RU2842694C1 - High-accuracy local positioning system - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to means of navigation and manoeuvring of vehicles and various lifting mechanisms, as well as monitoring of their performance or operational parameters during operation. In the high-precision local positioning system for the vehicle navigation and manoeuvring on the paths dangerous sections (PDS), the receiving equipment system is the PDS equipment, terminal equipment in system of receiving equipment is PDS terminal equipment, and radio communication line is radio communication line “Vehicle – PDS”. PDS is the vehicle trajectory section in the vicinity of the platform located on the stationary mobile landing or cargo platform or on the ground surface.

EFFECT: increase in the vehicles and lifting mechanisms positioning accuracy, especially on the paths dangerous sections (PDS), which allows to increase the vehicles movement and handling works safety by increasing the vehicles and lifting mechanisms positioning accuracy on the paths dangerous sections.

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Description

The invention relates to means for ensuring navigation and maneuvering of vehicles and various lifting mechanisms, as well as monitoring their performance or operating parameters during operation.

Satellite systems of global positioning and navigation (GLONASS, GPS, Galileo, BeiDou) are widely used in the operation of various vehicles. In this case, a corresponding receiving device and a monitor displaying its current position and additional navigation information are installed on the vehicle, for example, patent RU 2394719 C2. The accuracy of vehicle positioning using satellite systems of global positioning and navigation is usually 1-1.5 m. However, such accuracy is not enough to ensure navigation and maneuvering of (air, water) transport and various lifting mechanisms, especially in dangerous sections of trajectories.

To improve the accuracy of positioning a moving vehicle, the information from the satellite positioning system is supplemented with data from on-board measuring devices of the current parameters of the vehicle’s movement: track angle, angular rate of turn in the horizontal plane, vector of the forward motion velocity, thrust force of the propellers, for example, patents RU 2403169 C1, RU 2406645 C1.

The next step towards increasing the accuracy of positioning a moving vehicle is the use of ground-based navigation aids - leading beacons, optical, laser or microwave, in combination with on-board receiving devices that allow calculating the coordinates of a moving land or water vehicle relative to these beacons, for example, RU 2263329 C1, RU 2411159 C1, RU 2491204 C1, US 2007236389 A1. Compared to the global navigation satellite system (GNSS), such systems allow increasing the accuracy of positioning by two orders of magnitude due to the fact that the distance from the vehicle to the ground beacon is three orders of magnitude less than to the navigation satellite. However, the listed technical solutions do not imply high-precision positioning of water vehicles, since they do not require the mandatory placement of several beacons at different heights relative to the water vehicle. If all beacons and the vehicle are located in the same plane, it is impossible to determine coordinates along the axis orthogonal to this plane.

In conditions of navigation on inland waterways, an alternative approach may be useful: a minimum set of navigation equipment is placed on watercraft, and the main parts of the high-precision positioning system are concentrated on dangerous sections of waterways, overpasses, primarily in shipping hydraulic structures, which will allow autonomous control of the parameters of vehicle movement.

Patent US 5696514 A "System for measuring location and speed using atomic clocks in moving objects and receivers" discusses a device for determining the location of a moving object in different sections of a trajectory. In this case, the transmitting system is located on the moving object for transmitting a coherent signal containing an exact frequency. The receiving system includes a plurality of receiving stations spaced apart from each other, means for determining the signal propagation time to each receiving station, means for determining the velocity component based on the frequency difference of the said transmitted coherent signal received at each receiving station and the said exact frequency, a computing system for determining the location of the moving object. The main disadvantage of the claimed system is the use of a single transmitting station on board the moving object, which does not allow 3D positioning of the moving object for its navigation and maneuvering in dangerous sections of the trajectory.

The prototype is a system for high-precision local 3D positioning of watercraft for navigation and maneuvering in dangerous sections of inland waterways, which includes a set of onboard equipment, which includes four onboard transmitting stations located not on the same straight line and emitting continuous unmodulated or modulated radio signals at different frequencies and synchronized by a common highly stable reference oscillation generator, onboard terminal equipment for the "board - shore" radio communication line, a set of shore equipment, including a computing unit, eight signal receiving stations spaced apart in space, located along the right and left banks of the channel at the vertices of a cube with a side equal to the width of the channel, the computing unit is additionally connected to: an automatic water level gauge in a shipping hydraulic structure, a memory unit containing an up-to-date database of digital 3D models of a watercraft and the bottom relief of a shipping hydraulic structure, as well as shore terminal equipment for a radio communication line "side - shore".

The disadvantage of using the prototype as a system for high-precision local 3D positioning of transport and various lifting mechanisms is the disruption of the system's operability when the receiving equipment complex is located in one plane and the system's focus on water transport.

The technological problem solved by the invention is the creation of a system for autonomous high-precision local positioning of vehicles and lifting mechanisms for their navigation and maneuvering in dangerous sections of trajectories, in which the receiving part of the equipment is placed on a special platform located on a fixed (landing or cargo) platform or on the earth's surface, and the on-board part of the equipment is minimal.

The technical result is an increase in the safety of maneuvering transport (air, water) and lifting mechanisms in dangerous sections of trajectories.

The specified technical result is achieved in that in a system comprising an on-board equipment complex and a receiving equipment complex interconnected by several navigation and communication radio links, in which the on-board equipment complex includes on-board transmitting stations emitting continuous unmodulated or modulated ultra-high frequency radio signals into the surrounding space, synchronized by a common highly stable reference oscillation generator, on-board terminal equipment of the radio communication link, the receiving equipment complex includes a computing unit to which signal receiving stations spaced apart in space are connected, implemented according to a superheterodyne circuit with a common heterodyne synchronized by a highly stable reference oscillation generator, a navigation information graphic display unit, terminal equipment of the radio communication link connected via a radio link to the on-board terminal equipment of the radio communication link, it is assumed that the receiving equipment complex is equipment of a dangerous section of the trajectory (DSP), the terminal equipment in the receiving equipment complex is the DSP terminal equipment, the radio communication link is a "TS - DSP" radio communication link, in the on-board equipment complex includes one transmitting station, and the OUT equipment complex includes six receiving stations, which are located on both sides of the dangerous section of the trajectory and are distributed with an offset relative to each other along the perimeters of the upper and lower bases of the cylinder, the axis of which passes in the vicinity of the OUT, the vehicle is an air or water vehicle or a lifting mechanism, and the dangerous section of its trajectory lies in the vicinity of a special site located on a stationary mobile (landing or cargo) platform or on the earth's surface.

The invention is explained by illustrations, which depict:

Fig. 1 - Structural diagram of the high-precision local positioning system;

Fig. 2 - A specific example of the system.

The structure of the high-precision local positioning system is illustrated by the diagram shown in Fig. 1.

The system contains a set of onboard equipment and a set of out-of-planet equipment, connected to each other by several radio navigation and communication lines.

The on-board equipment complex (K1) includes:

- one on-board transmitting station (1) emitting a continuous unmodulated or modulated ultra-high frequency radio signal into the surrounding space. The radiation center of the on-board transmitting station's transmitting antenna is structurally rigidly connected to the vehicle body and is a reference point on the vehicle body. Determination of the coordinates of the radiation center of the transmitting antenna on a moving vehicle or lifting mechanism is possible by determining the projections of the full velocity vector onto the directions to several, at least six, spatially spaced and not located in the same plane fixed signal receiving stations. Measurement of at least six linearly independent projections of the velocity vector is necessary for an unambiguous resolution of a system of equations that includes six independent unknown quantities: three coordinates of the reference point and three components of the full vector of its velocity. Measuring the projection of the velocity vector of a radio wave source onto the direction to the reception point consists of measuring the Doppler shift of the frequency of the received wave relative to the transmitted one. To measure the difference between these two frequencies with the required accuracy, it is necessary to maintain the transmitter frequency with the required accuracy and measure the frequency of the received signal with the highest possible accuracy. The maximum accuracy of maintaining the transmitter frequency is achieved by synchronizing with the atomic frequency and time standard (http://www.gaoran.ru/russian/lg/at%26f.html). The maximum accuracy of frequency estimation is achieved by using continuous unmodulated harmonic oscillation (https://digital.gov.ru/uploaded/files/prilozhenie-1-k-16-37-02-dop-k-normam1713.pdf#:~:text=

1.2.4%20When%20measuring%20frequency%20deviation,%20must%20be%20specified

specific measurement methodology - Appendix A, p.A.1.2, p. 10).

- Highly stable reference oscillation generator (2), connected to the on-board transmitting station (1). Oscillations of the highly stable reference oscillation generator (2) are fed to the reference input of the phase-locked loop system of the microwave generator of the on-board transmitting station, setting the required high level of stability of the frequency of the emitted signals.

- On-board terminal equipment of the radio communication line "TS - OUT" (3), connected via a radio line to the OUT terminal equipment of the radio communication line "TS - OUT" (7) and intended primarily for receiving navigation information necessary for maneuvering the vehicle, transmitted from the OUT equipment complex (K2). In terms of the technical result achieved by the invention, navigation information is understood to mean the current position of the vehicle body on the OUT and the forecast of this position for the time lag of decision-making.

The OUT (K2) equipment complex includes:

- A computing unit (4), connected by its inputs to the outputs of the signal receiving stations (5), and also connected by its outputs to the input of the unit (6) for graphically displaying navigation information (the current position of the vehicle body and the forecast of this position for the decision-making time lag) and the input of the terminal equipment of the “TS - OUT” radio communication line (9).

- No less than six signal receiving stations (5), the receiving antennas of the signal receiving stations are connected to the capital structures of the OUT, the coordinates of the centers of the receiving antennas are known and are not located in the same plane, the outputs of the signal receiving stations are connected to the inputs of the computing unit (4).

- Block (6) for graphic display of navigation information (current position of the vehicle body and forecast of this position for the time lag of decision-making), connected by its input to the output of the computing block (4).

- OUT terminal equipment of the radio communication line "TS - OUT" (7), connected by its input to the output of the computing unit (4) and connected via a radio line to the on-board terminal equipment of the radio communication line "TS - OUT" (3).

The operation of the system is illustrated by a specific example (Fig. 2). In Fig. 2 the designations are similar to those in Fig. 1. Additionally, a device (8) is introduced - a microwave generator synchronized by a highly stable reference oscillation generator - as part of the OUT equipment complex. The on-board complex uses one on-board transmitting station (1), located on the body of the vehicle or lifting mechanism. The OUT equipment complex includes six signal receiving stations (5), located on both sides of the dangerous section of the trajectory and distributed with an offset relative to each other along the perimeters of the upper and lower bases of the cylinder, the axis of which passes in the vicinity of the OUT, with the radius of the cylinder being at least 1 meter, the height of the cylinder being at least 4 meters. The onboard complex uses a continuous harmonic signal with a frequency of ƒ₁. The signal generator of the on-board transmitting station (1) is synchronized by a highly stable reference oscillation generator (2) with a relative frequency instability of 10^-11. The signal receiving stations (5) use superheterodyne type receiving devices, in which the heterodyne signal with a frequency of ƒ_L.O.is common to all receiving stations and is generated by a microwave generator, synchronized by a highly stable reference oscillation generator (8) as part of the OUT equipment complex, with a relative frequency error of 10^-11.

The system works as follows.

The vehicle operator switches on the on-board transmitting station (1) before entering the OUT for a time sufficient for the on-board transmitting station generator to enter the operating mode. By the time the vehicle enters the OUT, the on-board transmitting station (1) operates in the frequency stabilization mode with a relative instability of 10 ^-11 . The signal emitted by the on-board transmitting station (1) is simultaneously received by six signal receiving stations (5) of the shore complex. In the intermediate frequency path of each of the six receiving devices, a signal is generated with a frequency equal to the difference between the frequency of the transmitting station and the intermediate frequency ƒ _if , i.e. equal to (ƒ ₁ -ƒ _LO ), which is digitized with a sampling frequency of ƒ ₀ ≥5׃ _if . Samples from N readings of the digitized signal are transmitted to the computing unit (4).

Counts with sample number n of the transmitter signal received by the l -th receiver ( l =1, …, 6) at the reference time t _i , i= 1, …, N

where A _l is the signal amplitude,

λ= c/ ƒ ₁ - wavelength of the transmitter, c - speed of light,

r _l - the distance from the transmitter antenna to the antenna of the l- th receiver,

θ - initial phase of transmitter oscillations.

The signal spectrum is calculated

=FFT ,

the spectrum of the analytical signal is calculated

,

the analytical signal is calculated

,

the current phase of the analytical signal is calculated

.

The procedure is repeated with the sample number ( n +1), the difference in current phases is calculated with averaging over N samples

.

The phase increment of the transmitter signal received by the l -th receiver is caused by the change in the distance between them - Δ r _l during the time between the registration of samples with numbers n and n +1. In this case,

.

Based on the results of calculating the displacement of the transmitter relative to the l- th receiver, a system of equations is compiled

(U.1)

where ( x ₀ , y ₀ , z ₀ ) are the unknown coordinates of the transmitter,

(Δ _x , Δ _y , Δ _z ) - components of the unknown transmitter displacement vector,

( x _l , y _l , z _l ), l =0, …, 6 - known coordinates of the l- th receiver,

Δ _l is the measured length (with sign) of the projection of the displacement vector onto the beam from the transmitter to the receiver with number l .

For the onboard transmitting station (1), a system of six nonlinear equations with six unknowns (U.1) was obtained, which is solved by any iterative method, for example, Newton's. As an initial approximation of the coordinates and velocity of the onboard transmitting station (1) in the case of the first (at the beginning of the positioning procedure) measurement, some a priori or external data should be taken, for example, from a radar or GLONASS (GPS) data from a vehicle. Due to the low accuracy of the initial coordinates and velocity of the vehicle, the first iterative procedure may take a little longer.

After resolving the system of equations for the first measurement, the initial coordinates of the target ( x ₀ +Δ _x , y ₀ +Δ _y , z ₀ +Δ _z ) and the displacement vector (Δ _x , Δ _y , Δ _z ) according to the previous measurement are used as the initial approximation of the iteration procedure for the second and subsequent measurements. The closeness of the initial approximation to the true values of the unknown quantities will reduce the number of required iterations to one or two. Also, after resolving system (U.1), during the first measurement, in subsequent measurements it is possible to substitute into system (U.1) the known estimates of the quantity ( x ₀ +Δ _x , y ₀ +Δ _y , z ₀ +Δ _z ) found in the previous measurement instead of the unknown variables ( x ₀ , y ₀ , z ₀ ). After this, system (U.1) becomes linear with respect to the three unknowns (Δ _x , Δ _y , Δ _z ). Of the six equations, only three can be left. They should be selected based on the maximum values of the coefficients ( x _l - x ₀ ), ( y _l - y ₀ ), ( z _l - z ₀ ). After which it remains only to solve the system of three linear equations for three unknowns (Δ _x , Δ _y , Δ _z ). The new target coordinates are determined as (( x ₀ +Δ _x , y ₀ +Δ _y , z ₀ +Δ _z ).

With a large signal-to-noise ratio in the receiving device, the error in estimating the movement vector of the onboard transmitting station is determined by the relative frequency instability δƒ

,

where F = V/ λ is the Doppler frequency shift at wavelength λ at transmitter velocity V . With a signal frequency of 950-960 MHz, relative frequency instability of 10 ^-11 and velocity of 1 cm/sec, the error will be ± 1.0 cm. With a threefold increase in signal frequency, the error in estimating displacement will decrease by an order of magnitude.

The estimates of the coordinates of the radiation center of the antenna of the on-board transmitting station (1) obtained in this way are used as a reference point of the vehicle model, loaded into the computing unit (4) and displayed on the graphical display unit of the navigation information (6) of the equipment complex of the OUT system and transmitted via the radio communication line through the OUT terminal equipment of the radio communication line "TS - OUT" (7) to the on-board terminal equipment of the radio communication line "TS - OUT" (3).

The values of the projections of the vehicle's speed vector (the displacement vector during the time between the registration of samples with numbers n and n +1) obtained in addition to the current coordinates of the vehicle make it possible to predict subsequent movements of the vehicle on the OUT and, thus, to predict the occurrence of emergency situations on the OUT.

Industrial implementation of the proposed system is possible on the basis of industrially produced communication equipment, measuring instruments and computing equipment known from the general state of the art. In particular, the following are known: WO 2018109435 A1 - Projectile control system using multiple transmitters and receivers of electromagnetic waves and determining the coordinates and speed of the controlled object; US 5870056 A - Passive air-to-air positioning system determining the coordinates and speed of an active target based on the results of measuring simultaneously the Doppler frequency shift and phase shifts in an interferometer with a long base.

Of critical importance for the industrial implementation of the system are measuring instruments that ensure a positioning accuracy of about 1 cm. This is a highly stable reference oscillation generator with a relative frequency instability of no worse than 10 ^-11 . Rubidium frequency and time standards Ch1-1020/2 with a systematic relative change in the output signal frequency of 10(5) MHz over 1 day of no more than ± 2×10 ^-12 , manufactured by NPP OOO GNOMON, Russia, (https://rubikom.org/catalog/rubidievyie-opornyie-generatoryi-i-standartyi-chastotyi/standart-chastotyi-i-vremeni-rubidievyij-ch1-1020-2.html) can be used as a highly stable reference oscillation generator. Ch1-1020/2 devices can be produced in a version for use on vehicles.

Thus, the proposed invention makes it possible to increase the safety of movement of vehicles and loading and unloading operations by increasing the accuracy of positioning of vehicles and lifting mechanisms, especially in dangerous sections of trajectories.

Claims (3)

1. A high-precision local positioning system for navigation and maneuvering of vehicles (V) on dangerous sections of the trajectory, containing a set of on-board equipment and a set of receiving equipment, interconnected by several radio navigation and communication links, the set of on-board equipment includes an on-board transmitting station emitting continuous unmodulated ultra-high frequency radio signals into the surrounding space, synchronized by a highly stable reference oscillation generator, made with a relative frequency instability of no worse than 10 ^-11 , and on-board terminal equipment of the radio communication link, and the set of receiving equipment includes a computing unit, to which are connected spaced signal receiving stations, made according to a superheterodyne circuit with a common local oscillator, synchronized by a highly stable reference oscillation generator, a unit for graphically displaying navigation information, terminal equipment of the radio communication link, connected via a radio link to the on-board terminal equipment of the radio communication link, characterized in that the set of receiving equipment is equipment of a dangerous section of the trajectory (OUT), which is a section of the vehicle trajectory in the vicinity of a site located on a stationary mobile landing or cargo platform or on the earth's surface, the terminal equipment in the receiving equipment complex is the OUT terminal equipment, the radio communication line is the "TS - OUT" radio communication line. 2. The system according to paragraph 1, characterized in that the OUT equipment complex includes six receiving stations, which are located on both sides of the dangerous section of the trajectory and are distributed with an offset relative to each other along the perimeters of the upper and lower bases of the cylinder, the axis of which passes in the vicinity of the OUT. 3. The system according to paragraph 1, characterized in that the vehicle is an air or water vehicle or a lifting mechanism.