RU2338158C1 - Method for aircraft navigation - Google Patents

Abstract

FIELD: physics, measurement.

SUBSTANCE: invention concerns radio location equipment and can be applied in modeling various radio location or similar systems for aircraft navigation using radio waves by aircraft location and travel control. Objective is achieved due to calculation of location correction signal for aircraft travel control by radio waves, using three coordinates. Aircraft navigation method involves reference site map plotted by conventional method before beginning of aircraft traffic, selection of measurement site of reference map, plotting current map by radio wave measurement of measurement site parametres, comparison of obtained measurement site data for current and reference maps, calculation of travel path correction signal on the basis of multipath three-coordinate measurement results, and aircraft travel control by its location correction during travel over measurement site.

EFFECT: enhanced response and accuracy of aircraft navigation method.

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Description

The invention relates to the field of radar technology and can be used in the construction of various radar or similar systems designed to determine the location of aircraft using radio waves and control the movement of aircraft.

To ensure the navigation of aircraft (LA) determine the location of the aircraft by measuring their current coordinates. The location of the aircraft is determined using radio waves for use in radar navigation systems.

Radar navigation systems are based on the correlation-extreme navigation methods (KESN), which ensure the search and tracking of the optimal flight mode of the aircraft [1]. KESN provide the measurement of indicators of the extreme regime of the aircraft, the processing of this information and the development of the control action to correct the coordinates of the location of the aircraft. Most often they use map-matching KESN according to geophysical fields, based on a comparison of current maps of the area obtained using radio waves with reference maps of the same area, a priori located on the aircraft, based on determining the location of the aircraft and then controlling the movement of the aircraft by correcting their location. Reference cards are installed on the aircraft until the start of movement over a given surface area, and current cards are received during the movement of the aircraft. The deviation of the reference terrain maps from the current at a given point trajectory of the aircraft determines the deviation of the actual trajectory from the given. As a result of comparing the reference and current terrain maps, corrections to the coordinates of the aircraft are developed to control the movement by correcting the location of the aircraft.

Comparison of the reference and current cards is carried out on the basis of the calculation of the functionals that reach the global extremum with full combination of images of these cards. To process the information obtained during the movement of the aircraft, difference algorithms are used, based on the calculation of the differences in the measured heights of the current map.

A known method of navigation of aircraft [2], used in correlation-extreme navigation systems and consisting in determining the location of the aircraft using radio waves emitted in the form of a single beam (hereinafter: radio waves in the form of a beam), allows you to take information at the current point.

The implementation of the method [2] is as follows.

Use the information of the reference map of the area about the navigation field of the earth, which is located on the aircraft before the start of movement.

Select a site of terrain (measured area), which is determined by the value of the permissible deviations of the aircraft in range (square of uncertainty).

(индекс «т» принадлежит текущей карте) от ЛА до рельефа мерного участка в i точках (i=1, 2, 3,...N) траектории движения ЛА (трассы

).The heights are measured using a single beam of radio waves.

(the “t” index belongs to the current map) from the aircraft to the relief of the measuring section at i points (i = 1, 2, 3, ... N) the trajectory of the aircraft (track

)

высот

, измеренные с помощью радиоволн, от высот H_oi, измеренных бародатчиком (абсолютная высота), в точках i траектории движения ЛАAfter passing the LA measured area, deviations are calculated

heights

measured using radio waves from the heights H _oi measured by the bar sensor (absolute height), at points i of the aircraft trajectory

после прохождения мерного участка, то есть получают карту высот рельефа мерного участка (плановые координаты мерного участка), для составления которой используют данные о скорости ЛА и углах эволюции (тангаж, крен и курс).Draw up a current map for the measured area based on the calculated elevation heights

after passing the measured area, that is, they receive a map of the elevation of the relief of the measured area (planned coordinates of the measured area), for compiling which data on the aircraft speed and evolution angles (pitch, roll and course) are used.

(индекс «э» принадлежит эталонной карте), направленные вдоль мерного участка с шагом j (j=1, 2, 3,...N) поперек мерного участка, соответствующим шагу эталонной карты (плановые координаты эталонной карты).Determined on the basis of a reference map of the terrain of the route

(the index “e” belongs to the reference map) directed along the measured section with a step j (j = 1, 2, 3, ... N) across the measured section corresponding to the step of the reference map (planned coordinates of the reference map).

Combine the current and reference maps of the study area.

и эталонное

значения путем корреляционно-экстремальной обработки реализации с использованием разностных алгоритмов КЭСН.Compare current

and reference

values by correlation-extreme processing of the implementation using KESN difference algorithms.

A signal for correcting the location of the aircraft in three coordinates is calculated based on an analysis of the mutual displacements of the reference and current terrain maps of the measured area.

Control the movement of the aircraft by correcting its location.

In this KESN, the aircraft trajectory is divided into two successive sections: measurement and correction.

The disadvantages of the method [2] is the following.

The generation of the correction signal only after the passage of the entire measured area.

The need to measure the aircraft’s absolute height above the zero level H _{about the} reference map, and additional calculations are needed to determine the average elevation levels of the measured map and the reference map. Carrying out such calculations does not allow for the operational processing of data during the movement of the aircraft over the measured area.

Low accuracy of compiling the current map using a single beam, since to measure the height to the studied area, the beam width of the radio waves should be wide enough. This reduces the accuracy of determining the range to individual points on the surface and, accordingly, decreases the accuracy of compiling the current map.

The lack of information about the current location of the aircraft in the process of moving over the measured area, since the processing of the measured information is carried out after the passage of the entire measured area.

A known method of navigation of aircraft [3], selected for the prototype.

The implementation of the method [3] is as follows.

Use the information of the reference map of the area about the navigation field of the earth, which is located on the aircraft before the start of movement.

Select a site of terrain (measured area), which is determined by the value of the permissible deviations of the aircraft in range (square of uncertainty).

Radio waves are emitted for measuring the parameters of the measured area in the form of rays, the number of which is at least three and is determined by the permissible time for measuring the location of the aircraft when moving over the measured area.

The oblique ranges to the surface under study are measured using radio waves, the first to emit a beam located in a plane orthogonal to the plane of the horizon of the studied surface (first beam), the next to emit rays whose propagation directions do not coincide with the propagation direction of the first ray, and the propagation directions of one part rays are located to the left (in the direction of movement of the aircraft) from the first ray, and the other part to the right (in the direction of movement of the aircraft) about a first beam, wherein the number of beams equal right and left from the first beam.

The coordinates of the measurement points in the coordinate system associated with the aircraft, as well as the elevation values at these points, are calculated from the obtained data on the inclined ranges, as well as on the angles of evolution of the aircraft.

The local coordinates of the projection of the current point of the aircraft trajectory on the plane of the planned coordinates are calculated.

The measurement differences of the first and all left rays, the first and all right rays in the current dimension are determined, and the measurement differences of the first ray in the current measurement and in the previous one are also calculated.

Using the reference map for each possible position of the aircraft inside the uncertainty square (hypothesis), the coordinates at each point are determined, for which the elevation of the terrain in the measured area is calculated.

The differences of measurements of the first and all left rays, the first and all right rays in the current measurement are determined, and the differences of measurements of the first ray in the current measurement and in the previous one from the reference map for each hypothesis are calculated.

For all hypotheses inside the square of uncertainty, the terms of the proximity indicator are calculated.

At the end of all measurements, an extremum of the proximity indicator is searched.

Corrections are given to the coordinates of the location of the aircraft in the planned coordinates of the measured area based on an analysis of the mutual displacements of the reference and current terrain maps of the measured area.

Control the movement of the aircraft by correcting its location.

The disadvantages of the method [3] is the following.

Determination of corrections only in the planned coordinates of the measuring section — determining the location of the aircraft by only two coordinates.

Low accuracy of controlling the movement of the aircraft, since there is no possibility of correcting the location of the aircraft in three coordinates of the reference map.

The technical result of the invention is to increase the accuracy of the navigation method of aircraft due to the fact that the calculation of the position correction signal for controlling the movement of aircraft using radio waves is carried out in three coordinates of the reference map when moving aircraft above the measured area.

The technical result is achieved by the fact that in the method of navigation of aircraft, which consists in using a reference map of the area as a priori information about the navigation field, selecting a plot of terrain (measured section) located within the reference map, compiling the current map by calculating the planned coordinates of the measured section based on measuring inclined ranges using the multipath measurement mode using radio waves emitted in the form of rays, determining the difference in the results of multipath measurements, comparing the values of the planned coordinates of the current and reference maps, calculating the signal of the correction of the trajectory of movement and controlling the movement of aircraft by correcting their location, correcting the location of the aircraft is carried out by three coordinates of the reference map (planned coordinates and height) in the coordinates of the measured area during the movement of the aircraft above measured area, and after determining the location of the aircraft in the planned coordinates of the measured area calculate the height of years apparatus in the coordinates of the measured area at the point of determining the location of the aircraft in the planned coordinates of the measured area as the sum of the height, which is the value of the measured oblique range, multiplied by the cosine of the angle of inclination of the beam relative to the perpendicular to the surface of the measured area, and the correction determined by the reference map, representing is the difference in the elevation of the relief of the measured area at the point of determination of the inclined range and the point located on the line of the perpendicular to the surface of the measured plot.

The technical result is achieved by the fact that when implementing the method of navigation of aircraft use the results of multipath measurements of the parameters of the measured area using radio waves in three coordinates of the reference map: the planned coordinates and altitude values. Therefore, to generate the signal for correcting the location of the aircraft and controlling their movement, not only the planned coordinates are used, but also the heights of the measured section. As a result, the navigation method allows you to adjust the location of the aircraft during the passage of the measured area with less error in comparison with the analogue and prototype.

The navigation method of the aircraft is explained by the following drawings:

- the figure 1 shows the relative position of the coordinate systems during the movement of the aircraft;

- figure 2 shows the measurement of the slant range for individual beams of radio waves;

- figure 3 shows the determination of the value of the current heights.

The navigation method of the aircraft is as follows.

Use the information of the reference map of the terrain, installed on the aircraft before the start of movement, about the navigation field of the earth.

Select the required area of the terrain of the reference map, which is a measured area and is determined by the value of the permissible deviations of the aircraft in range (uncertainty square).

Make up the current map by measuring the parameters of the measured area using radio waves. Rays of radio waves emit as follows. The first to emit a beam whose propagation direction is located in a plane orthogonal to the horizon plane of the measured section or in a plane that is at an angle to the horizontal plane of the measured section (first beam). Then, rays are emitted whose propagation directions do not coincide with the propagation direction of the first ray, and the propagation directions of one part of the rays are to the left (in the direction of the aircraft) from the first ray, and the other part to the right (in the direction of the aircraft) from the first ray. The number of rays to the right and left of the first ray is the same.

The location of the aircraft in the planned coordinates of the measured area is calculated based on measurements using beams of radio waves of inclined ranges from the aircraft to the surface of the measured area.

Calculations are performed similar to those described above, using a reference map for each possible position of the aircraft inside the uncertainty square for each hypothesis.

For all hypotheses inside the square of uncertainty, the terms of the proximity indicator are calculated.

At the end of all measurements, an extremum of the proximity indicator is searched.

The corrections to the coordinates of the location of the aircraft in the planned coordinates of the measured area are determined based on an analysis of the mutual displacements of the reference and current terrain maps of the measured area.

After determining the location of the aircraft in the planned coordinates of the measuring area, calculate the height of the aircraft above the surface of the measuring area in the coordinates of the measuring area (at the point of determining the location of the aircraft in the planned coordinates of the measuring area) as the sum of the height, which is the value of the measured oblique range, multiplied by the cosine of the beam angle relative to the perpendicular to the surface of the measured section, and the correction determined by the reference map, which is the difference in the height of the relief of the measured section at the point the inclined range and the point located on the line of the perpendicular to the surface of the measuring section.

Corrections are given to the coordinates of the location of the aircraft in the planned coordinates of the measuring area in three coordinates.

Control the movement of the aircraft by correcting their location in three coordinates as you progress through the measuring section.

The movement of the aircraft is controlled at the rate of receipt of the measured information, but with higher accuracy, since as the measured section is passed, the location of the aircraft is corrected in three coordinates: the traditionally used planned coordinates and the height values entered in this case to the surface of the measured section.

The navigation method is implemented as follows.

We will consider the implementation of the aircraft navigation method using the example of compiling the current map using three rays of radio waves located in one plane, which is at an angle to the horizon plane of the measured section.

During the movement over the measured area, the current map of the area is determined, for the preparation of which data on the measured values of the inclined range using the rays of radio waves, as well as the speed and angles of evolution of the aircraft (pitch, roll and course) are used.

In the analysis, we will use the following coordinate systems, shown in figure 1, for:

- a reference map of the terrain (large rectangle in figure 1);

- square of uncertainty (square in figure 1);

- possible positions of the aircraft inside the uncertainty square at the time of the start of measurements (points in FIG. 1), and the points of the trajectory of the aircraft at which measurements are made (diamonds in figure 1).

The local coordinate system is the left rectangular Cartesian coordinate system О _r x _r y _r z _r with the origin О _r . In this case, the axes О _r x _r and О _r y _r lie in the plane of the local horizon, that is, x _r and y _r are the planned coordinates of the aircraft. Relative to the plane О _r x _r y _r determine the elevation of the terrain and the aircraft. Thus, the indicated heights are the corresponding values of the coordinate z _r . The origin of the coordinates O _{r is} chosen so that the axis O _r y _{r is} directed to the calculated point of the appearance of the aircraft over the area corresponding to the reference map. The axis O _r y _r is considered collinear with respect to the horizontal component of the calculated velocity vector of the aircraft (Fig. 1). The planned coordinate system is fixed and connected to the reference map.

In order to attach the planned coordinates to the reference map, use a discrete coordinate system. In this case, the axes N _x and N _are co-directed with the axes of the local system O _r x _r y _r (Fig. 1). Zero indices in the discrete coordinate system correspond to the lower left corner of the reference map. The estimated value of the discrete coordinates of the aircraft at the time of the start of data collection О _{r is} denoted by (n _xrЭ , n _урЭ ).

The relationship between the coordinates of the discrete and local coordinate systems is determined by expressions of the form

where Δ _E is the grid cell size of the reference card.

When determining the coordinates of the measurement points in the form of intersection points of the underlying surface and the rays of the radio waves, a coordinate system is used that is associated with the current position of the aircraft. The origin of the system (point _Oa) was placed in the current projection point trajectory of the aircraft on the plane plane coordinates. On the x axis _and the direction _and coincides with the current direction of the aircraft velocity vector.

The relationship between the coordinates of the system associated with the aircraft, and the local coordinate system is determined by the expressions

where x _rc and y _rc are the coordinates of the projection of the current position of the aircraft on the plane of the planned coordinates; α _x - the course of the aircraft at the current measurement point (the angle between the velocity vector of the aircraft and the axis O _r x _r ).

The initial data for calculations in KESN are:

- a reference map, which is an array of data on the terrain, the elements of which are the elevations of the relief at the nodes of the coordinate grid of the reference map on the plane O _r x _r y _r ;

- data determined by the angle between the rays α _{R of the} radio waves;

- measurement data, different from those obtained with the help of the rays of radio waves, arriving with each measurement result: values of the angle α _{Z of the} roll, angle α _{x of the} course, angle α _{t of} pitch, speed ν of the aircraft;

- the current map, which is a set of values of inclined ranges for all three rays received in each dimension.

The current map of the area is determined by the matrix H (n _x , n _y ) of size N _x × N _y , and the reference map is determined by the matrix H _E (n _x , n _y ) of size N _xE × N _uE . The discrete values of n _sx and n _sy correspond to the horizontal and vertical displacement of the current map relative to the reference and are counted from the lower left corner of the reference map, for which n _sx = n _sy = 0.

In the proposed method, a differential-difference algorithm for processing multipath measurements is used, which we will consider using the example of a three-beam KESN. Rays of radio waves emit sequentially in the following order: the first is the central beam (in the direction of movement of the aircraft), the second is the left beam and the third is the right beam relative to the central beam.

The algorithm used consists in determining the difference in measurements of the left and central rays, the right and central rays of the current measurement, as well as in calculating the difference in measurements of the central ray in the current measurement and in the previous one. Using the reference map for each hypothesis, the position of the coordinates at each point is determined, for which the elevation of the terrain in the measured area is calculated.

The proximity indicator of the data will be in the form

where the following indexation is used to indicate the measurement differences: the upper index 12 means subtracting the measurement result for the first ray from the measurement results on the left, and the upper index 32 means subtracting the measurement result for the first ray from the result for the right index, the upper index 22 means the result of measuring the height value for the first ray - in this and in the previous dimension.

Data processing for each measurement is as follows.

Based on the obtained data on inclined ranges, as well as on evolution angles, the coordinates of the measurement points in the coordinate system associated with the aircraft are calculated.

The local coordinates of the projection of the point of the trajectory of the aircraft on the plane of the planned coordinates are calculated.

For each hypothesis, that is, for all possible positions of the aircraft inside the uncertainty square, one term of the proximity indicator is calculated.

Upon completion of all measurements, an extremum of the proximity indicator is searched.

Calculate the height of the aircraft in the coordinates of the measured area.

Give corrections to the coordinates of the location of the aircraft (according to the planned coordinates and altitudes).

Consider this algorithm in detail.

The measured values of the inclined ranges to the underlying surface elements D _j (j∈ [1, 3] is the number of the radio wave beam) determine the coordinates of the measurement points in the coordinate system associated with the aircraft, as well as the measured values of the elevation height H _j .

According to figure 2 we get the system of equations for each ray j in the following form

The obtained data on the speed and angles of evolution determine the coordinates of the projection of the point of the trajectory of the aircraft on the plane of the planned coordinates.

For the first measurement, these coordinates are considered to be zero (i.e., the position of the aircraft at the first measurement coincides with the beginning Systems _r x _r y _r coordinate)

The local coordinates of the aircraft during the following measurements are calculated by the recurrence relations

where T _s is the period of arrival of the measured data, i = 1, 2, ... is the number of the current measurement.

Knowing the coordinates of the measurement points in the coordinate system associated with the aircraft (O _a x _a y _a ), and the local coordinates of the origin O _a , determine the coordinates of the measurement points in the local coordinate system

Enumeration of hypotheses is as follows. For each of the possible positions of the aircraft within the uncertainty square, the coordinates (in a discrete coordinate system) of the measurement points calculated earlier in the local coordinate system are calculated. For this, the point О _{r is} placed alternately in the nodes of the coordinate grid inside the uncertainty square and the calculation of the proximity indicator of the data is performed. The coordinates of the measurement points in a discrete coordinate system are defined as

where n _hx and n _hy are the offsets of the point O _r for various hypotheses, defined in the number of grid nodes of the reference map.

The proximity indicator of data P (n _hx , n _hy ) for this case has the form

- разность измеренных в k-м измерении значений высоты по первому и левому лучам;

- разность измеренных в k-м измерении значений высоты по первому и правому лучам;

- разность значений высоты измеренных в k-м и (k-1)-м измерениях;

- разность определенных для некоторой гипотезы (для определенного значения n_hx и n_hy) значений высоты по данным эталонной карты на k-м измерении по первому и левому лучам;

- разность определенных для некоторой гипотезы значений высоты по данным эталонной карты на k-м измерении по первому и правому лучам;

- разность определенных для некоторой гипотезы значений высоты по данным эталонной карты на k-м и (k-1)-м измерениях по первому лучу.Here n _hx and n _hy are the displacements of the point О _r for various hypotheses; K is the number of measurements;

- the difference of the height values measured in the k-th measurement on the first and left rays;

- the difference of the height values measured in the k-th measurement on the first and right rays;

- the difference in height values measured in the k-th and (k-1) -th dimensions;

- the difference of the height values determined for a certain hypothesis (for a specific value of n _hx and n _hy ) according to the data of the reference map in the kth dimension according to the first and left rays;

- the difference of the height values determined for a certain hypothesis according to the data of the reference map in the kth dimension according to the first and right rays;

- the difference of the height values determined for a certain hypothesis according to the data of the reference map on the k-th and (k-1) -th measurements on the first ray.

Upon completion of all measurements, a global extremum of the data proximity indicator P (n _hx , n _hy ) is searched for and corrections to the coordinates of the aircraft’s location are determined by the planned coordinates.

To determine the corrections to the coordinates of the location of the aircraft by the third coordinate (height), we find the flight altitude of the aircraft at the time of determining the corrections of the location of the aircraft in the planned coordinates of the measuring section. To determine the height adjustment, it is required to know the value of the aircraft height above the underlying relief at the same time.

In the case when the roll and pitch angles are equal to α _t = 0, α _z = 0, that is, when the first beam is directed vertically downward, the measured height will be equal to the inclined distance to the surface of the measured section obtained when measuring from the first beam at the time the corrections are determined aircraft locations in the planned coordinates of the measured area.

In the general case, when α _t ≠ 0 and α _z ≠ 0, the measured height differs from the result of measuring the slant range to the surface of the measuring section obtained by measuring the first beam.

We assume (Fig. 3) that the aircraft is located at point O, and the angle between the first ray of OH ₁ and the perpendicular to the surface of OH ₀ is Q. Note that in the general case OH _j = D _j . For example, for the first beam, according to figure 2, OH ₁ = D ₁ .

As a result, we obtain the expression

Given the known heights of the points H ₁ and H _{0 of the} reference map in the planned coordinates of the measured area and using interpolation methods, we calculate the elevation of the relief at these points: H ₁ L ₁ and H ₀ L ₀ .

The difference h _e (Fig. 3), equal to h _e = Н ₁ L ₁ -H ₀ L ₀ , added to the value of OH _R , will give the desired aircraft height above the surface of the measuring section

Thus, this aircraft navigation method has significant differences from the known navigation methods, since during the movement of the aircraft over the measuring section, it is possible to determine the location corrections of the aircraft in addition to the planned coordinates, also in height, that is, increased accuracy of the control of the aircraft’s movement is realized, since the corrections are determined by all three coordinates and give correction signals for the location of the aircraft, respectively, in three coordinates, which was not previously.

The considered KESN algorithm can be implemented by calculating the differences of the measurement results for several rays of radio waves.

This KESN algorithm allows the correction of the location of the aircraft after several measurements and can significantly reduce the time required to perform the correction of the location of the aircraft when moving over the measured area.

It is important to note that the considered aircraft navigation method with the proposed algorithm retains its positive properties with a different number of radio waves and ensures operability for three and more radio waves. The number of used rays of radio waves is determined only by the time during which the measurement of the location of the aircraft when moving above the measured surface area is provided.

The use of a multi-beam (the number of rays of radio waves is at least three) the compilation of the current map of the area allows for the greatest coverage of the measured surface area with a minimum width of the rays of the radio waves and the greatest energy potential, which increases the accuracy of determining the range to individual points on the surface and, accordingly, increases the accuracy of compiling the current map.

Thus, the method of navigation of aircraft has a number of significant advantages over analog and prototype.

LITERATURE

1. Beloglazov I.N., Dzhangava G.I., Chigin G.P. Fundamentals of navigation through geophysical fields. - M .: Nauka, 1985 .-- 328 S. (S.10-11, 19-22, 25-34).

2. Rzhevkin V.A. Autonomous navigation on terrain maps // Foreign Radio Electronics. - 1981. - N10. - S. 3-28.

3. RF patent 2284544, IPC G01S 5/02, G01C 21/20. Aircraft navigation method / Khrustalev A.A., Koltsov Yu.V., Ryndyk A.G., Pluzhnikov A.D., Potapov N.N., Egorov S.N. // Inventions. - 2005. - N27 from 09/27/2006 (prototype).

Claims (1)

A method of navigating aircraft, which consists in using a reference map of the area as a priori information about the navigation field, selecting a plot of the terrain (measured area) within the reference map, compiling the current map by calculating the planned coordinates of the measured area based on measurements of slant ranges using the multipath mode measurements using radio waves emitted in the form of rays, determining the difference in the results of multipath measurements, comparing the current coordinate values th and reference maps, calculating the signal of the correction of the trajectory of movement and controlling the movement of aircraft by correcting their location, characterized in that the correction of the location of the aircraft is carried out in three coordinates of the reference map (planned coordinates and height) in the coordinates of the measuring area during the movement of aircraft over measured area, and after determining the location of the aircraft in the planned coordinates of the measured area calculate the height of the aircraft in measured area coordinates at the point of location of aircraft in the planned coordinates of the measured area as the sum of the height, which is the value of the measured oblique range, multiplied by the cosine of the angle of inclination of the beam relative to the perpendicular to the surface of the measured area, and the correction determined by the reference map, which is the difference in altitude the relief of the measured area at the point of determination of the inclined range and the point located on the line of the perpendicular to the surface of the measured area.

Images