A method for verifying the validity of flight tracks in ADS-B surveillance application systems

Abstract

This application provides a method for verifying the validity of flight tracks in ADS-B surveillance application systems, belonging to the field of air traffic surveillance technology. Specifically, it includes introducing an outlier detection mechanism to eliminate the impact of outliers on subsequent processing; using a weighted average speed instead of other speed calculation methods; and optimizing the M / N criterion to address its shortcomings. Some processing steps in horizontal position verification, horizontal speed verification, and vertical position verification can be reused, further saving resources and improving verification efficiency.

Description

Technical Field

[0001] This application relates to the field of air traffic surveillance, and in particular to a method for verifying the validity of flight tracks for ADS-B surveillance application systems. Background Technology

[0002] Automatic Dependent Surveillance-Broadcast (ADS-B) is an advanced airborne surveillance technology that broadcasts information such as the aircraft's position and speed to enable real-time monitoring of the aircraft's trajectory. The ADS-B surveillance application system is built upon ADS-B IN reception, and through monitoring and processing of the received ADS-B trajectories, it outputs ADS-B trajectories that meet data quality requirements.

[0003] However, many early ADS-B devices still use older standards, such as DO260 and DO260A. These devices suffer from a lack of relevant data quality parameters or the parameters failing to reflect the actual data accuracy. Furthermore, the existing DO-260B ADS-B device also exhibits issues where the quality of transmitted ADS-B data does not meet the processing standards of ADS-B surveillance applications. Therefore, to ensure that existing ADS-B surveillance applications can receive a sufficient number of tracks that meet data quality requirements, a method for verifying the validity of track data is needed.

[0004] Existing track validity verification methods include: non-smoothing track verification methods, which directly determine the validity of horizontal position, horizontal velocity, and vertical velocity data of adjacent tracks. However, this method is not suitable for situations where velocity data is missing or of poor quality, and analysis of track data reveals significant errors in the position information of adjacent tracks when the time interval is short. To address this issue, an alternative method for smoothed track horizontal position verification has been proposed in the prior art. By increasing the duration of the time window used in the calculation, the impact of time errors in position updates can be reduced.

[0005] In addition, to address the issue that ADS-B equipment cannot provide effective speed quality indicators, existing technology also discloses a method for verifying speed validity based on position information. This method is applicable during aircraft cruise. Its main idea is to calculate the aircraft's horizontal speed by taking advantage of the aircraft's position within 2-10 seconds before and after the current flight path, and then applying the difference between the calculated speed and the speed in the flight path to a threshold of 7 m / s. 2 The data are compared and the consistency is judged by the M / N criterion, which states that the speed difference of M out of N tracks is less than a threshold.

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

[0007] The main drawback is that the existing non-smooth track verification method is not suitable for situations where speed data is missing or the speed data quality is poor.

[0008] The second major drawback is that existing methods cannot guarantee computational accuracy when the time interval is short.

[0009] The third major drawback is that the existing horizontal position verification alternatives are based on the sliding window concept, requiring the calculation of velocity, position, and time intervals across multiple moments for each moment, resulting in a significant increase in computational load. Furthermore, if outliers exist at any moment, they can affect the acceleration calculations at multiple moments, potentially leading to the incorrect filtering out of tracks that meet quality requirements.

[0010] The fourth major drawback is that existing velocity verification methods based on position changes involve significant computational costs, and velocity calculations are delayed by 2-10 seconds. Furthermore, the use of different velocity calculation methods in position and velocity verification leads to a substantial increase in computational load and wasted resources.

[0011] Fifth major drawback: Although the M / N criterion can resist the influence of a single outlier, consecutive 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, this application provides a method for verifying the validity of flight tracks in an ADS-B surveillance application system, which solves the problems in the prior art and improves the accuracy of flight track validity verification.

[0013] This application provides a method for verifying the validity of flight tracks in an ADS-B surveillance application system, which employs the following technical solution:

[0014] A method for verifying the validity of flight tracks in an ADS-B surveillance application system includes:

[0015] Step 1, Preprocessing track data:

[0016] The difference between the horizontal position of the previous track and the current track is calculated as the first difference.

[0017] Calculate the difference in vertical position between two adjacent flight paths as the second difference;

[0018] The difference in horizontal velocity between two adjacent tracks is calculated as the third difference.

[0019] The difference in applicable time between two adjacent flight paths is calculated 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, proceed to Step 3; otherwise, the track position validity verification fails.

[0021] Step 3: Calculate the horizontally weighted average velocity and the vertically weighted average velocity of the trajectory based on the weighted sliding window method;

[0022] Step 4: Calculate the estimated horizontal acceleration for each track based on 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 vertical position verification result; compare the horizontal estimated acceleration calculated in Step 4 with the second threshold to obtain the horizontal position verification result. When both verification results meet the requirements, the current track passes the position validity verification.

[0024] Step 6: Verify the speed validity of the track that has passed the position validity verification. Determine the NACp value of the track. If the NACp value is greater than or equal to the preset value, proceed to step 7; otherwise, the speed validity verification of the track fails.

[0025] Step 7: Calculate 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 the preset range, proceed to step 8; otherwise, the track speed validity verification fails.

[0026] Step 8: Calculate the horizontal weighted average velocity 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 velocity of the track is directly taken from the result of step 3.

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

[0028] Optionally, step 3 specifically includes:

[0029] Calculate the velocity of each track based on the first, second, and fourth differences from step 1. Set the sliding window size to 4. Then, for t... i The trajectory at time t needs to be compared with the update times of the previous three trajectories. Based on the principle that the larger the time interval, the higher the weight, four normalized weights of different magnitudes are assigned to the four trajectories to obtain t. i Weighted average speed of the time track

[0030] For t i+1 The timeline also needs to be adjusted, and the window needs to be moved accordingly. i+1The time interval between the current trajectory and its three preceding trajectories is compared and weighted.

[0031] Optionally, the horizontal acceleration estimated for each track in step 4. Among them, V i For t i The weighted average velocity of the time-track, V i-1 For t i-1 The weighted average velocity of the trajectory at time t i The time value of the current trajectory, time t i-1 This is the time value of the previous flight path.

[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, in step 7, the acceleration based on the trajectory velocity is less than or equal to 0.5 m / s². 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] This application's method introduces an outlier detection mechanism before calculating acceleration based on position data to eliminate the impact of outliers on subsequent processing. For track data with short time intervals, a weighted assignment method is introduced, giving higher weights to tracks with longer time intervals. Furthermore, a weighted average velocity is used to replace the velocity calculations in the aforementioned position and velocity verification methods. This addresses the issue of insufficient accuracy in existing verification methods when time intervals are short, effectively improving the accuracy of velocity calculation and thus enhancing the accuracy of track validity verification.

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

[0039] The method described in this application is applicable to situations where velocity data quality is insufficient and data fluctuations occur. Furthermore, by dynamically adjusting the window length of the M / N criterion, the robustness of the M / N criterion is improved, enhancing the algorithm's ability to withstand fluctuating data and increasing the applicability of the method.

[0040] This application's method optimizes the velocity calculation process in position and velocity verification, reducing computational resource consumption and addressing the issues of excessive computation and resource waste in alternative position and velocity verification methods, thus improving computational efficiency. Furthermore, based on the sliding window technique, multiple tracks are covered in each calculation, reducing the deviation in verification results caused by calculations on a single track. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a flowchart illustrating the method for verifying the validity of the flight track in this application;

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

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

[0045] Figure 4 The results of horizontal position and velocity verification for the non-smoothed trajectory verification method are shown in the figure.

[0046] Figure 5 The results of horizontal position verification and velocity verification are shown in the figure for the smooth flight path verification method;

[0047] Figure 6 The diagram shows the results of horizontal position verification and velocity verification of the method in this application. Detailed Implementation

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

[0049] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one 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 set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0051] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

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

[0053] This application provides a method for verifying the validity of flight tracks in an ADS-B surveillance application system.

[0054] like Figure 1 and Figure 2 As shown, a method for verifying the validity of flight tracks in an ADS-B surveillance application system includes:

[0055] Location validity verification:

[0056] Step 1, Preprocess the track data: Calculate the difference in horizontal position between the previous track and the current track as the first difference; calculate the difference in vertical position between two adjacent tracks as the second difference; calculate the difference in horizontal speed between two adjacent tracks as the third difference; calculate the difference in applicable time between two adjacent tracks as the fourth difference; wherein, the first track is used directly.

[0057] Step 2 involves outlier detection and filtering of the flight track. If the first difference in the track's position is within a preset range, proceed to Step 3; otherwise, the track's position validity verification fails. An outlier detection mechanism is introduced before speed calculation to preliminarily assess the track and filter tracks with abnormal position data, preventing abnormal positions from affecting subsequent smoothing processes. To improve the accuracy and applicability of outlier detection, a dynamic threshold is used: Outlier Judgment Threshold = Maximum Civil Aviation Cruise Speed ​​× Time Interval Between Adjacent Tracks. Furthermore, since the vertical position threshold of 10,000 ft / min is itself an extreme case exceeding normal flight, outlier detection and filtering are not performed on the vertical position.

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

[0059] Step 4, calculate acceleration based on weighted average velocity: Calculate the estimated horizontal acceleration for each track based on the horizontal weighted average velocity calculated in Step 3.

[0060] Step 5, Threshold Comparison and Judgment: Compare the vertical weighted velocity calculated in Step 3 with the first threshold to obtain the vertical position verification result; compare the horizontal estimated acceleration calculated in Step 4 with the second threshold to obtain the horizontal position verification result. 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 has passed the position validity verification. Judge the NACp value of the track. If the NACp value is greater than or equal to the preset value, proceed to 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, proceed to step 8; otherwise, the track speed validity verification fails.

[0064] Step 8: Calculate the horizontally weighted average velocity of the track using the weighted sliding window method. If the track within the current sliding window is the same as the track in Step 3, the horizontally weighted average velocity of the track is directly taken from the result of Step 3. When calculating for the current track, if the first few tracks of interest meet the requirements of Steps 6 and 7, they can be directly reused.

[0065] Step 9: Compare the weighted average speed calculated in Step 8 with the third threshold, and make a judgment based on the M / N criterion to obtain the speed validity verification result. The M / N criterion means that the speed difference of M tracks out of N tracks is less than the threshold. The value of N can be dynamically adjusted according to the acceleration calculated in Step 7.

[0066] The above steps can be used to verify the validity of horizontal position, vertical position, and horizontal speed data in the flight path. If you want to further improve the accuracy of the flight path validity verification, you can dynamically adjust the judgment threshold based on the aircraft status and historical data to ensure that the speed calculation can maintain high accuracy under different conditions.

[0067] Specifically:

[0068] Step 3 specifically includes:

[0069] Calculate the velocity of each track based on the first, second, and fourth differences from step 1. Then, set the sliding window size to 3. For t... i The trajectory at time t needs to be compared with the update times of the previous three trajectories. Based on the principle that the larger the time interval, the higher the weight, four normalized weights of different magnitudes are assigned to the four trajectories to obtain t. i Weighted average speed of the time track For t i+1 The timeline also needs to be adjusted, and the window needs to be moved accordingly. i+1 The time interval between the current trajectory and its three preceding trajectories is recalculated and weighted. This improves the reliability of velocity calculation. If the first three trajectories are to be compared, they are passed directly.

[0070] The horizontal acceleration estimation for each track in step 4 Among them, V i For t i The weighted average velocity of the time-track, V i-1 For t i-1 The weighted average velocity of the trajectory at time t i The time value of the current trajectory, time t i-1 This is the time value of the previous flight path.

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

[0072] In step 6, the preset value is 7; only tracks that meet NACp≥7 can pass the speed verification. Therefore, tracks that do not meet the requirements are filtered out before speed verification to save resources consumed in subsequent processing.

[0073] In step 7, the acceleration based on the trajectory velocity is less than or equal to 0.5 m / s². 2 Then proceed to step 8. Since the speed verification method is only applicable to the constant speed cruise phase of the aircraft, according to the description in DO-317, the speed verification method is only applicable to accelerations ≤0.5m / s². 2 Therefore, tracks whose acceleration does not meet the requirements are filtered out before speed comparison.

[0074] In step 9, the third threshold is 7 m / s. The speed verification threshold is also given by the DO-317 standard, with a value of 7 m / s. Figure 4 As shown, if the calculated speed is less than the threshold, the pass flag is set to 1, and the track is added to a queue of length N. Simultaneously, the last track in the queue is removed. The pass flags of the N tracks in the queue are then checked. If the maximum lifetime of all tracks is less than the required 25 seconds, and at least M tracks have passed, then the speed verification for that track is successful. Conversely, if fewer than M tracks have passed, the speed verification fails even if the calculated speed is less than the threshold.

[0075] In addition, for cases with significant data fluctuations, the value of N can be dynamically adjusted to improve the robustness of the M / N criterion. The method for determining significant data fluctuations is to use the acceleration calculated in step 7, with a threshold requirement of 0.5 m / s². 2 It can be set to work when the acceleration is greater than 0.3 m / s². 2 This is considered to be a time of significant data fluctuation.

[0076] The method of this application solves the problem that continuous track verification methods without smoothness are not applicable when speed data is missing or of poor quality; it solves the problem of delay in speed calculation and verification in existing speed validity verification methods; and it 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 track data.

[0077] To further illustrate the advantages of the method in this application, MATLAB was used as the simulation platform in this embodiment. The flight path of an aircraft received during a real flight test was used as the simulation input. A total of 1424 ADS-B flight paths were received, lasting 21 minutes and 57 seconds. The horizontal position and velocity were verified using a non-smoothing position verification replacement method, a smoothing position verification replacement method, and the method of this application, respectively. The results are as follows: Figures 4 to 6 As shown in Tables 1 and 2.

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

[0079] Secondly, as shown in the table below. Figure 5 and Figure 6 Of the calculated accelerations, those exceeding the thresholds accounted for 43.9% and 16.1% of the total tracks, respectively. Considering that the simulation input consisted of ADS-B tracks received under normal conditions, and that the DO-317 standard states that, on average, 95% of tracks have over 89% of their position and velocity data that can be verified, the two methods mentioned above filtered out many tracks that actually met the quality requirements. In contrast, the acceleration calculated by the method in this application only exceeded the threshold for 39 tracks, accounting for only 2.8% of the total tracks.

[0080] Finally, as shown in Tables 1 and 2, although the speed verification results of the three methods almost all met the requirements, only tracks that passed position verification could undergo speed verification. Therefore, only 794 and 1190 tracks, respectively, participated in speed verification for the first two methods, resulting in only 55.6% and 83.5% of the tracks passing both position and speed verifications simultaneously, significantly deviating from the reference values ​​provided by the standard. In contrast, the method in this application had 1312 tracks participating in speed verification, with only one track failing to meet the requirements. Ultimately, 92.1% of the tracks passed both position and speed verifications simultaneously, meeting the standard's description that an average of 95% of tracks had over 89% of reports passing verification. This result further illustrates that the first two methods incorrectly filtered out many tracks that met 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 description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for verifying the validity of flight tracks in an ADS-B surveillance application system, characterized in that, include: Step 1, Preprocessing track data: The difference between the horizontal position of the previous track and the current track is calculated as the first difference. The difference in vertical position between two adjacent tracks is used as the second difference. The difference in horizontal velocity between two adjacent tracks is calculated as the third difference. The difference in applicable time between two adjacent flight paths is calculated as the fourth difference. Step 2: Perform outlier detection on the track. If the first difference of the track is within the preset range, proceed to Step 3; otherwise, the track position validity verification fails. Step 3: Calculate the horizontally weighted average velocity and the vertically weighted average velocity of the trajectory based on the weighted sliding window method; Step 4: Calculate the estimated horizontal acceleration for each track based on the horizontal weighted average velocity calculated in Step 3; Step 5: Compare the vertical weighted average velocity calculated in Step 3 with the first threshold to obtain the result of vertical position verification. The horizontal estimated acceleration calculated in step 4 is compared with the second threshold to determine the horizontal position verification result. If both verification results meet the requirements, the current track passes the position validity verification. Step 6: Verify the speed validity of the track that has passed the position validity verification. Determine the NACp value of the track. If the NACp value is greater than or equal to the preset value, proceed to step 7; otherwise, the speed validity verification of the track fails. Step 7: Calculate 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 the preset range, proceed to step 8; otherwise, the track speed validity verification fails. Step 8: Calculate the horizontal weighted average velocity 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 velocity of the track is directly taken from the result of step 3. Step 9: Compare the horizontal weighted average speed calculated in Step 8 with the third threshold, and make a judgment based on the M / N criterion to obtain the speed validity verification result.

2. The method for verifying the validity of flight tracks for ADS-B surveillance application systems according to claim 1, characterized in that, Step 3 specifically includes: Calculate the velocity of each track based on the first, second, and fourth differences from step 1. Set the sliding window size to 4. Then, for... The track at a given time needs to be compared with the update times of the previous three tracks. Based on the principle that the larger the time interval, the higher the weight, four normalized weights of unequal magnitude are assigned to the four tracks to obtain the result. Weighted average speed of the time track ; for The flight path at any given time also needs to be moved along with the window. The time interval between the current trajectory and its three preceding trajectories is compared and weighted.

3. The method for verifying the validity of flight tracks for ADS-B surveillance application systems according to claim 1, characterized in that, The horizontal acceleration estimation for each track in step 4 ,in, for Horizontally weighted average velocity of the flight path at any given time for The horizontally weighted average velocity of the trajectory at any given time. The time value of the current trajectory, time This is the time value of the previous flight path.

4. The method for verifying the validity of flight tracks for ADS-B surveillance application systems 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 method for verifying the validity of flight tracks for ADS-B surveillance application systems according to claim 1, characterized in that, The preset value in step 6 is 7.

6. The method for verifying the validity of flight tracks for ADS-B surveillance application systems according to claim 1, characterized in that, In step 7, the acceleration based on the trajectory velocity is less than or equal to 0.5 m / s². 2 Then proceed to step 8.

7. The method for verifying the validity of flight tracks for ADS-B surveillance application systems according to claim 1, characterized in that, In step 9, the third threshold is 7 m / s.

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