Track validity verification method for ADS-b monitoring application system

Abstract

A track validity verification method for an ADS-B monitoring application system, specifically comprising introducing an outlier detection mechanism to eliminate the impact of outliers on subsequent processing. The weighted average speed is used to replace other speed calculation methods. The M / N criterion is optimized for deficiencies of the M / N criterion. Some processing steps in horizontal position verification, horizontal speed verification and vertical position verification can be reused, thereby further saving resources and improving verification efficiency.

Description

A track validity verification method for ADS-B monitoring application system TECHNICAL FIELD

[0001] The present application relates to the field of air traffic surveillance, and in particular to a track validity verification method for ADS-B monitoring application system. BACKGROUND

[0002] Automatic Dependent Surveillance-Broadcast, ADS-B, is an advanced air surveillance technology, which realizes real-time monitoring of aircraft tracks by broadcasting the position, speed and other information of the aircraft. ADS-B monitoring application system is established on the basis of ADS-B IN reception, and outputs ADS-B tracks meeting data quality requirements through monitoring and application processing of ADS-B received tracks.

[0003] However, there are still quite a number of early ADS-B devices using relatively early standards, such as DO260 and DO260A, and such devices have the problem of lacking relevant data quality parameters or the quality parameters being unable to reflect the actual data precision. In addition, the ADS-B data quality transmitted by the existing ADS-B device DO-260B also cannot meet the processing standards of the ADS-B monitoring application system. Therefore, in order to ensure that the existing ADS-B monitoring application system can receive enough tracks meeting the data quality requirements, a verification method for track data validity is needed.

[0004] The existing track validity verification method includes a non-smooth track verification method, which directly determines the validity of the horizontal position, horizontal speed and vertical speed data of adjacent tracks. However, this method is not suitable for cases where speed data is missing or the speed data quality is poor, and through analysis of track data, in the case of small time intervals, the position information of the adjacent two tracks will have a large error. To solve this problem, an alternative method of smooth track horizontal position verification is proposed in the prior art. By increasing the length of the time window used in the calculation, the influence of the time error in the position update can be reduced.

[0005] In addition, in view of the problem that ADS-B devices cannot provide effective speed quality indicators, the prior art also discloses a method of verifying speed validity based on position information. This method is suitable for use during aircraft cruising, and its main idea is to calculate the horizontal speed of the aircraft within 2s-10s before and after the current track, and compare the difference between the calculated speed and the speed in the track with the threshold 7m / s2, and make a consistency judgment of the data through M / N criterion, that is, M tracks in N tracks have a speed difference less than the threshold.

[0006] By analyzing the effectiveness verification method proposed by the prior art, the shortcomings of the existing method are summarized:

[0007] Main disadvantage one: the existing technology proposed by the track verification method without smoothing is not suitable for the case of missing speed data or poor quality of speed data.

[0008] Main disadvantage two: the accuracy of the method of the prior art cannot be guaranteed in the case of small time interval.

[0009] Main disadvantage three: the horizontal position verification method proposed in the prior art is based on the idea of sliding window, which requires calculation of speed, position and time interval spanning multiple time points for each time point, resulting in significant increase in calculation amount. In addition, if there is an abnormal value at a certain time, it will affect the calculation of acceleration at multiple time points, which may cause the track that meets the quality requirements to be mistakenly filtered out.

[0010] Main disadvantage four: the speed verification method based on position change proposed by the prior art has a large amount of calculation, and the speed calculation has a delay of 2s-10s. At the same time, different speed calculation methods are used in position verification and speed verification, resulting in significant increase in calculation amount and resource waste.

[0011] Main disadvantage five: although the M / N criterion can resist the influence of single abnormal value, continuous abnormal values may affect the accuracy of the final judgment, and the M and N values are generally fixed, which cannot adapt to dynamic environment. SUMMARY

[0012] Therefore, the present application provides a track validity verification method for ADS-B monitoring application system, which solves the problems in the prior art and improves the accuracy of track validity verification.

[0013] The track validity verification method for ADS-B monitoring application system provided by the present application adopts the following technical scheme:

[0014] A track validity verification method for ADS-B monitoring application system, comprising:

[0015] Step 1, pre-processing of track data:

[0016] Calculate the difference between the horizontal positions of the last track and the current track as the first difference;

[0017] Calculate the difference between the vertical positions of the adjacent two tracks as the second difference;

[0018] Calculate the difference between the horizontal speeds of the adjacent two tracks as the third difference;

[0019] Calculate the difference between the applicable times of the adjacent two tracks as the fourth difference;

[0020] Step 2, performing outlier detection on the track, if the first difference value of the track is within a preset range, then performing Step 3, otherwise, the track position validity verification fails;

[0021] Step 3, calculating the horizontal weighted average speed and the vertical weighted average speed of the track based on the weighted sliding window method;

[0022] Step 4, calculating the horizontal estimated acceleration of each track according to the horizontal weighted average speed calculated in Step 3;

[0023] Step 5, comparing the vertical weighted speed calculated in Step 3 with a first threshold to determine the vertical position verification result, and comparing the horizontal estimated acceleration calculated in Step 4 with a second threshold to determine the horizontal position verification result, when both verification results meet the requirements, the current track passes the position validity verification;

[0024] Step 6, performing speed validity verification on the track passing the position validity verification, and judging the NACp value of the track, if the NACp value is greater than or equal to a preset value, then performing Step 7, otherwise, the track speed validity verification fails;

[0025] Step 7, calculating the acceleration of the current track based on the track speed according to the third difference value, if the acceleration based on the track speed is within a preset range, then performing Step 8, otherwise, the track speed validity verification fails;

[0026] Step 8, calculating the horizontal weighted average speed of the track based on the weighted sliding window method, if the track in the current track sliding window is the same as the track in Step 3, then the horizontal weighted average speed of the track directly uses the result of Step 3;

[0027] Step 9, comparing the weighted average speed calculated in Step 8 with a third threshold, and judging according to the M / N rule to obtain the speed validity verification result.

[0028] Optionally, Step 3 specifically includes:

[0029] According to the first difference value, the second difference value and the fourth difference value in Step 1, the speed of each track is obtained, the sliding window size is set to 4, then for the track at time t i , the update time of the previous 3 tracks is compared, based on the principle that the larger the time interval, the higher the weight value, four normalized weight values of different sizes are assigned to the four tracks, and the weighted average speed of the track at time t i is obtained

[0030] For the track at time t i+1 , the window also needs to be moved, ti+1 The time interval of the current track is compared with the size of the time interval of the previous three tracks, and a weight is assigned.

[0031] Optionally, the horizontal estimated acceleration of each track in step 4 is V i is the weighted average speed of the track at time t i is the weighted average speed of the track at time t i-1 is the weighted average speed of the track at time t i-1 is the weighted average speed of the track at time t i is the time value of the current track, time t i-1 is the time value of the previous track.

[0032] Optionally, the first threshold value in step 5 is 10000 ft / min, and the second threshold value is 14.7 m / s 2 .

[0033] Optionally, the preset value in step 6 is 7.

[0034] Optionally, in step 7, if the acceleration based on the track speed is less than or equal to 0.5 m / s 2 , then step 8 is performed.

[0035] Optionally, in step 9, the third threshold is 7 m / s.

[0036] In summary, the present application includes the following beneficial technical effects:

[0037] The method of the present application introduces an outlier detection mechanism before calculating the acceleration based on position data, which eliminates the influence of outliers on subsequent processing. For track data with small time intervals, a weighted assignment method is introduced, which gives higher weights to tracks with larger time intervals, and uses a weighted average speed instead of the speed calculation in the above position verification method and speed verification method, solving the problem of insufficient accuracy of existing verification methods in the case of small time intervals, effectively improving the accuracy of speed calculation and improving the accuracy of track validity verification.

[0038] The method of the present application combines multiple verification techniques to verify the data multiple times, improving the overall reliability of the data, reducing the impact of single verification errors, and enhancing data reliability.

[0039] The method of the present application is suitable for cases where the speed data quality is insufficient and the data fluctuates, and by dynamically adjusting the window length of the M / N criterion, the robustness of the M / N criterion is improved, the algorithm's resistance to fluctuating data is enhanced, and the method's applicability is improved.

[0040] The method optimizes the speed calculation process in position verification and speed verification, reduces the loss of computing resources, solves the problem of excessive calculation and resource waste in the position verification alternative method and the speed verification method, and improves the calculation efficiency. At the same time, based on the sliding window technology, multiple tracks are covered at each calculation to reduce the deviation of the verification result caused by single track calculation. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and all other drawings obtained by those skilled in the art without creative labor based on these drawings also belong to the protection scope of the present application.

[0042] Fig. 1 is a flowchart of the track validity verification method of the present application;

[0043] Fig. 2 is a schematic diagram of the speed calculation principle based on the weighted sliding window of the present application;

[0044] Fig. 3 is a schematic diagram of the speed validity verification flow of the present application;

[0045] Fig. 4 is a horizontal position verification and speed verification result diagram of the track verification method without smoothing;

[0046] Fig. 5 is a horizontal position verification and speed verification result diagram of the track verification method with smoothing;

[0047] Fig. 6 is a horizontal position verification and speed verification result diagram of the method of the present application. DETAILED DESCRIPTION

[0048] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0049] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0050] It is to be understood that the embodiments described hereinbelow within the scope of the appended claims. It will be apparent to one of ordinary skill in the art that aspects described herein can be implemented differently, and that any structure and / or function described herein is merely illustrative. Based on the teachings provided herein, a person of ordinary skill in the art will know that one aspect described herein can be implemented independent of any other aspect, and that two or more aspects can be combined in various ways. For example, an apparatus can be implemented or a method can be practiced using any number of the aspects set forth herein. In addition, such an apparatus can be implemented and / or such a method can be practiced using other structure and / or functionality in addition to or other than one or more of the aspects set forth herein.

[0051] It is also important to note that the drawings illustrated in the examples provided herein are for the purpose of illustrating aspects of the present application and are not to be construed as limiting the present application. In addition, it is well understood by those skilled in the art that unless otherwise indicated herein, the drawings are not to scale and that actual dimensions can be larger or smaller than those shown.

[0052] In addition, in the following description, numerous specific details are set forth in order to provide a thorough understanding of the examples. However, it will be apparent to one of ordinary skill in the art that the aspects described herein can be practiced without these specific details.

[0053] Embodiments of the present application provide a track validity verification method for an ADS-B monitoring application system.

[0054] As shown in FIG. 1 and FIG. 2, a track validity verification method for an ADS-B monitoring application system includes:

[0055] Position validity verification:

[0056] Step 1, pre-process the track data: calculate the difference between the horizontal position of the previous track and the current track as the first difference; calculate the difference between the vertical positions of the adjacent two tracks as the second difference; calculate the difference between the horizontal speeds of the adjacent two tracks as the third difference; calculate the difference between the applicable times of the adjacent two tracks as the fourth difference; wherein the first track is directly adopted.

[0057] Step 2, Outlier detection and filtering of the track, if the first difference of the track is within the preset range, then execute Step 3, otherwise, the track position validity verification fails. The outlier detection mechanism is introduced before the speed calculation, which makes a preliminary judgment on the track and filters the track with abnormal position data, preventing abnormal positions from affecting the subsequent smoothing process. In order to improve the accuracy and applicability of outlier detection, a dynamic threshold is adopted: outlier judgment threshold = maximum civil aviation cruise speed x adjacent track time interval. In addition, since the vertical position threshold 10000ft / min is an extreme case that exceeds normal flight, no outlier detection and filtering is performed on the vertical position.

[0058] Step 3, Calculate the speed based on the weighted sliding window method: calculate the horizontal weighted average speed and vertical weighted average speed of the track based on the weighted sliding window method.

[0059] Step 4, Calculate the acceleration based on the weighted average speed: calculate the horizontal estimated acceleration of each track according to the horizontal weighted average speed calculated in Step 3.

[0060] Step 5, Threshold comparison and judgment: compare the vertical weighted speed calculated in Step 3 with the first threshold to determine the vertical position verification result; compare the horizontal estimated acceleration calculated in Step 4 with the second threshold to determine the horizontal position verification result, when both verification results meet the requirements, the current track passes the position validity verification.

[0061] As shown in FIG. 3, the speed validity verification:

[0062] Step 6, NACp value detection and filtering: perform speed validity verification on the track that passes the position validity verification, and judge the NACp value of the track, if the NACp value is greater than or equal to the preset value, then execute Step 7, otherwise, the track speed validity verification fails.

[0063] Step 7, Calculate the acceleration based on the track speed and filter: calculate the acceleration based on the track speed of the current track according to the third difference, if the acceleration based on the track speed is within the preset range, then execute Step 8, otherwise, the track speed validity verification fails.

[0064] Step 8, Calculate the horizontal weighted average speed of the track based on the weighted sliding window method, if the track in the current track sliding window is the same as the track in Step 3, then the horizontal weighted average speed of the track directly uses the result of Step 3. When calculating the current track, the first few tracks that meet Steps 6 and 7 can be directly reused.

[0065] Step 9, compare the weighted average speed calculated in step 8 with the third threshold, and determine the speed validity verification result according to the M / N criterion, wherein the M / N criterion refers to that there are M track speeds less than the threshold in N tracks, and the value of N can be dynamically adjusted according to the acceleration calculated in step 7.

[0066] Through the above steps, the horizontal position, vertical position and horizontal speed data validity verification of the track can be realized. If it is desired to further improve the accuracy of track validity verification, the judgment threshold can be dynamically adjusted according to the aircraft state and historical data to ensure that the speed calculation can maintain high accuracy under different conditions.

[0067] Specifically:

[0068] The step 3 specifically includes:

[0069] According to the first difference, the second difference and the fourth difference in step 1, the speed of each track is calculated, and then the size of the sliding window is set to 3. For the track at time t i , the update time of the previous 3 tracks needs to be compared. Based on the principle that the larger the time interval, the higher the weight value, four normalized weight values of different sizes are assigned to the four tracks to obtain the weighted average speed of the track at time t i . For the track at time t i+1 , the window also needs to be moved, and the track at time t i+1 is compared with the previous 3 tracks in terms of time interval size and weight value again. The purpose of this is to improve the reliability of speed calculation. If the previous 3 tracks are compared, the first 3 tracks are directly passed.

[0070] The horizontal estimated acceleration of each track in step 4 , wherein V i is the weighted average speed of the track at time t i , V i-1 is the weighted average speed of the track at time t i-1 , t i is the time value of the current track, t i-1 is the time value of the previous track.

[0071] The first threshold value in step 5 is 10000 ft / min, and the second threshold value is 14.7 m / s 2 .

[0072] The preset value in step 6 is 7. Only the track that satisfies NACp≥7 can pass the speed verification, so the tracks that do not meet the requirements are filtered before the speed verification, saving resources consumed in subsequent processing.

[0073] The acceleration based on the track speed in step 7 is less than or equal to 0.5 m / s 2 Step 8 is performed, and since the speed verification method is only applicable to the uniform cruise stage of the aircraft, according to the description in DO-317, the speed verification method is only applicable to the case where the acceleration is less than or equal to 0.5 m / s 2 , the acceleration of the track is filtered before the speed comparison is performed.

[0074] In step 9, the third threshold is 7 m / s. The threshold for speed verification is also given by the DO-317 standard, and the value is 7 m / s. As shown in FIG. 4, if the calculated speed is less than the threshold, the pass flag is set to 1, and the track is sent to a queue with a length of N, and the last track in the queue is sent out of the queue. At this time, the pass flags of the N tracks in the queue are judged, and if the maximum lifetime of all the tracks is less than the required 25 s, and there are not less than M tracks passing among the tracks, at this time, the track speed verification passes. Otherwise, if the number of passing tracks in the N tracks is less than M, even if the calculated speed of the track is less than the threshold, the speed verification still fails.

[0075] In addition, for the case where the data fluctuates greatly, the value of N can be dynamically adjusted to improve the robustness of the M / N criterion. The method for judging whether the data fluctuates greatly is that, according to the acceleration calculated in step 7, the threshold is 0.5 m / s 2 , it can be set that when the acceleration is greater than 0.3 m / s 2 , the data is considered to fluctuate greatly.

[0076] The method of the present application solves the problem that the non-smooth track verification method is not applicable under the condition that the speed data is missing or the speed data quality is poor; solves the problem that the speed calculation and verification in the existing speed validity verification method exist delay; solves the problem that the horizontal position verification replacement method and the speed verification method based on the M / N criterion are not robust in the case of abnormal values or great track data fluctuations.

[0077] In order to further illustrate the advantages of the method of the present application, in the embodiment of the present application, MATLAB is used as a simulation platform, and the track of a certain aircraft received by a real machine test flight is used as simulation input. A total of 1424 ADS-B tracks are received, and the duration is 21 minutes and 57 seconds. The input track is subjected to horizontal position verification and speed verification by using the non-smooth position verification replacement method, the smooth position verification replacement method and the method of the present application respectively, and the results are shown in FIGS. 4 to 6 and Tables 1 and 2.

[0078] Firstly, according to Fig. 4, it can be seen that nearly half of the position verification results obtained by the position verification alternative method without smoothing exceed the set threshold, and mainly concentrate in the flight tracks with a time interval of about 0.5s. This result also verifies the effectiveness of the weight assignment based on time interval in the method of the present application.

[0079] Secondly, as shown in the following table, the accelerations calculated by Fig. 5 and Fig. 6 exceed the threshold, accounting for 43.9% and 16.1% of the total number of flight tracks, respectively. Considering that the input of this simulation is the ADS-B track received under normal environment, and the DO-317 standard indicates that 95% of the average flight tracks have more than 89% of the position data and speed data that can pass the verification. Therefore, the above two methods filter many flight tracks that actually meet the quality requirements. In contrast, only 39 flight tracks calculated by the method of the present application exceed the threshold, accounting for only 2.8% of the total number of flight tracks.

[0080] Finally, as shown in Table 1 and Table 2, although the speed verification results of the three methods are almost all in line with the requirements, since only the flight tracks that pass the position verification can be subjected to speed verification, the first two methods only have 794 and 1190 flight tracks participating in speed verification, respectively, and finally only 55.6% and 83.5% of the flight tracks pass both position verification and speed verification, which deviates too much from the reference value provided by the standard. In contrast, there are 1312 flight tracks participating in speed verification in the method of the present application, and only one flight track does not meet the requirements, and finally 92.1% of the flight tracks can pass both position verification and speed verification, which is in line with the description in the standard that 95% of the average flight tracks have more than 89% of the reports that can pass the verification. This result further illustrates that the first two methods incorrectly filter many flight tracks that meet the quality requirements in the position verification process.

[0081] Table 1 Horizontal position verification

[0082] Table 2 Speed verification

[0083] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A track validity verification method for an ADS-B monitoring application system, characterized in that, The method comprises the following steps: Step 1, pre-processing of track data: calculating the difference between the horizontal positions of the previous track and the current track as a first difference value; calculating the difference between the vertical positions of the adjacent two tracks as a second difference value; calculating the difference between the horizontal velocities of the adjacent two tracks as a third difference value; calculating the difference between the applicable times of the adjacent two tracks as a fourth difference value; Step 2, performing abnormal value detection on the track, if the first difference value of the track is within a preset range, then performing step 3, otherwise, the track position validity verification fails; Step 3, calculating the horizontal weighted average velocity and the vertical weighted average velocity of the track based on a weighted sliding window method; Step 4, calculating the horizontal estimated acceleration of each track according to the horizontal weighted average velocity calculated in step 3; Step 5, comparing the vertical weighted velocity calculated in step 3 with a first threshold to determine the vertical position verification result; comparing the horizontal estimated acceleration calculated in step 4 with a second threshold to determine the horizontal position verification result, and when both verification results meet the requirements, the current track passes the position validity verification; Step 6, performing speed validity verification on the track that passes the position validity verification, and judging the NACp value of the track, if the NACp value is greater than or equal to a preset value, then performing step 7, otherwise, the track speed validity verification fails; Step 7, calculating the track velocity-based acceleration of the current track according to the third difference value, if the track velocity-based acceleration is within a preset range, then performing step 8, otherwise, the track speed validity verification fails; Step 8, calculating the horizontal weighted average velocity of the track based on a weighted sliding window method, if the tracks in the sliding window of the current track are the same as the tracks in step 3, then the horizontal weighted average velocity of the track directly adopts the result of step 3; Step 9, comparing the weighted average velocity calculated in step 8 with a third threshold, and judging according to the M / N rule to obtain the speed validity verification result.

2. The track validity verification method for ADS-B surveillance application system according to claim 1, characterized in that, The step 3 specifically comprises: According to the first difference value, the second difference value and the fourth difference value in step 1, the speed of each track is calculated, and the sliding window size is set to 4. For the track at time t i , the update times of the previous 3 tracks are compared, based on the principle that the larger the time interval, the higher the weight value, 4 normalized weight values of different sizes are assigned to the 4 tracks, and the weighted average speed of the track at time t i is obtained For t i+1 The window is also moved to t i+1 The time interval size is compared and the weight is assigned to the track at t 3. The track validity verification method for ADS-B surveillance application system according to claim 1, characterized in that, the horizontal estimated acceleration of each track in step 4 where V i is the weighted average velocity of the track at time t i is the weighted average velocity of the track at time t i-1 is the weighted average velocity of the track at time t i-1 is the weighted average velocity of the track at time t i is the time value of the current track, time, t i-1 is the time value of the previous track.

4. The track validity verification method for ADS-B surveillance application system according to claim 1, characterized in that, The first threshold value in step 5 is 10000 ft / min and the second threshold value is 14.7 m / s 2 .

5. The track validity verification method for ADS-B surveillance application system according to claim 1, characterized in that, The preset value in step 6 is 7.

6. The track validity verification method for ADS-B surveillance application system according to claim 1, characterized in that, The acceleration in step 7 based on the track speed is less than or equal to 0.5 m / s 2 Step 8 is then executed.

7. The track validity verification method for ADS-B surveillance application system according to claim 1, characterized in that, In step 9, the third threshold is 7 m / s.

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