Method for suppressing false alarms of excessive terrain closure rate alarms in ground proximity warning systems

Abstract

The present invention provides a method for suppressing false alarms of excessive terrain closing rate alarms of a ground proximity warning system, comprising the following steps: step 1, acquiring multi-source avionics data, and calculating a terrain closing rate TCR0 based on radio height; step 2, selecting a corresponding warning envelope according to a flap state, and judging whether TCR0 enters the warning envelope range; step 3, when TCR0 enters the warning envelope range, calculating a terrain closing rate TCR1 based on a terrain database; when TCR0 does not enter the warning envelope range, repeating step 1; step 4, calculating the absolute value of the difference between TCR0 and TCR1, and issuing an alarm when the absolute value is less than or equal to a tolerance value; and calculating a fused terrain closing rate TCRmix of TCR0 and TCR1 when the absolute value is greater than the tolerance value; step 5, issuing an alarm when TCRmix enters the warning envelope range; and executing step 1 when TCRmix does not enter the warning envelope range.

Description

Technical Field

[0001] The present invention relates to the field of radar technology, and in particular to a method for suppressing false alarms of excessive terrain closure rate alarms of a ground proximity warning system. Background Art

[0002] The excessive terrain closure rate warning of the ground proximity warning system is also called the mode 2 warning. According to the configuration of the flaps, it can be divided into two types of warnings: 2A and 2B. Each warning corresponds to a different envelope.

[0003] The typical Mode 2 warning logic mainly uses the radio altitude provided by the radio altimeter (LRRA) and the flap status information provided by the digital stall warning computer (DSWC) to calculate whether the combination of the current radio altitude and the terrain closure rate is within the warning envelope. The degree of harm caused by the parameter intrusion into the envelope determines whether to issue a warning message to the pilot. The terrain closure rate refers to the rate of change of the radio altitude within a certain period of time.

[0004] The calculation method based on the time differential of radio altitude has certain limitations. Specifically, it is easily affected by factors such as flight status and sudden changes in terrain, which may cause Mode 2 false alarms. Summary of the Invention

[0005] In view of this, an embodiment of the present specification provides a method for suppressing false alarms of excessive terrain closure rate alarms in a ground proximity warning system, so as to achieve the purpose of improving the alarm confidence of the device.

[0006] The embodiments of this specification provide the following technical solution: a method for suppressing false alarms of excessive terrain closure rate alarms in a ground proximity warning system, comprising the following steps:

[0007] Step 1: Obtain multi-source avionics data and calculate the terrain closure rate TCR0 based on radio height;

[0008] Step 2: Select the corresponding warning envelope based on the flap status and determine whether the terrain closure rate TCR0 based on the radio height enters the warning envelope range;

[0009] Step 3: When the terrain closure rate based on radio altitude (TCR0) enters the alert envelope, obtain the rectangular area in front of the aircraft nose based on the airspeed, predicted time, and required navigation performance (RNP). Read the terrain altitude value from the terrain database for the rectangular area. Use the difference between the pressure altitude and the terrain altitude as a substitute for the radio altitude to calculate the terrain closure rate based on the terrain database (TCR1). If the terrain closure rate based on radio altitude (TCR0) does not enter the alert envelope, repeat step 1.

[0010] Step 4: Calculate the absolute value of the difference between the terrain closing rate TCR0 based on the radio height and the terrain closing rate TCR1 based on the terrain database. When the absolute value is less than or equal to the tolerance value, issue an alarm. When the absolute value is greater than the tolerance value, calculate the fused terrain closing rate TCRmix of the terrain closing rate TCR0 based on the radio height and the terrain closing rate TCR1 based on the terrain database.

[0011] Step 5: When the fused terrain close rate TCRmix enters the alarm envelope, an alarm is issued. If the fused terrain close rate TCRmix does not enter the alarm envelope, execute step 1.

[0012] Furthermore, step one includes:

[0013] Step 1.1: Collect aircraft and flight status data from multi-source avionics data;

[0014] Step 1.2: Based on the recorded radio altitude, Calculate and obtain the terrain closure rate TCR0 based on the radio altitude;

[0015] Furthermore, step 2 includes:

[0016] Step 2.1. Select the envelope range to be calculated based on the aircraft configuration.

[0017] Step 2.2: Compare the terrain closure rate (TCR0) based on radio altitude with the radio altitude value and the envelope range to determine whether the value is within the envelope range.

[0018] Furthermore, step three includes: when the terrain closure rate (TCR0) based on radio altitude enters the warning envelope range, extracting terrain information from the terrain database, calculating the terrain selection offset based on the required navigation performance (RNP), determining the terrain range ahead based on the airspeed, calculating the terrain elevation data within the range, and forming a terrain relief curve in the current flight direction; and calculating the terrain closure rate (TCR1) based on the terrain database using the aircraft's current pressure altitude and the terrain elevation.

[0019] Furthermore, step three is specifically as follows:

[0020] Step 3.1, calculate the location block number based on the current coordinates of the aircraft, and then extract the terrain database file of the location block number;

[0021] Step 3.2: According to Range=V air ·t calc Determine the terrain processing range, where Range represents the range, V air represents airspeed, t calcIndicates the predicted time; with the aircraft's current coordinates as the origin and the heading direction as the vertical axis, the terrain elevation is processed into a semicircular horizontal projection view according to the range;

[0022] Step 3.3, calculate the distance width offset calculation value of the left and right ends of the current aircraft's localizer by d = k·RNP, where k is a constant factor with a value range of (0,1]; combined with the range calculated in step 3.2, determine that the terrain processing data range is a rectangle with a 2d length as the base and a range length as the height; divide the rectangle height evenly into small rectangular blocks of the same size according to the terrain resolution, traverse and calculate the maximum elevation value in each rectangular block, and form the terrain elevation trend of a certain distance in front of the aircraft; according to the formula Calculate the terrain closure rate TCR1 based on the terrain database;

[0023] Furthermore, step four is specifically as follows:

[0024] Step 4.1: Based on the terrain closure rates calculated in steps 1.2 and 3.3, determine whether to issue an alarm using the formula |TCR1-TCR0|<err. If the absolute value of the difference between the two calculated results is less than or equal to the tolerance, an alarm is generated; otherwise, proceed to step 4.2.

[0025] Step 4.2: According to the flight trajectory of the aircraft, the false alarm shift calculation constant N is established by the formula: When N is not an integer, round up is used;

[0026] Step 4.3, refer to the false alarm calculation constant, move forward N sampling points from the current moment of the aircraft, calculate the mean square error σ of the two terrain closing rates, and determine the confidence level f of the terrain database processing result terr (σ).

[0027] Step 4.4: From step 4.3, the false alarm impact factor of the current aircraft track point is 1-f terr (σ), the fused terrain closing rate TCRmix is ​​obtained through weighted fusion, and it is judged whether the fused terrain closing rate TCRmix and the radio altitude are within the warning envelope.

[0028] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least the following: the present invention improves the alarm performance indicators by optimizing the design logic of the system, thereby achieving the purpose of improving the alarm confidence of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0030] Figure 1 It is a schematic diagram of the process structure of an embodiment of the present invention;

[0031] Figure 2 This is a diagram of the false alarm suppression function architecture of the terrain perception and warning system mode 2 of the present invention;

[0032] Figure 3 It is a schematic diagram of terrain elevation processing based on terrain database. DETAILED DESCRIPTION

[0033] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0034] The following describes the embodiments 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 embodiments, 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 features in the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0035] like Figures 1 to 3 As shown, an embodiment of the present invention provides a method for suppressing false alarms of excessive terrain closure rate alarms in a ground proximity warning system, comprising the following steps:

[0036] Step 1: Obtain multi-source avionics data and calculate the terrain closure rate TCR0 based on radio height;

[0037] Step 2: Select the corresponding warning envelope based on the flap status and determine whether the terrain closure rate TCR0 based on the radio height enters the warning envelope range;

[0038] Step 3: When the terrain closure rate based on radio altitude (TCR0) enters the alert envelope, obtain the rectangular area in front of the aircraft nose based on the airspeed, predicted time, and required navigation performance (RNP). Read the terrain altitude value from the terrain database for the rectangular area. Use the difference between the pressure altitude and the terrain altitude as a substitute for the radio altitude to calculate the terrain closure rate based on the terrain database (TCR1). If the terrain closure rate based on radio altitude (TCR0) does not enter the alert envelope, repeat step 1.

[0039] Step 4: Calculate the absolute value of the difference between the terrain closing rate TCR0 based on the radio height and the terrain closing rate TCR1 based on the terrain database. When the absolute value is less than or equal to the tolerance value, issue an alarm. When the absolute value is greater than the tolerance value, calculate the fused terrain closing rate TCRmix of the terrain closing rate TCR0 based on the radio height and the terrain closing rate TCR1 based on the terrain database.

[0040] Step 5: When the fused terrain close rate TCRmix enters the alarm envelope, an alarm is issued. If the fused terrain close rate TCRmix does not enter the alarm envelope, execute step 1.

[0041] Furthermore, step one includes:

[0042] Step 1.1: Collect aircraft and flight status data from multiple avionics sources for calculation in subsequent steps, including latitude and longitude from GPS, altitude, heading, three-axis body speed from IRU, radio altitude from LLRA, RNP from FMS, airspeed from ADC, and flap status from DSWC;

[0043] Step 1.2: Based on the recorded radio altitude, calculate using formula (1) to obtain the terrain closure rate value based on radio altitude;

[0044]

[0045] Furthermore, step 2 includes:

[0046] Step 2.1. Select the calculated envelope range based on the aircraft configuration, mainly the flap status. When the flaps are retracted, select mode 2A envelope; otherwise, select mode 2B.

[0047] Step 2.2: Based on the terrain closure rate calculated in step 1.2, combined with the radio altitude value, it is compared with the envelope range to determine the preliminary warning result. If it is in the warning area, the following calculation steps are performed; otherwise, the current position point is skipped and the next solution cycle is entered.

[0048] Step 3: Extract terrain information from the terrain database and calculate the terrain selection offset based on the required navigation performance (RNP). Determine the terrain range ahead based on the airspeed and calculate the terrain elevation data within the range to form a terrain curve for the current flight direction. Calculate the terrain closure rate (TCR1) based on the terrain database using the aircraft's current pressure altitude and terrain elevation.

[0049] Furthermore, step three includes:

[0050] Step 3.1, calculate the location block number based on the current coordinates of the aircraft, and then extract the terrain database file of the location block number;

[0051] Step 3.2: Determine the terrain processing range according to formula (2), where V air represents airspeed, t calc Indicates the predicted time; then, with the aircraft's current coordinates as the origin and the heading direction as the vertical axis, the terrain elevation is processed into a semicircular horizontal projection view according to the range;

[0052] Range=V air ·t calc (2)

[0053] d=k·RNP (3)

[0054] Step 3.3: Calculate the distance width offset calculation value of the left and right ends of the current aircraft's localizer path using formula (3), where k is a constant factor with a value range of (0,1]. The RNP (Required Navigation Performance) is sent to TAWS by the flight management system FMS. Combined with the range calculated in step 3.2, determine the terrain processing data range, that is, a rectangle with a 2d length as the base and a range length as the height. Divide the rectangle into small rectangular blocks of the same size according to the terrain resolution, and traverse and calculate the maximum elevation value in each rectangular block to form the terrain elevation trend of a certain distance in front of the aircraft. Then, calculate the terrain closure rate TCR1 based on the terrain database using the formula.

[0055]

[0056] Step 4: Compare the terrain approach rates calculated twice in different ways. If the absolute value of the difference between the two calculation results is less than the tolerance, an alarm is generated. Otherwise, the false alarm impact factor is calculated. The terrain approach rate is fused by the false alarm impact factor to determine whether the combined parameter is within the alarm envelope range. If it is not in the alarm area, no alarm is generated at this time. Otherwise, an alarm is generated.

[0057] Step 4.1: Based on the terrain closure rate calculated in steps 1.2 and 3.3, determine whether to issue an alarm using formula (5). If the absolute value of the difference between the two calculation results is less than the tolerance, a mode 2 alarm is generated; otherwise, proceed to step 4.2.

[0058] |TCR1-TCR0| <err (5)

[0059] Step 4.2: According to the aircraft's flight trajectory (level flight or descent), establish the false alarm shift calculation constant N. The calculation process is shown in formula (6).

[0060]

[0061] If N is not an integer, it is rounded up. When the aircraft's descent rate is less than 100 fpm, the aircraft is assumed to be in level flight, and N can be 20. When the descent rate exceeds 1000 fpm, the descent rate is considered excessive, an emergency situation, and a rapid response is required. At other times, the value changes linearly with the descent rate.

[0062] Step 4.3, refer to the false alarm calculation constant, move forward N sampling points from the current moment of the aircraft, calculate the mean square error σ of the two terrain closing rates, and determine the confidence level f of the terrain database processing result terr (σ), the specific definition is determined by the supplier.

[0063] Step 4.4: From step 4.3, the false alarm impact factor of the current aircraft track point is 1-f terr (σ), the terrain closing rate is obtained through weighted fusion, and it is judged whether the fused terrain closing rate and radio altitude are within the warning envelope. If they are within the warning range, an alarm is generated; otherwise, no alarm is generated.

[0064] TCR mix =(1-f terr (σ))·TCR0+f terr (σ)·TCR1 (7)

[0065] Beneficial effects of the embodiments of the present invention:

[0066] Low dependency and easy to implement. The technical method adopted by the present invention can realize the algorithm by itself without increasing the number of interconnected devices. The intermediate quantities used (such as terrain database) are pre-stored in the system and no external source input is required, so the implementation difficulty is relatively low.

[0067] Improve equipment performance and optimize functional configuration. Currently, in the TAWS logical architecture, Mode 2 functionality is suppressed when Forward Terrain Alert (FLTA) is enabled, indicating that Mode 2 has a smaller protection margin and is underutilized. Reducing the Mode 2 false alarm rate allows both FLTA and Mode 2 alert functions to be enabled simultaneously, optimizing system functional configuration.

[0068] Redundant checksum and high reliability. The use of a terrain database greatly enhances TAWS's ability to perceive the terrain ahead. This method uses two methods, one based on the terrain database and the other based on radio altitude, to calculate the terrain closure rate and compare them. Finally, the new terrain closure rate is calculated by fusing the two methods, significantly improving the confidence of the calculation results.

[0069] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences from other embodiments. In particular, the method embodiments described later are relatively simple to describe because they correspond to the system. For relevant parts, refer to the description of the system embodiments.

[0070] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for suppressing false alarms of excessive terrain closure rate alarms in a ground proximity warning system, characterized in that: The following steps are involved: Step 1: Obtain multi-source avionics data and calculate the terrain closure rate TCR0 based on radio height; Step 2: Select the corresponding warning envelope based on the flap status and determine whether the terrain closure rate TCR0 based on the radio height enters the warning envelope range; Step 3: When the terrain closure rate (TCR0) based on radio altitude enters the warning envelope, the rectangular area in front of the nose is obtained based on the airspeed, predicted time, and required navigation performance (RNP). The terrain altitude value in the terrain database for the rectangular area is read. The difference between the pressure altitude and the terrain altitude is used as a substitute for the radio altitude to calculate the terrain closure rate (TCR1) based on the terrain database. When the terrain closing rate TCR0 based on radio high does not enter the warning envelope range, repeating step 1; Step 4: Calculate the absolute value of the difference between the terrain closing rate TCR0 based on the radio height and the terrain closing rate TCR1 based on the terrain database. When the absolute value is less than or equal to the tolerance value, issue an alarm. When the absolute value is greater than the tolerance value, calculate the fused terrain closing rate TCRmix of the terrain closing rate TCR0 based on the radio height and the terrain closing rate TCR1 based on the terrain database. Step 5: When the fused terrain close rate TCRmix enters the warning envelope range, an alarm is issued. When the fused terrain close rate TCRmix does not enter the warning envelope range, execute step 1; The step one comprises: Step 1.1: Collect aircraft and flight status data from multi-source avionics data; Step 1.2: Based on the recorded radio altitude, Calculate and obtain the terrain closure rate TCR0 based on the radio altitude; The second step includes: Step 2.

1. Select the envelope range to be calculated based on the aircraft configuration. Step 2.2: Compare the terrain closure rate (TCR0) based on radio altitude with the radio altitude value and the envelope range to determine whether the value is within the envelope range. Step three includes: when the terrain closure rate (TCR0) based on the radio altitude enters the warning envelope, extracting terrain information from the terrain database, calculating a terrain selection offset based on the required navigation performance (RNP), determining the terrain range ahead based on the airspeed, calculating the terrain elevation data within the range, and forming a terrain relief curve for the current flight direction; and calculating the terrain closure rate (TCR1) based on the terrain database using the aircraft's current pressure altitude and the terrain elevation. The step three is specifically as follows: Step 3.1, calculate the location block number based on the current coordinates of the aircraft, and then extract the terrain database file of the location block number; Step 3.2, according to Determine the range of terrain processing, where Range represents the range. Indicates airspeed, Indicates the predicted time; with the aircraft's current coordinates as the origin and the heading direction as the vertical axis, the terrain elevation is processed into a semicircular horizontal projection view according to the range; Step 3.3, by Calculate the distance width offset calculation value of the left and right ends of the current aircraft's localizer, where k is a constant factor with a value range of (0,1]; combined with the range calculated in step 3.2, determine that the terrain processing data range is a rectangle with a 2d length as the base and a Range length as the height; divide the rectangle into small rectangular blocks of the same size according to the terrain resolution, traverse and calculate the maximum elevation value in each rectangular block, and form the terrain elevation trend of a certain distance in front of the aircraft; according to the formula Calculate the terrain closure rate TCR1 based on the terrain database; The step 4 is specifically as follows: Step 4.1: Based on the terrain closure rate calculated in steps 1.2 and 3.3, the formula Determine whether to issue an alarm. If the absolute value of the difference between the two calculation results is less than or equal to the tolerance, an alarm is generated; otherwise, go to step 4.

2. Step 4.2: According to the flight trajectory of the aircraft, the false alarm shift calculation constant N is established by the formula: , where N is rounded up when it is not an integer; Step 4.3, refer to the false alarm calculation constant, move forward N sampling points from the current moment of the aircraft, calculate the mean square error σ of the two terrain closing rates, and determine the confidence level of the terrain database processing result ; Step 4.4: From step 4.3, the false alarm impact factor of the current aircraft track point is: , the fused terrain close rate TCRmix is ​​obtained through weighted fusion, and it is judged whether the fused terrain close rate TCRmix and the radio altitude are within the warning envelope.

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