In-situ calibration method and device for vehicle-mounted marking retroreflective measuring instrument

Abstract

The in-situ calibration method and device for vehicle-mounted line retroreflective measuring instrument belong to the field of traffic safety facilities.The device is composed of a calibrated instrument mounting platform, a rotating table and a ring line retroreflective standard device, wherein the calibrated instrument mounting platform can realize the forward, lateral and pitching movement of the calibrated instrument, including a sliding rail, a base, an extension rod, an adjustable flat plate and a support rod; the rotating table is a device for providing corresponding rotating speed for the ring line retroreflective standard device, including a support, a motor, a bearing and a flange; the ring line retroreflective standard device is a carrier of the retroreflective brightness coefficient standard value, including a disc flat plate and coated glass beads. The application also provides a calibration method and the like. The application simulates different driving speeds of the vehicle by different rotating speeds of the rotating table, avoids repeated driving tests, simplifies the work process, improves the calibration work efficiency and has high accuracy.

Description

Technical Field

[0001] This invention belongs to the field of traffic safety facilities. Background Technology

[0002] Retroreflection: Also known as reflection, retrospection, retrograde reflection, retrograde reflection, directional reflection, or reverse reflection, it is a type of reflection in which the reflected light returns from the opposite direction to the incident light.

[0003] Vehicle-mounted road marking retroreflection measuring instrument: An instrument or system mounted on a vehicle that can quickly measure the retroreflection brightness coefficient of road markings at normal driving speeds during the day and night, and certain measurement geometric conditions should be ensured during the measurement process.

[0004] Retroreflective standard for road markings: After being verified or calibrated by a metrology institution, it can be used to calibrate the road marking plate of a vehicle-mounted retroreflective measuring instrument for road markings.

[0005] In-situ calibration: A method of calibrating a vehicle-mounted road marking retroreflection measuring instrument by keeping its spatial position unchanged and causing the road marking standard to move at a speed corresponding to the vehicle speed, thereby simulating the calibration speed and other conditions of the vehicle-mounted road marking retroreflection measuring instrument.

[0006] Road markings, as an irreplaceable traffic safety facility, distinguish lanes and indicate traffic during the day through colored lines and text, and at night, they reflect headlights to indicate the road outline to drivers, playing a vital role in driving safety. Deterioration in the retroreflective performance of road markings poses a potential threat to driving safety; therefore, regular inspection and maintenance are necessary in engineering projects.

[0007] Conventional instruments for testing the retroreflectivity of road markings are handheld retroreflectometers. While accurate, they require temporary road closures, contradicting the principle of "convenience" for traffic flow. Furthermore, manual testing is inefficient. With the increasing demand for testing, handheld retroreflectometers are becoming increasingly inadequate. In recent years, vehicle-mounted retroreflectometers have emerged. Through structural optimization and updated detection algorithms, they can be mounted on vehicles to test the retroreflectivity of road markings. However, as a new type of instrument, the industry is still exploring the accuracy and reliability of its test results.

[0008] Currently, only the National Metrology Station for Road and Bridge Engineering Testing Equipment in China calibrates vehicle-mounted road marking retroreflective measuring instruments based on the "road segment method." Specifically, this involves selecting a flat, straight road and laying a set of pre-assigned (standard) road marking standards along the roadside parallel to the road's direction. The vehicle-mounted retroreflective measuring instrument is mounted on a vehicle and, under certain constraints, rapidly tests the road marking standards at vehicle speed, processing the results to obtain a set of measurements. These measurements are then compared to the standard values ​​to obtain indicators such as the indication error of the vehicle-mounted retroreflective measuring instrument, which are used to measure its performance. However, because the calibration work is conducted outdoors, measurement factors such as temperature, humidity, and ambient light are uncontrollable, and uncertainties introduced by factors such as road smoothness, vehicle handling, and driver characteristics are difficult to quantify, leading some experts to question the feasibility of this calibration method.

[0009] Therefore, after thoroughly analyzing the factors affecting the calibration results of the vehicle-mounted road marking retroreflection measuring instrument, the inventors of this invention propose an in-situ calibration method and device based on the relative velocity method that can be implemented indoors, which greatly reduces the introduction of uncertainty.

[0010] The existing calibration scheme is as follows:

[0011] (1) Environmental conditions

[0012] The ambient temperature is 4℃~50℃, the ambient humidity is not greater than 85%RH, and the ambient illuminance during the calibration process should include cases greater than 10000lx and less than 4000lx.

[0013] (2) Calibration equipment

[0014] A set of elongated strip-shaped marking standards, each 1000mm ± 10mm long and 150mm ± 10mm wide, with retroreflective luminance coefficients distributed in the range of (10~200) mcd·m -2 ·lx -1 (200~300)mcd·m -2 ·lx -1 (300~400)mcd·m -2 ·lx -1 (400~500)mcd·m -2 ·lx -1 (500~700)mcd·m -2 ·lx -1 Three out of five.

[0015] (3) Calibration method

[0016] On a dry and flat road surface, the measured values ​​of the vehicle-mounted road marking retroreflection measuring instrument were compared with reference values ​​by controlling variables such as speed and ambient light intensity. Different performance indicators were obtained, as detailed below:

[0017] a. Dynamic indication error: Place the pre-assigned (standard value) road marking standard on the road surface and drive at a speed of 50 km / h. At the same time, start the vehicle-mounted road marking retroreflection measuring instrument to measure the road marking standard. Measure each road marking standard 10 times and compare it with the standard value to obtain the dynamic indication error.

[0018] b. Error caused by detection speed: The vehicle-mounted road marking retroreflective measuring instrument was used to measure the road marking standard 10 times at speeds of 30km / h and 80km / h respectively. The error caused by detection speed was obtained based on the measurement results at different speeds.

[0019] c. Ambient light intensity influence error: Select time periods with illuminance greater than 10000 lx and illuminance less than 4000 lx respectively, start the vehicle-mounted road marking retroreflection measuring instrument to measure the road marking standard 10 times, and obtain the ambient light intensity influence error based on the measurement results under different illuminance conditions.

[0020] Existing calibration results are affected by factors such as environmental conditions, vehicle maneuverability, and driver characteristics, making it difficult to quantify the measurement uncertainty of relevant quantities. Specifically:

[0021] 1) Differences in factors such as road smoothness, vehicle maneuverability, and driver characteristics will randomly affect the measurement geometry of the vehicle-mounted road marking retroreflection measuring instrument. Furthermore, the measuring instrument itself lacks effective correction methods, which leads to random variations in the measurement results. As a result, the measurement uncertainty of the calibration results is difficult to quantify, thus weakening the calibration effect.

[0022] 2) Because the retroreflection value of the bar marking standard is non-uniform, and the vehicle-mounted retroreflection measuring instrument based on different measurement principles has different sampling ranges for the marking standard, this causes relative variation in the reference "standard value", making the calibration results of different instruments meaningless for comparison.

[0023] 3) The shape of the bar marking retroreflective standard limits the relative speed between it and the vehicle-mounted marking retroreflective measuring instrument, increasing the design difficulty of the relative displacement device;

[0024] 4) The value assignment method of the retroreflective standard for bar markings is a single-point measurement, and the assignment is not representative;

[0025] 5) Environmental conditions such as temperature, humidity, and illuminance will affect the measurement results in principle, and these factors are uncontrollable in outdoor environments, which can easily lead to the non-reproducibility of calibration results;

[0026] 6) The calibration process requires the vehicle to repeatedly drive on the same road segment, which can easily cause driver fatigue, and the repeated acceleration and deceleration process results in unnecessary energy waste. Summary of the Invention

[0027] The relative displacement device is constructed, changing the "instrument moves, marking standard remains stationary" to "instrument remains stationary, marking standard moves." The instrument's longitudinal tilt angle can be changed by rotating a single-sided helical structure to simulate the longitudinal forward and backward tilt of a vehicle. The marking standard's rotation is driven by a servo motor, which rotates the circular marking retroreflective standard, ensuring the tangential velocity at the center of the circular marking width reaches the corresponding test speed.

[0028] Design of a circular retroreflective standard for road markings. To achieve "in-situ" calibration of a vehicle-mounted retroreflective measuring instrument for road markings, it is necessary to realize the linear motion of the road marking retroreflective standard relative to the vehicle-mounted instrument, and the relative linear motion speed must reach 80 km / h. This relative motion is reproduced by the tangential velocity at a certain point on the rotational motion. Specifically, a circular retroreflective standard for road markings is designed. Given its diameter, the upper part of the standard can easily achieve the required linear velocity by designing the rotational speed.

[0029] The in-situ calibration device for a vehicle-mounted retroreflective pavement marking measuring instrument is characterized by:

[0030] It consists of a mounting platform for the instrument being calibrated, a rotating stage, and a retroreflective standard for the ring-shaped marking. The mounting platform allows the instrument to move forward, laterally, and in pitch, and includes a slide rail, base, telescopic rod, adjustable plate, and support rod. The rotating stage provides the corresponding rotation speed for the retroreflective standard for the ring-shaped marking, and includes a support, motor, bearing, and flange. The retroreflective standard for the ring-shaped marking is the carrier of the standard value of the retroreflective brightness coefficient, and includes a disc plate and coated glass microspheres.

[0031] The slide rail 1 can drive the entire device above the base 2 to move forward; the base 2 supports the telescopic rod 3 and the support rod 6 on its upper part, and is in rolling contact with the slide rail 1 on its lower part; the telescopic rod 3 changes its length by screwing in and out of the bolts, and further changes the pitch angle of the adjustable plate 4; the adjustable plate 4 is in rolling contact with the support rod 6 at one end, and is in free contact with the telescopic rod at the other end; the instrument to be calibrated 5 is placed on the adjustable plate 4; the support rod 6 is fixedly connected to the base 2; the servo motor 7 is connected to the support flange 10 through the bearing 9, the bearing 9 is set on the support 8, and the annular mark retroreflective standard 11 is set above the flange 10; the annular mark retroreflective standard 11 provides the retroreflective brightness coefficient standard value for the calibration of the vehicle-mounted mark retroreflective measuring instrument.

[0032] The base plate 21 of the circular marking plate is circular, with an angle scale of 0° to 360° at its geometric center. It connects to the rotating component 27 downwards and supports the primer layer 22 upwards. A coating layer 23 is applied on the primer layer 22. Glass microspheres or ceramic microspheres are bonded to the coating layer 23. Some of the glass microspheres or ceramic microspheres are embedded in the coating 23, also known as retroreflective elements. The assignment frame plate 25 has angle scale alignment holes and spot framing holes, which respectively serve to locate and frame the assignment area. The upper surface of the assignment frame plate 25 is coated with black body paint. The support plate 26 supports the assignment frame plate through four symmetrically arranged pillars, and the support plate 26 has a circular through hole in its center so that the rotating component 27 can pass through and connect to the circular marking plate.

[0033] The telescopic rod consists of a male end and a female end. The male end is fixedly connected to the base, and the female end is freely connected to the adjustable plate. The male end is at the bottom and the female end is at the top. The length of the telescopic rod is changed by rotating the female end in and out of the male end, which in turn causes one end of the adjustable plate to descend and rise.

[0034] Assigning values ​​to the retroreflective standard for ring-shaped road markings. Observing the rotating retroreflective standard for ring-shaped road markings from the perspective of a vehicle-mounted retroreflective measuring instrument, such as... Figure 1 The direction of the arrow in the middle line can only be approximated as the relative motion of the two objects if the movement is centered on a straight line perpendicular to the line of sight and passing through the center point of the ring, and the movement is directed towards a fan-shaped area of ​​a certain width towards the observer. For ease of calculation, a framing plate with a rectangular aperture is placed close to the retroreflective standard of the ring mark, defining the rectangular framing area, and ensuring that the light spot projected by the framing device completely covers this area. Figure 2 As shown, the retroreflective standard for the circular marking collects data once every 10° (or β°) of rotation. A total of 36 (or n, n = 360° / β°) data points are collected for a full rotation. The arithmetic mean is taken as the value assigned to the retroreflective standard for the circular marking by the assignment device.

[0035] The in-situ calibration device for the vehicle-mounted retroreflective pavement marking measuring instrument described in this invention mainly consists of a mounting platform for the instrument being calibrated, a rotating stage, and a ring-shaped retroreflective pavement marking standard. This in-situ calibration scheme for the vehicle-mounted retroreflective pavement marking measuring instrument is the first of its kind in this field. The mounting platform for the instrument being calibrated enables forward, lateral, and pitch movements and mainly consists of a slide rail, base, telescopic rod, adjustable plate, and support rod. The rotating stage provides the corresponding rotation speed for the ring-shaped retroreflective pavement marking standard and mainly consists of a support, motor, bearing, and flange. The ring-shaped retroreflective pavement marking standard is the core component of the in-situ calibration device and carries the standard value of the retroreflective brightness coefficient; it mainly consists of a disc plate and coated glass microspheres. The overall hardware connection diagram of the in-situ calibration device for the vehicle-mounted retroreflective pavement marking measuring instrument is shown below. Figure 3 , Figure 4 As shown. Attached Figure Description

[0036] Figure 1 Schematic diagram of assigning values ​​to the retroreflective standard for ring markings

[0037] Figure 2 Define the rectangular assignment area

[0038] Figure 3 Top view diagram of the hardware connection of the in-situ calibration device for the vehicle-mounted road marking retroreflection measuring instrument

[0039] Figure 4 Side view diagram of hardware connection for in-situ calibration device of vehicle-mounted road marking retroreflection measuring instrument

[0040] Figure 5 Top view of the hardware connection of the retroreflective standard for ring markings

[0041] Figure 6 Hardware connection cross-section of the retroreflective standard for ring markings

[0042] Figure 7 Flowchart of the manufacture of retroreflective standard for circular markings

[0043] 31-Optical control system; 32-Receiver; 33-Light source

[0044] 11-Ring Mark Retroreflective Standard; 35-Angle Platform; 36-Angle Controller

[0045] Figure 8 Assignment of retroreflective standard for ring marking

[0046] Figure 9 Flowchart for determining the travel of telescopic poles

[0047] Figure 10 Assembly Flowchart of In-situ Calibration Device for Vehicle-Mounted Road Marking Retroreflection Measuring Instrument

[0048] Figure 11 Calibration Workflow Diagram Detailed Implementation

[0049] Figure 3 , Figure 4In the system, slide rail 1 can drive the entire device above base 2 to move forward; base 2 supports the telescopic rod 3 and support rod 6, and is in rolling contact with slide rail 1; telescopic rod 3 changes its length by screwing in and out of bolts, and further changes the pitch angle of adjustable plate 4; adjustable plate 4 is in rolling contact with support rod 6 at one end and freely in contact with telescopic rod at the other end; the instrument to be calibrated 5 is placed on adjustable plate 4; support rod 6 is fixedly connected to base 2; servo motor 7 can rotate at a constant speed in the range of 200rpm to 700rpm and provides torque; servo motor 7 is connected to support flange 10 through bearing 9, bearing 9 is set on support 8, and an annular mark retroreflective standard 11 is set above flange 10; annular mark retroreflective standard 11 provides a standard value of retroreflective brightness coefficient for the calibration of vehicle-mounted mark retroreflective measuring instrument.

[0050] The instrument mounting platform and the rotating stage of the in-situ calibration device for the vehicle-mounted retroreflective marking measuring instrument described in this invention are independent structures, and the function is achieved by maintaining a specified geometric relationship. In addition, the retroreflective standard for ring markings and the rotating stage can be quickly disassembled and assembled through flanges.

[0051] The slide rail consists of two parallel linear guide rails with a length of 1500mm to 2000mm and an installation spacing of 200mm to 250mm. It has a slider, which is fixedly connected to the base. The slider can slide freely on the slide rail to drive the base and the structure above it to move forward.

[0052] The base supports the bottom of the telescopic rod and the support rod, and is fixedly connected to both.

[0053] The telescopic rod consists of a male end and a female end. The male end is fixedly connected to the base, and the female end is freely connected to the adjustable plate. The male end is at the bottom and the female end is at the top. The length of the telescopic rod is changed by rotating the female end in and out of the male end, which in turn causes one end of the adjustable plate to descend and rise.

[0054] One end of the adjustable plate is slidably connected to the support rod, and the other end is freely connected to the telescopic rod. When the length of the telescopic rod changes, it can drive the instrument being calibrated on it to change its pitch angle.

[0055] The servo motor uses pulse signals to control its speed, and can be adjusted from 200rpm to 700rpm. It is fixedly connected to the support through mounting holes.

[0056] The bracket is fixedly connected to the servo motor and provides support for the entire rotary table.

[0057] The bearing connects the output shaft of the servo motor to the flange, which can reduce friction.

[0058] The flange serves as a connection between the bearing and the retroreflective standard of the ring mark, preventing deformation caused by excessive local stress on the retroreflective standard of the ring mark.

[0059] The retroreflective standard for circular road markings mainly consists of a circular road marking plate, a value assignment frame plate, and a support plate. The circular road marking plate is the core component that enables the retroreflective function of the standard, and it mainly consists of a circular base plate, a primer layer, a paint layer, and glass or ceramic microspheres. The value assignment frame plate is a structural component that defines the value assignment area and also protects the circular road marking plate, limiting the light spot projected onto it to a rectangular area. It also has angle scale alignment holes for easy value assignment positioning. The support plate supports the value assignment frame plate via a support column, and its center has a circular through-hole through which a rotating component passes to drive the circular road marking plate to rotate.

[0060] Figure 5 , Figure 6 In the circular marking plate, the base plate 21 is circular, 2mm to 5mm thick, and has an angle scale of 0° to 360° at its geometric center. It connects downwards to the rotating component 27 and upwards to support the primer layer 22. The primer layer 22 is 0.2mm to 0.3mm thick and has good adhesion properties, allowing the coating layer 23 to bond more firmly to the base plate. The coating layer 23 is 0.8mm to 1.5mm thick, facilitating reliable bonding of glass microspheres or ceramic microspheres, and its interface with air has good light reflection properties. Microbeads 24, partially embedded in the coating 23, are the smallest unit for achieving retroreflection, also known as retroreflection elements; 25 is the assignment frame plate, which has angle scale alignment holes and spot framing holes, serving to locate and frame the assignment area respectively. In addition, its upper surface should be coated with an ideal black body paint so that the light retroreflected through its upper surface is almost zero; 26 is a support plate, which is supported by four symmetrically arranged pillars 28, and has a circular through hole in its center so that the rotating component can pass through and connect to the ring mark plate.

[0061] The circular base plate has a diameter of 800mm and a thickness of 2mm to 5mm. It is generally made of lightweight and high-strength materials such as aluminum alloy. Its geometric center has an angle scale of 0° to 360° to locate the value assignment area.

[0062] The primer layer has a circular planar structure with an outer circle of 800 mm and an inner circle of 500 mm; it is 0.2 mm to 0.3 mm thick and evenly coated; it has good adhesion properties so that the coating layer can be firmly bonded to the substrate.

[0063] The planar structure of the coating layer is also annular, with an outer circle of 800 mm and an inner circle of 500 mm; the thickness is 0.8 mm to 1.5 mm and the coating is uniform; the viscosity should be moderate under heating so that the glass or ceramic microspheres settle and partially embed themselves in the coating layer after cooling; the interface between the coating layer and the air should be smooth and have good light reflection properties.

[0064] Glass microspheres or ceramic microspheres are generally 20 to 50 mesh, and should not be too large or too small, so as not to affect their size when they settle and embed into the coating layer; glass microspheres or ceramic microspheres are the smallest unit to realize the retroreflective function of the retroreflective standard of the marking, also known as retroreflective element; the sphericity of glass microspheres or ceramic microspheres should not be less than 90%, and the refractive index should be between 1.5 and 1.9.

[0065] The assignment frame plate is a circular thin plate with a thickness not exceeding 1mm. The upper surface is coated with an ideal black body material to reduce the retroreflection performance of the area outside the beam frame hole on its upper surface. The assignment frame plate has a rectangular beam frame hole with a size of approximately 150mm*90mm to frame the assignment area, so that the beam size projected onto the circular marking plate is 150mm*90mm. The assignment frame plate has an angle scale alignment hole, which allows observation of the angle scale on the base plate to locate the assignment area.

[0066] The support plate is a circular plate with a thickness of 5mm to 8mm; the frame plate is supported by four symmetrically arranged pillars; a circular through hole in the center allows the rotating component to pass through and connect to the ring-shaped marking plate, thereby driving the rotation of the ring-shaped marking plate.

[0067] The rotating component is a transitional part connecting the rotating mechanism and the ring-shaped marking plate, and it plays a role in dispersing concentrated stress.

[0068] The upper end of the support should have threads and corresponding nuts to facilitate the adjustment of the height of the assignment frame plate. The adjustable distance is 0mm to 10mm to ensure that the vertical distance between the lower surface of the assignment frame plate and the upper surface of the circular marking plate is not greater than 1mm.

[0069] After clarifying the components and their relative positions of the in-situ calibration device for the vehicle-mounted road marking retroreflection measuring instrument, the following work mainly includes the fabrication and assignment of values ​​to the retroreflection standard for ring road markings and the determination of the travel of the telescopic rod. After that, the calibration work can be carried out using the in-situ calibration device for the vehicle-mounted road marking retroreflection measuring instrument.

[0070] The in-situ calibration device for the vehicle-mounted retroreflective marking measuring instrument of the present invention includes three annular retroreflective marking standards. The manufacturing process of each annular retroreflective marking standard is the same, as follows: Figure 7 As shown.

[0071] In the fabrication of the retroreflective standard for ring road markings, the first step involves prefabricating structural components such as a circular base plate, inner ring fixtures, outer ring fixtures, a value-assigning frame plate, and a support plate. The circular base plate is then sanded and powder-coated. The centering of the circular base plate, inner ring fixtures, and outer ring fixtures is then performed. The base plate is cleaned using a water bath and promptly dried to ensure it remains dry before being placed on a level platform. Using a brush or similar tool, primer is evenly applied to the annular area of ​​the base plate framed by the inner and outer ring fixtures. Simultaneously, the paint is melted and stored in a storage container, kept heated to maintain a temperature between 190℃ and 210℃. Stir constantly to ensure the coating is sufficiently uniform; 5-10 minutes after applying the primer, align the marking nozzle of the marking machine with the annular area of ​​the base plate, open the nozzle and control it at a certain opening degree. Simultaneously, rotate the base plate at a constant speed around its geometric center. Once the 360° rotation is complete, immediately close the nozzle; after the coating is applied, immediately use a spreader to evenly spread glass microspheres or ceramic microspheres to avoid insufficient settling due to delayed spreading. During spreading, keep the spreader stationary and rotate the base plate at a constant speed around its geometric center; after spreading, allow it to cool naturally for at least 1 hour; Figure 5 , Figure 6 As shown, assemble the circular marking plate, the assignment frame plate, and the support plate, and the circular marking retroreflective standard is completed.

[0072] After the retroreflective standard for ring markings is manufactured, it should be assigned a value before it is used for calibration.

[0073] First, the spatial relationships between the components in the assignment process are determined. The assignment of values ​​for the retroreflective standard for the ring mark uses a retroreflective measurement standard device, which consists of an optical control system, a light source, a receiver, a rotation controller, and a rotation platform. The spatial relationships between these components are illustrated below. Figure 8 As shown. The retroreflective standard for the ring mark is placed on the corner platform. The light spot projected by the light source of the retroreflective measurement standard device should completely cover the light spot frame hole on the assignment frame plate, and the direction of the projected light should be parallel to the long side of the light spot frame hole.

[0074] The next step is the assignment process. First, turn on the light source of the retroreflection measurement standard device and preheat it. Adjust the aperture size so that the light spot projected onto the assignment frame plate completely covers the light spot frame hole. After the light source stabilizes, rotate the ring mark plate of the ring mark retroreflection standard so that the 0° mark on the ring mark plate is aligned with the center mark of the light spot frame hole length. Read the retroreflection brightness coefficient value of the ring mark retroreflection standard at this time and record it as n1. Then, rotate the ring mark plate clockwise by 10° (or β°) so that the 10° (or β°) mark on the ring mark plate is aligned with the center mark of the light spot frame hole length. Read the retroreflection brightness coefficient value of the ring mark retroreflection standard again and record it as n2. Repeat this operation until the ring mark plate is rotated 360°, and read a total of 36 (or n, n = 360° / β°, the same below) retroreflection brightness coefficient values.

[0075] Finally, the standard value of the retroreflective standard for ring road markings is determined. The 36 (or n) values ​​read above are generally different, representing the non-uniformity of the retroreflective brightness coefficient values ​​of the retroreflective standard for ring road markings. Therefore, the arithmetic mean of the 36 (or n) retroreflective brightness coefficient values ​​is taken as the standard value of the retroreflective standard for ring road markings.

[0076] The determination of the telescopic boom stroke can be divided into two steps according to the process: acquiring the vehicle pitch angle and restoring the vehicle pitch angle.

[0077] In the process of collecting vehicle pitch angle data, attitude sensors are attached to the mounting plane of the vehicle-mounted road marking retroreflective measuring instrument on different vehicles. The vehicles are then driven on standard road sections at different speeds to collect pitch angle variation data of different vehicles at different speeds. Based on the probability distribution of the data, information such as the pitch angle variation range is determined, which is the pitch angle range of the vehicle-mounted road marking retroreflective measuring instrument under driving conditions. For the convenience of calibration, typical test angle sets such as 0°, 1°, 2°, and 3° are agreed upon.

[0078] The in-situ calibration device for the vehicle-mounted road marking retroreflection measuring instrument changes the tilt angle of the adjustable plate by adjusting the length of the telescopic rod, so that the tilt angle meets the agreed typical test angle. Then, based on the trigonometric relationship, the travel of the telescopic rod corresponding to the set of typical test angles is determined.

[0079] At this point, the fabrication and calibration of the retroreflective standard for the ring road markings are complete, the travel of the telescopic pole has been determined, and the assembly process of the in-situ calibration device for the vehicle-mounted retroreflective measuring instrument is as follows: Figure 10 As shown.

[0080] The assembly of each component of the in-situ calibration device for the vehicle-mounted retroreflective road marking measuring instrument should follow the installation sequence from bottom to top. Each component should be installed firmly and reliably. The mounting platform and rotating table of the instrument being calibrated should be installed independently, and then the relative positional relationship between the two should be determined.

[0081] During the installation of the instrument mounting platform, the slide rail should be installed horizontally to ensure that the entire mounting platform is in a horizontal state. The base is slidably connected to the slide rail by a slider fixedly installed below it. The slider is locked during operation to ensure that there is no relative displacement between the slide rail and the base. The lower ends of the telescopic rod and support rod are fixedly connected to the upper surface of the base. One end of the adjustable plate is slidably connected to the support rod, and the other end is freely connected to the telescopic rod.

[0082] During the installation of the rotary table, the support should be placed horizontally and stably, with leveling feet at the bottom. The servo motor is directly fixed to the support through the mounting holes, and its output shaft passes through the center of the output shaft hole on the upper surface of the support. The inner surface of the bearing is nested with the output shaft of the servo motor, and the outer surface of the bearing is interference-fitted with the inner side of the output shaft hole on the upper surface of the support to reduce vibration and friction during motor rotation. One end of the flange is connected to the keyway of the motor output shaft, and the other end is connected to the positioning mounting hole of the ring mark retroreflective standard, serving as a transition to avoid stress concentration and deformation caused by direct connection of the servo motor output shaft to the ring mark retroreflective standard. The ring mark retroreflective standard is connected to the flange. Since it is generally a thin plate structure, if necessary, additional reinforcing ribs should be added to its bottom surface to protect its flat shape.

[0083] Thus, the instrument mounting platform and the rotating stage were installed independently. The relative positions of the two were adjusted so that the tangent of the center extension line of the adjustable plate and the center line of the circular marking coincided in the direction of the center extension line of the adjustable plate. The in-situ calibration device of the vehicle-mounted retroreflective marking measuring instrument was thus completed.

[0084] First, place the vehicle-mounted retroreflective pavement marking measuring instrument to be calibrated on the adjustable plate, and adjust the telescopic rod to make it horizontal, i.e., 0°. Then, power on and preheat the instrument, and activate its measurement mode. Based on the spatial distribution of the projected light spot of the instrument in measurement mode, adjust the position of the mounting platform relative to the rotary table so that the projected light spot covers the elongated hole in the assignment frame plate. Figure 3 As shown; the following steps will be performed in sequence according to the calibration parameters:

[0085] (1) Dynamic indication error. Turn on the dynamic measurement mode of the vehicle-mounted retroreflective measuring instrument being calibrated, and simultaneously turn on the servo motor of the rotary table, adjusting its speed so that the tangential velocity at the center point of the ring mark width reaches V km / h (e.g., V = 50); turn on the data acquisition function of the vehicle-mounted retroreflective measuring instrument being calibrated, and continuously acquire m sets of measurement data; take the arithmetic mean of the m sets of measurement data as the measured value, and compare it with the standard value of the corresponding ring mark retroreflective standard to obtain the indication error; replace the ring mark retroreflective standard with a different standard value, repeat the above steps, and obtain the indication error of the corresponding ring mark retroreflective standard again; repeat this process until the measurement of x ring mark retroreflective standards is completed, and take the maximum value of x indication errors as the dynamic indication error.

[0086] (2) Error in pitch angle variation. Adjust the telescopic rod to keep the pitch angle of the adjustable plate at 1t°, 2t°, and 3t° successively, and at the same time turn on the dynamic measurement mode of the vehicle-mounted road marking retroreflection measuring instrument being calibrated; at each pitch angle, measure any circular road marking retroreflection standard, collect m sets of measurement data, and take the arithmetic mean as the measurement value at different pitch angles; take the range of the measurement values ​​at different pitch angles as the error in pitch angle variation.

[0087] (3) Lateral position variation indication error. Adjust the telescopic rod to restore the adjustable plate to 0°; with the initial position as the center, move the entire instrument mounting platform to the left and right by 1 mm. In dynamic measurement mode, collect m sets of measurement data and take the arithmetic mean as the measurement value at different lateral positions; calculate the difference between the difference and the measurement value at the center position, and take the larger one as the lateral position variation indication error.

[0088] Based on the specifications and the above calibration results, the performance of the calibrated vehicle-mounted road marking retroreflective measuring instrument is comprehensively evaluated.

[0089] 6.1 The in-situ calibration method and device for the vehicle-mounted retroreflective road marking measuring instrument described in this invention realizes controllable calibration geometry conditions, reducing the uncertainty introduced by factors such as road unevenness, vehicle handling instability and different driver driving characteristics;

[0090] 6.2 In-situ calibration of the vehicle-mounted retroreflective marking instrument is achieved by rotating the ring-shaped marking plate inside the retroreflective marking standard. The tangential motion of a certain area during the rotation can approximately reproduce the relative linear motion between the vehicle-mounted retroreflective marking instrument being calibrated and the ring-shaped marking plate. Compared with the construction of a linear motion device for the strip marking plate, this method is more economical and convenient. By relying on different rotation speeds of the rotary table to simulate different driving speeds of the vehicle, repeated driving tests are avoided, simplifying the calibration workflow and improving calibration efficiency.

[0091] 6.3 It replaces the construction and daily maintenance of the test standard road, requiring only the construction of a simple in-situ calibration device, thus reducing the cost of calibration work;

[0092] The method for assigning the standard value of the 6.4 ring mark retroreflective standard makes it closer to the true value, reduces the influence of uniformity on the calibration work, and makes the calibration results more reliable.

[0093] 6.5 The calibration environment is moved from outdoors to indoors, making environmental conditions such as temperature, humidity, and illuminance controllable, and the calibration work is no longer limited by severe weather.

[0094] The manufacturing process and technology of the retroreflective standard for 6.6 ring markings can effectively ensure its quality and reduce the cost of repeated production;

[0095] The setting of rectangular spot framing holes on the 6.7 assignment framing plate can reduce the workload of data calculation and processing and improve the efficiency of calibration work.

[0096] The in-situ calibration scheme for vehicle-mounted road marking retroreflection measuring instruments and similar products, as well as the structural form and value assignment method of the ring road marking retroreflection standard, are detailed below:

[0097] (1) The calibration method based on the in-situ calibration device of the vehicle-mounted retroreflection measuring instrument, namely the entire workflow of testing the dynamic indication error, pitch angle variation indication error, and lateral position variation indication error of the relevant products.

[0098] (2) The overall design scheme of the in-situ calibration device of the vehicle-mounted retroreflective marking measuring instrument, including the design method of the instrument mounting platform and the rotating table, and the determination of the relative positions between the two;

[0099] (3) Use a rectangular spot to frame the spot projection area and perform value measurement. Rotate the ring mark plate at equal angles (β°). Take the arithmetic mean of the 36 (or n, n = 360° / β°) retroreflection brightness coefficient values ​​obtained by rotating the ring mark plate one revolution. Use this as the method for assigning the standard value of the retroreflection standard of the ring mark.

[0100] (4) The in-situ calibration device changes the motion relationship so that the instrument being calibrated remains stationary while the standard marker moves, thus reproducing the calibration work of the vehicle at the driving speed.

[0101] (5) The workflow and method of applying primer, marking coating, and spreading glass microbeads or ceramic microbeads on the circular marking board;

[0102] (6) A method for determining the travel of the telescopic boom by collecting the vehicle pitch angle and restoring the vehicle pitch angle.

Claims

1. A vehicle-mounted retroreflective marking measuring instrument in-situ calibration device, characterized in that: It consists of a mounting platform for the instrument being calibrated, a rotating stage, and a retroreflective standard for the ring-shaped marking. The mounting platform allows the instrument to move forward, laterally, and in pitch, and includes a slide rail, base, telescopic rod, adjustable plate, and support rod. The rotating stage provides the corresponding rotation speed for the retroreflective standard for the ring-shaped marking, and includes a support, motor, bearing, and flange. The retroreflective standard for the ring-shaped marking is the carrier of the standard value of the retroreflective brightness coefficient, and includes a disc plate and coated glass microspheres. The slide rail can drive the entire device on the base to move forward; the base supports the telescopic rod and support rod structure above, while its lower part is in rolling contact with the slide rail; the telescopic rod changes its length by screwing in and out the bolts, and further changes the pitch angle of the adjustable plate; one end of the adjustable plate is in rolling contact with the support rod, and the other end is in free contact with the telescopic rod; the instrument to be calibrated is placed on the adjustable plate; the support rod is fixedly connected to the base; the servo motor is connected to the support flange through the bearing, the bearing is set on the support, and a ring-shaped retroreflective standard is set above the flange; the ring-shaped retroreflective standard provides a standard value of retroreflective brightness coefficient for the calibration of the vehicle-mounted retroreflective measuring instrument; The base plate of the circular road marking plate is circular, with an angle scale of 0°~360° at its geometric center. It connects to the rotating component downwards and supports the primer layer upwards. A coating layer is applied on the primer layer. Glass microspheres or ceramic microspheres are bonded to the coating layer. Some of the glass microspheres or ceramic microspheres are embedded in the coating layer, also known as retroreflective elements. The assignment frame plate has angle scale alignment holes and spot framing holes, which respectively serve to locate and frame the assignment area. The upper surface of the assignment frame plate is coated with black body paint. The support plate supports the assignment frame plate through four symmetrically arranged pillars, and the support plate has a circular through hole in its center so that the rotating component can pass through and connect to the circular road marking plate.

2. The apparatus according to claim 1, characterized in that: The telescopic rod consists of a male end and a female end. The male end is fixedly connected to the base, and the female end is freely connected to the adjustable plate. The male end is at the bottom and the female end is at the top. The length of the telescopic rod is changed by rotating the female end in and out of the male end, which in turn causes one end of the adjustable plate to descend and rise.

3. The method using the apparatus as described in claim 1, characterized in that: After the retroreflective standard for ring marks is manufactured, it should be assigned a value before it is used for calibration. First, determine the spatial relationship between the components in the assignment process; the assignment of the retroreflective standard for the ring mark uses a retroreflective measurement standard device. The retroreflective standard for the ring mark is placed on the corner platform. The light spot projected by the light source of the retroreflective measurement standard device should completely cover the light spot frame hole on the assignment frame plate, and the direction of the projected light is parallel to the long side of the light spot frame hole. The next step is the assignment process. First, turn on the light source of the retroreflection measurement standard device and preheat it. Adjust the aperture size so that the light spot projected onto the assignment frame plate completely covers the light spot frame hole. Rotate the annular mark plate of the annular mark retroreflection standard so that the 0° mark on the annular mark plate is aligned with the center mark of the length of the light spot frame hole. Read the retroreflection brightness coefficient value of the annular mark retroreflection standard at this time and record it as n1. Then rotate the annular mark plate clockwise by β° so that the β° mark on the annular mark plate is aligned with the center mark of the length of the light spot frame hole. Read the retroreflection brightness coefficient value of the annular mark retroreflection standard again and record it as n2. Repeat this operation until the annular mark plate is rotated 360°, and a total of n retroreflection brightness coefficient values ​​are read, n = 360° / β°. Finally, the standard value of the retroreflective standard for ring road markings is determined; the arithmetic mean of n retroreflective brightness coefficients is taken as the standard value of the retroreflective standard for ring road markings.

4. The method of using the apparatus as described in claim 1, characterized in that: During the installation of the instrument mounting platform, the slide rail should be installed horizontally to ensure that the entire instrument mounting platform is in a horizontal state; the base is slidably connected to the slide rail by a slider fixedly installed below it, and the slider is locked during operation to ensure that there is no relative displacement between the slide rail and the base; the lower ends of the telescopic rod and the support rod are fixedly connected to the upper surface of the base; one end of the adjustable plate is slidably connected to the support rod, and the other end is freely connected to the telescopic rod. During the installation of the rotary table, the support should be placed horizontally and stably, with leveling feet at the bottom. The servo motor is directly fixed to the support through the mounting holes, and its output shaft passes through the center of the output shaft hole on the upper surface of the support. The inner surface of the bearing is nested with the output shaft of the servo motor, and the outer surface of the bearing is interference-fitted with the inner side of the output shaft hole on the upper surface of the support to reduce vibration and friction during motor rotation. One end of the flange is connected to the keyway of the motor output shaft, and the other end is connected to the positioning mounting hole of the ring mark retroreflective standard, serving as a transition to avoid stress concentration and deformation caused by direct connection of the servo motor output shaft to the ring mark retroreflective standard. The ring mark retroreflective standard is connected to the flange. After the instrument mounting platform and rotary table are installed independently, adjust their relative positions so that the tangent of the center extension line of the adjustable plate matches the tangent of the center line of the circular marking in the direction of the center extension line of the adjustable plate. The in-situ calibration device of the vehicle-mounted marking retroreflection measuring instrument is then completed.

5. The method of using the apparatus as described in claim 1, characterized in that: First, place the vehicle-mounted road marking retroreflection measuring instrument to be calibrated on the adjustable plate and adjust the telescopic rod to make it horizontal, i.e., 0°. Then, power on and preheat the vehicle-mounted road marking retroreflection measuring instrument to be calibrated and turn on its measurement mode. According to the spatial distribution of the projected light spot of the vehicle-mounted road marking retroreflection measuring instrument to be calibrated in the measurement mode, adjust the positional relationship between the mounting platform of the instrument to be calibrated and the rotary table so that the projected light spot covers the elongated hole of the assignment frame plate. (1) Dynamic indication error; turn on the dynamic measurement mode of the vehicle-mounted road marking retroreflection measuring instrument to be calibrated, and at the same time turn on the servo motor of the rotary table, adjust its speed so that the tangential speed at the center point of the ring road marking width reaches Vkm / h, V=50; turn on the data acquisition function of the vehicle-mounted road marking retroreflection measuring instrument to be calibrated, and continuously acquire m sets of measurement data; take the arithmetic mean of the m sets of measurement data as the measured value, and compare it with the standard value of the corresponding ring road marking retroreflection standard to obtain the indication error; replace the ring road marking retroreflection standard with a different standard value, repeat the above steps, and obtain the indication error of the corresponding ring road marking retroreflection standard again; repeat this process until the measurement of x ring road marking retroreflection standards is completed, and take the maximum value of x indication errors as the dynamic indication error; (2) Error of pitch angle variation; Adjust the telescopic rod to keep the pitch angle of the adjustable plate at 1t°, 2t°, and 3t° respectively, and at the same time turn on the dynamic measurement mode of the vehicle-mounted road marking retroreflection measuring instrument being calibrated; Under each pitch angle state, measure any circular road marking retroreflection standard, collect m sets of measurement data, and take the arithmetic mean as the measurement value under different pitch angles; Take the range of the measurement values ​​under different pitch angles as the error of pitch angle variation. (3) Lateral position variation indication error; Adjust the telescopic rod to restore the adjustable plate to 0°; With the initial position as the center, move the entire instrument mounting platform to the left and right by 1 mm. In dynamic measurement mode, collect m sets of measurement data and take the arithmetic average as the measurement value at different lateral positions; Subtract the measurement value from the center position respectively, and take the larger one as the lateral position variation indication error.

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