Take-off and landing lateral deviation error value filtering correction method based on sectional type coordinate system

Abstract

The invention relates to the field of aircraft parameter reliability identification, and relates to a segmented coordinate system-based take-off and landing lateral deviation error value filtering correction method. According to the method, the sectional airport coordinate system is adopted to continuously update the lateral deviation displacement of the unmanned aerial vehicle relative to the runway center line, the lateral deviation error cumulant can be effectively reduced, the error peak can be smoothed, the lateral deviation estimation error is kept in a tolerable range, and the high risk caused by large key parameter errors in the take-off and landing stage of the high-speed unmanned aerial vehicle is effectively relieved. And a runway lateral offset error value caused by coordinate system conversion can be effectively reduced. Effective guarantee is provided for the safety of the take-off and landing stage of the large-scale high-speed unmanned aerial vehicle, the possibility that the aircraft enters abnormal flight control logic due to false alarm caused by overlarge lateral offset error of a runway is reduced, and the method is based on telemetry data simulation verification of a real unmanned aerial vehicle.

Description

Technical Field

[0001] The invention relates to the field of aircraft parameter reliability identification, and in particular to a take-off and landing lateral deviation error value filtering correction method based on a segmented coordinate system. Background Art

[0002] High-speed unmanned aerial vehicles are becoming increasingly important in the aviation field. Compared with manned aircraft, pilots cannot directly feel the lateral offset of the aircraft relative to the centerline of the runway (with the take-off point as the origin, the other end of the runway as the positive end, and the vertical direction of the runway to the left). This offset is a key parameter for the pilot to observe the safety stage of flight takeoff and landing in the ground station, which directly affects the pilot's judgment on the current mission. At the same time, the wrong judgment of this value will cause the onboard software to automatically trigger the termination logic of the mission or enter the wrong working mode, affecting the execution of the mission and flight safety.

[0003] In the current mission environment, the differential Beidou reference equipment in the ground command and control system sends satellite navigation correction information to the aircraft in real time. The drone collects satellite navigation positioning information through the airborne satellite navigation and positioning equipment and combines the differential correction information to calculate the current corrected real-time position P (longitude, latitude, altitude) of the aircraft, and sends it to the ground command and control system through a wireless link. The ground command and control system calculates the lateral offset of the aircraft relative to the runway system through the precise coordinate information of the two end points of the runway measured in advance (the longitude and latitude information of the two end points of the available length of the runway) and the approximate conversion formula of the geographic coordinate system to the airport runway coordinate system, and updates it in real time to refresh the display to the pilot.

[0004] The approximate processing of the lateral deviation will lead to errors as the aircraft moves away from the origin of the runway coordinate system. In actual experiments, it was found that for every 3,000-meter standard civil aviation runway, the conversion formula will produce a lateral deviation error of about 3 meters. Ordinary runways are generally 50 meters wide and have a maximum lateral deviation of 25 meters. For medium and large aircraft, the control law gives a safe lateral deviation of about 7-10 meters. Considering the superposition of multiple interference factors such as the physical flatness of the runway, short-term wind speed and wind direction changes, and wind shear, the short-term lateral deviation of the aircraft may exceed 5 meters. Summary of the invention

[0005] Purpose of the Invention

[0006] In this case, the lateral deviation caused by the formula error has approached the threshold acceptable to the airborne system and the pilot. A method needs to be designed to reduce and smooth the approximate error caused by the coordinate system conversion.

[0007] Technical Solution

[0008] A filtering and correction method for take-off and landing lateral deviation error values ​​based on a segmented coordinate system. The present invention adopts a segmented airport coordinate system to continuously update the lateral deviation displacement of a UAV relative to the centerline of a runway, which can effectively reduce the accumulated lateral deviation error, smooth out the error peak, and keep the lateral deviation estimation error within a tolerable range, effectively alleviating the high risk caused by large errors in key parameters during the take-off and landing stage of a high-speed UAV.

[0009] The steps include:

[0010] Step 1: Consider the number of calibration points and the accuracy requirements of the offset to determine the number of airport segments and the points to be calibrated. For fixed airports, use satellite positioning and calibration equipment to divide the available distance of the airport runway centerline into N segments in our environment.

[0011] Step 2: Use the differential calibration equipment to obtain the longitude, latitude, and altitude position information of the point to be calibrated in advance, establish the airport coordinate system group, and obtain the runway direction information according to the runway heading approximate calculation formula. At this point, the preparatory work for calculating the aircraft's side deviation relative to the runway centerline is completed.

[0012] Step 3: During the mission, the UAV collects satellite navigation and positioning information through the onboard satellite navigation and positioning equipment and calculates the current corrected real-time position of the UAV based on the differential correction information, and sends it to the ground command and control system via a wireless link.

[0013] Step 4: According to the real-time position information of the UAV and the origin position information of the pre-calibrated runway coordinate system group, the calibrated coordinate system closest to the UAV position is selected as the current matching runway coordinate system.

[0014] Step 5: According to the approximate conversion formula Δ y =-(R+h)cos(θ)cos(L j )×δλ+(R+h)sin(θ)×δL, real-time calculation of the aircraft's lateral deviation Δ relative to the runway centerline y , where R represents the local radius of the earth without considering the eccentricity, h represents the altitude of the aircraft, θ represents the direction of the airport runway, and L j represents the latitude of calibration point j, δλ represents the longitude error of the aircraft's real-time position relative to the current calibration point, and δL represents the latitude error of the aircraft's real-time position relative to the current calibration point.

[0015] Furthermore, the purpose of step 6 is also included: providing the UAV pilot with the aircraft's lateral deviation relative to the runway centerline in real time, providing the pilot with a more accurate and intuitive aircraft position, which can be used for visual display and mission planning landing instructions.

[0016] Furthermore, before step 1, the aircraft should have the capability of real-time positioning, and the take-off and landing airport runways should be known.

[0017] Furthermore, the N segments in step 1 are specifically: if a 3000m long runway is divided into 300m segments, then N=10, and a total of 11 calibration points need to be calibrated.

[0018] Furthermore, the selection of the number of segments N in step 1 follows the following principle: the longer the runway, the more segments, and the denser the calibration points, the more frequent the offset error correction, the more suppressed the divergence, and the greater the pre-calibration workload and real-time calculation workload.

[0019] Furthermore, the establishment of the coordinate system in step 2 is specifically as follows: a total of N+1 points O need to be calibrated j The position coordinates (λ j L j h j ), where λ j O j Point longitude value, L j O j Point longitude value, h j O j The longitude value of the point. j The runway coordinate system O is established with the centerline of the runway as the coordinate origin, the X axis as the runway centerline, the aircraft passing direction as the positive direction, the vertical direction to the left of the positive X axis as the positive Y axis, and the vertical direction of the X and Y axes as the Z axis. j XYZ.

[0020] Furthermore, before step 4, the aircraft should be in the approach glide path or pass-through stage, that is, at this time there is a need to calculate the side deviation to assist the aircraft in aligning with the central axis of the target airport.

[0021] Furthermore, before step 4, the aircraft should have passed through at least one calibration point, that is, the aircraft is located in at least one positive interval of the X-axis of the calibration coordinate system, and only then is the side deviation correction performed.

[0022] Furthermore, one method of selecting the matching calibration coordinate system in step 4 is: selecting the calibration point closest to the aircraft as the current matching calibration coordinate system.

[0023] Furthermore, in step 4, the UAV will pass through runway systems 1 to N in sequence during the take-off and landing phase, and may stop on a runway system midway. The lateral displacement is calculated based on the currently matched calibrated runway system, and P(λL h) is used to represent the position coordinates of the UAV.

[0024] Furthermore, in step 5, even if the real-time position information of the UAV and the origin position information of the pre-calibrated runway coordinate system group are completely accurate, errors will still be introduced in the lateral deviation calculation due to the coordinate system conversion, which is also the suppression goal of this method.

[0025] The beneficial effects of this application are:

[0026] Simulation experiments show that this method can reduce the maximum error caused by approximate conversion to one tenth of the original error, effectively reducing the lateral offset error relative to the runway centerline during the real-time calculation of the UAV take-off and landing safety-critical stage by the ground command and control system.

[0027] It is worth mentioning that the lateral offset error can be further reduced through a denser division method, but the initial calibration workload will increase. In practical applications, the number of calibration points, airport environment, and offset accuracy requirements can be comprehensively considered to determine the number of airport segments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a flow chart of a certain implementation scheme of the segmented sideslip error correction method according to the present invention.

[0029] Figure 2 This is a schematic diagram of an airport runway model.

[0030] Figure 3 It is a simulation diagram of the algorithm based on the segmented sideslip error correction method of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail in combination with the embodiment of the present invention. In the example, the same or similar reference numerals throughout represent the same or similar originals or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of them. The embodiments described below by reference are exemplary and intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention. The following is a detailed description in combination with the embodiments of the present invention.

[0032] The present invention uses a segmented airport coordinate system to continuously update the UAV's lateral displacement. For a fixed airport, the available distance of the airport runway centerline is divided by satellite positioning calibration equipment. In our environment, it is divided into 9 segments, and a total of 10 points need to be calibrated. j The position coordinates (λ j L j h j ), where λ j O j Point longitude value, L j O j Point longitude value, h j O j The longitude value of the point.j The runway coordinate system O is established by taking the X axis as the origin and the runway centerline as the X axis. The nose direction is positive, the vertical direction to the left of the X axis is the positive direction of the Y axis, and the vertical direction of the X and Y axes is the Z axis. j XYZ.

[0033] During the take-off and landing phase, the UAV will pass through runway systems 1 to 10 in sequence (it may stop on a runway system midway), and determine in real time that the aircraft is currently located in the positive direction of the X-axis of the nearest runway system, and calculate the lateral displacement based on this runway system, using P(λLh) to represent the position coordinates of the UAV.

[0034] Ignoring the eccentricity, considering that the local earth radius is basically equal, that is, The coordinate information can be used to establish the representation of each point in the Earth-centered Earth-fixed rectangular coordinate system (ECEF system, abbreviated as e system), taking point P (λL h) as an example:

[0035]

[0036] So far, it can be expressed in latitude and longitude, the aircraft relative to a certain coordinate O j The offset of the origin is

[0037] In order to better represent the side deviation, the offset Δ j Expressed in the runway coordinate system:

[0038]

[0039] Among them, l j Department represents O j The runway coordinate system O is the origin j XYZ,n j Department represents O j The local geographic coordinate system with the origin as the origin (using the northeast right-hand coordinate system).

[0040] Usually the direction of an airport runway is fixed at θ, where θ is the angle between the runway and the geographic north.

[0041] At this point, the local geographic coordinate system n can be established j To the runway coordinate system j The transformation matrix of the system:

[0042]

[0043] Among them, the transformation matrix established at each calibration point is the same and is written uniformly as

[0044] Establish e to n series j The transformation matrix of the system:

[0045]

[0046] At this point, the real-time position of the aircraft P(λL h) and the position of the calibration point O can be expressed in the local airport coordinate system using only two points of latitude and longitude. j (λ j L j h j ) between them.

[0047] Now let δλ j =λ-λ j , δL j =LL j ,δh j =hh j .

[0048] When the aircraft P just passes the calibration point O j When δλ j , δL j ,δh j All are small quantities. At this time, high-order small quantities are ignored, and the aircraft's lateral deviation relative to the runway centerline can be simplified as:

[0049] Δ y =-(R+h)cos(θ)cos(L j )×δλ+(R+h)sin(θ)×δL

[0050] Obviously, as the distance between aircraft P and calibration point O increases, j The farther away, the following errors will be caused in the side deviation calculation:

[0051] (1) Due to δλ j , δL j ,δh j It is the inherent error of the model caused by a small number of assumptions not being true.

[0052] (2)Δ y It will itself change with δλ j , δL j increases with the increase of .

[0053] The error calculated by the segmented side deviation filtering correction method adopted by the present invention is:

[0054] Δ=Δ j , when the plane P is at O j The X axis of XYZ is positive and is aligned with O j The closest distance.

[0055] At this time, by increasing the number of calibration points, once the aircraft matches the next calibration runway system, the new calibration system origin coordinate value is used as the observation input to correct the sideways error and avoid δλ j , δLj ,δh j The random volume position increases indefinitely to maintain the accuracy of the model.

[0056] See also Figure 1 , Figure 1 The figure is a flow chart of a certain implementation scheme of the segmented sideslip error correction method according to the present invention.

[0057] It should be particularly noted that the segmented sideslip error correction method described in this embodiment may include but is not limited to the following steps.

[0058] Step 1: Consider the number of calibration points, airport environment, and offset accuracy requirements to determine the number of airport segments and the points to be calibrated.

[0059] Step 2: Use the differential calibration equipment to obtain the longitude, latitude, and altitude position information of the point to be calibrated in advance, establish the airport coordinate system group, and obtain the runway direction information according to the runway heading approximate calculation formula. At this point, the preparatory work for calculating the aircraft's side deviation relative to the runway centerline is completed.

[0060] Step 3: During the mission, the UAV collects satellite navigation and positioning information through the onboard satellite navigation and positioning equipment and calculates the current corrected real-time position of the UAV based on the differential correction information, and sends it to the ground command and control system via a wireless link.

[0061] Step 4: According to the real-time position information of the UAV and the pre-calibrated origin position information of the runway coordinate system group, select the runway coordinate system that is closest to the UAV position and where the UAV is located in the positive direction of the X-axis as the current reference runway coordinate system.

[0062] Step 5, based on the approximate conversion formula, calculate the lateral deviation of the aircraft relative to the centerline of the runway in real time.

[0063] It is worth mentioning that the present invention does not need to add additional sensors, and only optimizes the approximate calculation of the lateral deviation from an algorithm perspective.

[0064] It is worth mentioning that the present invention does not significantly increase the amount of calculation, but only increases the number of pre-calibrated points before the task, and will not cause obvious calculation burden during the actual task.

[0065] See also Figure 2 , Figure 2 This is a schematic diagram of an airport runway model.

[0066] like Figure 2 , 10 runway coordinate systems are evenly divided along the runway centerline, and a total of 11 calibration points are determined, and each calibration point O jThe runway coordinate system O is established by taking the X axis as the origin and the runway centerline as the X axis. The nose direction is positive, the vertical direction to the left of the X axis is the positive direction of the Y axis, and the vertical direction of the X and Y axes is the Z axis. j XYZ.

[0067] During the take-off and landing mission, the aircraft will move along the centerline of the runway from coordinate system O1X1Y1Z1 to coordinate system O 10 X 10 Y 10 Z 10 , the runway length is about 4000m.

[0068] In practical applications, the runway division density can be determined based on the runway length, whether the take-off and landing environment is ideal, and the calibration workload.

[0069] See also Figure 3 , Figure 3 It is a simulation diagram of the algorithm based on the segmented sideslip error correction method of the present invention.

[0070] like Figure 3 The blue line represents the lateral deviation calculated using the traditional approximate method. As the distance between the UAV and the origin of the airport coordinate system increases, the error of the calculated lateral deviation increases rapidly.

[0071] like Figure 3 , the red line represents the sideslip amount calculated using the segmented sideslip error correction method proposed in the present invention. The sideslip error increases in the current corresponding coordinate system. Once the aircraft enters the next coordinate system, the sideslip error is significantly corrected.

[0072] like Figure 3 The simulation results of a runway of about 4 kilometers show that the lateral error of the traditional approximate method reaches 0.857601m. In actual tasks, the lateral error is even greater when considering crosswind, line of sight, etc. The lateral error calculated by the method proposed in this invention is only 0.085751, and the maximum error is reduced by 90% compared with the traditional method.

[0073] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application shall be the common meanings understood by the general technicians in the field to which this application belongs. The words "upper", "lower", "left", "right", "center", "vertical", "horizontal", "inside", "outside" and other words indicating orientation used in the description of this application are only used to indicate the relative direction or positional relationship, and do not imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. When the absolute position of the described object changes, its relative positional relationship may also change accordingly, so it cannot be understood as a limitation on this application. The "first", "second", "third" and similar terms used in the description of this application are only used for descriptive purposes to distinguish different components, and cannot be understood as indicating or implying relative importance. The similar words "one", "one" or "the" used in the description of this application should not be understood as an absolute limitation on quantity, but should be understood as the existence of at least one. The similar words "including" or "comprising" used in the description of this application mean that the elements or objects appearing in front of the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0074] In addition, it should be noted that, unless otherwise clearly specified and limited, the words "installed", "connected", "connected" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or the internal connection of two components. Technical personnel in the field can understand their specific meanings in this application according to the specific circumstances.

[0075] The above description is only a specific implementation mode of the present invention and is not intended to limit the present invention. Within the spirit and principle of the present invention, any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the technical solution content of the present invention, any modification, equivalent replacement, improvement, etc. made should be included in the protection scope of the present invention.

Claims

1. A method for filtering and correcting take-off and landing lateral deviation error values ​​based on a segmented coordinate system, characterized in that: A segmented airport coordinate system is used to continuously update the lateral displacement of the UAV relative to the runway centerline, effectively reducing the accumulated lateral error, smoothing the error peak, and keeping the lateral estimation error within a tolerable range, effectively alleviating the high risk caused by large errors in key parameters during the take-off and landing phase of high-speed UAVs.

2. The method according to claim 1, characterized in that The steps include: Step 1: Consider the number of calibration points and the accuracy requirements of the offset to determine the number of airport segments and the points to be calibrated. For fixed airports, use satellite positioning and calibration equipment to divide the available distance of the airport runway centerline into N segments in our environment. Step 2: Use differential calibration equipment to obtain the longitude, latitude, and altitude position information of the point to be calibrated in advance, establish an airport coordinate system group, and obtain the runway direction information according to the runway heading approximate calculation formula; At this point, the preparatory work for calculating the aircraft's lateral deviation relative to the runway centerline has been completed. Step 3: During the mission, the UAV collects satellite navigation and positioning information through the onboard satellite navigation and positioning equipment and calculates the current corrected real-time position of the UAV by combining the differential correction information, and sends it to the ground command and control system through a wireless link; Step 4: According to the real-time position information of the UAV and the origin position information of the pre-calibrated runway coordinate system group, select the calibration coordinate system closest to the UAV position as the current matching runway coordinate system; Step 5: According to the approximate conversion formula Δ y =-(R+h)cos(θ)cos(L j )×δλ+(R+h)sin(θ)×δL, real-time calculation of the aircraft's lateral deviation Δ relative to the runway centerline y , where R represents the local radius of the earth without considering the eccentricity, h represents the altitude of the aircraft, θ represents the direction of the airport runway, and L j represents the latitude of calibration point j, δλ represents the longitude error of the aircraft's real-time position relative to the current calibration point, and δL represents the latitude error of the aircraft's real-time position relative to the current calibration point.

3. The method according to claim 2, characterized in that It also includes the purpose of step 6: providing the UAV pilot with the aircraft's lateral deviation relative to the runway centerline in real time, providing the pilot with a more accurate and intuitive aircraft position, which can be used for visual display and mission planning landing instructions.

4. The method according to claim 2, characterized in that Before step 1, the aircraft should have the capability of real-time positioning, and the take-off and landing airport runways should be known.

5. The method according to claim 2, characterized in that The N segments in step 1 are specifically: if a 3000m long runway is divided into 300m segments, then N=10, and a total of 11 calibration points need to be calibrated.

6. The method according to claim 2, characterized in that The selection of the number of segments N in step 1 follows the following principle: the longer the runway, the more segments, and the denser the calibration points, the more frequent the offset error correction, the more suppressed the divergence, and the greater the pre-calibration workload and real-time calculation workload.

7. The method according to claim 2, characterized in that The establishment of the coordinate system in step 2 is specifically as follows: a total of N+1 points need to be calibrated. j The position coordinates (λ j L j h j ), where λ j O j Point longitude value, L j O j Point longitude value, h j O j Point longitude value; in O j The runway coordinate system O is established with the centerline of the runway as the coordinate origin, the X axis as the runway centerline, the aircraft passing direction as the positive direction, the vertical direction to the left of the positive X axis as the positive Y axis, and the vertical direction of the X and Y axes as the Z axis. j XYZ.

8. The method according to claim 2, characterized in that Before step 4, the aircraft should be in the approach glide path or the pass-through stage, that is, at this time there is a need to calculate the side deviation to assist the aircraft to align with the centerline of the target airport; before step 4, the aircraft should have passed at least one calibration point, that is, the aircraft is located in the positive interval of the X-axis of at least one calibration coordinate system, and only then will the side deviation correction be performed; one method of selecting a matching calibration coordinate system in step 4 is: selecting the calibration point closest to the aircraft as the current matching calibration coordinate system.

9. The method according to claim 2, characterized in that In step 4, the UAV will pass through runway systems 1 to N in sequence during the take-off and landing phase, and may stop on a runway system midway. The lateral displacement is calculated based on the currently matched calibrated runway system, and P(λL h) is used to represent the position coordinates of the UAV.

10. The method according to claim 2, characterized in that In step 5, even if the real-time position information of the UAV and the origin position information of the pre-calibrated runway coordinate system group are completely accurate, errors will still be introduced in the side deviation calculation due to the coordinate system conversion, which is also the suppression goal of this method.

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