Highway vehicle and license plate recognition analysis method based on radio frequency perception

Abstract

The invention discloses an expressway vehicle and license plate recognition analysis method based on radio frequency perception, and relates to the technical field of vehicle management. The expressway vehicle and license plate recognition analysis method based on radio frequency perception comprises the following steps: license plate recognition interference assessment; evaluating license plate validity interference; and evaluating license plate integrity interference. Whether license plate validity interference evaluation is carried out is judged through the license plate recognition interference value, then the license plate recognition validity interference value is obtained based on the signal propagation path length and the license plate recognition interference value, and whether validity adjustment is carried out is judged. And finally, obtaining a license plate recognition integrity interference value according to the vehicle license plate recognition integrity data and the license plate recognition validity interference value, and judging whether to carry out integrity adjustment or not, thereby achieving the effect of improving the data accuracy in the medium license plate and vehicle discrimination and matching process. The problem that in the prior art, data accuracy is low in the medium license plate and vehicle screening and matching process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle management, and in particular to a highway vehicle and license plate recognition and analysis method based on radio frequency sensing. Background Art

[0002] During the process of passing through the highway, the license plate recorded in the passing medium, such as the ETC (Electronic Toll Collection) card, is inconsistent with the license plate hung on the actual passing vehicle. In the toll collection system, the passing flow and the license plate recognition flow cannot match. Taking the entrance flow as an example, if there is no toll flow and license plate recognition flow with the same license plate in the same toll lane within three minutes, it is considered that the medium license plate does not match the actual one. Guangdong Province has nearly 400,000 license plate mismatch data every day, of which 216,000 are toll flow that cannot match the license plate recognition, and 181,000 are license plate recognition flow that cannot match the toll record, accounting for about 3% of the total traffic. The main reasons for this phenomenon include: license plate recognition error, passing medium license plate error, or both. Among them, license plate recognition errors are caused by objective factors such as illumination and occlusion of the recognition equipment, which does not hinder the normal operation of the highway; but if the license plate of the passing medium does not match, it is easy to cause the wrong collection or omission of fees, and even breed various illegal phenomena such as evasion of fees and evasion of supervision. If it is not discovered in time, it may affect the normal operation of the highway. United Electric Service Company has built an on-the-way vehicle engine, which digitally monitors all vehicles on the Guangdong Provincial Expressway Network by integrating traffic data and license plate recognition data. If the media license plate does not match the actual one and cannot be identified and processed in real time, one vehicle will be identified as two, affecting the reliability of the system. At the same time, if the intelligent matching of inconsistent media license plates and visual recognition license plates cannot be achieved, even if abnormal vehicles are detected through the traffic flow algorithm, it will be difficult for the operating unit to make effective control.

[0003] The basic idea of ​​RF sensing technology is to embed an intelligent detection system in the RF device, which can monitor the spectrum conditions over a large area and identify unoccupied frequency bands for communication. This technology can improve spectrum utilization and adjust the transmission power or modulation mode to avoid interference when the legal user of the frequency band is detected to resume communication.

[0004] Existing vehicle and license plate recognition and matching methods mainly process images by graying and binarizing them to improve the accuracy of license plate recognition, use image processing algorithms or deep learning models to accurately find the location of the license plate in the image, and compare the recognized license plate information with the records in the database to determine whether the license plate matches the actual vehicle. License plate recognition technology is greatly affected by image quality. If the license plate in the image is blurred, blocked, or there are other interference factors (such as insufficient light, overexposure, etc.), the recognition accuracy will decrease.

[0005] For example, the invention patent with announcement number: CN106652469B announces a vehicle entry and vehicle exit license plate recognition method and license plate recognition system, including: initial recognition of the license plate of the vehicle entering the site to obtain initial license plate number recognition information; determine whether the initial license plate number recognition information is the same as a license plate number in the fixed vehicle list; if so, open the gate to let it go; otherwise, determine whether the matching degree between the initial license plate number recognition information and a specific record in the fixed vehicle list reaches a threshold; if not, determine it to be a temporary vehicle and open the gate to let it go; if so, extract feature information of the license plate area; determine whether the matching degree between the feature information of the license plate area and the pre-stored feature information reaches a threshold; if so, open the gate to let it go; if not, determine it to be a temporary vehicle and record it, then open the gate to let it go.

[0006] For example, a license plate recognition method is announced in the invention patent with announcement number: CN112712706B, including: obtaining a first license plate number to be matched; a vehicle identification device collects physical license plate information and electronic license plate information; the physical license plate information and the electronic license plate information include at least the license plate number; judging whether the physical license plate information and the electronic license plate information completely match; if so, determining that the vehicle is a legal vehicle; if not, judging whether the physical license plate information and the electronic license plate information have less than two characters that do not match; if not, determining that the vehicle is an illegal vehicle; if so, determining whether the license plate is a legal vehicle through lane information and vehicle color.

[0007] However, in the process of implementing the technical solution of the invention in the embodiments of the present application, the present application found that the above technology has at least the following technical problems:

[0008] In the prior art, due to anomalies in radio frequency communication and gantry flow when recording vehicle and license plate information, the license plate recognition flow information data is missing and erroneous, resulting in low data accuracy during the process of medium license plate and vehicle identification and matching. Summary of the invention

[0009] The embodiments of the present application solve the problem of low data accuracy in the process of medium license plates and vehicle identification and matching in the prior art by providing a highway vehicle and license plate recognition and analysis method based on radio frequency sensing, thereby improving the data accuracy in the process of medium license plates and vehicle identification and matching.

[0010] The embodiment of the present application provides a highway vehicle and license plate recognition analysis method based on radio frequency sensing, comprising the following steps: S1, obtaining vehicle license plate recognition data based on gantry license plate recognition flow information to obtain a license plate recognition interference value, judging whether to perform a license plate validity interference evaluation based on the license plate recognition interference value, the license plate recognition interference value being used to evaluate the interference situation of the vehicle's license plate recognition at a preset time point; S2, obtaining a license plate recognition validity interference value based on the signal propagation path length obtained from the gantry license plate recognition flow information and a license plate recognition interference value not higher than the preset license plate recognition interference value, judging whether to perform an effectiveness adjustment based on the license plate recognition effectiveness interference value, the license plate recognition effectiveness interference value being used to evaluate the interference situation of the vehicle's license plate recognition effectiveness at a preset time point; S3, obtaining a license plate recognition integrity interference value based on the vehicle license plate recognition integrity data obtained from the gantry license plate recognition flow information and the license plate recognition effectiveness interference value after effectiveness adjustment, judging whether to perform an integrity adjustment based on the license plate recognition integrity interference value, the license plate recognition integrity interference value being used to evaluate the interference situation of the vehicle's license plate recognition integrity at a preset time point.

[0011] Furthermore, the vehicle license plate recognition data includes license plate image length, license plate image width, horizontal pixel number, vertical pixel number, exposure value, horizontal pixel light intensity and vertical pixel light intensity; the vehicle license plate recognition integrity data includes signal frequency and path distance.

[0012] Further, the license plate recognition interference value is obtained by a horizontal pixel error value, a vertical pixel error value, a horizontal brightness error value and a vertical brightness error value; the horizontal pixel error value is represented by a result of a ratio operation between an initial horizontal pixel difference value and a preset horizontal pixel threshold value obtained from a database; the initial horizontal pixel difference value is represented by a result of a difference operation between a preset horizontal pixel threshold value and a license plate image length and a horizontal pixel number; the vertical pixel error value is represented by a result of a ratio operation between an initial vertical pixel difference value and a preset vertical pixel threshold value obtained from a database; the initial vertical pixel difference value is represented by a result of a difference operation between a preset vertical pixel threshold value and a license plate image width and a vertical pixel number; The horizontal brightness error value is represented by the result of a ratio operation between the initial horizontal brightness difference value and a preset horizontal brightness threshold obtained from a database; the initial horizontal brightness difference value is represented by the result of a difference operation between the preset horizontal brightness threshold and the initial horizontal brightness value; the initial horizontal brightness value is represented by the result of a product operation between the exposure value and the average of the horizontal pixel light intensities; the vertical brightness error value is represented by the result of a ratio operation between the initial vertical brightness difference value and the preset vertical brightness threshold obtained from a database; the initial vertical brightness difference value is represented by the result of a difference operation between the preset vertical brightness threshold and the initial vertical brightness value; the initial vertical brightness value is represented by the result of a product operation between the exposure value and the average of the vertical pixel light intensities.

[0013] Furthermore, the license plate recognition effectiveness interference value is obtained by a delay spread error value and a license plate recognition interference value that is not higher than a preset license plate recognition interference value; the delay spread error value is represented by the result of a ratio operation between an initial delay spread difference and a preset delay spread threshold obtained from a database; the initial delay spread difference is represented by the result of a difference operation between the ratio of the signal propagation path length and the speed of light obtained from the database and the preset delay spread threshold.

[0014] Furthermore, the license plate recognition integrity interference value is obtained by the distance loss error value, the signal frequency loss error value and the license plate recognition effectiveness interference value after effectiveness adjustment; the distance loss error value is represented by the result of a ratio operation between an initial distance loss difference and a preset path loss threshold obtained from a database; the initial distance loss difference is represented by the result of a difference operation between a path distance and a preset path loss threshold after logarithmic operation; the signal frequency loss error value is represented by the result of a ratio operation between an initial frequency loss difference and a preset signal frequency loss threshold obtained from a database; the initial frequency loss difference is represented by the result of a difference operation between a signal frequency and a preset signal frequency loss threshold after logarithmic operation.

[0015] Furthermore, the restriction expression of the license plate recognition interference value is as follows:

[0016]

[0017]

[0018]

[0019]

[0020]

[0021] Where, TS w represents the license plate recognition interference value of the license plate at the wth preset time point, w=1,2,...,a, w represents the number of the preset time point, a represents the total number of preset time points, SP w represents the horizontal pixel error value of the license plate at the wth preset time point, CP w Indicates the vertical pixel error value of the license plate at the wth preset time point, IX w Indicates the horizontal brightness error value of the license plate at the wth preset time point, IY w Indicates the vertical brightness error value of the license plate at the wth preset time point, LX w represents the length of the license plate image at the wth preset time point, LY w Indicates the width of the license plate image at the wth preset time point, NX w Indicates the number of horizontal pixels of the license plate at the wth preset time point, NY w represents the number of vertical pixels of the license plate at the wth preset time point, E w represents the exposure value of the license plate at the wth preset time point, X mw represents the horizontal pixel intensity of the mth pixel in the horizontal direction of the license plate image at the wth preset time point, m = 1, 2, ..., b, m represents the number of the horizontal pixel in the license plate image, b represents the total number of horizontal pixels in the license plate image, Y nw represents the vertical pixel light intensity of the nth pixel in the vertical direction of the license plate image at the wth preset time point, n = 1, 2, ..., k, n represents the number of the vertical pixel in the license plate image, k represents the total number of vertical pixel in the license plate image, SP 0 Indicates the preset horizontal pixel threshold, CP 0 Indicates the preset vertical pixel threshold, IX 0 Indicates the preset horizontal brightness threshold, IY 0 represents a preset vertical brightness threshold, e represents a natural constant, ΔSP represents a reference horizontal pixel range, ΔCP represents a reference vertical pixel range, ΔIX represents a reference horizontal brightness range, and ΔIY represents a reference vertical brightness range.

[0022] Furthermore, the path distance represents the distance between the license plate and the gantry during the gantry recognition process; the signal propagation path length represents the maximum path length of the signal propagation during the gantry recognition of the license plate; the horizontal pixel number represents the number of pixels in the horizontal direction in the license plate image during the gantry recognition process; the vertical pixel number represents the number of pixels in the vertical direction in the license plate image during the gantry recognition process.

[0023] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0024] 1. Determine whether to conduct a license plate validity interference assessment through the license plate recognition interference value, then obtain the license plate recognition validity interference value through the signal propagation path length and the license plate recognition interference value that is not higher than the preset license plate recognition interference value, and determine whether to make an validity adjustment. Finally, obtain the license plate recognition integrity interference value through the vehicle license plate recognition integrity data and the license plate recognition validity interference value after the validity adjustment, and determine whether to make an integrity adjustment, thereby improving the accuracy of medium license plate and vehicle identification and matching, and further improving the data accuracy in the process of medium license plate and vehicle identification and matching, effectively solving the problem of low data accuracy in the process of medium license plate and vehicle identification and matching in the prior art.

[0025] 2. The license plate recognition interference value is obtained through the horizontal pixel error value, vertical pixel error value, horizontal brightness error value and vertical brightness error value, and then the license plate recognition effectiveness interference value is obtained through the delay spread error value and the license plate recognition interference value not higher than the preset license plate recognition interference value. Finally, the license plate recognition integrity interference value is obtained through the distance loss error value, the signal frequency loss error value and the license plate recognition effectiveness interference value after effectiveness adjustment, thereby achieving the improvement of the accuracy of the data related to the medium license plate and vehicle identification and matching, and then achieving the improvement of the reliability of the medium license plate and vehicle identification and matching.

[0026] 3. By judging whether the license plate recognition interference value is not higher than the preset license plate recognition interference value, and then judging whether the license plate recognition validity interference value meets the validity condition, and then judging whether the license plate recognition integrity interference value meets the integrity condition, dynamic adjustment of the medium license plate and vehicle identification and matching is achieved, thereby achieving a comprehensive improvement in the medium license plate and vehicle identification and matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A flowchart of a highway vehicle and license plate recognition and analysis method based on radio frequency sensing provided in an embodiment of the present application;

[0028] Figure 2 A statistical diagram of changes in the signal propagation path length-delay spread error value provided in an embodiment of the present application;

[0029] Figure 3 An overall flow chart provided for an embodiment of the present application. DETAILED DESCRIPTION

[0030] The embodiment of the present application solves the problem of low data accuracy in the prior art during medium license plate and vehicle identification and matching by providing a highway vehicle and license plate recognition analysis method based on radio frequency sensing. The license plate recognition interference value is obtained by obtaining vehicle license plate recognition data, and whether to perform license plate validity interference evaluation is determined based on the license plate recognition interference value. Then, the license plate recognition validity interference value is obtained according to the signal propagation path length obtained from the gantry license plate recognition flow information and the license plate recognition interference value that is not higher than the preset license plate recognition interference value. Based on the license plate recognition validity interference value, it is determined whether to perform validity adjustment. Finally, the license plate recognition integrity interference value is obtained according to the vehicle license plate recognition integrity data obtained from the gantry license plate recognition flow information and the license plate recognition validity interference value after validity adjustment. Based on the license plate recognition integrity interference value, it is determined whether to perform integrity adjustment, thereby improving data accuracy in the medium license plate and vehicle identification and matching process.

[0031] The technical solution in the embodiment of the present application is to solve the problem of low data accuracy in the process of identifying and matching the above-mentioned medium license plate and vehicle. The overall idea is as follows:

[0032] The license plate recognition interference value is used to determine whether to conduct a license plate validity interference assessment, and then the license plate recognition validity interference value is obtained based on the signal propagation path length and the license plate recognition interference value that is not higher than the preset license plate recognition interference value, and it is determined whether to make an effectiveness adjustment. Finally, the license plate recognition integrity interference value is obtained based on the vehicle license plate recognition integrity data and the license plate recognition validity interference value after the effectiveness adjustment, and it is determined whether to make an integrity adjustment, thereby achieving the effect of improving the data accuracy in the process of medium license plate and vehicle identification and matching.

[0033] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0034] like Figure 1As shown, it is a flow chart of a highway vehicle and license plate recognition analysis method based on radio frequency sensing provided by an embodiment of the present application, and the method includes the following steps: S1, license plate recognition interference evaluation: based on the gantry license plate recognition flow information, the vehicle license plate recognition data is obtained to obtain the license plate recognition interference value, and based on the license plate recognition interference value, it is judged whether to perform a license plate validity interference evaluation, the vehicle license plate recognition data is used to reflect the license plate recognition status of the vehicle at a preset time point, and the license plate recognition interference value is used to evaluate the interference status of the license plate recognition of the vehicle at a preset time point; S2, license plate validity interference evaluation: according to the signal propagation path length obtained from the gantry license plate recognition flow information and the license plate recognition interference value not higher than the preset license plate recognition interference value, the license plate recognition validity interference value is obtained, and based on the license plate recognition validity interference value, it is judged whether to perform a license plate recognition validity interference evaluation. Determine whether to make an effectiveness adjustment. The license plate recognition effectiveness interference value is used to evaluate the interference with the vehicle's license plate recognition effectiveness at a preset time point, and the effectiveness adjustment is used to improve the effectiveness of the vehicle's license plate recognition effectiveness data; S3, license plate integrity interference evaluation: obtain the license plate recognition integrity interference value based on the vehicle license plate recognition integrity data obtained from the gantry license plate recognition flow information and the license plate recognition effectiveness interference value after effectiveness adjustment, and determine whether to make an integrity adjustment based on the license plate recognition integrity interference value. The vehicle license plate recognition integrity data is used to reflect the vehicle's license plate recognition integrity at a preset time point, and the license plate recognition integrity interference value is used to evaluate the interference with the vehicle's license plate recognition integrity at a preset time point, and the integrity adjustment is used to improve the integrity of the vehicle's license plate recognition effectiveness data.

[0035] In this embodiment, the gantry license plate recognition flow information is obtained by transmitting the license plate image to the license plate recognizer through the network through the gantry high-definition camera. The license plate recognizer automatically recognizes the vehicle's license plate color and license plate number based on the dynamic video captured by the front-end high-definition camera. Subsequently, the license plate recognition management software (such as traffic control 12123, etc.) or the radio frequency recognition method collects the recognition results of each license plate recognizer in real time. In the field of license plate recognition, the radio frequency recognition method can be used to collect the recognition results of the license plate recognizer in real time, including information such as time, location, direction and license plate number, and save them in a local dedicated server.

[0036] There is a close mutual influence relationship between the license plate recognition interference value, the license plate recognition validity interference value and the license plate recognition integrity interference value. The higher the license plate recognition interference value, the higher the license plate recognition validity interference value and the license plate recognition integrity interference value, because the higher the license plate recognition interference value means that there are more uncertainties or errors in the license plate recognition process, and some license plate information cannot be correctly recognized, thus affecting the integrity; the data accuracy is improved in the process of medium license plate and vehicle identification and matching.

[0037] It should be supplemented that the vehicle license plate recognition data includes the license plate image length, license plate image width, horizontal pixel number, vertical pixel number, exposure value, horizontal pixel light intensity and vertical pixel light intensity; the horizontal pixel number indicates the number of pixels in the horizontal direction of the license plate image during the gantry recognition process; the vertical pixel number indicates the number of pixels in the vertical direction of the license plate image during the gantry recognition process; the vehicle license plate recognition integrity data includes signal frequency and path distance; the path distance indicates the distance between the license plate and the gantry during the gantry recognition process; the signal propagation path length indicates the maximum path length of signal propagation during the gantry recognition of the license plate.

[0038] Specifically, the license plate image is captured by the gantry HD camera, and the license plate area is identified by image processing technology (such as edge detection and morphological processing). According to the screened license plate area, its bounding box is determined, and the license plate image length, license plate image width and signal frequency of the license plate image are obtained according to the coordinates of the bounding box. The exposure value is usually related to the setting and shooting environment of the gantry HD camera. The exposure value can be obtained from the configuration information of the gantry HD camera.

[0039] Image processing software such as OpenCV (Open Source Computer Vision Library) usually provides a function for reading pixel brightness values, and the horizontal pixel number, vertical pixel number, horizontal pixel intensity and vertical pixel intensity of the license plate image are obtained through the image processing software.

[0040] The image processing software is used to analyze the changes in size and shape of the vehicle image and the changes in the camera's viewing angle to obtain the path distance. The time difference between the electromagnetic signal from the camera to the preset server during the gantry's license plate recognition process is measured by a timer, and then combined with the speed of light to obtain the signal propagation path length. This signal represents the electromagnetic signal during the gantry's license plate recognition process. This improves the accuracy of data related to the identification and matching of media license plates and vehicles, thereby improving the accuracy of data during the identification and matching of media license plates and vehicles.

[0041] Furthermore, the license plate recognition interference value is obtained by the horizontal pixel error value, the vertical pixel error value, the horizontal brightness error value and the vertical brightness error value; the horizontal pixel error value is used to reflect the deviation degree of the pixel size in the horizontal direction of the license plate image at a preset time point, and the horizontal pixel error value (i.e., the SP in the restriction expression of the license plate recognition interference value) is the value of the horizontal pixel error value. w) is represented by the result of the ratio operation between the initial horizontal pixel difference and the preset horizontal pixel threshold obtained from the database; the initial horizontal pixel difference is represented by the result of the difference operation between the preset horizontal pixel threshold and the ratio of the license plate image length and the number of horizontal pixels; the vertical pixel error value is used to reflect the degree of deviation of the pixel size in the vertical direction of the license plate image at a preset time point. The vertical pixel error value (i.e., the CP in the limiting expression of the license plate recognition interference value) is w ) is represented by the result of the ratio operation between the initial vertical pixel difference and the preset vertical pixel threshold obtained from the database; the initial vertical pixel difference is represented by the result of the difference operation between the preset vertical pixel threshold and the ratio of the license plate image width and the number of vertical pixels; the horizontal brightness error value is used to reflect the degree of deviation of the brightness of the horizontal pixels in the license plate image at a preset time point. The horizontal brightness error value (i.e., the IX in the limiting expression of the license plate recognition interference value) w ) is represented by the result of the ratio operation between the initial horizontal brightness difference value and the preset horizontal brightness threshold obtained from the database; the initial horizontal brightness difference value is represented by the result of the difference operation between the preset horizontal brightness threshold and the initial horizontal brightness value; the initial horizontal brightness value is represented by the result of the product operation between the exposure value and the average value of the horizontal pixel light intensity; the vertical brightness error value (i.e., IY in the restriction expression of the license plate recognition interference value) w ) is used to reflect the degree of deviation of the brightness of pixels in the vertical direction in the license plate image at a preset time point. The vertical brightness error value is represented by the result of a ratio operation between the initial vertical brightness difference value and a preset vertical brightness threshold obtained from the database; the initial vertical brightness difference value is represented by the result of a difference operation between the preset vertical brightness threshold and the initial vertical brightness value; the initial vertical brightness value is represented by the result of a product operation between the exposure value and the average of the vertical pixel light intensities.

[0042] Among them, the restriction expression of license plate recognition interference value is as follows:

[0043]

[0044]

[0045]

[0046]

[0047]

[0048] Where, TS w represents the license plate recognition interference value of the license plate at the wth preset time point, w=1,2,...,a, w represents the number of the preset time point, a represents the total number of preset time points, SP wrepresents the horizontal pixel error value of the license plate at the wth preset time point, CP w Indicates the vertical pixel error value of the license plate at the wth preset time point, IX w Indicates the horizontal brightness error value of the license plate at the wth preset time point, IY w Indicates the vertical brightness error value of the license plate at the wth preset time point, LX w represents the length of the license plate image at the wth preset time point, LY w Indicates the width of the license plate image at the wth preset time point, NX w Indicates the number of horizontal pixels of the license plate at the wth preset time point, NY w represents the number of vertical pixels of the license plate at the wth preset time point, E w represents the exposure value of the license plate at the wth preset time point, X mw represents the horizontal pixel intensity of the mth pixel in the horizontal direction of the license plate image at the wth preset time point, m = 1, 2, ..., b, m represents the number of the horizontal pixel in the license plate image, b represents the total number of horizontal pixels in the license plate image, Y nw represents the vertical pixel light intensity of the nth pixel in the vertical direction of the license plate image at the wth preset time point, n = 1, 2, ..., k, n represents the number of the vertical pixel in the license plate image, k represents the total number of vertical pixel in the license plate image, SP 0 Indicates the preset horizontal pixel threshold, CP 0 Indicates the preset vertical pixel threshold, IX 0 Indicates the preset horizontal brightness threshold, IY 0 represents a preset vertical brightness threshold, e represents a natural constant, ΔSP represents a reference horizontal pixel range, ΔCP represents a reference vertical pixel range, ΔIX represents a reference horizontal brightness range, and ΔIY represents a reference vertical brightness range.

[0049] In this embodiment, the aforementioned database is a database for storing various types of setting data established before the design of the highway vehicle and license plate recognition and analysis method based on radio frequency sensing provided in the embodiment of the present application. The database includes but is not limited to image brightness, number of image pixels, horizontal pixel light intensity, etc., and the various numerical values ​​therein are directly set by technical personnel. For example, the preset horizontal pixel threshold is represented by the maximum value of the horizontal pixels of the license plate image in the historical time period in the database, the preset vertical pixel threshold is represented by the maximum value of the vertical pixels of the license plate image in the historical time period in the database, the preset horizontal brightness threshold is represented by the maximum value of the horizontal brightness of the license plate image in the historical time period in the database, and the preset vertical brightness threshold is represented by the maximum value of the vertical brightness of the license plate image in the historical time period in the database.

[0050] It should be supplemented that, when the reference horizontal pixel range ΔSP is greater than 0, when ΔSP is less than or equal to 0, it is regarded as having a small degree of interference to license plate recognition, and the influence of the horizontal pixel error value is not considered; when the reference vertical pixel range ΔCP is greater than 0, when ΔCP is less than or equal to 0, it is regarded as having a small degree of interference to license plate recognition, and the influence of the vertical pixel error value is not considered; when the reference horizontal brightness range ΔIX is greater than 0, when ΔIX is less than or equal to 0, it is regarded as having a small degree of interference to license plate recognition, and the influence of the horizontal brightness error value is not considered; when the reference vertical brightness range ΔIY is greater than 0, when ΔIY is less than or equal to 0, it is regarded as having a small degree of interference to license plate recognition, and the influence of the vertical brightness error value is not considered.

[0051] It should be understood that the algorithm of this embodiment combines the vehicle license plate recognition data for comprehensive analysis to obtain the license plate recognition interference value. The vehicle license plate recognition data in the algorithm of this embodiment does not exist independently, but is interrelated. The length and width of the license plate image reflect the size of the image. The smaller the image size, the more incomplete the license plate character information may be, which increases the difficulty of recognition, and thus increases the license plate recognition interference value. The exposure value affects the brightness of the image. The lower the exposure, the image may be too dark and the characters may be difficult to recognize, which in turn increases the license plate recognition interference value. The exposure value increases and the image becomes brighter as a whole, which may cause the horizontal pixel intensity and the vertical pixel intensity to increase accordingly. The number of horizontal pixels and the number of vertical pixels directly determine the resolution of the image. The higher the resolution of the image, the more details it can provide, resulting in a reduction in the license plate recognition interference value. The parameters of the algorithm of this embodiment need to be considered together and at the same time to influence the results.

[0052] Specifically, assuming that the horizontal pixel error value SP w The range is 0.5-1, the vertical pixel error value CP w The range is 0.5-1, and the horizontal brightness error value is IX w The range is 0.5-1, the vertical brightness error value IY w The range is 0.5-1, as shown in Table 1, which is a statistical table of changes in license plate recognition interference values:

[0053] Table 1 Statistics of changes in license plate recognition interference values

[0054]

[0055]

[0056] As can be seen from the table above, as the horizontal pixel error value SP w , vertical pixel error value CP w , horizontal brightness error value IX w And the vertical brightness error value IY wAs the value increases, the license plate recognition interference value also increases, which means that the license plate recognition interference of the vehicle gradually increases; the accurate quantification of the vehicle's license plate recognition situation is achieved, thereby improving the data accuracy in the process of medium license plate and vehicle identification and matching.

[0057] Furthermore, the license plate recognition validity interference value is obtained by the delay spread error value and the license plate recognition interference value that is not higher than the preset license plate recognition interference value; the delay spread error value is used to reflect the delay spread deviation when the license plate at the preset time point is recognized by the gantry; the delay spread error value (i.e., the SY in the restriction expression of the license plate recognition validity interference value) w ) is represented by the result of a ratio operation between an initial delay spread difference and a preset delay spread threshold obtained from a database; the initial delay spread difference is represented by the result of a difference operation between the ratio of the signal propagation path length and the speed of light obtained from a database and a preset delay spread threshold.

[0058] Among them, the limiting expression of the license plate recognition validity interference value is as follows:

[0059]

[0060]

[0061] In the formula, YX w represents the license plate recognition validity interference value at the wth preset time point, w=1,2,...,a, w represents the number of the preset time point, a represents the total number of preset time points, SY w represents the delay spread error value of the license plate at the wth preset time point, TS w ′ represents the license plate recognition interference value that is not higher than the preset license plate recognition interference value at the wth preset time point, D w represents the signal propagation path length of the license plate at the wth preset time point, c represents the speed of light, SY 0 represents the preset delay spread threshold, e represents the natural constant, and ΔSY represents the reference delay spread range.

[0062] It should be added that the specific acquisition process of judging whether to conduct a license plate validity interference assessment based on the license plate recognition interference value is as follows: judge whether the license plate recognition interference value is not higher than the preset license plate recognition interference value: when the license plate recognition interference value is not higher than the preset license plate recognition interference value, it indicates that the license plate recognition interference level is qualified, and a license plate validity interference assessment is performed; when the license plate recognition interference value is higher than the preset license plate recognition interference value, it indicates that the license plate recognition interference level is unqualified, and a recognition error prompt is sent to the preset personnel.

[0063] In this embodiment, the preset delay spread threshold is represented by the maximum value of the delay spread of the license plate image signal in the historical time period in the database, and the preset license plate recognition interference value is represented by the maximum value of the license plate recognition interference value in the historical time period in the database. The reference delay spread range ΔSY is greater than 0. When ΔSY is less than or equal to 0, it is considered that the degree of interference to the effectiveness of license plate recognition is small, and the influence of the delay spread error value is not considered.

[0064] It should be understood that the algorithm of this embodiment combines the length of the signal propagation path and the vehicle license plate recognition data for comprehensive analysis to obtain the license plate recognition effectiveness interference value. In the algorithm of this embodiment, the length of the signal propagation path and the vehicle license plate recognition data do not exist independently, but are interrelated. The length of the signal propagation path will affect the quality of the signal, including the strength, clarity and stability of the signal. As the length of the signal propagation path increases, the resolution and brightness of the license plate image may gradually decrease, and the pixel light intensity may also weaken due to signal attenuation. The signal will be attenuated and interfered during the propagation process, resulting in a decrease in image quality. The longer the signal propagation path, the greater the possibility of signal attenuation, thereby reducing the accuracy of license plate recognition, which in turn leads to an increase in the license plate recognition effectiveness interference value. The parameters of the algorithm of this embodiment need to be considered together and simultaneously in their impact on the results.

[0065] Specifically, assuming that the signal propagation path length D w The range is 50-100 (m), and the preset delay spread threshold SY 0 Fixed to 1*10 -7 (s), the speed of light is fixed at 3*10 8 (m / s), such as Figure 2 As shown, it is a statistical diagram of the change of the signal propagation path length-delay spread error value provided by the embodiment of the present application, which is Figure 2 It can be seen that as the signal propagation path length D w The delay spread error value gradually increases, which means that the delay spread deviation when the license plate is recognized by the gantry gradually increases, and the vehicle's license plate recognition effectiveness is more obviously interfered with. The accurate quantification of the delay spread deviation when the license plate is recognized by the gantry is achieved, thereby improving the data accuracy in the process of medium license plate and vehicle identification and matching.

[0066] Furthermore, the specific process of determining whether to make an effectiveness adjustment is as follows: Step one, determining whether the license plate recognition effectiveness interference value meets the effectiveness condition, if so, no effectiveness adjustment is made, otherwise step two is executed, the effectiveness condition indicates that the license plate recognition effectiveness interference value is not higher than the preset recognition effectiveness interference threshold obtained from the database; Step two, performing spectrum resource optimization, when the monitored effectiveness interference value meets the effectiveness condition, stop making effectiveness interference, otherwise step three is executed, spectrum resource optimization indicates improving the utilization rate of spectrum resources through dynamic spectrum access methods; Step three, performing lighting impact compensation, when the monitored effectiveness interference value meets the effectiveness condition, stop making effectiveness interference, otherwise a recognition error prompt is sent to the preset personnel, lighting impact compensation indicates reducing the impact of lighting on license plate recognition through infrared recognition methods.

[0067] In this embodiment, the preset recognition validity interference threshold is represented by the maximum value of the license plate recognition validity interference value in the historical time period in the database. License plate recognition plays an important role in traffic management, security monitoring, road toll collection and other fields. The grayscale image of the vehicle is collected by an infrared camera. The dynamic spectrum access method can improve the spectrum utilization efficiency by utilizing idle spectrum resources when radio spectrum resources are limited. Due to the characteristics of infrared rays, the vehicle can only see the license plate in the image. The reflective characteristics of the license plate make it contrast sharply with the background under infrared light. The license plate area can be accurately located through image processing technology (such as edge detection and morphological processing); the data accuracy is improved in the process of medium license plate and vehicle identification and matching.

[0068] Furthermore, the license plate recognition integrity interference value is obtained by the distance loss error value, the signal frequency loss error value and the license plate recognition effectiveness interference value after effectiveness adjustment; the distance loss error value is used to reflect the loss deviation of the signal path at a preset time point; when the path distance is greater than the preset path distance threshold obtained from the database, the distance loss error value (i.e., the LP in the restriction expression of the license plate recognition integrity interference value) is w ) is represented by the result of the ratio operation between the initial distance loss difference and the preset path loss threshold obtained from the database; the initial distance loss difference is represented by the result of the difference operation between the path distance and the preset path loss threshold after the logarithmic operation, and when the path distance is less than or equal to the preset path distance threshold obtained from the database, the distance loss error value is recorded as 0; the signal frequency loss error value is used to reflect the loss deviation of the signal frequency at a preset time point; when the signal frequency is greater than the preset signal frequency threshold, the signal frequency loss error value (i.e., fP in the limiting expression of the license plate recognition integrity interference value) is w) is represented by the result of a ratio operation between the initial frequency loss difference and a preset signal frequency loss threshold obtained from a database; the initial frequency loss difference is represented by the result of a difference operation between the signal frequency and the preset signal frequency loss threshold after a logarithmic operation is performed on the signal frequency; when the signal frequency is less than or equal to the preset signal frequency threshold obtained from the database, the signal frequency loss error is recorded as 0.

[0069] Among them, the limiting expression of the license plate recognition integrity interference value is as follows:

[0070]

[0071]

[0072]

[0073] Where WZ w represents the license plate recognition integrity interference value of the license plate at the wth preset time point, w=1,2,...,a, w represents the number of the preset time point, a represents the total number of preset time points, LP w represents the distance loss error value of the license plate at the wth preset time point, fP w represents the signal frequency loss error value of the license plate at the wth preset time point, YX w ′ represents the license plate recognition validity interference value after the validity adjustment of the license plate at the wth preset time point, f w represents the signal frequency of the license plate at the wth preset time point, L w represents the path distance of the license plate at the wth preset time point, LP 0 represents the preset path loss threshold, fP 0 represents the preset signal frequency loss threshold, e represents the natural constant, ΔLP represents the reference path loss range, ΔfP represents the reference signal frequency loss range, L 0 represents the preset path distance threshold, f 0 Indicates the preset signal frequency threshold.

[0074] In this embodiment, the preset path loss threshold is represented by the maximum value of the path loss corresponding to the license plate image signal in the historical time period in the database, the preset signal frequency loss threshold is represented by the maximum value of the signal frequency loss corresponding to the license plate image signal in the historical time period in the database, the preset path distance threshold is represented by the maximum value of the path distance corresponding to the license plate image signal in the historical time period in the database, and the preset signal frequency threshold is represented by the maximum value of the signal frequency corresponding to the license plate image signal in the historical time period in the database. The reference path loss range ΔLP is greater than 0. When ΔLP is less than or equal to 0, it is considered that the degree of interference with the integrity of the license plate recognition is small, and the influence of the distance loss error value is not considered; the reference signal frequency loss range ΔfP is greater than 0. When ΔfP is less than or equal to 0, it is considered that the degree of interference with the integrity of the license plate recognition is small, and the influence of the signal frequency loss error value is not considered; when the path distance is less than or equal to the preset path distance threshold, the influence of the path distance on the distance loss error value is not considered; when the signal frequency is less than or equal to the preset signal frequency threshold, the influence of the signal frequency on the signal frequency loss error value is not considered.

[0075] It should be understood that the algorithm of this embodiment combines the vehicle license plate recognition integrity data and the license plate recognition validity interference value for comprehensive analysis to obtain the license plate recognition integrity interference value. In the algorithm of this embodiment, the vehicle license plate recognition integrity data and the license plate recognition validity interference value do not exist independently, but are interrelated. The higher the signal frequency, the more power consumption of the device may increase, or even generate signal interference, which in turn affects the validity of the license plate recognition, and thus increases the license plate recognition integrity interference value. The increase in the path distance will aggravate the signal attenuation and interference, resulting in a decrease in the quality of the license plate image, which in turn affects the accuracy of the license plate recognition. The change in the path distance may also cause the size of the license plate image to change, which indirectly leads to an increase in the license plate recognition validity interference value. The increase in the license plate recognition validity interference value means that the license plate recognition system is affected by more interference factors, which may lead to a decrease in the quality of the license plate image, a slowdown in the recognition speed, or an increase in the recognition error rate. These changes will indirectly affect the accuracy of the vehicle license plate recognition integrity data, thereby increasing the license plate recognition integrity interference value. The parameters of the algorithm of this embodiment need to consider the impact on the results together at the same time; the accurate quantification of the interference situation of the vehicle's license plate recognition integrity is achieved, and the data accuracy is improved in the process of medium license plate and vehicle identification and matching.

[0076] Furthermore, the specific process of judging whether to perform integrity adjustment based on the license plate recognition integrity interference value is as follows: the first step is to judge whether the license plate recognition integrity interference value meets the integrity condition. If so, no integrity adjustment is performed, otherwise the second step is executed. The integrity condition indicates that the license plate recognition integrity interference value is not higher than the preset recognition integrity threshold obtained from the database; the second step is to perform signal enhancement. When the monitored license plate recognition integrity interference value meets the integrity condition, the integrity interference is stopped, otherwise the third step is executed. Signal enhancement means enhancing the high-frequency component of the signal by the pre-emphasis method; the third step is to attenuate the low-frequency component. When the monitored license plate recognition integrity interference value meets the integrity condition, the integrity interference is stopped, otherwise an identification error prompt is sent to the preset personnel. The low-frequency component attenuation means attenuating the low-frequency component of the signal through the equalization circuit to restore the transmission line loss.

[0077] In this embodiment, the preset recognition integrity threshold is represented by the maximum value of the license plate recognition integrity interference value in the historical time period in the database. Pre-emphasis is a method of pre-processing the signal at the transmitting end, which aims to enhance the high-frequency component of the signal. Since the high-frequency component is more susceptible to attenuation than the low-frequency component during the transmission of the signal, the pre-emphasis technology compensates for this attenuation by increasing the amplitude of the high-frequency component at the transmitting end. The equalization circuit is used to compensate for the attenuation and distortion of the signal by the channel. When the transmission line attenuates the low-frequency component less, it may be necessary to attenuate the low-frequency component of the signal through the equalization circuit to restore the loss characteristics of the transmission line and improve the frequency response and overall quality of the signal; thus, the data accuracy is improved in the process of medium license plate and vehicle identification and matching.

[0078] like Figure 3 As shown, it is the overall flow chart provided by the embodiment of the present application. When the medium license plate does not match the actual one and cannot be identified and processed in real time, one vehicle will be identified as two vehicles, affecting the reliability of the system. At the same time, if the intelligent matching of the inconsistent medium license plate and the visual recognition license plate cannot be achieved, the medium license plate contains important information such as the vehicle identification number and registration area. Through this information, the public and relevant agencies can identify the ownership and management of the vehicle to ensure road safety and traffic order. The radio frequency communication of the passing medium may be abnormal and cause loss, and the license plate recognition may be missing or wrong due to illumination, occlusion and other reasons. The embodiment of the present application reduces the impact of data loss on the identification and matching of vehicles whose medium license plates do not match the actual one by monitoring the license plate recognition interference value, the license plate recognition validity interference value and the license plate recognition integrity interference value and performing validity adjustment and integrity adjustment; it achieves the improvement of data accuracy in the process of identifying and matching the medium license plate and the vehicle.

[0079] Since the gantry transaction flow belongs to the settlement system and undergoes splitting and verification, it has high accuracy. The matching rate between the gantry card recognition flow and the gantry split flow can be as high as about 90%, which also greatly proves the accuracy of the card recognition flow.

[0080] The matching of license plates and files has effectively improved the level of highway operation and management, as listed below:

[0081] 1. We discovered ETC vehicles whose license plates did not match each time they went on the road and whose matching visual license plates were highly consistent. We determined that the vehicles were suspected of having incorrect license plates, and our customer service staff will follow up and handle the matter.

[0082] 2. We discovered ETC vehicles that sometimes match but sometimes don’t, and when they don’t match, the visual license plates are relatively consistent (sometimes this happens more frequently with 2-3 license plates or more). These vehicles are likely to have mobile electronic tags, and ETC tags are used on multiple vehicles, so we focus on following up.

[0083] 3. We found that at some entrance toll stations, a large number of CPC (Composite Passage Card) vehicles often had license plates that did not match the regulations, which reflected problems in the operation and management of some highway entrances.

[0084] To summarize, the embodiment of the present application determines whether to perform a license plate validity interference evaluation through the license plate recognition interference value, then obtains the license plate recognition validity interference value through the signal propagation path length and the license plate recognition interference value that is not higher than the preset license plate recognition interference value and determines whether to perform a validity adjustment, and finally obtains the license plate recognition integrity interference value through the vehicle license plate recognition integrity data and the license plate recognition validity interference value after the validity adjustment and determines whether to perform an integrity adjustment, thereby achieving an improvement in the accuracy of medium license plate and vehicle identification and matching, and then achieving an improvement in data accuracy in the process of medium license plate and vehicle identification and matching, effectively solving the problem of low data accuracy in the process of medium license plate and vehicle identification and matching in the prior art.

[0085] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0086] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0087] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0088] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0089] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0090] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A highway vehicle and license plate recognition and analysis method based on radio frequency sensing, characterized in that: The following steps are involved: S1, based on the gantry license plate recognition flow information, obtain vehicle license plate recognition data to obtain a license plate recognition interference value, and determine whether to perform license plate validity interference evaluation based on the license plate recognition interference value, wherein the license plate recognition interference value is used to evaluate the interference status of the vehicle's license plate recognition at a preset time point; S2, obtaining a license plate recognition effectiveness interference value based on the signal propagation path length obtained from the gantry license plate recognition flow information and a license plate recognition interference value that is not higher than a preset license plate recognition interference value, and determining whether to perform effectiveness adjustment based on the license plate recognition effectiveness interference value, wherein the license plate recognition effectiveness interference value is used to evaluate the interference status of the license plate recognition effectiveness of the vehicle at a preset time point; S3, obtaining a license plate recognition integrity interference value based on the vehicle license plate recognition integrity data obtained from the gantry license plate recognition flow information and the license plate recognition validity interference value after validity adjustment, and judging whether to perform integrity adjustment based on the license plate recognition integrity interference value, wherein the license plate recognition integrity interference value is used to evaluate the interference status of the vehicle's license plate recognition integrity at a preset time point.

2. The highway vehicle and license plate recognition and analysis method based on radio frequency sensing as claimed in claim 1 is characterized in that: The vehicle plate recognition data includes the length of the license plate image, the width of the license plate image, the number of horizontal pixels, the number of vertical pixels, the exposure value, the horizontal pixel intensity and the vertical pixel intensity; The vehicle license plate recognition integrity data includes signal frequency and path distance.

3. The highway vehicle and license plate recognition and analysis method based on radio frequency sensing as claimed in claim 2 is characterized in that: The license plate recognition interference value is obtained by a horizontal pixel error value, a vertical pixel error value, a horizontal brightness error value and a vertical brightness error value; The horizontal pixel error value is represented by the result of a ratio operation between the initial horizontal pixel difference value and a preset horizontal pixel threshold value obtained from a database; The initial horizontal pixel difference is represented by the result of a difference operation between a preset horizontal pixel threshold and the ratio of the license plate image length and the number of horizontal pixels; The vertical pixel error value is represented by the result of a ratio operation between the initial vertical pixel difference value and a preset vertical pixel threshold value obtained from a database; The initial vertical pixel difference is represented by the result of a difference operation between a preset vertical pixel threshold and the ratio of the license plate image width and the number of vertical pixels; The horizontal brightness error value is represented by the result of a ratio operation between the initial horizontal brightness difference value and a preset horizontal brightness threshold value obtained from a database; The initial horizontal brightness difference is represented by the result of a difference operation between a preset horizontal brightness threshold and the initial horizontal brightness value; The initial horizontal brightness value is represented by the result of multiplying the exposure value by the average value of the horizontal pixel light intensity; The vertical brightness error value is represented by the result of a ratio operation between the initial vertical brightness difference value and a preset vertical brightness threshold value obtained from a database; The initial vertical brightness difference is represented by the result of performing a difference operation between a preset vertical brightness threshold and the initial vertical brightness value; The initial vertical brightness value is represented by the result of multiplying the exposure value by the average value of the vertical pixel light intensity.

4. The highway vehicle and license plate recognition and analysis method based on radio frequency sensing as claimed in claim 3 is characterized in that: The specific acquisition process of judging whether to perform license plate validity interference evaluation based on the license plate recognition interference value is as follows: Determine whether the license plate recognition interference value is not higher than the preset license plate recognition interference value: When the license plate recognition interference value is not higher than the preset license plate recognition interference value, the license plate validity interference evaluation is performed; When the license plate recognition interference value is higher than the preset license plate recognition interference value, a recognition error prompt is sent to the preset personnel.

5. The highway vehicle and license plate recognition and analysis method based on radio frequency sensing as claimed in claim 2 is characterized in that: The license plate recognition validity interference value is obtained by using a delay spread error value and a license plate recognition interference value that is not higher than a preset license plate recognition interference value; The delay spread error value is represented by the result of a ratio operation between the initial delay spread difference value and a preset delay spread threshold value obtained from a database; The initial delay spread difference is represented by the result of a difference operation between the ratio of the signal propagation path length and the speed of light obtained from the database and a preset delay spread threshold.

6. The highway vehicle and license plate recognition and analysis method based on radio frequency sensing as claimed in claim 5 is characterized in that: The specific process of determining whether to perform effectiveness adjustment is as follows: Step 1, judging whether the license plate recognition validity interference value meets the validity condition, if so, no validity adjustment is performed, otherwise, step 2 is executed, the validity condition indicates that the license plate recognition validity interference value is not higher than the preset recognition validity interference threshold obtained from the database; Step 2: Optimize spectrum resources. When the monitored effective interference value meets the effectiveness condition, stop effective interference. Otherwise, execute step 3. Step three, make up for the lighting impact. When the monitored validity interference value meets the validity condition, stop the validity interference. Otherwise, send an identification error prompt to the preset person.

7. The highway vehicle and license plate recognition and analysis method based on radio frequency sensing as claimed in claim 2 is characterized in that: The license plate recognition integrity interference value is obtained by using the distance loss error value, the signal frequency loss error value and the license plate recognition effectiveness interference value after effectiveness adjustment; The distance loss error value is represented by the result of a ratio calculation between the initial distance loss difference value and a preset path loss threshold value obtained from a database; The initial distance loss difference is represented by the result of performing a logarithmic operation on the path distance and performing a difference operation on the preset path loss threshold; The signal frequency loss error value is represented by the result of a ratio operation between the initial frequency loss difference value and a preset signal frequency loss threshold value obtained from a database; The initial frequency loss difference is represented by the result of performing a logarithmic operation on the signal frequency and performing a difference operation on the preset signal frequency loss threshold.

8. The highway vehicle and license plate recognition and analysis method based on radio frequency sensing as claimed in claim 7 is characterized in that: The specific process of judging whether to perform integrity adjustment based on the license plate recognition integrity interference value is as follows: The first step is to determine whether the license plate recognition integrity interference value meets the integrity condition. If so, no integrity adjustment is performed. Otherwise, the second step is performed. The integrity condition indicates that the license plate recognition integrity interference value is not higher than a preset recognition integrity threshold obtained from the database. The second step is to perform signal enhancement. When the monitored license plate recognition integrity interference value meets the integrity condition, the integrity interference is stopped, otherwise the third step is executed; The third step is to attenuate the low-frequency components. When the monitored license plate recognition integrity interference value meets the integrity condition, the integrity interference is stopped. Otherwise, a recognition error prompt is sent to the preset personnel.

9. The highway vehicle and license plate recognition and analysis method based on radio frequency sensing as claimed in claim 3, characterized in that: The restriction expression of the license plate recognition interference value is as follows: Where, TS w represents the license plate recognition interference value of the license plate at the wth preset time point, w=1,2,...,a, w represents the number of the preset time point, a represents the total number of preset time points, SP w represents the horizontal pixel error value of the license plate at the wth preset time point, CP w Indicates the vertical pixel error value of the license plate at the wth preset time point, IX w Indicates the horizontal brightness error value of the license plate at the wth preset time point, IY w Indicates the vertical brightness error value of the license plate at the wth preset time point, LX w represents the length of the license plate image at the wth preset time point, LY w Indicates the width of the license plate image at the wth preset time point, NX w Indicates the number of horizontal pixels of the license plate at the wth preset time point, NY w represents the number of vertical pixels of the license plate at the wth preset time point, E w represents the exposure value of the license plate at the wth preset time point, X mw represents the horizontal pixel intensity of the mth pixel in the horizontal direction of the license plate image at the wth preset time point, m = 1, 2, ..., b, m represents the number of the horizontal pixel in the license plate image, b represents the total number of horizontal pixels in the license plate image, Y nw represents the vertical pixel light intensity of the nth pixel in the vertical direction of the license plate image at the wth preset time point, n=1,2,...,k, n represents the number of the vertical pixel in the license plate image, k represents the total number of vertical pixel in the license plate image, SP0 represents the preset horizontal pixel threshold, CP0 represents the preset vertical pixel threshold, IX0 represents the preset horizontal brightness threshold, IY0 represents the preset vertical brightness threshold, e represents the natural constant, ΔSP represents the reference horizontal pixel range, ΔCP represents the reference vertical pixel range, ΔIX represents the reference horizontal brightness range, and ΔIY represents the reference vertical brightness range.

10. The highway vehicle and license plate recognition and analysis method based on radio frequency sensing as claimed in claim 2, characterized in that: The path distance represents the distance between the license plate and the gantry during the gantry recognition process; The signal propagation path length represents the maximum path length of the signal propagation during the gantry recognition of the license plate; The horizontal pixel number represents the number of pixels in the horizontal direction of the license plate image during the gantry recognition process; The vertical pixel number represents the number of pixels in the vertical direction of the license plate image during the gantry recognition process.

Images