High-integration millimeter wave radio frequency optical common-caliber composite imaging detector with tightly constrained space structure

Abstract

The invention discloses a high-integration millimeter wave radio frequency optical common-caliber composite imaging detector with a tightly constrained space structure. The high-integration millimeter wave radio frequency optical common-caliber composite imaging detector comprises an optical camera, an antenna radio frequency integrated board, an image processing board card, a radar processing board card and an interface power supply board, the optical camera is electrically connected with the image processing board card, and image signals collected by the optical camera are processed through the image processing board card; the antenna radio frequency integrated board adopts a structure that a multiple-input multiple-output TI AWR243 chip is back-pasted on a multilayer microwave composite board integrating the functions of an antenna unit, a feed network and a power division network, and is connected with a radar processing board card through an FPC (Flexible Printed Circuit) interface, and a power supply is directly connected with an interface power supply board through a bonding wire. According to the invention, a millimeter wave array radar sensor and an optical sensor are combined, a mature and miniaturized millimeter wave chip and an optical camera are utilized, and a radio frequency optical composite detector which is simple in structure, compact in structure and small in size is designed on the premise that the size, the load and the like of a carrier platform are limited.

Description

Technical Field

[0001] The present invention relates to the technical field of radar-optical composite detection, and in particular to a highly integrated millimeter-wave radio-frequency optical common-aperture composite imaging detector with a tightly constrained spatial structure. Background Art

[0002] In today's increasingly complex electromagnetic environment in distributed unmanned combat scenarios, the demand for environmental perception and target detection and recognition of lightweight and small unmanned platforms has increased significantly. The optical detectors used in traditional lightweight and small unmanned platforms have high costs, and both the detection range and application scenarios are limited. Patent document CN 118746828 A (application number: 202411070103.5) discloses a chip-integrated millimeter-wave optical common-aperture detection system, which adopts an optoelectronic hybrid design, integrates a millimeter-wave array and an optical imaging system, has a high integration level, is lightweight, and can be widely applied to small platforms such as low-earth orbit satellites and unmanned aerial vehicles. However, its structure is relatively complex, the cost is high, and the reliability is not high.

[0003] Aiming at the problems of high cost, limited detection range and application scenarios of the detection module in existing lightweight and small unmanned platforms, the radio-frequency optical common-aperture composite imaging detector under the constraints of limited volume, payload and cost is studied emphatically to provide key technical support for the development of low-cost unmanned aerial vehicle cluster detection and attack tactics. It can improve the precision strike capabilities of cruise missiles, unmanned aerial vehicles, precision-guided munitions, etc., and lay a foundation for realizing distributed cooperative detection and cluster combat of unmanned aerial vehicle swarms, etc.

[0004] The problems existing in the prior art mainly include: 1. On lightweight and small unmanned platforms that can be carried, the volume, power consumption level and development cost of the detector are all restricted by various constraints, and it is difficult to design the structural shape of the detector; in addition, during the process of detecting the ground, due to factors such as the distance between the detector and the target, the movement speed of the platform itself, ground targets and ground clutter background, many parameters of the millimeter-wave array radar restrict each other, and the parameter matching between the radio-frequency and optical sensors makes it difficult to optimize the design of the system parameters of the detector. Therefore, how to complete the overall design of the detector under various complex constraints and try to achieve higher detection performance is a key problem to be faced.

[0005] 2. The traditional co-planar integration method of the MIMO array chip and the radiation surface cannot be used for the radio frequency optical composite detector; the traditional LTCC + micro-assembly board and production process are no longer applicable. In addition, the co-aperture optical module occupies part of the depth space of the array radar system, greatly increasing the difficulty of meeting the requirements of high density, equal feed length, and low loss during the integration of the millimeter wave array radar. Therefore, the optimal selection of the integration scheme, the optimization of design parameters, and the high tolerance design based on the processing tolerance of the high-density multi-layer millimeter wave composite board are the key technologies to achieve the performance of the high-density integrated array radar under the co-aperture condition of this project.

[0006] 3. For the composite imaging detector on a lightweight and small unmanned aerial platform, the imaging error problem caused by the stability of the platform's own motion attitude needs to be solved first. On the basis of error compensation, the millimeter wave array radar and the optical camera can respectively obtain scene images with different characteristics, and the radar image and the optical image can be converted into prior information to realize the fusion imaging of the two. Finally, combining the two images can provide a more abundant composite imaging result for environmental perception and target detection. However, how to establish the correlation information between the imaging models of the millimeter wave radar and the optical sensor, achieve the matching in time and space, and select different imaging modes according to different application scenarios and application requirements is a key problem in realizing the composite imaging detector.

[0007] The information disclosed in this background art section is only intended to deepen the understanding of the overall background art of the present invention, and should not be regarded as an admission or any form of implication that this information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of the present invention is to provide a high-integration millimeter wave radio frequency optical co-aperture composite imaging detector with a tightly constrained spatial structure to solve the problems existing in the prior art.

[0009] To achieve the above purpose, the present invention adopts the following technical solutions: The present invention provides a high-integration millimeter wave radio frequency optical co-aperture composite imaging detector with a tightly constrained spatial structure, including an optical camera, an antenna radio frequency integrated board, an image processing board card, a radar processing board card, and an interface power supply board; wherein, The optical camera is electrically connected to the image processing board card, and the image signal collected by the optical camera is processed by the image processing board card; The antenna radio frequency integrated board adopts a structure in which the multi-transmit and multi-receive TI AWR2243 chips are back-mounted on a multi-layer microwave composite board integrated with the functions of antenna units, feed networks, and power distribution networks, and is connected to the radar processing board card through an FPC interface; the power supply of the antenna radio frequency integrated board is directly connected to the interface power supply board through wire bonding.

[0010] Furthermore, the receiving antennas in the integrated antenna and RF board are divided into two rows, with 16 in each row, for a total of 32 receiving antennas; there are two columns on each side, a total of four columns, which are transmitting antennas, with 6 in each row, for a total of 24 transmitting antennas; the middle circular opening is the space occupied by the optical camera; the integrated antenna and RF board uses 8 TI AWR2243 chips, supporting 32-channel reception and 24-channel transmission; they are respectively connected one-to-one with 32 receiving antenna units and 24 transmitting units; the virtual array imaging technology is adopted to construct a virtual array with a scale of 32*24; The receiving antennas use a 1x4 series-fed array, and the Taylor synthesis method is used to weight each element to reduce the sidelobe; the transmitting antennas use a single patch, which has a relatively wide beam width in both the azimuth and elevation planes; The feeding method of the integrated antenna and RF board is a back-feed through-layer design; the patch antenna on the top layer of the RF board is connected to the TI AWR2243 chip back-mounted on the bottom layer through a vertical via interconnection structure. The RF signal is transmitted from the microstrip line at the bottom of the RF board to the top layer through the vertical via interconnection structure, and then fed into the patch antenna through the microstrip line. At the same time, the lengths of 24 transmitting channels are controlled to be equal on the microstrip path to ensure equal-phase excitation of each antenna; the vertical via interconnection structure is a group of metallized vias. The main signal vias transmit signals, and the vias surrounding them form a ground. The whole can be compared to a coaxial-like structure to ensure signal transmission.

[0011] Furthermore, the optical camera is embedded in the center of the millimeter-wave antenna aperture. The optical camera uses a CCD camera, and the CCD camera includes an optical lens, an electronic diaphragm, and a visible light detector; the electronic diaphragm controls the size of the aperture diaphragm to achieve clear imaging under different object radiation brightness conditions.

[0012] Furthermore, the composite imaging detector is mounted on the strapdown platform. On the basis of error compensation, the millimeter-wave array radar is used to obtain two-dimensional or three-dimensional imaging results of the target, while the optical camera is used to obtain high-resolution images of the target, so that the composite detector obtains two detection images in advance; according to different application scenarios and application requirements, the radar image and the optical image are mutual prior information. On the one hand, the radar obtains the azimuth angle and distance information of the target and guides the optical camera to image a specified area. On the other hand, the optical image guides the radar to perform high-precision measurement on a specified target area to achieve the fusion imaging of the two being mutual priors; finally, by comprehensively using the high-resolution features of the contour and details in the optical image and the information of strong scattering points, distance, and height in the radar image, the two images are combined to enhance the environmental and target features, providing a more abundant composite imaging result for environmental perception and target detection.

[0013] Adopting the above technical solutions, the present invention has the following beneficial effects: The present invention combines a millimeter-wave array radar sensor and an optical sensor, and uses a mature and miniaturized millimeter-wave chip and an optical camera to design and implement a radio-frequency optical composite detector with a simple structure, a compact structure, and a small volume on the premise that the volume and load of the carrier platform are limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0015] Figure 1 It is the antenna array layout design diagram provided in the first embodiment of the present invention; Figure 2 It is the structure diagram of the radio-frequency optical composite detector provided in the first embodiment of the present invention; Figure 3 It is the block diagram of the radio-frequency optical composite detector equipment system provided in the first embodiment of the present invention; Figure 4 It is the top view, side view, and rear view of the radio-frequency part provided in the first embodiment of the present invention; Figure 5 It is the optical path schematic diagram of the optical camera provided in the first embodiment of the present invention; Figure 6 It is the multi-mode composite imaging block diagram provided in the first embodiment of the present invention; Figure 7 It is the top view, side view, and rear view of the radio-frequency part provided in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the drawings. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0017] The following will detail the specific embodiments of the present invention in conjunction with the drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not used to limit the present invention. Embodiment 1

[0018] Combined with Figures 1-6As shown in the figure, the present invention provides a highly integrated millimeter-wave radio frequency optical co-aperture composite imaging detector with a tightly constrained spatial structure. The composite detector includes an optical camera, an antenna-radio frequency integrated board, an image processing board, a radar processing board, and an interface power supply board. In terms of hardware, the low-cost array radar radio frequency front-end is realized by using high-density, high-efficiency, and miniaturized integrated chips, and the signal processing is realized by using a ZYNQ processor with an SOC architecture. To reduce the development cost of the radio frequency front-end module and improve the system integration, the multi-transmit and multi-receive TI AWR2243 chips are back-mounted on a multi-layer microwave composite board integrated with functions such as antenna elements, feeding networks, and power distribution networks, and are connected to the radar processing board through an FPC interface. The power supply is directly connected to the power interface board through wire bonding. The image processing board is connected to the camera to process the image signal.

[0019] The millimeter-wave antenna array of this application operates at 76 - 81 GHz, with a center frequency of 80 GHz, and its corresponding wavelength is 3.75 mm. The layout design of the antenna array is as Figure 1 shown in the figure. The upper and lower rows in the figure are receiving antennas, with 16 in a single row and a total of 32 receiving antennas; there are four columns on the left and right, a total of four columns of transmitting antennas, with 6 in a single row and a total of 24 transmitting antennas; the circular opening in the middle is the space occupied by the optical lens. Eight TI AWR2243 chips are used, supporting 32-channel reception and 24-channel transmission; they are respectively connected to 32 receiving antenna elements and 24 transmitting elements one by one. The virtual array imaging technology is adopted to construct a virtual array with a scale of 32 * 24.

[0020] Since the spacing of the receiving antennas in the horizontal direction is limited to one wavelength, a 1x4 series-fed array is used, and the Taylor synthesis method is used to weight each element to reduce the side lobes; the transmitting antennas use single patches (omnidirectional antennas), which have relatively wide beam widths in both the azimuth and elevation planes.

[0021] Due to the compact space of the overall module, the feeding method is a back-feeding through-layer design. The patch antenna on the top layer of the radio frequency board is connected to the TI AWR2243 chip back-mounted on the bottom layer through a vertical via interconnection structure. The radio frequency signal is transmitted from the microstrip line at the bottom of the radio frequency board to the top layer through the vertical via interconnection structure, and then fed into the patch antenna through the microstrip line. At the same time, the lengths of 24 transmitting channels are controlled to be equal on the microstrip path to ensure equal-phase excitation of each antenna. The vertical via interconnection structure is a group of metallized vias. The main signal vias transmit signals, and the surrounding vias form a ground. The whole can be compared to a coaxial-like structure to ensure signal transmission.

[0022] In this embodiment, the optical lens is embedded in the center of the millimeter-wave antenna aperture. An optical system with high dynamic range and large field of view is selected. Under a lens of no more than 35 mm, imaging of the entire target is achieved. A type of optical lens that meets the requirements of this project is a CCD camera, and its optical path schematic diagram and appearance are respectively as Figure 5and Figure 6 As shown, it mainly consists of an optical lens, an electronic diaphragm, and a visible light detector. The electronic diaphragm controls the size of the aperture diaphragm to achieve clear imaging under different object radiation brightness conditions. The use of a symmetric system structure helps to obtain an image with a large field of view, low distortion, and good image quality. At the back end, automatic focusing of the lens can be achieved through program control, which has the advantages of small size, affordable price, low power consumption, and fast zoom speed.

[0023] The composite imaging detector of this application is loaded on the strapdown platform. In environmental perception and target detection and recognition, it is necessary to first decouple the carrier motion and the target motion, as well as the influence of errors such as the carrier's own jitter. On the basis of error compensation, the millimeter-wave array radar can obtain two-dimensional or three-dimensional imaging results of the target, and the optical camera can also obtain a high-resolution image of the target, so that the composite detector can obtain two detection images in advance; and according to different application scenarios and application requirements, the radar image and the optical image can be used as prior information for each other. On the one hand, the radar can obtain the azimuth angle and distance information of the target and guide the optical camera to image a specified area. On the other hand, the optical image can also guide the radar to perform high-precision measurement on a specified target area to achieve fusion imaging with each other as prior information; finally, by comprehensively using the high-resolution features such as contours and details in the optical image and the information such as strong scattering points, distance, and height in the radar image, the two images are combined to enhance the environmental and target features, which can provide a more abundant composite imaging result for environmental perception and target detection. Embodiment 2

[0024] Combined with Figure 7 As shown, considering the radiation of the feeder on the RF board and the electromagnetic leakage and coupling caused by the manufacturing process error, an extended design is required. The main points of the process's influence on performance include: 1) The parasitic effect of the processing diameter of the vertical through-hole feeding structure in the 3-mm frequency band cannot be ignored; 2) The electric field distribution near the vertical through-hole is dense, and the manufacturing tolerance will have a great impact on the performance and consistency of the 3-mm array antenna. Considering the above factors, a slot-coupled feeding form that is not sensitive to processing errors is selected. Constructing a substrate integrated waveguide (SIW) structure in a multi-layer microwave composite substrate can reduce the influence of processing errors to an acceptable level. The SIW and the chip pins are also interconnected using the coaxial-like vertical transition structure in the main embodiment to effectively control electromagnetic leakage radiation on the premise of ensuring transmission impedance matching.

[0025] In terms of process implementation, the unit still uses a microstrip patch antenna. The top layer of the multi-layer composite board is the antenna patch, and the bottom layer is the microstrip feeder. The feeder and the patch are vertically interconnected through a via structure, which includes a slot-coupled feeding structure, a SIW isolation transmission waveguide, and a coaxial-like vertical transition structure. The signal is transmitted from the microstrip line at the bottom of the RF board, enters the SIW cavity through the vertical interconnection structure of the via, and then radiates externally through the coupling slot to the patch antenna.

[0026] Compared with the prior art, the innovations of this application mainly include: 1. The overall technology of the co-aperture composite imaging detector under multiple constraints: Under the constraints of the limited volume, power consumption, and cost of the lightweight unmanned platform, study and design the overall architecture of the co-aperture composite imaging detector with a RF array and an optical camera. Select low-cost millimeter-wave chips and optical camera modules that meet the performance index requirements, optimize the layout of the RF array radar, and seek the optimization of the performance of the composite imaging detector on the premise that parameters such as signal-to-noise ratio, detection range and accuracy, and imaging resolution are mutually restricted.

[0027] 2. The motion-adaptive RF-optical multi-mode cognitive imaging technology: According to the motion characteristics of the detector's carrier platform and the requirements of target imaging performance, combine the different target information and features collected by the RF sensor and the optical sensor, study the independent imaging methods of the RF radar and the optical camera, the fusion imaging method with each other as a priori, and the composite enhancement imaging method respectively, and analyze the characteristics and applicability of different imaging modes to achieve the multi-mode cognitive imaging of the composite detector.

[0028] 3. The millimeter-wave high-density integration technology: According to the overall architecture design of the composite imaging detector, study the high-density integration technology in the millimeter-wave band within a limited and irregular space, realize the composite structure of the millimeter-wave array radar and the optical camera with a common aperture, and reduce the space size and cost of the system.

[0029] Compared with the prior art, the beneficial technical effects of this application mainly include: 1. The present invention combines the millimeter-wave array radar sensor and the optical sensor, and uses mature and miniaturized millimeter-wave chips and optical cameras to design and implement a simple-structured, compact, and small-sized RF-optical composite detector on the premise of limited volume, load, etc. of the carrier platform.

[0030] 2. Cost control. Commercially available mature mass-produced chips are used in hardware implementation; in terms of backend processing, through the fusion processing of the millimeter-wave sensor and the optical sensor in the imaging process, the data volume and calculation volume are reduced in advance, and a low-cost processor can meet the data processing requirements.

[0031] 3. High-density integration technology of millimeter-wave array radar in confined spaces. The spacing between millimeter-wave array antenna elements is small and the processing difficulty is high. Therefore, patch antennas with edge feeding or embedded feeding are mostly used, which simplifies the process, but has a narrow bandwidth and the feeding lines inevitably participate in radiation, resulting in the performance of the array antenna being difficult to reach the optimal. In addition, the optical camera further occupies the limited space resources. Based on high-density microwave boards, this project integrates the feeding network and power supply control lines of the millimeter-wave array antenna on the inner layer of the microwave board, and uses ground-plane slot coupling feeding, which has a wide bandwidth and eliminates the radiation of the feeding lines. Through reasonable stack-up planning and tolerance design, the process and microwave performance are taken into account.

[0032] 4. Fusion imaging method based on millimeter-wave and optical complementary priors. This application breaks through the traditional information fusion method and completes the information fusion between different sensors during the imaging process before pixel-level fusion. The radar image and optical image can be converted into prior information. On the one hand, the azimuth or elevation angle of the target is obtained through optical preprocessing and provided to the array radar, enabling the radar to make further high-precision measurements within a limited angle range. On the other hand, when the detector passes through environments such as clouds and smoke where the optical sensor cannot work effectively, and the radar information is still valid, the optical image of the previous section can be selected for display.

[0033] 5. The RF part of this prototype uses the MIMO system, and 32 receive and 24 transmit independent antennas and RF channels are integrated in one body within an aperture of 70×75 mm2 with a central opening diameter of 36 mm. It can meet the detection accuracy with a field of view ≥ ±45° and an angular resolution of 2.5°. The optical part meets the field of view ≥ ±10° and a resolution of 1920×1080 pixels, and the comprehensive performance is relatively good compared with similar products.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A highly integrated millimeter-wave radio-frequency optical co-aperture compound imaging detector with a tightly constrained spatial structure, characterized in that, It includes an optical camera, an antenna-radio frequency integrated board, an image processing board, a radar processing board, and an interface power board; among which, the optical camera is electrically connected to the image processing board, and the image signal collected by the optical camera is processed through the image processing board; the antenna-radio frequency integrated board adopts a structure in which the multi-transmit and multi-receive TI AWR2243 chip is back-mounted on a multi-layer microwave composite board integrated with the functions of antenna unit, feeding network, and power distribution network, and is connected to the radar processing board through an FPC interface; the power supply of the antenna-radio frequency integrated board is directly connected to the interface power board through wire bonding.

2. The high-integration millimeter-wave radio frequency optical common-aperture compound imaging detector with tightly constrained spatial structure according to claim 1, wherein In the antenna-radio frequency integrated board, the receiving antennas are divided into two rows, with 16 in a single row, totaling 32 receiving antennas; there are two columns on the left and right, a total of four columns are transmitting antennas, with 6 in a single row, totaling 24 transmitting antennas; the middle circular opening is the space occupied by the optical camera; the antenna-radio frequency integrated board uses 8 TI AWR2243 chips, supports 32-channel reception and 24-channel transmission; they are respectively docked with 32 receiving antenna units and 24 transmitting units one by one; the virtual array imaging technology is adopted to construct a virtual array with a scale of 32*24; the receiving antenna uses a 1x4 series-fed array, and at the same time, the Taylor synthesis method is used to weight each element to reduce the side lobe; the transmitting antenna uses a single patch, and has a relatively wide beam width in both the azimuth and elevation planes; the feeding method of the antenna-radio frequency integrated board is a back-feed through-layer design; the patch antenna on the top layer of the radio frequency board is connected to the TI AWR2243 chip back-mounted on the bottom layer through a vertical via interconnection structure, and the radio frequency signal is transmitted from the microstrip line at the bottom of the radio frequency board to the top layer through the vertical via interconnection structure, and then fed into the patch antenna through the microstrip line. At the same time, the lengths of 24 transmitting channels are controlled to be equal on the microstrip path to ensure equal-phase excitation of each antenna; the vertical via interconnection structure is a group of metallized vias, the main signal holes transmit signals, and the surrounding vias form a ground, and the whole can be compared to a coaxial-like structure to ensure signal transmission.

3. The high-integration millimeter-wave radio frequency optical common-aperture compound imaging detector with tightly constrained spatial structure according to claim 1, wherein the optical camera is embedded in the center of the millimeter-wave antenna aperture. The optical camera uses a CCD camera, and the CCD camera includes an optical lens, an electronic shutter, and a visible light detector; the electronic shutter controls the size of the aperture diaphragm to achieve clear imaging under different object radiation brightness conditions.

4. The high-integration millimeter-wave radio frequency optical co-aperture compound imaging detector with a tightly constrained spatial structure according to claim 1, wherein The composite imaging detector is mounted on a strapdown platform. On the basis of error compensation, the millimeter-wave array radar is used to obtain two-dimensional or three-dimensional imaging results of the target, while the optical camera is used to obtain high-resolution images of the target, so that the composite detector obtains two detection images in advance. According to different application scenarios and application requirements, the radar image and the optical image are mutual prior information. On the one hand, the radar obtains the azimuth angle and distance information of the target and guides the optical camera to image a specified area. On the other hand, the optical image guides the radar to perform high-precision measurement on a specified target area, realizing the fusion imaging with each other as prior information. Finally, by comprehensively using the high-resolution features of the contour and details in the optical image and the information of strong scattering points, distance and height in the radar image, the two images are combined to enhance the environmental and target features, providing a more abundant composite imaging result for environmental perception and target detection.

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