers were randomly selected around the test site by convenient sampling. The age distribution ranged from 20 to 50 years old, as shown in Table 3. The selected passenger car drivers had a naked or corrected visual acuity of 4.9 or above in both eyes, and had no eye diseases such as color blindness or color weakness. In addition, since the test was conducted at night, the test drivers were informed one week in advance that they should adjust their work and rest schedule according to the test period. They were required to rest well, react normally, and not drink alcohol or take medicine, so as to ensure that the test drivers could maintain a good mental state and normal physiological and psychological reactions during the test.

[0156] Table 3 Overview of the test drivers

[0157]

[0158] Test steps

[0159] The subjects were trained before the test to ensure that each subject was familiar with the test driving task and the test officially began after two rounds of training.

[0160] The specific test process is as follows:

[0161] 1) Test environment layout. The marking board is placed on the east side of the test section, and the test vehicle is placed on the west side of the test section. The 32 marking samples are numbered 1 to 32, and the No. 1 marking is placed on the inside of the right edge line of the lane. The tester records the information of this marking board.

[0162] 2) Test subject preparation. The test subject sits in the driver's seat and adjusts the seat to a height of 1.2m with the help of the tester. The test subject wears a seat belt. The vehicle is started and the high beam is turned on. The tester records the test subject's age, gender and other information.

[0163] 3) Subjects’ visual recognition task: The driver slowly drives the vehicle from a distance to the marked area and visually recognizes it, with a speed of 0-5 km / h, driving normally in the lane according to driving habits. When a horizontal line appears in the subject’s field of vision, the driver stops the vehicle.

[0164] 4) Record data. The tester uses a distance meter to measure the longitudinal distance from the driver to the near end of the marking and records it.

[0165] 5) Replace the line markings with different numbers, repeat steps 2) to 4), and obtain the driver's visual recognition data for line markings No. 1 to No. 32 in sequence.

[0166] 6) The driver was changed and steps 2) to 5) were repeated, and finally 1152 sets of test data on the visual recognition results of different drivers for different markings were obtained.

[0167] Thus, the visual recognition data of different drivers under different marking characteristics (color and width) are obtained, which includes a plurality of different retroreflection coefficients and a plurality of corresponding different viewing distances.

[0168] Analysis and model construction of the relationship between retroreflection brightness coefficient and driver's visual distance

[0169] In this specific embodiment, in order to reduce the influence of external factors on the test drivers and improve the accuracy and effectiveness of the test data, the test can be repeated on different drivers during the test process. When processing and analyzing the test data, the sample size of abnormal vision and large error is eliminated. Finally, the 36 small passenger car drivers are obtained for the width of 15cm and 20cm and the retroreflection brightness coefficient R L The range is 20~460mcd.m -2 .lx-1 A total of 1152 sets of nighttime visual recognition test data of white and yellow markings were collected. In this specific embodiment, according to the requirement of traffic engineering that the sample size meets the driving needs of more than 85% of drivers, the visual recognition distance that 85% of the tested drivers can clearly see is taken as the effective visual recognition distance, and the following test results are obtained, as shown in Table 4 below.

[0170] Table 4 Test results data table

[0171]

[0172] The night vision test data of 36 drivers under different retroreflection coefficients, different colors, and different widths of markings were sorted and analyzed, and the correlation between the retroreflection coefficient of the markings and the driver's vision distance was obtained, that is, the sample point diagram of the driver's vision distance changing with the retroreflection coefficient of the markings, as shown in Figure 2. Figure 8 (for white markings) and Fig. 9 (as shown by the yellow line).

[0173] According to the distribution of test data, a variety of fitting functions can be used, such as linear function, quadratic function, exponential function, power function and logarithmic function, to fit the data and analyze them. The logarithmic function model with the largest determination coefficient is selected as the relationship model between the retroreflection coefficient of the marking and the visual distance. The fitting degree of the four models is good. The relationship model between the retroreflection coefficient and the visual distance of the white 15cm, white 20cm, yellow 15cm and yellow 20cm markings is shown in equations ① to ④.

[0174] ①White 15cm

[0175] f 1 (x) = 29.122ln(x) - 53.955

[0176] ②White 20cm

[0177] f 2 (x) = 27.413ln(x) - 34.402

[0178] ③ Yellow 15cm

[0179] f 3 (x) = 28.94ln(x) - 54.188

[0180] ④Yellow 20cm

[0181] f 4 (x)=28.468ln(x)-42.526.

[0182] Where f(x) is the driver's visual distance of the marking, m; x is the retroreflection coefficient of the marking (mcd.m-2 .lx -1 ), where x∈(0,∞).

[0183] Accordingly, the fitting curves of the retroreflection coefficient and the visual recognition distance for the white marking line and the yellow marking line according to the embodiments of the present application are respectively as follows: Fig.10 and Fig.11 shown.

[0184] Therefore, the safe sight distance at different speeds and the nighttime visibility evaluation index thresholds of different types of road traffic markings are determined.

[0185] For example, based on the multiple retroreflection coefficient models of the marking retroreflection coefficient and the visible distance established in this embodiment, the retroreflection coefficient thresholds of the markings with different characteristics (color and width) for different specified vehicle speeds can be calculated using the safe preview distance of 3.65s, such as the retroreflection coefficient thresholds under different speed limits, as shown in Table 5, which can be used to evaluate the nighttime visibility of road markings, thereby providing a basis for the maintenance of the markings during operation.

[0186] Table 5 Retroreflection coefficient thresholds for different types of markings

[0187]

[0188] In the embodiment of the present application, the night visibility of the marking is evaluated by using the retroreflection coefficient model based on the marking characteristics (color and width), thereby avoiding the problems existing in the current night visual method and the measured retroreflection brightness coefficient method. For example, the night visual method does not have an exact measurement index, and the subjective factors vary greatly, resulting in an unconvincing evaluation result. However, the factors that affect the night visibility of road traffic markings are not only the retroreflection coefficient, and it is not reasonable to rely solely on this indicator to evaluate the night visibility of the markings. On the contrary, the present application provides different retroreflection coefficient models for different marking characteristics, and accordingly determines the corresponding retroreflection coefficient threshold requirements based on the specified vehicle speed, so that the highway traffic markings in the operation stage can meet the driver's night safety recognition needs, and meet the night driver's recognition rules for different types of markings, thereby obtaining a night visibility evaluation method for highway traffic markings that meets the driver's safety recognition needs, thereby providing strong support for the night visibility evaluation of highway traffic markings, in order to achieve a safe, comfortable and reasonable night road traffic marking setting technology.

[0189] Unless explicitly stated, the actions or steps of the methods, programs, and embodiments of the present invention do not have to be performed in a specific order and can still achieve the desired results. In some implementations, multitasking and parallel processing are also possible or may be advantageous.

[0190] In this article, multiple embodiments of the present invention are described, but for the sake of brevity, the description of each embodiment is not exhaustive, and the same or similar features or parts between the embodiments may be omitted. In this article, "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" are meant to be applicable to at least one embodiment or example according to the present invention, but not all embodiments. The above terms do not necessarily mean to refer to the same embodiment or example. In the absence of contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0191] The exemplary systems and methods of the present invention have been specifically shown and described with reference to the above embodiments, which are merely examples of the best modes for implementing the present systems and methods. It will be appreciated by those skilled in the art that various changes may be made to the embodiments of the systems and methods described herein when implementing the present systems and / or methods without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A method for evaluating the nighttime visibility of a road marking, characterized in that: include: Based on a prescribed vehicle speed on a road with markings, determining a safe sight distance at the prescribed vehicle speed; According to a retroreflection coefficient model in which the sight distance varies with the retroreflection coefficient, a retroreflection coefficient threshold of the marking is determined based on the safe sight distance and marking characteristics, wherein the marking characteristics include marking color and / or width, Wherein, the inverse reflection coefficient model is one or more selected from a linear function model, a quadratic function model, an exponential function model, a power function model and a logarithmic function model, The inverse reflection coefficient model includes a plurality of different models based on different marking line characteristics, and is shown in the following formula: f i (x)=A i ln(x)-B i Where f(x) represents the viewing distance, i refers to different models corresponding to different marking characteristics, x represents the retroreflection coefficient of the marking, A and B are positive constants, The multiple models are shown in the following formula: ① For the marking line with the first color and the first width: f1(x)=29.122ln(x)-53.955 ②For the marking line with the first color and the second width: f2(x)=27.413ln(x)-34.402 ③For the marking line with the second color and the first width: f3(x)=28.94ln(x)-54.188 ④ For the marking line with the second color and the second width: f4(x)=28.468ln(x)-42.526; Get the retroreflection coefficient of the marking line; The nighttime visibility of the marking is evaluated based on the acquired retroreflection coefficient and the determined retroreflection coefficient threshold.

2. The method for evaluating the nighttime visibility of road markings according to claim 1, characterized in that: Also includes: The retroreflectance model is constructed.

3. The method for evaluating the nighttime visibility of road markings according to claim 2, characterized in that: Constructing the inverse reflection coefficient model includes: Acquiring visual recognition data of a plurality of drivers for markings, wherein the visual recognition data includes a plurality of different viewing distances corresponding to a plurality of different retroreflection coefficients under different marking features; The retroreflection coefficient model is generated by fitting the visual recognition data.

4. The method for evaluating the nighttime visibility of road markings according to claim 3, characterized in that: Obtain the visual recognition data of different types of road markings by multiple different drivers, including: S1211: For each of the plurality of marking colors and widths, provide a plurality of test markings having a different coefficient of retroreflection; S1213: placing one of the plurality of test markings on the road as the marking to be tested or covering the remaining test markings other than the marking to be tested; S1214: one of the multiple drivers drives the vehicle slowly with the high beam turned on towards the line to be tested from a distance until the line to be tested appears as a horizontal line in the driver's field of vision; S1215: Acquire the distance between the vehicle and the marking line to be measured when a horizontal line appears in the driver's field of vision as the sight distance corresponding to the retroreflection coefficient of the marking line to be measured; S1216: for each test marking line, repeat steps S1214 to S1215 until completion; S1217: For each driver, repeat steps S1213 to S1216 until completion.

5. A marking line setting method, characterized in that: include: Evaluating the nighttime visibility of a road marking by the method for evaluating the nighttime visibility of a road marking according to any one of claims 1 to 4; If the nighttime visibility of the marking does not meet the predetermined requirements, the marking is redrawn.

6. The marking line setting method according to claim 5, characterized in that: Re-marking the lines, including: Adjust the refractive index and / or particle size ratio of the reflective particles incorporated into the marking material.

7. A road comprising a plurality of marking lines, characterized in that: At least one of the plurality of marking lines is set according to the marking line setting method according to claim 5 or 6.

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