RU2527136C1 - Method of measuring depth of object using sonar - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: method includes emitting a probing signal, receiving an echo signal with a static fan, directional characteristic in the horizontal plane, performing multichannel processing on all directional characteristics, selecting a threshold in each channel, determining the starting time T_min and end time T_max of the echo signal in each spatial channel, selecting a channel having the maximum delay time of the end of the echo signal T_max and the minimum delay time of the beginning of the echo signal T_min corresponding to said channel, calculating the distance D_beg=T_min0.5S, calculating the distance at the end of the echo signal D_end=T_max0.5S, and the depth of the of the position of the beginning of the echo signal is determined using the formula $$H=\sqrt{D_{eng}^2-D_{beg}^2},$$

where H is the depth of the position of the beginning of the gas shroud; D_end is the distance corresponding to the maximum time of the end of the echo signal or the exit of the gas shroud from the pipe; D_beg is the distance corresponding to the maximum time of the beginning of the echo signal or the emergence of the gas shroud onto the surface; S is the speed of sound in the operating region.

EFFECT: enabling detection and classification of a leak source on an underwater gas pipeline and determining the location of a gas leak object.

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Description

The present invention relates to the field of sonar and is intended to measure the depth of the location of an object having a developed vertical structure, including the location of sources of hidden gas leaks from pipelines.

Currently, gas pipelines, which are laid at great distances under water, are widely used. They can be located both on the bottom of the seas, and in underwater position in a floating state at a certain depth. During operation, situations arise that can break the seal between the pipes, which will lead to the formation of an opening from which gas leakage will occur. A gas leak can be detected by reducing the pressure in the line. However, this is not always possible, since the pressure in the system depends on consumption, which is almost always random and depends on the randomness of switching on and off the sources of consumption. It is difficult to detect a gas leak from the surface of the water, since gas bubbles will be observed on the surface of the sea, the nature of which will be masked by the vibrating water mass. Gas leaks can also be detected using multi-beam echo sounders that work directly along the bottom and at the known location of the gas pipeline. (A.V. Bogorodsky, D. B. Ostrovsky. Hydroacoustic navigation and search and research facilities. St. Petersburg: Publishing House “LETI”, 2009, p. 89-113), however

this requires accurate knowledge of the position of the pipeline at the bottom, which is associated with extensive preliminary work. You can use side-scan sonars of the Hydra type (Sknarya A.V., Trusilov V.T., Sedov M.V. Use of side-scan sonars for solving the problems of shipping safety and environmental monitoring. Special equipment, No. 2, 2003) . Typically, these sonars are towed and have a detection distance of the order of hundreds of meters, which also limits the ability to monitor the status of pipelines. The fullest possibilities of using side-scan sonars for the tasks of inspecting water areas are described in the work of V.G. Tymoshenko. Development of mathematical software for the identification of underwater potentially hazardous objects recorded using sonar aids. Scientific research project “Object” HATCHES NIR 518-1. UDC 551.46.07. SPb, 2008. Concern Okeanpribor OJSC. A patent search is also presented there for all hydroacoustic means for detecting underwater potentially dangerous objects p.117-137, which showed that the available literature does not have methods for detecting the location of a gas sheet in large spaces and there are no methods for determining the depth of a leak source.

A known method for determining the depth of immersion of a target using a sonar is described in the work (A.P. Stashkevich. Acoustics of the ocean. L .: Sudostroenie, 1966, p. 263). The method includes measuring the distance to the target and the angle determined by the direction of the directivity in the vertical plane.

The well-known "Method and device for determining the depth of the underwater object"

authors SATO KAZUO and others according to patent JP 02708109 B2 dated 04.02.98, G01S 15/10 HITACYI LTD, which is based on the same principle as the previous method, but the direction is determined using scanning of the directivity in the vertical plane under radiation sounding signal narrow directivity.

The disadvantage of these methods is that it is necessary to know exactly the direction to the target, which is determined using a narrow directivity characteristic (XI) in the vertical plane. The result of evaluating the depth for an object is the value that is obtained when solving a right triangle by hypotenuse, which is determined by estimating the distance and angle determined by the direction of the directivity.

Such a procedure for determining the depth of immersion depends on the correctness of obtaining an estimate of the direction to the target, which depends on the width of the directivity in the vertical plane. The narrower the CN, the more accurately you can determine the direction to the target. Existing echo detection systems have a narrow directivity pattern in the horizontal plane and a wide directivity pattern in the vertical plane. The width of the directivity characteristic in the vertical plane is the final value and in existing systems is about 20 ° -40 ° at the level of 0.7 of the maximum.

A known immersion depth meter of an object according to the patent of the Russian Federation No. 119127 and a method for determining the depth of immersion of an object using a movable medium according to the patent of the Russian Federation No. 2350983 is known. They are based on the same principle, but in the meter according to the patent of the Russian Federation No. 119127, the heading angle to the object is additionally taken into account. The closest analogue is the method according to the patent of the Russian Federation No. 2350983, which is taken as a prototype. The method comprises emitting a sounding signal, receiving an echo signal and measuring the distance D ₁ at time t ₁ , at time t ₁ + Δt, repeat the procedure for measuring the distance to the object, determine the distance D ₂ to the object at time t ₁ + Δt, determine the speed carrier V _sob ; and the depth of immersion of the object relative to the horizon of movement of the medium is determined by the formula

, где $$H=\sqrt{D_2^2-\Delta D^2}$$

where

, где $$\Delta D=(D_{\mathrm{one}}^2-D_2^2-V^2\Delta t^2)/2V\Delta t$$

where

D ₁ - distance to the object at time t ₁ ,

D ₂ - distance to the object at time t ₁ + Δt,

h _rad - the depth of immersion of the radiator,

- скорость перемещения излучателя. $$V_{\mathrm{from}\mathrm{about}b}^2$$

- the speed of the emitter.

This method is intended to determine the immersion depth of a stationary local object.

If the pipeline is not tight, gas escapes, which forms a veil of bubbles. When the sonar is working, it will be possible to obtain an echo from a veil of bubbles, which is formed when the bubbles move from depth to surface. Such a reflector has a well-developed vertical structure, since the bubbles rise vertically and increase in volume, which leads to the expansion of the gas cloud at the surface. Since this object has a large extent in the vertical and horizontal plane, the error in estimating the depth significantly increases, or the inability to obtain an estimate of the depth by known methods.

, вычисляется дистанции по окончанию эхосигнала, $${Д}_{нач}=T_{макс}\cdot \mathrm{0,5}C$$

, а глубину местоположения начала эхосигнала определяется по формуле $$H=\sqrt{{Д}_{оконч.}^2-{Д}_{нач.}^2}$$

, гдеThis drawback is eliminated by the fact that new features are additionally introduced into the known method of measuring the depth of immersion, containing the sound of the probe signal, receiving the echo signal and measuring the distance, namely, the reception of echo signals is carried out by a static fan of directivity in the horizontal plane, having a directivity in the vertical plane of about 40 °, multi-channel processing is performed according to all directivity characteristics, a threshold is selected in each channel, an echo signal is detected, exceeding the last threshold in each channel, the start time T _min and the end time T _max echo signal in each spatial channel are determined, the channel with the maximum delay time T _max and the corresponding T _min minimum delay time is selected, calculated $$D_{n\mathrm{but}h}=T_{m\mathrm{and}n}\cdot 0.5C$$

, the distance is calculated at the end of the echo, $$D_{n\mathrm{but}h}=T_{m\mathrm{but}\mathrm{to}\mathrm{from}}\cdot 0.5C$$

, and the depth of the location of the beginning of the echo signal is determined by the formula $$H=\sqrt{D_{\mathrm{about}\mathrm{to}\mathrm{about}nh.}^2-D_{n\mathrm{but}h.}^2}$$

where

H is the depth of the location of the beginning of the gas sheet;

D _{is over} - the distance corresponding to the maximum closure time of the echo signal or output from shroud gas conduit;

D _beg - the distance corresponding to the minimum time of the beginning of the echo signal or exit of the gas sheet to the surface;

C is the speed of sound propagation in the area of work.

The technical result of the proposed method is to increase the accuracy of determining the depth of the beginning of the echo signal from a vertically distributed veil of bubbles, which corresponds to the location of the source of violation of the tightness of the gas pipeline.

Let us explain the achievement of the specified technical result and the essence of the proposed technical solution.

American experts conducted acoustic studies and obtained data that acoustic energy is well reflected not only by metal and rock objects, but by gas bubbles that can be created in wake jets when a surface ship moves. In the monograph Physical Foundations of Underwater Acoustics / Ed. Myasishcheva V.I. M .: Sov Radio, 1955, p. 604, issues of reflection of acoustic energy from individual bubbles and from a veil of bubbles are considered. The paper indicates that the equivalent radius of the reflector, consisting of a veil of bubbles, will depend on their size. When the radiation frequency coincides with the resonant frequency of the bubble, the echo signal increases sharply. The size of the bubbles depends on the depth of their location, since the pressure at the installation site of the gas pipeline is large, then the diameter of the bubble will be small, as it will be compressed by hydrostatic pressure and the spatial extent will be small. As you ascend, the diameter of the bubble will increase and the size of the bubble cloud will also increase in space.

On this basis, fish-finding sonars have been developed that detect echo signals reflected from swimming bladders of fish, both single and their clusters. E.V. Shishkova. Physical foundations of field acoustics. M., 1977. Known sonar designed to search and detect the accumulation of fish schools, considered in the work of Yu.S. Kobyakov, N.N. Kudryavtsev V.I. Tymoshenko. Design of sonar fishing equipment. L .: Shipbuilding, 1986, p. 5-27.

In our case, one should proceed from several obvious premises: the source of gas output is located on the pipe, the gas rises only upward and its volume increases due to expansion up to the surface, therefore the gas sheet is located vertically, and when the bubbles rise, their size increases. The presence of the pipeline does not preclude the receipt of an echo from the pipe body, since the pipe is a hollow space filled with gas, the density of which differs from the density of water.

To detect and classify a bubble sheet, it is necessary to use a conventional sonar containing a receiving and emitting antenna, a switch, a probe signal generator and a static fan of directional characteristics during reception. Since the probe signal propagates in an aqueous medium according to a spherical law, when a probe signal is emitted from a surface ship in the horizontal direction, acoustic energy will propagate, expanding in the selected direction. The first echo will come from the part of the bubble sheet that has already reached the surface, since the spatial width of the bubble sheet at the surface is maximum. The last echo will come from that part of the veil of bubbles that is at the beginning of the exit from the pipeline. Radiation is produced in the horizontal direction with a broadly directed characteristic (A.V. Bogorodsky, D. B. Ostrovsky. Hydroacoustic navigation and search and research tools. St. Petersburg: Publishing House “LETI”, 2009, p. 192.). The echo signal is received by a static fan of directivity characteristics, each of whose characteristics has a narrow directivity in the horizontal plane and a wide directivity in the vertical plane with a solution of the order of 40 ° -50 ° .. (ibid. P.172-178.). Processing of the received echo occurs autonomously and independently in each directional characteristic. In each directional characteristic, an echo signal is detected, a measurement of the amplitude of the echo signal and the moment the echo starts and the moment the echo ends. Since the veil of bubbles is continuous all the way to the surface and expands near the surface, the echo signal will be a continuous time function where the beginning of the echo signal at the surface and the end of the echo signal at the bottom will be clearly observed. Such a temporary function will be observed in two or three adjacent spatial horizontal channels if the spatial channels of the static fan of directivity characteristics overlap and the width of the gas cloud expands at the surface. Therefore, it is necessary to ensure the detection of the echo in adjacent directivity characteristics, the measurement of the moment of the beginning of the echo reflected from the veil of bubbles, the moment of the end of the echo reflected from the veil of bubbles in the adjacent directivity. When the characteristics overlap, an echo signal with a maximum duration from the beginning of the echo signal at the source to the end of the echo signal at the surface will be observed in one characteristic, and in the neighboring characteristic, only the part of the echo signal corresponding to the upper part of the shroud. This will lead to the fact that the minimum value of the start time of the echo signal T _min will be detected and measured in one channel, and the maximum end time of the echo signal T _max will be fixed in another channel. For this, it is necessary to select a channel from the entire set of measurements for which the maximum end time of the echo signal T _max and corresponding to this channel T _min is measured. The moment of termination of the echo signal T _max will correspond to the moment of gas exit and this determines the location of the gas exit from the pipe. Calculating the minimum distance D _beginning of the delay time of the echo signal to place the gas outlet at the surface of the T _m of the selected channel and by the value of the sound velocity, which corresponds to the beginning of the echo signal, and calculating the distance D _{is finished,} the corresponding echo end, the T _max of the echo signal by the maximum delay time the same channel and the value of speed, which corresponds to the beginning of the gas outlet, you can determine the depth of the location of the source of depressurization of the pipeline in meters according to the formula:

, где $$H=\sqrt{D_{\mathrm{about}\mathrm{to}\mathrm{about}nh}^2-D_{n\mathrm{but}h}^2}$$

where

H is the depth of the location of the depressurization point;

D _end = T _max 0,5C - the maximum distance corresponding to the end of the echo signal,

D _beg = T _min 0,5С - the minimum distance corresponding to the beginning of the echo signal.

The essence of the proposed method is illustrated in figure 1, which presents a structural diagram of a sonar to determine the depth of the location of the source of the gas sheet.

Figure 1 marked

1 - antenna

2 - switch receiving transmission,

3 - master oscillator,

4 - a system for forming a static fan of directivity characteristics,

5 - processor multi-channel processing system,

6 - block selection threshold in each channel detection,

7 - unit for measuring the time of the beginning of the echo signal T _min and measuring the time of the end of the echo signal T _max. in each channel;

8 - selecting a channel in which the maximum time T _max closure echo and the corresponding value of time T _min beginning echo and calculate distances _nach D, E _{make an end}

9 - block calculating the depth of the location of the beginning of the gas sheet;

10 - display and control unit.

11 - unit for measuring the speed of sound.

Antenna 1 is connected by two-way communication with the transmission reception switch 2 and, through the system 4 of forming a static fan of directivity characteristics, is connected to the processor 5 of the multi-channel echo signal processing system, each channel of the K channels of which consists of series-connected detection block 6, selection block 6, start time measurement unit 7 T _{min of the} echo signal and the end time of the echo signal T _max , block 8 channel selection with time T _max and the corresponding time T _min and the calculation of D _start and D _end , with the first input b Lock 9 calculating the depth of the location of the beginning of the gas cover, through the two-way input of the display and control unit 10 with the input of the master oscillator 3 and then with the input of the transmission reception switch 2. The sound velocity meter 11 is connected to the second input of the processor 5 of the multi-channel echo signal processing system.

Antenna, transmit and receive switch, master oscillator are known devices and are used in the development of sonars. A.S. Kolchadantsev. Hydroacoustic stations. L .: Shipbuilding, 1982, p. 60-90. The system for forming a static fan of directional characteristics is a known device that can be formed by both analog and digital methods, for example, such as those described in the Reference book for hydroacoustics. L .: Shipbuilding, 1988, p. 18-29.

Currently, all sonar equipment is made using digital processing methods and is implemented on special processors or personal computers with appropriate software available or specially developed based on standard programming methods.

Digital processors are well-known devices that are designed to implement specific processing algorithms using hardware solutions and strict computational logic. Their use increases the speed of digital computing systems several times, and in most cases reduces hardware costs. Descriptions of special processors are given in the book Koryakin Yu.A., Smirnov S.A., Yakovlev G.V. Ship sonar equipment. St. Petersburg: Nauka, 2004, p. 281. There is also a description of sonar systems and sonars built on the basis of special processors p.296, p.328.

Issues related to digital signal processing, modulation and demodulation issues, spectral analysis, as well as the use of Matlab extension packages, which provide a consistent procedure for using the developed algorithms, are considered in A.B. Sergienko. Digital signal processing. SPb., 2011, p. 655. The sound velocity meter is a known device V. Komlyakov Shipborne means of measuring the speed of sound and modeling of acoustic fields in the ocean. St. Petersburg: Science 2003

The measurement of the depth of the location of the beginning of the formation of a gas sheet is as follows.

The control and display unit 10 generates a radiation command, which is transmitted to block 3 of the master oscillator. The master oscillator generates a probe signal of the desired duration, at the desired frequency and the required power. This signal is transmitted through the receive-transmit switch 2 to the antenna 1 and is radiated into the water. The echo signal received by antenna 1 through the receive-transmit switch 2 enters the system for generating a static fan of directivity characteristics, where the directivity characteristics of the required width are formed in the horizontal plane and in the vertical plane. The output of the system 4 is connected to the first input of the processor 5 of the multichannel echo processing system, which is a detection and measurement system, the number of channels of which is equal to the number of directivity characteristics. In each channel, there is a threshold selection unit 6 and an echo signal start time measurement unit T _min in the channel and an echo end time T _max.

In block 7, the excess of the echo amplitude over the threshold selected in block 6 is determined, the amplitude of the echo signal and the temporary position T _{min of the} beginning of the echo signal and T _max time of the end of the echo signal are measured.

The times measured in block 7 for all K - independent channels, together with the channel numbers, enter block 8 of the channel selection with the maximum echo end time T _max and the corresponding T _min minimum echo start time. Based on the measured T _max and T _min, the distance estimates of D _beginning and D _end are calculated using the measured estimate of the speed of sound by block 11. The resulting distance estimates are sent to block 9 for calculating the depth of the location of the beginning of the gas sheet, where the depth is calculated by the developed algorithm according to the above formula. The depth estimate is supplied to the display and control unit 10 and is displayed on an indicator or display. At the same time, the indicator displays the spatial channel in coordinates — the time of the processes for all channels, and the operator can verify the correctness of the selected channel and the correct measurement of times, as well as, if necessary, make measurements based on work experience.

Thus, the proposed method allows to detect the veil of a gas leak and measure the depth of the place of formation of the gas veil by hydroacoustic means at long distances, therefore, we can consider the claimed technical result achieved.

Claims (1)

A method for measuring the depth of an object with a sonar, containing radiation from a sounding signal, receiving an echo signal and measuring a distance, additionally introduced new features, namely, the echo signals are produced by a static fan of directivity in the horizontal plane, having a directivity in the vertical plane of about 40 °, multi-channel processing is performed according to all characteristics directivity, select a threshold in each channel, detect an echo signal that exceeds the threshold in each channel, measure the start times And times T _min T _max closure echo in each spatial channel, select the channel having a maximum delay time T _max closure echo and the corresponding channel minimum delay echo start T _min is calculated _nach distance D = T _min 0.5C, calculated by the distance end of _{the Finishing} echo D = T _max 0.5 C and a depth echo start position is determined by the formula $$H=\sqrt{D_{\mathrm{about}\mathrm{to}\mathrm{about}nh.}^2-D_{n\mathrm{but}h.}^2}$$

where
H is the depth of the location of the beginning of the gas sheet;
D _{is over} - the distance corresponding to the maximum closure time of the echo signal or output from the shroud gas tube;
D _beg - the distance corresponding to the minimum time of the beginning of the echo signal or exit of the gas sheet to the surface;
C is the speed of sound propagation in the area of work.