1. An air pocket positioning measurement method is characterized in that: comprises the following steps

S100, arranging a plurality of knocking points (1) and a plurality of sound pickups (2) on the outer side of the bottom of the inverted ship body (4);

s200, knocking each knocking point (1) one by one;

s300, collecting a sound signal and a resonance echo signal generated by knocking each time;

s400, respectively carrying out decoupling operation on the sound signal and the resonance echo signal to obtain a resonance frequency section; the resonance frequency section comprises time domain signals and resonance frequencies which are arranged in an increasing order of the time domain signals;

s500, obtaining a two-dimensional space position of the air pocket (5) according to the resonance frequency section;

and S600, obtaining the volume of the air pocket (5) according to the resonance frequency section.

2. The cavitation-positioning measurement method as recited in claim 1, wherein: the sound signal and the resonant echo signal are both analog signals.

3. The cavitation-positioning measurement method as recited in claim 2, wherein: s400 specifically includes the following steps:

s410, converting the sound signal into a digital signal; converting the resonance echo signal into a digital signal;

s420, converting the sound signal converted into the digital signal from a time domain into a frequency domain; converting the resonant echo signal converted into the digital signal from a time domain to a frequency domain;

and S430, decoupling the sound signal and the resonance echo signal in the frequency domain to obtain the resonance frequency section.

4. The cavitation-positioning measurement method as recited in claim 3, wherein: s500 specifically includes the following steps:

s510, convolving the resonance frequency in the resonance frequency section with the time domain signal to obtain the time sequence of the resonance frequency;

s520, multiplying the time sequence by the propagation speed of sound in the air to obtain the two-dimensional space position of the air pocket (5).

5. The cavitation-positioning measurement method as recited in claim 4, wherein: s600 specifically includes the following steps:

s610, acquiring a resonance peak value of the resonance frequency section;

and S620, inputting the resonance peak value into a trained neural network, and identifying to obtain the volume of the air pocket (5).

6. The cavitation-positioning measurement method as recited in claim 5, wherein: the trained neural network is trained by pre-collected air pockets (5) as samples.

7. The cavitation-positioning measurement method as recited in claim 6, wherein: converting the sound signal converted into the digital signal from the time domain into the frequency domain by fourier transform in S420;

in S420, the resonant echo signal converted into the digital signal is converted from the time domain to the frequency domain by fourier transform.

Background

The overturning of the ship body means that the whole or part of the ship is overturned in water to cause an accident in a form of 'back-off'; when the ship body is overturned, people in the ship often can not evacuate in time, so rescue is needed.

The existing mainstream ship body overturning rescue method is to mobilize a large amount of rescue force to search for manpower in a large range, specifically, a large amount of rescuers are dispatched to submerge into the water to search for the rescue force so as to be familiar with the structure of the underwater ship body, then the places where survivors possibly exist are judged, then exploration is carried out on the judged places, and finally whether producers exist or not is determined.

The defects of the prior art are as follows:

1. as the rescue workers need to spend a large amount of time searching underwater to be familiar with the underwater ship structure, the blindness of the determination process of the rescue target is large, the rescue progress speed is slow, and the gold rescue window is easily missed;

2. as the rescue workers are not familiar with the underwater environment and the ship structure, the rescue workers can be brought with greater potential safety hazard;

3. because the prior art completely depends on manual exploration and experience, the prior art is easily influenced by environmental factors such as water depth, visibility, water temperature and the like, and effective rescue cannot be implemented in severe environment;

4. the rescue cost is high due to the fact that a large number of rescuers, related auxiliary personnel and related facilities need to be mobilized.

On the other hand, at present, no research or application for air cavity detection rescue of a overturned ship body exists. Air pockets are one of the requirements for survivors to exist once a hull overturning accident occurs. Therefore, if the position and the volume of the air pocket can be detected, the search and rescue accuracy can be greatly improved, the search and rescue time can be greatly shortened, and the search and rescue difficulty can be reduced.

Disclosure of Invention

The invention aims to solve the problems and provides an air pocket positioning and measuring method, which aims to quickly and accurately position the position of an air pocket in a turnover ship body through a technical means and calculate the size of the air pocket, so that a great amount of time is saved for assisting underwater rescue work, and the success rate of rescue is also improved.

In order to solve the problems, the technical scheme provided by the invention is as follows:

an air pocket positioning measurement method is characterized in that: comprises the following steps

S100, arranging a plurality of knocking points and a plurality of sound pickups outside the bottom of the reversed ship body;

s200, knocking each knocking point one by one;

s300, collecting a sound signal and a resonance echo signal generated by knocking each time;

s400, respectively carrying out decoupling operation on the sound signal and the resonance echo signal to obtain a resonance frequency section; the resonance frequency section comprises time domain signals and resonance frequencies which are arranged in an increasing order of the time domain signals;

s500, obtaining a two-dimensional space position of the air pocket according to the resonance frequency section;

and S600, obtaining the volume of the air pocket according to the resonance frequency section.

Preferably, the sound signal and the resonant echo signal are both analog signals.

Preferably, S400 specifically comprises the following steps:

s410, converting the sound signal into a digital signal; converting the resonance echo signal into a digital signal;

s420, converting the sound signal converted into the digital signal from a time domain into a frequency domain; converting the resonant echo signal converted into the digital signal from a time domain to a frequency domain;

and S430, decoupling the sound signal and the resonance echo signal in the frequency domain to obtain the resonance frequency section.

Preferably, S500 specifically comprises the following steps:

s510, convolving the resonance frequency in the resonance frequency section with the time domain signal to obtain the time sequence of the resonance frequency;

s520, multiplying the time sequence by the propagation speed of sound in the air to obtain the two-dimensional space position of the air pocket.

Preferably, S600 specifically comprises the following steps:

s610, acquiring a resonance peak value of the resonance frequency section;

and S620, inputting the resonance peak value into a trained neural network, and identifying to obtain the volume of the air pocket.

Preferably, the trained neural network is trained by pre-collected air pockets as samples.

Preferably, in S420, the sound signal converted into the digital signal is converted from the time domain to the frequency domain by fourier transform;

in S420, the resonant echo signal converted into the digital signal is converted from the time domain to the frequency domain by fourier transform.

Compared with the prior art, the invention has the following advantages:

1. because the invention adopts the collection of the sound signal and the resonance echo signal, and then obtains the position of the air cavity in the overturning ship body through calculation, compared with the prior art, the speed of positioning the position of the air cavity is extremely high, and the accuracy rate is extremely high;

2. because the sound pickup is adopted to collect the sound signal and the resonance echo signal, manual searching is not needed, compared with the prior art, the labor cost is greatly saved, and the working safety potential of search and rescue personnel is greatly reduced;

3. because the invention adopts the collected sound signal and the resonance echo signal, and then obtains the position of the air pocket in the overturning ship body by calculation, compared with the prior art, the invention is not influenced by environmental factors such as water depth, visibility, water temperature and the like, and can implement effective rescue even in a severe environment.

Drawings

FIG. 1 is a schematic flow diagram of a cavitation positioning measurement method according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an apparatus according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a signal transmission process of an acoustic signal on a two-dimensional plane according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating an input-output relationship of a neural network according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a data and signal acquisition method according to an embodiment of the present invention.

Wherein: 1. knocking point, 2 sound pick-up, 3 spectrum analyzer, 4 hull, 5 air pocket.

Detailed Description

The present invention is further illustrated by the following examples, which are intended to be purely exemplary and are not intended to limit the scope of the invention, as various equivalent modifications of the invention will occur to those skilled in the art upon reading the present disclosure and fall within the scope of the appended claims.

It should be noted that the present embodiment is based on 1 air pocket.

As shown in fig. 1, a cavitation localization measurement method is characterized in that: comprises the following steps:

s100, arranging 3 knocking points 1 and 2 sound pickups 2 on the outer side of the bottom of a reversed ship body 4;

in this embodiment, the arrangement of the tapping point 1 and the sound pickup 2 is as shown in fig. 2;

s200, knocking the knocking point 1 one by one;

it should be noted that, in order to make the air cavity positioning result more accurate, a plurality of sound pickups 2 can be placed at one end of the ship body 4, different knocking points 1 are selected to perform knocking at other places of the ship body 4, and the result of each time is verified;

it should be noted that in order to facilitate reliability of neural network training and data validity, the tapping point and the microphone should be placed on the same side of the overturning hull.

S300, collecting a sound signal and a resonance echo signal generated by knocking each time through a sound pickup 2 which is arranged; the sound signal and the resonance echo signal are analog signals.

The analog signal is a signal in which the information parameter appears as a continuous signal in a given range, and has little practical significance in practical application problems, so that the analog signal needs to be converted into a digital signal in which independent variables are discrete and dependent variables are also discrete, and the resistance to the interference of the material per se and the environmental interference is much stronger than that of the analog signal.

In this embodiment, the signal transmission process of the sound signal on the two-dimensional plane is shown in fig. 3;

s400, performing decoupling operation on the sound signal and the resonance echo signal respectively by utilizing Fourier transform to obtain a resonance frequency section, wherein the Fourier transform is completed by a spectrum analyzer 3 in the graph 1; the resonance frequency section comprises a time domain signal and resonance frequencies which are arranged in an increasing order according to the time domain signal;

specifically, the method comprises the following steps:

s410, converting the sound signal into a digital signal; converting the resonant echo signal into a digital signal;

in this embodiment, the analog signal is quantized into a digital signal by a PCM (Pulse Code Modulation) method, that is, different amplitudes of the analog signal correspond to different binary values, for example, 8-bit encoding is adopted to quantize the analog signal into 2^8 ^ 256 orders, and 24-bit or 30-bit encoding is usually adopted in practical use;

it should be further noted that, in the practical application of the present invention, the PCM is not the only choice, and the present embodiment does not mean that the method of the number of the mold revolutions is limited to the PCM only.

S420, converting the sound signal converted into the digital signal from a time domain into a frequency domain; converting the resonant echo signal converted into the digital signal from a time domain to a frequency domain;

specifically, the following method is adopted:

converting the sound signal converted into the digital signal from a time domain into a frequency domain by fourier transform; converting the resonant echo signal converted into the digital signal from a time domain to a frequency domain through Fourier transform; the Fourier formula is expressed by equation (1):

and S430, decoupling the sound signal and the resonance echo signal in the frequency domain to obtain a resonance frequency section.

It should be noted that the reason for this is that the acquired sound signal and the resonant echo signal are interacted together, and need to be distinguished by the decoupling operation, so as to obtain the single-input-control-single-output type resonant signal frequency band.

S500, obtaining a two-dimensional space position of the air pocket 5 according to the resonance frequency section;

specifically, the method comprises the following steps:

s510, convolving the resonance frequency in the resonance frequency section with the time domain signal to obtain the time sequence of the resonance frequency;

one property of the fourier transform is utilized here, namely that the product of the fourier transforms of the two functions is equal to their convolved fourier transform; this property of the fourier transform is expressed by equation (2):

F(g(x)*f(x))＝F(g(x))F(f(x)) (2)

this simplifies the handling of many problems in fourier analysis, and the time order is finally obtained by inverse fourier transformation.

S520, the time sequence is multiplied by the speed of sound propagation in air, resulting in the two-dimensional spatial position of the air pocket 5.

It should be noted that the time sequence obtained after the convolution is essentially the time difference, the resonance generation time t is obtained, and then the spatial position of the air cavity 5 is obtained according to the product of the time sequence and the sound propagation speed.

In the present embodiment, the two-dimensional spatial position of the air pocket 5 is expressed by equation (3):

wherein: v is the speed of sound propagation; (x, y) is a general indication of the coordinates of the two-dimensional position of the air pocket 5, (x)₁,y₁)、(x₂,y₂) Respectively, the coordinates of the two pickups 2 on a two-dimensional plane, at₁And Δ t₂The time difference derived for the two time sequences.

And S600, obtaining the volume of the air pocket 5 according to the resonance frequency section.

Specifically, the method comprises the following steps:

s610, acquiring a resonance peak value of a resonance frequency section;

in this embodiment, the method for obtaining the resonance peak value includes: and inputting the resonance peak value as a characteristic value into a neural network for training, and establishing the size relation with the air cavity 5 according to a calibrated relation.

And S620, inputting the resonance peak value into the trained neural network, and identifying to obtain the volume of the air pocket 5.

In this embodiment, the method for acquiring the volume of the air pocket 5 is established after the experimental trial tapping data acquisition and training are completed in advance, and the strong function of the neural network is used to establish the connection between the input and the output.

As shown in fig. 1, the data collected for the trial tapping and the data format are as follows:

TABLE 1 TAKING-gathered DATA METER

Wherein: p is the pressure of the knocking; s is the size of the air pocket; h is the immersion depth; l is the air pocket to pickup distance; f is the resonance peak.

The trained neural network is trained by pre-collecting air pockets as samples. The number of air pockets is determined by the number of wave crests in the signal acquired by the sound pick-up 2, and several air pockets are formed when the wave crests appear several times. The input-output relationship of the trained neural network is shown in fig. 4.

It should be further noted that the data and signal acquisition method involved in this embodiment is shown in fig. 5.

In the foregoing detailed description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the subject matter require more features than are expressly recited in each claim. Rather, as the following claims reflect, invention lies in less than all features of a single disclosed embodiment. Thus, the following claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. To those skilled in the art; various modifications to these embodiments will be readily apparent, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

What has been described above includes examples of one or more embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the aforementioned embodiments, but one of ordinary skill in the art may recognize that many further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. Furthermore, any use of the term "or" in the specification of the claims is intended to mean a "non-exclusive or".

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.