Laser vehicle type detection and calibration device and calibration method

Abstract

The present application belongs to the technical field of intelligent vehicle information collection devices and methods, and discloses a laser vehicle model detection and calibration device and calibration method. The laser vehicle model detection and calibration device includes a straight and retractable crossbar, a plurality of groups of legs that can be retracted up and down are connected below the crossbar, a level ruler is fixedly installed in the middle of the crossbar, one end of the crossbar is provided with a laser indicator perpendicular to the crossbar, and another crossbar with an angular scale that can rotate clockwise and counterclockwise is provided below the crossbar. The present invention uses an adjustable calibration device suitable for uneven roads and is easy to operate; the height and spacing of the laser scanner are calibrated with high precision; the error caused by the displacement of the equipment in the later stage can be eliminated by calibration, and there is no need to use an aerial work vehicle for secondary position adjustment, saving manpower and material resources.

Description

Technical Field

[0001] The present application belongs to the technical field of intelligent vehicle information collection devices and methods, and specifically relates to a laser vehicle model detection and calibration device and calibration method. Background Art

[0002] Vehicle type detection is one of the elements of traffic information collection. Laser scanning is the most widely used in vehicle type detection systems due to its advantages of high precision, fast scanning speed, and few interference factors. The principle of laser scanning is mainly that the laser scanner uses a modulated laser that is harmless to the human eye to scan the entire vehicle, and collects the laser reflected from various positions of the vehicle to measure the distance to calculate the vehicle appearance data to achieve the purpose of vehicle type detection. The calculation of data requires the road surface under the laser scanner as a reference point, and the distance between the laser scanner and the road surface is calculated as a reference value. Then, the distance between the vehicle and the laser scanner is subtracted and the vehicle appearance dimensions can be obtained through trigonometric calculation. This places high demands on the installation accuracy of the laser scanner. If the laser scanner is not perpendicular to the ground or the scanning harness area is not perpendicular to the detection lane, the detection results will be inaccurate.

[0003] The levelness of the road surface will also affect the detection data. When a vehicle passes through an uneven road surface under the laser scanner, the height and width of the detected vehicle will be inaccurate. As the equipment is set up for a longer time, the vibration caused by heavy vehicles passing by or the displacement of the road surface and the laser scanner mounting column caused by geological movement will also cause errors in the detection.

[0004] The laser scanner is installed at a height of more than 6 meters above the inspection lane, which requires road closure and the assistance of an aerial work vehicle. Both installation and subsequent calibration are time-consuming and laborious. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of this application is to provide a laser vehicle model detection and calibration device and calibration method. When errors occur after installation and use for a period of time, the device and method can be used to calibrate the vehicle model detection system to make the detection results accurate.

[0006] To achieve the above objectives, this application adopts the following technical solutions:

[0007] A laser vehicle type detection and calibration device comprises a straight retractable crossbar, a plurality of groups of legs that can be retracted up and down are connected below the crossbar, a level ruler is fixedly installed in the middle of the crossbar, one end of the crossbar is provided with a laser indicator perpendicular to the crossbar, and another crossbar with an angular scale that can rotate clockwise and counterclockwise is provided below the crossbar.

[0008] Preferably, there is another cross bar with an angular scale below the cross bar, which can rotate clockwise and counterclockwise by a maximum of 20 degrees.

[0009] Preferably, the support foot has scales and threads, and the support foot is connected to the cross bar through threads.

[0010] When the laser vehicle type detection and calibration device is installed for the first time, it includes height and width detection calibration and length detection calibration, wherein the width and height detection calibration specifically includes the following steps:

[0011] 11) Calibrate the verticality between the laser scanner laser beam scanning area and the detection lane top view direction

[0012] The calibration device is arranged directly below the laser scanner, and the light emitted by the laser pointer is perpendicular to the crossbar of the calibration device. The laser pointer on the calibration device is used to illuminate the laser scanner to determine whether the calibration device is directly below the laser scanner.

[0013] Adjust the calibration device to be perpendicular to the detection lane in the top view direction, adjust the crossbar of the calibration device to the lane width, and use a level ruler to adjust each leg of the calibration device so that the crossbar is horizontal and each leg is stably in contact with the ground;

[0014] Turn on the laser scanner and set the laser beam scanning angle so that the starting laser beam can reach the edge of one side of the lane and the ending laser beam can reach the edge of the other side of the lane; check the distance detected by each laser beam of the laser scanner within the set scanning angle. The correct distance value is a trend from small to large. Ensure that within the set scanning angle, the laser scanner's laser beams are all scanned onto the crossbar of the calibration device;

[0015] 12) Calibrate the vertical laser beam in the direction of the laser scanner

[0016] After the calibration in step 11), the laser beam with the shortest distance measured should be perpendicular to the calibration device, and this laser beam is set as the starting laser beam, which will be used as a necessary condition for calculating the width and height of the vehicle in the later stage of vehicle type detection;

[0017] 13) Calibrate the laser scanner horizontal distance

[0018] Adjust the crossbar of the calibration device so that the starting beams of the two laser scanners just hit the corresponding edges of the crossbar;

[0019] The length of the crossbar of the calibration device at this time can be calculated using the trigonometric function l1'*sinα', that is, the horizontal distance between the two laser scanners, where α' is the angle between the edge laser beam and the starting laser beam, and l1' refers to the distance from the laser scanner to the diagonally opposite edge of the crossbar measured by the edge laser beam;

[0020] 14) Width and height detection

[0021] When calculating the width and height of the vehicle, the vertical height H1 of the laser scanner from the ground must be measured first, and the distance l1 from the roof to the laser scanner is measured by a laser beam that forms an angle α with the starting laser beam. The trigonometric function l1*Sinα is used to obtain the horizontal distance w1 from the roof to the laser scanner, and l1*Cosα is used to obtain the height h1 from the roof to the laser scanner. The same method is used to obtain the vertical height H2 of the other laser scanner from the ground, the horizontal distance w2 from the roof to the laser scanner, and the height h2 from the roof to the laser scanner. Due to different cargoes loaded on the vehicle, the highest point and the widest point are not necessarily at the two vertices of the vehicle. It is necessary to calculate w1, w2 and h1, h2 of each laser beam within the starting and ending angles of the two laser scanners, and take their minimum value as the basis for the final calculation.

[0022] The actual width of the vehicle is D-w1-w2, where D is the horizontal distance between the two laser scanners;

[0023] The actual height of the vehicle is H1-h1 on one side and H2-h2 on the other side.

[0024] Furthermore, the actual height of the vehicle takes the maximum value in the super-height detection application and takes the average value in the vehicle type identification.

[0025] The length detection calibration specifically includes the following steps:

[0026] 21) Calibrate the horizontality between the laser scanner laser beam scanning area and the detection lane in the top view direction

[0027] The length detection uses a laser scanner. The calibration device is placed directly below the laser scanner. The calibration device is parallel to the detection lane in the top view direction. The crossbar of the calibration device is adjusted to the longest. The legs of the calibration device are adjusted to make the crossbar horizontal and the legs stably contact the ground.

[0028] Turn on the laser scanner and set the laser beam scanning angle so that the initial laser beam can reach the edges of both sides of the crossbar of the calibration device; and ensure that within the set scanning angle, the laser beam of the laser scanner is fully scanned onto the crossbar of the calibration device;

[0029] 22) Length detection

[0030] The crossbar length c can be calculated by the distance a measured by the starting laser beam, the distance b measured by the ending laser beam, and the angle γ between the two laser beams, using the formula: c 2 =a 2 +b 2 -2*a*b*Cosγ.

[0031] Preferably, in steps 11) and 21), the feet of the calibration device are adjusted so that the top surface of the crossbar is 500 mm above the ground.

[0032] Preferably, in steps 11) and 12), the laser scanners on both sides need to be calibrated separately.

[0033] Preferably, in step 13), if the ending laser beam of the laser scanner is emitted outside the calibration device, each laser beam should be searched forward from the ending laser beam to find a laser beam whose measured distance meets the value of H'÷Sinα, where H' is the height of the laser scanner from the calibration device, α is the angle between each laser beam and the starting beam, and the angle between each laser beam and the starting beam is a fixed value, which can be obtained by multiplying the difference in laser beam serial numbers by the fixed angle. At this time, this laser beam is used as the ending laser beam.

[0034] Furthermore, in step 13), the length of the crossbar of the calibration device is measured with a tape measure to verify the calculation result and confirm that the edge laser beam is accurately found.

[0035] Further, in step 13), the horizontal distance D between the two laser scanners is calculated again using the same method for another laser scanner. If the error between the two calculation results is less than 2.5 cm, it means that the calibration is successful, otherwise recalibration is required; the average of the two horizontal distances is calculated as the final horizontal distance D between the two laser scanners.

[0036] Furthermore, in step 22), a tape measure is used to measure the length of the current crossbar of the calibration device and compare it with the calculated crossbar length. If the error of the calculated result is less than 2.5 cm, it means that the calibration is successful. Otherwise, it means that the laser beam scanning area and the overhead direction of the detection lane are not level enough, and the crossbar of the calibration device needs to be narrowed to recalibrate the level.

[0037] Furthermore, when detection errors occur after the laser scanner has been installed and used for a period of time, the width and height detection calibration is performed as follows:

[0038] The laser scanners on both sides need to be calibrated separately. Place the calibration device directly below the laser scanner. Use the high-brightness laser pointer on the calibration device to illuminate the laser scanner to determine whether the calibration device is directly below the laser scanner. The calibration device is perpendicular to the detection lane in the top-down direction. Adjust the crossbar of the calibration device to the lane width. Use the level ruler to adjust each leg of the calibration device so that the crossbar is horizontal and each leg is stably in contact with the ground.

[0039] Turn on the laser scanner and set the laser beam scanning angle so that the starting laser beam can reach the edge of one side of the lane and the ending laser beam can reach the edge of the other side of the lane;

[0040] Check the distance detected by each laser beam of the laser scanner within the set scanning angle. The correct distance value is a trend from small to large. Ensure that within the set scanning angle, the laser beam of the laser scanner scans all the laser beams on the calibration device crossbar. If the laser beam does not scan all the crossbar of the calibration device but scans the ground, you need to rotate the crossbar with the angle scale out of the calibration device, check the distance detected by each laser beam of the laser scanner within the set scanning angle, adjust the rotation angle of the crossbar with the angle scale, find the vertical deviation between the laser scanner and the detection lane in the top-view direction, and record the current deviation angle θ through the angle scale.

[0041] Continue to calibrate the vertical laser beam in the front view direction of the laser scanner. After the previous calibration, the laser beam with the shortest distance measured should be perpendicular to the calibration device. Set this laser beam as the starting laser beam.

[0042] Then calibrate the horizontal distance of the laser scanner, rotate the calibration device as a whole to the deflection direction of the laser beam scanning area, and then adjust the crossbar to the edge of the lane, and calculate the horizontal distance D' between the two laser scanners using the trigonometric function l1*sinα*cosθ; use the same method to calculate the other laser scan again. If the error between the two calculation results and the tape measure measurement result is less than 2.5cm, it means that the calibration is successful. Otherwise, it means that the angle θ is inaccurate and needs to be recalibrated.

[0043] When calculating the width and height of the vehicle, the vertical height H1 of the laser scanner from the ground must be measured first, and the distance l1 from the roof to the laser scanner is measured by a laser beam that forms an angle α with the starting laser beam. The trigonometric function l1*Sinα*cosθ is used to obtain the horizontal distance w1' from the roof to the laser scanner, and l1*Cosα*cosθ is used to obtain the height h1 from the roof to the laser scanner. The same method is used to obtain the vertical height H2 of the other laser scanner from the ground, the horizontal distance w2' from the roof to the laser scanner, and the height h2 from the roof to the laser scanner. Due to different cargoes loaded on the vehicle, the highest point and the widest point are not necessarily at the two vertices of the vehicle. It is necessary to calculate w1', w2' and h1, h2 of each laser beam within the starting and ending angles of the two laser scanners, and take their minimum value as the basis for the final calculation.

[0044] The actual width of the vehicle is D'-w1'-w2';

[0045] The actual height of the vehicle is H1-h1 on one side and H2-h2 on the other side;

[0046] The length detection calibration is carried out as follows:

[0047] Place the calibration device directly below the laser scanner, parallel to the detection lane in the top view direction, extend the crossbar of the calibration device to the maximum, and adjust the legs of the calibration device to make the crossbar horizontal and the legs stably contact the ground;

[0048] Turn on the laser scanner and set the laser beam scanning angle so that the initial laser beam can reach the edges of both sides of the crossbar of the calibration device;

[0049] Check the distance detected by each laser beam of the laser scanner within the set scanning angle. The correct distance value is a trend from large to small and then to large. If the laser beam does not scan all of the crossbar of the calibration device, but scans the ground, it is necessary to rotate the crossbar with the angle scale out of the calibration device, check the distance detected by each laser beam of the laser scanner within the set scanning angle, and adjust the rotation angle of the crossbar with the angle scale so that the distance value detected by each laser beam is a trend from large to small and then to large. This indicates that the parallelism deviation between the laser scanner and the detection lane in the top-view direction has been found, and the current deviation angle ω is recorded through the angle scale.

[0050] The crossbar length c can be calculated by the distance a measured by the starting laser beam, the distance b measured by the ending laser beam, and the angle γ between the two laser beams, using the formula: c 2 =(a 2 +b 2 -2*a*b*Cosγ)cosω*.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The use of an adjustable calibration device is suitable for uneven roads and is easy to operate;

[0053] (2) Calibrate the height and spacing of the laser scanner with high accuracy;

[0054] (3) The error caused by displacement of the equipment in the later stage can be eliminated through calibration, without the need to use an aerial work vehicle for secondary position adjustment, thus saving manpower and material resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0056] Figure 1 This is a schematic diagram of the structure of the laser vehicle model detection and calibration device;

[0057] Figure 2 This is a schematic diagram of width and height detection calibration;

[0058] Figure 3When calibrating for width and height detection, the distance value curve diagram detected by each laser beam within the set scanning angle of the laser scanner;

[0059] Figure 4 A schematic diagram of a vertical laser beam in the normal viewing direction of a calibrated laser scanner;

[0060] Figure 5 Schematic diagram of horizontal distance for calibrating laser scanner;

[0061] Figure 6 It is a schematic diagram of height and width detection of a vehicle;

[0062] Figure 7 This is a schematic diagram of length detection calibration;

[0063] Figure 8 When calibrating the length, set the laser beam scanning angle so that the starting laser beam can reach both sides of the crossbar of the calibration device;

[0064] Fig. 9 When calibrating for length detection, the laser scanner shows the distance values ​​detected by each laser beam within the set scanning angle;

[0065] Fig.10 Schematic diagram of a deviated laser beam scanning area and a correct laser beam scanning area;

[0066] Fig.11 The correct distance value curve of the laser beam when calibrating the length detection;

[0067] Fig.12 It is a schematic diagram of length detection;

[0068] Fig.13 This is a schematic diagram of width and height detection calibration;

[0069] Fig.14 This is a schematic diagram of length detection calibration.

[0070] Markings in the figure: 1-calibration device, 2-laser scanner, 3-laser scanner 1, 4-laser scanner 2, 5-crossbar, 6-support foot, 7-laser pointer, 8-level ruler, 9-crossbar with angle scale. DETAILED DESCRIPTION

[0071] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0072] A laser vehicle type detection and calibration device comprises a straight and retractable crossbar, a plurality of groups of legs that can be retracted up and down are connected below the crossbar, a level ruler 8 is fixedly installed in the middle of the crossbar, one end of the crossbar is provided with a high-brightness laser indicator 7 perpendicular to the crossbar, for example, a laser indicator with a product model of LHGD-22100-300mw can be selected, and another crossbar 9 with an angle scale that can rotate clockwise / counterclockwise up to 20 degrees is provided below the crossbar, and the crossbar with the angle scale is usually stored below the upper crossbar, such as Figure 1 The support legs are provided with scales and threads, and the support legs are connected to the crossbar via threads.

[0073] When installing the laser vehicle type detection and calibration device for the first time, follow the steps below:

[0074] Width and height detection calibration:

[0075] 11) Calibrate the verticality between the laser scanner laser beam scanning area and the detection lane top view direction

[0076] The correct laser beam scanning area should be perpendicular to the detection lane in the top-down direction, so that the width obtained by the laser beam scanning when the vehicle passes under the laser scanner is the actual width of the vehicle. Otherwise, the measured width will increase, such as Figure 2 As shown;

[0077] The laser scanners on both sides need to be calibrated separately. The calibration device is placed directly below the laser scanner. The light emitted by the laser pointer is perpendicular to the crossbar of the calibration device. The laser pointer on the calibration device is used to illuminate the laser scanner to determine whether the calibration device is directly below the laser scanner.

[0078] Adjust the calibration device to be perpendicular to the detection lane in the top view direction, extend the crossbar of the calibration device to the lane width, and use a level ruler to adjust each leg of the calibration device so that the crossbar is horizontal and each leg is stably in contact with the ground. The height of the top surface of the crossbar from the ground is 500mm (this value can be determined according to the on-site conditions);

[0079] Turn on the laser scanner and set the laser beam scanning angle so that the starting laser beam can reach the edge of one side of the lane and the ending laser beam can reach the edge of the other side of the lane;

[0080] Check the distance detected by each laser beam within the set scanning angle of the laser scanner. The correct distance value tends to increase from small to large. The curve is as follows: Figure 3 As shown by the solid line, if the distance value increases as a whole, Figure 3 As shown by the dotted line, it means that the laser beam has not completely scanned the crossbar of the calibration device, but scanned the ground. At this time, it is necessary to adjust the installation angle of the laser scanner so that the laser beam scanning area is perpendicular to the overhead direction of the detection lane, so that the distance detected by each laser beam within the set scanning angle meets the Figure 3The solid line shows the curve. Generally, depending on the lane width, the scanning angle is set between 30 and 45 degrees. The corresponding curve is obtained by taking the laser beam number as the horizontal axis and the measured distance as the vertical axis. If the laser beam hits the ground instead of the calibration device, the measured distance will increase suddenly, and the laser beams after the laser beam that hits the ground will also hit the ground (because the scanner is crooked or the laser beam has been shot out of the edge of the calibration device). Figure 3 The dotted line portion, the laser beam to the right of the initial +2 laser beam, is the last laser beam that hits the calibration device.

[0081] 12) Calibrate the vertical laser beam in the direction of the laser scanner

[0082] like Figure 4 As shown, after step 11), the laser beam with the shortest distance measured after calibration should be perpendicular to the calibration device. This laser beam is set as the starting laser beam, which will be used as a necessary condition for calculating the width and height of the vehicle in the later stage of vehicle model detection. The two laser scanners need to be calibrated separately, because installation or mechanical errors will cause them to be on different levels, resulting in different heights, and their respective starting laser beam numbers are also different.

[0083] 13) Calibrate the laser scanner horizontal distance

[0084] Shorten both ends of the calibration device crossbar so that the starting beams of the two laser scanners can just hit the corresponding edges of the crossbar. Figure 5 The ending laser beam of the laser scanner 1 shown has been emitted outside the calibration device. At this time, each laser beam should be searched forward from the ending laser beam to find the laser beam whose measured distance meets the value of H'÷Sinα. H' is the height of the laser scanner from the calibration device, and α is the angle between each laser beam and the starting beam. The angle of each laser beam is a fixed value, which can be obtained by multiplying the difference in the laser beam sequence number by the fixed angle. At this time, this laser beam is used as the ending laser beam. The solid line segment next to the dotted line in the figure represents the laser beam emitted by the laser scanner 1 outside the far edge of the calibration device, and the dotted line segment is the laser beam emitted by the laser scanner 1 to the far edge of the calibration device.

[0085] The trigonometric function l1'*sinα' can be used to calculate the length of the calibration device crossbar at this time, that is, the horizontal distance between the two laser scanners, where α' is the angle between the edge laser beam and the starting laser beam, and l1' refers to the distance from the laser scanner to the diagonally opposite edge of the crossbar measured by the edge laser beam; using a tape measure to measure the length of the calibration device crossbar can verify the calculation result and confirm that the edge laser beam is accurately found. Use the same method to calculate the horizontal distance D between the two laser scanners again for laser scanner 2. If the error of the two calculation results is less than 2.5cm, it means that the calibration is successful, otherwise it needs to be recalibrated. Calculate the average of the two horizontal distances as the final horizontal distance D between the two laser scanners.

[0086] 14) Width and height detection

[0087] like Figure 6 As shown, when calculating the width and height of the vehicle, the vertical height H1 of the laser scanner 1 from the ground must be measured first, and the distance l1 from the roof to the laser scanner 1 is measured by the laser beam that forms an angle α with the starting laser beam. The trigonometric function l1*Sinα is used to obtain the horizontal distance w1 from the roof to the scanner 1, and l1*Cosα is used to obtain the height h1 from the roof to the scanner 1. The same method is used to obtain the vertical height H2 of the laser scanner 2 from the ground, the horizontal distance w2 from the roof to the scanner 2, and the height h2 from the roof to the scanner 2. Due to different cargoes loaded on the vehicle, the highest point and the widest point are not necessarily at the two vertices of the vehicle. It is necessary to calculate w1, w2 and h1, h2 of each laser beam within the start and end angles of the two laser scanners, and take their minimum value as the final calculation basis.

[0088] The actual width of the vehicle is D-w1-w2, where D is the horizontal distance between the two laser scanners measured in the previous step.

[0089] The actual height of the vehicle is H1-h1 on one side and H2-h2 on the other side. The maximum value is taken in the application of overheight detection, and the average value is taken in the application of vehicle type identification.

[0090] It should also be noted that due to the different angles of multiple laser beams, taking laser scanner 1 as an example, α is a change value from 0 to β, β is the maximum angle of the laser beam at which scanner 1 can measure the distance to the roof. Laser beams exceeding this angle have been emitted to the distant road surface, and the return distance is too large or exceeds the range. The l (distance between the side of the vehicle and the scanner), w (horizontal distance between the side of the vehicle and the scanner), and h (height between the roof and the scanner) measured by each laser beam are different. The minimum value of w and the minimum value of h should be taken as the basis for the final calculation.

[0091] Length detection calibration:

[0092] 21) Calibrate the horizontality between the laser scanner laser beam scanning area and the detection lane in the top view direction

[0093] The correct laser beam scanning area should be parallel to the detection lane in the top-down direction, so that the length scanned by the laser beam when the vehicle passes under the laser scanner is the real length of the vehicle. Otherwise, the measured length will increase, such as Figure 7 As shown;

[0094] A laser scanner is used for length detection. The calibration device is placed directly below the laser scanner, parallel to the detection lane in the top-down direction, and the crossbar of the calibration device is extended to the maximum (theoretically, the best effect is achieved when the crossbar length is the maximum measuring range of the laser scanner, but it is impossible to make a crossbar that is too long due to processing accuracy and cost considerations). The legs of the calibration device are adjusted so that the crossbar is horizontal and stably in contact with the ground, and the top surface of the crossbar is 500mm above the ground (this value can be determined based on on-site conditions).

[0095] like Figure 8 As shown, turn on the laser scanner and set the laser beam scanning angle so that the initial laser beam can reach the edges of both sides of the crossbar of the calibration device.

[0096] Check the distance detected by each laser beam within the set scanning angle of the laser scanner. The correct distance value is a trend from large to small and then to large. The curve is as follows Fig. 9 As shown by the solid line, if the distance value increases as a whole, Fig. 9 As shown by the dotted line, it means that the laser beam has not completely scanned the crossbar of the calibration device, but scanned the ground. At this time, it is necessary to adjust the installation angle of the laser scanner so that the laser beam scanning area is parallel to the detection lane in the top-down direction, so that the distance detected by each laser beam within the set scanning angle meets the Fig. 9 The solid line shows the curve.

[0097] The laser beam scanning angle is generally set between 30 and 60 degrees. The corresponding curve is obtained by taking the laser beam number as the horizontal axis and the measured distance as the vertical axis. If the laser beam hits the ground instead of the calibration device, the distance will increase suddenly, and the laser beams after the laser beam that hits the ground will also hit the ground. Fig. 9 As shown by the dotted lines, the laser beams containing the dotted lines are the laser beams emitted outside the calibration device.

[0098] like Fig.10 As shown in the figure, the deviation of the laser beam scanning area, these laser beams from left to right only the middle part of the shot to the calibration device, the rest of the shot to the ground, so there will be Fig. 9 In the case of two dotted lines (long distance) and a solid line in the middle (short distance), the correct laser beam scanning area should measure the distance without sudden changes, such as Fig.11 shown.

[0099] 22) Length detection

[0100] like Fig.12As shown, the crossbar length c can be calculated by the distance a measured by the starting laser beam, the distance b measured by the ending laser beam, and the angle γ between the two laser beams, using the formula: 2 =a 2 +b 2 -2*a*b*Cosγ

[0101] Use a tape measure to measure the length of the current calibration device crossbar and compare it with the calculated result. If the calculated result error is less than 2.5cm, it means that the calibration is successful. Otherwise, it means that the laser beam scanning area and the detection lane are not level enough in the top-down direction, and the calibration device crossbar needs to be narrowed to recalibrate the level.

[0102] Furthermore, when the laser scanner has been installed and used for a period of time and a detection error occurs, perform calibration as follows:

[0103] 1. Width and height detection calibration

[0104] As in the installation, the laser scanners on both sides need to be calibrated separately. The calibration device is placed directly below the laser scanner. The high-brightness laser pointer on the calibration device can be used to illuminate the laser scanner to determine whether the calibration device is directly below the laser scanner. The calibration device is perpendicular to the detection lane in the top-down direction. The crossbar of the calibration device is extended to the lane width. The legs of the calibration device are adjusted by a level ruler to make the crossbar horizontal and the legs stably contact the ground. The top surface of the crossbar is 500mm above the ground (this value can be determined according to the on-site conditions);

[0105] Turn on the laser scanner and set the laser beam scanning angle so that the starting laser beam can reach the edge of one side of the lane and the ending laser beam can reach the edge of the other side of the lane;

[0106] Check the distance detected by each laser beam of the laser scanner within the set scanning angle. The correct distance value is a trend from small to large. If the distance value increases as a whole, it means that the laser beam has not completely scanned the crossbar of the calibration device, but has scanned the ground. At this time, you need to rotate the crossbar with the angle scale out of the calibration device, check the distance detected by each laser beam of the laser scanner within the set scanning angle, adjust the rotation angle of the crossbar with the angle scale, so that the distance value detected by each laser beam is a trend from small to large. The curve is shown as the solid line of the verticality calibration curve during installation, indicating that the verticality deviation of the laser scanner in the overhead direction and the detection lane has been found. Record the current deviation angle θ through the angle scale, as shown in Fig.13 shown.

[0107] Continue to align the vertical laser beam in the laser scanner's forward direction in the same way as during installation.

[0108] Next, calibrate the horizontal distance of the laser scanner. The difference from the calibration during installation is that the length calculated by the trigonometric function l1*sinα is no longer the same as the length of the crossbar of the calibration device measured with a tape measure, because the laser beam scanning area is no longer perpendicular to the detection lane in the top-down direction. At this time, the calibration device can be rotated as a whole to the deflection direction of the laser beam scanning area, and then the cross arm can be extended to the edge of the lane. The value calculated by the trigonometric function l1*sinα*cosθ is the horizontal distance D between the two laser scanners. The same method is used to calculate the laser scanner 2 again. If the error between the two calculation results and the tape measure measurement result is less than 2.5cm, it means that the calibration is successful. Otherwise, it means that the angle θ is inaccurate and needs to be recalibrated.

[0109] The result of vehicle width detection also needs to be multiplied by cosθ to be the correct value after correction. Vehicle height detection is not affected by the deflection of the laser beam scanning area.

[0110] 2. Length detection calibration

[0111] As in installation, place the calibration device directly below the laser scanner, parallel to the detection lane in the top view, extend the calibration device crossbar to the maximum, adjust the calibration device legs so that the crossbar is horizontal and the legs are stably in contact with the ground, and the top surface of the crossbar is 500mm above the ground (this value can be determined based on on-site conditions).

[0112] Turn on the laser scanner and set the laser beam scanning angle so that the initial laser beam can reach the edges of both sides of the crossbar of the calibration device.

[0113] Check the distance detected by each laser beam of the laser scanner within the set scanning angle. The correct distance value is a trend from large to small and then to large. If the distance value increases as a whole, it means that the laser beam has not completely scanned the crossbar of the calibration device, but has scanned the ground. At this time, it is necessary to rotate the crossbar with the angle scale out of the calibration device, check the distance detected by each laser beam of the laser scanner within the set scanning angle, adjust the rotation angle of the crossbar with the angle scale, so that the distance value detected by each laser beam is a trend from large to small and then to large. The curve is shown as the solid line of the verticality calibration curve during installation, indicating that the parallelism deviation between the laser scanner and the detection lane in the overhead direction has been found, and the current deviation angle ω is recorded by the angle scale, as shown in Fig.14 shown.

[0114] When calculating the length, multiply the result by cosω to get the correct value after correction.

[0115] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A calibration method for a laser vehicle type detection and calibration device, characterized in that: When the laser vehicle type detection and calibration device is installed for the first time, it includes width and height detection calibration and length detection calibration, wherein the width and height detection calibration specifically includes the following steps: 11) Calibrate the verticality between the laser scanner laser beam scanning area and the detection lane top view direction The calibration device is arranged directly below the laser scanner, and the light emitted by the laser pointer is perpendicular to the crossbar of the calibration device. The laser pointer on the calibration device is used to illuminate the laser scanner to determine whether the calibration device is directly below the laser scanner. Adjust the calibration device to be perpendicular to the detection lane in the top view direction, adjust the crossbar of the calibration device to the lane width, and use a level ruler to adjust each leg of the calibration device so that the crossbar is horizontal and each leg is stably in contact with the ground; Turn on the laser scanner and set the laser beam scanning angle so that the starting laser beam can reach the edge of one side of the lane and the ending laser beam can reach the edge of the other side of the lane; check the distance detected by each laser beam of the laser scanner within the set scanning angle. The correct distance value is a trend from small to large. Ensure that within the set scanning angle, the laser scanner's laser beams are all scanned onto the crossbar of the calibration device; 12) Calibrate the vertical laser beam in the direction of the laser scanner After step 11), the laser beam with the shortest distance measured after calibration should be perpendicular to the calibration device, and this laser beam is set as the starting laser beam, which will be used as a necessary condition for calculating the width and height of the vehicle in the later stage of vehicle type detection; 13) Calibrate the laser scanner horizontal distance Adjust the crossbar of the calibration device so that the starting beams of the two laser scanners just hit the corresponding edges of the crossbar; The length of the crossbar of the calibration device at this time can be calculated using the trigonometric function l1'*sinα', that is, the horizontal distance between the two laser scanners, where α' is the angle between the edge laser beam and the starting laser beam, and l1' refers to the distance from the laser scanner to the diagonally opposite edge of the crossbar measured by the edge laser beam; 14) Width and height detection When calculating the width and height of a vehicle, first measure the vertical height H1 of the laser scanner from the ground, and use the laser beam that forms an angle α with the starting laser beam to measure the distance l1 from the roof to the laser scanner. Use the trigonometric function l1*Sinα to get the horizontal distance w1 from the roof to the laser scanner, and l1*Cosα to get the height h1 from the roof to the laser scanner. Use the same method to get the vertical height H2 of another laser scanner from the ground, the horizontal distance w2 from the roof to the laser scanner, and the height h2 from the roof to the laser scanner. Because the highest point and the widest point are not necessarily at the two vertices of the vehicle due to different cargoes loaded on the vehicle, it is necessary to calculate w1, w2 and h1, h2 of each laser beam within the start and end angles of the two laser scanners, and take their minimum value as the final calculation basis. The actual width of the vehicle is D-w1-w2, where D is the horizontal distance between the two laser scanners; The actual height of the vehicle is H1-h1 on one side and H2-h2 on the other side; The actual height of the vehicle. The maximum value is taken when applying super-height detection, and the average value is taken when distinguishing vehicle types. The length detection calibration specifically includes the following steps: 21) Calibrate the horizontality between the laser scanner laser beam scanning area and the detection lane in the top view direction The length detection uses a laser scanner. The calibration device is placed directly below the laser scanner. The calibration device is parallel to the detection lane in the top view direction. The crossbar of the calibration device is adjusted to the longest. The legs of the calibration device are adjusted to make the crossbar horizontal and the legs stably contact the ground. Turn on the laser scanner and set the laser beam scanning angle so that the initial laser beam can reach the edges of both sides of the crossbar of the calibration device; and ensure that within the set scanning angle, the laser beam of the laser scanner is fully scanned onto the crossbar of the calibration device; 22) Length detection The crossbar length c can be calculated by the distance a measured by the starting laser beam, the distance b measured by the ending laser beam, and the angle γ between the two laser beams, using the formula: c 2 =a 2 +b 2 -2*a*b*Cosγ; The laser vehicle type detection and calibration device includes a straight retractable cross bar, with multiple groups of legs that can be retracted up and down connected below the cross bar, a level ruler fixedly installed in the middle of the cross bar, a laser indicator perpendicular to the cross bar at one end of the cross bar, and another cross bar with an angular scale that can rotate clockwise and counterclockwise below the cross bar.

2. The calibration method of the laser vehicle type detection and calibration device according to claim 1, characterized in that: There is another cross bar with an angle scale below the cross bar, which can rotate clockwise and counterclockwise by a maximum of 20 degrees; the support foot has scales and threads, and the support foot is connected to the cross bar through threads.

3. The calibration method of the laser vehicle type detection and calibration device according to claim 1, characterized in that: In steps 11) and 21), adjust the feet of the calibration device so that the top surface of the crossbar is 500 mm above the ground.

4. The calibration method of the laser vehicle type detection and calibration device according to claim 1, characterized in that: In steps 11) and 21), the laser scanners on both sides need to be calibrated separately.

5. The calibration method of the laser vehicle type detection and calibration device according to claim 1, characterized in that: In step 13), after adjusting the length of the crossbar of the calibration device, if the ending laser beam of a laser scanner is emitted outside the calibration device, each laser beam should be searched from the ending laser beam forward to find the laser beam whose measured distance meets the value of H'÷Sinα, where H' is the height of the laser scanner from the calibration device, α is the angle between each laser beam and the starting beam, and the angle between each laser beam and the starting beam is a fixed value, which can be obtained by multiplying the difference in laser beam numbers by the fixed angle. At this time, this laser beam is used as the ending laser beam.

6. The calibration method of the laser vehicle type detection and calibration device according to claim 1, characterized in that: In step 13), the laser beam calculation result is verified by measuring the length of the crossbar of the calibration device with a tape measure to confirm that the edge laser beam is accurately found.

7. The calibration method of the laser vehicle type detection and calibration device according to claim 1, characterized in that: In step 13), the horizontal distance D between the two laser scanners is calculated again using the same method for another laser scanner. If the error between the two calculation results is less than 2.5 cm, the calibration is successful, otherwise recalibration is required; the average of the two horizontal distances is calculated as the final horizontal distance D between the two laser scanners.

8. The calibration method of the laser vehicle type detection and calibration device according to claim 1, characterized in that: In step 22), use a tape measure to measure the current crossbar length of the calibration device and compare it with the calculated crossbar length. If the error of the calculated result is less than 2.5 cm, it means that the calibration is successful. Otherwise, it means that the laser beam scanning area and the detection lane are not level enough in the top-down direction, and the calibration device crossbar needs to be narrowed to recalibrate the level.

9. The calibration method of the laser vehicle type detection and calibration device according to any one of claims 1 to 2, characterized in that: After the laser scanner has been installed and used for a period of time, the calibration method when detection errors occur, the width and height detection calibration is carried out as follows: The laser scanners on both sides need to be calibrated separately. Place the calibration device directly below the laser scanner. Use the high-brightness laser pointer on the calibration device to illuminate the laser scanner to determine whether the calibration device is directly below the laser scanner. The calibration device is perpendicular to the detection lane in the top-down direction. Adjust the crossbar of the calibration device to the lane width. Use the level ruler to adjust each leg of the calibration device so that the crossbar is horizontal and each leg is stably in contact with the ground. Turn on the laser scanner and set the laser beam scanning angle so that the starting laser beam can reach the edge of one side of the lane and the ending laser beam can reach the edge of the other side of the lane; Check the distance detected by each laser beam of the laser scanner within the set scanning angle. The correct distance value is a trend from small to large. Ensure that within the set scanning angle, the laser beam of the laser scanner scans all the laser beams on the calibration device crossbar. If the laser beam does not scan all the crossbar of the calibration device but scans the ground, you need to rotate the crossbar with the angle scale out of the calibration device, check the distance detected by each laser beam of the laser scanner within the set scanning angle, adjust the rotation angle of the crossbar with the angle scale, find the vertical deviation between the laser scanner and the detection lane in the top-view direction, and record the current deviation angle θ through the angle scale. Continue to calibrate the vertical laser beam in the front view direction of the laser scanner. After the previous calibration, the laser beam with the shortest distance measured should be perpendicular to the calibration device. Set this laser beam as the starting laser beam. Then calibrate the horizontal distance of the laser scanner, rotate the calibration device as a whole to the deflection direction of the laser beam scanning area, and then adjust the length of the crossbar to the edge of the lane. Calculate the horizontal distance D' between the two laser scanners using the trigonometric function l1*sinα*cosθ; calculate the other laser scan again in the same way. If the error between the two calculation results and the tape measure measurement result is less than 2.5cm, it means that the calibration is successful. Otherwise, it means that the angle θ is inaccurate and needs to be recalibrated. When calculating the width and height of a vehicle, first measure the vertical height H1 of the laser scanner from the ground, and use the laser beam that forms an angle α with the starting laser beam to measure the distance l1 from the roof to the laser scanner. Use the trigonometric function l1*Sinα*cosθ to get the horizontal distance w1' from the roof to the laser scanner, and l1*Cosα*cosθ to get the height h1 from the roof to the laser scanner. Use the same method to get the vertical height H2 of another laser scanner from the ground, the horizontal distance w2' from the roof to the laser scanner, and the height h2 from the roof to the laser scanner. Because the highest point and the widest point are not necessarily at the two vertices of the vehicle due to different cargoes loaded on the vehicle, it is necessary to calculate w1', w2' and h1, h2 of each laser beam within the start and end angles of the two laser scanners, and take their minimum value as the final calculation basis. The actual width of the vehicle is D'-w1'-w2'; The actual height of the vehicle is H1-h1 on one side and H2-h2 on the other side; The length detection calibration is carried out as follows: Place the calibration device directly below the laser scanner, parallel to the detection lane in the top view direction, extend the crossbar of the calibration device to the maximum, and adjust the legs of the calibration device to make the crossbar horizontal and the legs stably contact the ground; Turn on the laser scanner and set the laser beam scanning angle so that the initial laser beam can reach the edges of both sides of the crossbar of the calibration device; Check the distance detected by each laser beam of the laser scanner within the set scanning angle. The correct distance value is a trend from large to small and then to large. If the laser beam does not scan all of the crossbar of the calibration device, but scans the ground, it is necessary to rotate the crossbar with the angle scale out of the calibration device, check the distance detected by each laser beam of the laser scanner within the set scanning angle, and adjust the rotation angle of the crossbar with the angle scale so that the distance value detected by each laser beam is a trend from large to small and then to large. This indicates that the parallelism deviation between the laser scanner and the detection lane in the top-view direction has been found, and the current deviation angle ω is recorded through the angle scale. The crossbar length c can be calculated by the distance a measured by the starting laser beam, the distance b measured by the ending laser beam, and the angle γ between the two laser beams, using the formula: c 2 =(a 2 +b 2 -2*a*b*Cosγ)*cosω。

Images