WO2017091100A1

WO2017091100A1 - Method of determining the position of a navigated object

Info

Publication number: WO2017091100A1
Application number: PCT/RU2015/000823
Authority: WO
Inventors: Виктор Васильевич ШЕБОЛКОВ; Игорь Георгиевич ДОРУХ
Original assignee: Акционерное Общество "Азовский Оптико-Механический Завод"
Priority date: 2015-11-26
Filing date: 2015-11-26
Publication date: 2017-06-01

Abstract

The invention relates to radio navigation and can be used in local navigation systems and networks for controlling the movement of mobile objects in local navigation zones. The present method is based on a high frequency harmonic signal being emitted from a navigated object and being received at several radio navigational reference points with known coordinates, wherein a second high frequency harmonic signal is additionally emitted from the navigated object, the frequency of which differs from the frequency of the first high frequency harmonic signal by a given magnitude, this signal is received at each of the radio navigational reference points together with the first signal, difference frequency signals are generated from the received signals, the signals generated are transmitted to a central processing point, where reference frequency signals are additionally generated from each of said difference frequency signals, the magnitude of the reference frequency being n times less than the difference frequency, the phase differences of the difference frequency signals arriving from different reference points are measured and recorded, as well as the phase differences of the reference frequency signals generated therefrom, upon measurement completion, the phase difference measurement results are converted into coordinates of the navigated object, taking into account the relative position of the central processing point and the radio navigational reference points.

Description

METHOD FOR DETERMINING THE LOCATION OF THE OBJECT

NAVIGATIONS

The invention relates to radio navigation and can be used in local navigation systems and networks to control the movement of mobile objects in local navigation areas.

Known protected by RF patent j \ b 2204145, class. G01 S 3/46, 2003 a method for determining the coordinates of a radiation source, based on the reception of its signal by three antennas forming orthogonal bases.

Such an action as determining the direction to the radiation source is an essential sign of the proposed method.

Also known is RF patent N_? 2013785, class G01 S 13/00, 1994, a method for determining the location of moving objects, which consists in emitting encoded signals by transmitters of objects, receiving signals at N spatially separated points, followed by relaying them to a central processing point and measuring the delays between the received signals.

Relaying signals to a central processing point is an essential feature of the proposed method.

The reason that impedes the achievement in these analogues, protected by patents of the Russian Federation, of the technical result provided by the invention, is the need to use a rather complex system of uniform time. There is a known differential-ranging method for determining the location of mobile objects, which consists in alternating radiation of a network of navigation reference points located at points in space with known coordinates, coherent harmonic signals, their reception on a mobile object, received from each reference object and calculating the coordinates of the mobile object from them [ Bakulev P.A., Sosnovsky A.A. Radar and radio navigation systems. - M .: Radio and communications, 1994, p. 21 1-214].

The measurement of the phase shifts of the signals and the calculation of the coordinates of the mobile object from them is an essential sign of the proposed method.

The reason that impedes the achievement in this analogue of the technical result provided by the invention is the need to use a high-precision scale of a single time at the navigation object and the difficulty of implementation at large distances between the reference radio navigation points and the navigation object.

The closest in technical essence to the claimed (prototype) is the reversed difference-range-finding method for determining coordinates [Kinkulkin I.E., Rubtsov V.D., Fabrik M.A. Phase method for determining coordinates. - M .: Sov.radio, 1979, p. 10-1 1, p. 97-100].

The method consists in the simultaneous emission of continuous harmonic high-frequency signals by a navigation object and a transmitter installed at a fixed point with known coordinates and the simultaneous reception of these harmonic signals at several reference radio navigation points and the formation of differential frequency signals from the received signals there.

Such actions as the emission of high-frequency harmonic signals by the navigation object and the reception of radiated high-frequency harmonic signals at reference radio navigation points with known coordinates, the formation of difference frequency signals from the received high-frequency signals there are significant features of the proposed method. The reasons that impede the achievement in the prototype method of the technical result provided by the invention are as follows.

The first reason that impedes the provision in the prototype method of the technical result provided by the invention is the need for continuous emission of the signal by a fixed transmitter. This degrades the electromagnetic compatibility of the equipment. There is a need for the simultaneous reception and transmission of two signals with close frequencies, which worsens the conditions for ensuring information security of equipment and makes it easier to suppress its operation. These circumstances reduce the noise immunity of devices that implement the method.

The second reason that impedes the achievement of the technical result provided by the invention in the prototype method is the fact that the coordinates of the stationary transmitter are always determined with some error, which ultimately leads to a decrease in the accuracy of measuring the coordinates of the navigation object.

The third reason that impedes the provision of the technical result provided by the invention in the prototype method is the small size of the space region within which it is possible to uniquely determine the coordinates of the navigation object with high accuracy. The dimensions of this region of space in the prototype method are limited by the zone in which the distances between the navigation object and each of the reference radio navigation points should differ from each other by no more than half the wavelength of the frequency signal equal to the frequency difference of the microwave signals emitted by the navigation object and the transmitter fixed at a fixed point.

The technical problem to which the invention is directed is to increase the noise immunity of devices that implement the proposed method, increase the accuracy of determining the coordinates of the navigation object and expand the area of space within which it is possible to unambiguous determination of the coordinates of the navigation object without reducing the accuracy of this definition.

To achieve the specified technical result in the known method of determining the location of the navigation object, which consists in emitting the navigation object of a high-frequency harmonic signal, receiving it at several reference radio navigation points with known coordinates, an additional second high-frequency harmonic signal is emitted from the navigation object, the frequency of which differs from the frequency of the first high-frequency harmonic signal by a given value, in each of the reference radio navigation points pr they take this signal along with the first one, form the difference frequency signals from the received signals, transmit the generated signals to the central processing point, where each of them additionally generates the signals of the scale frequency, the value of which is n times less than the difference frequency, measure and record the phase differences of the difference signals the frequencies received from different reference points, as well as the phase differences of the signals of the scale frequency generated from them, at the end of the measurements, the results of the measurements of the phase differences are recalculated You are a navigation object, taking into account the relative position of the central processing point and reference radio navigation points.

The invention is illustrated in the drawing, which shows:

- in FIG. 1 - the relative position of the navigation object and the three reference radio navigation points in a rectangular coordinate system 0XY;

- in FIG. 2 - zone of unambiguous determination of the coordinates of the navigation object in relation to these points.

The operation of the method is illustrated in figure 1, which shows a mobile navigation object (MO) located at a point with unknown coordinates Xmo and Umo, reference radio navigation points ORT1, ORT2 and ORTZ located at points with known coordinates X _\ and Y, ΧΊ and Ug and Xs and Uz, respectively, as well as the central processing point (CPO), the distances from which to the points ORT1, ORT2 and ORTZ are respectively R R2 and R3. It also shows the distances i, D ₂ , A between the navigation object and the reference radio navigation points.

For a given time interval, a signal S _M0 (t) is emitted from the navigation object in the direction of the points OPT1, OPT2 and ORTZ, which is the sum of two harmonic high-frequency signals with amplitudes A, frequencies ωι and &> and random initial phases φ and φ ₂ :

S _MO {t) = 4 [cos (fi> _j t + ψ _\ ) + cos (&> ₂ t + φ ₂ )].

The time interval during which the considered signal is emitted is selected sufficient to perform phase measurements in the central processing unit (more on this below).

The emitted MO signal is received at points ORT1, ORT2 and ORTZ, remote from the navigation object at distances A, A and A, respectively. Accepted at these points signals S _\ (t), S ₂ (t) and S ^ t) are as follows:

8 _] (ί) = Α _ι {^ [ω _ι (ί + ^) + φ _ι ] + € 03 [ω ₂ (ί + ^ -) + φ ₂ ]} -

A a

S ₂ (t) = A ₂ {cosfa {t + ^) + ^ + cos [ ₂ (t + ^) + q> ₁ \} -,

8 ₃ (ί) = Α ₂ {οο5 [ω _] (ί + ^ -) + φ _] ] + οο3 [ω ₂ (ί + ^) + φ ₂ ]}, where С = 2,9979 - 10 ⁸ m / C is the propagation velocity of radio waves in the atmosphere.

In each of the reference radio navigation points from the received signal

S _j (t) (/ = 1, 3), which is the sum of two high-frequency harmonic signals with frequencies ω ι and a> 2, form signals with a difference frequency ω =

(beat frequency):

^S OPT \ (0 = A soybean [th) _p {ί + ^) + φ _χ - φ ₂ },

BUT

^S OPT2 (0 = ™ ί {ω _ρ (ί + ^~ ) + φ _] - φ ₂ ] ^, ^s OPT3 (0 = ^A 3 ^C0S K? (t + - + φ _χ - φ ₂ ].

These signals differ in amplitudes and time delays, which are determined by the distances D _\ , Di and Z ⁾ _3, respectively. The generated differential frequency signals are transmitted through wire channels to the DSP.

Thus, the following three signals arrive in the CPU:

1) the signal received from ORT1:

where C _\ is the harmonic signal propagation velocity along the wire channel.

It differs from the signal <$ οΡΤ ΐ (amplitude and additional phase,

shift ^ω _Ρ , which is due to the passage of the distance R \ separating ORT1 and CPO.

This signal can be represented as follows:

2) the signal received from ORT2:

£ (0 = Ap ^{C0S (} * + - 7) + ^ω ρ]

It differs from the signal S _OPT2 {t) in amplitude and additional phase R ₂

the shift ^~ &> p, which is due to the passage of the distance R ₂ separating ORT2 and CPO

This signal can also be represented as: DR

where Ψι = [(φ -φ ₂ ) + ω _ρ ^ + ω _ρ - \

3) the signal received from ORTZ:

D r

5cc (0 = 4c ^s ™ [& _Р (t + -) + φ, - φ ₂ + - ω _ρ ]

It differs from the signal <$ ORTZ (amplitude and additional phase shift -τ ^ω _ρ , which is due to the passage of the distance R ₃ separating the ORTZ and the CPO.

It can also be represented as:

SZZ (*) = ^A zz ^with $ ^eo p * + Chz>

The phase difference Λψ _2] - ψ2 ^~ Ψ _{\ of the} signals S _U2 (t) nS _m (t) and the phase difference

:

D ₂ -D, R ₂ -R,

C * C

As follows from these expressions, the phase differences Λψ _ιχ and / 1 ^ ₂₃ ^{do not} depend on the initial phases of the emitted MO signals φ and φ ₂ .

The second terms in the expressions for _{Δψ 1λ} and

Δψ ₂ are independent of the spatial position of the navigation object. They represent additional phase shifts of the signal with a frequency _cp when they are transmitted from the corresponding reference points to the CPU. These phase shifts are determined by the relative position in the center of the space relative to the reference points ORT1, ORT2 and ORTZ, they can be calculated in advance and subtract from the phase differences Δψ ₂ and Λψ, measured in the CPO,. This allows you to find the phase differences of the signals with a frequency _r generated at the reference points ORT2 and ORT1 and ORT2 and ORTZ, which are necessary to find the differences of distances D ₂ -D _{ nD ₂ -D ₂ used to calculate the coordinates of the navigation object.

An unambiguous measurement of the coordinates of the navigation object is possible only in the area of space served by the radio navigation system for which the phase shifts Αψ _2] and Δ <//, _{3 of the} difference frequency signals do not go beyond the interval

. This condition is satisfied if, within the specified space region, the distances from any of its points to any of the reference radio navigation points differ by no more than half the wavelength λ _{ρ of} the difference frequency signal ω _ρ . The region of space for which this condition is fulfilled is bounded by the quadrilateral ABEF, the sides of which are the position lines AB, EF, BE and AF (figure 2), the equations of which have the following form:

, j (XX _] ) ² + (Y ~ Y _x ) ² - ^ (XX ₂ ) ² + (YY ₂ ) ² = L _x ;

^ {X-X ₂ ) ² + (Y- Y ₂ γ - {χ -χ, Ϋ + {γ- Υ, f = L ₂ , where the parameter L \ is equal to - ^ - for the AF line and ( ^_ ^) Д ^{for the} line BE, and the parameter Li is equal for the line EF.

To expand the region of unambiguous determination of coordinates, it is necessary to increase the value of R _p and, therefore, reduce the value of the difference frequency ω _ρ .

It should be noted that the reduction of the difference frequency ω by itself, for example, by converging the frequencies ω _χ and ω _{2 of} high-frequency harmonic signals with a constant error of phase measurements automatically leads to a decrease in the accuracy of measuring distance differences and, as a consequence, to a decrease in the accuracy of measuring coordinates.

To prevent a decrease in the accuracy of distance differences, phase measurements in the proposed method are carried out at two frequencies: directly at the difference ω _ρ and additionally formed in the CPO scale a> _n = o _p / n, the frequency of which is selected to be n times less than ω _ρ . Scale frequency signals are generated for each of the signals S _m (f), S _U2 (t) and S _ui (i) received at the central processing point from the points OPT1, OPT2 and ORTZ.

Considering that phase measurements at a frequency ω _{ρ are} unique only in that region of space for which the distance differences that correspond to the signals S _l (t), Sy ₂ (t) and S _u , (t do not exceed half the wavelength of the signal of the difference frequency, the actual phase differences Α ψ for any two signals at a frequency of o _p is determined by the formulas:

Αψ ^φ = Αψ _ρ + 2πΚ, where Α _ρ and Αψ _η are the phase differences of the signals measured in the CPO at frequencies o _p and ω _η - int (x) is the integer part of the argument x.

The coefficient k and the actual phase difference Αψ are calculated for the signals of each of the ORT pairs from the phase differences Αψ _ρ and Λψ _η measured in the CPO.

Below is the algorithm for converting the results of phase measurements into the coordinates of the navigation object. This algorithm is applicable for local navigation systems when it is permissible to neglect the sphericity of the Earth, and the propagation speed of radio waves in the coverage area of the navigation system can be considered constant.

The initial data for the calculation are:

- the phase difference _{Δψ η1 χ of the} signals measured in the CPO at a frequency ω _η for the radio navigation points ORT1 and ORT2;

- the phase difference _{Δψ η23 of the} signals measured in the CPO at a frequency ω _η for the radio navigation points ORT2 and ORTZ;

- the phase difference Δί // _{ρ21 of the} signals measured in the CPO at a frequency ω _ό for the radio navigation points ORT1 and ORT2;

- the phase difference Δ ^ _{ρ23 of the} signals measured in the DPC at the frequency ω _ό for the radio navigation points ORT2 and ORTZ.

In addition, the following constants are used in the calculation:

- the value of the first high frequency co,;

- the value of the second high frequency O ⁾ ₂ ;

- the propagation velocity of radio waves in the atmosphere C;

- the propagation speed of the radio signal through the wired channel C _\ is the distance R21 between the second ORT2 and the first ORT1 radio navigation aids;

- the distance R ₂ 3 between the third ORTZ and the second ORT2 reference radio navigation points;

- the distances R ,, R ₂ and R ₃ between the CPO and ORT1, ORT2 and ORTZ, respectively;

- the coefficient n of the excess of the differential frequency over the scale. The calculation procedure is as follows.

1. The difference ω = is calculated. frequency.

2. Calculate the phase difference of the signals of the difference frequency ω _ρ when they propagate from the reference radio navigation points to the CPO:

3. Calculate the values

k = int η

2π

4. The actual phase differences are calculated:

Αψ _2] = Αψ _ρ2 + ₂ 2lk -Δι // ₂₁

5. Solve the navigation problem - determine the coordinates of the navigation object:

a) calculate the differences of the distances from the navigation object to the reference points

FROM

Α0 ₂ , = ϋ ₂ -Ό, = Αψ

co _r

Here D _V D ₂ , D ₃ - the distance from the navigation object (MO) to the first

ORT1, second ORT2 and third ORTZ reference radio navigation points in accordance with figure 1; b) AC _and blood pressure normalized by the lengths of the baselines and calculate the parameter /:

^R 2 \ 1-

Μ ₂ = ^2ΔΟ -

R 21 R 23 ^R 23 1- Ad ₂ ² ₃ c) determine the constant parameters:

CI— ^ 21 'b = / Ad ₂₂ -Ad _2l , and where CC ₁ is the angle between the y axis and the base line R21; with _2b - the angle between the y axis and the baseline R ₂ 3.

d) do any of the numerical iterative methods solve the equation for calculating the angle? ₂ h between the base line R23 and the direction to the navigation object:

cos (a - β ₂₃ ) - γ cos β ₂₃ = b;

d) calculate the distance D ₂ from the point ORT2 to the navigation object

R ₂ , (\ - Ad])

2Ad ₂₃ + cos β ₁₃

f) calculate the coordinates of the navigation object in the local rectangular coordinate system, the beginning of which is located at the point ORT2:

x - D ₂ cos (a ₂₃ + β ₂₃ ),

y = D ₂ sin (a ₂₃ + β ₂₃ ).

If necessary, the coordinates of the navigation object are converted to the original rectangular coordinate system

^ MO = ₂ + X = ^ 2 ^{+ D} 2 ^COS ^(AP ⁺ β ^)>

^Υ ΜΟ = ^Υ 2 + Y = ^Υ 2 + ^D 2 sin ( ₂₃ + β ₂₃ ).

The fact that in the proposed method for measuring the phase difference is performed at two frequencies of the difference ω _ρ and the scale ω _η , the frequency of which is n times less than ω _Ρι, it can be concluded that the proposed method allows to significantly (approximately n ² times) expand the space in which it is possible to unambiguously determine the coordinates of the navigation object, in comparison with the prototype and at the same time not to impair the accuracy of their measurement.

In the proposed method, for such an extension, the frequency _cn is chosen sufficiently low (based on the size of the required coordinate determination area), and the frequency k> _{p is} sufficiently high (based on the required accuracy of their determination). For example, figure 2 shows two shaded areas of space bounded by quadrangles ABEF and GNMK, respectively, in which it is possible to uniquely determine the coordinates of the navigation object at frequencies 0 „and c _p, respectively. Quadrangle

ABEF corresponds to the frequency ⁽ _{n is} approximately five times smaller than the quadrilateral GNMK, corresponding to the frequency with _p .

In the prototype method, phase measurements are performed only at the beat frequency from the _river . In principle, it can be chosen quite low, but this will lead to a decrease in the accuracy of coordinate measurement, which is already reduced due to an error in determining the coordinates of a fixed transmitter.

In the proposed method, phase measurements are carried out not only at a frequency with _p , but also at a frequency with _p , which is n times lower than _p . In this case, phase measurements at a frequency ω _η are used only to eliminate the ambiguity of phase measurements, and to solve the navigation problem, more accurate calculated values of the actual phase differences are used

Δ ψ ^Φ = Δ ψ _p + 2zhk at a frequency with _p . Compared with the prototype, the accuracy of determining the coordinates in the proposed method does not decrease, but increases due to the exclusion of the error in determining the coordinates of a fixed transmitter.

The proposed method does not require continuous radiation of the second high-frequency signal, which eliminates the associated with this transmitter reduction in noise immunity of devices that implement the method.

The technical implementation of the method does not cause difficulties.

As an example of implementation, we consider the implementation of the proposed method for constructing a local navigation system for controlling traffic in high-risk areas where high-precision location of high-speed moving objects is required: on critical sections of their movement paths (for example, when approaching switch points on railroad tracks, near steep closed turns of highways). For the implementation of the system, a frequency range of 1200-1400 MHz can be selected. The coverage area of the local navigation system5 may be several hundred meters. The formation of two harmonic signals (primary and secondary) at the navigation object can be implemented on the basis of two frequency synthesizers synchronized by a common reference oscillator and adder. As frequency synthesizers, for example, ADF4360-5 type microcircuits can be used, in which it is possible to change the frequency by supplying the appropriate digital codes to the control inputs and which allow generating two highly stable harmonic signals with a frequency spacing from (0.1 - 100) MHz, as a reference oscillator, a thermally stabilized quartz oscillator type NT3225SA.

To receive harmonic signals at reference radio navigation points, you can use integrated microwave amplifiers - microcircuit type SPF5122Z. As a node for generating the differential frequency signal, you can use a mixer on the BFP620 transistor, the load of which is a low-pass filter with a cut-off frequency of 10 MHz.

The transmission of differential frequency signals from the reference radio navigation points to the central processing point can be realized via wired channels, or via radio channels with frequency separation.

The amplitude of the signals received at the central processing center is normalized by amplitude limiting the received differential frequency signals using AD8309 logarithmic amplifiers.

The generation of signals of the scale frequency is realized by dividing the frequency of the difference frequency signals, for example, using frequency dividers on K561IE20 or 561IE20 microcircuits. The measurement of the phase difference of the signals of the difference frequency in the Central receiving point can be implemented using a phase detector on the chip SYPD-1.

Analog signals from the output of the phase detector are fed through analog-to-digital converters to the input ports of the STM type microprocessor, which implements the solution of the navigation problem according to the above algorithm.

The method can be used to build tonal navigation systems for controlling traffic in high-risk areas where high-precision location of high-speed vehicles on critical sections of their tracks is required (for example, when approaching switch points on railway tracks, near sharp closed turns of automobile tracks).

Claims

CLAIM

A method for determining the location of a navigation object, which consists in emitting a high-frequency harmonic signal by the navigation object, receiving it at several reference radio navigation points with known coordinates, characterized in that the second high-frequency harmonic signal, the frequency of which differs from the frequency of the first high-frequency harmonic signal, is radiated from the navigation object a given value, in each of the reference radio navigation points receive this signal along with the first, forming comfort from the received signals, signals of the difference frequency, transmit the generated signals to the central processing point, where each of them additionally generate signals of the scale frequency, the value of which is n times less than the difference frequency, measure and record the phase differences of the signals of the difference frequency, received from different reference points , as well as the phase differences of the signals of the scale frequency generated from them, at the end of the measurements, the results of the measurements of the phase differences are converted into the coordinates of the navigation object taking into account the mutual position of the central point of navigation processing and the reference points.