A visibility inversion method, device and equipment of a laser radar and a storage medium

Abstract

This application discloses a method, apparatus, device, and storage medium for lidar visibility inversion, relating to the field of laser technology. The method includes: determining the detection range boundary based on lidar voltage values ​​and a preset threshold; synchronously measuring visibility segmentally using a ground-based single-point visibility meter and a lidar visibility meter, and inverting the function value; constructing a joint relationship model based on the average error between the function value and the radar measurement signal, combined with the lidar equation, and generating a parameter mapping relationship lookup table; acquiring signal strength using a near-field visibility measurement device, and determining the target lidar ratio and extinction coefficient through the lookup table; finally, employing the Fernald inversion algorithm, combining the laser echo signal path, target extinction coefficient, and lidar ratio, to calculate the extinction coefficient profile and invert the visibility profile. This improves the efficiency of lidar visibility inversion.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a method, apparatus, device, and storage medium for retrieving visibility from a lidar system. Background Technology

[0002] Currently, traditional visibility meters (such as transilluminators and scatterometers) can only provide measurement data for a single point on the ground, making it difficult to reflect the spatial distribution characteristics of visibility over a large area. To obtain continuous, three-dimensional visibility information in both horizontal and vertical directions, visibility lidar is widely used in meteorology, transportation, and marine monitoring. This technology emits laser pulses to detect the backscattering signals of aerosols, fog droplets, and dust particles in the atmosphere, and then calculates the extinction coefficient using optical inversion algorithms, thereby deducing the three-dimensional spatial distribution of visibility. Compared to traditional equipment, lidar has the following advantages: it can achieve continuous monitoring of horizontal and vertical paths within a range of tens of kilometers, making it particularly suitable for scenarios requiring large-scale coverage, such as highways, airport runways, and ports; it can quickly respond to instantaneous changes in visibility, providing timely warnings for sudden low-visibility weather such as fog and sea fog; and it obtains high-resolution spatial visibility distribution maps through scanning modes, effectively compensating for the limitations of single-point measurements.

[0003] Currently, mainstream second visibility meters are mainly based on the Mie scattering principle, combined with high-sensitivity photoelectric detection and high-speed data acquisition technology, to measure the backscattered light intensity of particulate matter, and then use the slope method or Fernald and Klett methods to invert the extinction coefficient (σ) and calculate the visibility (V).

[0004] The slope method is based on the principle that, under uniform atmospheric conditions, the logarithm of the laser echo signal decreases linearly with distance, and its slope is directly related to the extinction coefficient. However, the slope method is only applicable to stable atmospheres where the signal is stable. If the aerosol distribution is uneven, signal fluctuations can lead to unreasonable results such as negative values ​​in the inversion.

[0005] The Fernald / Klett inversion method iteratively solves the lidar equations by setting boundary conditions (e.g., assuming a clean upper atmosphere) and a given lidar ratio (S). For vertical detection, the aerosol content above a certain altitude (e.g., 5 km) is typically assumed to approach zero, which serves as the boundary value for the extinction coefficient (usually set to zero). Simultaneously, an aerosol lidar ratio needs to be preset, usually a fixed value selected within the range of 20–50 sr. Based on these assumptions, the extinction coefficient profile along the laser path can be stably inverted.

[0006] However, in horizontal path detection, the path is usually located within the atmospheric boundary layer, where aerosol distribution is complex and variable, and it is difficult to determine suitable boundary values, which leads to a significant increase in inversion error. Furthermore, the optical properties of atmospheric composition differ significantly under different weather conditions (such as precipitation, haze, and clear skies), causing the actual lidar ratio (S) to be non-constant. Therefore, pre-setting a fixed lidar ratio in the inversion will also introduce additional errors.

[0007] As can be seen from the above, improving the efficiency of lidar visibility inversion is an urgent problem to be solved. Summary of the Invention

[0008] In view of this, the purpose of this invention is to provide a method, apparatus, device, and storage medium for lidar visibility inversion, which can improve the efficiency of lidar visibility inversion during the lidar visibility inversion process. The specific solution is as follows:

[0009] In a first aspect, this application provides a method for retrieving visibility from a lidar system, comprising:

[0010] Determine the lidar voltage value corresponding to the lidar echo signal, and determine each distance library and the farthest measurable distance library in each distance library based on the lidar voltage value and a preset voltage threshold, and set the farthest measurable distance library as the detection range boundary;

[0011] The visibility range within the detection range boundary is simultaneously measured segment by segment using a first visibility meter and a second visibility meter to obtain corresponding measurement data. The measurement data is then inverted to obtain the corresponding function value. The first visibility meter is used for single-point ground measurement. The second visibility meter is a lidar-based visibility meter used for continuous measurement.

[0012] The average error between each of the function values ​​and the lidar measurement signal output by the second visibility meter is determined. Then, the lidar equation is used and the lidar ratio and extinction coefficient to be processed corresponding to the average error are used to construct a target joint relationship model. Then, the target joint relationship model is used to generate a parameter mapping relationship lookup table.

[0013] The signal strength corresponding to the target distance is obtained using a visibility measurement device set at the near-field target distance of the lidar, and the target lidar ratio and target extinction coefficient are determined based on the parameter mapping relationship lookup table and the signal strength; the target distance is the distance corresponding to the distance in each of the distance databases that is closest to the near-field of the lidar.

[0014] The Fernald inversion algorithm is used to determine each extinction coefficient to be processed based on the laser path corresponding to the lidar echo signal, the target extinction coefficient and the ratio of the target lidar, so as to determine the visibility profile corresponding to the laser path based on each of the extinction coefficients to be processed.

[0015] Optionally, before determining the lidar voltage value corresponding to the lidar echo signal, the method further includes:

[0016] A lidar system is used to transmit lidar echo signals to an atmospheric detection area, and a coaxial telescope is used to receive the backscattered signals generated after the lidar echo signals are scattered by aerosols and cloud particles in the atmosphere.

[0017] The backscattered signal is processed by photoelectric conversion using a preset photoelectric conversion component to obtain a backscattered electrical signal. The backscattered electrical signal is then converted using a high-speed acquisition card to obtain a lidar echo signal to be compressed, corresponding to the lidar.

[0018] The detection blind zone of the lidar echo signal to be compressed is compressed using the coaxial transceiver integrated design in the coaxial telescope to obtain the compressed lidar echo signal. An initial geometric overlap factor corresponding to the compressed lidar echo signal is determined, and the initial geometric overlap factor is optimized to obtain the target geometric overlap factor. Then, the corresponding lidar echo signal is determined based on the compressed lidar echo signal and the target geometric overlap factor. The initial detection distance of the lidar echo signal meets the preset near-field range condition.

[0019] Optionally, determining the lidar voltage value corresponding to the lidar echo signal, and determining each distance library and the farthest measurable distance library in each distance library based on the lidar voltage value and a preset voltage threshold, and setting the farthest measurable distance library as the detection range boundary, includes:

[0020] Determine a number of single-pulse voltage values ​​corresponding to the lidar echo signal, and determine the voltage resolution, preset pulse accumulation count and preset voltage gain corresponding to the lidar echo signal. Then, determine the lidar voltage value based on each single-pulse voltage value, the preset pulse accumulation count and the preset voltage gain.

[0021] Based on the voltage resolution, the number of pulse accumulations, and the voltage gain, a preset voltage threshold for judging the validity of the data is determined, and it is determined whether the voltage value of the lidar is greater than the preset voltage threshold. If the voltage value of the lidar is greater than the preset voltage threshold, the data corresponding to the lidar echo signal is judged as valid data.

[0022] Determine the distance library corresponding to each of the valid data, and determine the farthest measurable distance library in each distance library. Then set the farthest measurable distance library as the detection range boundary; the farthest measurable distance library is not located in the blind zone or transition zone of the lidar echo signal.

[0023] Optionally, the step of simultaneously measuring the visibility range segments within the detection range boundary using a first visibility meter and a second visibility meter to obtain corresponding measurement data, and then inverting each measurement data to obtain the corresponding function value, includes:

[0024] The detection range boundary is divided into several continuous visibility range segments using a preset segment interval. A first visibility meter records the real-time visibility measurement data corresponding to the farthest distance in each visibility range segment. At the same time, a second visibility meter measures the corresponding observation signal intensity in each visibility range segment.

[0025] In each of the visibility range segments, a function expression for predicting signal intensity based on visibility values ​​is constructed. The real-time visibility measurement data and the observed signal intensity are then processed using the function expression to obtain the corresponding function value.

[0026] Optionally, the step of determining the average error between each of the function values ​​and the lidar measurement signal output by the second visibility meter, then constructing a target joint relationship model using the lidar equation and based on the unprocessed lidar ratio and unprocessed extinction coefficient corresponding to the average error, and then generating a parameter mapping relationship lookup table using the target joint relationship model, includes:

[0027] The current average error between each function value and each current observed signal intensity is determined, and it is determined whether the current average error is greater than a preset convergence flag value. If it is greater, the observed signal intensity corresponding to the largest error among the current average errors is removed, and the result after removal is set as the new current observed signal intensity. Then, the process jumps back to the step of determining the current average error between each function value and each current observed signal intensity until the current average error is less than the preset convergence flag value, and the processing result is obtained.

[0028] The operating wavelength of the lidar corresponding to the processing result is determined, and the reference wavelength corresponding to the first visibility meter is determined. The extinction coefficient to be processed is determined based on the conversion relationship between the operating wavelength of the lidar and the reference wavelength. Then, the lidar ratio to be processed is determined based on the current atmospheric conditions and the extinction coefficient to be processed.

[0029] A preset signal strength threshold range corresponding to the LiDAR echo signal is set, and a target joint relationship model including visibility, observed signal strength, LiDAR ratio, and wavelength conversion coefficient is constructed based on the preset signal strength threshold range, each LiDAR ratio to be processed, and the extinction coefficient to be processed. A parameter mapping relationship lookup table is generated based on the target joint relationship model. The parameter mapping relationship lookup table includes several visibility segments. The visibility segments are used to store the parameter combinations including LiDAR ratio and extinction coefficient corresponding to each visibility range segment.

[0030] Optionally, the step of acquiring the signal intensity corresponding to the target distance using a visibility measurement device located at the near-field target distance of the lidar, and determining the target lidar ratio and target extinction coefficient based on the parameter mapping lookup table and the signal intensity, includes:

[0031] A visibility measuring device is placed at the near-field target distance of the lidar to determine the real-time observed signal strength at the target distance. Based on the real-time observed signal strength, the parameter mapping table is consulted to obtain the corresponding real-time visibility, real-time lidar ratio, and real-time wavelength conversion coefficient. The real-time lidar ratio is used to characterize the current atmospheric scattering characteristics, and the real-time wavelength conversion coefficient is used to adjust for wavelength differences.

[0032] Determine the conversion relationship between the real-time visibility and the real-time wavelength conversion coefficient, and determine the target extinction coefficient at the target distance based on the conversion relationship.

[0033] Optionally, the step of using the Fernald inversion algorithm and determining each extinction coefficient to be processed based on the laser path corresponding to the lidar echo signal, the target extinction coefficient, and the ratio of the target extinction coefficient to the target lidar signal, and then determining the visibility profile corresponding to the laser path based on each of the extinction coefficients to be processed, includes:

[0034] The target extinction coefficient is set as a boundary condition, and the first lidar ratio to be processed corresponding to the air molecules in the lidar echo signal is determined using a preset theoretical constant value. Then, the first extinction coefficient to be processed corresponding to the air molecules is determined using a preset standard atmospheric model, so as to determine the first scattering characteristics based on the first lidar ratio to be processed and the first extinction coefficient to be processed.

[0035] Determine the second scattering characteristics, including the second lidar ratio to be processed and the second extinction coefficient to be processed, corresponding to the aerosol particles in the lidar echo signal;

[0036] In the laser path, the atmospheric scattering inversion equation is used, and path integration is performed based on the boundary conditions, the first scattering characteristic, the second scattering characteristic, the target extinction coefficient, and the ratio of the target extinction coefficient to the target lidar to obtain the extinction coefficient sequence corresponding to each of the range libraries in the laser path; the extinction coefficient sequence includes several extinction coefficients to be processed;

[0037] Based on the real-time wavelength conversion coefficient, the extinction coefficient sequence is inverted to obtain the visibility value corresponding to each distance point on the laser path, and a visibility profile on the horizontal path is generated based on each visibility value; the visibility profile is used to characterize the three-dimensional spatial distribution of atmospheric visibility.

[0038] Secondly, this application provides a visibility inversion device for lidar, comprising:

[0039] The lidar voltage value determination module is used to determine the lidar voltage value corresponding to the lidar echo signal, so as to determine each distance library and the farthest measurable distance library in each distance library based on the lidar voltage value and a preset voltage threshold, and set the farthest measurable distance library as the detection range boundary.

[0040] The measurement data determination module is used to simultaneously measure each visibility range segment within the boundary of the detection range using a first visibility meter and a second visibility meter, obtain corresponding measurement data, and perform inversion on each measurement data to obtain the corresponding function value; the first visibility meter is a visibility meter used for single-point ground measurement; the second visibility meter is a lidar-based visibility meter used for continuous measurement.

[0041] The relation lookup table determination module is used to determine the average error between each of the function values ​​and the lidar measurement signal output by the second visibility meter, and then construct a target joint relation model using the lidar equation and based on the lidar ratio to be processed and the extinction coefficient to be processed corresponding to the average error. Then, a parameter mapping relation lookup table is generated using the target joint relation model.

[0042] The signal strength determination module is used to acquire the signal strength corresponding to the target distance using a visibility measurement device set at the near-field target distance of the lidar, and to determine the target lidar ratio and target extinction coefficient based on the parameter mapping relationship lookup table and the signal strength; the target distance is the distance corresponding to the nearest distance to the near-field of the lidar in each of the distance databases;

[0043] The visibility profile generation module is used to determine each extinction coefficient to be processed based on the laser path corresponding to the lidar echo signal, the target extinction coefficient and the target lidar ratio using the fernald inversion algorithm, so as to determine the visibility profile corresponding to the laser path based on each of the extinction coefficients to be processed.

[0044] Thirdly, this application provides an electronic device, comprising:

[0045] Memory, used to store computer programs;

[0046] A processor is used to execute the computer program to implement the aforementioned lidar visibility inversion method.

[0047] Fourthly, this application provides a computer-readable storage medium for storing a computer program, wherein the computer program, when executed by a processor, implements the aforementioned lidar visibility inversion method.

[0048] As can be seen from the above, before performing the visibility inversion of the lidar, this application needs to determine the lidar voltage value corresponding to the lidar echo signal, so as to determine each range library and the farthest measurable range library in each range library based on the lidar voltage value and a preset voltage threshold, and set the farthest measurable range library as the detection range boundary; each range library is the detection distance corresponding to the lidar echo signal; the first visibility meter and the second visibility meter are used to simultaneously measure each segment of the visibility range within the detection range boundary to obtain the corresponding measurement data, and the measurement data are inverted to obtain the corresponding function value; the average error between each function value and the lidar measurement signal output by the second visibility meter is determined, and then the lidar equation is used and the distance is calculated. A joint target relationship model is constructed based on the unprocessed lidar ratio and unprocessed extinction coefficient corresponding to the average error. Then, a parameter mapping relationship lookup table is generated using the joint target relationship model. The signal intensity corresponding to the target distance is obtained using a visibility measurement device set at the near-field target distance of the lidar. The target lidar ratio and target extinction coefficient are determined based on the parameter mapping relationship lookup table and the signal intensity. The target distance is the distance corresponding to the distance closest to the near-field lidar in each distance database. The Fernald inversion algorithm is used to determine each unprocessed extinction coefficient based on the laser path corresponding to the lidar echo signal, the target extinction coefficient, and the target lidar ratio. The visibility profile corresponding to the laser path is then determined based on each unprocessed extinction coefficient.

[0049] Therefore, this application first needs to determine the lidar voltage value corresponding to the lidar echo signal, so as to determine each range library and the farthest measurable range library in each range library based on the lidar voltage value and a preset voltage threshold, and set the farthest measurable range library as the detection range boundary; secondly, the first visibility meter and the second visibility meter are used to simultaneously measure each segment of the visibility range within the detection range boundary to obtain the corresponding measurement data, and the measurement data are inverted to obtain the corresponding function value; the average error between each function value and the lidar measurement signal output by the second visibility meter is determined, and then the lidar equation is used and based on the average error... A joint target relationship model is constructed using the target lidar ratio and extinction coefficient to be processed, corresponding to the difference between the two. Then, a parameter mapping lookup table is generated using this model. Next, a visibility measurement device positioned at the near-field target distance of the lidar is used to acquire the signal intensity corresponding to the target distance. Based on the parameter mapping lookup table and the signal intensity, the target lidar ratio and target extinction coefficient are determined. Finally, the Fernald inversion algorithm is used, and based on the laser path corresponding to the lidar echo signal, the target extinction coefficient, and the target lidar ratio, each extinction coefficient to be processed is determined. Based on each extinction coefficient to be processed, the visibility profile corresponding to the laser path is determined. This improves the efficiency of lidar visibility inversion, thereby enhancing the user experience. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0051] Figure 1 This is a flowchart of a lidar visibility inversion method disclosed in this application;

[0052] Figure 2 This is a flowchart of a specific lidar visibility inversion method disclosed in this application;

[0053] Figure 3 This is a schematic diagram illustrating the verification results of visibility inversion for a lidar system disclosed in this application.

[0054] Figure 4 This is a schematic diagram of the visibility inversion device for a lidar disclosed in this application;

[0055] Figure 5 This is a structural diagram of an electronic device disclosed in this application. Detailed Implementation

[0056] 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 some embodiments of the present invention, and not all embodiments. 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.

[0057] Currently, traditional first-level visibility meters can only provide measurement data for a single point on the ground, making it difficult to reflect the spatial distribution characteristics of visibility over a large area. To obtain continuous, three-dimensional visibility information in both horizontal and vertical directions, visibility lidar is widely used in meteorological, traffic, and marine monitoring fields. However, in horizontal path detection, the path is usually located within the atmospheric boundary layer, where aerosol distribution is complex and variable, and it is difficult to determine suitable boundary values, which leads to a significant increase in inversion errors. Furthermore, the optical properties of atmospheric composition vary significantly under different weather conditions, resulting in the actual lidar ratio not being constant. Therefore, pre-setting a fixed lidar ratio in the inversion process also introduces additional errors. To address this, this application provides a lidar visibility inversion method that can improve the efficiency of lidar visibility inversion during the process.

[0058] See Figure 1 As shown in the figure, an embodiment of the present invention discloses a method for inverting the visibility of a lidar, comprising:

[0059] Step S11: Determine the lidar voltage value corresponding to the lidar echo signal, and determine each distance library and the farthest measurable distance library in each distance library based on the lidar voltage value and a preset voltage threshold, and set the farthest measurable distance library as the detection range boundary.

[0060] In this embodiment, the process of performing lidar visibility inversion is as follows: Figure 2 As shown: First, when the visibility lidar emits a single-wavelength laser beam into the detection area, after scattering and absorption by atmospheric aerosols / cloud particles, the backscattered signal corresponding to the single-wavelength laser beam is received using a coaxial telescope and converted into an electrical signal by a photoelectric conversion module. Subsequently, the above electrical signal undergoes voltage-to-digital conversion via a high-speed acquisition card, ultimately obtaining the lidar's echo information. It is worth mentioning that the system adopts a coaxial transceiver integrated design, effectively compressing the detection blind zone and optimizing the geometric overlap factor, reducing the initial detection distance of the effective echo signal to the near-field range.

[0061] Specifically, before determining the lidar voltage value corresponding to the lidar echo signal, the process may include: transmitting lidar echo signals to the atmospheric detection area using the lidar system, and receiving backscattered signals generated after the lidar echo signals are scattered by aerosols and cloud particles in the atmosphere using a coaxial telescope; performing photoelectric conversion processing on the backscattered signals using a preset photoelectric conversion component to obtain backscattered electrical signals, and then converting the backscattered electrical signals using a high-speed acquisition card to obtain the lidar echo signal to be compressed corresponding to the lidar; compressing the detection blind zone of the lidar echo signal to be compressed using the coaxial transceiver integrated design in the coaxial telescope to obtain the compressed lidar echo signal, and determining the initial geometric overlap factor corresponding to the compressed lidar echo signal, optimizing the initial geometric overlap factor to obtain the target geometric overlap factor, and then determining the corresponding lidar echo signal based on the compressed lidar echo signal and the target geometric overlap factor; the initial detection distance of the lidar echo signal meets the preset near-field range condition.

[0062] Subsequently, this embodiment of the application needs to calculate the farthest measurable distance library after the echo signal dead zone and transition zone, which can be specifically determined using the lidar voltage value, wherein the single pulse voltage value is Voltage resolution is If the number of radar pulse accumulations is q, then the radar accumulated voltage value is... G is the voltage gain, and the echo signal P can be expressed as: The furthest measurable distance beyond the echo signal dead zone and transition zone can be determined using the lidar voltage value. As a threshold, when When the data is valid, the position corresponding to the farthest valid value is the farthest detection distance of the echo signal.

[0063] Specifically, determining the lidar voltage value corresponding to the lidar echo signal, and determining each range library and the farthest measurable range library within each range library based on the lidar voltage value and a preset voltage threshold, and setting the farthest measurable range library as the detection range boundary, may include: determining several single-pulse voltage values ​​corresponding to the lidar echo signal, and determining the voltage resolution, preset pulse accumulation count, and preset voltage gain corresponding to the lidar echo signal; determining the lidar voltage value based on each single-pulse voltage value, the preset pulse accumulation count, and the preset voltage gain; determining a preset voltage threshold for judging data validity based on the voltage resolution, pulse accumulation count, and voltage gain, and judging whether the lidar voltage value is greater than the preset voltage threshold. If the lidar voltage value is greater than the preset voltage threshold, the data corresponding to the lidar echo signal is judged as valid data; determining the range library corresponding to each valid data, and determining the farthest measurable range library within each range library, and then setting the farthest measurable range library as the detection range boundary; the farthest measurable range library is not located in the blind zone or transition zone of the lidar echo signal.

[0064] In one specific implementation, the preset pulse accumulation count is 60,000 times, and the single pulse repetition frequency is 5 kHz. Setting it to 60,000 times is beneficial for accumulating signal strength and reducing signal noise. The preset voltage gain is determined by the detector model; in this embodiment, the detector gain is... V / W. The preset voltage threshold is 0.002mV. The threshold is determined by actual testing using the branch office acquisition board, which has a resolution of 0.00203mV. If the voltage is lower than the acquisition board resolution of 0.002mV, the signal is considered to have large fluctuations and is considered an invalid signal that cannot be identified.

[0065] Step S12: Simultaneously measure each visibility range segment within the detection range boundary using a first visibility meter and a second visibility meter to obtain corresponding measurement data, and invert each measurement data to obtain the corresponding function value; the first visibility meter is a visibility meter used for single-point ground measurement; the second visibility meter is a visibility meter based on lidar used for continuous measurement.

[0066] In this embodiment, according to the lidar equation, during the process of the lidar signal being emitted to the telescope receiving the signal, the distance... The signal at that location undergoes two-way extinction attenuation. This embodiment of the application can be verified by measuring the extinction coefficient. To calculate Backscattering coefficient at It is worth mentioning that this application embodiment uses a visibility meter as the calibration device. Since the visibility meter measures single-point visibility rather than path visibility, in order to reduce the uncertainty of the integral of the extinction coefficient on the path, this application embodiment uses a first distance without blind zones in the near field of the visibility lidar path and without the influence of the ensemble overlap factor. A visibility meter is installed at the location to measure the first distance. visibility Using Koschmieder's law, the first near-field distance can be calculated by inversion. extinction coefficient Wavelength conversion, Ångström exponent, etc., can be uniformly represented by the wavelength conversion coefficient. Instead, therefore, the first distance extinction coefficient It can be represented as:

[0067] ;

[0068] Subsequently, this embodiment of the application needs to calculate the first distance. The lidar at the location is more And it can be represented as:

[0069] ;

[0070] And, with corresponding backscattering coefficient It can be represented as:

[0071] ;

[0072] Furthermore, the visibility can be rewritten in the embodiments of this application. and measurement signals Nonlinear relationship:

[0073] ;

[0074] In one specific implementation, the visibility range is set to [0, L] meters, where L is the maximum measurable visibility range, which can be configured to 30,000 meters. Furthermore, the values ​​of S and K differ under different visibility conditions. Then, the visibility is divided into M segments, each segment covering a visibility range of [0, L]. Meter, represented as:

[0075] ;

[0076] Subsequently, a visibility meter and a visibility lidar were simultaneously activated for measurement, and the data measured by the visibility meter were recorded. The ratio of LiDAR corresponding to each segment is: With wavelength conversion coefficient In this way, the different visibility segments of each data point constitute the function model. It can be represented as:

[0077] ;

[0078] Specifically, the first and second visibility meters are used to simultaneously measure the visibility range segments within the detection range boundary, obtaining corresponding measurement data. These measurement data are then inverted to obtain corresponding function values. This process can include: dividing the detection range boundary into several continuous visibility range segments using a preset segmentation interval; recording real-time visibility measurement data corresponding to the farthest distance in each visibility range segment using the first visibility meter; simultaneously measuring the corresponding observed signal intensity in each visibility range segment using the second visibility meter; constructing function expressions for predicting signal intensity based on visibility values ​​in each visibility range segment; and processing the real-time visibility measurement data and observed signal intensity using these function expressions to obtain the corresponding function values.

[0079] Step S13: Determine the average error between each of the function values ​​and the lidar measurement signal output by the second visibility meter. Then, construct a target joint relationship model using the lidar equation and based on the lidar ratio and extinction coefficient to be processed corresponding to the average error. Finally, generate a parameter mapping relationship lookup table using the target joint relationship model.

[0080] In this embodiment, during model calculation, it is necessary to control data exceeding the model limits. For example, saturation data during dense fog and data approaching noise levels have a significant impact on the confirmation of model parameters. In one specific implementation, a signal threshold range is set. The maximum and minimum values ​​for data to participate in the model calculation are limited; signals outside these ranges are excluded from the calculation. The amount of data used in model building is... Number Calculation function and lidar measurement signals The method for calculating the average error between data is as follows:

[0081] ;

[0082] Subsequently, in one specific implementation, the model convergence flag value is set to... If the error Greater than the error flag value This indicates that the data currently being calculated may contain outliers, leading to significant errors, and requires iteration. Each data point has its own individual error. The method for calculating the error of a single data item is as follows:

[0083] ;

[0084] Subsequently, the largest single-item error was corresponding to After elimination, the embodiments of this application need to be based on the remaining The error is calculated by repeatedly executing the data using a model formula. This step is repeated iteratively until the error is reached. Below the set convergence flag value Output global error The minimum corresponding and Value, as The visibility segment model optimizes parameters, and based on this, a joint relationship model of visibility, lidar echo signal, lidar ratio, and wavelength conversion coefficient is constructed to generate visibility. and signal LiDAR Wavelength conversion coefficient A lookup table for multi-parameter mapping relationships.

[0085] In one specific implementation, the mapping relationship between signal strength, visibility, and lidar ratio is shown in Table 1:

[0086] Table 1. Mapping Relationship between Signal Strength, Visibility, and LiDAR Ratio

[0087]

[0088] Specifically, the average error between each function value and the lidar measurement signal output by the second visibility meter is determined. Then, a joint target relationship model is constructed using the lidar equation and based on the lidar ratio and extinction coefficient to be processed corresponding to the average error. A parameter mapping lookup table is then generated using this model. This process may include: determining the current average error between each function value and each currently observed signal intensity, and determining whether the current average error is greater than a preset convergence flag. If it is greater, the observed signal intensity corresponding to the largest error among the current average errors is removed, and the removed result is set as the new current observed signal intensities. Then, the process returns to the step of determining the current average error between each function value and each currently observed signal intensity until the current average error is less than the preset convergence flag, thus obtaining the processing result. The operating wavelength of the lidar corresponding to the processing result is determined, and the reference wavelength corresponding to the first visibility meter is also determined. The extinction coefficient to be processed is determined based on the conversion relationship between the lidar operating wavelength and the reference wavelength. Then, the lidar ratio to be processed is determined based on the current atmospheric conditions and the extinction coefficient to be processed. A preset signal intensity threshold range corresponding to the signal intensity of the lidar echo signal is set. Based on the preset signal intensity threshold range, each lidar ratio to be processed, and the extinction coefficient to be processed, a target joint relationship model including visibility, observed signal intensity, lidar ratio, and wavelength conversion coefficient is constructed. A parameter mapping relationship lookup table is generated based on the target joint relationship model. The parameter mapping relationship lookup table includes several visibility segments. The visibility segments are used to store the parameter combinations including lidar ratio and extinction coefficient corresponding to each visibility range segment.

[0089] In one specific implementation, the preset convergence flag value can be determined by the residual between the fitted value and the measured value, and the corresponding actual test threshold is 0.5. Further, the maximum value in the preset signal strength threshold range is the maximum value among the voltage saturation values ​​in each dense fog weather condition, and the minimum value in the preset signal strength threshold range is the minimum signal strength corresponding to the weakest signal data with only noise remaining. If the value exceeds the range, it is considered to be outside the radar measurement range and cannot participate in the fitting calculation, and the preset signal strength threshold range can be [0.002mV-640mV].

[0090] Step S14: Use the visibility measurement device set at the near-field target distance of the lidar to obtain the signal intensity corresponding to the target distance, and determine the target lidar ratio and target extinction coefficient based on the parameter mapping relationship lookup table and the signal intensity; the target distance is the distance corresponding to the distance library closest to the near-field of the lidar in each of the distance libraries.

[0091] In this embodiment, the distances corresponding to each distance database are... ,in, This represents the first effective distance library unaffected by blind zones and transition effects of geometric overlap factors. This represents the furthest distance database after removing blind spots and transition zones, with each distance... The observed signal strength is denoted as The atmospheric backscattering coefficient at the corresponding location is The extinction coefficient is The inherent parameters of lidar, such as emission energy, system efficiency, and telescope receiving area, are uniformly summarized into system constants. , =1, where the lidar equation is expressed as:

[0092] ;

[0093] Furthermore, Backscattering coefficient at a distance It can be represented as:

[0094] .

[0095] Specifically, the method involves using a visibility measurement device positioned at the near-field target distance of the lidar to acquire the signal intensity corresponding to the target distance, and determining the target lidar ratio and target extinction coefficient based on a parameter mapping lookup table and the signal intensity. This can include: placing a visibility measurement device at the near-field target distance of the lidar to determine the real-time observed signal intensity at the target distance, and using the real-time observed signal intensity to look up the parameter mapping lookup table to obtain the corresponding real-time visibility, real-time lidar ratio, and real-time wavelength conversion coefficient; the real-time lidar ratio is used to characterize the current atmospheric scattering characteristics; the real-time wavelength conversion coefficient is used to adjust for wavelength differences; and determining the conversion relationship between real-time visibility and real-time wavelength conversion coefficient to determine the target extinction coefficient at the target distance based on the conversion relationship.

[0096] Step S15: Use the visibility measurement device set at the near-field target distance of the lidar to obtain the signal strength corresponding to the target distance, and determine the target lidar ratio and target extinction coefficient based on the parameter mapping relationship lookup table and the signal strength; the target distance is the distance corresponding to the distance in the distance library that is closest to the near-field lidar in each distance library.

[0097] In this embodiment, after calibration, the visibility lidar can perform independent observations, wherein the measured signal is... The table is looked up using a multi-parameter mapping relationship, and the first distance is used to determine the relationship. Measured signal Initial visibility can be obtained. LiDAR Wavelength conversion coefficient Among them, the first distance Extinction coefficient It can be represented as:

[0098] ;

[0099] Subsequently, the optimized As the initial extinction coefficient, and Simultaneously, substituting into Fernard's formula, the extinction coefficient along the laser path can be calculated by back integration, expressed as:

[0100] ;

[0101] in, Represents air molecules, , It can be calculated from the vertical profile of air molecule density provided by the standard atmospheric model based on the atmospheric Rayleigh scattering theory.

[0102] Finally, calculate the final visibility. A profile can be represented as:

[0103] .

[0104] Specifically, the Fernald inversion algorithm is used to determine each extinction coefficient to be processed based on the laser path corresponding to the lidar echo signal, the target extinction coefficient, and the target lidar ratio. The visibility profile corresponding to the laser path is then determined based on each extinction coefficient to be processed. This can include: setting the target extinction coefficient as a boundary condition, determining the first lidar ratio to be processed corresponding to air molecules in the lidar echo signal using a preset theoretical constant value, then determining the first extinction coefficient to be processed corresponding to air molecules using a preset standard atmospheric model, and determining the first scattering characteristic based on the first lidar ratio to be processed and the first extinction coefficient to be processed; determining the relationship between the lidar echo signal and the target lidar ratio. The aerosol particles in the model correspond to the second scattering characteristic, which includes the second unprocessed lidar ratio and the second unprocessed extinction coefficient. In the laser path, the atmospheric scattering inversion equation is used, and path integration is performed based on boundary conditions, the first scattering characteristic, the second scattering characteristic, the target extinction coefficient, and the target lidar ratio to obtain the extinction coefficient sequence corresponding to each distance in the laser path. The extinction coefficient sequence includes several unprocessed extinction coefficients. Based on the real-time wavelength conversion coefficient, the extinction coefficient sequence is inverted to obtain the visibility value corresponding to each distance point on the laser path. A visibility profile on the horizontal path is generated based on these visibility values. The visibility profile is used to characterize the three-dimensional spatial distribution of atmospheric visibility. In one specific implementation, the preset theoretical constant value is 1. Subsequent steps mainly rely on a fitting function model to invert various parameters; therefore, setting the constant to 1 is for normalization and does not affect the fitting model calculation.

[0105] Furthermore, embodiments of this application can be based on the Rayleigh scattering mechanism and apply the atmospheric molecular scattering cross section and atmospheric molecular density to calculate the backscattering coefficient of atmospheric molecules, i.e., the first scattering characteristic:

[0106] ;

[0107] Among them, the atmospheric molecular backscattering coefficient ( The backscattering cross section of atmospheric molecules per unit volume and unit solid angle is defined as the cross section of atmospheric molecules backscattering per unit volume and unit solid angle. The single-molecule backscattering cross section ( ), The number of atmospheric molecules per unit volume, i.e., molecular number density. ).

[0108] The backscattering cross section of a single molecule is mainly related to the excitation wavelength. The formula for calculating the backscattering cross section of an atmospheric single molecule below 100 km can be expressed as:

[0109] ;

[0110] in, The wavelength is the laser wavelength, measured in nm.

[0111] Similarly, molecular number density can be calculated using atmospheric pressure and atmospheric temperature, and the specific calculation formula is as follows:

[0112] ;

[0113] in, for Atmospheric temperature at altitude, in Kelvin As a unit; For the atmosphere in Pressure at height, expressed in Pascal's law As a unit; Atmospheric temperature is 296 K and pressure is The reference value for atmospheric molecular density at Pa is [value missing]. .

[0114] In this embodiment, the preset standard atmospheric model can be the standard atmospheric model of 1976. This embodiment can be based on the temperature and pressure data of the above-mentioned standard atmospheric model and converted into altitude using the molecular number density calculation formula. A function (in units of m), namely:

[0115] ;

[0116] in, , .

[0117] It is worth mentioning that the first extinction coefficient to be treated for air molecules can be expressed as:

[0118] ;

[0119] Furthermore, the second scattering characteristic The echo signal can be detected and expressed as an intermediate quantity, serving to establish the relationship between the aerosol extinction coefficient and the echo signal. In this embodiment, the minimum error satisfying the threshold can be calculated by fitting a model to obtain the values ​​under different visibility ranges. and Value, as The visibility segment model optimizes parameters, and based on this, a joint relationship model of visibility, lidar echo signal, lidar ratio, and wavelength conversion coefficient is constructed to generate visibility. and signal LiDAR Wavelength conversion coefficient A multi-parameter mapping relationship lookup table. After calibration, the visibility lidar can perform independent observations, obtaining different visibility values ​​through the lookup table. Boundary values ​​below :

[0120] Will As the initial extinction coefficient, and Simultaneously, substituting into Fernard's formula, the extinction coefficient along the laser path can be calculated by backward integration:

[0121] ;

[0122] The second scattering characteristic of the intermediate process quantity Through formula = / Calculations are performed to obtain the results.

[0123] In this embodiment, the first visibility meter (single ground point) and the second visibility meter (LiDAR) are used for synchronous measurement, dividing the detection range into multiple visibility intervals. Then, a lookup table of the mapping relationship between signal strength, visibility, and LiDAR ratio is established through piecewise fitting, and parameter combinations are pre-calculated in one go. Subsequent inversion directly looks up the table instead of real-time iterative solution. A measuring device is placed in the near field of the LiDAR to obtain the near field signal strength in real time as the boundary condition, replacing the traditional empirical assumptions (such as clean air above 5 km), reducing the error caused by the fixed LiDAR ratio (20–50 sr). The lookup table is used to quickly match the target LiDAR ratio and extinction coefficient, eliminating the repeated parameter estimation steps in the inversion process, and realizing the generation of the visibility profile by one integration. Subsequently, through offline table building and online table lookup, the complex nonlinear boundary ambiguity inversion is transformed into table lookup and single integration operation. The near field measured boundary conditions also ensure accuracy, such as... Figure 3 As shown. Furthermore, traditional calculation methods mainly rely on complex formulas for inversion; by establishing a lookup table, complex calculations are unnecessary, thus improving inversion speed.

[0124] As can be seen from the above, the embodiments of this application first need to determine the lidar voltage value corresponding to the lidar echo signal, so as to determine each distance library and the farthest measurable distance library in each distance library based on the lidar voltage value and a preset voltage threshold, and set the farthest measurable distance library as the detection range boundary; secondly, the first visibility meter and the second visibility meter are used to simultaneously measure each segment of the visibility range in the detection range boundary to obtain the corresponding measurement data, and the measurement data are inverted to obtain the corresponding function value; the average error between each function value and the lidar measurement signal output by the second visibility meter is determined, and then the lidar equation is used and based on the average error is calculated. A joint target relationship model is constructed using the unprocessed lidar ratio and unprocessed extinction coefficient corresponding to the error. Then, a parameter mapping lookup table is generated using this model. Next, a visibility measurement device positioned at the near-field target distance of the lidar is used to acquire the signal intensity corresponding to the target distance. Based on the parameter mapping lookup table and the signal intensity, the target lidar ratio and target extinction coefficient are determined. Finally, the Fernald inversion algorithm is used, and based on the laser path corresponding to the lidar echo signal, the target extinction coefficient, and the target lidar ratio, each unprocessed extinction coefficient is determined. Based on each unprocessed extinction coefficient, the visibility profile corresponding to the laser path is determined. This improves the efficiency of lidar visibility inversion, thereby enhancing the user experience.

[0125] Accordingly, see Figure 4 As shown, this application also provides a visibility inversion device for lidar, comprising:

[0126] The lidar voltage value determination module 11 is used to determine the lidar voltage value corresponding to the lidar echo signal, so as to determine each distance library and the farthest measurable distance library in each distance library based on the lidar voltage value and a preset voltage threshold, and set the farthest measurable distance library as the detection range boundary.

[0127] The measurement data determination module 12 is used to simultaneously measure each visibility range segment within the boundary of the detection range using a first visibility meter and a second visibility meter, obtain corresponding measurement data, and perform inversion on each measurement data to obtain the corresponding function value; the first visibility meter is a visibility meter used for single-point ground measurement; the second visibility meter is a lidar-based visibility meter used for continuous measurement.

[0128] The relation lookup table determination module 13 is used to determine the average error between each of the function values ​​and the lidar measurement signal output by the second visibility meter, and then construct a target joint relation model using the lidar equation and based on the lidar ratio to be processed and the extinction coefficient to be processed corresponding to the average error. Then, a parameter mapping relation lookup table is generated using the target joint relation model.

[0129] The signal strength determination module 14 is used to obtain the signal strength corresponding to the target distance using a visibility measurement device set at the near-field target distance of the lidar, and to determine the target lidar ratio and target extinction coefficient based on the parameter mapping relationship lookup table and the signal strength; the target distance is the distance corresponding to the distance closest to the near-field of the lidar in each of the distance databases;

[0130] The visibility profile generation module 15 is used to determine each extinction coefficient to be processed based on the laser path corresponding to the lidar echo signal, the target extinction coefficient and the target lidar ratio using the fernald inversion algorithm, so as to determine the visibility profile corresponding to the laser path based on each of the extinction coefficients to be processed.

[0131] In some specific embodiments, the visibility inversion device of the lidar may further include:

[0132] The signal transmitting unit is used to transmit lidar echo signals to the atmospheric detection area using the lidar system, and to receive the backscattered signals generated by the lidar echo signals after being scattered by aerosols and cloud particles in the atmosphere using a coaxial telescope.

[0133] The signal photoelectric conversion unit is used to perform photoelectric conversion processing on the backscattered signal using a preset photoelectric conversion component to obtain a backscattered electrical signal, and then use a high-speed acquisition card to convert the backscattered electrical signal to obtain a lidar echo signal to be compressed corresponding to the lidar.

[0134] The detection blind zone compression unit is used to compress the detection blind zone of the lidar echo signal to be compressed by utilizing the coaxial transceiver integrated design in the coaxial telescope, to obtain the compressed lidar echo signal, and to determine the initial geometric overlap factor corresponding to the compressed lidar echo signal, so as to optimize the initial geometric overlap factor to obtain the target geometric overlap factor. Then, based on the compressed lidar echo signal and the target geometric overlap factor, the corresponding lidar echo signal is determined; the initial detection distance of the lidar echo signal meets the preset near-field range condition.

[0135] In some specific embodiments, the lidar voltage value determination module 11 may specifically include:

[0136] The lidar voltage value determination subunit is used to determine a number of single-pulse voltage values ​​corresponding to the lidar echo signal, and to determine the voltage resolution, preset pulse accumulation count and preset voltage gain corresponding to the lidar echo signal, and to determine the lidar voltage value based on each single-pulse voltage value, the preset pulse accumulation count and the preset voltage gain;

[0137] The voltage threshold determination unit is used to determine a preset voltage threshold for judging the validity of data based on the voltage resolution, the number of pulse accumulations and the voltage gain, and to determine whether the lidar voltage value is greater than the preset voltage threshold. If the lidar voltage value is greater than the preset voltage threshold, the data corresponding to the lidar echo signal is judged as valid data.

[0138] The farthest measurable distance library determination unit is used to determine the distance library corresponding to each of the valid data, and to determine the farthest measurable distance library in each of the distance libraries, and then set the farthest measurable distance library as the detection range boundary; the farthest measurable distance library is not located in the blind zone and transition zone of the lidar echo signal.

[0139] In some specific embodiments, the measurement data determination module 12 may specifically include:

[0140] The observation signal strength determination unit is used to divide the detection range boundary into several continuous visibility range segments using a preset segment interval, and to use a first visibility meter to record the real-time visibility measurement data corresponding to the farthest distance library in each visibility range segment, and to use a second visibility meter to measure the corresponding observation signal strength in each visibility range segment.

[0141] The function value generation unit is used to construct function expressions for predicting signal intensity based on visibility values ​​in each visibility range segment, so as to process the real-time visibility measurement data and the observed signal intensity using the function expressions to obtain the corresponding function values.

[0142] In some specific embodiments, the relationship lookup table determination module 13 may specifically include:

[0143] The average error judgment unit is used to determine the current average error between each function value and each current observed signal intensity, and to determine whether the current average error is greater than a preset convergence flag value. If it is greater, the observed signal intensity corresponding to the largest error among the current average errors is removed, and the result after removal is set as the new current observed signal intensity. Then, the process jumps back to the step of determining the current average error between each function value and each current observed signal intensity until the current average error is less than the preset convergence flag value, and the processing result is obtained.

[0144] A reference wavelength determination unit is used to determine the working wavelength of the lidar corresponding to the processing result, and to determine the reference wavelength corresponding to the first visibility meter, so as to determine the extinction coefficient to be processed based on the conversion relationship between the working wavelength of the lidar and the reference wavelength, and then determine the lidar ratio to be processed based on the current atmospheric conditions and the extinction coefficient to be processed.

[0145] The mapping relationship lookup table generation unit is used to set a preset signal strength threshold range for the signal strength corresponding to the lidar echo signal, and to construct a target joint relationship model including visibility, observed signal strength, lidar ratio, and wavelength conversion coefficient based on the preset signal strength threshold range, each lidar ratio to be processed, and the extinction coefficient to be processed, so as to generate a parameter mapping relationship lookup table based on the target joint relationship model; the parameter mapping relationship lookup table includes several visibility segments; the visibility segments are used to store the parameter combinations including lidar ratio and extinction coefficient corresponding to each visibility range segment.

[0146] In some specific embodiments, the signal strength determination module 14 may specifically include:

[0147] The lookup table lookup unit is used to place a visibility measurement device at the near-field target distance of the lidar, to determine the real-time observed signal strength at the target distance using the visibility measurement device, and to look up the parameter mapping relationship lookup table based on the real-time observed signal strength to obtain the corresponding real-time visibility, real-time lidar ratio, and real-time wavelength conversion coefficient; the real-time lidar ratio is used to characterize the current atmospheric scattering characteristics; the real-time wavelength conversion coefficient is used to adjust wavelength differences;

[0148] A conversion relationship determination unit is used to determine the conversion relationship between the real-time visibility and the real-time wavelength conversion coefficient, so as to determine the target extinction coefficient at the target distance based on the conversion relationship.

[0149] In some specific embodiments, the visibility profile generation module 15 may specifically include:

[0150] The first scattering characteristic determination unit is used to set the target extinction coefficient as a boundary condition, and use a preset theoretical constant value to determine the first lidar ratio to be processed corresponding to the air molecules in the lidar echo signal. Then, it uses a preset standard atmospheric model to determine the first extinction coefficient to be processed corresponding to the air molecules, so as to determine the first scattering characteristic based on the first lidar ratio to be processed and the first extinction coefficient to be processed.

[0151] The second scattering characteristic determination unit is used to determine the second scattering characteristic corresponding to the aerosol particles in the lidar echo signal, including the second lidar ratio to be processed and the second extinction coefficient to be processed.

[0152] An extinction coefficient sequence generation unit is used to perform path integral calculations in the laser path using atmospheric scattering inversion equations and based on the boundary conditions, the first scattering characteristic, the second scattering characteristic, and the ratio of the target extinction coefficient to the target lidar, to obtain an extinction coefficient sequence corresponding to each of the distance libraries in the laser path; the extinction coefficient sequence includes several extinction coefficients to be processed;

[0153] A visibility profile generation unit is used to invert the extinction coefficient sequence based on the real-time wavelength conversion coefficient to obtain the visibility value corresponding to each distance point on the laser path, and to generate a visibility profile on the horizontal path based on each visibility value; the visibility profile is used to characterize the three-dimensional spatial distribution of atmospheric visibility.

[0154] Furthermore, embodiments of this application also disclose an electronic device, Figure 5 This is a structural diagram of an electronic device 20 according to an exemplary embodiment. The content of the diagram should not be construed as limiting the scope of this application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. The memory 22 stores a computer program, which is loaded and executed by the processor 21 to implement the relevant steps in the lidar visibility inversion method disclosed in any of the foregoing embodiments. Furthermore, the electronic device 20 in this embodiment may specifically be a computer.

[0155] In this embodiment, the power supply 23 is used to provide operating voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and external devices, and the communication protocol it follows can be any communication protocol applicable to the technical solution of this application, and is not specifically limited here; the input / output interface 25 is used to acquire external input data or output data to the outside world, and its specific interface type can be selected according to specific application needs, and is not specifically limited here.

[0156] In addition, the memory 22, as a carrier for resource storage, can be a read-only memory, random access memory, disk or optical disk, etc. The resources stored thereon can include operating system 221, computer program 222, etc., and the storage method can be temporary storage or permanent storage.

[0157] The operating system 221 is used to manage and control the various hardware devices on the electronic device 20 and the computer program 222, which may be Windows Server, Netware, Unix, Linux, etc. In addition to including a computer program capable of performing the lidar visibility inversion method executed by the electronic device 20 as disclosed in any of the foregoing embodiments, the computer program 222 may further include computer programs capable of performing other specific tasks.

[0158] Furthermore, this application also discloses a computer-readable storage medium for storing a computer program; wherein, when the computer program is executed by a processor, it implements the aforementioned lidar visibility inversion method. Specific steps of this method can be found in the corresponding content disclosed in the foregoing embodiments, and will not be repeated here.

[0159] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0160] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0161] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0162] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0163] The technical solutions provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for inverting visibility using a lidar system, characterized in that, include: Determine the lidar voltage value corresponding to the lidar echo signal, and determine each distance library and the farthest measurable distance library in each distance library based on the lidar voltage value and a preset voltage threshold, and set the farthest measurable distance library as the detection range boundary; The visibility range within the detection range boundary is simultaneously measured segment by segment using a first visibility meter and a second visibility meter to obtain corresponding measurement data. The measurement data is then inverted to obtain the corresponding function value. The first visibility meter is used for single-point ground measurement. The second visibility meter is a lidar-based visibility meter used for continuous measurement. The average error between each of the function values ​​and the lidar measurement signal output by the second visibility meter is determined. Then, the lidar equation is used and the lidar ratio and extinction coefficient to be processed corresponding to the average error are used to construct a target joint relationship model. Then, the target joint relationship model is used to generate a parameter mapping relationship lookup table. The signal strength corresponding to the target distance is obtained using a visibility measurement device set at the near-field target distance of the lidar, and the target lidar ratio and target extinction coefficient are determined based on the parameter mapping relationship lookup table and the signal strength; the target distance is the distance corresponding to the distance in each of the distance databases that is closest to the near-field of the lidar. The Fernald inversion algorithm is used to determine each extinction coefficient to be processed based on the laser path corresponding to the lidar echo signal, the target extinction coefficient and the ratio of the target lidar, so as to determine the visibility profile corresponding to the laser path based on each of the extinction coefficients to be processed.

2. The visibility inversion method for lidar according to claim 1, characterized in that, Before determining the lidar voltage value corresponding to the lidar echo signal, the process also includes: A lidar system is used to transmit lidar echo signals to an atmospheric detection area, and a coaxial telescope is used to receive the backscattered signals generated after the lidar echo signals are scattered by aerosols and cloud particles in the atmosphere. The backscattered signal is processed by photoelectric conversion using a preset photoelectric conversion component to obtain a backscattered electrical signal. The backscattered electrical signal is then converted using a high-speed acquisition card to obtain a lidar echo signal to be compressed, corresponding to the lidar. The detection blind zone of the lidar echo signal to be compressed is compressed using the coaxial transceiver integrated design in the coaxial telescope to obtain the compressed lidar echo signal. An initial geometric overlap factor corresponding to the compressed lidar echo signal is determined, and the initial geometric overlap factor is optimized to obtain the target geometric overlap factor. Then, the corresponding lidar echo signal is determined based on the compressed lidar echo signal and the target geometric overlap factor. The initial detection distance of the lidar echo signal meets the preset near-field range condition.

3. The visibility inversion method for lidar according to claim 1, characterized in that, The process of determining the lidar voltage value corresponding to the lidar echo signal, determining each distance library and the farthest measurable distance library in each distance library based on the lidar voltage value and a preset voltage threshold, and setting the farthest measurable distance library as the detection range boundary includes: Determine a number of single-pulse voltage values ​​corresponding to the lidar echo signal, and determine the voltage resolution, preset pulse accumulation count and preset voltage gain corresponding to the lidar echo signal. Then, determine the lidar voltage value based on each single-pulse voltage value, the preset pulse accumulation count and the preset voltage gain. Based on the voltage resolution, the number of pulse accumulations, and the voltage gain, a preset voltage threshold for judging the validity of the data is determined, and it is determined whether the voltage value of the lidar is greater than the preset voltage threshold. If the voltage value of the lidar is greater than the preset voltage threshold, the data corresponding to the lidar echo signal is judged as valid data. Determine the distance library corresponding to each of the valid data, and determine the farthest measurable distance library in each distance library. Then set the farthest measurable distance library as the detection range boundary; the farthest measurable distance library is not located in the blind zone or transition zone of the lidar echo signal.

4. The visibility inversion method for lidar according to claim 1, characterized in that, The method involves simultaneously measuring the visibility range segment by segment within the detection range boundary using a first visibility meter and a second visibility meter to obtain corresponding measurement data, and then inverting the measurement data to obtain corresponding function values, including: The detection range boundary is divided into several continuous visibility range segments using a preset segment interval. A first visibility meter records the real-time visibility measurement data corresponding to the farthest distance in each visibility range segment. At the same time, a second visibility meter measures the corresponding observation signal intensity in each visibility range segment. In each of the visibility range segments, a function expression for predicting signal intensity based on visibility values ​​is constructed. The real-time visibility measurement data and the observed signal intensity are then processed using the function expression to obtain the corresponding function value.

5. The visibility inversion method for lidar according to claim 4, characterized in that, The process involves determining the average error between each function value and the lidar measurement signal output by the second visibility meter, then constructing a target joint relationship model using the lidar equation and based on the unprocessed lidar ratio and unprocessed extinction coefficient corresponding to the average error, and finally generating a parameter mapping relationship lookup table using the target joint relationship model, including: The current average error between each function value and each current observed signal intensity is determined, and it is determined whether the current average error is greater than a preset convergence flag value. If it is greater, the observed signal intensity corresponding to the largest error among the current average errors is removed, and the result after removal is set as the new current observed signal intensity. Then, the process jumps back to the step of determining the current average error between each function value and each current observed signal intensity until the current average error is less than the preset convergence flag value, and the processing result is obtained. The operating wavelength of the lidar corresponding to the processing result is determined, and the reference wavelength corresponding to the first visibility meter is determined. The extinction coefficient to be processed is determined based on the conversion relationship between the operating wavelength of the lidar and the reference wavelength. Then, the lidar ratio to be processed is determined based on the current atmospheric conditions and the extinction coefficient to be processed. A preset signal strength threshold range corresponding to the LiDAR echo signal is set, and a target joint relationship model including visibility, observed signal strength, LiDAR ratio, and wavelength conversion coefficient is constructed based on the preset signal strength threshold range, each LiDAR ratio to be processed, and the extinction coefficient to be processed. A parameter mapping relationship lookup table is generated based on the target joint relationship model. The parameter mapping relationship lookup table includes several visibility segments. The visibility segments are used to store the parameter combinations including LiDAR ratio and extinction coefficient corresponding to each visibility range segment.

6. The visibility inversion method for lidar according to any one of claims 1 to 5, characterized in that, The step of acquiring the signal strength corresponding to the target distance using a visibility measurement device installed at the near-field target distance of the lidar, and determining the target lidar ratio and target extinction coefficient based on the parameter mapping lookup table and the signal strength, includes: A visibility measuring device is placed at the near-field target distance of the lidar to determine the real-time observed signal strength at the target distance. Based on the real-time observed signal strength, the parameter mapping table is consulted to obtain the corresponding real-time visibility, real-time lidar ratio, and real-time wavelength conversion coefficient. The real-time lidar ratio is used to characterize the current atmospheric scattering characteristics, and the real-time wavelength conversion coefficient is used to adjust for wavelength differences. Determine the conversion relationship between the real-time visibility and the real-time wavelength conversion coefficient, and determine the target extinction coefficient at the target distance based on the conversion relationship.

7. The visibility inversion method for lidar according to claim 6, characterized in that, The step of using the Fernald inversion algorithm and determining each extinction coefficient to be processed based on the laser path corresponding to the lidar echo signal, the target extinction coefficient, and the ratio of the target extinction coefficient to the target lidar signal, and then determining the visibility profile corresponding to the laser path based on each of the extinction coefficients to be processed, includes: The target extinction coefficient is set as a boundary condition, and the first lidar ratio to be processed corresponding to the air molecules in the lidar echo signal is determined using a preset theoretical constant value. Then, the first extinction coefficient to be processed corresponding to the air molecules is determined using a preset standard atmospheric model, so as to determine the first scattering characteristics based on the first lidar ratio to be processed and the first extinction coefficient to be processed. Determine the second scattering characteristics, including the second lidar ratio to be processed and the second extinction coefficient to be processed, corresponding to the aerosol particles in the lidar echo signal; In the laser path, the atmospheric scattering inversion equation is used, and path integration is performed based on the boundary conditions, the first scattering characteristic, the second scattering characteristic, the target extinction coefficient, and the ratio of the target extinction coefficient to the target lidar to obtain the extinction coefficient sequence corresponding to each of the range libraries in the laser path; the extinction coefficient sequence includes several extinction coefficients to be processed; Based on the real-time wavelength conversion coefficient, the extinction coefficient sequence is inverted to obtain the visibility value corresponding to each distance point on the laser path, and a visibility profile on the horizontal path is generated based on each visibility value; the visibility profile is used to characterize the three-dimensional spatial distribution of atmospheric visibility.

8. A visibility inversion device for lidar, characterized in that, include: The lidar voltage value determination module is used to determine the lidar voltage value corresponding to the lidar echo signal, so as to determine each distance library and the farthest measurable distance library in each distance library based on the lidar voltage value and a preset voltage threshold, and set the farthest measurable distance library as the detection range boundary. The measurement data determination module is used to simultaneously measure each visibility range segment within the boundary of the detection range using a first visibility meter and a second visibility meter, obtain corresponding measurement data, and perform inversion on each measurement data to obtain the corresponding function value; the first visibility meter is a visibility meter used for single-point ground measurement; the second visibility meter is a lidar-based visibility meter used for continuous measurement. The relation lookup table determination module is used to determine the average error between each of the function values ​​and the lidar measurement signal output by the second visibility meter, and then construct a target joint relation model using the lidar equation and based on the lidar ratio to be processed and the extinction coefficient to be processed corresponding to the average error. Then, a parameter mapping relation lookup table is generated using the target joint relation model. The signal strength determination module is used to acquire the signal strength corresponding to the target distance using a visibility measurement device set at the near-field target distance of the lidar, and to determine the target lidar ratio and target extinction coefficient based on the parameter mapping relationship lookup table and the signal strength; the target distance is the distance corresponding to the nearest distance to the near-field of the lidar in each of the distance databases; The visibility profile generation module is used to determine each extinction coefficient to be processed based on the laser path corresponding to the lidar echo signal, the target extinction coefficient and the target lidar ratio using the fernald inversion algorithm, so as to determine the visibility profile corresponding to the laser path based on each of the extinction coefficients to be processed.

9. An electronic device, characterized in that, include: Memory, used to store computer programs; A processor for executing the computer program to implement the visibility inversion method for lidar as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, Used to store a computer program, wherein the computer program, when executed by a processor, implements the visibility inversion method for lidar as described in any one of claims 1 to 7.

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