CN210534345U

CN210534345U - Security check equipment

Info

Publication number: CN210534345U
Application number: CN201822275885.2U
Authority: CN
Inventors: 赵自然; 游�燕; 李元景; 马旭明; 武剑
Original assignee: Tsinghua University; Nuctech Co Ltd
Current assignee: Tsinghua University; Nuctech Co Ltd
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2020-05-15
Anticipated expiration: 2028-12-29

Abstract

A security device comprising a body to be secured in a field and an electromagnetic imaging apparatus mounted on the body, the electromagnetic imaging apparatus comprising: a two-dimensional multiple-transmit multiple-receive transmit-receive array panel, the two-dimensional multiple-transmit multiple-receive transmit-receive array panel comprising: at least one two-dimensional multiple-transmit-multiple-receive sub-array, each two-dimensional multiple-transmit-multiple-receive sub-array comprising a plurality of transmit antennas and a plurality of receive antennas, the plurality of transmit antennas and the plurality of receive antennas being arranged such that equivalent phase centers are arranged in a two-dimensional array; and a control circuit; signal processing means for reconstructing an image of the object to be examined from the received echo signals; and the display device is used for displaying the reconstructed image of the detected object.

Description

Security check equipment

Technical Field

The disclosure relates to the technical field of safety detection, in particular to safety inspection equipment.

Background

At present, the anti-terrorism form at home and abroad is increasingly severe, and terrorists carry dangerous goods such as guns, cutters, explosives, drugs and the like with themselves in a hidden mode, so that public safety is greatly threatened. Cases such as violent attack or robbery occur in special occasions such as airports, railway stations, hotels, campuses, banks and the like. The security measures in these special locations have not been able to meet the ever increasing security requirements.

At present, the international public safety technology mainly comprises manual inspection, a handheld metal detector, a metal detector door, an X-ray machine, explosive measurement detection, a liquid detector and the like.

However, the manual detection has high accuracy but low efficiency, and the person to be detected is easy to generate a contradiction due to physical contact. The handheld metal detector and the metal detection door only can correspond to metal and cannot detect nonmetal dangerous goods. Both explosive weighing detection and liquid detection instruments have the defects of single function and limited application. The X-ray machine is not suitable for human body security inspection because of its ionizing property. The human body security check equipment mainly comprises an X-ray back scattering human body imaging device and a millimeter wave human body imaging device. The X-ray back scattering human body imaging device utilizes signals scattered by X-rays incident to the surface of a human body to carry out imaging. The passive terahertz human body security inspection system is low in image signal-to-noise ratio and poor in penetrability. The imaging rate of the active millimeter wave security inspection door based on the three-dimensional holographic technology is generally 2-3 s/person, real-time imaging cannot be realized, and the security inspection efficiency is low.

Therefore, the traditional security check equipment is not suitable for secret security check in public places.

Disclosure of Invention

According to an aspect of the present disclosure, there is provided a security inspection apparatus including a body fixed in a field and an electromagnetic imaging device mounted on the body, the electromagnetic imaging device including:

a two-dimensional multiple-transmit multiple-receive transmit-receive array panel, the two-dimensional multiple-transmit multiple-receive transmit-receive array panel comprising:

at least one two-dimensional multiple-transmit multiple-receive sub-array, each two-dimensional multiple-transmit multiple-receive sub-array including a plurality of transmitting antennas and a plurality of receiving antennas, a midpoint of a connecting line of each of the plurality of transmitting antennas and a corresponding one of the plurality of receiving antennas being one equivalent phase center, the plurality of transmitting antennas and the plurality of receiving antennas being arranged such that the equivalent phase centers are arranged in a two-dimensional array; and

the control circuit is used for controlling the plurality of transmitting antennas to transmit detection signals in the form of electromagnetic waves to the detected object according to a preset sequence and controlling the plurality of receiving antennas to receive echo signals from the object to be detected;

the signal processing device is connected with the two-dimensional multi-transmitting multi-receiving array panel and is used for reconstructing an image of the detected object according to the received echo signals;

and the display device is connected with the signal processing device and is used for displaying the reconstructed image of the detected object.

Preferably, the distance between adjacent transmitting antennas and/or adjacent receiving antennas in each two-dimensional multiple-transmission multiple-reception sub-array is an integral multiple of a wavelength corresponding to one of multiple frequencies of the detection signal, and the distance between adjacent equivalent phase centers is half of the wavelength of the detection signal.

Preferably, each two-dimensional multiple-transmit multiple-receive sub-array includes two rows of transmit antennas arranged along a first direction and two columns of receive antennas arranged along a second direction perpendicular to the first direction, the two rows of transmit antennas and the two columns of receive antennas forming a rectangular pattern.

Preferably, the two-dimensional multiple-transmit multiple-receive sub-array includes a row of transmitting antennas arranged along a first direction and a column of receiving antennas arranged along a second direction perpendicular to the first direction, the row and the column crossing to form a cross shape.

Preferably, the control circuit is configured to control the plurality of transmitting antennas in each two-dimensional multiple-transmitting and multiple-receiving sub-array to sequentially transmit the detection signal and control the plurality of receiving antennas in the two-dimensional multiple-transmitting and multiple-receiving sub-array to receive the echo signal; or the two-dimensional multi-transmission and multi-reception array panel is configured to control all transmitting antennas in the two-dimensional multi-transmission and multi-reception array panel to sequentially transmit detection signals and control all receiving antennas in the two-dimensional multi-transmission and multi-reception array panel to receive echo signals.

Preferably, the body has an integral structure, and the electromagnetic imaging apparatus is mounted on a side of the body facing the object to be inspected.

Preferably, the body includes a first portion and a second portion separated from each other, a space between the first portion and the second portion is used for passing the object to be inspected, and the electromagnetic imaging apparatus is mounted on a side of the first portion and/or the second portion facing the object to be inspected.

Preferably, the electromagnetic imaging apparatus further comprises: a distance measuring device mounted on the two-dimensional multi-transmitter multi-receiver array panel for measuring a distance between an object to be inspected and the two-dimensional multi-transmitter multi-receiver array panel;

the signal processing device is used for reconstructing an image of the detected object according to the distance between the detected object and the two-dimensional multi-transmitting and multi-receiving array panel and the received echo signals.

Preferably, the security inspection apparatus further comprises an alarm device connected to the signal processing device, and the processor is further configured to determine whether the object may contain a hazardous material based on a preset criterion according to the reconstructed image of the object, and if so, control the alarm device to alarm.

Preferably, the detection signal is a microwave millimeter wave with a frequency in the range of 10-300 GHz.

Preferably, the two-dimensional multiple-input multiple-output transceiving array panel has a length and a width both in the range of 10cm to-200 cm.

According to another aspect of the present disclosure, there is provided a control method of the security inspection apparatus, including:

controlling the two-dimensional multi-transmitting and multi-receiving array panel to transmit a detection signal to a detected object and receive an echo signal from the detected object; and

and reconstructing an image of the detected object according to the received echo signals.

Preferably, the reconstructing the image of the object to be examined comprises reconstructing the image of the object to be examined based on a holographic reconstruction algorithm or a back projection algorithm.

The electromagnetic imaging device in the security inspection equipment disclosed by the invention has the capabilities of quick scanning and quick image reconstruction, can be used for quickly performing security inspection on a moving human body or other objects, and does not need to make an object to be inspected still. According to this disclosed security installations's body is fixed in diversified complicated scene, can realize for the form of monomer or including a plurality of discrete parts, and it is better to hide the effect to the range of application is wider, can utilize dangerous goods such as gun, cutter and explosives, drugs that hidden mode was hand-carried to terrorist secretly to check, thereby improves the security of public occasion.

Drawings

FIG. 1 shows a schematic view of an electromagnetic imaging apparatus according to an embodiment of the present disclosure.

Fig. 2a shows a schematic structural diagram of a 2D MIMO antenna array according to an embodiment of the present disclosure.

Fig. 2b shows a schematic diagram of an equivalent phase center of the 2D MIMO antenna array of fig. 2 a.

Fig. 3 shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure.

Fig. 4 shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure.

Fig. 5 shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure.

Fig. 6 shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure.

Fig. 7a shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure.

Fig. 7b shows a schematic diagram of an equivalent phase center of the 2D MIMO antenna array of fig. 7 a.

Fig. 8a shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure.

Fig. 8b shows a schematic diagram of an equivalent phase center of the 2D MIMO antenna array of fig. 8 a.

Fig. 9 shows a schematic diagram of the working principle of a 2D MIMO antenna array according to an embodiment of the present disclosure.

Fig. 10 shows a schematic diagram of a security device according to an embodiment of the present disclosure.

Fig. 11 shows a schematic view of a security device according to another embodiment of the present disclosure.

Fig. 12 shows a schematic view of a security device according to another embodiment of the present disclosure.

Fig. 13 shows a schematic view of a security device according to another embodiment of the present disclosure.

Fig. 14 shows a schematic view of a security device according to another embodiment of the present disclosure.

Fig. 15 shows a schematic view of a security device according to another embodiment of the present disclosure.

Fig. 16 shows a schematic view of a security device according to another embodiment of the present disclosure.

Fig. 17 shows a schematic flowchart of a control method of a security inspection apparatus according to an embodiment of the present disclosure.

Detailed Description

While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the disclosure to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims. The figures are for illustration and are not drawn to scale.

The use of the terms "upper," "lower," "left," "right," and the like in this specification is not intended to limit the absolute orientation of the elements, but rather to describe relative positions of the elements in the figures to aid understanding; in this specification, "top side" and "bottom side" are orientations of upper and lower sides with respect to an object standing upright in general; "first," "second," and the like are also not intended to distinguish one element from another, but rather to distinguish one element from another.

Various embodiments according to the present disclosure are described below with reference to the drawings.

FIG. 1 illustrates an electromagnetic imaging apparatus according to one embodiment of the present disclosure. As shown in fig. 1, the electromagnetic imaging apparatus 10 includes a two-dimensional Multiple-Input Multiple-Output (2D MIMO) array panel 1, a signal processing apparatus 2, and a display apparatus 3.

The 2D MIMO array panel 1 may include a 2D MIMO antenna array 11 and a control circuit 12 (not shown in the figure). The 2D MIMO antenna array 11 includes at least one 2D MIMO sub-array, and the 2D MIMO sub-array includes a plurality of transmitting antennas and a plurality of receiving antennas, a midpoint of a line connecting each of the plurality of transmitting antennas and a corresponding one of the plurality of receiving antennas serves as an equivalent phase center (phase center), and the plurality of transmitting antennas and the plurality of receiving antennas are arranged such that the equivalent phase centers are arranged in a two-dimensional array. The control circuit 12 may control the plurality of transmitting antennas to transmit detection signals in the form of electromagnetic waves to the object to be inspected in a preset order, and control the plurality of receiving antennas to receive echo signals from the object to be inspected. In some embodiments, the 2D MIMO array panel 1 may be implemented by 76-81GHz chip, which has the advantages of high array integration level, low cost, and the like.

The signal processing device 2 may reconstruct an image of the object to be examined based on the echo signals received by the plurality of receiving antennas. In fig. 1, the signal processing apparatus 2 may include an analog signal processor 21, a digital-to-analog converter (D/a converter) 22, and a digital signal processor 23. The 2D MIMO array panel 1 transmits a detection signal in the form of a microwave millimeter wave to an object to be detected, and an echo signal generated after the detection signal reaches the object to be detected is received by the 2D MIMO array panel 1, which carries echo data corresponding to an equivalent phase center of the 2D MIMO array panel 10. The 2D MIMO array panel 1 transmits the echo signal to the analog signal processor 21. The analog signal processor 21 converts the received echo signal in the form of a power signal into an analog signal and sends it to the digital-to-analog converter 22. The digital-to-analog converter 22 converts the received analog signal into a digital signal and sends it to the digital signal processor 23. The digital signal processor 23 performs image reconstruction based on the received digital signal.

In some embodiments, the electromagnetic imaging device 10 may also include a distance measuring device 4. The ranging apparatus 4 may be mounted on the 2D MIMO array panel 1 for measuring a distance between the object to be inspected and the 2D MIMO array panel 1, as shown in fig. 1. The ranging apparatus 4 may be implemented by various distance detection devices including, but not limited to, a ranging radar, a proximity sensor, and the like. In the case where the ranging apparatus 4 is included, the signal processing apparatus 2 in the electromagnetic imaging apparatus 10 may reconstruct an image of the object to be detected from the distance between the object to be detected and the 2D MIMO array panel 1 detected by the ranging apparatus 4 and the echo signal received by the 2D MIMO array panel 1.

In some embodiments, the electromagnetic imaging apparatus 10 may further comprise a display apparatus 3, which may be connected to the signal processing apparatus 2, for displaying the image of the object to be examined reconstructed by the signal processing apparatus 2. The display apparatus 3 may be implemented as various devices having a display function, such as a display screen, a projector, and the like.

In some embodiments, the electromagnetic imaging apparatus 10 may further include an alarm device (not shown) connected to the signal processing device 2. In this case, the signal processing device 2 may also determine whether the object to be detected may contain a dangerous material based on a preset criterion from the reconstructed image of the object to be detected, and if so, control the alarm device to alarm. The alerting device may be implemented in various forms including, but not limited to, devices that sound an alarm such as a speaker, vibrator, alarm, etc., by audio, vibration, and various other means. An alarm level may also be set, for example, the signal processing device 2 may control the alarm device to alarm with a lower volume of sound or weaker vibration when the probability of containing a dangerous article is low, and control the alarm device to alarm with a higher volume of sound or stronger vibration when the probability of containing a dangerous article is high.

The structure of the 2D MIMO antenna array 11 in the 2D MIMO array panel 1 according to an embodiment of the present disclosure will be described below with reference to fig. 2 to 8. According to an embodiment of the present disclosure, a 2D MIMO antenna array may include a plurality of transmission antennas and a plurality of reception antennas arranged in an array, and the transmission antennas and the reception antennas may be mounted on a substrate, arranged in various forms as needed. The 2D MIMO antenna array may include at least one 2D MIMO sub-array, and a distance between adjacent transmitting antennas and/or adjacent receiving antennas in each 2D MIMO sub-array may be an integer multiple (e.g., 1, 2, 3, 4, 5, etc.) of a detection signal wavelength. The distance between adjacent equivalent phase centers may be half the wavelength of the detection signal. The size of the 2D MIMO antenna array may be designed to be the same as the imaging area, or slightly smaller or slightly larger than the imaging area, in order to ensure that the image of the object to be measured can be reconstructed correctly, for example, the side length of the entire 2D MIMO (i.e. a large array formed by stacking a plurality of MIMO sub-arrays) antenna array may be in the range of 10cm to 200 cm.

Fig. 2a and 2b (collectively fig. 2) respectively show a structural schematic diagram and an equivalent phase center schematic diagram of a 2D MIMO antenna array according to an embodiment of the present disclosure.

As shown in fig. 2a, the 2D MIMO antenna array includes a sub-array including two rows of transmitting antennas T arranged in a horizontal direction and two columns of receiving antennas R arranged in a vertical direction, the two rows of transmitting antennas T and the two columns of receiving antennas R forming a rectangular pattern. In fig. 2a, the size of the 2D MIMO antenna array may be 20cm × 20cm, the number of the transmitting antennas T and the receiving antennas R is 96, 96 respectively, and the number of the transmitting antennas T and the receiving antennas R is only illustrated for simplicity and is not an actual number.

As shown in fig. 2b, the equivalent position of the transmitted and received signals can be represented by the phase center of the antenna, which is the physical center of two independent antennas or apertures. In the embodiment of the present disclosure, the midpoint of the connecting line of the transmitting antenna and the corresponding receiving antenna is taken as the equivalent phase center of the two. In the MIMO architecture, one transmitting antenna T corresponds to multiple receiving antennas R, and in the embodiment of the present disclosure, the receiving antennas R and the transmitting antennas T are not arranged at the same position, and such a system with spatially separated transmitting and receiving antennas can be simulated by using a virtual system in which a virtual position is added between each set of transmitting antennas T and receiving antennas R, and this position is referred to as an equivalent phase center. The echo data collected by the receiving and transmitting antenna combination can be equivalent to the echo collected by the self-transmitting and self-receiving antenna at the position of the equivalent phase center.

In the 2D MIMO antenna array in fig. 2, the distances between adjacent transmitting antennas and adjacent receiving antennas are all the wavelengths λ of the detection signals, the distance between adjacent equivalent phase centers is λ/2, and the imaging sampling interval (i.e., the interval of the equivalent phase centers) is in the order of λ/2, so that there is no artifact superposition in the reconstructed image.

Fig. 3 shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure. As shown in fig. 3, the 2D MIMO antenna array 21 includes 2 × 2 sub-arrays, each sub-array is set to be 10cm × 10cm in size, the overall size of the 2D MIMO antenna array 21 is 20cm × 20cm, and the numbers of the transmission antennas T and the reception antennas R are 141, respectively.

Fig. 4 shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure. As shown in fig. 4, the 2D MIMO antenna array includes 3 × 3 sub-arrays, each sub-array having a size of 8cm × 8cm, the 2D MIMO antenna array 21 having an overall size of 24cm × 24cm, and the numbers of the transmission antennas T and the reception antennas R are 224 and 224, respectively.

Fig. 5 shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure. As shown in fig. 5, the 2D MIMO antenna array may include 2 × 3 sub-arrays, each having a size of 10cm × 10cm, the overall size of the 2D MIMO antenna array being 20cm × 30cm, and the numbers of transmit antennas T and receive antennas R being 188, 213, respectively.

Fig. 6 shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure. As shown in fig. 6, the 2D MIMO antenna array includes 2 × 4 sub-arrays, each sub-array having a size of 10cm × 10cm, the overall size of the 2D MIMO antenna array is 20cm × 40cm, and the numbers of transmit antennas and receive antennas are 285, 235, respectively.

In addition to using the 76-81GHz chip described above, (the control circuit of) the 2D MIMO array panel 1 may also be implemented as MIMO chips of other frequencies in the range of 10GHz-300 GHz. The side length of the 2D MIMO antenna array may be selected to be 10cm-50cm, preferably 20cm-40 cm. Table 1 shows the number of transmit antennas T and receive antennas R at different frequency bands for two different sub-array sizes with a total size of 30cm x 30cm for a 2D MIMO antenna array, where x denotes the center frequency. For example, as shown in table 1, for a 2D MIMO antenna array of 30cm × 30cm, if the sub-array size is 30cm × 30cm, the number of transmit antennas is 26 and the number of receive antennas is 26 for the detection signal in the 10GHz-20GHz band; if the size of the sub-array is 15cm multiplied by 15cm, the number of the transmitting antennas is 36, the number of the receiving antennas is 36, and the like, for the detection signals of the frequency band of 10GHz-20 GHz.

TABLE 1

Fig. 7a shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure. Fig. 7b shows a schematic diagram of an equivalent phase center of the 2D MIMO antenna array of fig. 8 a. As shown in fig. 7a, the 2D MIMO antenna array includes a sub-array including a row of transmitting antennas T arranged in a horizontal direction and a column of receiving antennas R arranged in a vertical direction, the row of transmitting antennas T and the row of receiving antennas R intersecting to form a cross-shaped pattern. As shown in fig. 7b, the equivalent phase centers of the 2d mimo antenna array of fig. 7a are distributed in the form of an array at the center of the cross-shaped pattern.

Fig. 8a shows a schematic structural diagram of a 2D MIMO antenna array according to another embodiment of the present disclosure. Fig. 8b shows a schematic diagram of an equivalent phase center of the 2D MIMO antenna array of fig. 8 a. As shown in fig. 8a, the 2D MIMO antenna array includes a sub-array including a row of transmitting antennas T arranged in a first diagonal direction of the array and a row of receiving antennas R arranged in a second diagonal direction of the array, the row of transmitting antennas T and the row of receiving antennas R intersecting to form a cross-shaped pattern in a diagonal form on the panel. As shown in fig. 8b, the equivalent phase center of fig. 8b is rotated 45 degrees (clockwise or counterclockwise) with respect to the equivalent phase center of fig. 7b because the 2D MIMO antenna array of fig. 8a is rotated 45 degrees with respect to the 2D MIMO antenna array of fig. 7 a.

It should be clear to those skilled in the art that the above is only an example, the structure of the 2D MIMO antenna array 11 of the present disclosure is not limited thereto, and the size of the sub-array, the size of the array, the arrangement of the antennas in the sub-array, and the number of antennas may be adjusted as needed.

The working principle of a 2D MIMO antenna array according to an embodiment of the present disclosure is described below with reference to fig. 9. As shown in fig. 9, a 2D MIMO antenna array including 4 × 4 sub-arrays is described as an example, in which each sub-array 101 has a structure as shown in fig. 2, and equivalent phase centers formed are arranged in the form of an array 102 (also referred to as an equivalent phase center net), (n) and_x，n_y) Representing the coordinates of the equivalent phase center in the array (equivalent phase center net). The central reference point of the imaging area 103 of the 2D MIMO antenna array is defined by

Indicating that the object to be inspected contains a reference point positioned at the center

Point scatterers at (a). When the safety detection is performed, the 2D MIMO antenna array may be controlled in an electronic scanning manner.

As an example, the control circuit may control the transmitting antennas in each sub-array of the 2D MIMO antenna array to sequentially transmit the detection signal, the receiving antennas to receive the echo signal, and then switch to the next sub-array, and repeat this operation until the whole antenna array scanning is completed, and all the scattering data of the detected object at different viewing angles are obtained. As another example, the control circuitry may control all transmit antennas in the 2D MIMO antenna array to transmit detection signals in turn and control all receive antennas in the 2D MIMO antenna array to receive echo signals. For the case where the 2D MIMO antenna array includes only one sub-array, a holographic reconstruction algorithm, which will be described below, may be employed for image reconstruction; in case the 2D MIMO antenna array comprises a plurality of sub-arrays, a back projection algorithm, which will be described below, may be employed for reconstruction.

In the embodiment of the disclosure, microwave and millimeter waves with the frequency in the range of 10-300GHz are used as detection signals, and the waves in the wave band have no ionization damage to a human body and can be used for human body security inspection. In the embodiment of the disclosure, the 2D MIMO antenna array includes a plurality of transmitting antennas and a plurality of receiving antennas arranged in a two-dimensional array, and works in an electronic scanning manner, and the electronic scanning has an advantage of a fast detection speed, and in combination with a three-dimensional holographic algorithm based on Fast Fourier Transform (FFT), real-time imaging can be achieved. One transmitting antenna and one corresponding receiving antenna in the 2D MIMO antenna array can generate an equivalent phase center, and echo data acquired by a pair of receiving and transmitting antenna combinations can be equivalent to echoes acquired by a self-transmitting and self-receiving antenna at the position of the equivalent phase center. The equivalent phase centers are arranged in an array, the interval between the adjacent equivalent phase centers is basically half of the wavelength lambda of the detection signal, so that the whole equivalent phase center array is basically a full array, and the sampling interval (namely the interval between the equivalent phase centers) adopted by the applied imaging system is in the order of lambda/2, therefore, no artifact superposition exists in the generated image, a clearer image can be formed, and the speed of image processing is improved.

The electromagnetic imaging apparatus according to the embodiment of the present disclosure may be installed in a security inspection device fixed in the field. In embodiments of the present disclosure, a security apparatus may be implemented in various different forms, and examples of the security apparatus according to embodiments of the present disclosure are described below with reference to fig. 10 to 16.

Fig. 10 shows a schematic diagram of a security device according to an embodiment of the present disclosure. The security inspection apparatus 110 includes a body and the electromagnetic imaging device 10 mounted in the body. In fig. 10, the body of the security check device 110 is a single counter that can be fixed for use in a suitable location, including but not limited to a hotel, hospital, etc. The body of the security inspection apparatus 110 includes a barrier 112 facing an object to be inspected (e.g., a visitor) and a tabletop 111 perpendicular to the barrier 112. The electromagnetic imaging apparatus 10 (specifically, a 2D MIMO array panel) is mounted on the barrier 112, for example, on the surface of the barrier 112 or inside the barrier 112, obtains information about an article carried by a visitor by transmitting a detection signal in the form of an electromagnetic wave to the visitor and receiving an echo signal from the visitor, and performs image reconstruction based on the echo signal, thereby achieving the purpose of security detection. The display device (not shown) of the electromagnetic imaging apparatus 10 may be installed at a position convenient for viewing, for example, may be disposed on a table top 111.

Fig. 11 shows a schematic view of a security device according to another embodiment of the present disclosure. The security check apparatus 120 of fig. 11 is similar to that of fig. 10 in that the body is also implemented in the form of a counter, at least in that the body of the security check apparatus 120 of fig. 11 includes a partition plate 123 parallel to the barrier 122 on the table top 121 in addition to the table top 121 and the barrier perpendicular to the table top 122. The isolation plate 123 may be made of a transparent material for isolating visitors and service personnel. The electromagnetic imaging apparatus 10 (specifically, a 2d mimo array panel) is mounted on the barrier 122. The body of the security check device 120 of fig. 11 may be fixedly installed in places requiring a higher security level, including but not limited to banks, government service agencies, and the like.

Fig. 12 shows a schematic view of a security device according to another embodiment of the present disclosure. The security inspection apparatus 130 of fig. 12 is similar to fig. 10 and 11, and the body of the security inspection apparatus 130 is also implemented in a single body, except at least that the body of the security inspection apparatus 130 of fig. 12 is implemented in the form of a single pillar having a sidewall 131 on which the electromagnetic imaging device 10 is mounted. In fig. 12, the body of the security inspection apparatus 130 is in the form of a rectangular column having four side walls 131, and one or more electromagnetic imaging devices 10 may be disposed on each of the four side walls 131. For example, one electromagnetic imaging device 10 may be disposed on each side panel, and the electromagnetic imaging device 10 may have a 2D MIMO array panel that may be spread over the entire column in one dimension as shown in fig. 12, and in some embodiments, may also have a plurality of 2D MIMO array panels, and the plurality of 2D MIMO array panels are spliced to form a 2D MIMO array panel that may be spread over the entire column in one dimension as shown in fig. 2. In some embodiments, a plurality of independent electromagnetic imaging devices 10 may be distributed on the column, for example, respectively disposed at different heights, for detecting different parts of, for example, a human body. Of course, the embodiments of the present disclosure are not limited thereto, and the number of the electromagnetic imaging devices 10 and the arrangement on the pillar may be selected according to the needs, for example, a plurality of electromagnetic imaging devices 10 arranged in other manners may be disposed on one or more of the four sidewalls 131. The electromagnetic imaging apparatus 10 may be installed on the outer surface, the inner surface of the sidewall 131, or embedded in the sidewall 131, or may be installed in the space defined by the sidewall 131. When the electromagnetic imaging device 10 is fully distributed on the whole post, a larger imaging area can be obtained, for example, the whole human body can be imaged, but not a part (for example, the waist) of the human body, so that more security check information can be obtained, and the security check level can be improved. As shown in fig. 12, the top of the pillar may be provided with decorations or installed with equipment such as a broadcasting station, a communication base station, and the like. The body of the security device 130 may be secured in a variety of suitable locations including, but not limited to, airports, office buildings, and the like.

Fig. 13 shows a schematic view of a security device according to another embodiment of the present disclosure. The security apparatus 140 of fig. 13 is similar to fig. 10 to 12, except at least that the body of the security apparatus 140 of fig. 13 is implemented in a separate form including a first portion 141 and a second portion 142 separated from each other, and the first portion 141 and the second portion 142 are each mounted with the electromagnetic imaging device 10. In fig. 13, the first and

second portions

141 and 142 are implemented in the form of doorposts fixed to both sides of a gate, and the electromagnetic imaging device 10 is mounted on the first and

second portions

141 and 142. In the example of fig. 13, the first portion 141 and the second portion 142 each include a pillar body located below and an ornament at the top of the pillar body, and a side of the electromagnetic imaging apparatus 10 mounted on the ornament at the top of the pillar body, which faces the object to be inspected, for example, the entrance side, may be located inside or outside the first portion 141 and the second portion 142. However, the embodiments of the present disclosure are not limited thereto, and in some embodiments, a plurality of electromagnetic imaging devices 10 may be installed on the whole doorpost, for example, the plurality of electromagnetic imaging devices 10 may be distributed on the whole doorpost, and may be respectively disposed toward four directions in a manner similar to that shown in fig. 12, and may of course be disposed toward other directions. The body of the security check device 140 may be fixed in a place where security needs to be secured, such as a kindergarten.

Fig. 14 shows a schematic view of a security device according to another embodiment of the present disclosure. The security inspection apparatus 150 of fig. 14 is similar to that of fig. 13, except that at least the body of the security inspection apparatus 150 of fig. 14 is implemented in the form of an escalator side wall including a first side wall 151 and a second side wall 152 facing each other, and the electromagnetic imaging device 10 is installed on a side of the second side wall 152 facing an object 153 to be inspected (e.g., a pedestrian), and it is possible to detect whether the object 153 to be inspected carries a hazardous article 154 by transmitting a detection signal to the object 153 to be inspected and receiving an echo signal from the object 153 to be inspected for image reconstruction.

Fig. 15 shows a schematic view of a security device according to another embodiment of the present disclosure. The security check device 160 of fig. 15 is similar to that of fig. 13, except at least that the body of the security check device 160 of fig. 15 is implemented in the form of a double stud, comprising a first stud 161 and a second stud 162. The electromagnetic imaging apparatus 10 is mounted in each of the first upright 161 and the second upright 162. In fig. 15, first upright 161 and second upright 162 are each a cylinder, and are respectively provided with a plurality of electromagnetic imaging devices 10 facing different directions, for example, four directions in a manner similar to that shown in fig. 12. However, the embodiments of the present disclosure are not limited thereto, and the number, arrangement, and orientation of the electromagnetic imaging devices 10 on the first and

second columns

161 and 162 may be set as needed, for example, a plurality of electromagnetic imaging devices 10 respectively oriented in five, six, or more directions may be set along a circular cross section of a cylinder. As another example, a passage for a pedestrian may be formed between the first upright 161 and the second upright 162, and the electromagnetic imaging apparatus 10 may be installed on a side of the first upright 161 and the second upright 162 facing the stream of people. The body of the security device 160 may be secured in any suitable location, for example as an ornament or support pole for an airport, hotel, or the like.

Fig. 16 shows a schematic view of a security device according to another embodiment of the present disclosure. The security check device 170 of fig. 16 is similar to that of fig. 13, except at least that the body of the security check device 170 of fig. 16 is implemented in the form of a ticket gate including a first gate 171 and a second gate 172, with a passage being formed between the first gate 171 and the second gate 172. The body of the security check device 170 may be fixed at any suitable place, such as a subway ticket gate, a train ticket gate, an office building entrance, and the like. The electromagnetic imaging device 10 is mounted in each of the first gate 171 and the second gate 172. In fig. 16, the electromagnetic imaging apparatus 10 may be installed at an inlet side of the first gate 171 and the second gate 172, for example, at a card swipe.

Fig. 17 shows a schematic flowchart of a control method of a security check device according to an embodiment of the present disclosure.

In step S101, the 2D MIMO antenna array 11 is controlled to transmit a detection signal to an object to be detected and receive an echo signal from the object to be detected. The 2D MIMO antenna array 11 may be controlled by the control circuit 12 to transmit detection signals to the object to be detected and receive echo signals, for example, in the manner described above. The detection signal may be an electromagnetic wave, such as a millimeter wave, specifically a millimeter wave terahertz wave.

In step S102, an image of the object to be measured is reconstructed from the received echo signals. For example, a global reconstruction algorithm or a back projection algorithm may be used to reconstruct an image of the object under test.

The holographic reconstruction algorithm can realize real-time reconstruction of the image of the detected object. The echo data collected by the pair of transceiving antenna combinations can be equivalent to the echo collected by the self-transmitting and self-receiving antenna at the position of the equivalent phase center. The signal processing device acquires echo data at the equivalent phase center, and assumes that the acquired reflection data of the object to be inspected is s (n)_x，n_y) And correcting the reflection data by using the following formula to obtain a corrected reflection data matrix:

wherein s (n)_x，n_y) For uncorrected scatter data matrix, n_xAnd n_yIs the position of the equivalent phase center in the equivalent phase center net (i.e., the index of the row and column).

R_u(n_x，n_y) And R_o(n_x，n_y) The calculation formula is as follows,

and is

In which, as shown in figure 9,

a reference point representing the center of the imaging region 103, j represents an imaginary number, and k represents a space constant.

R_u(n_x，n_y) Representing the calculated reflection set, in which case the object to be examined, containing a position fix, is sampled as shown in fig. 9

Point scatterers at (a).

R_o(n_x，n_y) Represents a computed reflection set that results when the equivalent phase-centric network of multiple-receive multiple-aperture is sampled (as shown in figure 9).

Then, reconstructing by using a two-dimensional Fourier transform algorithm to obtain a scattering coefficient of the detected object:

wherein I (x, y) represents the scattering coefficient of the object to be examined, z₀Represents the distance between the 2D MIMO array panel and the detected object, j represents an imaginary number, k is a propagation constant, k_x、k_yAre the spatial propagation constants, respectively; FFT_2DFor two-dimensional Fourier transform, IFFT_2DIs a two-dimensional inverse fourier transform.

After the two-dimensional aperture scan is completed, the acquired echo data can be represented as s (n)_x，n_y). And finally, combining a synthetic aperture holographic algorithm based on fast Fourier change to realize fast reconstruction and finish imaging. The purpose of the imaging algorithm is to invert the image of the detected object from the echo expression, namely the scattering coefficient I (x, y) of the detected object, and the synthetic aperture holographic algorithm based on Fourier transform does not need to reconstruct the whole imaging area point by point, but uses the advantage of fast Fourier transform to complete the reconstruction of the correct imaging area at one time. Therefore, the algorithm enables fast scanning and fast image reconstruction, and thus real-time imaging. The reconstructed image is displayed on a display device, and the suspicious object alarm algorithm is combined to alarm the suspicious object.

Backprojection originated from computed tomography technology, an accurate imaging algorithm based on time-domain signal processing. The basic idea is that for each imaging point in the imaging area, the time delay between the point to the receiving antenna and the transmitting antenna is calculated, and the contributions of all the echoes to the point are coherently superposed to obtain the corresponding pixel value of the point in the image, so that the coherent superposition processing is performed on the whole imaging area point by point, and the image of the imaging area can be obtained. The back projection algorithm is naturally easy to implement parallel computation, and therefore, is suitable for the case where the receiving antennas in a plurality of sub-arrays receive the reflected electromagnetic waves at the same time. Although reconstruction is required for each point in the whole imaging interval, if the hardware in the processing system adopts GPU or FPGA technology, the reconstruction time can be greatly reduced, and even real-time reconstruction is realized.

The reconstruction formula can be expressed as,

wherein the content of the first and second substances,

is the scattering coefficient, z, of the article to be measured_aIs the imaging distance, j is the unit of imaginary number, k is the propagation constant, s (x)_t，y_t，x_r，.y_rK) is the echo signal of the object to be measured received by a pair of transmitting antenna-receiving antenna combination, (x)_t，y_t) As the transmitting antenna coordinate, (x)_r，y_r) Z represents the distance between the 2D MIMO array panel and a certain fault of the object to be measured, and is the coordinate of the receiving antenna.

After step S102, other steps, such as analyzing the reconstructed image of the object to be detected to determine whether the object to be detected may carry dangerous goods, and if so, controlling the alarm device to alarm. For example, the reconstructed image of the object to be examined may be compared with a pre-stored template, and if the degree of matching with the feature template of a certain dangerous article is greater than a preset threshold, it is determined that the dangerous article is likely to be contained, otherwise, it is determined that the dangerous article is not contained. In some embodiments, the probability of containing dangerous goods may also be determined according to the degree of matching, for example, a higher degree of matching indicates a higher probability of containing dangerous goods, and a lower degree of matching indicates a lower probability of containing dangerous goods. Ways of alerting include, but are not limited to, visual display, audio alert, vibration alert, and the like. An alarm level may also be set, for example, when the probability of containing a dangerous article is low, an alarm may be given by a lower volume of sound or a weaker vibration, and when the probability of containing a dangerous article is high, an alarm may be given by a higher volume of sound or a stronger vibration.

In addition, the reconstructed image of the detected object and/or the judgment result can be presented to the user through the display device, for example, the reconstructed image can be displayed by using a display screen after the image is reconstructed, and then the analysis result is presented on the display screen; or the reconstructed image and the judgment result can be presented on a display screen after the image reconstruction and the analysis comparison are completed. The presentation mode of the determination result (for example, which dangerous goods may be contained or the probability of containing the dangerous goods) may be selected as required, and in addition to the above presentation in the form of a screen on the display screen, the determination result may be presented in other modes such as audio and vibration, for example, the determination result may be played in the form of voice, or the determination result may be indicated by the alarm volume or the vibration intensity of the alarm, for example, the alarm with high volume indicates that the dangerous goods are contained more likely, and the alarm with low volume indicates that the dangerous goods are contained less likely.

It will be appreciated by those skilled in the art that the embodiments described above are exemplary and can be modified by those skilled in the art, and that the structures described in the various embodiments can be freely combined without conflict in structure or principle.

Having described preferred embodiments of the present disclosure in detail, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope and spirit of the appended claims, and the disclosure is not limited to the exemplary embodiments set forth herein.

Claims

1. A security inspection apparatus including a body fixed in a field and an electromagnetic imaging device mounted on the body, the electromagnetic imaging device being mounted on an outer surface of a sidewall of the body, on an inner surface of the body, embedded within the sidewall of the body, or in a space defined by the sidewall, and on one or more sides of the body facing an object to be inspected, the electromagnetic imaging device comprising:

a two-dimensional multiple-transmission multiple-reception array panel having a length and a width both in a range of 10cm to 200cm, and comprising:

the signal processing device is connected with the two-dimensional multi-transmitting multi-receiving array panel and is used for reconstructing an image of the detected object according to the received echo signals; and

2. The security inspection device of claim 1, wherein a distance between adjacent transmit antennas and/or adjacent receive antennas in each two-dimensional multiple-transmit multiple-receive sub-array is an integer multiple of a wavelength corresponding to one of the plurality of frequencies of the detection signal, and a distance between adjacent equivalent phase centers is half the wavelength of the detection signal.

3. The security inspection device of claim 1, wherein each two-dimensional multiple-transmit multiple-receive sub-array includes two rows of transmit antennas arranged along a first direction and two columns of receive antennas arranged along a second direction perpendicular to the first direction, the two rows of transmit antennas and the two columns of receive antennas forming a rectangular pattern.

4. The security inspection apparatus of claim 1, wherein the two-dimensional multiple-transmit multiple-receive sub-array comprises a row of transmit antennas arranged along a first direction and a column of receive antennas arranged along a second direction perpendicular to the first direction, the rows and columns intersecting to form a cross shape.

5. The security inspection device of claim 1, wherein the control circuit is configured to control the plurality of transmit antennas in each two-dimensional multiple-transmit multiple-receive sub-array to transmit detection signals in sequence and to control the plurality of receive antennas in the two-dimensional multiple-transmit multiple-receive sub-array to receive echo signals; or the two-dimensional multi-transmission and multi-reception array panel is configured to control all transmitting antennas in the two-dimensional multi-transmission and multi-reception array panel to sequentially transmit detection signals and control all receiving antennas in the two-dimensional multi-transmission and multi-reception array panel to receive echo signals.

6. The security inspection apparatus according to any one of claims 1 to 5, wherein the body has an integral structure, and the electromagnetic imaging device is mounted on a side of the body facing the object to be inspected.

7. The security inspection apparatus according to any one of claims 1 to 5, wherein the body includes a first portion and a second portion separated from each other, a space between the first portion and the second portion for passing an object to be inspected therethrough, the electromagnetic imaging device being mounted on a side of the first portion and/or the second portion facing the object to be inspected.

8. The security device of any one of claims 1 to 5, wherein the detection signal is a microwave millimeter wave having a frequency in the range of 10-300 GHz.