CN112699531B - Method for establishing general aviation low-altitude flight visual reference point - Google Patents
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Abstract
The invention discloses a method for establishing a general aviation low-altitude flight visual reference point, which specifically comprises the following steps: s1, regarding the earth as a standard sphere, adopting the radius R=6356.863019 km of the equiangular sphere as the radius of the earth, and taking O as the center of the sphere, and assuming that any two non-coincident points A (lon A, latA) and B (lon B, latB) exist on the earth; s2, assuming a point A to be a flight plan departure point, a point B to be a plan landing point, and calculating the distance between AB and the heading of the point B relative to the point A under an earth model. The general aviation low-altitude flight visual reference point establishing method can calculate the specific position of each reference point by taking the earth as a sphere, and can perform mutual operation when encountering ground features with obvious characteristics such as residential points, rivers, water systems and the like, thereby improving the whole application range, reducing the potential safety hazard during aviation low-altitude flight, ensuring the safety of the flight process of a flight person and reducing the loss of the user to a certain extent.
Description
Technical Field
The invention relates to the technical field of reference point establishment, in particular to a general aviation low-altitude flight visual reference point establishment method.
Background
The low-altitude flight is a flight between 100m and 1000m away from the ground, and is suitable for training, parachute landing, air drop, reconnaissance, strong impact, agriculture and forestry and other operations. Another: the method is divided into ultra-low-altitude flight (below 100m from the ground, can be used for agriculture and forestry operation, tourism, search and rescue, strong impact, separation from enemy areas and the like), low-altitude flight (the height is 100-1000 m, can be used for training, parachute landing, air drop, reconnaissance, strong impact, agriculture and forestry operation and the like), hollow flight (the height is 1000-7000 m, can be used for training, patrol, bombing and aerial flight), and visual navigation in the visual flight process of the low-altitude flight of the aircraft, wherein a reference point is required every 30 minutes for visual navigation, the visual flight is assisted, the safety of the flight process of the aircraft is ensured, the establishment of the existing visual reference point is not very strict, and the method is mostly based on the feeling of the flight of the aircraft, so the whole method is not very good, and a certain potential safety hazard exists.
Disclosure of Invention
(one) solving the technical problems
Aiming at the defects of the prior art, the invention provides a general aviation low-altitude flight visual reference point establishment method, which solves the problem that the aviation low-altitude flight visual reference point establishment method is inaccurate.
(II) technical scheme
In order to achieve the above purpose, the invention is realized by the following technical scheme: a method for establishing a general aviation low-altitude flight visual reference point specifically comprises the following steps:
s1, regarding the earth as a standard sphere, adopting the radius R=6356.863019 km of the equiangular sphere as the radius of the earth, and taking O as the center of the sphere, and assuming that any two non-coincident points A (lon A, latA) and B (lon B, latB) exist on the earth;
s2, assuming a point A to be a flight plan departure point, a point B to be a plan landing point, and calculating the distance between AB and the course of the point B relative to the point A under an earth model, wherein the specific calculation process is as follows: the distance L of the AB is a great circle distance between any two waypoints on a high altitude route map, namely the inferior arc length of a great circle passing through the two points by taking the sphere center of the earth as the circle center, under a spherical earth model, the great circle distance of the AB is the length of a unique great circle AB arc section determined by the points A and B and the sphere center, a spherical cosine formula is generally adopted for great circle distance calculation, when the floating point calculation precision of the system is not high, a great error exists when the distance between the two points which are close is calculated, and the short distance between the flying point and the landing point is considered, so that the Haverine formula is adopted, the limitation on the calculation precision of the system when the short distance calculation is not existed, and even if the distance is small, enough precision and effective figures can be kept, and the specific calculation is as follows:
s3, calculating an overall course angle, wherein the course angle is an included angle of the AB navigation direction relative to the north direction, the course angle of the arc AB at the point A is an included angle between a tangent line of the point A and the north direction, a traditional spherical sine formula cannot be used based on calculation accuracy, and a polar coordinate method is adopted, and the method is as follows:
s4, establishing a visual reference point between the flying point A and the landing point B, wherein the visual reference point is arranged at intervals of 30 minutes according to visual navigation requirements, the position needing visual reference on the route is calculated firstly by the calculation of the visual reference point, the interval distance of the reference point is calculated firstly, and the visual reference point is calculated based on the interval time standard of the reference point and the planned flying speed, wherein the formula is as follows: d=v×t;
s5, calculating the number of the reference points, and calculating based on the distance between the AB points and the distance between the reference points, wherein the formula is N=ceil (L/d) -1;
s6, estimating a visual reference position to be established in flight, calculating based on the distance between two points of the AB and the number of the reference points, dividing the AB major arc segment into N+1 parts according to the number N of the reference points, dividing the AB major arc segment into 3 parts by the points P1 and P2, indicating that 2 reference points to be established in the flight of the segment, and providing visual reference points when the flight reaches the vicinity of the points P1 and P2, wherein the position calculation process for establishing the reference points Pi in the flight is as follows: calculating the distance from the reference point Pi to the starting point A, D (AP i ) Calculating Pi (lonl, latI) position based on latitude and longitude coordinates of the start point a, azimuth of AB, and distance Pi from the point a,
latI＝arcsin(szcl+ca*slcosβ))
lonI＝lonA+atan2(sinβ*sl*cz，cl-sz*sin(latI))；
s7, finding a matched reference point based on the reference point required to be found, selecting a proper radius as a circle for each position Pi required to be established for visual reference on the route, performing intersection operation with ground features with obvious characteristics of the residential site, the river and the water system, reducing the radius until the intersection point is unique when a plurality of intersection points exist, and taking the ground feature at the intersection point as an ith reference point until all the reference points are established.
Preferably, in S1, lon a and lon B are the longitudes of point a and point B, respectively, and latA and latB are the latitudes of point a and point B, respectively.
Preferably, in S2, R is the earth radius, and L represents the great circle distance between AB, i.e., the distance of AB.
Preferably, in S3, θ is an AB heading angle.
Preferably, in S4, T is the reference point interval time in hours, where the value is 0.5, v is the planned flight speed in km/h.
Preferably, in S5, L is the distance between two points AB, d is the reference point spacing distance calculated in the previous step, ceil represents an upward integer of data.
Preferably, in S6, cl=cos (D (APi)/R), sl=sin (D (APi)/R), sa=sin (latA), ca=cos (latA), D (APi) are distances from the reference point to the starting point a to be established, β is the azimuth angle of the route AB, and R is the spherical model radius.
Preferably, in the step S7, in the process of establishing the reference points, after all the reference points are established according to the actual situation, the establishment of the visual reference points is completed.
Preferably, in S1, the earth' S surface is regarded as a sphere from a general wide view, although it is rugged.
Preferably, in S4, the aircraft such as an airplane has a cruising speed while flying, and thus the speed is taken as an average value.
(III) beneficial effects
The invention provides a method for establishing a visual reference point of a general aviation low-altitude flight. The beneficial effects are as follows: the method for establishing the universal aviation low-altitude flight visual reference point comprises the following steps: s1, regarding the earth as a standard sphere, adopting the radius R=6356.863019 km of the equiangular sphere as the radius of the earth, and taking O as the center of the sphere, and assuming that any two non-coincident points A (lon A, latB) and B (lon B, latB) exist on the earth; the earth can be used as a sphere, the specific position of each reference point is calculated, and the earth can be operated mutually when meeting the ground objects with obvious characteristics such as residential points, rivers, water systems and the like, so that the whole application range is improved, the potential safety hazard in aviation low-altitude flight is reduced, the safety of the flight process of a flight person is ensured, and the loss of the user is reduced to a certain extent.
Drawings
Fig. 1 is a schematic diagram of the longitude and latitude great circle distance of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, the embodiment of the invention provides a technical scheme: a method for establishing a general aviation low-altitude flight visual reference point specifically comprises the following steps:
s1, regarding the earth as a standard sphere, adopting an equiangular sphere radius R=6356.863019 km as the sphere center, assuming that the earth has any two non-coincident points A (lon A, latA) and B (lon B, latB), for land application, the rotational ellipsoid is a reasonable approximation of the average sea level, the error is +/-100 m, the flatness of the ellipsoid is very small, about 1/300, the flying distance of low-altitude visual flight is short, the interval between the flying point and the landing point is short, and the flatness of the ellipsoid is almost negligible, so that the earth surface can be approximately simulated by using a sphere model;
s2, assuming a point A to be a flight plan departure point, a point B to be a plan landing point, and calculating the distance between AB and the course of the point B relative to the point A under an earth model, wherein the specific calculation process is as follows: the distance L of the AB is a great circle distance between any two waypoints on a high altitude route map, namely the inferior arc length of a great circle passing through the two points by taking the sphere center of the earth as the circle center, under a spherical earth model, the great circle distance of the AB is the length of a unique great circle AB arc section determined by the points A and B and the sphere center, a spherical cosine formula is generally adopted for great circle distance calculation, when the floating point calculation precision of the system is not high, a great error exists when the distance between the two points which are close is calculated, and the short distance between the flying point and the landing point is considered, so that the Haverine formula is adopted, the limitation on the calculation precision of the system when the short distance calculation is not existed, and even if the distance is small, enough precision and effective figures can be kept, and the specific calculation is as follows:
s3, calculating an overall course angle, wherein the course angle is an included angle of the AB navigation direction relative to the north direction, the course angle of the arc AB at the point A is an included angle between a tangent line of the point A and the north direction, a traditional spherical sine formula cannot be used based on calculation accuracy, and a polar coordinate method is adopted, and the method is as follows:
s4, establishing a visual reference point between the flying point A and the landing point B, wherein the visual reference point is arranged at intervals of 30 minutes according to visual navigation requirements, the position needing visual reference on the route is calculated firstly by the calculation of the visual reference point, the interval distance of the reference point is calculated firstly, and the visual reference point is calculated based on the interval time standard of the reference point and the planned flying speed, wherein the formula is as follows: d=v×t;
s5, calculating the number of the reference points, and calculating based on the distance between the AB points and the distance between the reference points, wherein the formula is N=ceil (L/d) -1;
s6, estimating a visual reference position to be established in flight, calculating based on the distance between two points of the AB and the number of the reference points, dividing the AB major arc segment into N+1 parts according to the number N of the reference points, dividing the AB major arc segment into 3 parts by the points P1 and P2, indicating that 2 reference points to be established in the flight of the segment, and providing visual reference points when the flight reaches the vicinity of the points P1 and P2, wherein the position calculation process for establishing the reference points Pi in the flight is as follows: calculating the distance from the reference point Pi to the starting point A, D (AP i ) Calculating Pi (lonl, latI) position based on latitude and longitude coordinates of the start point a, azimuth of AB, and distance Pi from the point a,
latI＝arcsin(sa*cl+ca*sl*cosβ))
lonI＝lonA+atan2(sinβ/sl*ca，cl-sa*sin(latI))；
s7, finding a matched reference point based on the reference point required to be found, selecting a proper radius as a circle for each position Pi required to be established for visual reference on the route, performing intersection operation with ground features with obvious characteristics of the residential site, the river and the water system, reducing the radius until the intersection point is unique when a plurality of intersection points exist, and taking the ground feature at the intersection point as an ith reference point until all the reference points are established.
In the present invention, in S1, lon a and lon B are the longitudes of point a and point B, respectively, and latA and latB are the latitudes of point a and point B, respectively.
In the present invention, in S2, R is the earth radius, and L is the great circle distance between AB, i.e., the distance of AB.
In the present invention, in S3, θ is an AB course angle.
In the invention, in the step S4, T is the interval time of the reference point, the unit is hour, the value is 0.5, V is the planned flying speed, and the unit is kilometer/hour.
In the invention, in the step S5, L is the distance between the two points AB, d is the reference point interval distance calculated in the previous step, and Ceil represents the upward integer of the data.
In the present invention, in S6, cl=cos (D (APi)/R), sl=sin (D (APi)/R), sa=sin (latA), ca=cos (latA), D (APi) are distances from the reference point to the starting point a to be established, β is the azimuth angle of the route AB, and R is the spherical model radius.
In the invention, in the step S7, in the process of establishing the reference points, after all the reference points are established according to the actual situation, the establishment of the visual reference points is completed.
In the present invention, in S1, the earth' S surface is regarded as a sphere in a general broad range, although it is uneven.
In the present invention, in S4, the aircraft such as an airplane has a cruising speed during the flight, and thus the speed is taken as an average value.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (1)
1. A method for establishing a general aviation low-altitude flight visual reference point is characterized by comprising the following steps of: the method specifically comprises the following steps:
s1, regarding the earth as a standard sphere, adopting the radius R=6356.863019 km of the equiangular sphere as the radius of the earth, and taking O as the center of the sphere, and assuming that any two non-coincident points A (lon A, latA) and B (lon B, latB) exist on the earth;
s2, assuming a point A to be a flight plan departure point, a point B to be a plan landing point, and calculating the distance between AB and the course of the point B relative to the point A under an earth model, wherein the specific calculation process is as follows: the distance L of the AB is a great circle distance between any two waypoints on a high altitude route map, namely the inferior arc length of a great circle passing through the two points by taking the sphere center of the earth as the circle center, under a spherical earth model, the great circle distance of the AB is the length of a unique great circle AB arc section determined by the points A and B and the sphere center, a spherical cosine formula is generally adopted for great circle distance calculation, when the floating point calculation precision of the system is not high, a great error exists when the distance between the two points which are close is calculated, and the short distance between the flying point and the landing point is considered, so that the Haverine formula is adopted, the limitation on the calculation precision of the system when the short distance calculation is not existed, and even if the distance is small, enough precision and effective figures can be kept, and the specific calculation is as follows:
s3, calculating an overall course angle, wherein the course angle is an included angle of the AB navigation direction relative to the north direction, the course angle of the arc AB at the point A is an included angle between a tangent line of the point A and the north direction, a traditional spherical sine formula cannot be used based on calculation accuracy, and a polar coordinate method is adopted, and the method is as follows:
s4, establishing a visual reference point between the flying point A and the landing point B, wherein the visual reference point is arranged at intervals of 30 minutes according to visual navigation requirements, the position needing visual reference on the route is calculated firstly by the calculation of the visual reference point, the interval distance of the reference point is calculated firstly, and the visual reference point is calculated based on the interval time standard of the reference point and the planned flying speed, wherein the formula is as follows: d=v×t;
s5, calculating the number of the reference points, and calculating based on the distance between the AB points and the distance between the reference points, wherein the formula is N=ceil (L/d) -1;
s6, estimating a visual reference position to be established in flight, calculating based on the distance between two points of the AB and the number of the reference points, dividing the AB major arc segment into N+1 parts according to the number N of the reference points, dividing the AB major arc segment into 3 parts by the points P1 and P2, indicating that 2 reference points to be established in the flight of the segment, and providing visual reference points when the flight reaches the vicinity of the points P1 and P2, wherein the position calculation process for establishing the reference points Pi in the flight is as follows: calculating the distance from the reference point Pi to the starting point A, D (AP i ) Calculating the position of Pi (lonl, latI) based on the latitude and longitude coordinates of the starting point a, the azimuth of AB, and the distance of Pi from the point a, wherein lonl, latI refers to the corresponding latitude and longitude of the reference point Pi to be established in flight;
latI＝arcsin(sa*cl+ca*sl*cosβ)
lonI＝lonA+a tan2(sinβ*sl*ca，cl-sa*sin(latI))；
s7, finding a matched reference point based on the reference point required to be found, selecting a proper radius as a circle for each position Pi required to be established for visual reference on the route, performing intersection operation with ground features with obvious characteristics of the residential site, the river and the water system, and reducing the radius until the intersection point is unique when a plurality of intersection points exist, wherein the ground feature at the intersection point is used as an ith reference point until all the reference points are established;
in the S1, lonA and lonB are longitudes of a point A and a point B, respectively, and latA and latB are latitudes of the point A and the point B, respectively;
in the S2, R is the radius of a spherical model;
in the step S3, θ is an AB course angle;
in the step S4, T is the reference point interval time, the unit is hour, the value is 0.5, V is the planned flying speed, and the unit is kilometer/hour;
in the step S5, L is the distance between the two points AB, d is the reference point interval distance calculated in the previous step, and Ceil represents that the data is taken up by an integer;
in S6, cl=cos (D (APi)/R), sl=sin (D (APi)/R), sa=sin (latA), ca=cos (latA), D (APi) is the distance from the reference point to be established to the starting point a, β is the azimuth angle of the route AB, and R is the spherical model radius;
in the step S7, in the process of establishing the reference points, after all the reference points are established according to actual conditions, the establishment of the visual reference points is completed;
the lonl, latI refers to the corresponding longitude and latitude needed to establish the reference point Pi in flight.
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