Rapid and accurate NOx detection system for non-road mobile machinery

Abstract

The invention discloses a rapid and accurate NOx detection system for non-road mobile machinery, and belongs to the technical field of non-road mobile machinery emission detection.The rapid and accurate NOx detection system comprises a tail gas sampling module used for collecting tail gas emission data of the non-road mobile machinery, and the tail gas emission data comprises the concentration of nitric oxide; the data processing module responds to the tail gas sampling module and is used for preprocessing the collected tail gas emission data, including data cleaning and data correction; the data cleaning comprises abnormal value removal, and the data correction comprises temperature correction; and the data distinguishing module is used for distinguishing the collected tail gas emission data. According to the method, the temperature compensation model is established, the nitrogen oxide concentration in the tail gas emission data is corrected, and the influence of temperature change on the detection result is eliminated, so that the accuracy of the detection data is improved, and the environmental adaptability and the intelligent level of the system are enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of non-road mobile machinery emission detection, in particular to a rapid and accurate NOx detection system for non-road mobile machinery. BACKGROUND

[0002] Non-road mobile machinery is widely used in engineering construction, agriculture, ports and airports, etc. The nitrogen oxides (NOx) emitted by its engine is an important source of air pollution, and its emission is directly discharged into the low air, which has a greater impact on the environment. Therefore, it is necessary to detect its emissions.

[0003] For this research, the application number CN202010463826.7 provides a portable non-road mobile machinery particulate matter emission rapid detection device. The technical solution includes an opaque smoke meter, a vehicle-mounted terminal module, a control unit and an intelligent terminal. The opaque smoke meter is connected to the control unit for obtaining the opaque smoke value in the exhaust gas and transmitting the data to the control unit. The vehicle-mounted terminal module is connected to the control unit for obtaining the engine power, oil consumption, air intake mass flow and transmitting the data to the control unit. This technical solution can independently calculate the particulate matter emission ratio by opaque smoke value, engine power, oil consumption and air intake mass flow of non-road vehicles.

[0004] Another application number CN202410588317.5 provides a remote monitoring non-road mobile machinery NOx emission calculation method. This technical solution adopts a method of dividing the power base window from front to back by seconds, and effectively utilizes the NOx emission data of the machinery under all effective working events by long-time calculation and analysis of the pollutant NOx emission of the machinery under various working conditions. It evaluates the NOx emission ratio under all windows, avoids the emission result controversy caused by differences in test conditions, test methods or data processing methods, and effectively feedbacks the actual NOx emission level of the machinery.

[0005] However, the above technical solutions mainly rely on laboratory tests or portable emission measurement systems (PEMS), but the former has long test cycle and high cost, and the latter has complex equipment and limited application. At the same time, the existing detection system has deficiencies in data processing, which cannot correct and compensate the detection results in real time, and it is difficult to eliminate the influence of environmental factors (such as temperature) on the detection results. Therefore, a system capable of rapidly and accurately detecting non-road mobile machinery NOx emission on site is needed. SUMMARY

[0006] In view of the above problems existing in the prior art of non-road mobile machinery emission detection, the present application is proposed.

[0007] Therefore, one of the purposes of the present application is to provide a rapid and accurate NOx detection system for non-road mobile machinery, which corrects the concentration of nitrogen oxides in the exhaust emission data by establishing a temperature compensation model, eliminates the influence of temperature changes on the detection results, thereby improving the accuracy of the detection data and enhancing the environmental adaptability and intelligent level of the system.

[0008] To solve the above technical problems, the present application provides the following technical solutions:

[0009] The present application provides a rapid and accurate NOx detection system for non-road mobile machinery, comprising:

[0010] An exhaust sampling module for collecting exhaust emission data of non-road mobile machinery, the exhaust emission data including the concentration of nitrogen oxides;

[0011] A data processing module responsive to the exhaust sampling module for preprocessing the collected exhaust emission data, including data cleaning and data correction; the data cleaning includes removing outliers, and the data correction includes temperature correction;

[0012] A data differentiation module for differentiating the collected exhaust emission data, the differentiation including differentiating based on different driving speeds of the non-road mobile machinery and analyzing the regular changes of the exhaust emission data corresponding to different driving speeds;

[0013] A data fusion processing module for fusion processing of the analyzed regular changes; the data fusion processing module includes a calculation unit, a statistical unit, an analysis unit and a data determination unit;

[0014] The calculation unit is responsive to the regular changes for calculating the data difference of the exhaust emission data between different driving speeds;

[0015] The statistical unit is used to statistically analyze the maximum 3-5 exhaust emission data collected at the same driving speed of the non-road mobile machinery according to the regular changes, and generate a data set, while marking each exhaust emission data in the data set as reference data;

[0016] The analysis unit is responsive to the data set for analyzing the correlation between the formation of each exhaust emission data in the data set and environmental factors, including environmental temperature;

[0017] The data determination unit is used to determine the accuracy of the exhaust emission data collected in the future period, and when the exhaust emission data collected in the future period at the same driving speed and under the same environmental factors is different from the reference data, the system determines that the collected exhaust emission data is abnormal; otherwise, it is not determined.

[0018] As a preferred scheme of the present application, wherein: in the data processing module, further comprising feature extraction and analysis of the exhaust emission data, the feature extraction and analysis includes key feature extraction, correlation analysis and trend analysis;

[0019] The key feature extraction is to extract features related to exhaust emission from the collected exhaust emission data, and the related features include particulate matter concentration, carbon monoxide concentration and nitrogen oxide concentration;

[0020] In the key feature extraction, further comprising extracting derived features, the derived features include the emission rate, total emission and emission rate per unit time of the non-road mobile machinery;

[0021] The correlation analysis is to analyze the correlation between the exhaust emission data and different features, including the relationship between the concentration of nitrogen oxides and the engine load and speed of the non-road mobile machinery, or the relationship between the particulate matter concentration and the exhaust temperature;

[0022] The trend analysis is to obtain the change trend of the exhaust emission data through time series analysis.

[0023] As a preferred scheme of the present application, wherein: in the data processing module, the temperature correction includes correcting the exhaust emission data by establishing a temperature compensation model to eliminate the influence of temperature change on the concentration of nitrogen oxides, and the correction steps include:

[0024] According to the collected exhaust emission data, determine the parameters of the temperature compensation model;

[0025] Substitute the concentration of nitrogen oxides in the collected exhaust emission data and the corresponding environmental factors into the temperature compensation model to calculate the corrected concentration of nitrogen oxides;

[0026] Compare the concentration of nitrogen oxides before and after correction to verify the correction result;

[0027] According to the correction result, adjust the parameters of the temperature compensation model to improve the accuracy of correction;

[0028] Regularly update the temperature compensation model with newly collected exhaust emission data;

[0029] Record the corrected concentration of nitrogen oxides and generate an emission report on the non-road mobile machinery.

[0030] As a preferred scheme of the present application, wherein: in the data processing module, the data correction further includes background correction, and the steps of the background correction include:

[0031] selecting a region with low traffic flow as a background region, detecting the concentration of nitrogen oxides in the background region, and deducting the detected concentration of nitrogen oxides from the collected exhaust emission data;

[0032] fitting and correcting the background value by a time series analysis method; the time series analysis method includes a thin plate spline regression smoothing method;

[0033] The data correction also includes chemical correction.

[0034] The chemical correction includes removing interfering gases in the exhaust emission data to improve the accuracy of the detection of the concentration of nitrogen oxides; the interfering gases include sulfur dioxide and carbon monoxide.

[0035] A chemical compensation model is established to correct the detected concentration of nitrogen oxides.

[0036] As a preferred scheme of the present application, wherein: the concentration of nitrogen oxides in the collected exhaust emission data and the corresponding environmental factors are substituted into the temperature compensation model to calculate the corrected concentration of nitrogen oxides, and the linear regression model is used to calculate as follows:

[0037] wherein, represents the corrected concentration of nitrogen oxides, i.e. NOx concentration;

[0038] In the formula, represents the original NOx concentration, T represents the actual environmental temperature, T0 represents the reference temperature, and a is the linear regression coefficient, representing the change in NOx concentration when the environmental temperature changes by 1℃.

[0039] As a preferred scheme of the present application, wherein: the following formula is also used to calculate:

[0040]

[0041] In the formula, H represents the actual environmental humidity, H0 represents the reference humidity, P represents the actual environmental pressure, P0 represents the reference pressure, and a1, a2, and a3 are multiple regression coefficients.

[0042] As a preferred scheme of the present application, wherein: the different driving speeds of the non-road mobile machinery are divided into wherein, The emission rate of the non-road mobile machinery at different driving speeds is collected, a database about the emission rate at different driving speeds is constructed, and the data corresponding to the emission rate in each database is at least 10, the minimum emission rate is obtained from the data, and when the tail gas emission data of the non-road mobile machinery is collected in the future period, if the collected emission rate is lower than the minimum emission rate under the same driving speed, the system determines that the detection is abnormal; otherwise, it is not determined.

[0043] As a preferred scheme of the present application, wherein: the change characteristics of the data in each database are analyzed, the difference of the emission rate of the non-road mobile machinery under each driving speed is obtained, the difference is marked as a reference difference, and when the tail gas emission data of the non-road mobile machinery is collected in the future period, if the obtained difference of the emission rate is higher than the reference difference under the same driving speed, the system determines that the tail gas emission data of the non-road mobile machinery is over-standard; otherwise, it is not determined.

[0044] As a preferred scheme of the present application, wherein: if the system determines that the tail gas emission data of the non-road mobile machinery is over-standard, the first to third emission rates corresponding to the over-standard tail gas emission data are obtained, the emission rates are marked as risk emission rates, and when the tail gas emission data of the non-road mobile machinery is collected in the future period, if the obtained emission rate is the same as or higher than the risk emission rate under the same driving speed, the system determines that the tail gas emission data of the non-road mobile machinery is over-standard; otherwise, it is not determined.

[0045] Beneficial effects:

[0046] 1. By establishing a temperature compensation model, the concentration of nitrogen oxides (NO x ) in the tail gas emission data is corrected, the influence of temperature change on the detection result is eliminated, and the accuracy of the detection data is improved; in addition to temperature correction, various correction methods such as background correction and chemical correction are combined to further improve the reliability of the detection data;

[0047] 2. According to the different driving speeds of the non-road mobile machinery, the tail gas emission data is distinguished and analyzed, which can more accurately reflect the emission law under different working conditions; and by analyzing the change law of the tail gas emission data, a reference data set is generated, which provides a reliable benchmark for subsequent emission detection;

[0048] 3. By optimizing the detection process and algorithm, the rapid processing and analysis of the tail gas emission data are realized, the detection efficiency is improved, and the risk emission rate is marked by analyzing the change characteristics of the emission rate, which provides a basis for the operation optimization and fault warning of the equipment. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0050] Fig. 1 This is a schematic diagram of the modular structure of a rapid and accurate NOx detection system for non-road mobile machinery according to an embodiment of the present invention;

[0051] Fig. 2 This is a schematic diagram of the process structure of an embodiment of the present invention;

[0052] The diagram is labeled as follows: 110 - Exhaust gas sampling module; 120 - Data processing module; 130 - Data differentiation module; 140 - Data fusion processing module; 1401 - Calculation unit; 1402 - Statistical unit; 1403 - Analysis unit; 1404 - Data judgment unit. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0054] Existing technologies mainly rely on laboratory testing or vehicle emission monitoring systems (PEMS). However, the former has a long testing cycle and high cost, while the latter has complex equipment and limited applications. At the same time, existing detection systems have shortcomings in data processing, cannot perform real-time correction and compensation of test results, and are unable to eliminate the influence of environmental factors (such as temperature) on test results.

[0055] Based on this, the present invention proposes a rapid and accurate NOx detection system for non-road mobile machinery. By establishing a temperature compensation model, the system corrects the nitrogen oxide concentration in exhaust emission data, eliminates the influence of temperature changes on the detection results, thereby improving the accuracy of the detection data and enhancing the system's environmental adaptability and intelligence level.

[0056] The present solution will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0057] Reference Figs. 1-2For an embodiment of the present application, the embodiment provides a rapid and accurate NOx detection system for off-road mobile machinery, comprising:

[0058] An exhaust sampling module 110 is configured to collect exhaust emission data of the off-road mobile machinery, the exhaust emission data including concentration of nitrogen oxides;

[0059] In the embodiment, the exhaust sampling module includes a sampling probe, which is installed at an exhaust emission port of the off-road mobile machinery to obtain an exhaust sample, and a filtering device can be arranged inside the sampling probe to filter particulate matters in the exhaust to prevent the detection channel from being blocked;

[0060] A data processing module 120 is configured to respond to the exhaust sampling module and to preprocess the collected exhaust emission data, including data cleaning and data correction; the data cleaning includes removing outliers, and the data correction includes temperature correction;

[0061] In the embodiment, for removing outliers, abnormal data can be generated due to instrument failure, environmental interference or operation error during the exhaust detection process, and these outliers can be identified and removed by setting a reasonable threshold (such as upper and lower limits of NO x concentration);

[0062] For temperature correction, the exhaust temperature can affect the accuracy of the detection results, and a temperature compensation model can be established to correct the detection data to eliminate the influence of temperature variation on NO x concentration and improve data quality;

[0063] A data classification module 130 is configured to classify the collected exhaust emission data, and the classification manner includes classifying based on different driving speeds of the off-road mobile machinery to analyze regular changes of the exhaust emission data corresponding to different driving speeds; the exhaust emission regularity of the off-road mobile machinery under different driving states can be more comprehensively mastered to provide a basis for formulating targeted emission reduction measures;

[0064] In the embodiment, the data classification module classifies the exhaust emission data according to different driving speeds to more carefully understand the emission characteristics under different working conditions;

[0065] A data fusion processing module 140 is configured to fuse and process the analyzed regular changes; the data fusion processing module 140 includes a calculation unit 1401, a statistical unit 1402, an analysis unit 1403 and a data determination unit 1404;

[0066] The calculation unit 1401 is configured to calculate data differences of the exhaust emission data between different driving speeds in response to the regular changes;

[0067] The statistical unit 1402 is configured to statistically collect 3-5 maximum exhaust emission data of the non-road mobile machinery at the same driving speed according to regular changes, and generate a data set, and mark each exhaust emission data in the data set as reference data;

[0068] The analysis unit 1403 is configured to analyze the correlation between the formation of each exhaust emission data in the data set and environmental factors, including environmental temperature, in response to the data set;

[0069] The data determination unit 1404 is configured to determine the accuracy of the exhaust emission data collected in the future period. When the exhaust emission data collected in the future period at the same driving speed and under the same environmental factors is different from the reference data, the system determines that the collected exhaust emission data is abnormal; otherwise, it is not determined,

[0070] In the data processing module, it also includes feature extraction and analysis of the exhaust emission data, which includes key feature extraction, correlation analysis and trend analysis;

[0071] The key feature extraction is to extract the features related to the exhaust emission from the collected exhaust emission data, including particulate matter concentration, carbon monoxide concentration and nitrogen oxide concentration;

[0072] In the key feature extraction, it also includes extracting derived features, including the emission rate of the non-road mobile machinery, the total emission amount and the emission change rate per unit time;

[0073] The correlation analysis is to analyze the correlation between the exhaust emission data and different features, including the relationship between the nitrogen oxide concentration and the engine load and speed of the non-road mobile machinery, or the relationship between the particulate matter concentration and the exhaust temperature;

[0074] In this embodiment, it helps to understand the internal law of exhaust emission and provides a basis for optimizing emission control;

[0075] The trend analysis is to obtain the change trend of the exhaust emission data through time series analysis;

[0076] In this embodiment, the change trend of the exhaust emission data is studied to determine whether the emission is increasing or decreasing, and whether there is a periodic change;

[0077] In the data processing module, the temperature correction includes correcting the exhaust emission data by establishing a temperature compensation model to eliminate the influence of temperature change on the concentration of nitrogen oxides, and the steps of correction include:

[0078] According to the collected exhaust emission data, the parameters of the temperature compensation model are determined;

[0079] In this embodiment, for example, for a linear regression model, the slope and intercept need to be determined;

[0080] The concentration of nitrogen oxides in the collected exhaust emission data and the corresponding environmental factors are substituted into the temperature compensation model to calculate the corrected concentration of nitrogen oxides;

[0081] Compare the concentrations of nitrogen oxides before and after correction to verify the correction results;

[0082] According to the correction results, adjust the parameters of the temperature compensation model to improve the accuracy of the correction;

[0083] Periodically update the temperature compensation model with newly collected exhaust emission data;

[0084] In this embodiment, a new rule is established to adapt to temperature changes;

[0085] Record the corrected concentration of nitrogen oxides and generate an emission report for non-road mobile machinery;

[0086] In this embodiment, it is convenient for subsequent analysis and reporting to provide a basis for environmental protection and equipment optimization;

[0087] By establishing a temperature compensation model to correct exhaust emission data, the influence of temperature changes on the concentration of nitrogen oxides can be effectively eliminated;

[0088] The correction process includes parameter determination, correction result verification, model parameter adjustment, and periodic updating, ensuring continuous optimization and adaptability of the model;

[0089] In the data processing module, data correction also includes background correction, the steps of which include:

[0090] Select an area with low traffic flow as the background area, detect the concentration of nitrogen oxides in the background area, and subtract the detected concentration of nitrogen oxides from the collected exhaust emission data;

[0091] Fit and correct the background value by time series analysis method; the time series analysis method includes thin plate spline regression smoothing method;

[0092] Data correction also includes chemical correction;

[0093] Chemical correction includes removing interfering gases in exhaust emission data to improve the accuracy of detecting the concentration of nitrogen oxides; interfering gases include sulfur dioxide and carbon monoxide;

[0094] Establish a chemical compensation model to correct the detected concentration of nitrogen oxides;

[0095] In this embodiment, the thin plate spline (TPS) regression smoothing method is a non-parametric regression method for data smoothing, which fits data points by minimizing the energy of thin plate bending, and is suitable for processing non-linear functions with multiple extreme points;

[0096] The background correction can effectively remove the background interference by selecting a background region to detect the background concentration and deducting, and using a time series analysis method to fit and correct the background value;

[0097] The chemical correction further improves the accuracy of the detection of nitrogen oxide concentration by removing interfering gases and establishing a chemical compensation model, so that the detection result can more truly reflect the exhaust emission condition of non-road mobile machinery;

[0098] Further, the concentration of nitrogen oxides in the collected exhaust emission data and the corresponding environmental factors are substituted into the temperature compensation model to calculate the corrected concentration of nitrogen oxides, and the linear regression model is used to calculate the corrected concentration of nitrogen oxides, as follows:

[0099] wherein, represents the corrected concentration of nitrogen oxides, i.e. NOx concentration;

[0100] In the formula, represents the original NOx concentration, T represents the actual environmental temperature, T0 represents the reference temperature, and a is the linear regression coefficient, which represents the change amount of NOx concentration when the environmental temperature changes by 1℃;

[0101] In this embodiment, the reference temperature is usually a standard temperature, such as 25℃;

[0102] The corrected concentration of nitrogen oxides can be quickly obtained, which improves the real-time performance and response speed of the detection system;

[0103] On the basis of the above, the following formula is used to calculate:

[0104]

[0105] In the formula, H represents the actual environmental humidity, H0 represents the reference humidity, P represents the actual environmental pressure, P0 represents the reference pressure, and a1, a2, a3 are multivariate regression coefficients;

[0106] In this embodiment, the coefficients (such as a, a1, a2) in the formula need to be fitted and determined through experimental data or historical data, and in actual application, appropriate models and formulas need to be selected according to specific conditions, and necessary tests need to be performed;

[0107] Further, the embodiment considers the actual ambient humidity, the reference humidity, the actual ambient pressure, the reference pressure and other factors, and can more comprehensively consider the influence of various environmental factors on the concentration of nitrogen oxides.

[0108] Further, the embodiment divides the different driving speeds of the non-road mobile machinery into Among them, The n-th driving speed is divided, the emission rate of the non-road mobile machinery at different driving speeds is collected, a database about the emission rate at different driving speeds is constructed, and the data corresponding to the emission rate in each database is at least 10. The minimum emission rate is obtained in the data. When collecting the exhaust emission data of the non-road mobile machinery in the future period, if the collected emission rate is lower than the minimum emission rate under the same driving speed, the system determines that the detection is abnormal; otherwise, it is not determined.

[0109] In the embodiment, the different driving speeds of the non-road mobile machinery are divided into multiple levels, and the database is constructed according to the collected emission rate at different driving speeds, so that the emission characteristics under different driving speeds can be more detailedly understood.

[0110] And by obtaining the minimum emission rate as a reference, the emission can be quickly judged to be abnormal in future detection.

[0111] On the basis of the above, the change characteristics of the data in each database are analyzed, the difference of the emission rate of the non-road mobile machinery under each driving speed is obtained, and the difference is marked as a reference difference. When collecting the exhaust emission data of the non-road mobile machinery in the future period, if the difference of the obtained emission rate is higher than the reference difference under the same driving speed, the system determines that the exhaust emission data of the non-road mobile machinery is over standard; otherwise, it is not determined.

[0112] In the embodiment, by analyzing the difference of the emission rate under each driving speed and marking it as a reference difference, it can be quickly judged whether the emission is over standard in future detection.

[0113] And the difference-based determination method is simple and intuitive, easy to implement, and can effectively reflect the change trend of the emission.

[0114] Further, if the system determines that the tail gas emission data of the non-road mobile machinery exceeds the standard, the first to third emission rates corresponding to the tail gas emission data exceeding the standard are obtained, and the emission rates are marked as risk emission rates. When collecting the tail gas emission data of the non-road mobile machinery in the future period, if the obtained emission rate is the same as or higher than the risk emission rate under the same driving speed, the system determines that the tail gas emission data of the non-road mobile machinery exceeds the standard; otherwise, it is not determined.

[0115] In the embodiment, when the system determines that the tail gas emission data exceeds the standard, the corresponding risk emission rate is obtained, and the same or higher rate than the risk emission rate is determined in the future detection, which can effectively prevent the reoccurrence of excessive emission.

[0116] The determination method based on the risk emission rate is prospective and preventive, which is helpful to find potential emission problems in advance.

[0117] In summary, the application corrects the concentration of nitrogen oxides in the tail gas emission data by establishing a temperature compensation model, eliminates the influence of temperature change on the detection result, improves the accuracy of the detection data, and enhances the environmental adaptability and intelligent level of the system.

[0118] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A fast and accurate NOx detection system for off-highway mobile machines, characterized in that, The application relates to a non-road mobile machinery exhaust emission data processing system, which comprises the following parts: an exhaust sampling module for collecting exhaust emission data of non-road mobile machinery, wherein the exhaust emission data comprises the concentration of nitrogen oxides; a data processing module, which is used for pre-processing the collected exhaust emission data, including data cleaning and data correction, and is responsive to the exhaust sampling module; the data cleaning comprises removing abnormal values, and the data correction comprises temperature correction; a data classification module, which is used for classifying the collected exhaust emission data, and the classification mode comprises classifying based on different driving speeds of the non-road mobile machinery and analyzing the regular variation of the exhaust emission data corresponding to different driving speeds; a data fusion processing module, which is used for fusion processing of the analyzed regular variation, and comprises a calculation unit, a statistical unit, an analysis unit and a data judgment unit; the calculation unit is used for calculating the data difference of the exhaust emission data between different driving speeds in response to the regular variation; the statistical unit is used for statistically analyzing the maximum 3-5 exhaust emission data of the non-road mobile machinery collected at the same driving speed according to the regular variation, and generating a data set, and meanwhile marking each exhaust emission data in the data set as reference data; the analysis unit is used for analyzing the correlation rule between the formation of each exhaust emission data in the data set and environmental factors, including environmental temperature, in response to the data set; the data judgment unit is used for judging the accuracy of the exhaust emission data collected in a future period, and when the exhaust emission data collected in the future period at the same driving speed and under the same environmental factors is different from the reference data, the system judges that the collected exhaust emission data is abnormal; otherwise, no judgment is made.

2. A quick and accurate NOx detection system for off-highway mobile machines as set forth in claim 1, wherein, In the data processing module, feature extraction and analysis of the exhaust emission data are further included, and the feature extraction and analysis comprises key feature extraction, correlation analysis and trend analysis; the key feature extraction is to extract features related to exhaust emission from the collected exhaust emission data, and the related features comprise the concentration of particulate matter, the concentration of carbon monoxide and the concentration of nitrogen oxides; in the key feature extraction, derivative features are further extracted, and the derivative features comprise the emission rate, total emission amount and emission change rate per unit time of the non-road mobile machinery; the correlation analysis is to analyze the correlation between the exhaust emission data and different features, including the relationship between the concentration of nitrogen oxides and the engine load and rotating speed of the non-road mobile machinery, or the relationship between the concentration of particulate matter and exhaust temperature; the trend analysis is to obtain the variation trend of the exhaust emission data through time series analysis.

3. A quick and accurate NOx detection system for off-highway mobile machines as defined in claim 1, wherein, In the data processing module, the temperature correction comprises correcting the exhaust emission data through a temperature compensation model to eliminate the influence of temperature variation on the concentration of nitrogen oxides, and the steps of the correction comprise: determining the parameters of the temperature compensation model according to the collected exhaust emission data; The concentration of nitrogen oxides in the collected exhaust emission data and the corresponding environmental factors are substituted into the temperature compensation model to calculate the corrected concentration of nitrogen oxides. The concentrations of nitrogen oxides before and after correction are compared to verify the correction results. According to the correction results, the parameters of the temperature compensation model are adjusted to improve the accuracy of correction. The temperature compensation model is periodically updated with newly collected exhaust emission data. The corrected concentration of nitrogen oxides is recorded, and an emission report on non-road mobile machinery is generated.

4. A quick and accurate NOx detection system for off-highway mobile machines as defined in claim 1, wherein, In the data processing module, the data correction also includes background correction, the steps of which include: Select an area with low traffic flow as the background area, detect the concentration of nitrogen oxides in the background area, and subtract the detected concentration of nitrogen oxides from the collected exhaust emission data; The background value is fitted and corrected by a time series analysis method, which includes a thin plate spline regression smoothing method; The data correction also includes chemical correction; The chemical correction includes removing interfering gases in the exhaust emission data to improve the accuracy of detecting the concentration of nitrogen oxides; the interfering gases include sulfur dioxide and carbon monoxide; A chemical compensation model is established to correct the detected concentration of nitrogen oxides.

5. A quick and accurate NOx detection system for off-highway mobile machines as set forth in claim 3, characterized in that, The concentration of nitrogen oxides in the collected exhaust emission data and the corresponding environmental factors are substituted into the temperature compensation model to calculate the corrected concentration of nitrogen oxides, which is calculated according to a linear regression model, as follows: wherein, denotes the concentration of the corrected nitrogen oxides, i.e. the NOx concentration; In the formula, wherein NOx0represents the original NOx concentration, T represents the actual ambient temperature, TO represents the reference temperature, and a is a linear regression coefficient representing the amount of change in NOx concentration per 1 °C change in ambient temperature.

6. A quick and accurate NOx detection system for off-highway mobile machines as set forth in claim 5, characterized in that, It also includes calculation by the following formula: In the formula, H represents the actual environmental humidity, H0 represents the reference humidity, P represents the actual environmental pressure, P0 represents the reference pressure, a1, a2, and a3 are multiple regression coefficients.

7. A quick and accurate NOx detection system for off-highway mobile machines as defined in claim 2, wherein, distinguishing different driving speeds of the non-road mobile machine wherein, indicates the n-th driving speed, the emission rate of the non-road mobile machine at different driving speeds is collected, a database about the emission rate at different driving speeds is constructed, and the data corresponding to the emission rate in each database is at least 10, the minimum emission rate is obtained from the data, and when the exhaust emission data of the non-road mobile machine is collected in the future period, if the collected emission rate is lower than the minimum emission rate under the same driving speed, the system determines that the detection is abnormal; otherwise, it is not determined.

8. A quick and accurate NOx detection system for off-highway mobile machines as set forth in claim 7, characterized in that, In each database, analyze the variation characteristics of the data to obtain the difference in emission rate of the non-road mobile machinery under each driving speed condition, and mark the difference as a reference difference. When collecting exhaust emission data of the non-road mobile machinery in the future period, under the same driving speed condition, if the obtained difference in emission rate is higher than the reference difference, the system determines that the exhaust emission data of the non-road mobile machinery is over-standard; otherwise, it is not determined.

9. A quick and accurate NOx detection system for off-highway mobile machines as set forth in claim 8, characterized in that, If the system determines that the exhaust emission data of the non-road mobile machinery is over-standard, the first to third emission rates corresponding to the over-standard exhaust emission data are obtained, and the emission rates are marked as risk emission rates. When collecting exhaust emission data of the non-road mobile machinery in the future period, under the same driving speed condition, if the obtained emission rate is the same as or higher than the risk emission rate, the system determines that the exhaust emission data of the non-road mobile machinery is over-standard; otherwise, it is not determined.

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