A method and device for measuring ETC gantry lighting glare

Abstract

A method and device for measuring ETC gantry lighting glare belongs to the field of highway environmental lighting detection. The device includes a locator, a reflection signal demodulator, a reflection signal receptor, a transmission signal modulator, a signal transmitter, a transmission signal demodulator, a transmission signal receptor, a transmissive and reflective mirror group, a detector, an upper vertical plane illuminance detector, a camera, and a switcher. The present invention measures the reflectivity of the ground below the ETC gantry and the ground brightness to obtain a calculation formula for the ground brightness, thereby achieving the acquisition of ground brightness at close range and solving the problem of excessive external stray light interference caused by using a luminance meter or the like to measure brightness at a long distance, and the reduced measurement accuracy of the luminance meter at a long distance. By obtaining the fill light brightness at different orders of magnitude through switch blades with different light transmittances, the sensitivity advantages of the left and right cameras in high-brightness areas and low-brightness areas are combined, reducing system errors and obtaining an accurate comprehensive illumination value.

Description

Technical Field

[0001] The invention belongs to the field of highway environment lighting detection. Background Art

[0002] Threshold increment: When a glare source appears, the percentage by which the contrast between an object and its background needs to be increased in order to achieve the same good viewing conditions. It is usually expressed as TI and is a quantitative indicator of the glare of lamps such as road lamps and ETC gantry fill lights.

[0003] ETC gantry lighting: The lighting in the ETC gantry system modifies the ambient light near the gantry, enabling the monitoring system to accurately capture license plate information or in-vehicle images. This lighting typically includes automatic license plate recognition (AVR) and traffic monitoring imaging (TVM) fill-in lighting, collectively referred to as fill-in lighting.

[0004] With the completion of the elimination of provincial toll booths on expressways and the construction of a strong transportation nation and the deepening of toll road system reform, ETC gantry systems have been widely used. Among them, lighting systems such as fill lights are an important component of the ETC gantry image recognition and monitoring system.

[0005] The traffic technical monitoring imaging fill light device is installed on the ETC gantry, and the vertical height from the target road is generally 6m. The fill light device is installed on the upper side of the target road. The spatial angle formed by the reference axis of the traffic technical monitoring imaging fill light device and the dividing line between the two roads is equal to 20°, and the number of devices installed per lane is 1.

[0006] The highway vehicle license plate video automatic recognition and fill-light device is installed on the ETC gantry, with a vertical distance of 6.5m from the target road. It is installed directly above the center line of the target road, and one is installed per lane.

[0007] Figure 3 Here, S1 is the target road, S2 is the ETC gantry, S4 is the road adjacent to the target road, S9 is the dividing line between the two roads, S5 is the highway license plate automatic recognition and fill-in lighting device, S6 is the traffic technical monitoring imaging fill-in lighting device, S8 is the reference axis of the traffic technical monitoring imaging fill-in lighting device, and S7 is the centerline of the target road. α is the spatial angle between the reference axis of the traffic technical monitoring imaging fill-in lighting device and the dividing line between the two roads, and its value is 20°.

[0008] However, during the operation of the ETC gantry system, glare caused by the inappropriate selection and configuration of nighttime lighting systems, particularly fill lights, has sparked heated debate. At high speeds, temporary blindness caused by the glare of some ETC gantry lighting systems can lead to serious traffic accidents. Fill light glare has become a hot topic. In 2021, the Ministry of Transport, in response to public concerns, organized regional highway network monitoring and gantry equipment inspections, and urged some provinces to further optimize gantry fill lights to mitigate the impact of light intensity within a certain distance on nighttime driving comfort.

[0009] Glare is a visual condition caused by an unsuitable brightness distribution or range within the field of view, or by extreme brightness contrast, which can cause discomfort or impair the ability to observe objects or details. Glare can be categorized by its effects as either discomfort glare or disabling glare. Glare is essentially a combination of photometry and optometry, primarily manifesting as the physiological response of the human eye to changes in external light. Research indicates that long-term exposure to poor lighting, such as inappropriate illumination, uneven light distribution, and excessive glare, can be extremely harmful to human health. Therefore, accurately measuring glare can effectively prevent and avoid safety issues.

[0010] Glare in road lighting is often quantitatively characterized using threshold increments. Recently, researchers have also proposed using threshold increments to characterize the glare level of ETC gantry fill lights. Currently, there are no commercially available technical solutions for measuring glare from ETC gantry fill lights. Similar technical solutions can be used to measure glare from streetlights. Traditional glare measurement methods use a combination of traditional equipment such as illuminometers, luminance meters, and tape measures. Due to the slow response speeds of illuminometers and luminance meters, measurements must be made in a stationary state. Other methods involve measuring streetlight glare by developing dedicated software to control cameras or imaging luminance meters, and then calculating and obtaining the threshold increment using a position measurement device. These devices are also known as glare testers.

[0011] Current technology has the following shortcomings:

[0012] 1) Existing technology cannot measure the glare of ETC gantry fill lights. The placement of ETC gantry fill lights is completely different from that of road street lights. ETC gantry fill lights are placed above the gantry that crosses the road, while road street lights are placed on the roadside. ETC gantry fill lights are electromechanical facilities on highways. Highways do not have street lights, and the road surface brightness is very low, generally not exceeding 0.5cd / m 2 , and street lamps are electromechanical facilities on the road. Due to the lighting of adjacent street lamps, the ground brightness is higher, at 1.5cd / m 2Therefore, the impact of ETC gantry fill light and road lamp glare on the driver's vision is completely different.

[0013] 2) Currently, conventional glare measurement instruments use static measurements. This involves standing still several meters from the streetlight being measured, capturing a still image, and calculating the brightness at various points within the image to determine the streetlight's threshold increment. This results in the need to close roads to traffic during glare measurement, impacting normal traffic flow.

[0014] 3) The operation process is cumbersome, time-consuming, and the amount of data is too large. Manual real-time point measurement is required. The measurement results obtained are easily affected by subjective factors such as the state of the inspector and the point placement habits, which will invisibly lead to large errors in the test results. Therefore, traditional manual point measurement technology can no longer meet the needs of efficient, real-time, and accurate on-site testing.

[0015] The present invention realizes the glare measurement of the ETC gantry fill light and realizes the measurement in a dynamic state. When the present invention is used to perform the glare measurement of the ETC gantry fill light, there is no need to block traffic.

[0016] The present invention is simple to operate and uses an integrated device to achieve the measurement of the threshold increment, a quantitative evaluation index of glare. The integrated device can obtain the observation position information required for the threshold increment calculation, the illuminance information at the simulated human eye, and the ground brightness information.

[0017] The present invention requires less time. Using conventional methods to measure the glare of a streetlight, statistics show that the fastest measurement takes about 30 minutes. However, using the present invention to measure the glare of an ETC gantry fill light, statistics show that it generally only takes 3 minutes. Summary of the Invention

[0018] The ETC gantry lighting glare measuring device of the present invention is mainly composed of a locator, a data processing module, a reflection signal demodulator, a reflection signal receptor, a transmission signal modulator, a signal transmitter, a transmission signal demodulator, a transmission signal receptor, a transparent and reflective mirror group, a ground-off detector, a frame-off detector, an upper vertical plane illumination detector, a left camera, a middle camera, a right camera, a middle camera light tube, a switcher, a switcher controller, a support frame, a reference horizontal frame and the like. The hardware connection diagram is shown in FIG. Figure 1 shown.

[0019] Figure 1In the figure, 1 is the locator, 2 is the data processing module, 3-1 is the reflection signal demodulator, 3-2 is the reflection signal receptor, 4-1 is the transmission signal modulator, 4-2 is the signal transmitter, 5-1 is the transmission signal demodulator, 5-2 is the transmission signal receptor, 6 is the transparent and reflective mirror assembly, 7 is the ground clearance detector, 8 is the frame clearance detector, 9 is the upper vertical illumination detector, 10 is the left camera, 11 is the center camera, 12 is the right camera, 13 is the center camera light tube, 14 is the switcher, 15 is the switcher controller, 16 is the support frame, 17 is the reference horizontal frame, S1 is the target road, S2 is the ETC gantry, h is the vertical distance between the frame clearance detector and the ETC gantry, and d is the vertical distance between the ground clearance detector and the ground. The ground described in the figure is assumed to be level.

[0020] The locator can be a positioning device based on a GPS receiving module or a positioning device based on a BDS receiving module to obtain the positioning information of the device.

[0021] The data processing module can be a computer, an industrial computer, a single-chip microcomputer, etc., which collects data output by the locator, reflection signal demodulator, transmission signal modulator, ground lift detector, frame lift detector, upper vertical plane illumination detector, left camera, middle camera, right camera, etc. through wired or wireless means, and controls the transmission signal demodulator, switch controller and other parts.

[0022] The reflected signal demodulator is a signal demodulation circuit that demodulates the signal output by the reflected signal receptor, and the demodulation method corresponds to the modulation method.

[0023] The transmitting signal modulator is a signal modulation circuit that controls the signal transmitter to emit a modulated optical signal. The modulation method can be trigonometric function, etc.

[0024] The transmitting signal demodulator is a signal demodulation circuit that demodulates the signal output by the transmitting signal receptor. The demodulation method corresponds to the modulation method.

[0025] The signal transmitter is a component that emits optical signals, preferably a single-wavelength laser, and the wavelength can generally be selected from the infrared band, such as 905nm and 1550nm, which have relatively weak intensity in the solar spectrum.

[0026] A reflective mirror assembly consists of a lens with a reflectivity of m1% and a transmittance of m2%, and a corresponding bracket. The basic principle can be to glue two lenses of different refractive indices together, so that one lens surface reflects light while the other transmits it. Alternatively, an optical coating can be applied to one lens surface, so that one surface reflects light while the other transmits it. m1 + m2 = 100.

[0027] The central axis of the light beam emitted by the signal transmitter passes through the center point of the transmissive and reflective mirror assembly. The energy of the light beam emitted by the signal transmitter is p. The m2% portion passes through the transmissive and reflective mirror assembly, reflects off the ground, and enters the reflection signal receptor. After demodulation by the reflection signal demodulator, the reflected light energy p2 is obtained. The m1% portion of the light beam emitted by the signal transmitter is reflected by the transmissive and reflective mirror assembly and enters the transmission signal receptor. After demodulation by the transmission signal demodulator, the sensed light energy p1 is obtained.

[0028] By using a single-wavelength laser to transmit signals and combining signal modulation and demodulation, external ambient light interference is avoided.

[0029] The ground clearance detector is a component that measures the vertical distance from the ground. It can be a laser ranging module or an ultrasonic ranging module.

[0030] The distance detector is a device for measuring the glare of the ETC gantry lighting. It is a component that measures the vertical distance from the ETC gantry when passing under the ETC gantry. It can be a laser ranging module, an ultrasonic ranging module, etc.

[0031] The measuring surface on the lower side of the ground detector and the measuring surface on the upper side of the frame detector, the measuring surface on the upper side of the upper vertical plane illuminance detector, the photosensitive surface on the lower side of the reflection signal receptor, the luminous surface on the lower side of the signal transmitter, and the photosensitive surface on the lower side of the transmission signal receptor are in the same plane.

[0032] The upper vertical surface illuminance detector is an illuminance collection component with a sampling frequency higher than 100Hz.

[0033] The left, center, and right cameras are located on the same horizontal plane and fixed to a reference horizontal frame, facing the same direction. They have identical external dimensions. The sampling frequency of each camera is k, and they can be triggered simultaneously. The center camera is 1.5 meters above the ground, a height typically used in conventional research to describe the driver's eye level. The axes of the left, center, and right cameras are parallel and coplanar, forming a 1° angle with the road axis. The axes of the left, center, and right cameras are oriented horizontally downward relative to the road axis. This simulates the situation where the line of sight passes through the observer's eye in the road's longitudinal plane, 1° downward, assuming the observer's eye level is 1.5 meters above the road. In this scenario, the axes of the left, center, and right cameras, respectively, pass through the left, center, and right cameras in the road's longitudinal plane, 1° downward.

[0034] The switch is a circular ring made of glass, divided into eight equal parts, symmetrically along the axis. Adjacent sections have different transmittances, while separated sections have the same transmittance. The transmittance of sections with higher transmittance is hn, while that of sections with lower transmittance is ln. Transmittance is quantified by placing different sections of the ring between a light source and a standard luminance meter. If the brightness output by the standard luminance meter remains unchanged before and after placement, the transmittance is recorded as 100%. If the brightness output by the standard luminance meter after placement is 0, the transmittance is recorded as 0%. In other words, the transmittance is the ratio of the brightness output of the standard luminance meter after placement to the brightness output of the standard luminance meter before placement.

[0035] Under the control of the switch controller, the switch rotates around the center point of the switch at a speed of v revolutions per second. k≥16v.

[0036] The reference horizontal frame is connected to the support frame, and the support frame is connected to the switch controller. The reference horizontal frame is parallel to the road.

[0037] The central axis of the switch coincides with the central axis of the center camera. The inner diameter of the switch is equal to the lens diameter of the center camera.

[0038] The left and right camera's field of view is blocked by the switch ring.

[0039] The ETC gantry lighting glare measurement device establishes internal spatial coordinates. The midpoint of the center camera lens is set as point O, with coordinates of (0, 0); the line passing through the midpoints of the center camera lens, the left camera lens, and the right camera lens is set as the x-axis, and the direction from the left camera to the right camera is the positive direction; the central axis of the center camera is set as the y-axis, and the reference horizontal frame is parallel to the x-axis, and the direction from the center camera to the switch is the positive direction.

[0040] The internal spatial coordinates of the positioner are (xd, yd). After each component is installed, its coordinates are measured and the distances between different components are calculated.

[0041] The technical solution flow chart of the method for measuring the glare of the ETC gantry lighting is as follows: Figure 4 shown.

[0042] The ETC gantry lighting glare measuring device is mainly composed of a locator, a data processing module, a reflection signal demodulator, a reflection signal receptor, a transmission signal modulator, a signal transmitter, a transmission signal demodulator, a transmission signal receptor, a transparent and reflective mirror group, a ground-off detector, a frame-off detector, an upper vertical plane illuminance detector, a left camera, a middle camera, a right camera, a middle camera light tube, a switcher, a switcher controller, a support frame, a reference horizontal frame and the like.

[0043] The overall technical solution implementation process is as follows:

[0044] (1) It should be clarified that the fill light can refer to the fill light device for the automatic recognition of highway license plate video or the fill light device for traffic technical monitoring imaging. The threshold increments of the two should be measured and calculated separately. That is, it is necessary to select the corresponding fill light device for measurement, which can be called the selected fill light. When the fill light device for the automatic recognition of highway license plate video is selected as the measurement object, the fill light mentioned below refers to the fill light device for the automatic recognition of highway license plate video; when the fill light device for traffic technical monitoring imaging is selected as the measurement object, the fill light mentioned below refers to the fill light device for traffic technical monitoring imaging.

[0045] (2) The ETC gantry lighting glare measuring device needs to be calibrated before use.

[0046] (3) First, calibrate the illumination. Place the ETC gantry lighting glare measuring device at a distance of 13.75m from the front of the ETC gantry. Here, 13.75m simulates the driver's eyes at a height of 1.5m. When the driver is 13.75m away from the ETC gantry, the fill light on the ETC gantry can be observed. The calculation process is as follows: Assume that the height of the observer's eyes is 1.5m above the road surface, the line of sight passes through the observer's eyes horizontally downward 1° on the longitudinal vertical plane of the road, and the vertical distance between the highway vehicle license plate video automatic recognition fill light device and the road surface is 6.5m. Then, it can be calculated that the distance between the observer and the ETC gantry must be greater than 2.75 (6.5-1.5)m, that is, 13.75m. The vertical distance between the traffic technology monitoring imaging fill light device and the road surface is 6m. Then, it can be calculated that the distance between the observer and the ETC gantry must be greater than 2.75 (6-1.5)m, that is, 12.375m. In order to accurately calibrate the illumination, especially the illumination generated by the automatic recognition fill light device through the highway vehicle license plate video, the ETC gantry lighting glare measuring device is stationary at a distance of 13.75m from the front of the ETC gantry.

[0047] (4) Adjust the switch so that the part of the switch with low light transmittance is just blocked in front of the left camera and the right camera. Install a light shielding tube in front of the probe of the standard-level illuminance meter. The diameter of the light shielding tube is the same as the diameter of the probe, and the length is 3 times the diameter of the probe. Place the probe and light shielding tube of the standard-level illuminance meter in front of the left camera, and align the light shielding tube with the selected fill light, and measure the reference illuminance value ZSL1. Place the probe and light shielding tube of the standard-level illuminance meter in front of the right camera, and align the light shielding tube with the selected fill light, and measure the reference illuminance value ZSR1. Use the left camera and right camera to capture the image at this time, and obtain the electrical signal values ​​of all pixels in the selected fill light part of the image as DL1 and DR1 respectively. Adjust the switch so that the part of the switch with high light transmittance is just blocked in front of the left camera and the right camera. Place the probe and light shielding tube of the standard-level illuminance meter in front of the left camera, and align the light shielding tube with the selected fill light, and measure the reference illuminance value ZSL2. Place the probe and light shield of a standard-grade illuminance meter in front of the right camera, and align the light shield with the selected fill light to measure the reference illuminance value ZSR2. Use the left and right cameras to capture the image at this time, and obtain the electrical signal values ​​DL2 and DR2 for all pixels in the selected fill light portion of the image. Calibrate the left and right cameras, and record the relationship between the selected fill light illuminance value ZCL captured by the left camera and the electrical signal DLn as follows: when the left camera is in front of the low-transmittance portion of the switch, ZCL = DLn*ZSL1 / (DL1 / ln); when the left camera is in front of the high-transmittance portion of the switch, ZCL = DLn*ZSL2 / (DL2 / hn). The relationship between the selected fill light illumination value ZCR collected by the right camera and the electrical signal DRn is recorded as follows: when the part in front of the right camera is the part with low transmittance of the switch, ZCR = DRn*ZSR1 / (DR1 / ln); when the part in front of the right camera is the part with high transmittance of the switch, ZCR = DRn*ZSR2 / (DR2 / hn).

[0048] (5) Then calibrate the position. Use a total station to measure the distance JLS1 between the selected fill light on the front ETC gantry and the middle camera. Use the image data collected by the left camera and the right camera, and use the depth calculation method based on the parallax principle to calculate the distance JLW1 between the selected fill light on the ETC gantry that has not been calibrated and the middle camera. Perform distance calibration, and record the relationship between the calibrated distance measurement result JLYn and the uncalibrated calculation result JLWn as JLYn=JLWn*(JLS1 / JLW1). Use a total station to measure the height LEDh of the selected fill light on the front ETC gantry from the ground, and the lateral deviation LEDw of the selected fill light on the front ETC gantry from the center line of the road. Use the middle camera to collect image data, and extract the number of pixels XSh of the selected fill light from the ground and the number of pixels XSw of the selected fill light from the center line of the road in the image. Perform coordinate calibration, and record the relationship between the calibrated selected fill light height measurement result Lhn and the pixel number Xhn as Lhn = Xhn*(LEDh / XSh). Record the relationship between the calibrated selected fill light lateral deviation measurement result Lwn from the road centerline and the pixel number Xwn as Lwn = Xwn*(LEDw / XSw).

[0049] (6) Recalibrate the brightness. First, use a standard-grade luminance meter to measure the reference brightness value LS of the ground below the ETC gantry. Then move the ETC gantry lighting glare measuring device to the bottom of the ETC gantry. The signal transmitter emits a modulated light beam with a beam energy of p0. m2% of the light passes through the transparent and reflective mirror group, is reflected by the ground below the ETC gantry, is measured by the reflection signal receptor, and is demodulated by the reflection signal demodulator to obtain the reflected light beam energy p20. m1% of the light is reflected by the transparent and reflective mirror group, and then enters the transmission signal receptor, is demodulated by the transmission signal modulator, and obtains the corresponding light beam energy p10. Then p0 = p10 / (m1%). The upper vertical plane illuminance detector measures the illuminance value E10, the ground distance detector measures the distance d0 from the ground, and the distance detector measures the distance h0 from the ETC gantry. Then the brightness value LW of the ground below the ETC gantry is p20(E10h0 2 ) / (p10(h0+d0) 2 The ground brightness measurement result of the calibrated ETC gantry lighting glare measurement device is obtained as LJ=p20(E10h0 2 ) / (p10(h0+d0) 2 )*LS / LW. That is, in subsequent measurements, the ground brightness measurement result is the actual measurement value LC multiplied by the reference brightness value LS recorded during calibration, and then divided by the measurement value LW recorded during calibration.

[0050] (7) When conducting on-site measurement, the ETC gantry lighting glare measuring device is moved from an area 50m away from the ETC gantry to the ETC gantry. The middle camera is located on a plane perpendicular to the road surface and containing the center line of the road. The switch controller controls the switch to rotate at a speed of v revolutions per second, and the left camera, middle camera, and right camera face the direction of the ETC gantry and are triggered to capture images at the same time at a sampling frequency k, where k≥16v. Since the switch is axially symmetrically divided into 8 equal parts, the transmittance of adjacent parts is different, and the transmittance of separated parts is the same. The transmittance of the part with high transmittance is hn, and the transmittance of the part with low transmittance is ln. When the switch rotates, the left camera and the right camera can capture images that are simultaneously blocked by the part with high transmittance, and can also capture images that are simultaneously blocked by the part with low transmittance. The image data captured by the left camera and the right camera are used, and the depth calculation method based on the parallax principle is used in combination with calibration to obtain the distance JLYn between the selected fill light on the ETC gantry and the middle camera. The image data collected by the central camera is combined with calibration to obtain the height measurement result Lhn of the selected fill light and the lateral deviation measurement result Lwn of the selected fill light from the road centerline. The angle formed by the line connecting the center point of the central camera and the selected fill light and the axis of the central camera is then calculated. The left camera and the right camera are used to measure the comprehensive illumination value ZCZ = (ZCR + ZCL) / 2.

[0051] (8) When the measuring device for the ETC gantry lighting glare passes under the ETC gantry. The signal transmitter emits a modulated light beam with a beam energy of p, m2% of the light passes through the transparent and reflective mirror group, is reflected by the ground under the ETC gantry, is measured by the reflection signal receptor, and is demodulated by the reflection signal demodulator to obtain the reflected light beam energy p2. m2% of the light is reflected by the transparent and reflective mirror group, and then enters the transmission signal receptor, is demodulated by the transmission signal modulator, and obtains the corresponding light beam energy p1. Then p=2*p1. The upper vertical plane illuminance detector measures the illuminance value E1, the ground detector measures the distance d from the ground, and the distance detector measures the distance h from the ETC gantry. The ground brightness measurement result is p2(E1h 2 ) / (p1(h+d) 2 )*LS / LW.

[0052] (9) Calculate the threshold increment of the selected fill light: BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Hardware connection diagram

[0054] Figure 1In the figure, 1 is a locator, 2 is a data processing module, 3-1 is a reflection signal demodulator, 3-2 is a reflection signal receptor, 4-1 is a transmission signal modulator, 4-2 is a signal transmitter, 5-1 is a transmission signal demodulator, 5-2 is a transmission signal receptor, 6 is a transparent and reflective mirror group, 7 is a ground clearance detector, 8 is a frame clearance detector, 9 is an upper vertical plane illumination detector, 10 is a left camera, 11 is a middle camera, 12 is a right camera, 13 is a middle camera light tube, 14 is a switcher, 15 is a switcher controller, 16 is a support frame, 17 is a reference horizontal frame, S1 is a target road, S2 is an ETC gantry, h is the vertical distance between the frame clearance detector and the ETC gantry, and d is the vertical distance between the ground clearance detector and the ground. The ground described in the present invention is assumed to be horizontal.

[0055] Figure 2 In the figure, 11 is the center camera, 17 is the reference horizontal frame, S1 is the ground, S3 is the axis of the center camera, and β is the angle formed by the axis of the center camera and the ground, which is 1°.

[0056] Figure 3 This is a schematic diagram of the position of the fill light device in the prior art.

[0057] Figure 3 Here, S1 is the target road, S2 is the ETC gantry, S4 is the road adjacent to the target road, S9 is the dividing line between the two roads, S5 is the highway license plate automatic recognition and fill-in lighting device, S6 is the traffic technical monitoring imaging fill-in lighting device, S8 is the reference axis of the traffic technical monitoring imaging fill-in lighting device, and S7 is the centerline of the target road. α is the spatial angle between the reference axis of the traffic technical monitoring imaging fill-in lighting device and the dividing line between the two roads, and its value is 20°.

[0058] Figure 4 Technical solution flow chart

[0059] Figure 5 Technical solution flow chart of specific example 1 DETAILED DESCRIPTION

[0060] The present invention can be used to measure the threshold increment of the highway vehicle license plate video automatic recognition and fill-in-light device and the traffic technology monitoring imaging and fill-in-light device installed on the ETC gantry. The process is as follows: Figure 5 .

[0061] Referring to the flowchart of Example 1, the implementation process of the technical solution of Example 1 is as follows:

[0062] (1) The ETC gantry lighting glare measurement device is installed on the inspection vehicle. The left camera, center camera, right camera, center camera light tube, switch, switch controller, support frame, reference horizontal frame and other parts are installed at the co-pilot position. The positioner, data processing module and other parts are installed inside the inspection vehicle. The reflection signal demodulator, reflection signal receptor, transmission signal modulator, signal transmitter, transmission signal demodulator, transmission signal receptor, transparent and reflective mirror group, ground clearance detector, frame clearance detector, upper vertical illumination detector and other parts are installed on the side of the inspection vehicle.

[0063] (2) The inspection vehicle is parked 13.75 meters away from an ETC gantry and a standard-grade illuminance meter and total station are used to perform illumination and position calibration. If only the threshold increment of the traffic technology monitoring imaging supplementary lighting device on the ETC gantry is considered, the inspection vehicle can also be parked 12.375 meters away from an ETC gantry for illumination and position calibration.

[0064] (3) Park the inspection vehicle directly under the same ETC gantry and use a standard-grade luminance meter to calibrate the brightness.

[0065] (4) Drive the inspection vehicle towards the target ETC gantry and stop only after passing the target ETC gantry. Use the ETC gantry lighting glare measurement device to collect and calculate the corresponding ETC gantry fill light threshold increment formula.

[0066] The present invention realizes the glare measurement of the ETC gantry fill light and realizes the measurement in a dynamic state. When the present invention is used to perform the glare measurement of the ETC gantry fill light, there is no need to block traffic.

[0067] The present invention is simple to operate and uses an integrated device to achieve the measurement of the threshold increment, a quantitative evaluation index of glare. The integrated device can obtain the observation position information required for the threshold increment calculation, the illuminance information at the simulated human eye, and the ground brightness information.

[0068] The present invention requires less time. Using conventional methods to measure the glare of a streetlight, statistics show that the fastest measurement takes about 30 minutes. However, using the present invention to measure the glare of an ETC gantry fill light, statistics show that it generally only takes 3 minutes.

[0069] The present invention uses a locator, a data processing module, a reflection signal demodulator, a reflection signal receptor, a transmission signal modulator, a signal transmitter, a transmission signal demodulator, a transmission signal receptor, a transparent and reflective mirror group, a ground-lift detector, a frame-lift detector, an upper vertical plane illumination detector, a left camera, a middle camera, a right camera, a middle camera light tube, a switcher, a switcher controller, a support frame, a reference horizontal frame and other parts to form an ETC gantry lighting glare measuring device.

[0070] The present invention proposes a method for measuring the glare of ETC gantry lighting. By measuring the reflectivity of the ground below the ETC gantry and the ground brightness, the calculation formula of the ground brightness is obtained: p2(E1h 2 ) / (p1(h+d) 2 )*LS / LW, it realizes the acquisition of ground brightness at close range, solves the problem of more external stray light interference caused by using a brightness meter to measure brightness at a long distance, and the decrease in the measurement accuracy of the brightness meter at a long distance; by obtaining the fill light brightness at different orders of magnitude through the switch blades with different light transmittance, it combines the sensitivity advantages of the left camera and the right camera in high brightness areas and low brightness areas, reduces the system error, and obtains a more accurate comprehensive illumination value ZCZ=(ZCR+ZCL) / 2. Using the left camera and the right camera, the distance between the ETC gantry fill light and the center camera was measured by binocular vision, and the center camera was used to calculate the height of the ETC gantry fill light and the lateral deviation from the center line of the road. Through three geometric parameters, the angle formed by the line connecting the center point of the center camera and the fill light and the axis of the center camera was calculated. The quantitative measurement of ETC gantry lighting glare was achieved, and the threshold increment formula of the ETC gantry fill light was calculated:

[0071] .3 The present invention uses the on-site ETC gantry for pre-use calibration. There is no need to calibrate in a standard darkroom or geometric metrology laboratory, which improves work efficiency. Since there are no street lights on the highway, the brightness is low at night. Compared with the ETC gantry fill light, other light sources have lower brightness and weaker interference ability, so it is equivalent to treating the site as an open darkroom. When the ETC gantry lighting glare measuring device is stationary at a distance of 13.75m from the front of the ETC gantry, a standard-level illuminance meter is used to obtain a standard illuminance value, and the illuminance measurement capability of the ETC gantry lighting glare measuring device is calibrated; a total station is used to obtain the standard position value of the ETC gantry fill light, and the position measurement capability of the ETC gantry lighting glare measuring device is calibrated. When calibrating the brightness measurement capability of the ETC gantry lighting glare measuring device, first stationary the ETC gantry lighting glare measuring device at a distance of 13.75m from the front of the ETC gantry, and measure the standard value of the ground brightness with a standard-grade luminance meter. Then, place the ETC gantry lighting glare measuring device under the ETC gantry, and use the ETC gantry lighting glare measuring device to collect brightness information. Finally, calibrate the brightness measurement capability of the ETC gantry lighting glare measuring device.

Claims

1. A device for measuring glare from ETC gantry lighting, characterized by: It includes a locator, a data processing module, a reflection signal demodulator, a reflection signal receptor, a transmission signal modulator, a signal transmitter, a transmission signal demodulator, a transmission signal receptor, a transparent and reflective mirror group, a ground-lift detector, a frame-lift detector, an upper vertical plane illumination detector, a left camera, a middle camera, a right camera, a middle camera light tube, a switcher, a switcher controller, a support frame, and a reference horizontal frame; The locator is a positioning device based on a GPS receiving module, or a positioning device based on a BDS receiving module; The data processing module is a computer, industrial computer or single-chip microcomputer, which collects data output by the locator, reflection signal demodulator, transmission signal modulator, ground lift detector, frame lift detector, upper vertical illumination detector, left camera, middle camera and right camera through wired or wireless means, and controls the transmission signal demodulator and switch controller; The reflected signal demodulator is a signal demodulation circuit that demodulates the signal output by the reflected signal receptor. The demodulation method corresponds to the modulation method. The transmitting signal modulator is a signal modulation circuit that controls the signal transmitter to emit a modulated optical signal; The transmission signal demodulator is a signal demodulation circuit that demodulates the signal output by the transmission signal receptor. The demodulation method corresponds to the modulation method. The signal transmitter is the component that emits light signals; The transmissive and reflective mirror assembly is composed of a lens with a reflectivity of m1% and a transmittance of m2% and a corresponding bracket, and m1+m2=100; The central axis of the light beam emitted by the signal transmitter passes through the center point of the transparent and reflective mirror group; the light beam emitted by the signal transmitter has an energy of p, and m2% of it passes through the transparent and reflective mirror group, is reflected by the ground, and enters the reflection signal receptor. After being demodulated by the reflection signal demodulator, the energy of the reflected light is obtained as p2; the light beam emitted by the signal transmitter has an m1% portion that is reflected by the transparent and reflective mirror group and enters the transmission signal receptor. After being demodulated by the transmission signal demodulator, the energy of the sensed light beam is obtained as p1; The ground clearance detector is a component that measures the vertical distance from the ground; The distance detector is a device that measures the glare of the ETC gantry lighting. It measures the vertical distance from the ETC gantry when passing under the ETC gantry. It is a laser ranging module or an ultrasonic ranging module. The measuring surface on the lower side of the ground detector and the measuring surface on the upper side of the frame detector, the measuring surface on the upper side of the upper vertical plane illumination detector, the photosensitive surface on the lower side of the reflection signal receptor, the luminous surface on the lower side of the signal transmitter, and the photosensitive surface on the lower side of the transmission signal receptor are in the same plane; The upper vertical illuminance detector is an illuminance collection component with a sampling frequency higher than 100Hz; The left, center, and right cameras are located on the same horizontal plane and fixed on a reference horizontal frame. The left, center, and right cameras face the same direction. The left, center, and right cameras have the same external dimensions. The sampling frequency of the left, center, and right cameras is k, and they can be triggered to shoot simultaneously. The center camera is 1.5 meters above the ground. The axes of the left, center, and right cameras are parallel to each other and located on the same plane. The plane they form forms an angle of 1° with the road axis, and the axes of the left, center, and right cameras are horizontally downward relative to the road axis. The switch is a circular ring, which is divided into 8 equal parts axially symmetrically. The transmittance of adjacent parts is different, and the transmittance of separated parts is the same. The transmittance of the part with high transmittance is hn, and the transmittance of the part with low transmittance is ln. The switch rotates around the center point of the switch under the control of the switch controller at a speed of v revolutions per second; k ≥ 16v; The reference horizontal frame is connected to the support frame, and the support frame is connected to the switch controller; the reference horizontal frame is parallel to the road; The central axis of the switch coincides with the central axis of the central camera; the inner diameter of the switch is equal to the lens diameter of the central camera; The left and right camera's field of view is blocked by the switch ring.

2. A method for applying the device according to claim 1, characterized in that: The ETC gantry lighting glare measurement device establishes internal space coordinates; the midpoint of the center camera lens is taken as point O, with coordinates of (0, 0); the line passing through the midpoint of the center camera lens, the midpoint of the left camera lens, and the midpoint of the right camera lens is taken as the x-axis, and the direction from the left camera to the right camera is taken as the positive direction; the central axis of the center camera is taken as the y-axis, the reference horizontal frame is parallel to the x-axis, and the direction from the center camera to the switch is taken as the positive direction; The internal space coordinates of the locator are (xd, yd); after each component is installed, its coordinates are obtained by measurement, and the distances between different components are obtained by calculation; The implementation process is as follows: (1) Fill light refers to a fill light device for automatic video recognition of vehicle license plates on highways, or a fill light device for imaging of traffic technology monitoring. The threshold increments of the two should be measured and calculated separately; that is, the corresponding fill light device needs to be selected for measurement, which can be called a selected fill light; when the fill light device for automatic video recognition of vehicle license plates on highways is selected as the measurement object, the fill light mentioned below refers to the fill light device for automatic video recognition of vehicle license plates on highways; when the fill light device for imaging of traffic technology monitoring is selected as the measurement object, the fill light mentioned below refers to the fill light device for imaging of traffic technology monitoring; (2) The ETC gantry lighting glare measurement device needs to be calibrated before use; (3) First, calibrate the illuminance; place the ETC gantry lighting glare measuring device at a distance of 13.75 m from the front of the ETC gantry; (4) Adjust the switch so that the part of the switch with low light transmittance is just blocked in front of the left camera and the right camera; install a light shielding tube in front of the probe of the standard-level illuminance meter, the diameter of the light shielding tube is the same as the diameter of the probe, and the length is 3 times the diameter of the probe; place the probe and light shielding tube of the standard-level illuminance meter in front of the left camera, and align the light shielding tube with the selected fill light, and measure the reference illuminance value ZSL1; place the probe and light shielding tube of the standard-level illuminance meter in front of the right camera, and align the light shielding tube with the selected fill light, and measure the reference illuminance value ZSR1; use the left camera and the right camera to respectively capture the image at this time, and obtain the electrical signal values ​​of all pixels of the selected fill light part in the image, which are DL1 and DR1 respectively; adjust the switch so that the part of the switch with high light transmittance is just blocked in front of the left camera and the right camera; place the probe and light shielding tube of the standard-level illuminance meter in front of the left camera, and align the light shielding tube with the selected fill light, and measure the reference illuminance value ZSL2; place the probe and light shielding tube of the standard-level illuminance meter in front of the left camera In front of the right camera, aim the light shield at the selected fill light and measure the reference illuminance value ZSR2; use the left camera and the right camera to respectively capture the image at this time, and obtain the electrical signal values ​​of all pixels of the selected fill light part in the image, respectively DL2 and DR2; calibrate the left camera and the right camera, and record the relationship between the selected fill light illuminance value ZCL captured by the left camera and the electrical signal DLn as follows: when the front of the left camera is the part with low transmittance of the switch, ZCL=DLn*ZSL1 / (DL1 / ln); when the front of the left camera is the part with high transmittance of the switch, ZCL=DLn*ZSL2 / (DL2 / hn); record the relationship between the selected fill light illuminance value ZCR captured by the right camera and the electrical signal DRn as follows: when the front of the right camera is the part with low transmittance of the switch, ZCR=DRn*ZSR1 / (DR1 / ln); when the front of the right camera is the part with high transmittance of the switch, ZCR=DRn*ZSR2 / (DR2 / hn); (5) Then calibrate the position; use the total station to measure the distance JLS1 of the camera in the distance of the selected fill light on the front ETC gantry; use the image data collected by the left camera and the right camera to obtain the distance JLW1 of the camera in the distance of the selected fill light on the ETC gantry that has not been calibrated, measured by the ETC gantry lighting glare measurement device; Perform distance calibration, and record the relationship between the calibrated distance measurement result JLYn and the uncalibrated calculation result JLWn as JLYn=JLWn*(JLS1 / JLW1); use a total station to measure the height LEDh of the selected fill light on the front ETC gantry from the ground, and the lateral deviation LEDw of the selected fill light on the front ETC gantry from the center line of the road; use the central camera to collect image data, and extract the number of pixels XSh of the selected fill light from the ground and the number of pixels XSw of the selected fill light from the center line of the road in the image; perform coordinate calibration, and record the relationship between the calibrated height measurement result Lhn of the selected fill light and the number of pixels Xhn as Lhn=Xhn*(LEDh / XSh), and record the relationship between the calibrated lateral deviation measurement result Lwn of the selected fill light from the center line of the road and the number of pixels Xwn as Lwn=Xwn*(LEDw / XSw); (6) Recalibrate the brightness; first use a standard-grade luminance meter to measure the reference brightness value LS of the ground below the ETC gantry; Then, the ETC gantry lighting glare measuring device is moved to the bottom of the ETC gantry. The signal transmitter emits a modulated light beam with a beam energy of p0, m2%. The light passes through the transmissive and reflective mirror group, is reflected by the ground below the ETC gantry, and is measured by the reflected signal sensor. The reflected signal is demodulated by the reflected signal demodulator to obtain the reflected beam energy p20. m1% of the light is reflected by the transmissive and reflective mirror group, then enters the transmission signal receptor and is demodulated by the transmission signal modulator to obtain the corresponding beam energy p10; then p0 = p10 / (m1%); The upper vertical illumination detector measures the illumination value E10, the ground distance detector measures the distance from the ground d0, and the distance from the ETC gantry detector measures the distance from the ETC gantry h0. The brightness value LW of the ground below the ETC gantry is p20(E10h0 2 ) / (p10(h0+d0) 2 ); obtain the calibrated ETC gantry lighting glare measurement device ground brightness measurement result LJ = p20 (E10h0 2 ) / (p10(h0+d0) 2 )*LS / LW; that is, in subsequent measurements, the ground brightness measurement result is the actual measurement value LC multiplied by the reference brightness value LS recorded during calibration and then divided by the measurement value LW recorded during calibration; (7) When conducting on-site measurement, the ETC gantry lighting glare measuring device is moved from an area 50 m away from the ETC gantry toward the ETC gantry; The middle camera is located on a plane perpendicular to the road surface and containing the center line of the road; the switch controller controls the switch to rotate at a speed of v revolutions per second, and the left camera, middle camera, and right camera face the direction of the ETC gantry and are triggered to capture images at the same time with a sampling frequency of k, where k ≥ 16v; since the switch is axially symmetrically divided into 8 equal parts, the transmittance of adjacent parts is different, and the transmittance of separated parts is the same, the transmittance of the part with high transmittance is hn, and the transmittance of the part with low transmittance is ln. When the switch rotates, the left camera and the right camera can capture images. The image blocked by the part with high light transmittance can also capture the image blocked by the part with low light transmittance at the same time; the image data collected by the left camera and the right camera are used to obtain the distance JLYn between the selected fill light on the ETC gantry and the middle camera; the image data collected by the middle camera is combined with calibration to obtain the height measurement result Lhn of the selected fill light and the lateral deviation measurement result Lwn of the selected fill light from the center line of the road; and then the angle formed by the line between the center point of the middle camera and the selected fill light and the axis of the middle camera is calculated. The left and right cameras are used to measure the comprehensive illumination value ZCZ = (ZCR + ZCL) / 2; (8) When the ETC gantry lighting glare measuring device passes under the ETC gantry, the signal transmitter emits a modulated light beam with a light beam energy of p,m2% passing through the transmissive and reflective mirror group, reflected by the ground below the ETC gantry, measured by the reflection signal sensor, and demodulated by the reflection signal demodulator to obtain the reflected light beam energy p2; m2% of the light is reflected by the transmissive and reflective mirror group, then enters the transmitting signal receptor and is demodulated by the transmitting signal modulator to obtain the corresponding light beam energy p1; then p=2*p1; the upper vertical plane illuminance detector measures the illuminance value E1, the ground detector measures the distance d from the ground, and the distance from the frame detector measures the distance h from the ETC gantry, then the ground brightness measurement result is p2(E1h 2 ) / (p1(h+d) 2 )*LS / LW; (9) Calculate the threshold increment of the selected fill light:

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