RU2758285C1 - Method for group video navigation of aircraft - Google Patents

Abstract

FIELD: navigation equipment.

SUBSTANCE: invention relates to navigation and is intended for calculating the coordinates of aircraft. It can be used both for autonomous navigation and for working in combination with other navigation tools. The proposed method consists in the fact that pairs of monocular vision systems (MVS) of the trail and the lead aircraft of the group form binocular systems, the mutual location of digital cameras of which is determined by an optoelectronic inter-aircraft navigation system, which consists of three laser wide-directional tags of the lead aircraft and the MVS of the trail aircraft. The joint functioning of the MVS pairs is ensured by the exchange of information through a two-way optical-electronic communication line. To determine the current coordinates of the lead aircraft, images of at least three optical contrasts of the earth’s surface are used on the cameras of the trail and the lead aircraft in two consecutive photo expositions, the increments of the coordinates of the master are calculated, these increments are averaged for all pairs of trail and lead aircraft, and then the coordinate increments are calculated during the flight and summed with the initial coordinates of the aircraft.

EFFECT: expansion of the possibilities of using groups of small-sized unmanned aircraft, each of which is equipped with only one video camera.

1 cl, 2 dwg

Description

The invention relates to navigation and is intended for reckoning the coordinates of a group of aircraft (AC). It can be used both for autonomous navigation and for work in conjunction with other navigation systems.

There is a known method for determining the orientation of a moving object according to the coordinates of reference sources (RI), including the determination of signals corresponding to the position of the RI image in the plane of the photodetector, determining the bearing angles of each RI using the received signals, taking into account the focal length of the lens and determining the coordinates of the RI according to the bearing angles, taking into account distance between RI.

This method is implemented in a device containing reference sources on a moving object, and on a stationary one - two photodetecting optical-location units and a unit for determining the coordinates of the RI and the orientation of the moving object, described in the patent for invention [GB Patent No. 2002986 A, publ. 02/28/1979].

The disadvantage of the described analogue is the use of reference sources with a known location on the moving object, which ensures that only the orientation of the moving object is determined at an unknown location, that is, it cannot provide navigation of the object.

Known closest to the claimed invention is a method of video navigation of a mobile object, based on sequential photo exposure of the earth's surface by cameras of a stereo pair installed on a mobile object, highlighting at least three special points of the earth's surface on the image of each camera, calculating their coordinates in a related coordinate system, determining the angular and linear moving a moving object relative to the earth's surface during the time interval between two photo exposures, determining the angular and linear movement of the moving object during the movement and determining the current coordinates of the location, described in the patent for invention RU No. 2626017, Publ: 21.07.2017 [2].

The disadvantage of this method is the impossibility of using it to solve the problem of reckoning coordinates by means of a stereo pair installed on a small unmanned aerial vehicle, since a significant distance between the cameras of the stereo pair is required to achieve high measurement accuracy.

The technical result of the invention is achieved by the fact that in the method of video navigation of a mobile object, based on photo exposure of the earth's surface with a stereo pair, processing its digitized images and calculating the coordinates of the location of the moving object, the radiation of three laser marks with a wide directivity pattern is recorded, installed on the leading aircraft of the group by means of the onboard camera of the slave The aircraft carry out the processing of the digitized image of laser marks, determine the coordinates of their images on the photomatrix, determine the linear and angular coordinates of the relative position of the master and slave aircraft, use the video cameras of the master and slave to take photographic exposure, stereo identification and determine the coordinates of the images of three special points of the earth's surface that do not lie on one straight line at the moments of two successive photo exposures of cameras, the increment of the linear and angular coordinates of the leading aircraft relative to the earth's surface is calculated over time i between photo exposures and averaging them for all aircraft of the group, calculating the increment of the linear and angular coordinates of the leading aircraft relative to the earth's surface during the flight, calculating the position of the leading aircraft taking into account its initial coordinates.

The essence of the invention lies in the fact that the earth's surface is photo-exposed with a stereo pair, its digitized images are processed and the coordinates of the location of the moving object are calculated, characterized in that the radiation of three laser marks with a wide directivity pattern, installed on the leading aircraft of the group by means of the on-board camera of the slave aircraft, is processed, and the digitized images of laser marks, determine the coordinates of their images on the photomatrix, determine the linear and angular coordinates of the relative position of the master and slave aircraft, photographic exposure, stereo identification and determination of the coordinates of the images of three special points of the earth's surface that do not lie on the same straight line at the moments two successive photo exposures of cameras, calculate the increment of the linear and angular coordinates of the leading aircraft relative to the earth's surface during the time between photo exposures and average them for all aircraft groups, calculate the increment of the linear and angular coordinates of the leading aircraft relative to the earth's surface during the flight, calculate the location of the leading aircraft, taking into account its initial coordinates.

The method provides for expanding the possibilities of using groups of small-sized unmanned aerial vehicles, each of which is equipped with only one video camera. In this case, a critical condition is the ability to accurately determine their relative position. Consider the problem of determining the location of two aircraft (the leader and one of the wingmen of the group), equipped with monocular vision systems and flying in formation, relative to the earth's surface.

FIG. 1 shows the optical diagram of the reckoning of coordinates, which shows the location of three laser IR marks M ₁ , M ₂ and M ₃ on the master aircraft ₁ and the coordinate system O ₁ X ₁ Y ₁ Z ₁ associated with it, as well as the coordinate system O ₂ X ₂ Y ₂ Z ₂ connected to the slave aircraft ₂ and a camera with its elements, a _{photo lens FO 2} and a photosensitive matrix FM ₂ with images of marks S ₁ , S ₂ and S ₃ on it, installed on the slave aircraft, in the process of determining the angular orientation and location of the master aircraft relative to the slave, P _{n, m} - the n-th point on the earth's surface (n = 1 ... 3) at the moment of the m-th photo exposure, -S1n, m, S2 _{n, m} - images of the point P _{n, m} on photomatrices FM1 and FM2 , F ₁ , F ₂ - optical centers of photo lenses.

FIG. 2 shows the structure of a group video navigation system, which includes two monocular vision systems located on two unmanned aerial vehicles, informationally connected by means of an interplane navigation system. The monocular vision system of the master and slave aircraft includes the following elements: camera (1, 2); digital computer (3, 4); photodetector (5, 6); three laser IR tags (M ₁ , M ₂ , M ₃ and M ₄ , M ₅ , M ₆ ).

The method is implemented as follows.

Rectangular coordinate system O ₂ X ₂ Y ₂ Z ₂ associated with the driven aircraft (Fig. 1), the axis O ₂ X ₂ is parallel to the longitudinal axis of the aircraft, O ₂ Z ₂ is parallel to the transverse axis, and the O ₂ Y ₂ axis complements them to right coordinate system. Photosensitive matrix FM ₂ , placed in the focal plane of the photo lens FO, is in the plane of coordinates O ₂ Y ₂ Z ₂ . The optical axis of the photo lens O ₂ X _{2 is} parallel to the longitudinal axis of the aircraft. The O ₁ X ₁ Y ₁ Z ₁ coordinate system is associated with the leading aircraft, where the O ₁ X ₁ axis is directed along the longitudinal aircraft axis, the O ₁ Z ₁ axis is the aircraft's transverse axis, and the O ₁ Y ₁ axis complements them to the right coordinate system. In this coordinate system, three points M ₁ , M ₂ , M ₃ (laser IR marks) are considered, associated with the ends of structural elements, and it is important that these points do not overlap with other elements at any relative positions of the aircraft.

The equations describing the position of the slave aircraft ₂ relative to the master, obtained in [Patent RU No. 2700908, Publ: 09/23/2019] have the form

- фокусное расстояние объектива фотокамеры;

- координаты лазерных меток в системе координат связанной с ведущим ЛА; X₁, Y₁, Z₁, α, β, χ - искомые координаты взаимного положения ведомого относительно ведущего; a_ij(i,j=1..3) - коэффициенты матрицы A направляющих косинусов, описывающие угловое движение ведомого ЛА относительно ведущегоwhere

- focal length of the camera lens;

- coordinates of laser marks in the coordinate system associated with the leading aircraft; X ₁ , Y ₁ , Z ₁ , α, β, χ - the required coordinates of the relative position of the follower relative to the leader; a _ij (i, j = 1..3) are the coefficients of the matrix A of the direction cosines describing the angular motion of the driven aircraft relative to the leading

и угловые

координаты ведомого летательного аппарата относительно ведущего. Решение этой системы уравнений осуществляется методом Ньютона-Рафсона.Using the solution of the system of equations (1), linear

and corner

the coordinates of the slave aircraft relative to the master. The solution of this system of equations is carried out by the Newton-Raphson method.

In the presence of measured values of linear X ₁ , Y ₁ , Z ₁ and angular α, β, χ coordinates of the slave aircraft relative to the master, monocular vision systems of aircraft ₁ and ₂ are used to create a binocular system, while forming a two-way exchange of information used for calculations by means of optoelectronic measuring instruments (laser tags and photodetectors).

To describe the functioning of such a technical vision system, let us express the relationship between the measured coordinates X ₁ , Y ₁ , Z ₁ , α, β, χ, as well as the coordinates of the images of singular points on the photomatrices of the binocular STZ. The connection between the unit vectors of the coordinate systems O ₁ X ₁ Y ₁ Z ₁ and O ₂ X ₂ Y ₂ Z _{2 is} described by the known relations

where the transformation matrix has the form

и приравниваются правые части этих выражений:The vector is expressed in two ways

and the right-hand sides of these expressions are equated:

и

выражаются посредством следующих соотношений, которые следуют из подобия пар треугольников

и

а также запишем выражения векторов

и

Vectors

and

are expressed by means of the following relations, which follow from the similarity of pairs of triangles

and

and also write down expressions of vectors

and

и

- проекции векторов

и

на оси O₁X₁ и О₂Х₂;

- координаты изображения особой точки

на фотоматрицах ФМ1 и ФМ2;

и

- единичные орты в системах координат O₁X₁Y₁Z₁ и O₂X₂Y₂Z₂; F=OF=O₁F₁ - фокусное расстояние объектива; первый индекс в обозначении координат - номер фотоматрицы.where

and

- vector projections

and

on the axis O ₁ X ₁ and O ₂ X ₂ ;

- coordinates of the image of the singular point

on photomatrices FM1 and FM2;

and

- unit vectors in coordinate systems O ₁ X ₁ Y ₁ Z ₁ and O ₂ X ₂ Y ₂ Z ₂ ; F = OF = O ₁ F ₁ - lens focal length; the first index in the designation of coordinates is the number of the photomatrix.

и координат изображений особой точки на фотоматрицах бинокулярной СТЗ запишем в виде следующего соотношенияTaking into account the obtained expressions, we rewrite the vector equality (2), express the relationship between the vectors measured by the interslane navigation system

and the coordinates of the images of the singular point on the photomatrices of the binocular STZ we write in the form of the following relation

получимUsing expressions for unit vectors

get

Projecting the last equality on the axis of the coordinate system O ₁ X ₁ Y ₁ Z ₁ , we get

We use the following notation in these equations

получим

get

и

From these equations we express the unknowns

and

Using the previously obtained relations (3), we express the coordinates of the point P of the earth's surface in the coordinate system O ₁ X ₁ Y ₁ Z ₁

The obtained ratios make it possible to determine the coordinates of any contrasting point of the earth's surface in the coordinate system associated with the photomatrix of the leading aircraft. This gives grounds to speak about the possibility of constructing a measuring system of technical vision, located on two aircraft of the group, interconnected by an inter-aircraft navigation system.

земной поверхности посредством распределенной бинокулярной системы технического зрения, включающей фотокамеры 1, 2 и цифровые вычислители 3, 4 обоих ЛА. Информационное взаимодействие цифровых вычислителей осуществляется через двунаправленный оптико-электронный канал связи (фотоприемники 5 и 6 - лазерные метки M₁, М₂, М₃). Импульсное излучение лазерных меток имеет две составляющие - навигационную и информационную. Первая из них воздействует на фотокамеру 2 второго ЛА и обеспечивает измерение взаимного положения летательных аппаратов. Информационная составляющая сигналов лазерных меток обеспечивает взаимный обмен цифровых вычислителей 3 и 4, в которых осуществляется обработка изображений земной поверхности, отыскание оптических контрастов (Р) и их стереоотождествление, а также решение вычислительной задачи в соответствии с алгоритмом (соотношения 8).The work of the group video navigation system is reduced to measuring the coordinates of contrast points

the earth's surface by means of a distributed binocular vision system, including cameras 1, 2 and digital computers 3, 4 of both aircraft. Information interaction of digital computers is carried out through a bi-directional optoelectronic communication channel (photodetectors 5 and 6 - laser marks M ₁ , M ₂ , M ₃ ). Pulsed radiation of laser marks has two components - navigation and informational. The first of them acts on the camera 2 of the second aircraft and ensures the measurement of the relative position of the aircraft. The information component of the signals of the laser marks ensures the mutual exchange of digital computers 3 and 4, in which the images of the earth's surface are processed, the optical contrasts (P) are found and their stereo identification, as well as the solution of the computational problem in accordance with the algorithm (relations 8).

(индекс n=1, 2, 3, … - номер особой точки). Здесь прямоугольная система координат

связана с подвижным объектом в m-м пространственном положении (в m-й момент времени), фотоматрицы ФМ1, ФМ2 цифровых фотокамер 1 и 2 стереопары расположены в плоскости

а оптические оси объективов параллельны оси

Центры фотоматриц O_1,m (O_2,m) расположены симметрично относительно начала координат O_m (O_m+1 - его положение в m+1-й момент времени) на расстояниях В/2. Системы координат

и

лежат в плоскости фотоматриц, причем оси

и

параллельны оси

а оси

и

совпадают с осью

В точках F₁ и F₂ располагаются геометрические центры объективов левой и правой фотокамер, формирующих оптические изображения S_1m и S_2m особой точки земной поверхности

а в следующий момент времени - S_1m+1 и S_2m+1. Точки D₁ и D₂ - проекции точки P_1m на плоскости фотоматриц ФМ1 (O₁Y₁Z₁) и ФМ2 (O₂Y₂Z₂).Let us consider the scheme for measuring the spatial movement of the leading group of aircraft by means of the stereo pair cameras installed on them (Fig. 1), while a group of three special points is used on the earth's surface

(index n = 1, 2, 3,… is the number of the singular point). Here the rectangular coordinate system

is connected with a moving object in the m-th spatial position (at the m-th moment of time), photomatrix FM1, FM2 of digital cameras 1 and 2 of the stereo pair are located in the plane

and the optical axes of the lenses are parallel to the axis

The centers of the photo matrices O _{1, m} (O _{2, m} ) are located symmetrically relative to the origin of coordinates O _m (O _{m + 1} is its position at the m + 1st moment of time) at distances B / 2. Coordinate systems

and

lie in the plane of the photo matrices, and the axes

and

parallel axis

and the axes

and

coincide with the axis

At points F ₁ and F ₂ are the geometric centers of the lenses of the left and right cameras, forming optical images S _1m and S _{2m of the} singular point of the earth's surface

and at the next moment in time - S _{1m + 1} and S _{2m + 1} . Points D ₁ and D ₂ are projections of point P _1m on the plane of photo matrices FM1 (O ₁ Y ₁ Z ₁ ) and FM2 (O ₂ Y ₂ Z ₂ ).

The selection of at least three specific points of the earth's surface in the image of each camera can be performed by software processing of images of the earth's surface, which can be carried out, for example, by the method of fast checking of segments (FAST) of the brightness of points forming a circle of a given radius.

изображений трех особых точек

на фотоматрицах из положений в моменты времени m-й фотоэкспозиции обеспечивает вычисление координат

n-й особой точки

относительно подвижного объекта в связанной системе координат по формулам (8).Determination of coordinates

images of three special points

on the photomatrix from the positions at the moments of time of the m-th photoexposure provides the calculation of the coordinates

n-th singular point

relative to a moving object in a connected coordinate system according to formulas (8).

связанной с подвижным объектом, относительно ее предыдущего положения

задается вектором смещения начала координат

а изменение углового положения системы

- матрицей направляющих косинусов.Coordinate system position

associated with a moving object, relative to its previous position

given by the offset vector of the origin

and the change in the angular position of the system

- a matrix of direction cosines.

- углы последовательных разворотов подвижного объекта вокруг осей

соответственно, за время между двумя последовательными фотоэкспозициями.where

- angles of successive turns of the moving object around the axes

respectively, for the time between two successive photo exposures.

и

в системах

соответственноLet us write down the relation connecting the measured vectors

and

in systems

respectively

- вектор, с началом в точке

а конец в точке

отсчитанный в системе координат

а также очевидное векторное равенство, связывающее m и m+1 экспозицииwhere

- vector, with the origin at the point

and the end at the point

referenced in the coordinate system

and also the obvious vector equality connecting m and m + 1 exposures

измерить методом прямых измерений не возможно, то для того чтобы воспользоваться равенством (9), необходимо выразить этот вектор в проекциях на оси системы координат

получимSince the vector

it is not possible to measure by the method of direct measurements, in order to use equality (9), it is necessary to express this vector in projections on the axes of the coordinate system

get

а также вектора

и

доступные для прямых измерений, и для совокупности трех особых точек представляет собой систему 9 нелинейных алгебраических уравнений, которая может быть решена применением специальных численных методов, использующихся для таких переопределенных систем.The resulting ratio contains six unknown quantities

as well as vectors

and

available for direct measurements, and for a set of three singular points is a system of 9 nonlinear algebraic equations, which can be solved using special numerical methods used for such overdetermined systems.

To avoid this, we will find an analytical solution to the problem. We apply relation (10) for three singular points of the earth's surface, on the position of which the following condition is imposed, they form a triangle of nonzero area (do not lie on one straight line)

Subtracting the first from the second ratio, and the second from the third, we get

We also write down the relation describing the transformation of the coordinates of a vector equal to the vector product of these vectors, since, for our purpose, we need a vector that is not a linear combination of the selected vectors

We use the last three relationships to write a matrix relationship, in which column matrices take the place of columns in block matrices, such a notation follows from the matrix multiplication rule

From the last matrix equality, we express the required matrix (A _m ) by multiplying both sides of the equality on the right by the matrix inverse of the matrix factor (A _m ). Note that the determinant of this matrix is not equal to zero, since the three vectors whose coordinates are written in the columns of the matrix are linearly independent and, therefore, the inverse matrix exists.

непосредственно измеряются с помощью СТЗ в моменты m и m+1 экспозиций, то соотношение (12) используется для вычисления углового перемещения подвижного объекта относительно земной поверхности за интервал времени между двумя фотоэкспозициями. Для определения вектора линейного перемещения подвижного объекта

воспользуемся соотношением (11) при n=1.Since all the coordinates of the vectors in the matrix expression

are directly measured using the STZ at the moments of m and m + 1 exposures, then relation (12) is used to calculate the angular displacement of a moving object relative to the earth's surface during the time interval between two photo exposures. To determine the vector of linear displacement of a moving object

we use relation (11) for n = 1.

The matrix describing the rotational motion of the movable object from the initial to the final position is written in the form of a product of matrices describing the rotations during the time intervals between two successive photo exposures.

To determine the coordinates of a moving object, it is necessary to take into account its initial angular and spatial position, which will be set by the geographical coordinates ϕ ₀ - latitude, λ ₀ - longitude, R ₀ - distance from the center of the earth, and its angular position relative to the ground by course angles - ψ ₀ , roll - γ ₀ and pitch - υ ₀ , then the final angular position of the moving object is determined by means of the matrix.

where

Matrix defining the initial angular position of the movable object.

The problem of determining the initial position of a moving object in navigation is known as the initial exhibition of the system, and several well-known methods are used for its implementation.

We find the increments of geographical coordinates for one m-th time interval between successive photo exposures, and by summation we express the current coordinates of the moving object at the m-th (current) moment, while taking into account the initial location of the object. We calculate the current coordinates of the location of the moving object according to the following formulas

- элементы матрицы направляющих косинусов вида (15) определяемые текущими углами крена, курса и тангажа подвижного объекта.where

- elements of the matrix of direction cosines of the form (15) determined by the current angles of roll, course and pitch of the moving object.

Since the images of the earth's surface contain a significant number of contrast points, it is advisable to provide multiple measurements of the coordinates of a moving object with processing of their results. This will ensure the reduction of measurement errors, as well as monitoring the level of these errors.

Claims (1)

The method of group video navigation of aircraft, based on photographic exposure of the earth's surface with a stereo pair, processing of its digitized images and calculating the coordinates of the location of a moving object, characterized in that the radiation of three laser marks with a wide directivity pattern, installed on the leading aircraft of the group by means of the on-board camera of the slave aircraft, is carried out processing of the digitized image of laser marks to determine the coordinates of their images on the photomatrix, determine the linear and angular coordinates of the relative position of the master and slave aircraft, photographic exposure, stereo identification and determination of the coordinates of the images of three special points of the earth's surface that do not lie on one straight line are performed using the video cameras of the master and slave at the moments of two successive photo exposures of cameras, the increment of the linear and angular coordinates of one of the aircraft relative to the earth's surface is calculated during the flight, the location of the aircraft, taking into account its initial coordinates.

Images