CN117872394A - Target micro Doppler frequency shift imaging system - Google Patents
Target micro Doppler frequency shift imaging system Download PDFInfo
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- CN117872394A CN117872394A CN202311799477.6A CN202311799477A CN117872394A CN 117872394 A CN117872394 A CN 117872394A CN 202311799477 A CN202311799477 A CN 202311799477A CN 117872394 A CN117872394 A CN 117872394A
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- 238000003384 imaging method Methods 0.000 title claims abstract description 34
- 238000012545 processing Methods 0.000 claims abstract description 31
- 238000001514 detection method Methods 0.000 claims abstract description 15
- 238000010586 diagram Methods 0.000 claims abstract description 9
- 230000001427 coherent effect Effects 0.000 claims abstract description 8
- 239000013307 optical fiber Substances 0.000 claims description 10
- 230000010287 polarization Effects 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 230000003287 optical effect Effects 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 abstract description 3
- 230000000694 effects Effects 0.000 abstract description 3
- 230000000007 visual effect Effects 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 8
- 238000011160 research Methods 0.000 description 8
- 230000001788 irregular Effects 0.000 description 4
- 239000013598 vector Substances 0.000 description 4
- 230000036544 posture Effects 0.000 description 3
- 239000000835 fiber Substances 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000013500 data storage Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
Abstract
The application relates to a target micro Doppler frequency shift imaging system. The system collects micro Doppler frequency shift data of the surface of the target through a coherent detection system, designs a data processing system, draws a thermodynamic diagram image of the micro Doppler frequency shift of the surface of the target based on bin subdivision and interpolation, and realizes the visual display of three-dimensional micro Doppler information of the target. The specific scheme is as follows: and detecting the micro Doppler effect of the micro motion of the target by adopting a coherent detection system, acquiring data by using a data acquisition card, performing fast Fourier transform to acquire micro Doppler frequency shift data, calibrating position information of the acquired data points, then performing triangular surface element subdivision according to the position information of the acquisition points, performing cubic interpolation operation on the subdivided triangular surface elements, and calculating the micro Doppler frequency shift estimated value and the change trend of the interpolation points. Combining the calculation result with the position information, drawing a target surface micro Doppler frequency shift thermodynamic diagram, and intuitively displaying the integral characteristic of micro Doppler frequency shift generated by target micro motion.
Description
Technical Field
The application relates to the technical field of target imaging, in particular to a system for imaging by adopting a surface bin subdivision and interpolation method based on target micro Doppler frequency shift.
Background
In recent years, due to the continuous development of technical means for identifying and counteridentifying targets, the conventional information of the targets cannot meet the application requirements, and the micro-doppler effect introduced by micro-motion of the targets has become a main research direction for detecting the motion details of the targets. At present, main researches at home and abroad focus on time-frequency analysis of target micro Doppler signals, and lack of research on expansion application of target overall micro Doppler information in the technical fields of target motion characteristic research and target identification.
Disclosure of Invention
In view of this, the implementation of the application provides a target micro-doppler shift imaging system, which can perform interpolation processing on detected micro-doppler shift data, and draw a target surface micro-doppler shift image by using the processed data, so as to realize visual display of target three-dimensional micro-doppler information and expand the application of target micro-doppler information in the fields of target identification and motion characteristic research.
In order to achieve the above purpose, the technical solution of the embodiment of the present application is as follows:
an exemplary embodiment comprises a turntable, a cone object, a laser, a scanning galvanometer, a fiber beam splitter, a fiber beam combiner, an acousto-optic modulator, a polarization controller, a circulator, a photoelectric detector, a data acquisition card and a data processing system; the laser outputs monochromatic laser, the monochromatic laser is split by the optical fiber beam splitter, one laser beam passes through the acousto-optic modulator, the polarization controller is used as a reference beam, the other laser beam passes through the circulator, the vibrating mirror irradiates on the surface of a moving cone target, micro Doppler information carrying the target returns to the circulator, the two laser beams are coherent at the optical fiber beam combiner and then irradiate on the photoelectric detector, the photoelectric detector converts optical signals into electric signals, the electric signals are input into the data acquisition card for analog-to-digital conversion and then FFT conversion, micro Doppler frequency shift data of a single point of the target are acquired and stored, micro Doppler frequency shift data of key positions of the contour and the surface structure are acquired, and the stored data are input into the data processing system for imaging display.
The data content input into the processing system comprises micro Doppler frequency shift data and target position information corresponding to the data, a triangular surface element subdivision strategy is set independently by the data processing system according to the position information, then three interpolation operations are carried out in the triangular surface element by combining the micro Doppler frequency shift data, the processed data is displayed in a thermodynamic diagram mode, namely the size of the micro Doppler frequency shift data can be represented on a two-dimensional image of the target surface in terms of color depth, and accordingly basis is provided for researchers to analyze micro Doppler characteristics of the whole target surface.
In some embodiments, the turntable may be replaced with a vibrating table, changing the jog form of the target from rotation to vibration.
In some embodiments, the motion pose of the cone object may be changed to obtain surface images of different angles of the object.
In some embodiments, the cone object may be replaced with another irregularly shaped model to capture an image of the irregular surface of the object.
In some embodiments, target surface micro-doppler shift imaging may be performed by inputting only target surface location and corresponding micro-doppler shift information into the data processing system.
In some embodiments, a default triangulation scheme, delaunay triangulation, is employed.
In some embodiments, a linear interpolation approach may be selected.
In some embodiments, real-time processing and display of images may be achieved using high-performance data processing devices.
In some embodiments, the data acquisition card may be replaced with a data acquisition device that may perform FFT conversion.
In some embodiments, the data processing system may be integrated with the data acquisition end to enable automated data processing and image display.
The beneficial effects are that:
the method adopts a triangle surface element subdivision and interpolation method to process the discretized micro Doppler frequency shift data, and utilizes the processed data and the position information of the target surface to realize the target surface micro Doppler frequency shift imaging system. The integral distribution characteristics of micro Doppler frequency shift on the surface of the target can be obtained by the frequency shift image, and the geometrical characteristics of the target are combined with the micro Doppler information of the target, so that the research on the integral micro motion characteristics of the target is realized, and the research on the micro motion of the target is expanded.
Drawings
Fig. 1 depicts the basic structure of the target micro doppler shift imaging system of the present application.
Fig. 2 depicts a schematic view of the rotation of a cone object with different postures, the dotted line is the rotation axis of the cone object, and the arrow indicates the irradiation direction of laser light, (a) a schematic view of an upright cone object, (b) a schematic view of a depression cone object.
Fig. 3 depicts a block flow diagram of the process of the present application for processing and imaging micro-doppler shift data.
Fig. 4 depicts a plot of the results of micro-doppler shift imaging of different pose cone target rotations, (a) upright cone target micro-doppler shift imaging plot (b) prone cone target micro-doppler shift imaging plot.
Fig. 5 depicts an irregularity model schematic.
Fig. 6 depicts a graph of micro doppler shift imaging results for irregular model target vibrations.
Detailed Description
The present application will now be described in detail with reference to the examples shown in fig. 1 and 3.
The target micro Doppler frequency shift imaging system comprises a laser 1, an optical fiber beam splitter 2, an acousto-optic modulator 3, a polarization controller 4, an optical fiber beam combiner 5, a photoelectric detector 6, a data acquisition card 7, a data processing system 8, a circulator 12 and a scanning galvanometer 11.
It should be noted that, the structure and concept of the target micro doppler shift imaging system, rather than the structure of the device, include the upright cone target 10 (as shown in fig. 2 (a)), and the turntable 9.
The specific workflow of this embodiment is as follows:
the laser 1 emits monochromatic laser light as signal light;
the optical fiber beam splitter 2 divides a beam of laser into two beams, one beam is used as a reference beam, and the other beam is used as a detection beam;
the acousto-optic modulator 3 modulates the reference beam and adds a center frequency shift with the frequency of 100MHz to the reference beam;
the polarization controller 4 controls the polarization state of the reference laser light;
the circulator 12 outputs a detection light beam, the detection light beam scans and detects micro Doppler information of micro motion on the surface of a cone target 10 spinning on the turntable 9 through the scanning galvanometer 11, and the circulator receives a reflected light beam;
the laser beam combiner 5 carries out coherence between the reference beam and the detection beam returned by the circulator and outputs a coherent beam to the photoelectric detector 6;
the photoelectric detector 6 converts the received coherent optical signals into electric signals and transmits the electric signals to the data acquisition card 7;
the data acquisition card 7 performs FFT conversion, saves micro Doppler frequency shift data of the target point and transmits the micro Doppler frequency shift data to the data processing system;
the data processing system 8 receives the micro Doppler shift data of the target surface and calibrates the position information of each data acquisition point, and selects a proper triangular surface element subdivision strategy according to the position information of the data acquisition points. For this embodiment, triangular vertices of a triangular binning are selected autonomously to form a set of binned bins against which the binning of the target surface is performed. The program is split, the system returns the face metadata, the face metadata is combined with the micro Doppler frequency shift data of the vertex, the cubic interpolation operation is selected, and the system returns an interpolator based on the face metadata and the corresponding micro Doppler frequency shift. And the interpolator carries out interpolation operation on other position points which are not detected in the surface bin of the target, and returns interpolation results of micro Doppler frequency shift data of the corresponding position. And drawing the target surface position information and the corresponding micro Doppler shift data in a thermodynamic diagram form, and completing the imaging task of the target surface micro Doppler shift.
In this embodiment, triangle vertices of the binning subdivision are selected autonomously, to ensure that all data acquisition points are contained, that no gaps exist for subdivision of the target surface, and that the subdivision triangles are contiguous and non-overlapping, with common edges but no area overlap.
In this example, we use a triangle mesh-based cubic interpolation method, in the calculation process, firstly, triangle surface element subdivision is performed, and three vertexes (x 1 ,y 1 ),(x 2 ,y 2 ),(x 3 ,y 3 ) The values of the basis vectors in the barycentric coordinate system are calculated, and then the function values and derivative values of the interpolation points are calculated according to the values of the basis vectors. The specific calculation process is as follows:
1. calculating the area A of triangle and the value B of base vector in gravity center coordinate system i (x, y), wherein i=1, 2,3:
2. calculating the function value f (x, y) and derivative value f of the interpolation point from the value of the basis vector x (x,y)、f y (x,y)：
Wherein z is i The function value at the vertex of the triangle is used for returning the function value and the derivative value of the interpolation point as the result, so as to realize smooth interpolation.
3. Derivative information inside the triangle bin can be used to solve for the gradient value (g 1 ,g 2 ) The contour direction at the interpolation point can be calculated by the gradient value.
After interpolation operation of the discretized micro Doppler frequency shift data is completed, drawing a frequency shift image according to the function value of the interpolation point and the position of the contour line. Specifically, the thermodynamic diagram of the target micro Doppler frequency shift data is drawn by inputting the interpolation function value and the position of the contour line into the drawing function, the characteristic of the overall micro Doppler frequency shift of the target surface is intuitively displayed, and the imaging result is shown in fig. 4 (a).
In some embodiments, turret 9 is replaced with a vibrating table, the micro-doppler effect of the dither target is detected, and its micro-doppler shift is used for imaging.
In some embodiments, the motion posture of the cone object 9 can be changed, the upright type is the nodding type, the rotation posture of the cone object is changed from fig. 2 (a) to fig. 2 (b), and the imaging result is shown in fig. 4 (b).
In some embodiments, the cone object 9 may be replaced with an irregular model as shown in fig. 5, the turntable 10 may be replaced with a vibrating table, and the micro doppler characteristics of the irregular object model may be detected, and the imaging result is shown in fig. 6.
In some embodiments, a detection system formed by the laser 1, the optical fiber beam splitter 2, the acousto-optic modulator 3, the polarization controller 4, the laser beam combiner 5, the photoelectric detector 6, the data acquisition card 7, the circulator 12 and the scanning galvanometer 11 can be used with the data processing system 8 respectively, and the data processing system 8 can be used for calibrating the target surface position by using the saved micro Doppler frequency shift data or can be used for simulation imaging by using the data processing system only according to a target detection model as a preview of research.
In some embodiments, a default triangulation scheme, delaunay triangulation, may be used according to the data processing and imaging flow diagram of FIG. 3. The specific implementation mode is as follows:
1. suppose that a set of coordinates (x i ,y i ) A super triangle is first constructed so that all points are inside the boundaries of this triangle.
2. Each point is added to the triangulation one by one in order. One point p at a time i Calculating p i Relationship to the circumscribed circles (also called circumscribed spheres) of all triangles in the triangulation: if the triangle is positioned inside the circumscribed circle of a certain triangle, the triangle is deleted from the subdivision, and p is simultaneously removed i Is connected with three vertexes of the triangle to form three new triangles. If p is i Not inside the circumscribed circle of any triangle, the point is skipped.
3. When all points are added to the subdivision, all triangles associated with the supertriangle need to be deleted to obtain the final subdivision result.
The final result of Delaunay triangulation meets the following properties:
1. any two triangle circumscribed circles do not contain other points inside.
2. Any two adjacent triangles share a common boundary.
In some embodiments, the interpolation mode used can be replaced after the surface element is split, and the linear interpolator is used instead of the cubic interpolator to interpolate the discretized data.
In some embodiments, the program of the data processing system can be integrated into the system on chip, the collected data is directly input into the system on chip for processing, an upper computer display UI interface is designed on the integrated system, an upper computer operating system and a more visual display interface which are more convenient to operate are developed, meanwhile, the data storage and the data transmission flow of the data acquisition card 7 are omitted, and the real-time data processing and the instant image display are facilitated.
In some embodiments, the data acquisition card 7 can be replaced by a data acquisition device capable of performing FFT conversion, such as a high-speed FPGA system capable of performing FFT conversion and AD acquisition, and the processed data is directly sent to an upper computer for processing and displaying, so that the processing efficiency is improved, and the instantaneity is enhanced.
In some embodiments, a detection system formed by the laser 1, the optical fiber beam splitter 2, the acousto-optic modulator 3, the polarization controller 4, the laser beam combiner 5, the photoelectric detector 6, the data acquisition card 7, the circulator 12 and the scanning galvanometer 11 can be integrated with the data processing system 8, so that a miniaturized portable device is designed, various types of detection targets can be imaged in a handheld or airborne mode, and a reference is provided for analyzing the integral micro Doppler characteristics of the target surface.
In summary, the above embodiments are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. The target micro Doppler frequency shift imaging system is characterized by comprising a laser, an optical fiber beam splitter, an acousto-optic modulator, a polarization controller, a laser beam combiner, a photoelectric detector, a data acquisition card, a data processing system, a circulator and a scanning galvanometer; the laser provides monochromatic laser; the optical fiber beam splitter is used for realizing light splitting and providing a detection beam and a reference beam; the acousto-optic modulator is used for adding 100MHz center frequency shift to the reference beam; the polarization controller is used for controlling the polarization state of the reference beam; the circulator is used for outputting and receiving a detection beam and a return beam carrying micro Doppler information, and is coherent with a reference beam at the optical fiber combiner; the photoelectric detector converts the coherent optical signal into an electric signal and inputs the electric signal into the data acquisition card; the data acquisition card performs FFT conversion on an input signal and stores micro Doppler frequency shift data of an acquisition point; the data processing system adds position information to the micro Doppler frequency shift data of the acquisition point, performs triangular surface element subdivision according to the position information, performs cubic interpolation operation on the subdivided surface element, and combines an operation result with the position information to draw a target micro Doppler frequency shift thermodynamic diagram.
2. The micro-doppler shift imaging system of claim 1, wherein the detection target can be in the form of rotation or vibration.
3. The micro-doppler shift imaging system of claim 1, wherein micro-doppler shifts of different angular micro-movements of the target can be imaged.
4. The target micro-doppler shift imaging system of claim 1, wherein micro-doppler shift imaging can be performed on different shaped target models.
5. The micro-doppler shift imaging system of claim 1, wherein the simulated micro-doppler shift data can be directly input into the data processing system without acquisition by the detection system.
6. The target micro-doppler shift imaging system of claim 1, wherein the data processing system is capable of implementing an autonomously set binning strategy or default Delaunay triangulation.
7. The target micro-doppler shift imaging system of claim 1, wherein interpolation mode can be modified to replace cubic interpolation operation to linear interpolation operation.
8. The target micro-Doppler frequency shift imaging system of claim 1, wherein the data acquisition card and the data processing system can be integrated into a system on a chip to perform FFT operation, binning and interpolation operation, and realize thermodynamic diagram drawing and image display so as to enhance the real-time performance and accuracy of the system.
9. The micro-doppler shift imaging system of claim 1, wherein the coherent detection device and data processing system can be designed for small and portable use on-board or on-board.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311799477.6A CN117872394A (en) | 2023-12-26 | 2023-12-26 | Target micro Doppler frequency shift imaging system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311799477.6A CN117872394A (en) | 2023-12-26 | 2023-12-26 | Target micro Doppler frequency shift imaging system |
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| CN202311799477.6A Pending CN117872394A (en) | 2023-12-26 | 2023-12-26 | Target micro Doppler frequency shift imaging system |
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