Virtual calculation and monitoring method and system for glide slope deviation signal in landing system
Patent Information
- Application Number
- PCT/CN2024/115094
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-03-04
- Filing Date
- 2024-08-28
- Publication Date
- 2025-10-02
AI Technical Summary
In the existing instrument landing system, the glide path deviation signal is easily interfered with and causes errors, which cannot meet the safety and reliability requirements of automatic landing. In particular, when the instrument landing system fails, it cannot provide a reliable glide path deviation signal.
By performing Kalman filtering fusion on INS and GPS data, a virtual glide slope deviation signal is generated and compared with the deviation signal output by the ILS system to monitor anomalies in real time. The virtual deviation signal is calculated using trigonometric functions to achieve virtual synthesis and anomaly monitoring of the glide slope deviation signal.
The safety and reliability of the automatic landing system have been improved, ensuring that a reliable glide path deviation signal can be provided when the instrument landing system fails, thereby improving flight safety and stability.
Smart Images
Figure CN2024115094_02102025_PF_FP_ABST
Abstract
Description
Virtual calculation and monitoring method and system for glide path deviation signal of landing system Technical Field
[0001] The present application relates to the field of automatic landing for civil aircraft, and specifically to a scheme for virtual synthesis and abnormality monitoring of glide path deviation signals of an instrument landing system. Background Art
[0002] Mainstream models of modern civil aircraft are equipped with automatic landing functions, which usually use the localizer deviation signal and glide path deviation signal (i.e., Gs signal or Gs deviation signal) issued by the instrument landing system (ILS).
[0003] The instrument landing system operates at low altitude during the approach and landing phase. Airborne equipment is susceptible to interference from obstacles, terrain, and other aircraft, which can cause abnormal localizer and glide path deviation signals. Guided by these erroneous deviation signals, the aircraft will deviate from its ideal glide path, compromising landing safety.
[0004] For example, a fail-safe autoland system in Category III weather conditions requires the instrument landing system to remain operational after a single failure. However, due to the limited availability of a single onboard receiving antenna for calculating the glide path deviation signal, the system cannot meet this fail-safe safety requirement. Therefore, it is necessary to develop a method for calculating a virtual glide path deviation signal to improve the safety and reliability of the autoland system.
[0005] In response to the above problems, some existing technologies have begun to address them.
[0006] Patent document CN108021137B, entitled "Flight Control System with Synthetic Glide Path (Glide Slope) Deviation and Method of Use," calculates the glide path deviation based on inertial unit data and uses a fixed threshold of 200 feet to initialize the glide path deviation using the original ILS glide path deviation. A median selector is used to select a glide path deviation for use by the autoland system from two filtered ILS glide path deviations and the calculated glide path deviation.
[0007] However, there are two problems with this prior art:
[0008] a) Using the original ILS glide path deviation to initialize the inertial glide path deviation may result in an erroneous Gs signal used for initialization, which may lead to an erroneous inertial Gs deviation signal.
[0009] b) A median selector is used to select a glide slope deviation from the two filtered ILS glide slope deviations and the calculated inertial glide slope deviation for use by the automatic landing system. When the Gs radio signal is interfered with, the glide slope deviation signals output by both ILS receivers are incorrect, and the median selector cannot obtain the correct signal.
[0010] Patent document CN 114283625A, entitled "Method for using a multiple approach guidance system to provide higher integrity with improved performance and availability," filters the ILS-based flight path deviation signal and the GNSS-based flight path deviation signal separately, introduces a scaling factor so that the two sets of filtered deviation signals are normalized to the same scale, and then combines the two normalized sets of filtered deviation signals to obtain a mixed signal, which is compared with a threshold level to detect whether there is an integrity problem and issue an alarm.
[0011] However, this prior art also has the problem that when the mixed signal is inconsistent with the threshold, it is impossible to confirm which signal (the flight path deviation signal based on ILS and the flight path deviation signal based on GNSS) is wrong, resulting in the automatic flight system having no available Gs signal.
[0012] Therefore, there is a need to provide a solution for monitoring the abnormality of the glide path deviation signal of the instrument landing system.
[0013] Summary of the Invention
[0014] The present application relates to a method and system for virtual synthesis and abnormal monitoring of a glide path deviation signal of an instrument landing system, which can monitor the abnormality of a Gs glide path deviation signal in real time and provide a virtual synthesized glide path deviation signal to improve flight safety.
[0015] According to a first aspect of the present application, a method for virtual synthesis and abnormality monitoring of a glide path deviation signal of an instrument landing system is provided, comprising:
[0016] receiving a radio signal from an airport GS station through an ILS system and generating a corresponding GS glide slope deviation signal based on the radio signal;
[0017] Virtual Gs signal calculation stage:
[0018] Input the latitude, longitude and altitude data output by the INS system and the satellite positioning system into the Kalman filter to obtain the latitude, longitude and altitude data fused by the Kalman filter;
[0019] Calculate the distance between the aircraft and the airport Gs station based on the aircraft position, the latitude and longitude coordinates of the airport Gs station, and the aircraft altitude;
[0020] Calculating a virtual synthetic glide slope deviation signal using trigonometric functions based on the distance information;
[0021] Abnormal monitoring / judgment stage:
[0022] Compare the virtual synthesized glide slope deviation signal with the Gs glide slope deviation signal to determine whether the difference between the two exceeds a preset threshold:
[0023] If the difference does not exceed the preset threshold, determining that the Gs glide slope deviation signal output by the ILS system is normal and selecting the Gs glide slope deviation signal for landing guidance;
[0024] If the difference exceeds the preset threshold, it is determined that the Gs glide slope deviation signal output by the ILS system is abnormal and the virtual synthesized glide slope deviation signal is selected for landing guidance.
[0025] According to a second aspect of the present application, a virtual synthesis and abnormality monitoring system for a glide slope deviation signal of an instrument landing system is provided, comprising: an apparatus for executing the virtual synthesis and abnormality monitoring method for a glide slope deviation signal of an instrument landing system as described in the first aspect.
[0026] This Summary is provided to introduce some concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to illustrate the manner in which the above-described and other advantages and features of the present application can be obtained, a more particular description of the present application, which has been briefly described above, will be presented by reference to specific embodiments of the present application that are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the present application and are therefore not to be considered limiting of its scope, the present application will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:
[0028] FIG1 shows an exemplary flow chart of a method for virtual synthesis and abnormality monitoring of a glide slope deviation signal of an instrument landing system according to an embodiment of the present application.
[0029] FIG2 shows a schematic three-dimensional position relationship diagram of an aircraft and an airport Gs station according to an embodiment of the present application.
[0030] A schematic structural diagram of a glide slope deviation signal virtual synthesis system for an instrument landing system according to a first embodiment of the present application. DETAILED DESCRIPTION
[0031] To address the issue of erroneous or lost glide path guidance signals during instrument landing, this application provides a solution for abnormal monitoring and virtual synthesis of glide path deviation signals during the instrument landing phase of an aircraft. This solution monitors the glide path deviation signal in real time during the instrument landing phase and promptly isolates the faulty signal. Furthermore, an effective fusion algorithm is designed to fuse data from various onboard sensors, synthesizing a virtual glide path guidance signal in abnormal situations. This signal is then provided to the automatic landing control system as input, improving landing safety.
[0032] FIG1 shows an exemplary flow chart of a method for virtual synthesis and abnormality monitoring of a glide slope deviation signal of an instrument landing system according to an embodiment of the present application.
[0033] For ease of explanation and understanding, this flowchart describes virtual GS signal synthesis based on INS / GPS Kalman fusion. INS stands for the airborne inertial navigation system, and GPS stands for the global navigation satellite system. However, it should be understood that the GPS in this example can be replaced with other satellite positioning systems such as Beidou and Galileo, and will not be further elaborated here.
[0034] When the aircraft captures the ILS Gs signal, virtual synthesis calculation and abnormality detection are started. The following describes the method of virtual synthesis and abnormality monitoring of the ILS glide path deviation signal with reference to the schematic flow chart shown in FIG1 .
[0035] First, the virtual Gs signal calculation stage 110 is performed. In this stage, the INS and GPS signals are used as input signals and fused through the Kalman filter to obtain fused latitude, longitude and altitude data. Then, through geometric transformation and solving trigonometric functions, the fused latitude, longitude and altitude signals output by the Kalman filter are used to generate a virtual synthetic glide slope deviation signal. In the following example, the virtual synthetic glide slope deviation signal is based on the glide slope angle Y G_Kalman Take this as an example to illustrate.
[0036] Specifically, in step 112, the latitude, longitude, and altitude data output by the INS and GPS systems are used as two input signals for the Kalman filter. After receiving the two input signals from the INS and GPS, the Kalman filter fuses these two signals (combined navigation solution), thereby obtaining the latitude, longitude, and altitude data fused by the Kalman filter. Since Kalman filtering is common knowledge in the field of integrated navigation, this step will not be described in detail here.
[0037] Subsequently, in step 114, the distance information between the aircraft and the Gs station is calculated based on the aircraft position, the latitude and longitude coordinates of the airport Gs station, and the aircraft altitude, including but not limited to the relative distance between the projection point of the aircraft on the runway surface and the Gs station, or the straight-line distance from the projection point of the aircraft on the ground to the Gs station, and the projection distance on the runway centerline, etc.
[0038] The distance calculation can be explained as follows in conjunction with the three-dimensional positional relationship between the aircraft and the airport Gs station shown in FIG2 :
[0039] In Figure 2, the actual position of the aircraft and the projection of the aircraft on the vertical plane where the runway centerline is located are marked. B is the standard glide angle (determined by the airport's Gs ground equipment, generally between 2° and 4°, and normally 3°), D LOC D is the straight-line distance between the projection point of the aircraft on the ground and the LOC station. Z is the vertical distance from the projection point of the aircraft on the ground to the centerline of the runway, H is the height of the aircraft from the ground. In this solution, H can be the height output by the onboard atmospheric system, the radio altitude, or the height calculated based on the DME ranging value. L is the straight-line distance from the projection point of the aircraft on the ground to the Gs station, and the projection distance on the centerline of the runway. D GS It is the straight-line distance between the projection point of the aircraft on the ground and the Gs station.
[0040] The aircraft's latitude and longitude coordinates can be obtained from the fused latitude, longitude, and altitude data, while the latitude and longitude coordinates of the GPS station can be directly obtained using a positioning device such as GPS. The other parameters in Figure 2 can be obtained directly from sensor measurements or derived from geometric conversion relationships of known parameters.
[0041] Then, in step 116, a virtual synthetic glide slope angle Y is calculated based on the distance information using trigonometric functions. G_Kalman .
[0042] Specifically, from the geometric relationship diagram of the aircraft landing process shown in Figure 2, the glide slope angle γ can be obtained G The calculation expression is:
[0043] In the formula (1), D Z It can be obtained by the side offset calculation formula, which is as follows:
[0044] Where the Earth's semi-major axis R c =6378137.0m, Earth ellipticity E D =0.0033523, a is the latitude of the aircraft, Where k1 is the celestial component of the localizer position converted to geocentric latitude in the Earth coordinate system, k0 is the celestial component of the runway centerline threshold starting point converted to geocentric latitude in the Earth coordinate system, and k is the celestial component of the aircraft location converted to geocentric latitude in the Earth coordinate system. The specific formula is:
[0045] Among them, L is the longitude of the aircraft's location, L0 is the longitude of the starting point on the runway centerline, L1 is the longitude of the localizer, and B EC is the geocentric latitude of the aircraft’s location, B EC0 is the geocentric latitude corresponding to the starting point on the runway centerline, B EC1 is the geocentric latitude of the localizer position, and its calculation process is as follows:
[0046] Among them, the Earth's major axis R c =6378137.0m, Earth's semi-minor axis R d =6356752.0m, B is the latitude of the aircraft, B o is the latitude of the starting point on the runway centerline, B1 is the latitude of the localizer, and H is the altitude of the aircraft.
[0047] In the formula (1), D GS The distance between two points can be obtained by the longitude and latitude conversion formula, which is as follows:
[0048] in, Δy=R p ·(B EC -B ECGS ), where the meanings of the variables are the same as in the previous formula, B GS is the latitude of the airport Gs station, L GS is the longitude of the airport Gs station, B ECGS is the geocentric latitude of the airport Gs station.
[0049] Through the above calculation process, the virtual synthetic glide slope angle γ can be calculated. G_Kalman, and its unit is degree. At the same time, according to the unified requirements of international civil aviation regulations for the accuracy and resolution of the Gs signal emitted by the instrument landing system, the deviation signal represented by the angle has a proportional relationship with the current signal (in microamperes) and the modulation depth difference signal (DDM) emitted by the airborne Gs receiver. Therefore, it can be considered that the glide slope angle, current signal, and DDM have equivalent meanings. Therefore, technical personnel can easily understand that in addition to using the glide slope angle as a glide path deviation signal, it is also possible to use equivalent current signals, DDM and other signals as glide path deviation signals for abnormal monitoring. The above-mentioned example of the glide slope angle is given for illustrative purposes only, and is not intended to limit the scope of protection of this application to the glide slope angle.
[0050] When executing the steps of the virtual Gs signal calculation phase 110, in step 120, the system also receives a radio signal from the airport Gs station via the ILS system and generates a corresponding Gs glide slope deviation signal based on the signal. Since the glide slope angle is used as the glide slope deviation signal in the above example, the ILS-Gs glide slope angle γ is generated based on the signal received by the ILS system. G_ILS The process of generating the Gs glide slope deviation signal is a common technical means of the landing guidance system, and therefore, it will not be described here.
[0051] After generating the virtual synthetic glide slope angle γ G _ Kalman and ILS-Gs glide path angle γ G_ILS Afterwards, the process enters the abnormality monitoring / judgment stage 130 .
[0052] In the abnormal monitoring / judgment stage 130, the virtual synthetic glide slope deviation signal (in this example, the glide slope angle Y) output by the Kalman filter is G_Kalman ) is used as a reference virtual synthetic signal and is compared with the Gs glide slope deviation signal output by the ILS system (in this example, the ILS-Gs glide slope angle γ G_ILS ) to determine whether the ILS signal is abnormal. If the ILS signal is normal (i.e., the difference between the glide path deviation signal output by the ILS system and the virtual synthesized glide path deviation signal does not exceed the preset threshold Z), the Gs glide path deviation signal output by the ILS is selected for landing guidance. If the difference between the glide path deviation signal output by the ILS system and the virtual synthesized glide path deviation signal continuously exceeds the preset threshold Z, an abnormality alarm signal (e.g., an abnormality flag of FaultFLag = 1) is output, and the aircraft's landing guidance signal is switched to the virtual synthesized glide path deviation signal output by the Kalman filter, thereby isolating the abnormal ILS system's Gs glide path deviation signal.
[0053] Specifically, as shown in FIG1 , in step 110, the virtual synthetic glide slope angle γ is calculated. G_Kalman , and in step 120 obtain the ILS-Gs glide path angle γ G_ILS Afterwards, the process enters the abnormality monitoring / judgment stage 130 .
[0054] First, at step 132, the virtual synthetic glide slope angle γ G_Kalman Glide slope angle γ with ILS-Gs G_ILS A comparison is made to determine whether the difference between the two exceeds a preset threshold Z.
[0055] If the ILS-Gs glide path angle γ output by the ILS system G_ILS The virtual composite glide slope angle γ G_Kalman If the difference between the ILS signal and the Gs signal does not exceed the preset threshold Z, it is determined that the ILS signal is not abnormal, and the process proceeds to step 134, where the ILS-Gs glide path angle γ output by the ILS is selected. G_ILS Serves as a landing guidance signal.
[0056] If the ILS-Gs glide path angle γ output by the ILS system G_ILS The virtual composite glide slope angle γ G_Kalman If the difference between the two exceeds the preset threshold Z, it is determined that the ILS signal is abnormal, and the process enters step 136, where the virtual synthetic glide slope angle γ is selected. G_Kalman Serves as a landing guidance signal.
[0057] Considering the smooth transition between signal switching between different source signals to eliminate the impact of accuracy differences on the control system, the ILS system's glide path deviation signal is typically only considered abnormal when the difference between multiple (e.g., m) consecutive sampling points exceeds a threshold value, Z. At this point, the landing guidance signal is switched to a virtual synthesized glide path deviation signal, and a visual or audible warning is issued to the pilot. In other words, if only a few consecutive sampling points have a difference exceeding threshold value Z, it is generally not considered an abnormality. This avoids frequent switching of landing guidance signals and ensures the stability of landing guidance.
[0058] In a preferred embodiment, a glide signal healing mechanism (i.e., glide signal healing stage 140) can be additionally introduced based on the above process. If the result of the judgment in process 132 is that the ILS signal is abnormal, in addition to entering step 136 to set the virtual synthetic glide angle γ G_Kalman In addition to the landing guidance signal, the process also enters the descent signal healing phase 140 .
[0059] Specifically, in the glide path signal healing stage 140, first, in step 142, the virtually generated glide path deviation signal (e.g., the virtually synthesized glide path angle γ) at a plurality of subsequent consecutive sampling points (e.g., n) is continuously determined. G_Kalman ) and the glide path deviation signal output by the ILS system (e.g. ILS-Gs glide path angle γ G_ILS ) do not exceed the preset threshold Z.
[0060] If the difference does not exceed the preset threshold value Z, it can be determined that the ILS system signal has returned to normal. Therefore, the process can return to step 134, in which the landing guidance signal is switched back to the glide slope deviation signal output by the ILS system.
[0061] If the difference still exceeds the preset threshold Z value, it means that the ISL system signal has not returned to normal and is still in an abnormal state. At this time, the process can return to step 136 to continue selecting the virtual synthetic glide slope deviation signal as the landing guidance signal.
[0062] It should be understood that the preset threshold Z, m sampling points, and n sampling points mentioned in the above process are not fixed. In the above embodiment, the preset threshold Z can be set to 0.1 degrees, which is affected by the true value of the Gs signal and the distribution of abnormal Gs signals during aircraft landing. The number of sampling points m and n can be set to 3. The specific setting of the threshold and the number of sampling points requires statistical analysis based on a large amount of experimental data to determine acceptable values that meet monitoring requirements.
[0063] It should be understood that in order to facilitate the pilot to understand the status change of the landing guidance signal, a visual or auditory warning indication may be sent to the pilot each time the landing guidance signal is switched.
[0064] Furthermore, considering that civil aircraft navigation systems are typically equipped with two ILS systems, the average of the two ILS glidepath deviation signals can be compared with the virtual composite glidepath deviation signal to achieve a difference threshold. If signal interference causes an abnormal ILS glidepath deviation signal, it is generally assumed that both ILS systems will be affected. Therefore, according to the aforementioned anomaly detection logic flow, the landing guidance signal is switched to the virtual composite glidepath deviation signal.
[0065] Innovations of this application:
[0066] 1) A virtual synthesis algorithm for the glide path deviation signal for instrument landing is proposed. The virtual synthetic Gs is calculated using the aircraft position parameters after Kalman filtering, avoiding the use of erroneous original Gs signals to initialize the virtual calculation process, which would affect the calculation process.
[0067] 2) By comparing the signals from two different sources, the interference situation of the airport radio Gs signal can be monitored in real time.
[0068] 3) A monitoring scheme for abnormal glide path guidance signals during instrument landing is proposed, and a glide path guidance signal healing mechanism is introduced to achieve dynamic monitoring and automatic repair of the glide path guidance signals.
[0069] Although various embodiments have been described above, it should be understood that they are intended to be illustrative only and not limiting. Persons skilled in the relevant art(s) will appreciate that various modifications may be made in form and detail without departing from the spirit and scope of the present application as defined by the appended claims. Therefore, the breadth and scope of the present application as disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined only in accordance with the appended claims and their equivalents.
Claims
1. A method for virtual synthesis and abnormality monitoring of a glide path deviation signal of an instrument landing system, comprising: receiving a radio signal from an airport GS station through an ILS system and generating a corresponding GS glide slope deviation signal based on the radio signal; Virtual Gs signal calculation stage: Input the latitude, longitude and altitude data output by the INS system and the satellite positioning system into the Kalman filter to obtain the latitude, longitude and altitude data fused by the Kalman filter; Calculate the distance between the aircraft and the airport Gs station based on the aircraft position, the latitude and longitude coordinates of the airport Gs station, and the aircraft altitude; Calculating a virtual synthetic glide slope deviation signal using trigonometric functions based on the distance information; Abnormal monitoring / judgment stage: Compare the virtual synthesized glide slope deviation signal with the Gs glide slope deviation signal to determine whether the difference between the two exceeds a preset threshold: If the difference does not exceed the preset threshold, selecting the Gs glide slope deviation signal for landing guidance; If the difference exceeds the preset threshold, the Gs glide slope deviation signal is determined to be abnormal, and the virtual synthesized glide slope deviation signal is selected for landing guidance.
2. The virtual synthesis and abnormality monitoring method according to claim 1, characterized in that: The step of comparing the virtual synthesized glide slope deviation signal with the Gs glide slope deviation signal to determine whether a difference between the two exceeds a preset threshold is performed for a plurality of consecutive sampling points, and the landing guidance signal is switched to the virtual synthesized glide slope deviation signal only when the comparison differences at the plurality of consecutive sampling points all exceed the threshold.
3. The virtual synthesis and abnormality monitoring method according to claim 2, characterized in that: When it is determined that the Gs glide slope deviation signal output by the ILS system is abnormal, the virtual synthesis and abnormality monitoring method further includes: Downward signal healing stage: a step of comparing the virtual synthesized glide slope deviation signal with the Gs glide slope deviation signal for a plurality of subsequent consecutive sampling points to determine whether the difference between the two exceeds a preset threshold, and Only when the comparison difference of the subsequent multiple consecutive sampling points does not exceed the threshold, the The land guidance signal switches back to the Gs glide slope deviation signal output by the ILS system.
4. The virtual synthesis and abnormality monitoring method according to claim 1, wherein: The Gs glide slope deviation signal output by the ILS system is the ILS-Gs glide slope angle, and the virtual synthetic glide slope deviation signal is the virtual synthetic glide slope angle.
5. The virtual synthesis and abnormality monitoring method according to claim 1, wherein: The GS glide slope deviation signal output by the ILS system is a current signal or a modulation depth difference signal DDM sent by an airborne GS receiver, and the virtual synthesized GS glide slope deviation signal is a corresponding virtual synthesized current signal or modulation depth difference signal DDM.
6. The virtual synthesis and abnormality monitoring method according to claim 2, characterized in that: Also includes: A visual or audible warning indication is given to the pilot each time a landing guidance signal is switched.
7. The virtual synthesis and abnormality monitoring method according to claim 1, wherein: When the aircraft navigation system is equipped with two ILS systems, taking the average of the Gs glide slope deviation signals output by the two ILS systems and comparing it with the virtual synthesized glide slope deviation signal; If it is determined that the Gs glide slope deviation signal output by the ILS system is abnormal, it is determined that both of the two ILS systems are affected, and the virtual synthesized glide slope deviation signal is selected for landing guidance.
8. A virtual synthesis and abnormality monitoring system for a glide path deviation signal of an instrument landing system, comprising: An apparatus for executing the method for virtual synthesis and abnormality monitoring of a glide slope deviation signal of an instrument landing system according to any one of claims 1 to 7.