A forward-looking predictive alarm implementation method for an enhanced ground proximity alarm system

Abstract

This invention provides a forward-looking prediction alarm implementation method for an enhanced ground proximity warning system. First, a forward-looking prediction alarm envelope is established. Then, based on the forward-looking prediction alarm envelope and the aircraft's current position, terrain data blocks are provided in a digital terrain database. The digital terrain database is stored in a hierarchical manner. When the digital terrain database is divided into 13 levels, the terrain database is divided into 2... 13 Each terrain data sub-block contains a certain number of terrain data sub-blocks. It determines whether each terrain data sub-block is within the forward look-ahead prediction (FAY) warning envelope, and saves the terrain data sub-blocks within the FAY warning envelope. Each terrain data sub-block contains 256 grids, and it determines whether the grid elevation data in the saved terrain data sub-blocks is greater than the height corresponding to the FAY warning envelope. The beneficial effects of this invention are: it can satisfy different aircraft characteristics and different FAY warning envelopes, and has wide applicability.

Description

Technical Field

[0001] This invention relates to avionics technology, and in particular, to a method for implementing the forward-looking prediction warning function of an enhanced ground proximity warning system. Background Technology

[0002] The Enhanced Ground Proximity Warning System (EPWS) includes six basic warning modes, Forward Look-Ahead Predictive Warning (FTPS), and terrain display functionality. This system significantly reduces the occurrence of controllable flight accidents. FTPS is a crucial component of the EPWS, providing comprehensive warning protection for the aircraft. However, the implementation methods for FTPS are relatively limited, requiring in-depth and systematic research. Summary of the Invention

[0003] The purpose of this invention is to provide a forward-looking prediction alarm implementation method for an enhanced ground proximity warning system. Forward-looking prediction alarm is an important component of the enhanced ground proximity warning system, which can provide aircraft with alarm protection throughout the entire process.

[0004] To achieve the above objectives, the present invention provides a forward-looking predictive alarm implementation method for an enhanced ground proximity alarm system, comprising the following steps:

[0005] Step S1: Calculate the forward-looking prediction warning envelope of the enhanced ground proximity warning system based on the aircraft's ground speed, heading, track inclination, maximum climb angle, wingspan, pilot's reserved reaction time, maneuver pull-up time, and climb time.

[0006] Step S2: Scan the digital terrain database based on the forward-looking detection distance (LAD) and the aircraft's position information according to the forward-looking prediction alarm envelope, and extract terrain data blocks; extract terrain data sub-blocks and grids according to the hierarchical storage method of the digital terrain database, and sequentially determine whether the terrain data sub-blocks and grids are within the forward-looking prediction alarm envelope.

[0007] Step S3: Extract the grid elevation data within the forward-looking prediction alarm envelope and compare it with the height of the forward-looking prediction alarm envelope to perform a collision avoidance assessment.

[0008] Step S4: If the elevation data of the grid is greater than the height of the corresponding forward-looking prediction alarm envelope, execute voice and character alarms.

[0009] Furthermore,

[0010] The forward-looking prediction warning envelope and forward-looking detection range (LAD) are calculated based on the aircraft's ground speed, pilot's reaction time, pull-up time, and climb time. The detection width (D) of the forward-looking prediction warning envelope is determined based on the aircraft's wing width.

[0011] The downward distance H of the descent segment of the forward look-ahead warning envelope (the segment corresponding to the pilot's reaction time and pull-up time) is calculated based on the aircraft's flight path angle. 下 The upward distance H of the rising segment of the forward-looking prediction warning envelope (the segment of the forward-looking prediction warning envelope corresponding to the climb time) can be calculated based on the aircraft's maximum climb angle. 上 ;

[0012] Because aircraft need to maintain a certain safe clearance altitude from the ground, and due to factors such as the accuracy of the digital terrain database, the accuracy of measuring elements, and system errors, the forward-looking prediction alarm envelope should include a downward safe altitude H. c .

[0013] Furthermore,

[0014] Based on the calculated forward-looking pre-detection distance (LAD) and detection width (D), determine the radius. Draw a circle with the aircraft's current position O as the center and R as the radius. Then, construct an circumscribed square around this circle along the north-south direction, ensuring the square encompasses the entire circle. Locate the aircraft's current position in the digital terrain database and extract the square described above; this square is denoted as the terrain data block.

[0015] Digital terrain databases are divided and stored in different layers. Assuming the entire terrain data is divided into N layers, this means it is divided into 2 layers along both the longitude and latitude directions. N Each sub-block represents a degree in the longitude direction. Each sub-block represents a degree in the latitudinal direction. To reduce computation, 13 and 17 levels are used as standards respectively. When the digital terrain database is divided into 13 levels, the terrain data block contains M terrain data sub-blocks; when the digital terrain database is divided into 17 levels, it is equivalent to each terrain data sub-block being divided into 16 equal parts in both the longitude and latitude directions, that is, one terrain data sub-block contains 256 grids.

[0016] Furthermore,

[0017] Three different polar coordinates are established, with the aircraft's current position coordinates O, the boundary point M on the forward-looking prediction alarm envelope, and the lower boundary point Q of the alarm as poles, and a ray drawn along the aircraft's heading direction as the polar axis.

[0018] The spherical coordinates of the boundary points of each terrain data sub-block are converted into polar coordinates in three polar coordinate systems. Assume the spherical coordinates of the aircraft's current position are O(lon). o ,lat oTaking the polar coordinates of the aircraft's current position O as the pole as an example, for any point R(lon) in the plane... R ,lat R Perform coordinate transformation; the transformed coordinates are: The conversion method is as follows. LAT represents the actual distance on a meridian, where a 1-degree difference in latitude corresponds to approximately LAT meters; LON represents the actual distance difference on a latitude line, where a 1-degree difference in longitude corresponds to LON meters; θ represents the aircraft's current heading.

[0019]

[0020]

[0021] Given the spherical coordinates of the aircraft's current position, and Then the spherical coordinates of M are The spherical coordinates of point N are: The same method can be used to transform the spherical coordinates of R to polar coordinates with points M and Q as poles respectively.

[0022] In polar coordinates with point Q as the pole, determine whether the polar angles of the four boundary points of each terrain data sub-block are less than 0. If they are less than 0, it means that the terrain data sub-block is not within the forward look prediction alarm envelope, so delete the terrain data sub-block; if they are greater than 0, it means that the terrain data sub-block is within the forward look prediction alarm envelope, so save the terrain data sub-block.

[0023] In polar coordinates with point M as the pole, determine whether the polar angles of the four boundary points of each terrain data sub-block are greater than 0. If they are greater than 0, it means that the terrain data sub-block is not within the forward look prediction alarm envelope, so delete the terrain data sub-block; if they are less than 0, it means that the terrain data sub-block is within the forward look prediction alarm envelope, so save the terrain data sub-block.

[0024] In polar coordinates with O as the pole, determine whether the absolute value of the polar angle of the four boundary points of each terrain data sub-block is greater than 90 degrees, and whether the projection of the polar radius in the heading direction is greater than the forward look-ahead detection range (LAD). If the above conditions are met, it means that the terrain data sub-block is not within the forward look-ahead prediction alarm envelope, and the terrain data sub-block is deleted; if the conditions are not met, it means that the terrain data sub-block is within the forward look-ahead prediction alarm envelope, and the terrain data sub-block is saved.

[0025] Extract the maximum elevation data from the saved terrain data sub-blocks and calculate the minimum value of the forward-looking prediction alarm envelope. If the maximum elevation data is less than the minimum value of the forward-looking prediction alarm envelope, no terrain data sub-block can trigger an alarm; if the maximum elevation data is greater than the minimum value of the forward-looking prediction alarm envelope, further gridding processing is performed on the saved terrain data sub-blocks.

[0026] Furthermore,

[0027] The saved terrain data sub-blocks were extracted according to the 17-layer division method of the digital terrain database, that is, the terrain data sub-blocks were divided into grids.

[0028] The spherical coordinates of each grid in the saved terrain data sub-block are transformed into polar coordinates with point O as the pole, and the polar coordinates corresponding to the four vertices of each grid are calculated.

[0029] Determine whether at least one of the four vertices of each grid satisfies the following three conditions:

[0030] ①

[0031] ②

[0032] ③

[0033] Where D is the wing width;

[0034] If the condition is not met, it means the grid is not within the forward-looking prediction alarm envelope, so the grid is deleted; if the condition is met, it means the grid is within the forward-looking prediction alarm envelope, so the grid is saved.

[0035] Furthermore,

[0036] Determine if the elevation data of the grid is greater than the height of the corresponding forward-looking prediction alarm envelope. If it is, the grid will trigger an alarm.

[0037] Method for calculating the height of the forward-looking prediction alarm envelope corresponding to the grid:

[0038] For any grid T, its coordinates in the polar coordinate system with point O as the pole are: The height of the forward prediction alarm envelope corresponding to the grid is H. T LAD 下 HP represents the forward-looking detection range during the descent phase of the forward-looking prediction warning envelope; HC represents the aircraft's current absolute pressure altitude; and γ represents the safe altitude of the forward-looking prediction warning envelope. c Represents the inclination angle of the flight path; θ max Represents the maximum climb angle;

[0039] when hour

[0040]

[0041] when hour

[0042]

[0043] Furthermore,

[0044] When a grid intrudes into the forward-looking prediction alarm envelope, i.e., when the grid elevation data is higher than the corresponding forward-looking prediction alarm envelope, the system generates an alarm: broadcasts the "terrain" alarm voice message, displays the "terrain" alarm character, and prompts the flight crew that there is a risk of ground collision ahead.

[0045] The advantages of this invention include:

[0046] This forward-looking prediction alarm implementation method can meet the requirements of aircraft with different characteristics and different forward-looking prediction alarm envelopes, and has wide applicability.

[0047] Another advantage of the present invention includes:

[0048] This method provides an enhanced ground proximity warning system with a warning method for the entire flight process of the aircraft. Attached Figure Description

[0049] Figure 1 This is a top view of the forward-looking predictive alarm envelope.

[0050] Figure 2 This is a cross-sectional view of the envelope of the forward-looking prediction alarm.

[0051] Figure 3 This is a schematic diagram of the terrain data block extraction method.

[0052] Figure 4 This is a schematic diagram of the method for dividing terrain data into sub-block grids.

[0053] Figure 5 This is a flowchart of the method of the present invention. Detailed Implementation

[0054] This invention provides a method for implementing forward-looking prediction alarms. The method first establishes a forward-looking prediction alarm envelope, and then provides terrain data blocks in a terrain database based on the forward-looking prediction alarm envelope and the aircraft's current position. The digital terrain database is stored in a hierarchical manner; when the terrain database is divided into 13 levels, the terrain database is divided into 2... 13 Each terrain data sub-block contains a certain number of terrain data sub-blocks. It determines whether each terrain data sub-block is within the forward look-ahead prediction alarm envelope, and saves those that are. When the terrain database is divided into 17 levels, a grid is extracted, with each terrain data sub-block containing 256 grids. It checks whether the grid elevation data in the saved terrain data sub-blocks is greater than the height corresponding to the forward look-ahead prediction alarm envelope. If the grid elevation data is greater than the height corresponding to the forward look-ahead prediction alarm envelope, an alarm is triggered, including both voice and character alarms.

[0055] refer to Figure 1Top view of the forward-looking prediction warning envelope. D represents the detection width of the forward-looking prediction warning envelope, which is equal to the width of the aircraft wing; LAD represents the forward detection distance of the forward-looking prediction warning envelope, LAD = ground speed × (pilot's reaction time + maneuver pull-up time + climb time).

[0056] refer to Figure 2 Forward-looking prediction warning envelope profile. HC represents the aircraft's reserved safe altitude; γ c θ represents the aircraft's flight path inclination angle. max Represents the aircraft's maximum climb angle; t 下 t represents the time it takes for the aircraft to descend; 上 H represents the time it takes for the aircraft to climb; 下 H represents the downward distance of the descent segment; 上 LAD represents the upward distance of the ascending segment; 下 Represents the forward-looking detection range during the descent phase; LAD 上 This represents the forward-looking detection distance during the ascending and descending phase;

[0057]

[0058] t 下 = Pilot's reaction time + Maneuvering pull-up time

[0059] t 上 =Aircraft climb time

[0060] H 下 = Ground speed·t 下 ·tanγ c

[0061] H 上 = Ground speed·t 上 ·tanθ max

[0062] LAD 下 = Ground speed·t 下

[0063] LAD 上 = Ground speed·t 上

[0064] refer to Figure 3 Schematic diagram of terrain data block extraction method. Where ABCD represents the extracted terrain data blocks. MQPN represents the top view of the forward look-ahead prediction alarm envelope; θ represents the aircraft's current heading; point O is the aircraft's current position; where... The radius of the circle is R.

[0065] refer to Figure 4: Schematic diagram of terrain data sub-block gridding method. Where ABCD represents terrain data blocks. ①②③… represent terrain data sub-blocks, which are extracted from the digital terrain database after being divided into 13 levels. A'B'C'D' represent grids, which are extracted from the digital terrain database after being divided into 17 levels. Each terrain data sub-block is divided into 16 equal parts in both the longitude and latitude directions, meaning each terrain data sub-block contains 256 grids.

[0066] refer to Figure 5 : Flowchart of the method of the present invention

[0067] According to box 5-1, the forward-looking prediction warning envelope of the enhanced ground proximity warning system is calculated based on the aircraft's ground speed, heading, track inclination, maximum climb angle, wingspan, pilot's reserved reaction time, maneuver pull-up time, and climb time.

[0068] According to boxes 5-2 and 5-3, the digital terrain database is scanned based on the forward-looking detection distance (LAD) envelope and the aircraft's position information, and a terrain data block is extracted. According to the hierarchical storage method of the digital terrain database, when the digital terrain database is divided into 13 layers, the terrain data block is divided into terrain data sub-blocks with a certain amount of data.

[0069] According to box 5-4, three different polar coordinate systems are established, with the aircraft's current position coordinates O, the boundary point M on the forward-looking prediction alarm envelope, and the lower boundary point Q of the alarm as poles, and a ray drawn along the aircraft's heading as the polar axis. The spherical coordinates of the four vertices of each terrain data sub-block are then converted into polar coordinates in the three different polar coordinate systems.

[0070] According to box 5-5, in polar coordinates with point Q as the pole, determine whether the polar angles of the four boundary points of each terrain data sub-block are less than 0. If they are less than 0, it means that the terrain data sub-block is not within the forward look prediction alarm envelope, so delete the terrain data sub-block; if they are greater than 0, it means that the terrain data sub-block is within the forward look prediction alarm envelope, so save the terrain data sub-block.

[0071] In polar coordinates with point M as the pole, determine whether the polar angles of the four boundary points of each terrain data sub-block are greater than 0. If they are greater than 0, it means that the terrain data sub-block is not within the forward look prediction alarm envelope, so delete the terrain data sub-block; if they are less than 0, it means that the terrain data sub-block is within the forward look prediction alarm envelope, so save the terrain data sub-block.

[0072] In polar coordinates with O as the pole, determine whether the absolute value of the polar angle of the four boundary points of each terrain data sub-block is greater than 90 degrees, and whether the projection of the polar radius in the heading direction is greater than the forward look-ahead detection range (LAD). If the above conditions are met, it means that the terrain data sub-block is not within the forward look-ahead prediction alarm envelope, and the terrain data sub-block is deleted; if the conditions are not met, it means that the terrain data sub-block is within the forward look-ahead prediction alarm envelope, and the terrain data sub-block is saved.

[0073] Based on boxes 5-6, 5-7, and 5-8, extract the maximum elevation data from the terrain data sub-blocks and calculate the minimum value of the forward-looking prediction alarm envelope. If the maximum elevation data is less than the minimum value of the forward-looking prediction alarm envelope, no terrain data sub-block can trigger an alarm; if the maximum elevation data is greater than the minimum value of the forward-looking prediction alarm envelope, further gridding processing is performed on the saved terrain data sub-blocks.

[0074] According to 5-9, the saved terrain data sub-blocks are extracted according to the 17-layer division method of the digital terrain database, that is, the terrain data sub-blocks are divided into grids, that is, each terrain data sub-block contains 256 grids.

[0075] Based on 5-10 and 5-11, the spherical coordinates of each grid in the saved terrain data sub-block are transformed into polar coordinates with point O as the pole, and the polar coordinates corresponding to the four vertices of each grid are calculated.

[0076] Determine whether at least one of the four vertices of each grid satisfies the following three conditions:

[0077] ①

[0078] ②

[0079] ③ Where D is the wing width;

[0080] If the condition is not met, it means the grid is not within the forward-looking prediction alarm envelope, so the grid is deleted; if the condition is met, it means the grid is within the forward-looking prediction alarm envelope, so the grid is saved.

[0081] Based on 5-12 and 5-13, calculate the height corresponding to the forward prediction alarm envelope of the grid, and determine whether the elevation data of the grid is greater than the corresponding forward prediction alarm envelope height. If it is greater, the grid triggers an alarm.

[0082] According to 5-14, when a grid intrudes into the forward-looking prediction alarm envelope, i.e. the grid elevation data is higher than the corresponding forward-looking prediction alarm envelope, the system generates an alarm: broadcasts the "terrain" alarm voice, displays the "terrain" alarm character, and prompts the flight crew that there is a risk of ground collision ahead.

[0083] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for implementing forward-looking predictive alarm in an enhanced ground proximity alarm system, characterized in that, It includes the following steps, Step S1: Determine the forward-looking prediction alarm envelope; Step S2: Scan the digital terrain database based on the forward-looking detection distance (LAD) and aircraft position information in the forward-looking prediction alarm envelope, extract terrain data blocks, extract terrain data sub-blocks and grids according to the hierarchical storage method of the digital terrain database, and sequentially determine whether the terrain data sub-blocks and grids are within the forward-looking prediction alarm envelope. Step S3: Extract the elevation data of the grid within the forward prediction alarm envelope and compare it with the height of the forward prediction alarm envelope to perform a collision avoidance assessment. as well as, Step S4: If the elevation data of the grid is greater than the height of the corresponding forward prediction alarm envelope, then an alarm is executed, and the alarm is a voice and / or character alarm. Step S3 includes, Step S31: Determine whether each terrain data sub-block is within the forward prediction alarm envelope, and save the terrain data sub-blocks within the forward prediction alarm envelope; Step S32: Determine whether each grid in the saved terrain data sub-block is within the forward prediction alarm envelope; grids within the forward prediction alarm envelope will be saved. as well as, Step S33: Determine whether the elevation data of the saved grid is greater than the corresponding forward prediction alarm envelope height. If it is greater, the grid triggers an alarm. In step S31, Step S311: Using the aircraft's current position coordinates O, the boundary point M on the forward-looking prediction alarm envelope, and the lower boundary point Q of the alarm as poles, draw a ray along the aircraft's heading direction as the polar axis to establish three different polar coordinates. Step S312: Convert the spherical coordinates of the boundary points of each terrain data sub-block into polar coordinates in three polar coordinate systems; Step S313: In polar coordinates with point Q as the pole, determine whether the polar angles of the four boundary points of each terrain data sub-block are less than 0. If they are less than 0, delete the terrain data sub-block; if they are greater than 0, save the terrain data sub-block. In polar coordinates with point M as the pole, determine whether the polar angles of the four boundary points of each terrain data sub-block are greater than 0. If they are greater than 0, delete the terrain data sub-block; if they are less than 0, save the terrain data sub-block. In polar coordinates with O as the pole, determine whether the absolute value of the polar angle of the four boundary points of each terrain data sub-block is greater than 90 degrees, and whether the projection of the polar radius in the heading direction is greater than the forward sight distance (LAD). If the above conditions are met, delete the terrain data sub-block; otherwise, save the terrain data sub-block. Step S314: Extract the maximum elevation data from the saved terrain data sub-blocks and calculate the minimum value of the forward prediction alarm envelope. If the maximum elevation data is less than the minimum value of the forward prediction alarm envelope, no terrain data sub-block will trigger an alarm; if the maximum elevation data is greater than the minimum value of the forward prediction alarm envelope, the saved terrain data sub-blocks will be gridded.

2. The method for implementing forward-looking predictive alarm in an enhanced near-ground alarm system according to claim 1, characterized in that, Step S1 includes, Step S11: Calculate the forward look-ahead detection range (LAD) of the forward look-ahead prediction warning envelope based on the aircraft's ground speed, pilot's reserved reaction time, maneuver pull-up time, and climb time; determine the detection width (D) of the forward look-ahead prediction warning envelope based on the aircraft's wing width. Step S12: Calculate the descent distance H of the forward-looking prediction warning envelope based on the aircraft's flight path tilt angle. 下 The upward distance H of the ascending segment of the forward-looking prediction warning envelope is calculated based on the aircraft's maximum climb angle. 上 ; as well as, Step S13, the forward-looking prediction alarm envelope includes a downward safety height H. c .

3. The method for implementing forward-looking predictive alarm in an enhanced near-ground alarm system according to claim 1, characterized in that, In step S32, Step S321: Extract the saved terrain data sub-blocks according to the 17-layer division method of the digital terrain database, that is, perform grid extraction on the terrain data sub-blocks; Step S322: Convert the spherical coordinates of each grid in the saved terrain data sub-block into polar coordinates with point O as the pole, and calculate the polar coordinates corresponding to the four vertices of each grid. Step S323: Determine whether at least one of the four vertices of each grid satisfies the following three conditions: Where D is the wing width; If the condition is not met, it means the grid is not within the forward-looking prediction alarm envelope, so the grid is deleted; if the condition is met, it means the grid is within the forward-looking prediction alarm envelope, so the grid is saved.

4. The method for implementing forward-looking predictive alarm in an enhanced near-ground alarm system according to claim 1, characterized in that, Step S4 includes, When a grid intrudes into the forward-looking prediction alarm envelope, i.e. the grid elevation data height is higher than the corresponding forward-looking prediction alarm envelope, the system generates an alarm: broadcasts the "terrain" alarm voice, displays the "terrain" alarm character, and prompts the flight crew that there is a risk of ground collision ahead.

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