Irs / dme / loc integrated navigation method and integrated navigation terminal for civil aircraft

Abstract

The application discloses an IRS / DME / LOC combined navigation method and a combined navigation terminal for a civil aircraft. k The IRS position is calibrated to obtain the aircraft position, and k=k+1 is set to jump to the first step for iteration; the application fuses navigation information output by an inertial reference system (IRS), ranging information output by a distance measuring equipment (DME) and a LOC modulation depth difference (DDM) output by an instrument landing system (ILS), and provides continuous and accurate positioning information for the aircraft in the approach phase of the aircraft.

Description

Technical Field

[0001] This invention relates to the field of civil aviation technology, specifically to an IRS / DME / LOC integrated navigation method and integrated navigation terminal for civil aircraft. Background Technology

[0002] Both domestic and international civil aviation sectors are promoting the operation of performance-based navigation (PBN), which requires the aircraft's area navigation (RNAV) system to provide real-time and continuous positioning and guidance functions.

[0003] Currently, the RNAV system of civil aircraft typically fuses navigation data from Global Navigation Satellite System (GNSS), Inertial Reference System (IRS, also known as Inertial Navigation System), Very High Frequency Omnidirectional Beacon (VOR), and Distance Measuring Equipment (DME) to calculate the aircraft's position. However, during the aircraft's approach phase, GNSS signals are easily interfered with in the near-ground region, VOR signals have poor availability at low altitudes, and it is difficult to find two DME navigation stations with suitable geometry for DME / DME positioning, thus affecting the continuity of RNAV functionality.

[0004] The Localizing Beacon (LOC) and Distance Measuring Equipment (DME) signals provided by the Instrument Landing System (ILS) offer high accuracy, availability, continuity, and integrity as navigation sources. Fusing these signals with navigation data from the Inertial Reference System (IRS) allows the RNAV system to calculate precise positions. While some advanced transport aircraft abroad offer LOC / DME navigation, their underlying mechanisms, particularly the methods for fusing them with IRS navigation data, have not been publicly disclosed.

[0005] The ground system of the Instrument Landing System (ILS) consists of a Localizer (LOC) station located at the end of the runway, and a Glide Slope Beacon (GS) station and Distance Measuring Equipment (DME) station located at the runway threshold. Figure 1 As shown, Chengdu Shuangliu International Airport has two runways and a total of four ILS systems are deployed, two for each runway. Aircraft can choose any runway and approach from either end using the corresponding ILS system. The ILS ground system with the identification code ICR is used by aircraft approaching from south to north (02R) on the second runway. Its GS and DME stations are located next to the south end of the runway, and the LOC station is located on the outer extension line at the north end of the runway.

[0006] The aircraft's ILS equipment receives the LOC and GS signals and calculates the depth of modulation (DDM) difference between the 90Hz and 150Hz modulated waves to indicate the aircraft's deviation from the expected approach path in both the horizontal and vertical directions. The DME equipment measures and outputs the slant distance between the aircraft and the DME station.

[0007] According to the current Instrument Flight Rules (IFR) for ILS / DME approach procedures, the ranging information from the airborne DME transponder is typically used in conjunction with the aircraft altitude information measured by the radio altimeter (PA) to determine the aircraft's deviation from the expected approach path in the vertical profile. Therefore, current applications merely use DME ranging information as a substitute for the pointing beacon (MB) signal, without fully exploring its potential in radio positioning applications. Summary of the Invention

[0008] The technical problem to be solved by this invention is that current application methods only use DME ranging information as a substitute for the pointing beacon (MB) signal, without exploring its potential in radio positioning applications. The purpose is to provide an IRS / DME / LOC integrated navigation method and integrated navigation terminal for civil aircraft, which solves the problems of poor availability of VOR / DME, DME / DME and other land-based positioning methods and GNSS positioning, as well as the problem of low accuracy of pure inertial navigation positioning.

[0009] This invention is achieved through the following technical solution:

[0010] An IRS / DME / LOC integrated navigation method for civil aircraft, characterized in that it includes:

[0011] The first step is to calculate the state transition matrix at time k. Measurement matrix Measurement vector State equation noise covariance matrix Measurement noise covariance matrix State equation noise driving matrix ;

[0012] The second step is to establish an IRS / DME / LOC integrated navigation filter model and input the data at time k-1 into the integrated navigation filter model.

[0013] The third step is to obtain the predicted state vector. , ,in Let k be the state vector at time k-1;

[0014] The fourth step is to obtain the predicted state covariance matrix. , ,in, Let be the state covariance matrix at time k-1. Let K be the noise covariance matrix of the state equation at time k-1. The noise driving matrix is ​​the state equation.

[0015] Step 5: Calculate the gain matrix , ,in Let k be the measurement matrix at time k. Let be the measurement noise covariance matrix at time k;

[0016] Step 6: Update the state matrix , ,in, Let k be the measurement vector at time k;

[0017] Step 7: Update the covariance matrix , ,in, It is the identity matrix;

[0018] Step 8, using the state matrix The IRS position is calibrated to obtain the aircraft position, and after setting k=k+1, the process jumps to the first step for iteration.

[0019] Furthermore, before using the IRS / DME / LOC integrated navigation, it is necessary to determine whether the activation conditions for integrated navigation are met. If not, integrated navigation will not be used; if so, integrated navigation will be used.

[0020] The following three startup conditions must be met simultaneously:

[0021] Condition 1: Obtain the data required for integrated navigation from the navigation database. The data required for integrated navigation includes the longitude of the localizer, the latitude of the localizer, the heading of the localizer, the latitude of the glide slope, the longitude of the glide slope, the elevation of the glide slope, the width of the localizer, and the magnetic declination.

[0022] Condition 2: Both the ILS equipment and the DME equipment are tuned to the operating frequency of the ILS ground navigation station used for the approach and output stable navigation measurement data.

[0023] Condition 3: The aircraft has acquired the locale, and the modulation depth difference (DDM) of the LOC signal measurement is ≤0.155.

[0024] Specifically, an IRS / DME / LOC integrated navigation filtering model is established, which includes state equations and measurement equations.

[0025] The state equation characterizes the relationship between the state vector at time k and the state vector at time k-1: ,in The noise vector of the state equation at time k-1. The noise driving matrix is ​​the state equation.

[0026] The measurement equation characterizes the relationship between the measurement vector and the state vector: ,in For measuring noise.

[0027] Specifically, the noise driving matrix of the state equation The equation for obtaining: ,in, The noise driving matrix is ​​the state equation of the IRS. It is a second-order identity matrix;

[0028] State transition matrix The equation for obtaining: ,in, Here is the state transition matrix of the IRS. It is a 2×2 all-zero matrix;

[0029] The noise vector of the state equation at time k The equation for obtaining: ,in, The noise vector is the state equation of the IRS. The noise vector of the state equation of the ILS. To measure the slant distance error of DME equipment, The error is calculated for the LOC signal DDM of the ILS device;

[0030] The state equation and noise covariance matrix at time k The equation for obtaining: ,in, The noise covariance matrix is ​​the state equation of the IRS. Follows zero mean and variance The normal distribution Follows zero mean and variance It follows a normal distribution.

[0031] Optionally, The calculation formula is: Where D is the slope distance measured by DME;

[0032] The calculation formula is: ,in, The standard deviation of the signal error. The theoretical value of the LOC signal DDM calculated for the ILS device.

[0033] Specifically, measurement matrix The methods for obtaining it include:

[0034] At the output location of the IRS Perform a first-order Taylor expansion. ,in, , The latitude and longitude of the IRS output location. The latitude and longitude of the DME station;

[0035] At the output location of the IRS Perform a first-order Taylor expansion. ,in, , ;

[0036] Combining the two Taylor expansions above, we obtain the measurement matrix: ,in, and These are the radii of curvature of the WGS-84 Earth reference ellipsoid at the location of the DME station, specifically the meridian and trochoidal radii. For the width of the course, It is a 1×6 all-zero matrix. It is a 1×11 all-zero matrix.

[0037] Specifically, the equation for obtaining the noise measurement is as follows: , The sum of the noise measured for DME equipment and the noise introduced by neglecting higher-order terms of the Taylor expansion. The sum of the noise measured for the ILS device and the noise introduced by neglecting the higher-order terms of the Taylor expansion;

[0038] Measurement noise covariance matrix: .

[0039] Optionally, and The methods for obtaining it include:

[0040] Determine the latitude and longitude of the DME station. Determine the latitude and longitude of LOC station Heading route Course width Magnetic declination Obtain the latitude and longitude of the aircraft ;

[0041] Calculate the theoretical value of the slope distance for DME equipment measurement ,in, and These are the radii of curvature of the meridional and trochoidal circles of the WGS-84 Earth reference ellipsoid at the location of the DME station, respectively.

[0042] Calculate the azimuth angle of the IRS location relative to the LOC station: ;

[0043] Calculate the aircraft's deviation angle relative to the heading: ;

[0044] Calculate the theoretical DDM value of the LOC signal calculated by the ILS device. ;

[0045] calculate , .

[0046] Specifically, through the state matrix Methods for calibrating IRS positions to obtain aircraft positions include:

[0047] from Extract and through The IRS location was calibrated, and the calibrated IRS location is as follows: .

[0048] An IRS / DME / LOC integrated navigation terminal for civil aircraft includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described above.

[0049] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0050] This invention provides continuous and accurate positioning information for the aircraft during the approach phase by fusing navigation information output by the inertial reference system (IRS), ranging information output by the distance measuring instrument (DME), and the localizer (LOC) modulation depth difference (DDM) output by the instrument landing system (ILS). Attached Figure Description

[0051] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0052] Figure 1 This is a schematic diagram of the instrument landing system layout for two runways according to the present invention.

[0053] Figure 2 This is a schematic flowchart of the IRS / DME / LOC integrated navigation method for civil aircraft according to the present invention.

[0054] Figure 3 This is a schematic diagram illustrating the calculation of the aircraft's deviation angle relative to the course according to the present invention. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0056] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0057] Where there is no conflict, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0058] Example 1

[0059] This embodiment provides a combined navigation method that fuses navigation information output by the inertial reference system (IRS), ranging information output by the distance measuring instrument (DME), and the localizer (LOC) modulation depth difference (DDM) output by the instrument landing system (ILS) based on a Kalman filter model, providing continuous and accurate positioning information for the aircraft during the approach phase.

[0060] This application is based on the Kalman filter model, and therefore extends the Kalman filter model of the inertial reference system (IRS) to obtain the Kalman filter model of the IRS / DME / LOC integrated navigation:

[0061] Establish an IRS / DME / LOC integrated navigation filter model, which includes state equations and measurement equations;

[0062] The state equation characterizes the relationship between the state vector at time k and the state vector at time k-1: ,in The noise vector of the state equation at time k-1. The noise driving matrix is ​​the state equation.

[0063] The measurement equation characterizes the relationship between the measurement vector and the state vector: ,in For measuring noise.

[0064] There are various forms of IRS Kalman filter models; this embodiment uses the most common 18-dimensional state model.

[0065] The IRS state vector based on the IRS Kalman filter model is ,in, These represent the attitude error in the northeast-sky direction. These represent the velocity errors in the northeast-sky direction. These represent the positioning errors of latitude and longitude, These represent the constant drift of the gyroscope. The noise in the stochastic state equation of a first-order Markov process for a gyroscope is represented by the following: These are the first-order Markov constant drifts of the accelerometer;

[0066] The noise vector in the IRS state equation based on the IRS Kalman filter model is... ,in, These represent the first-order Markov process error of the gyroscope. These represent the noise in the white state equation of the gyroscope's angular rate. These are the white state equation noises of the accelerometer.

[0067] like Figure 2 As shown, this embodiment provides an IRS / DME / LOC integrated navigation method for civil aircraft, characterized by comprising:

[0068] The first step is to calculate the state transition matrix at time k. Measurement matrix Measurement vector State equation noise covariance matrix Measurement noise covariance matrix State equation noise driving matrix That is, the specific parameters mentioned above are calculated using the relevant parameters at time k-1.

[0069] The second step is to establish an IRS / DME / LOC integrated navigation filter model and input the data at time k-1 into the integrated navigation filter model; through the integrated navigation filter model, in conjunction with the data calculated in the first step, the measurement vector is obtained.

[0070] The third step is to obtain the predicted state vector. , ,in Let k be the state vector at time k-1;

[0071] The fourth step is to obtain the predicted state covariance matrix. , ,in, Let be the state covariance matrix at time k-1. Let K be the noise covariance matrix of the state equation at time k-1. The noise driving matrix is ​​the state equation.

[0072] Step 5: Calculate the gain matrix , ,in Let k be the measurement matrix at time k. Let be the measurement noise covariance matrix at time k;

[0073] Step 6: Update the state matrix , ,in, Let k be the measurement vector at time k;

[0074] Step 7: Update the covariance matrix , ,in, It is the identity matrix;

[0075] Step 8, using the state matrix The IRS position is calibrated to obtain the aircraft position, and after setting k=k+1, the process jumps to the first step for iteration.

[0076] Through the state matrix Methods for calibrating IRS positions to obtain aircraft positions include: from Extract and through The IRS location was calibrated, and the calibrated IRS location is as follows: .

[0077] Example 3

[0078] This embodiment explains the calculation of the matrix parameters mentioned in Embodiment 2.

[0079] The state vector is formed by concatenating the state vector XIRS of the inertial navigation system and two state variables of the instrument landing system (including DME and LOC). ,in Let k be the state vector of the IRS at time k. The state vector of the ILS. The ranging error of the DME equipment, The LOC signal DDM measurement error of the ILS device.

[0080] When the system is fault-free, the DDM output from the ILS device and the slant range output from the DME device are independent and uncorrelated in time; therefore, the state transition matrix... The equation for obtaining: ,in, Here is the state transition matrix of the IRS. It is a 2×2 all-zero matrix.

[0081] The noise vector of the state equation at time k The equation for obtaining: ,in, The noise vector is the state equation of the IRS. The noise vector of the state equation of the ILS. To measure the slant distance error of DME equipment, The error is calculated for the LOC signal DDM of the ILS device; when the system is fault-free, Follows zero mean and variance The normal distribution Follows zero mean and variance It follows a normal distribution.

[0082] According to the RTCA DO-236C standard, the variance of the ranging error of the DME The calculation formula is: (nautical miles), where D is the DME slant distance (nautical miles).

[0083] ILS measurement error variance of DDM The calculation formula is: The error consists of two parts: signal error and airborne equipment processing error. According to Annex 10, Volume I, "Radio Navigation Facilities," of the International Civil Aviation Convention, the standard deviation of signal error is [not specified] when the approach categories are Category I, II, and III. The standard deviation of the signal error is 0.008, 0.004, and 0.0025, respectively. The theoretical DDM value of the LOC signal calculated for ILS equipment. According to RTCA DO-195 standard, "Airborne Instrument Landing System Localizer Receivers Operating in the 108–112 MHz Radio Frequency Range," 95% ( The processing error of the airborne equipment shall not exceed 5% of the actual DDM.

[0084] State equation noise driving matrix The equation for obtaining: ,in, The noise driving matrix is ​​the state equation of the IRS. It is a second-order identity matrix;

[0085] The state equation and noise covariance matrix at time k The equation for obtaining: ,in, Let be the noise covariance matrix of the state equation of the IRS.

[0086] The latitude, longitude, and altitude of the DME station are known. Determine the latitude and longitude of LOC station Heading route Course width Magnetic declination Obtain the latitude and longitude of the aircraft ;

[0087] Calculate the theoretical value of the slope distance for DME equipment measurement ,in, and These are the radii of curvature of the meridional and trochoidal circles of the WGS-84 Earth reference ellipsoid at the location of the DME station, respectively. , Re = 6378137 meters is the length of the semi-major axis of the WGS-84 Earth reference ellipsoid, and e = 0.08181919084265 is the eccentricity of the WGS-84 Earth reference ellipsoid.

[0088] As shown in Figure 3, when the aircraft is located near the heading path... And when the LOC signal is intercepted, the ILS device calculates the theoretical value of the LOC signal DDM.

[0089] First, calculate the azimuth angle of the IRS position relative to the LOC station: ;

[0090] Calculate the aircraft's deviation angle relative to the heading: ;

[0091] Calculate the theoretical DDM value of the LOC signal calculated by the ILS device. ;

[0092] Measurement vectors in IRS / LOC / DME integrated navigation: ,in, Establish the slant distance from the aircraft to the DME station for the measurement output of the airborne DME. The DDM is calculated and output by the airborne ILS equipment based on the received LOC signal. To calculate the slant range of the aircraft relative to the DME station using IRS position information. The aircraft receive LOC signal DDM is calculated by the IRS using its own location information;

[0093] The slope distance measured by DME equipment can be expressed as... At the output position of the IRS Perform a first-order Taylor expansion. ,in, , The latitude and longitude of the IRS output location. The latitude and longitude of the DME station; The sum of the noise measured by the DME equipment and the noise introduced by neglecting the higher-order terms of the Taylor expansion.

[0094] The LOC signal DDM measured by the ILS device can be represented as follows: At the output position of the IRS Perform a first-order Taylor expansion. ,in, , ; The sum of the noise measured for the ILS device and the noise introduced by neglecting the higher-order terms of the Taylor expansion.

[0095] Combining the two Taylor expansions above, we obtain the measurement matrix: ,in, and These are the radii of curvature of the WGS-84 Earth reference ellipsoid at the location of the DME station, specifically the meridian and trochoidal radii. For the width of the course, It is a 1×6 all-zero matrix. It is a 1×11 all-zero matrix.

[0096] Measurement noise covariance matrix: It can be approximated as a diagonal matrix by real-time measurement of the vector. Compared with its predicted value and The variance of the error between them is estimated to obtain: Let Then, by using the first N time steps, we can estimate... The i-th diagonal element .

[0097] Equation for obtaining the measurement noise: .

[0098] Example 3

[0099] Furthermore, before using the IRS / DME / LOC integrated navigation, it is necessary to determine whether the activation conditions for integrated navigation are met. If not, integrated navigation will not be used; if so, integrated navigation will be used.

[0100] The following three startup conditions must be met simultaneously:

[0101] Condition 1: Obtain the data required for integrated navigation from the navigation database. The data required for integrated navigation includes the longitude of the localizer, the latitude of the localizer, the heading of the localizer, the latitude of the glide slope, the longitude of the glide slope, the elevation of the glide slope, the width of the localizer, and the magnetic declination; that is, read the data shown in the table below.

[0102]

[0103] Modern commercial airliners typically use navigation databases that conform to the ARINC 424 standard. Each entry in the database is 132 bytes long and can be divided into multiple fields, with the 5th and 6th bytes being the entry type field (for example, PI and PA are the contents stored in the 5th and 6th bytes of these two types of entries in the table, respectively).

[0104] Condition 2: Both the ILS equipment and the DME equipment are tuned to the operating frequency of the ILS ground navigation station used for the approach and output stable navigation measurement data.

[0105] Condition 3: The aircraft has acquired the locale, and the modulation depth difference (DDM) of the LOC signal measurement is ≤0.155.

[0106] Example 4

[0107] An IRS / DME / LOC integrated navigation terminal for civil aircraft includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described above.

[0108] Memory is used to store software programs and modules. The processor executes various terminal functions and data processing by running the software programs and modules stored in memory. Memory can mainly include a program storage area and a data storage area. The program storage area can store the operating system, at least one executable program required for a given function, etc.

[0109] The storage data area can store data created based on the use of the terminal. Furthermore, the memory can include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory, or other volatile solid-state storage devices.

[0110] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the aforementioned IRS / DME / LOC integrated navigation method for civil aircraft.

[0111] Without loss of generality, computer-readable media can include computer storage media and communication media. Computer storage media includes volatile and non-volatile, removable and non-removable media implemented using any method or technology for storing information such as computer-readable instruction data structures, program modules, or other data. Computer storage media includes RAM, ROM, EPROM, EEPROM, flash memory or other solid-state storage technologies, CD-ROM, DVD or other optical storage, magnetic tape cassettes, magnetic tape, disk storage, or other magnetic storage devices. Of course, those skilled in the art will recognize that computer storage media are not limited to the above-mentioned types. The aforementioned system memories and mass storage devices can be collectively referred to as memory.

[0112] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0113] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0114] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A method for integrated IRS / DME / LOC navigation in civil aircraft, characterized in that, include: The first step is to calculate the state transition matrix at time k. Measurement matrix Measurement vector State equation noise covariance matrix Measurement noise covariance matrix State equation noise driving matrix ; The second step is to establish an IRS / DME / LOC integrated navigation filter model and input the data at time k-1 into the integrated navigation filter model. The third step is to obtain the predicted state vector. , ,in The state vector at time k-1; The fourth step is to obtain the predicted state covariance matrix. , ,in, Let be the state covariance matrix at time k-1. Let K be the noise covariance matrix of the state equation at time k-1. The noise driving matrix is ​​the state equation. Step 5: Calculate the gain matrix , ,in Let k be the measurement matrix at time k. Let be the measurement noise covariance matrix at time k; Step 6: Update the state matrix , ,in, Let k be the measurement vector at time k; Step 7: Update the covariance matrix , ,in, It is the identity matrix; Step 8, using the state matrix The IRS position is calibrated to obtain the aircraft position, and after setting k=k+1, the process jumps to the first step for iteration. Among them, an IRS / DME / LOC integrated navigation filter model is established, which includes state equations and measurement equations; The state equation characterizes the relationship between the state vector at time k and the state vector at time k-1: ,in The noise vector of the state equation at time k-1. The noise driving matrix of the state equation is obtained from the following equation: ,in, The noise driving matrix is ​​the state equation of the IRS. It is a second-order identity matrix; The measurement equation characterizes the relationship between the measurement vector and the state vector: ,in For measuring noise; State transition matrix The equation for obtaining: ,in, Here is the state transition matrix of the IRS. It is a 2×2 all-zero matrix; The noise vector of the state equation at time k The equation for obtaining: ,in, The noise vector is the state equation of the IRS. The noise vector of the state equation of the ILS. To measure the slant distance error of DME equipment, The error is calculated for the LOC signal DDM of the ILS device; The state equation and noise covariance matrix at time k The equation for obtaining: ,in, The noise covariance matrix is ​​the state equation of the IRS. Follows zero mean and variance The normal distribution Follows zero mean and variance It follows a normal distribution.

2. The IRS / DME / LOC integrated navigation method for civil aircraft according to claim 1, characterized in that, Before using IRS / DME / LOC combined navigation, it is necessary to determine whether the conditions for launching combined navigation are met. If not, combined navigation will not be used; if so, combined navigation will be used. The following three startup conditions must be met simultaneously: Condition 1: Obtain the data required for integrated navigation from the navigation database. The data required for integrated navigation includes the longitude of the localizer, the latitude of the localizer, the heading of the localizer, the latitude of the glide slope, the longitude of the glide slope, the elevation of the glide slope, the width of the localizer, and the magnetic declination. Condition 2: Both the ILS equipment and the DME equipment are tuned to the operating frequency of the ILS ground navigation station used for the approach and output stable navigation measurement data. Condition 3: The aircraft has acquired the locale, and the modulation depth difference (DDM) of the LOC signal measurement is ≤0.

155.

3. The IRS / DME / LOC integrated navigation method for civil aircraft according to claim 1, characterized in that, The calculation formula is: Where D is the slope distance measured by DME; The calculation formula is: ,in, The standard deviation of the signal error. The theoretical value of the LOC signal DDM calculated for the ILS device.

4. The IRS / DME / LOC integrated navigation method for civil aircraft according to claim 1, characterized in that, Measurement matrix The methods for obtaining it include: At the output location of the IRS Perform a first-order Taylor expansion. ,in, , The latitude and longitude of the output location of the IRS. The latitude and longitude of the DME station The sum of the noise measured for DME equipment and the noise introduced by neglecting higher-order terms of the Taylor expansion. To calculate the slant range of the aircraft relative to the DME station using IRS position information. Establish the slant distance from the aircraft to the DME station for the measurement output of the airborne DME; At the output location of the IRS Perform a first-order Taylor expansion. ,in, , , The sum of the noise measured by the ILS device and the noise introduced by neglecting the higher-order terms of the Taylor expansion. The DDM is calculated and output by the airborne ILS equipment based on the received LOC signal. The aircraft receive LOC signal DDM is calculated by the IRS using its own location information. The coordinates of the LOC station are latitude and longitude. Combining the two Taylor expansions above, we obtain the measurement matrix: ,in, and These are the radii of curvature of the WGS-84 Earth reference ellipsoid at the location of the DME station, specifically the meridian and trochoidal radii. For the width of the heading path, It is a 1×6 all-zero matrix. It is a 1×11 all-zero matrix.

5. The IRS / DME / LOC integrated navigation method for civil aircraft according to claim 4, characterized in that, Equation for obtaining measurement noise: ; Measurement noise covariance matrix: .

6. The IRS / DME / LOC integrated navigation method for civil aircraft according to claim 4, characterized in that, and The methods for obtaining it include: Determine the latitude and longitude of the DME station. Determine the latitude and longitude of LOC station Heading route Course width Magnetic declination Obtain the latitude and longitude of the aircraft ; Calculate the theoretical value of the slope distance for DME equipment measurement ; Calculate the azimuth angle of the IRS location relative to the LOC station: ; Calculate the aircraft's deviation angle relative to the heading: ; Calculate the theoretical DDM value of the LOC signal calculated by the ILS device. ; calculate , .

7. The IRS / DME / LOC integrated navigation method for civil aircraft according to claim 1, characterized in that, Through the state matrix Methods for calibrating IRS positions to obtain aircraft positions include: from Extract and through The IRS location was calibrated, and the calibrated IRS location is as follows: ; in, The latitude and longitude of the output location of the IRS.

8. An IRS / DME / LOC integrated navigation terminal for civil aircraft, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1-7.

Images