Volatile organic compound differential absorption laser radar system calibration device and method

Abstract

The invention provides a volatile organic compound differential absorption laser radar system calibration device and method. The volatile organic compound differential absorption laser radar system calibration device comprises a calibration cylinder, a laser radar, point type measurement equipment and two brackets, a matt velvet layer is mounted in the calibration cylinder, an exhaust hole is formed in the bottom of the calibration cylinder, and the calibration cylinder is in the shape of a circular truncated cone; the calibration cylinder and the laser radar are installed on the two supports respectively. According to the calibration device for the volatile organic compound differential absorption laser radar system, diffusion of target gas can be limited by adopting the calibration cylinder, the actual concentration change of the target gas can be accurately detected through the point type measurement equipment and the controlled volume of the released gas, and the laser radar is a remote measuring instrument with distance resolution. The actual inversion concentration is the average concentration within the range resolution, and the accuracy of detection within the range resolution at the designed distance can be accurately reflected through the calibration cylinder.

Description

Technical Field

[0001] The present invention relates to the field of differential absorption laser radar, and in particular to a volatile organic compound differential absorption laser radar system calibration device and method. Background Art

[0002] Differential absorption lidar is a technology for remotely monitoring gas concentrations. It is currently an effective means of long-distance telemetry of volatile organic compounds (VOCs). It can perform large-scale remote and accurate measurements of emission sources such as chemical parks, smelters, and chemical storage tanks. The working mode of the differential absorption lidar for volatile organic compounds is to emit two laser beams of the same power but different wavelengths. One beam is located at the absorption peak of the absorption spectrum of the target gas, called the on wavelength; the other beam is located at the absorption valley of the absorption spectrum, called the off wavelength. Since the target gas has different absorption rates for the two laser beams, the echo signals received by the lidar will be significantly different. The concentration of the target gas in the atmosphere can be deduced by taking the difference between the signals of different intensities at the two wavelengths.

[0003] Unlike traditional laser radars, VOC differential absorption laser radars need to meet the differential of target gases. One gas requires two wavelengths of lasers. If multiple gases are to be measured simultaneously, more wavelengths are required. Therefore, VOC laser radars usually use tunable lasers with adjustable wavelengths as light sources. Due to the complexity of the laser system, it is difficult to ensure that the laser power emitted at the on wavelength and the off wavelength is consistent. The laser used to detect the target gas may also have wavelength drift, which may cause errors in the inversion of the target gas concentration. In the prior art, the calibration method usually uses a gas absorption cell, but the absorption cell will produce multiple scatterings, introducing new errors.

[0004] Therefore, it is necessary to provide a volatile organic compound differential absorption lidar system calibration device and method to solve the above technical problems. Summary of the invention

[0005] The present invention provides a volatile organic compound differential absorption laser radar system calibration device, which solves the problem that the calibration method in the prior art usually uses a gas absorption cell, but the absorption cell will produce multiple scattering and introduce new errors.

[0006] In order to solve the above technical problems, the present invention provides a volatile organic compound differential absorption laser radar system calibration device, comprising:

[0007] calibration cylinder, lidar and point measurement equipment and two stands;

[0008] A matte fleece layer is installed inside the calibration cylinder, an exhaust hole is opened at the bottom of the calibration cylinder, and the calibration cylinder is in the shape of a truncated cone;

[0009] The calibration cylinder and the laser radar are respectively mounted on the two brackets;

[0010] The detection end of the point-type measuring device is suspended below the exhaust hole;

[0011] When in use, the two brackets are placed at a preset distance, and the center of the calibration cylinder and the output end of the laser radar are located on the same axis.

[0012] Preferably, the volatile organic compound differential absorption lidar system calibration device also includes two laser spotlights, and the two laser spotlights are correspondingly mounted on the bracket through a mounting plate, and the output ends of the two laser spotlights are arranged in opposite directions.

[0013] Preferably, the calibration cylinder is made of plastic.

[0014] Preferably, the bracket comprises a base, a lifting assembly and a mounting platform, the lifting assembly is mounted on the base, the mounting platform comprises a mounting box, a slide, a moving part and a plurality of slide bars, a plurality of the slide bars are installed inside the mounting box at intervals, the slide is sleeved on the slide bars, the moving part is used to drive the slide to move along the slide bars, and the mounting box is rotatably mounted on the output end of the lifting assembly;

[0015] The calibration tube and the laser radar are respectively mounted on the corresponding slides, and the laser spotlight is mounted on the slide via the mounting plate.

[0016] Preferably, the lifting assembly includes a threaded shaft, a rotating member, a threaded sleeve and a limit rod, the threaded shaft is rotatably installed on the top of the base, the threaded sleeve is threadedly connected to the threaded shaft, the limit rod is installed on the base and arranged adjacent to the threaded shaft, the threaded sleeve is slidably connected to the limit rod via a connecting ear, and the rotating member is used to drive the threaded shaft to rotate.

[0017] Preferably, a rotating sleeve is installed at the bottom of the installation box, and the rotating sleeve is arranged on the top of the threaded sleeve. The volatile organic compound differential absorption laser radar system calibration device also includes a rotating member, and the rotating member is used to drive the rotating sleeve to rotate.

[0018] Preferably, the volatile organic compound differential absorption laser radar system calibration device further includes a driving device, the driving device includes a motor, a driving shaft, a main gear, a driving shaft and a limiter, the motor is mounted on the base, the driving shaft is mounted on the output end of the motor, the main gear is sleeved on the driving shaft, and the main gear is detachably mounted on the driving shaft through the limiter;

[0019] The rotating member is the first slave gear, which is installed on the threaded shaft. The rotating member is the second slave gear, which is installed on the rotating sleeve. When the rotating member is working, the main gear is engaged with the rotating member. When the rotating member is working, the main gear is engaged with the rotating member.

[0020] Preferably, the movable member is a bar frame, the movable member is installed at the bottom of the slide, the mounting platform is provided with a circular hole corresponding to the position of the movable member, the driving device also includes a driving shaft, the driving shaft is eccentrically installed on the top of the main gear, and the driving shaft is located below the circular hole.

[0021] Preferably, a rubber sleeve is provided between the rotating sleeve and the threaded sleeve.

[0022] The present invention also provides a volatile organic compound differential absorption laser radar system calibration method, using the volatile organic compound differential absorption laser radar system calibration device, comprising the following steps:

[0023] S1. Place the calibration tube and laser radar on the same axis in an open area, with a preset distance between them, start the laser radar, adjust the laser wavelength in sequence, and observe the echo signal. If the echo signal has a bump or mutation, adjust the position of the calibration tube to make the echo signal corresponding to each laser wavelength balanced and stable;

[0024] S2. Release the target gas to be measured through the small hole at the bottom of the calibration cylinder, and monitor the concentration change of the target gas in real time through the probe of the point measurement device;

[0025] S3, start the laser radar to detect and invert the real-time concentration of the target gas to be measured;

[0026] S4. Perform calibration calculations. First, release the target gas volume, and measure the concentration changes monitored by the point measurement device. According to the diffusion theory, accurately calculate the curve of the gas concentration in the calibration cylinder over time.

[0027] S5. The laser radar inverts the target gas concentration measured at the preset distance, and uses the calibration cylinder concentration curve calculated in S as the calibration gold standard to calibrate the laser radar.

[0028] Compared with the related art, the volatile organic compound differential absorption laser radar system calibration device provided by the present invention has the following beneficial effects:

[0029] The present invention provides a volatile organic compound differential absorption laser radar system calibration device, which uses a calibration tube to limit the diffusion of target gas, and a point measurement device plus a controlled released gas volume can accurately detect the concentration change of the actual target gas. Moreover, the laser radar is a remote sensing instrument with a distance resolution, and the actual inversion concentration is the average concentration within the distance resolution. The calibration tube can accurately reflect the accuracy of its detection within a distance resolution at the designed distance.

[0030] Compared with the calibration scheme using a gas absorption cell, calibrating the entire lidar directly in the atmospheric environment is more scientific and has operability and repeatability in the actual generation and deployment of lidars. In addition, by setting a matte velvet layer on the inside of the calibration tube, multiple scattering of lasers is reduced to improve accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of the structure of a volatile organic compound differential absorption laser radar system calibration device provided by the present invention;

[0032] Figure 2 A schematic diagram of the structure of the bracket and the calibration cylinder provided by the present invention;

[0033] Figure 3 is a schematic diagram of the three-dimensional structure of the bracket and the calibration cylinder;

[0034] Figure 4 for Figure 2 An enlarged schematic diagram of part A is shown;

[0035] Figure 5 for Figure 3 A bottom view of the portion shown;

[0036] Figure 6 for Figure 4 An enlarged schematic diagram of part B is shown;

[0037] Figure 7 The schematic diagram of the structure of the main gear and the rotating member provided by the present invention, wherein: Figure 7 (a) is a schematic diagram of the meshing of the main gear and the rotating part. Figure 7 (b) is a schematic diagram of the positioning pin being inserted into the corresponding socket;

[0038] Figure 8 A schematic diagram of the structure of the driving shaft provided by the present invention inserted into the moving member;

[0039] Fig. 9 This is a schematic diagram of the structure of the moving member driving the slide to move provided by the present invention, wherein: Fig. 9 (a) is a schematic diagram of the slide located in the middle of the slide bar. Fig. 9(b) is a schematic diagram showing that the driving shaft rotates clockwise to cause the driving shaft to drive the slide table to slide along the slide rod through the moving member;

[0040] Fig.10 A flowchart of the steps of the volatile organic compound differential absorption laser radar system calibration method provided by the present invention.

[0041] Numbers in the figure:

[0042] 1. Calibration cylinder; 11. Matt fleece layer; 12. Exhaust hole;

[0043] 2. LiDAR;

[0044] 3. Point measuring equipment; 31. Assembly plate;

[0045] 4. Base;

[0046] 5. Lifting assembly; 51. Threaded shaft; 52. Rotating member; 53. Threaded sleeve; 54. Limit rod;

[0047] 531, connecting ear; 532, rubber sleeve;

[0048] 6. driving device; 61. motor; 62. driving shaft; 63. main gear; 64. driving shaft; 65. limiting member;

[0049] 621, jack; 631, fixing sleeve; 651, U-shaped handle; 652, positioning pin; 653, first nut;

[0050] 7. Mounting table; 71. Mounting box; 72. Sliding table; 73. Sliding rod; 74. Moving part;

[0051] 711, rotating sleeve; 712, circular hole;

[0052] 8. Laser spotlight; 81. Mounting plate;

[0053] 9. Rotating parts;

[0054] 10. Locking device; 101. Locking plate; 102. Locking pin; 103. Driving block; 104. Second nut; 100. Bracket. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] The invention provides a volatile organic compound differential absorption laser radar system calibration device.

[0057] Please refer to Figure 1 to Figure 2 In one embodiment of the present invention, the volatile organic compound differential absorption laser radar system calibration device comprises:

[0058] Calibration cylinder 1, laser radar 2 and point measurement device 3 and two brackets 100;

[0059] A matte fleece layer 11 is installed inside the calibration cylinder 1, an exhaust hole 12 is opened at the bottom of the calibration cylinder 1, and the calibration cylinder 1 is arranged in a truncated cone shape;

[0060] The calibration cylinder 1 and the laser radar 2 are respectively mounted on the two brackets 100;

[0061] The detection end of the point measuring device 3 is suspended below the exhaust hole 12;

[0062] When in use, the two brackets 100 are placed at a preset distance, and the center of the calibration cylinder 1 and the output end of the laser radar 2 are located on the same axis.

[0063] In this embodiment, the calibration cylinder 1 is slightly larger than the volume of the receiving field of view of the laser radar 2 at the measurement position;

[0064] Place the calibration tube 1 and the laser radar 2 on the same axis in an open area, with a preset distance between them (such as 80m, 100m, etc.), start the laser radar 2, adjust the laser wavelength in turn, observe the echo signal, if the echo signal has a bump or mutation, adjust the position of the calibration tube 1 to make the echo signal corresponding to each laser wavelength balanced and stable; release the target gas to be measured through the small hole under the calibration tube 1, and monitor the concentration change of the target gas in real time through the probe of the point measurement device 3; start the laser radar 2 for detection, and invert the real-time concentration of the target gas to be measured; perform calibration calculations, first release the target gas volume, and monitor the concentration change monitored by the point measurement device 3, and accurately calculate the curve of the gas concentration in the calibration tube 1 over time according to the diffusion theory; the laser radar 2 inverts the target gas concentration measured at the preset distance, and uses the calibration tube 1 concentration curve calculated above as the calibration gold standard to calibrate the laser radar 2;

[0065] Among them, for the differential absorption laser radar 2 that can detect multiple gases, each time a different gas is released, the accuracy of each gas detection can be accurately calibrated.

[0066] The use of the calibration tube 1 can limit the diffusion of the target gas, and the point measurement device 3 plus the controlled released gas volume can accurately detect the concentration change of the actual target gas. Moreover, the laser radar 2 is a remote sensing instrument with distance resolution. The actual inversion concentration is the average concentration within the distance resolution. The calibration tube 1 can accurately reflect the accuracy of its detection within a distance resolution at the designed distance.

[0067] Compared with the calibration scheme using a gas absorption cell, calibrating the entire laser radar 2 directly in the atmospheric environment is more scientific and has operability and repeatability in the actual generation and deployment of the laser radar 2; and by providing a matte velvet layer 11 on the inner lining of the calibration tube 1, multiple scattering of lasers is reduced to improve accuracy.

[0068] The end with a larger diameter of the calibration cylinder 1 is sealed, and the end with a smaller diameter is open. The calibration cylinder 1 also includes an end cap and a sealing plug (not shown), which are sleeved on the open end of the calibration cylinder 1. The sealing plug is used to block the exhaust hole 12. The sealing plug and the end cap can be disassembled accordingly when in use. A sealing ring is arranged on the inner side of the end cap to ensure the sealing and stability during connection; and a pipe head is arranged on the end cap, and a valve is arranged on the pipe head, through which the target gas (such as methane, acetylene and other volatile organic gases) can be added to the interior of the calibration cylinder 1;

[0069] The calibration tube 1 can be made of different sizes according to different distances, so that the calibration tube 1 is slightly larger than the volume of the receiving field of view of the laser radar 2 at the measuring position;

[0070] See also Figure 1 and Figure 2 As an optional method of this embodiment, the volatile organic compound differential absorption lidar system calibration device also includes two laser spotlights 8, and the two laser spotlights 8 are correspondingly installed on the bracket 100 through a mounting plate 81, and the output ends of the two laser spotlights 8 are arranged in opposite directions.

[0071] The light beams emitted by the two laser spotlights 8 are aligned with the center lines of the laser radar 2 and the calibration cylinder 1 .

[0072] By arranging a laser spotlight 8 on the bracket 100, when the calibration tube 1 and the laser radar 2 are placed at a preset distance, the two laser spotlights 8 can be activated to assist in locating the positions of the two brackets 100, so that the calibration tube 1 and the laser radar 2 are placed on the same axis;

[0073] By starting the laser spotlights 8, the two laser spotlights 8 emit beam lines. When the laser radar 2 and the calibration tube 1 are located on the same axis, the beam lines emitted by the two laser spotlights 8 should overlap. When two beam points appear on the mounting plate 81, they do not overlap. This can assist in quickly adjusting the alignment of the calibration tube 1 and the laser radar 2, that is, to be located on the same axis.

[0074] Of course, the specific calibration is whether the tube 1 and the laser radar 2 are aligned, so as to ensure that the echo signal corresponding to each laser wavelength is balanced and stable.

[0075] Preferably, the light emitted by the laser spotlight 8 is green, which is easier to identify, and the mounting plate 81 is an opaque plate, and a light shield (not shown) is provided on the mounting plate 81 above the laser spotlight 8 to reduce the influence of daytime light, so that the light emitted by the laser spotlight 8 can be more clearly identified when it shines on the mounting plate 81.

[0076] As an optional method of this embodiment, a laser spotlight 8 can be set on one bracket 100, and the laser spotlight 8 can be replaced with a target point on the mounting plate 81 on the other bracket 100. When the light emitted by the laser spotlight 8 on one bracket 100 is irradiated on the target point, the calibration tube 1 is aligned with the laser radar 2;

[0077] The target point may be a colored origin, or a circular reflector may be used. When the light emitted by the laser spotlight 8 is reflected, it is aligned.

[0078] As an optional manner of this embodiment, the calibration cylinder 1 is made of plastic.

[0079] Made of plastic, it is light and low cost.

[0080] See also Figure 3 and Figure 4 As an optional mode of this embodiment, the bracket 100 includes a base 4, a lifting assembly 5 and a mounting platform 7, the lifting assembly 5 is installed on the base 4, the mounting platform 7 includes a mounting box 71, a slide 72, a moving member 74 and a plurality of slide bars 73, a plurality of the slide bars 73 are installed inside the mounting box 71 at intervals, the slide 72 is sleeved on the slide bar 73, the moving member 74 is used to drive the slide 72 to move along the slide bar 73, and the mounting box 71 is rotatably installed at the output end of the lifting assembly 5;

[0081] The calibration tube 1 and the laser radar 2 are respectively mounted on the corresponding slide 72 , and the laser spotlight 8 is mounted on the slide 72 via the mounting plate 81 .

[0082] After placing the two brackets 100 at a preset distance and roughly adjusting the position of the brackets 100, the light emitted by the laser spotlight 8 is irradiated on the corresponding mounting plate 81, and then the height of the lifting component 5, the horizontal adjustment of the mounting table 7, and the angle adjustment of the rotating mounting table 7 can be further accurately adjusted to make the light of the two laser spotlights 8 overlap, so that the calibration tube 1 and the laser radar 2 are aligned. The entire bracket 100 is moved directly. It is difficult to grasp the moving distance and angle by manual moving, and it is not easy to align the calibration tube 1 and the laser radar 2.

[0083] Among them, the lifting component 5 adjusts the height of the calibration cylinder 1 (or laser radar 2) by adjusting the height of the mounting platform 7, the moving part 74 drives the slide 72 to move along the slide rod 73 to adjust the horizontal position of the calibration cylinder 1 (or laser radar 2), and the mounting platform 7 is rotatably installed at the output end of the lifting component 5, that is, the angle of the mounting platform 7 can be adjusted, thereby adjusting the angle of the calibration cylinder 1 (or laser radar 2).

[0084] See also Figure 1 The calibration tube 1 and the laser radar 2 are installed on the slide 72 of their respective brackets 100 through corresponding installation components.

[0085] In this embodiment, two groups of slide bars 73 are provided, which are respectively located at the two ends of the installation box 71, and each group of slide bars 73 has two slide bars. The two ends of the slide platform 72 are correspondingly sleeved on the two groups of slide bars 73 to form a sliding assembly.

[0086] See also Figure 4 As an optional method of this embodiment, the lifting assembly 5 includes a threaded shaft 51, a rotating member 52, a threaded sleeve 53 and a limiting rod 54. The threaded shaft 51 is rotatably installed on the top of the base 4. The threaded sleeve 53 is threadedly connected to the threaded shaft 51. The limiting rod 54 is installed on the base 4 and is arranged adjacent to the threaded shaft 51. The threaded sleeve 53 is slidably connected to the limiting rod 54 through a connecting ear 531. The rotating member 52 is used to drive the threaded shaft 51 to rotate.

[0087] When it is necessary to raise or lower the height of the mounting platform 7 to adjust the height of the calibration cylinder 1 (or laser radar 2), the rotating member 52 drives the threaded shaft 51 to rotate clockwise or counterclockwise, and the threaded sleeve 53 moves upward or downward along the threaded shaft 51, thereby driving the mounting platform 7 to move upward or downward to adjust the height of the calibration cylinder 1 (or laser radar 2). By using the threaded structure to adjust the height of the calibration cylinder 1 (or laser radar 2), the adjustment interval is small, and the adjustment can be performed more stably and accurately.

[0088] See also Figure 2 The point measuring device 3 is mounted on the slide 72 through the mounting plate 31 and is located below the exhaust hole 12 .

[0089] The point measurement device 3 is a VOCs point measurement instrument, which is a device used to measure the concentration of volatile organic compounds at a specific location.

[0090] As an optional method of this embodiment, the lifting component 5 can also adopt electric push cylinders, air cylinders and other equipment.

[0091] See also Figure 4 As an optional method of this embodiment, a rotating sleeve 711 is installed at the bottom of the installation box 71, and the rotating sleeve 711 is sleeved on the top of the threaded sleeve 53. The volatile organic compound differential absorption laser radar system calibration device also includes a rotating member 9, and the rotating member 9 is used to drive the rotating sleeve 711 to rotate.

[0092] The rotating sleeve 711 is driven by the rotating member 9 to drive the installation box 71 to rotate, thereby driving the slide 72 to rotate, so as to adjust the angle of the calibration cylinder 1 (or the laser radar 2).

[0093] After rough adjustment, when two corresponding light spots of the laser spotlight 8 appear on the mounting plate 81, but the two light spots still cannot overlap or be located on the same vertical line after horizontal adjustment, there is an angle deviation, and the angle of the calibration tube 1 (or laser radar 2) is adjusted.

[0094] As an optional method of this embodiment, the rotating member 9 includes a mounting frame, a rotating motor, and a gear set. The rotating motor is mounted on the base 4 through the mounting frame, and the gear set is drivingly connected to the output shaft of the rotating motor and the rotating sleeve 711;

[0095] The rotating member 52 is a rotating motor, which is mounted on the base 4 , and an output shaft of the rotating motor is connected to the threaded shaft 51 .

[0096] As another optional mode of this embodiment, the volatile organic compound differential absorption laser radar system calibration device further includes a driving device 6, the driving device 6 includes a motor 61, a driving shaft 62, a main gear 63, a driving shaft 64 and a stopper 65, the motor 61 is mounted on the base 4, the driving shaft 62 is mounted on the output end of the motor 61, the main gear 63 is sleeved on the driving shaft 62, and the main gear 63 is detachably mounted on the driving shaft 62 through the stopper 65;

[0097] The rotating member 52 is the first slave gear, and the rotating member 52 is installed on the threaded shaft 51. The rotating member 9 is the second slave gear, and the rotating member 9 is installed on the rotating sleeve 711. When the rotating member 9 is working, the main gear 63 is engaged with the rotating member 9. When the rotating member 52 is working, the main gear 63 is engaged with the rotating member 52.

[0098] Please refer to Figure 7 (a) and Figure 7 (b) When it is necessary to adjust the angle of the calibration cylinder 1 (or laser radar 2), first unlock the main gear 63 through the limit member 65, and then move the main gear 63 up to engage with the rotating member 9 (the second slave gear). The limit member 65 connects the main gear 63 and the drive shaft 62. At this time, the motor 61 drives the drive shaft 62 to rotate, and the main gear 63 drives the rotating member 9 (the second slave gear) to rotate, thereby driving the rotating sleeve 711 to rotate. The rotating sleeve 711 adjusts the angle of the calibration cylinder 1 (or laser radar 2) through the mounting table 7.

[0099] When the height of the calibration cylinder 1 needs to be adjusted, the main gear 63 is meshed with the rotating part 52, and the motor 61 is started to drive the driving shaft 62 to rotate to drive the threaded shaft 51 to rotate clockwise or counterclockwise, thereby driving the threaded sleeve 53 to drive the mounting platform 7 to rise or fall, thereby adjusting the height of the calibration cylinder 1 (or laser radar 2).

[0100] Thus, by using the main gear 63 of the driving device 6 to mesh with the rotating member 9 or the rotating member 52, the angle adjustment and height adjustment of the calibration cylinder 1 (or the laser radar 2) can be achieved;

[0101] In this embodiment, when both the angle and height of the calibration cylinder 1 (or laser radar 2) need to be adjusted, the angle of the calibration cylinder 1 (or laser radar 2) is adjusted first, and then the height is adjusted.

[0102] The driving shaft 62 is driven to adjust the tooth direction of the main gear 63 so that it is aligned with the tooth groove of the first slave gear or the second slave gear, thereby achieving corresponding assembly.

[0103] Please refer again Figure 4 The movable member 74 is a bar frame, and the movable member 74 is installed at the bottom of the slide 72. The mounting platform 7 is provided with a circular hole 712 at a position corresponding to the movable member 74. The driving device 6 also includes a driving shaft 64, and the driving shaft 64 is eccentrically installed on the top of the main gear 63, and the driving shaft 64 is located below the circular hole 712.

[0104] Please refer to Figure 8 and Fig. 9When it is necessary to adjust the horizontal position of the calibration cylinder 1 (or the laser radar 2), the main gear 63 is moved up and located above the rotating member 9 (the second slave gear). At the same time, the driving shaft 64 on the main gear 63 passes through the circular hole 712 and is inserted into the moving member 74 (bar frame). The motor 61 drives the driving shaft 62 to rotate clockwise or counterclockwise, driving the shaft 64 to slide along the inside of the moving member 74 (bar frame), and pushing the moving member 74 (bar frame) to drive the slide 72 to move along one end or the other end of the slide rod 73, thereby driving the slide 72 to move along the slide rod 73.

[0105] That is, by using the main gear 63 of the driving device 6 to mesh with the rotating member 9 or the rotating member 52, and adjusting the main gear 63 to be located above the rotating member 9, the driving shaft 64 is correspondingly inserted into the moving member 74 (bar frame), so that the angle adjustment, height adjustment and horizontal movement of the calibration cylinder 1 (or laser radar 2) can be achieved, reducing the use of driving equipment and simplifying the structure;

[0106] Among them, when the height, angle and horizontal position of the calibration cylinder 1 (or laser radar 2) need to be adjusted, the angle or horizontal position is adjusted first, and the height is adjusted last, so as to ensure that the main gear 63 can be assembled with the rotating part 9 (second slave gear), and the driving shaft 64 can be assembled with the moving part 74 (bar frame).

[0107] See also Figure 6 Preferably, a rubber sleeve 532 is provided between the rotating sleeve 711 and the threaded sleeve 53 .

[0108] By setting a rubber sleeve 532 between the rotating sleeve 711 and the threaded sleeve 53, the friction between the rotating sleeve 711 and the threaded sleeve 53 can be increased. After the main gear 63 is separated from the rotating member 9 (the second slave gear), the mounting platform 7 will not change its angle without the action of external force.

[0109] The rubber sleeve 532 is installed on the inner wall of the rotating sleeve 711 or the outer surface of the threaded sleeve 53; wherein the top end of the threaded sleeve 53 is a sealing arrangement.

[0110] As a preferred embodiment of the present embodiment, a locking device 10 is provided on the rotating sleeve 711, and the locking device 10 includes a locking plate 101, a locking pin 102, a driving block 103 and a second nut 104. The locking plate 101 is embedded in the rotating sleeve 711, and the second nut 104 is installed on the rotating sleeve 711. One end of the locking pin 102 successively passes through the second nut 104 and the rotating sleeve 711 and is rotatably connected to the locking plate 101, and the locking pin 102 is threadedly connected to the second nut 104, and the driving block 103 is installed at the other end of the locking pin 102.

[0111] By providing the locking device 10, the rubber sleeve 532 can further limit the position of the rotating sleeve 711, thereby improving the axial limit of the mounting platform 7;

[0112] When the rotating sleeve 711 needs to be rotated, the locking pin 102 is first screwed through the driving block 103, and the locking pin 102 acts with the second nut 104 to drive the locking plate 101 to separate from the threaded sleeve 53, so that the rotating sleeve 711 can be rotated; when limiting, the driving block 103 is rotated in the reverse direction, and the locking pin 102 pushes the locking plate 101 to squeeze the threaded sleeve 53, thereby assisting in limiting the rotating sleeve 711.

[0113] The locking plate 101 is an arc-shaped plate, which is adapted to the surface curvature of the threaded sleeve 53, and a rubber pad is correspondingly provided on the side of the locking plate 101 facing the threaded sleeve 53;

[0114] As an optional mode of this embodiment, the limiting member 65 includes a U-shaped handle 651, a positioning pin 652 and a first nut 653. A fixing sleeve 631 is fixed to the top of the main gear 63, and the fixing sleeve 631 is sleeved on the driving shaft 62. The first nut 653 is installed on the fixing sleeve 631. The positioning pin 652 passes through the first nut 653 and the fixing sleeve 631 in sequence, and the positioning pin 652 is threadedly connected with the first nut 653. Three jacks 621 are provided on the corresponding driving shaft 62.

[0115] When the positioning pin 652 is inserted into the insertion hole 621 from bottom to top, the main gear 63 is assembled with the first slave gear and the second slave gear in sequence, and the driving shaft 64 is assembled with the bar frame.

[0116] The U-shaped handle 651 is twisted to drive the positioning pin 652 to rotate and interact with the first nut 653 to move out of or into the corresponding insertion hole 621 to achieve unlocking or limiting connection;

[0117] When the locking device 10 is aligned with the stopper 65 and the rotating sleeve 711 needs to be driven to rotate, please refer to Figure 7 , when the positioning pin 652 moves out of the corresponding insertion hole 621, continue to twist the U-shaped handle 651 to make it move out of the first nut 653 for a section, and when the moving main gear 63 is engaged with the rotating member 9 (the second slave gear), the U-shaped handle 651 is sleeved on the driving block 103, and the U-shaped handle 651 is rotated in the opposite direction, and the U-shaped handle 651 drives the driving block 103 to rotate accordingly, and the corresponding U-shaped handle 651 drives the positioning pin 652 to act on the first nut 653, so that the positioning pin 652 moves toward the corresponding insertion hole 621 and is inserted into the insertion hole 621, and the driving block 103 drives the locking pin 102 to rotate and act on the second nut 104, so that the locking pin 102 drives the locking plate 101 to separate from the threaded sleeve 53, and the operation is more convenient;

[0118] When the locking plate 101 is separated from the threaded sleeve 53 , the U-shaped handle 651 is separated from the driving block 103 , and the U-shaped handle 651 is continuously twisted to insert the positioning pin 652 into the corresponding insertion hole 621 .

[0119] As another optional method of this embodiment, the drive shaft 62 does not have the insertion hole 621, and a stop block is provided at the end of the positioning pin 652, and the stop block abuts against the drive shaft 62 to achieve the connection between the main gear 63 and the drive shaft 62. A rubber block is provided on the stop block to improve the stability of the connection.

[0120] A method for calibrating a volatile organic compound differential absorption lidar system

[0121] See also Fig.10 The present invention also provides a volatile organic compound differential absorption laser radar system calibration method, using the volatile organic compound differential absorption laser radar system calibration device, comprising the following steps:

[0122] S1. Place the calibration tube 1 and the laser radar 2 on the same axis in an open area, with a preset distance between them (such as 80m, 100m, etc.), start the laser radar 2, adjust the laser wavelength in turn, and observe the echo signal. If the echo signal has a bump or mutation, adjust the position of the calibration tube 1 to make the echo signal corresponding to each laser wavelength balanced and stable;

[0123] S2, releasing the target gas to be measured through the small hole below the calibration cylinder 1, and monitoring the concentration change of the target gas in real time through the probe of the point measurement device 3;

[0124] S3, start the laser radar 2 to detect and invert the real-time concentration of the target gas to be measured;

[0125] S4, perform calibration calculation, first release the target gas volume, the concentration change monitored by the point measurement device 3, and accurately calculate the curve of the gas concentration change in the calibration cylinder 1 over time according to the diffusion theory;

[0126] S5. The laser radar 2 inverts the target gas concentration measured at the preset distance, and uses the concentration curve of the calibration tube 1 calculated in S4 as the calibration gold standard to calibrate the laser radar 2.

[0127] For the laser radar 2 that can measure the differential absorption of multiple gases, the accuracy of detecting each gas can be precisely calibrated by releasing different gases each time.

[0128] The use of the calibration tube 1 can limit the diffusion of the target gas, and the point measurement device 3 plus the controlled released gas volume can accurately detect the concentration change of the actual target gas. Moreover, the laser radar 2 is a remote sensing instrument with distance resolution. The actual inversion concentration is the average concentration within the distance resolution. The calibration tube 1 can accurately reflect the accuracy of its detection within a distance resolution at the designed distance.

[0129] Compared with the calibration scheme using a gas absorption cell, calibrating the entire laser radar 2 directly in the atmospheric environment is more scientific and has operability and repeatability in the actual generation and deployment of the laser radar 2; and by providing a matte velvet layer 11 on the inner lining of the calibration tube 1, multiple scattering of lasers is reduced to improve accuracy.

[0130] Among them, the echo signal in S1 has bulges or mutations. The bulge refers to isolated peak bulges or continuous block bulges of the echo signal, and the mutation refers to sudden increase, sudden decrease, frequency jump, etc. of the intensity of the echo signal.

[0131] Among them, the specific structure of the volatile organic compound differential absorption laser radar system calibration device refers to the above-mentioned embodiment. Since the volatile organic compound differential absorption laser radar system calibration method adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0132] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A volatile organic compound differential absorption laser radar system calibration device, characterized in that: include: calibration cylinder, lidar and point measurement equipment and two stands; A matte fleece layer is installed inside the calibration cylinder, an exhaust hole is opened at the bottom of the calibration cylinder, and the calibration cylinder is in the shape of a truncated cone; The calibration cylinder and the laser radar are respectively mounted on the two brackets; The detection end of the point-type measuring device is suspended below the exhaust hole; When in use, the two brackets are placed at a preset distance, and the center of the calibration cylinder and the output end of the laser radar are located on the same axis.

2. The volatile organic compound differential absorption laser radar system calibration device according to claim 1, characterized in that: The volatile organic compound differential absorption laser radar system calibration device also includes two laser spotlights, which are correspondingly mounted on the bracket through a mounting plate, and the output ends of the two laser spotlights are arranged in opposite directions.

3. The volatile organic compound differential absorption laser radar system calibration device according to claim 1, characterized in that: The calibration cylinder is made of plastic.

4. The volatile organic compound differential absorption laser radar system calibration device according to claim 2, characterized in that: The bracket comprises a base, a lifting assembly and a mounting platform, the lifting assembly is mounted on the base, the mounting platform comprises a mounting box, a slide, a moving part and a plurality of slide bars, a plurality of the slide bars are installed inside the mounting box at intervals, the slide is sleeved on the slide bars, the moving part is used to drive the slide to move along the slide bars, and the mounting box is rotatably mounted on the output end of the lifting assembly; The calibration tube and the laser radar are respectively mounted on the corresponding slides, and the laser spotlight is mounted on the slide via the mounting plate.

5. The volatile organic compound differential absorption laser radar system calibration device according to claim 4, characterized in that: The lifting assembly includes a threaded shaft, a rotating member, a threaded sleeve and a limit rod. The threaded shaft is rotatably mounted on the top of the base. The threaded sleeve is threadedly connected to the threaded shaft. The limit rod is installed on the base and arranged adjacent to the threaded shaft. The threaded sleeve is slidably connected to the limit rod via a connecting ear. The rotating member is used to drive the threaded shaft to rotate.

6. The volatile organic compound differential absorption laser radar system calibration device according to claim 5, characterized in that: A rotating sleeve is installed at the bottom of the installation box, and the rotating sleeve is arranged on the top of the threaded sleeve. The volatile organic compound differential absorption laser radar system calibration device also includes a rotating member, and the rotating member is used to drive the rotating sleeve to rotate.

7. The volatile organic compound differential absorption laser radar system calibration device according to claim 6, characterized in that: The volatile organic compound differential absorption laser radar system calibration device also includes a driving device, which includes a motor, a driving shaft, a main gear, a driving shaft and a limiter, wherein the motor is mounted on the base, the driving shaft is mounted on the output end of the motor, the main gear is sleeved on the driving shaft, and the main gear is detachably mounted on the driving shaft through the limiter; The rotating member is the first slave gear, which is installed on the threaded shaft. The rotating member is the second slave gear, which is installed on the rotating sleeve. When the rotating member is working, the main gear is engaged with the rotating member. When the rotating member is working, the main gear is engaged with the rotating member.

8. The volatile organic compound differential absorption laser radar system calibration device according to claim 7, characterized in that: The movable part is a bar frame, which is installed at the bottom of the slide, and a circular hole is opened on the mounting platform corresponding to the position of the movable part. The driving device also includes a driving shaft, which is eccentrically installed on the top of the main gear and is located below the circular hole.

9. The volatile organic compound differential absorption laser radar system calibration device according to claim 7, characterized in that: A rubber sleeve is arranged between the rotating sleeve and the threaded sleeve.

10. A volatile organic compound differential absorption laser radar system calibration method, characterized in that: Using the volatile organic compound differential absorption laser radar system calibration device according to any one of claims 1 to 9, comprising the following steps: S1. Place the calibration tube and laser radar on the same axis in an open area, with a preset distance between them, start the laser radar, adjust the laser wavelength in sequence, and observe the echo signal. If the echo signal has a bump or mutation, adjust the position of the calibration tube to make the echo signal corresponding to each laser wavelength balanced and stable; S2. Release the target gas to be measured through the small hole at the bottom of the calibration cylinder, and monitor the concentration change of the target gas in real time through the probe of the point measurement device; S3, start the laser radar to detect and invert the real-time concentration of the target gas to be measured; S4. Perform calibration calculations. First, release the target gas volume, and measure the concentration changes monitored by the point measurement device. According to the diffusion theory, accurately calculate the curve of the gas concentration in the calibration cylinder over time. S5. The laser radar inverts the target gas concentration measured at the preset distance, and uses the calibration cylinder concentration curve calculated in S4 as the calibration gold standard to calibrate the laser radar.

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