A gimbal scanning laser combustible gas detection method and device thereof

Abstract

The application discloses a gimbal scanning type laser combustible gas detection method and equipment, and relates to the technical field of gas detection. The detection equipment comprises an explosion-proof main body, a gimbal scanning module, a laser detection module and a camera monitoring module, and the explosion-proof main body is internally provided with a horizontal transmission cavity, a vertical transmission cavity, a visible light cavity and a laser cavity. The gimbal scanning module comprises a horizontal shaft driving unit, a pitch shaft driving unit and a roll shaft driving unit, and the roll shaft driving unit drives the laser detection module and the camera monitoring module to swing in a horizontal longitudinal transverse roll rotation. The detection method generates a concentration data set through global scanning, performs local encryption scanning at a self-adaptive reduced speed after exceeding the standard, solves a concentration gradient field and dynamically adjusts a stepping interval, calculates a three-dimensional coordinate of a leakage source after compensation in combination with meteorological parameters and triggers snapshot, and realizes three-axis linkage scanning, self-adaptive variable speed detection and three-dimensional accurate positioning of the leakage source.

Description

Technical Field

[0001] This invention relates to the field of gas detection technology, and in particular to a pan-tilt-zoom laser combustible gas detection method and device. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] In the fields of natural gas extraction, transportation, and chemical production, methane and methane-containing gas leak monitoring is a core means of ensuring production safety and preventing explosions and fires. The monitoring range, detection accuracy, anti-interference capability, and automation level of combustible gas detectors directly affect the timeliness and reliability of leak warnings. Currently, most combustible gas detectors on the market adopt electrochemical and infrared detection principles, mainly consisting of a detection probe, a signal processing unit, an alarm unit, and a power supply unit. Their working principle involves the detection probe sensing the concentration of combustible gas in the environment, converting the concentration signal into an electrical signal, which is then analyzed by the signal processing unit. If the concentration exceeds a preset threshold, the alarm unit is triggered. The power supply unit provides power to the entire device.

[0004] In recent years, PTZ-based laser combustible gas detectors, as an emerging leak detection technology, have been gradually applied in scenarios such as liquefied natural gas receiving stations and natural gas stations. These detectors mount a laser gas detector on a PTZ platform, using the platform's horizontal rotation and pitch oscillation to achieve multi-point scanning and inspection of the monitored area. However, existing PTZ-based detectors generally only have two rotational degrees of freedom: horizontal (yaw) and pitch (tilt). While they can achieve 360° horizontal and a certain pitch angle scanning coverage, in complex spatial layouts of stations, the lack of roll attitude adjustment means the laser beam cannot illuminate the target reflective surface at the optimal incident angle, resulting in weak echo signals in some areas and unreliable detection data. Furthermore, while existing PTZ-based detectors can detect the presence of leaking gas, they can only provide concentration alarm information and cannot accurately calculate the specific coordinates of the leak source in three-dimensional space. Even when combined with video surveillance, they can only achieve an "alarm + recording" working mode; leak point investigation still requires manual on-site confirmation, resulting in low efficiency. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned shortcomings by providing a pan-tilt-zoom (PTZ) scanning laser combustible gas detection method and device.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a pan-tilt-zoom laser combustible gas detection method, comprising the following steps: The control gimbal scanning module drives the laser detection module to perform a full-area scan of the target area at the first scanning speed, and simultaneously collects the gimbal attitude coordinates and methane concentration at each scanning point to generate a full-area concentration dataset. When the methane concentration at a certain scanning point is detected to be greater than a preset threshold, the concentration deviation is calculated, and a second scanning speed less than the first scanning speed is calculated based on the concentration deviation. The PTZ scanning module is then controlled to perform a local scan within the scanning window centered on the point exceeding the threshold at the second scanning speed, while simultaneously acquiring a local concentration dataset. The two-dimensional concentration gradient field is solved based on the local concentration dataset. The scanning angle step interval of the gimbal is dynamically adjusted according to the gradient amplitude. The gas diffusion offset is compensated by combining real-time environmental meteorological parameters. The three-dimensional coordinates of the leakage source are calculated by fusing gimbal attitude information and laser ranging data. The camera monitoring module is triggered to capture on-site images simultaneously.

[0007] Furthermore, in the global scanning detection, the gimbal scanning module completes a global traversal along a preset trajectory; Furthermore, the global concentration dataset includes the horizontal angle, pitch angle, roll angle, and methane concentration of each point's gimbal.

[0008] Furthermore, the concentration deviation is the difference between the measured methane concentration at the point exceeding the standard and a preset threshold. ; The second scanning speed is calculated using an inverse proportional nonlinear speed regulation model. The speed regulation model is specifically as follows:

[0009] in, This is the minimum scanning rate allowed by the pan-tilt unit. To calibrate the speed regulation coefficient on site, This represents the concentration deviation.

[0010] Furthermore, the local scan is a reciprocating encrypted raster scan, and the methane concentration at each scan point in the local concentration dataset is correlated with the corresponding three-dimensional attitude vector. , , ) Associated storage, the scroll angle Used to mark the measurement posture of each scanning point under different beam incident directions; The two-dimensional concentration gradient field is solved using the central difference method based on a local concentration dataset. The formulas for calculating the gradient components and gradient magnitude are as follows: Horizontal gradient:

[0011] Pitch gradient:

[0012] Gradient magnitude:

[0013] The pan-tilt scanning angle step interval The calculation is as follows:

[0014] in, The horizontal angle of the gimbal. For the tilt angle of the gimbal, This represents the angular difference between two adjacent sets of sampling points in the horizontal direction. This represents the angle difference between two adjacent sets of sampling points in the pitch direction. For gimbal attitude The methane optical path concentration values ​​collected at the sampling point. This represents the gradient component of methane concentration along the horizontal direction. This represents the gradient component of methane concentration along the pitch direction. This is the sampling calibration constant.

[0015] Furthermore, the real-time environmental meteorological parameters include real-time wind speed and wind direction; By substituting wind speed and direction parameters into the Gaussian smoke cloud diffusion model, offset compensation is performed on the two-dimensional concentration gradient field obtained from the local concentration dataset to obtain the corrected two-dimensional concentration gradient field. The three-dimensional coordinates of the leakage source are then calculated based on the corrected two-dimensional concentration gradient field.

[0016] Furthermore, the formula for calculating the three-dimensional coordinates of the leakage source is as follows:

[0017] in, For laser detection distance, , , These are the three-dimensional spatial coordinates of the leakage source; The roll angle This is used to perform horizontal calibration on the on-site images captured by the camera monitoring module, so that the horizontal reference direction of the captured images is consistent with the spatial orientation of the three-dimensional coordinates of the leakage source; When the pitch angle When the angle is close to ±90°, the roll angle is used in the calculation of the three-dimensional coordinates of the leakage source. For the horizontal angle Kinematic compensation is performed to address the degradation of degrees of freedom.

[0018] Furthermore, it also includes: A complete three-dimensional concentration field is generated by mapping the modified two-dimensional concentration gradient field. The methane leakage flux is obtained by combining real-time wind speed integral calculation. Based on the leakage flux value, four levels of leakage risk are divided, and corresponding local audible and visual warnings and cloud-based remote warning signals are output. If the methane concentration at all points within the scanning window remains below the preset threshold for 30 consecutive seconds, the PTZ scanning module automatically switches to the first scanning speed and resumes full-area cyclic scanning.

[0019] A pan-tilt-zoom (PTZ) scanning laser combustible gas detection device includes an explosion-proof main body, a PTZ scanning module, a laser detection module, and a camera monitoring module. The explosion-proof main body is internally divided into multiple independent cavities, including a horizontal drive cavity, a vertical drive cavity, a visible light cavity, and a laser cavity. The PTZ scanning module includes a horizontal axis drive unit located in the horizontal drive cavity and a pitch axis drive unit located in the vertical drive cavity. The laser detection module and the camera monitoring module are respectively located in the laser cavity and the visible light cavity. The device also includes: A rolling shaft drive unit is disposed inside the explosion-proof body. The rolling shaft drive unit is connected to the laser detection module and the camera monitoring module, and drives the laser detection module and the camera monitoring module to swing left and right around the horizontal longitudinal direction.

[0020] Furthermore, the rolling shaft drive unit includes a spherical body and a spherical cavity within the rolling transmission cavity and connected to the horizontal transmission cavity and the vertical transmission cavity, respectively. The spherical cavity is rolled and adapted to the spherical body. A rotating shaft is horizontally inserted through the spherical cavity along its longitudinal direction. The rotating shaft extends horizontally within the spherical body. A worm gear is provided on the rotating shaft and in part of the spherical body. A worm driven by a motor is adapted to be provided on the worm gear.

[0021] Furthermore, a wire-passing hole is provided on the vertical transmission cavity corresponding to the center of the horizontal transmission cavity, and a limiting block for wire passing is provided in the wire-passing hole. An arc groove is provided on the spherical body, and the limiting block moves relative to the horizontal transmission cavity and the vertical transmission cavity within the arc groove and follows the relative movement of the horizontal transmission cavity and the vertical transmission cavity without interfering with the arrangement of the cable.

[0022] The beneficial effects of this invention are reflected in: (1) The present invention adopts a three-level variable speed scanning strategy of full-area coarse scanning, speed reduction for exceeding the standard, and local encryption. In the non-leaking area, it quickly traverses at a high speed, and in the leaking area, it automatically reduces the speed and performs reciprocating encryption grating scanning. At the same time, it dynamically adjusts the scanning step interval according to the concentration gradient amplitude, thereby achieving the optimal balance between monitoring efficiency and accuracy; (2) This invention integrates gimbal attitude information and laser ranging data, combines Gaussian smoke cloud diffusion model for meteorological parameter compensation, accurately calculates the three-dimensional coordinates of the leakage source, and simultaneously triggers the camera monitoring module to capture on-site images, thus realizing integrated leakage source tracing; (3) The present invention uses the roll angle to perform horizontal calibration on the on-site images captured by the camera monitoring module, so that the horizontal reference direction of the captured image is consistent with the spatial orientation of the three-dimensional coordinates of the leakage source, providing a more intuitive and accurate visual basis for on-site investigation by staff; (4) This invention adds a rolling axis drive unit to the existing horizontal and pitch axes, enabling the gimbal scanning module to have three rotational degrees of freedom: horizontal rotation, pitch swing, and roll rotation around the optical axis. The three-axis linkage can realize the arbitrary orientation of the laser beam in three-dimensional space, fundamentally eliminating the monitoring blind zone and solving the technical problem of limited scanning dimensions of existing dual-axis gimbals. Attached Figure Description

[0023] Figure 1 This is a flowchart of the present invention; Figure 2 This is a three-dimensional structural diagram of a pan-tilt scanning laser combustible gas detection device according to the present invention; Figure 3 This is a half-sectional view of a pan-tilt scanning laser combustible gas detection device according to the present invention; Figure 4 This is a partially enlarged view of a pan-tilt-zoom laser combustible gas detection device according to the present invention.

[0024] In the picture: 1. Explosion-proof main body; 2. Laser detection module; 3. Camera monitoring module; 4. Horizontal transmission cavity; 5. Vertical transmission cavity; 6. Visible light cavity; 7. Laser cavity; 8. Spherical body; 9. Spherical cavity; 10. Rotating shaft; 11. Worm gear; 12. Worm; 13. Wire through hole; 14. Limiting block; 15. Arc groove. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] like Figure 2 , Figure 3As shown, the present invention provides a pan-tilt scanning laser combustible gas detection device, including an explosion-proof main body 1, a pan-tilt scanning module, a laser detection module 2, and a camera monitoring module 3.

[0027] The explosion-proof body 1 is made of 304 or 316L stainless steel, possessing excellent corrosion resistance and impact resistance. The explosion-proof body 1 is internally divided into multiple independent cavities, specifically including a horizontal transmission cavity 4, a vertical transmission cavity 5, a visible light cavity 6, and a laser cavity 7. These cavities are isolated from each other by explosion-proof mating surfaces, ensuring that in the event of an internal explosion in any cavity, flames and high-temperature gases will not enter adjacent cavities through the mating surfaces. The explosion-proof markings for the explosion-proof body 1 are Ex db IIC T6 Gb and Extb IIIC T80℃ Db, with a protection rating of IP66 / IP68.

[0028] A horizontal axis drive unit (preferably a horizontal stepper motor) is installed in the horizontal transmission cavity 4 to drive the laser detection module 2 and the camera monitoring module 3 to rotate continuously 360° horizontally around the vertical direction. A pitch axis drive unit (preferably a pitch stepper motor) is installed in the vertical transmission cavity 5 to drive the laser detection module 2 and the camera monitoring module 3 to pitch oscillate from -45° to +90° around the horizontal direction.

[0029] The laser detection module 2 is housed within the laser cavity 7 and is designed based on the principle of Tunable Laser Absorption Spectroscopy (TDLAS). It employs a distributed feedback laser diode (DFB laser) as the light source to emit a detection laser and receive reflected light to detect the concentration of the target gas (such as methane). The detection distance of the laser detection module 2 is 0–150 m (expandable to 200 m), the detection range is 0–50000 ppm·m, the detection error is ≤±5%, and the response time is <0.1 s. The optical window uses high-transparency, anti-fouling coated glass to effectively prevent dust and moisture adhesion.

[0030] The video monitoring module 3 is located inside the visible light cavity 6. It is a high-definition industrial camera unit (preferably 2 megapixels, lens focal length 16mm) used to acquire on-site video images. The night vision distance is ≥50m, and it supports low-light color imaging. It has a built-in dustproof and waterproof protective cover with a protection level of IP67.

[0031] Detailed Implementation of the Rolling Shaft Drive Unit like Figure 3 and Figure 4 As shown, the rolling shaft drive unit is located inside the explosion-proof body 1 and is connected to the laser detection module 2 and the camera monitoring module 3 for driving the laser detection module 2 and the camera monitoring module 3 to roll and rotate horizontally.

[0032] In a preferred embodiment, the rolling shaft drive unit includes a spherical body 8 and a spherical cavity 9. The spherical cavity 9 is rolled and adapted to the spherical body 8 to realize multi-degree-of-freedom motion transmission in a ball-joint manner. A rotating shaft 10 is horizontally inserted through the spherical cavity 9 along its longitudinal direction, and the rotating shaft 10 extends horizontally into the spherical body 8. A worm gear 11 is fitted onto the portion of the rotating shaft 10 located inside the spherical body 8, and a worm 12 driven by a motor is adapted to be mounted on the worm gear 11.

[0033] When the motor drives the worm gear 12 to rotate, the worm gear 12 drives the worm wheel 11 to rotate. The worm wheel 11, through the rotating shaft 10, drives the laser detection module 2 and the camera monitoring module 3, which are connected to the spherical cavity 9, to roll and oscillate relative to the spherical body 8 in the horizontal direction. The worm gear transmission method has a self-locking characteristic, which can maintain the current rolling posture in the event of a power failure, thereby improving the safety of the equipment.

[0034] The rotational speed of the rolling shaft drive unit is ≤10° / s, the positioning accuracy is ≤0.05°, and the roll angle range is preferably ±45° (which can be extended to ±90° according to actual needs).

[0035] The rotor shaft of the rolling shaft drive unit is provided with a cylindrical explosion-proof joint surface at the point where it passes through the housing. The joint length L≥15mm and the maximum gap ic≤0.15mm ensures that the explosion-proof requirements are met while the shaft rotates.

[0036] Specific implementation methods of the trace routing structure like Figure 3 As shown, since the laser detection module 2 and the camera monitoring module 3 need to follow the rolling axis drive unit to rotate horizontally, the cable cannot be routed from the outside and must pass through the center of rotation.

[0037] A wire-passing hole 13 is provided at the center of the vertical transmission cavity 5, corresponding to the center of the horizontal transmission cavity 4. A limiting block 14 for wire passing is provided inside the wire-passing hole 13. An arc groove 15 is provided on the spherical body 8, and the limiting block 14 can move relative to the horizontal transmission cavity 4 and the vertical transmission cavity 5. When the horizontal transmission cavity 4 and the vertical transmission cavity 5 move relative to each other, the limiting block 14 slides along the arc groove 15 to ensure that the cable is not interfered with or excessively bent during the movement.

[0038] It should be noted that at the outlet of the horizontal transmission cavity 4 and the intersection with the spherical body 8, the cable has a redundant bend (S-shaped bend) to accommodate the reciprocating horizontal rotation of ±45° and prevent the cable from fatigue breaking.

[0039] Complete workflow of detection method like Figure 1 As shown, the present invention provides a pan-tilt-zoom (PTZ) scanning laser combustible gas detection method, which specifically includes the following steps: Step S1: Device initialization and self-test After the equipment is powered on, the power supply module provides stable power to each module, and the control and early warning module starts a self-test to check the working status of each functional module.

[0040] Step S2: Global Scan Detection The control and early warning module controls the gimbal scanning module to drive the laser detection module 2 to perform a full-area traversal scan of the target area along a preset trajectory at a first scanning speed (e.g., 10° / s). Simultaneously, the gimbal attitude coordinates (horizontal angle) of each scanning point are acquired. Pitch angle Roll angle Combine methane concentration with methane concentration to generate a global concentration dataset.

[0041] Step S3: Leakage Assessment The control and early warning module determines in real time whether the methane concentration at each scanning point exceeds a preset threshold. If all locations are within acceptable limits, continue with the full-area scan and continuously upload the data to the cloud platform.

[0042] Step S4: Adaptive speed reduction and local encrypted scanning When the methane concentration at a certain scanning point is detected At that time, the control and early warning module calculates the concentration deviation. The second scanning speed is calculated using an inverse proportional nonlinear speed regulation model. (in This is the minimum scanning rate of the pan-tilt unit, such as 1° / s; (To calibrate the speed regulation coefficient on site).

[0043] Control the PTZ scanning module to scan at the second speed A reciprocating encrypted raster scan is performed within a scanning window centered on the point exceeding the standard. The horizontal and vertical angle ranges of the scanning window vary with concentration deviation. Positive increase – the greater the concentration deviation, the larger the monitoring area covered by the window.

[0044] Collect local concentration datasets, including methane concentrations at each scan point and their corresponding 3D attitude vectors. Associated storage.

[0045] Step S5: Solving the concentration gradient field and adaptive step adjustment Based on a local concentration dataset, the two-dimensional concentration gradient field is solved using the central difference method: Horizontal gradient:

[0046] Pitch gradient:

[0047] Gradient magnitude:

[0048] The gimbal scanning angle step interval is dynamically adjusted based on the gradient magnitude. The larger the gradient (i.e., the more drastic the concentration change), the smaller the scan step interval and the higher the scan density, thus achieving a fine characterization of the leakage source boundary.

[0049] Step S6: Meteorological parameter compensation and three-dimensional positioning Real-time wind speed and direction data are acquired using meteorological sensors. The wind speed and direction parameters are then substituted into the Gaussian smoke mass diffusion model to perform offset compensation on the two-dimensional concentration gradient field obtained in step S5, resulting in a corrected two-dimensional concentration gradient field that eliminates the positioning deviation caused by wind on the air mass diffusion.

[0050] The Gaussian plume model is based on the normal distribution assumption of statistical theory to estimate the diffusion pattern of gases. This model treats the instantaneously released pollutant plume as a plume with a Gaussian (normal) distribution in both horizontal and vertical directions, simulating the temporal and spatial concentration distribution changes of the pollutant plume.

[0051] Specifically, S61: Obtain meteorological parameters Real-time wind speed is obtained through meteorological sensors. and wind direction The meteorological sensor can be integrated into the explosion-proof body 1, or it can access data from the on-site meteorological station via a wireless communication unit.

[0052] S62: Constructing a Gaussian smoke puff diffusion model A Gaussian smoke cloud diffusion model coordinate system is established with the location of the exceeding standard (i.e., the suspected leak source) as the origin and the downwind direction as the x-axis. Wind speed is then used as the coordinate system. Substituting the average wind speed into the model formula .

[0053] S63: Coordinate Transformation and Data Mapping The gimbal attitude coordinates of each measurement point in the local concentration dataset and laser ranging The coordinates are converted to the model coordinate system using the above coordinate transformation formula. , and the corresponding measured concentration value Related.

[0054] S64: Model Parameter Inversion and Concentration Field Reconstruction Using the local concentration dataset as a constraint, the diffusion parameters in the Gaussian smoke model are... , Perform inversion to solve:

[0055] To find the optimal solution, we need to minimize the sum of squared errors between the model-predicted concentration and the measured concentration. and .

[0056] S65: Generate a modified two-dimensional concentration gradient field Using the optimal diffusion parameters obtained from the inversion, the theoretical concentration distribution at each spatial point within the scanning window is recalculated based on the Gaussian smoke model, generating a corrected two-dimensional concentration gradient field. .

[0057] S66: Eliminate wind positioning deviation The corrected concentration gradient field incorporates the influence of wind on air mass diffusion into the model. The direction of the maximum gradient amplitude, after inverse coordinate transformation, points to the true spatial location of the leakage source, thereby eliminating the air mass drift deviation caused by wind.

[0058] Based on the modified two-dimensional concentration gradient field, gimbal attitude information (horizontal angle) is fused. Pitch angle ) and laser ranging data Calculate the three-dimensional coordinates of the leakage source:

[0059] At the same time, utilize the rolling angle The images captured by camera monitoring module 3 are horizontally calibrated to ensure that the horizontal reference direction of the captured images is consistent with the spatial orientation of the three-dimensional coordinates of the leakage source. When the pitch angle... When the angle is close to ±90° (i.e., the gimbal is nearly perpendicular to the zenith or the ground), use the roll angle. For horizontal angle Kinematic compensation is performed to compensate for the degradation of degrees of freedom, ensuring accurate positioning results across the entire attitude range.

[0060] The camera monitoring module 3 is triggered to capture high-definition images of the scene and pushes the leakage concentration data, captured images, and early warning information to the cloud platform and staff mobile devices through the wireless communication unit.

[0061] Step S7: Risk Classification and Early Warning Output A complete three-dimensional concentration field is generated by mapping a modified two-dimensional concentration gradient field, and the methane leakage flux is obtained by combining real-time wind speed integral calculation. (Unit: kg / s). Leakage risk is classified into four levels based on leakage flux: Level 1 (Low Risk): Only record data; Level 2 (Medium Risk): Output local audible and visual warnings; Level 3 (High Risk): It outputs local audible and visual warnings plus remote cloud-based warnings; Level 4 (Extremely High Risk): It outputs local sound and light warnings, cloud-based remote warnings, and a coordinated emergency response mechanism.

[0062] Step S8: Resume Scan If the methane concentration at all points within the scanning window remains below the preset threshold for 30 consecutive seconds... This indicates that the leak has been eliminated or the gas cloud has dissipated. The PTZ scanning module automatically switches to the first scanning speed, resumes full-area cyclic scanning, and enters the next monitoring cycle.

[0063] Further optimization of the direct-drive torque motor solution: A hollow brushless DC torque motor is used, with the stator fixed to the upper surface of the vertical transmission cavity 5, and the rotor output end directly fixedly connected to the U-shaped bracket. This solution eliminates intermediate transmission links, thus eliminating backlash, resulting in higher positioning accuracy (up to 0.02°) and faster response speed.

[0064] Harmonic speed reduction transmission scheme: Using a harmonic speed reducer as the speed reduction transmission mechanism for the rolling shaft has the advantages of small size, large transmission ratio and small backlash, and is suitable for application scenarios with higher requirements for rolling accuracy.

[0065] The rolling shaft drive unit may not have a separate rolling transmission cavity. Instead, the rolling shaft motor can be built into the vertical transmission cavity 5 (using a nested structure, with the rolling shaft motor installed inside the vertical shaft sleeve) to reduce the overall volume and the number of cavities.

[0066] The wireless communication unit can adopt a 4G Cat.1 module, a 5G module, or a 5G+LoRa dual-mode communication module. Among them, 5G enables high-speed video and image data transmission, while LoRa enables low-power concentration data and device status data transmission, adapting to remote sites and pipeline network scenarios without 4G / 5G signals.

[0067] In addition to using a distributed feedback laser diode (DFB laser), the laser source of the laser detection module 2 can also use a VCSEL laser diode, which has higher beam quality and lower power consumption.

[0068] It should be noted that the specific embodiments and alternatives described above are merely illustrative and do not limit the scope of protection of this invention. In practical applications, those skilled in the art can select some or all of the technical features to achieve the purpose of this invention according to actual needs, and no limitations are imposed here.

[0069] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0070] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0071] Additionally, "multiple" refers to two or more.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pan-tilt-zoom (PTZ) scanning laser combustible gas detection method, characterized in that, Includes the following steps: The control gimbal scanning module drives the laser detection module (2) to perform a full-area scanning detection of the target area at the first scanning speed, and simultaneously collects the gimbal attitude coordinates and methane concentration at each scanning point to generate a full-area concentration dataset. When the methane concentration at a certain scanning point is detected to be greater than a preset threshold, the concentration deviation is calculated, and a second scanning speed less than the first scanning speed is calculated based on the concentration deviation. The PTZ scanning module is then controlled to perform a local scan within the scanning window centered on the point exceeding the threshold at the second scanning speed, while simultaneously acquiring a local concentration dataset. The two-dimensional concentration gradient field is solved based on the local concentration dataset. The scanning angle step interval of the PTZ is dynamically adjusted according to the gradient amplitude. The gas diffusion offset is compensated by combining real-time environmental meteorological parameters. The three-dimensional coordinates of the leakage source are calculated by integrating the PTZ attitude information and laser ranging data. The camera monitoring module (3) is triggered to capture on-site images.

2. The pan-tilt-zoom laser combustible gas detection method according to claim 1, characterized in that: In the full-domain scanning detection, the gimbal scanning module completes full-domain traversal along a preset trajectory; Furthermore, the global concentration dataset includes the horizontal angle, pitch angle, roll angle, and methane concentration of each point's gimbal.

3. The pan-tilt-zoom laser combustible gas detection method according to claim 2, characterized in that: The concentration deviation is the difference between the measured methane concentration at the point exceeding the standard and the preset threshold. ; The second scanning speed is calculated using an inverse proportional nonlinear speed regulation model. The speed regulation model is specifically as follows: in, This is the minimum scanning rate allowed by the pan-tilt unit. To calibrate the speed regulation coefficient on site, This represents the concentration deviation.

4. The pan-tilt-zoom laser combustible gas detection method according to claim 3, characterized in that: The local scan is a reciprocating encrypted raster scan, and the methane concentration at each scan point in the local concentration dataset is correlated with the corresponding three-dimensional attitude vector. , , ) Associated storage, the scroll angle Used to mark the measurement posture of each scanning point under different beam incident directions; The two-dimensional concentration gradient field is solved using the central difference method based on a local concentration dataset. The formulas for calculating the gradient components and gradient magnitude are as follows: Horizontal gradient: Pitch gradient: Gradient magnitude: The pan-tilt scanning angle step interval The calculation is as follows: in, The horizontal angle of the gimbal. For the tilt angle of the gimbal, This represents the angular difference between two adjacent sets of sampling points in the horizontal direction. This represents the angle difference between two adjacent sets of sampling points in the pitch direction. For gimbal attitude The methane optical path concentration values ​​collected at the sampling point. This represents the gradient component of methane concentration along the horizontal direction. This represents the gradient component of methane concentration along the pitch direction. This is the sampling calibration constant.

5. The pan-tilt-zoom laser combustible gas detection method according to claim 4, characterized in that: The real-time environmental meteorological parameters include real-time wind speed and wind direction; By substituting wind speed and direction parameters into the Gaussian smoke cloud diffusion model, offset compensation is performed on the two-dimensional concentration gradient field obtained from the local concentration dataset to obtain the corrected two-dimensional concentration gradient field. The three-dimensional coordinates of the leakage source are then calculated based on the corrected two-dimensional concentration gradient field.

6. The pan-tilt-zoom laser combustible gas detection method according to claim 5, characterized in that, The formula for calculating the three-dimensional coordinates of the leakage source is: in, For laser detection distance, , , These are the three-dimensional spatial coordinates of the leakage source; The roll angle Used to perform horizontal calibration on the on-site images captured by the camera monitoring module (3) so that the horizontal reference direction of the captured images is consistent with the spatial orientation of the three-dimensional coordinates of the leakage source; When the pitch angle When the angle is close to ±90°, the roll angle is used in the calculation of the three-dimensional coordinates of the leakage source. For the horizontal angle Kinematic compensation is performed to address the degradation of degrees of freedom.

7. The pan-tilt-zoom laser combustible gas detection method according to claim 6, characterized in that, Also includes: A complete three-dimensional concentration field is generated by mapping the modified two-dimensional concentration gradient field. The methane leakage flux is obtained by combining real-time wind speed integral calculation. Based on the leakage flux value, four levels of leakage risk are divided, and corresponding local audible and visual warnings and cloud-based remote warning signals are output. If the methane concentration at all points within the scanning window remains below the preset threshold for 30 consecutive seconds, the PTZ scanning module automatically switches to the first scanning speed and resumes full-area cyclic scanning.

8. A gimbal scanning laser combustible gas detection device, employing a gimbal scanning laser combustible gas detection method as described in any one of claims 1 to 7, comprising an explosion-proof body (1), a gimbal scanning module, a laser detection module (2), and a camera monitoring module (3), wherein the explosion-proof body (1) is internally divided into multiple independent cavities, and the multiple independent cavities include a horizontal transmission cavity (4), a vertical transmission cavity (5), a visible light cavity (6), and a laser cavity (7); the gimbal scanning module includes a horizontal axis drive unit disposed in the horizontal transmission cavity (4) and a pitch axis drive unit disposed in the vertical transmission cavity (5); the laser detection module (2) and the camera monitoring module (3) are respectively disposed in the laser cavity (7) and the visible light cavity (6), characterized in that, Also includes: A rolling shaft drive unit is disposed inside the explosion-proof body (1). The rolling shaft drive unit is connected to the laser detection module (2) and the camera monitoring module (3) and drives the laser detection module (2) and the camera monitoring module (3) to swing left and right around the horizontal longitudinal direction.

9. A pan-tilt-zoom laser combustible gas detection device according to claim 8, characterized in that: The rolling shaft drive unit includes a spherical body (8) and a spherical cavity (9) located in the rolling transmission cavity (4) and connected to the horizontal transmission cavity (4) and the vertical transmission cavity (5) respectively. The spherical cavity (9) is adapted to roll with the spherical body (8). A rotating shaft (10) is horizontally inserted through the spherical cavity (9) along its longitudinal direction. The rotating shaft (10) extends horizontally into the spherical body (8). A worm gear (11) is provided on the rotating shaft (10) and part of the spherical body (8). A worm (12) driven by a motor is adapted to be provided on the worm gear (11).

10. A pan-tilt-zoom laser combustible gas detection device according to claim 9, characterized in that: A wire-passing hole (13) is provided on the vertical transmission cavity (5) corresponding to the center of the horizontal transmission cavity (4). A limiting block (14) for wire passing is provided in the wire-passing hole (13). An arc groove (15) is provided on the spherical body (8). The limiting block (14) moves relative to the arc groove (15) and follows the relative movement of the horizontal transmission cavity (4) and the vertical transmission cavity (5) without interfering with the arrangement of the cable.

Images