Submarine target acoustic imaging method based on spheric array
Technical field
The invention belongs to ultrasonic imaging technique fields, more particularly, to a kind of submarine target acoustic imaging side based on spheric array
Method.
Background technique
Submarine target imaging technique more can completely obtain clarification of objective information, have in hydrospace detection important
Effect.Currently, the technology for carrying out light imaging and electromagnetic wave imaging to target develops more mature, but these methods only limit
In land, since medium is very complicated in water, light wave and radio wave are decayed seriously in water, and propagation distance is limited, and generate
Objective image quality is poor, and image resolution ratio is low.In view of sound wave can be propagated far in water, complicated water can be overcome
Literary condition, people mostly use acoustic imaging technology to detect and identify submarine target, wherein the water based on beam-forming technology
Lower acoustic imaging technology keeps the beam direction to be formed enough by making certain processing to array element received signal each in array
Sharply, and the interference echo on other directions of decaying, beam forming process is repeated to scanning area, so that it may see to target
It surveys region to be imaged, therefore application is very extensive.However, the waters of actual complex is faced, especially there are seabed backgrounds
Or when in the strongly disturbing situation of non-imaged target to object imaging is buried, for multi-beam imaging system, beam side lobe and imaging point
The height of resolution directly affects the quality of imaging effect, thus improve wave beam performance and improve systemic resolution be underwateracoustic at
As a major issue in research.
In order to inhibit beam side lobe, the method used in the past is mainly amplitude weighting facture and Adaptive beamformer
Method, although these methods can obtain relatively low secondary lobe, while constraining secondary lobe, main lobe has more or less exhibition
Width, so that Imaging Resolution is declined, and is related to various algorithms, calculation amount is huge, or even higher to hardware requirement, so that
It is limited in practical engineering applications.Nowadays, from the aspect of array element arrangement, using unequal interval battle array and aperture apodization technology is used
The technique study for carrying out suppressed sidelobes is more and more, this method can effectively suppressed sidelobes and main lobe be substantially unaffected, realized
Journey is simple.It but in numerous researchs, is not ground deeply to the formation of basic matrix using one-dimensional linear array as research object
Study carefully, if beam-forming technology can be utilized, submarine target is imaged in using face battle array even volume array, can not only inhibit wave
Beam secondary lobe improves Imaging Resolution, and can directly acquire the three-dimensional information of target.
Summary of the invention
The present invention in view of the deficiencies of the prior art, from the point of view of array type, propose it is a kind of using spheric array into
The method of row submarine target acoustic imaging.There is the ability of self-focusing in view of spheric array, utilize the random array element in part on spheric array
Transmitting focusing wave beam, remaining array element, which is made to focus, to be received, in this way, side lobe levels can not only be reduced from the response of round trip wave beam, is improved
The contrast of imaging, and two-dimensional sphere battle array is compared to conventional one-dimensional linear array, spatial resolution with higher, in conjunction with
Phase control techniques can directly obtain the spatial information and minutia of target object three-dimensional.In addition, in order to prove proposed side
Method feasibility devises a set of submarine target image-forming detecting system, and experimental verification has been carried out to it, and system mainly includes spontaneous grinds
It is the spheric array of system, noise elimination water tank, signal generating module, power amplifier module, phase control emission module, Phased Array Receiving module, preposition
Amplification module, data acquisition module and sequence controlled computer etc..
The technical solution adopted for solving the technical problem of the present invention is:
The present invention obtains more comprehensive target signature information, utilizes two dimension in order to rebuild the 3-D image of submarine target
Face battle array combines phase control techniques to handle and optimize its wave beam, and control focus beam is scanned into entire three-dimensional space
Picture.Since spheric array has the ability of self-focusing, wave beam performance can be optimized, further increase the spatial resolution of detection, if
The spherical array of 61 array elements is counted.Beam side lobe and graing lobe can be controlled in view of the unequal spacing arrangement using array element, is being used
When spheric array carries out detection imaging to submarine target, part array element to be selected at random and makees focus emission, part array element, which is made to focus, to be received,
It realizes internal loopback function, while having achieved the effect that stochastic matrix, the production of suppressed sidelobes as far as possible in the response of one way wave beam
It is raw.For the above-mentioned spheric array for capableing of internal loopback, according to electroacoustic reciprocity principle and directive property multiplication theorem, by transmitted wave
Beam response is multiplied with wave beam response is received, so that the two secondary lobe part is cancelled out each other, so that the round trip wave beam in overall system is rung
Should on further decrease secondary lobe, enhance the acuteness of wave beam, improve image quality.In order to utilize above-mentioned focus beam to underwater mesh
Mark is imaged, and image-forming detecting system is designed, and in conjunction with the data processing software and related algorithm in host computer, is extracted and is come from mesh
Fundamental frequency wave amplitude in target scatter echo signal carries out imaging to the multidimensional information of measured target and shows.
The beneficial effects of the present invention are:
1. not needing lengthy and jumbled algorithm and peripheral circuit, certain design and processing, energy are only carried out to formation and transmitting-receiving mode
Achieve the purpose that Sidelobe Suppression;
2. two-dimensional array is utilized and combines Phased array emission and receiving system, the three-dimensional information of submarine target can be directly acquired;
3. when due to spheric array radiative acoustic wave, the ability with self-focusing can further optimize wave beam;
4. the part array element work randomly selected in spheric array emits, part array element is received, and not only realizes internal loopback function,
And the condition of unequal interval battle array is met, it is capable of the generation of effective suppressed sidelobes;
5. by launching beam and receiving the neutralization effect between beam side lobe, secondary lobe is reduced in the response of round trip wave beam, is improved
Image contrast, while main lobe width is suitably reduced, improve Imaging Resolution;
6. the image-forming detecting system of design, detection efficiency is high, precision is high, easy to operate, by beam scanning, scatter echo is extracted
Submarine target is imaged in the amplitude of middle fundamental wave, is easy to be generalized in medical ultrasound image detection, to the diseases such as tumour into
Row diagnosis;
7. the data that detection system measurement obtains can be shown in real time by upper computer software, handled and be imaged output, and number
It is investigated according to the review that the later period with long-term preservation, can be conducive to.
Detailed description of the invention
The following further describes the present invention with reference to the drawings.
Fig. 1 is spheric array structural schematic diagram in the present invention;
Fig. 2 is submarine target image-forming detecting system schematic diagram of the invention;
Fig. 3 is the Steady Wave schematic diagram for taking 5 periods in reception echo of the invention;
Fig. 4 is list when carrying out two-dimensional scanning in the present invention using front end face of the focus beam of spheric array to pen core shown in Fig. 4
The comparison diagram of the response of journey focus emission wave beam and the response of round trip wave beam;
Fig. 5 is to carry out two dimension using front end face of the internal loopback function of random array elements multiple in spheric array to pen core in the present invention
The reconstructed image of Scanning Detction, the image are the two dimensional images after amplitude normalization;
Fig. 6 is that the contour of maximum amplitude decline 6dB and the actual profile of pen core front end face compare in reconstructed image in the present invention
Figure.
Specific embodiment
Imaging method and detection system of the invention are made into one below in conjunction with a specific embodiment of the invention and attached drawing
Step description, so that beneficial effects of the present invention will be further appreciated.
It is as shown in Figure 1 spheric array structural schematic diagram.A kind of spheric array of 61 array elements is devised, spheric array is by a curvature
RadiusDFor the rigid ball-crown body and several diameters of 150mmdFor 16mm, with a thickness of the small battle array of planar rondure piezoelectric ceramics of 1.5mm
Member composition, apertureLFor 160mm.Due to array element dense distribution (need to make interval between adjacent ring and in ring it is adjacent
The spacing of array element is as small as possible) and array element unequal spacing arrangement can reduce secondary lobe, ball-crown body center it is individually placed
One array element, remaining array element are closely arranged on 4 layers of annulus of the radius unequal in the center of circle coaxial (Z axis), from inside to outside, successively
6,12,18 and 24 array elements of arrangement.This arrangement mode ensure that the scrambling between array element to a certain extent, can not only
Enough reduce secondary lobe, and can guarantee highest array element utilization efficiency.
It is illustrated in figure 2 submarine target image-forming detecting system, which mainly includes signal generating module, power amplification mould
Block, pre-amplifying module, data acquisition module, ultrasound phase-control transmitting and receiving module, sequence controlled computer, size based on FPGA
For the noise elimination water tank and spheric array shown in FIG. 1 of 1m × 2m.Spheric array is loaded in noise elimination water tank, considers stochastic matrix energy
Enough enhance the acuteness of wave beam, effective suppressed sidelobes selects 32 array elements in spheric array to be focused as transmitting, foundation at random
Position, the time delay value of corresponding transmitting array element is first set in phase control emission module by sequence controlled computer, then control signal
Module generates 20 sinusoidal filler pulse signals and realizes focus emission after power amplifier module and phase control emission module, drives
Move the above-mentioned 32 common radiative acoustic waves of random array element;Using array element remaining in spheric array as receiving, equally by sequence controlled computer
The corresponding time delay value for receiving array element in Phased Array Receiving module is first set, recycles remaining array element to focus and receives, reception comes from
The scatter echo signal of focal position point, the reception signal is after pre-amplifying module is suitably filtered and amplified, by data
Acquisition module, which acquires, to be input in sequence controlled computer, then by data processing software and related algorithm, takes what is received to return
The Wave data in 5 periods extracts fundamental wave as shown in figure 3, carrying out FFT processing to it in steady-state portion in wave signal
Amplitude.It is scanned in three dimensions using the focus beam of phased system control spheric array, so that measurement is each from target object
The scattering acoustic field of point, calculates the corresponding fundamental frequency wave amplitude of each measurement point, and then reconstruct the multidimensional image of target object.
It is illustrated below with an example, it will using the beneficial effect that spheric array carries out submarine target acoustic imaging in the present invention
Further showed: with internal diameter 4.1mm, the cyclic annular pen core of outer diameter 5.5mm selects spherical surface as underwater measured target at random
32 array elements, using phased system, control focus beam in pen core as reception is focused as focus emission, remaining array element in battle array
Front end face carry out the two-dimensional scanning of arc type, the plane sizes of scanning are 10mm × 10mm, step-length 0.2mm, corresponding wave
Beam characteristic is as shown in figure 4, by the response of comparison one way focus emission wave beam and overall round trip wave beam response, discovery utilizes spheric array
Internal loopback wave beam between secondary lobe negative function, can reduce side lobe levels on overall round trip wave beam, reduce main lobe width, mention
The contrast and resolving power of height imaging, and then improve the quality of imaging.Each point returns on two-dimensional surface by calculating scanning
The fundamental frequency wave amplitude of 5 Steady Waves in wave signal, and amplitude is normalized, for output to be imaged, as a result such as Fig. 5 institute
Show.In order to evaluate the effect of reconstruction image, the contour and practical pen core front end face of maximum amplitude decline 6dB in reconstructed image are taken
Profile compare, as a result as shown in fig. 6, discovery the goodness of fit it is higher, image quality is preferable.