ADS-B monitoring application system-oriented track validity verification method

Abstract

The invention provides an ADS-B (Automatic Dependent Surveillance-Broadcast) monitoring application system-oriented track validity verification method, which belongs to the technical field of air traffic monitoring and specifically comprises the steps of introducing an abnormal value detection mechanism and eliminating the influence of an abnormal value on subsequent processing. And the weighted average speed is used for replacing other speed calculation methods. The M / N criterion is optimized according to the defects of the M / N criterion. Part of processing steps in horizontal position verification, horizontal speed verification and vertical position verification can be reused, resources are further saved, and verification efficiency is improved.

Description

Technical Field

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

[0002] Automatic Dependent Surveillance-Broadcast (ADS-B) is an advanced aviation surveillance technology that enables real-time monitoring of aircraft tracks by broadcasting information such as the position and speed of aircraft. The ADS-B surveillance application system is based on ADS-B IN reception. It monitors and processes the ADS-B received tracks and outputs ADS-B tracks that meet data quality requirements.

[0003] However, there are still quite a few early ADS-B devices that use relatively early standards, such as DO260 and DO260A. Such devices lack relevant data quality parameters or the quality parameters cannot reflect the actual data accuracy. In addition, the existing ADS-B equipment DO-260B also has the problem that the quality of the transmitted ADS-B data cannot meet the processing standards of the ADS-B surveillance application system. Therefore, in order to ensure that the existing ADS-B surveillance application system can receive enough tracks that meet the data quality requirements, a verification method for the validity of track data is needed.

[0004] Existing track validity verification methods include: non-smoothed track verification methods, which directly determine the validity of the horizontal position, horizontal speed and vertical speed data of adjacent tracks. However, this method is not suitable for situations where speed data is missing or the speed data quality is poor, and through analysis of the track data, when the time interval is small, there will be a large error in the position information of two adjacent tracks. To address this problem, an alternative method for smooth track horizontal position verification is proposed in the prior art. By increasing the length of the time window used in the calculation, the impact of time errors in position updates can be reduced.

[0005] In addition, in response to the problem that ADS-B equipment cannot provide effective speed quality indicators, the prior art also discloses a method for verifying the validity of speed based on position information. This method is applicable to the aircraft cruising process. Its main idea is to calculate the horizontal speed of the aircraft based on the aircraft position 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 of 7m / s. 2 The data is compared and the consistency is judged by the M / N criterion. The M / N criterion is that the speed difference of M tracks out of N tracks is less than the threshold.

[0006] By analyzing the validity verification methods proposed by the existing technologies, the shortcomings of the existing methods are summarized:

[0007] Main disadvantage 1: The non-smoothing track verification method proposed in the prior art is not suitable for situations where speed data is missing or the speed data quality is poor.

[0008] The second major disadvantage is that the existing method cannot guarantee the calculation accuracy when the time interval is small.

[0009] Main disadvantage 3: The horizontal position verification alternative method proposed in the prior art is based on the idea of ​​sliding windows. For each moment, the speed, position and time interval across multiple moments must be calculated, resulting in a significant increase in the amount of calculation. In addition, if there is an outlier at a certain moment, it will affect the acceleration calculation at multiple moments, which may cause the track that meets the quality requirements to be incorrectly filtered out.

[0010] Main disadvantage 4: The speed verification method based on position change proposed in the prior art has a large amount of calculation, and there is a delay of 2s-10s in speed calculation. At the same time, different speed calculation methods are used in position verification and speed verification, resulting in a significant increase in calculation amount and waste of resources.

[0011] Main disadvantage 5: Although the M / N criterion can resist the impact of single outliers, continuous outliers may affect the accuracy of the final judgment, and the M and N values ​​are generally fixed and cannot adapt to dynamic environments. Summary of the invention

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

[0013] The present application provides a method for verifying the validity of a track for an ADS-B surveillance application system using the following technical solutions:

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

[0015] Step 1: Preprocess the track data:

[0016] Calculate the difference between the horizontal position of the previous track and the current track as the first difference;

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

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

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

[0020] Step 2, perform outlier detection on the track. If the first difference of the track is within the preset range, execute step 3, otherwise, the track position validity verification fails;

[0021] Step 3, calculating the horizontal weighted average speed and 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 velocity calculated in step 3;

[0023] Step 5, compare the vertical weighted velocity calculated in step 3 with the first threshold to obtain the result of vertical position verification; compare the horizontal estimated acceleration calculated in step 4 with the second threshold to obtain the result of horizontal position verification. When both verification results meet the requirements, the current track passes the position validity verification;

[0024] Step 6, perform speed validity verification on the track that has passed 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, execute 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, if the acceleration based on the track speed is within a preset range, executing step 8, otherwise, the track speed validity verification fails;

[0026] Step 8, calculate the track horizontal weighted average speed 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, the track horizontal weighted average speed directly adopts the result of step 3;

[0027] Step 9, comparing the weighted average speed calculated in step 8 with the third threshold, and making a judgment based on the M / N criterion to obtain a speed validity verification result.

[0028] Optionally, the step 3 specifically includes:

[0029] The speed of each track is calculated based on the first difference, the second difference, and the fourth difference in step 1. The sliding window size is set to 4. Then for t i The track at time t needs to be compared with the update time of the first three tracks. Based on the principle that the larger the time interval, the higher the weight, the four normalized weights of different sizes are assigned to the four tracks, and t is obtained. i Weighted average speed of the track at any moment

[0030] For t i+1 The window should also be moved to show the track at time t i+1The time interval between the track at the moment and the three previous tracks is compared and weighted again.

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

[0032] Optionally, in step 5, the first threshold value 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, the acceleration based on the track speed in step 7 is less than or equal to 0.5 m / s 2 Then proceed to step 8.

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

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

[0037] The present application method introduces an outlier detection mechanism before calculating the acceleration based on the position data to eliminate the impact of outliers on subsequent processing. For track data with a small time interval, a weighted assignment method is introduced to assign higher weights to tracks with a large time interval, and a weighted average speed is used to replace the speed calculation in the above-mentioned position verification method and speed verification method, solving the problem of insufficient accuracy of the existing verification method when the time interval is small, effectively improving the accuracy of speed calculation, and improving the accuracy of track validity verification.

[0038] The present application method combines multi-layer verification technology to verify the data multiple times, thereby improving the overall reliability of the data, reducing the impact caused by single verification errors, and enhancing data reliability.

[0039] The method of the present application is applicable to situations 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 ability to resist fluctuating data is enhanced, and the applicability of the method is improved.

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

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 This is a flowchart of the track validity verification method for this application;

[0043] Figure 2 This is a schematic diagram of the speed calculation principle based on the weighted sliding window of this application;

[0044] Figure 3 This is a schematic diagram of the speed validity verification process for this application;

[0045] Figure 4 This is the horizontal position verification and speed verification result diagram of the unsmoothed track verification method;

[0046] Figure 5 The horizontal position verification and speed verification result diagram of the smooth track verification method;

[0047] Figure 6 This is the horizontal position verification and speed verification result diagram of this application method. DETAILED DESCRIPTION

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

[0049] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0050] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0051] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show the components related to the present application rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0052] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0053] An embodiment of the present application provides a track validity verification method for an ADS-B surveillance application system.

[0054] like Figure 1 and Figure 2 As shown, a track validity verification method for an ADS-B surveillance application system includes:

[0055] Location validity verification:

[0056] Step 1, preprocess 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 two adjacent tracks as the second difference; calculate the difference between the horizontal speeds of two adjacent tracks as the third difference; calculate the difference between the applicable times of two adjacent tracks as the fourth difference; among them, the first track is directly adopted.

[0057] Step 2, perform outlier detection and filtering on the track. If the first difference of the track is within the preset range, execute step 3, otherwise, the track position validity verification fails. Before calculating the speed, an outlier detection mechanism is introduced to make a preliminary judgment on the track and filter the track with abnormal position data to prevent the abnormal position 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 cruising speed of civil aviation × time interval between adjacent tracks. In addition, since the vertical position threshold of 10,000 ft / min is itself an extreme case beyond normal flight, outlier detection and filtering are not 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 the vertical weighted average speed of the track based on the weighted sliding window method.

[0059] Step 4, calculate acceleration based on 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 and judge the vertical weighted velocity calculated in step 3 with the first threshold to obtain the result of vertical position verification; compare and judge the horizontal estimated acceleration calculated in step 4 with the second threshold to obtain the result of horizontal position verification. When both verification results meet the requirements, the current track passes the position validity verification.

[0061] like Figure 3 As shown, 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, execute step 7, otherwise, the track speed validity verification fails.

[0063] Step 7, calculate and filter the acceleration based on the track speed: 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, 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, the horizontal weighted average speed of the track directly uses the result of step 3. When calculating the current track, the first few tracks of interest all meet steps 6 and 7 and can be reused directly.

[0065] Step 9, compare the weighted average speed calculated in step 8 with the third threshold, and judge according to the M / N criterion to obtain the speed validity verification result, wherein the M / N criterion means: the speed difference of M tracks out of N tracks is less than the threshold, and the N value can be dynamically adjusted according to the acceleration calculated in step 7.

[0066] The above steps can realize the validity verification of the horizontal position, vertical position and horizontal speed data in the track. If you want to further improve the accuracy of the track validity verification, you can dynamically adjust the judgment threshold according to the aircraft status and historical data to ensure that the speed calculation in different situations can maintain a high accuracy.

[0067] Specific:

[0068] The step 3 specifically includes:

[0069] The speed of each track is calculated based on the first difference, the second difference, and the fourth difference in step 1. Then, the sliding window size is set to 3. For t i The track at time t needs to be compared with the update time of the first three tracks. Based on the principle that the larger the time interval, the higher the weight, the four normalized weights of different sizes are assigned to the four tracks, and t is obtained. i Weighted average speed of the track at any moment For t i+1 The window should also be moved to show the track at time t i+1 The time interval between the track at the moment and the three previous tracks is compared and weighted again. This is to improve the reliability of speed calculation. If the first three tracks are to be compared, the first three tracks are directly passed.

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

[0071] In step 5, the first threshold value 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 tracks that satisfy NACp≥7 can pass the speed verification, so before performing the speed verification, the tracks that do not meet the requirements are filtered out to save resources consumed by subsequent processing.

[0073] The acceleration based on the track speed in step 7 is less than or equal to 0.5m / s 2 Then execute step 8. Since the speed verification method is only applicable to the aircraft's constant speed cruise phase, according to the description in DO-317, the speed verification method is only applicable to acceleration ≤ 0.5m / s 2 Therefore, before comparing the speeds, we first filter out the tracks whose acceleration does not meet the requirements.

[0074] In step 9, the third threshold is 7m / s. The threshold for speed verification is also given by the DO-317 standard and is 7m / s. Figure 4 As shown in the figure, if the calculated speed is less than the threshold, the passing flag is set to 1, and the track is sent into a queue of length N. At the same time, the last track in the queue is sent out of the queue. The passing flags of the N tracks in the queue are judged. If the maximum life of all tracks is less than the required 25s, and no less than M tracks pass through these tracks, the speed verification of the track is passed. On the contrary, if the number of tracks passing through the N tracks is less than M, then even if the calculated speed of the track is less than the threshold, it still cannot pass the speed verification.

[0075] In addition, for cases where data fluctuations are large, the value of N can be dynamically adjusted to improve the robustness of the M / N criterion. The method for determining when data fluctuations are large is to use the acceleration calculated in step 7 with a threshold requirement of 0.5 m / s 2 , you can set when the acceleration is greater than 0.3m / s 2 The data is considered to be volatile.

[0076] The method of the present application solves the problem that the non-smoothed track verification method is not applicable when the speed data is missing or the speed data quality is poor; solves the problem that there is a delay in speed calculation and verification in the existing speed validity verification method; solves the problem that the horizontal position verification alternative method and the speed verification method based on the M / N criterion are not robust enough when there are outliers or large fluctuations in the track data.

[0077] In order to further illustrate the advantages of the method of the present application, MATLAB is used as a simulation platform, and the track of a certain aircraft received by the actual test flight is used as the simulation input. A total of 1424 ADS-B tracks are received, and the duration is 21 minutes and 57 seconds. The position verification alternative method without smoothing, the position verification alternative method with smoothing, and the method of the present application are used to perform horizontal position verification and speed verification on the input track, and the results are shown as follows: Figures 4 to 6 As shown in Tables 1 and 2.

[0078] First, according to Figure 4As shown in the figure, it can be seen that nearly half of the position verification results obtained by the non-smoothed position verification alternative method exceed the set threshold, and are mainly concentrated in the tracks with a time interval of about 0.5s. This result also indirectly verifies the effectiveness of the weight assignment calculation speed based on the time interval in the method of this application.

[0079] Secondly, as shown in the following table, Figure 5 and Figure 6 Among the calculated accelerations, those exceeding the threshold accounted for 43.9% and 16.1% of the total number of tracks, respectively. Considering that the simulation input is the ADS-B track received under normal conditions, and the DO-317 standard states that an average of 95% of the tracks have more than 89% of the position data and velocity data that can pass verification. Therefore, the above two methods filter out many tracks that actually meet the quality requirements. In contrast, the acceleration calculated by the present application method only exceeds the threshold for 39 tracks, accounting for only 2.8% of the total number of tracks.

[0080] Finally, as shown in Tables 1 and 2, although the speed verification results of the three methods almost all meet the requirements, since only tracks that have passed the position verification can undergo speed verification, the first two methods only have 794 and 1190 tracks involved in speed verification, respectively. In the end, only 55.6% and 83.5% of the tracks passed both the position verification and the speed verification, respectively, which is too far from the reference values ​​provided by the standard. In contrast, in the method of this application, 1312 tracks participated in speed verification, and only one track did not meet the requirements. In the end, 92.1% of the tracks were able to pass both the position verification and the speed verification, which meets the description in the standard that an average of 95% of the tracks have more than 89% of the reports that can pass verification. This result also further illustrates that the first two methods incorrectly filter out many tracks that meet the quality requirements during the position verification process.

[0081] Table 1 Horizontal position verification

[0082]

[0083]

[0084] Table 2 Speed ​​verification

[0085]

[0086] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A track validity verification method for an ADS-B surveillance application system, characterized in that: include: Step 1: Preprocess 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 two adjacent tracks as the second difference; Calculate the difference between the horizontal velocities of two adjacent tracks as the third difference; Calculate the difference between the applicable times of two adjacent tracks as the fourth difference; Step 2, perform outlier detection on the track. If the first difference of the track is within the preset range, execute step 3, otherwise, the track position validity verification fails; Step 3, calculating the horizontal weighted average speed and vertical weighted average speed of the track based on the 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 the first threshold to obtain a result of vertical position verification; Compare the horizontal estimated acceleration calculated in step 4 with the second threshold to obtain a horizontal position verification result. When both verification results meet the requirements, the current track passes the position validity verification. Step 6, perform speed validity verification on the track that has passed 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, execute step 7, otherwise, the track speed validity verification fails; Step 7, calculating the acceleration of the current track based on the track speed according to the third difference, if the acceleration based on the track speed is within a preset range, executing step 8, otherwise, the track speed validity verification fails; Step 8, calculate the track horizontal weighted average speed 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, the track horizontal weighted average speed directly adopts the result of step 3; Step 9, comparing the weighted average speed calculated in step 8 with the third threshold, and making a judgment based on the M / N criterion to obtain a speed validity verification result.

2. The track validity verification method for the ADS-B surveillance application system according to claim 1, characterized in that: The step 3 specifically includes: The speed of each track is calculated based on the first difference, the second difference, and the fourth difference in step 1. The sliding window size is set to 4. Then for t i The track at time t needs to be compared with the update time of the first three tracks. Based on the principle that the larger the time interval, the higher the weight, the four normalized weights of different sizes are assigned to the four tracks, and t is obtained. i Weighted average speed of the track at any moment For t i+1 The window should also be moved to show the track at time t i+1 The time interval between the track at the moment and the three previous tracks is compared and weighted again.

3. The track validity verification method for the ADS-B surveillance application system according to claim 1, characterized in that: The estimated horizontal acceleration of each track in step 4 Among them, V i t i The weighted average speed of the track at the moment, V i-1 t i-1 The weighted average speed of the track at time t i is the time value of the current track, time, t i-1 It is the time value of the previous track.

4. The track validity verification method for the ADS-B surveillance application system according to claim 1, characterized in that: In step 5, the first threshold value is 10000 ft / min, and the second threshold value is 14.7 m / s2.

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

7. The track validity verification method for the 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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