Target detection method and security inspection device

Abstract

The present application provides a target detection method and security scanner, wherein a processing device receives a second signal that is reflected by a first signal emitted by a linear array antenna in the direction of a transmission device, and the processing device also receives a captured image captured by a camera. The processing device processes the captured image to obtain the actual position coordinates of the linear array antenna, and then images the second signal sent by the linear array antenna according to the actual position coordinates to obtain an image corresponding to the linear array antenna, thereby reducing the error in imaging caused by micro-movement of the human body and making imaging more accurate. The inspection object is transported by a conveyor belt, which reduces the residence time of the inspection object, and two linear array antennas are used to scan the inspection object at the same time, thereby improving the detection probability of hidden targets and the inspection efficiency.

Description

Technical Field

[0001] The present application relates to the field of security inspection technology, and in particular to a target detection method and a security inspection device. Background Art

[0002] Safety is a major issue in today's social development. It has become an indispensable task for countries to conduct body security checks on important places including important transportation hubs such as airports and government agencies. Body security inspection (Body Inspection) refers to a security inspection measure in specific places to check whether people are carrying prohibited items and dangerous items under their clothes and in their bodies.

[0003] At present, conventional human body security inspection systems include metal detection security inspection systems, X-ray human body security inspection systems and active millimeter wave security inspection systems. Among them, the active millimeter wave security inspection system actively transmits modulated electromagnetic wave signals, which are reflected to form echo signals, and then the received echo signals are imaged and processed to obtain security inspection images. Active millimeter wave security inspection systems mainly use linear array antennas or planar array antennas. Compared with planar array antennas, linear array antennas are less expensive and are widely used in millimeter wave security inspection systems.

[0004] However, since the linear array antenna uses a mechanical scanning method and obtains high-resolution images through two-dimensional aperture scanning, the inspected person needs to maintain a certain posture in the inspection area to facilitate two-dimensional aperture sampling. In addition, the inspected person needs to take off his coat and shoes before the inspection, which will result in a long inspection time, which can take up to tens of seconds or even minutes, greatly reducing the efficiency of security inspection. Summary of the invention

[0005] The present application provides a target detection method and a security scanner, which are used to solve the problem that the detection time of conventional millimeter wave security scanners is too long when inspecting targets, resulting in low efficiency.

[0006] In a first aspect, the present application provides a target detection method, using a security inspection device, the security inspection device comprising a transmission device, at least one linear array antenna, a camera and a processing device, the transmission device is used to transmit an object, and the method comprises:

[0007] The processing device receives a second signal returned by the linear array antenna, where the second signal is a signal returned after the first signal emitted by the linear array antenna in the direction of the transmitting device is reflected;

[0008] The processing device receives a captured image captured by the camera, wherein the captured image includes the transmission device and the measured object;

[0009] The processing device performs image analysis on the captured image to obtain the actual position coordinates of the linear array antenna;

[0010] The processing device performs imaging processing according to the actual position coordinates and the second signal to obtain an image corresponding to the linear array antenna.

[0011] Optionally, the linear array antenna includes a first linear array antenna and a second linear array antenna.

[0012] Optionally, the processing device performs image analysis on the captured image to obtain the actual position coordinates of the linear array antenna, including:

[0013] Acquire the position coordinates, coordinate rotation matrix and coordinate translation matrix of the linear array antenna in the antenna coordinate system according to the captured image, wherein the coordinate rotation matrix is ​​used to represent the rotation transformation parameters of the target coordinate system relative to the antenna coordinate system, and the coordinate translation matrix is ​​used to represent the translation transformation parameters of the target coordinate system relative to the antenna coordinate system, and the target coordinate system is the coordinate system where the measured target is located;

[0014] The actual position coordinates of the linear array antenna in the target coordinate system are calculated according to the position coordinates of the linear array antenna in the antenna coordinate system, the coordinate rotation matrix and the coordinate translation matrix.

[0015] Optionally, calculating the actual position coordinates of the linear array antenna in the target coordinate system according to the position coordinates of the linear array antenna in the antenna coordinate system, the coordinate rotation matrix, and the coordinate translation matrix includes:

[0016] The actual position coordinates are calculated according to the following formula:

[0017]

[0018] Among them, R is the coordinate rotation matrix, T is the coordinate translation matrix, (x 1 ,y 1 , z 1 ) is the actual position coordinate of the linear array antenna in the target coordinate system, and (x, y, z) is the position coordinate of the linear array antenna in the antenna coordinate system.

[0019] Optionally, the processing device performs imaging processing according to the actual position coordinates and the second signal to obtain an image corresponding to the linear array antenna, including:

[0020] interpolating and aligning the second signal returned by the linear array antenna with the actual position coordinates of the linear array antenna in terms of acquisition time;

[0021] Imaging processing is performed according to the actual position coordinates after interpolation processing and the second signal returned by the linear array antenna to obtain an image corresponding to the linear array antenna.

[0022] Optionally, performing imaging processing according to the actual position coordinates after interpolation processing and the second signal returned by the linear array antenna to obtain an image corresponding to the linear array antenna includes:

[0023] The actual distance between the linear array antenna and the measured target is calculated according to the following formula:

[0024]

[0025] Among them, (x 1 ,y 1 , z 1 ) is the actual position coordinate after interpolation processing, is the coordinate point of the measured target in the imaging result, and the actual distance is the distance calculated in the target coordinate system;

[0026] A third signal is obtained according to the actual distance and the second signal returned by the linear array antenna, and the third signal is expressed as:

[0027]

[0028] Among them, S(t, x 1 ,y 1 , z 1 ) is the third signal, is the coordinates in the imaging result, G(θ) is the antenna gain corresponding to the coordinates in the imaging result, t is the depth time, τ is the pulse width, f0 is the carrier frequency, K r is the frequency modulation slope, c is the speed of light, j is the complex number representation, W R , W x and W y Represent the time window functions in three directions respectively, is the set of target reflection coefficients in the imaging area, is the actual distance between the target linear array antenna and the measured target;

[0029] An image corresponding to the linear array antenna is obtained according to the third signal.

[0030] In a second aspect, the present application provides a security inspection device, including: a transmission device, at least one linear array antenna, a processing device and a camera;

[0031] The linear array antenna is arranged around the transmission device, and the radiation direction of the linear array antenna is toward the transmission device;

[0032] The conveying device comprises a conveyor belt for conveying objects located on the conveyor belt;

[0033] The linear array antenna is used to transmit a first signal in the direction of the transmission device, collect a second signal returned after the first signal is reflected, and send the second signal to the processing device;

[0034] The camera is arranged around the linear array antenna, the shooting direction of the camera is toward the transmission device, the camera is used to shoot an image and send the shot image to the processing device, the shot image includes the transmission device and the measured target;

[0035] The processing device is used to execute the method described in the first aspect.

[0036] Optionally, the security inspection device includes two linear array antennas: a first linear array antenna and a second linear array antenna.

[0037] Optionally, the first linear array antenna and the second linear array antenna are arranged on both sides of the transmission direction of the transmission device.

[0038] Optionally, the first linear array antenna and the second linear array antenna are arranged on one side of the transmission direction of the transmission device.

[0039] Optionally, a vertical distance between the first linear array antenna and the second linear array antenna and the transmission device is less than a preset distance.

[0040] In a third aspect, the present application provides a processing device, including:

[0041] A first receiving module is used to receive a second signal returned by the linear array antenna, where the second signal is a signal returned after the first signal emitted by the linear array antenna in the direction of the transmitting device is reflected;

[0042] A second receiving module is used to receive a captured image captured by the camera, wherein the captured image includes the transmission device and the measured object;

[0043] An analysis module, used for performing image analysis on the captured image to obtain the actual position coordinates of the linear array antenna;

[0044] A processing module is used to perform imaging processing according to the actual position coordinates and the second signal to obtain an image corresponding to the linear array antenna.

[0045] In a fourth aspect, the present application provides a processing device, comprising: a processor, and a memory communicatively connected to the processor;

[0046] The memory stores computer-executable instructions;

[0047] The processor executes the computer-executable instructions stored in the memory to implement the method according to the first aspect.

[0048] In a fifth aspect, the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and when the computer-executable instructions are executed by a processor, they are used to implement the method described in the first aspect.

[0049] In a sixth aspect, the present application provides a computer program product, including a computer program, which implements the method described in the first aspect when executed by a processor.

[0050] The present application provides a target detection method and security inspection instrument, which includes a transmission device, at least one linear array antenna, a camera and a processing device. The processing device receives a second signal returned after the first signal emitted by the linear array antenna in the direction of the transmission device is reflected. The processing device also receives a captured image obtained by the camera, and the captured image includes the transmission device and the target to be measured. The processing device performs image processing on the captured image to obtain the position information of the linear array antenna, and then images the second signal sent by the linear array antenna according to the position information to obtain an image corresponding to the linear array antenna, thereby reducing the error caused by micro-movement of the human body to the imaging, making the imaging more accurate. The inspection object is transported by a conveyor belt, which reduces the residence time of the inspection object, and two linear array antennas are used to scan the inspection object at the same time, which improves the detection probability of hidden targets and the security inspection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0052] Figure 1 Schematic diagram of the millimeter wave security inspection system using an array antenna;

[0053] Figure 2A A schematic diagram of a millimeter wave security inspection system using a linear array antenna;

[0054] Figure 2B A schematic diagram of another millimeter wave security inspection system using a linear array antenna;

[0055] Figure 3 A schematic diagram of the structure of a security inspection device provided in Example 1 of the present application;

[0056] Figure 4 A top view of a security inspection device provided in Example 1 of the present application;

[0057] Figure 5 A schematic diagram of a transmission device provided in Example 1 of the present application;

[0058] Figure 6 is a schematic diagram of a human body being located on a conveyor belt 1;

[0059] Figure 7 A schematic diagram of the structure of another security inspection device provided in the second embodiment of the present application;

[0060] Figure 8 A flowchart of a target detection method provided in Example 3 of the present application;

[0061] Fig. 9 is a schematic diagram of the target coordinate system and the antenna coordinate system;

[0062] Fig.10 It is the graph of coordinate translation matrix T and coordinate rotation matrix R changing with time;

[0063] Fig.11 It is a schematic diagram of the positions of the four key points in the antenna coordinate system;

[0064] Fig.12 The left picture in the figure is a hidden target in the detected target, and the right picture is a security inspection image formed according to the actual position coordinates and the second signal;

[0065] Fig.13 A comparison diagram of a security inspection image obtained by imaging the second signal without fusing the actual position coordinates (left) and a security inspection image obtained by imaging according to the actual position coordinates and the second signal (right);

[0066] Fig.14 A schematic diagram of the structure of a processing device provided in Embodiment 4 of the present application;

[0067] Fig.15 A schematic diagram of the structure of a processing device provided in Example 5 of the present application.

[0068] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0069] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0070] At present, conventional human body security inspection systems include metal detection security inspection systems, X-ray human body security inspection systems and active millimeter wave security inspection systems. Among them, the active millimeter wave security inspection system actively transmits modulated electromagnetic wave signals, which are reflected to form echo signals, and then the received echo signals are imaged to obtain security inspection images, and finally the detection of dangerous goods is achieved through manual image judgment or machine image recognition. Active millimeter wave security inspection systems mainly use linear array antennas or planar array antennas. Compared with planar array antennas, linear array antennas are less expensive and are widely used in millimeter wave security inspection systems. Figure 1 This is a schematic diagram of the millimeter wave security inspection system using a planar array antenna. Figure 2A This is a schematic diagram of a millimeter wave security inspection system using a linear array antenna. The sampling method of this system is electrical scanning in the altitude dimension and mechanical scanning in the azimuth dimension. Figure 2B This is a schematic diagram of another millimeter wave security inspection system using a linear array antenna. The sampling method of this system is mechanical scanning in the altitude dimension and electrical scanning in the azimuth dimension.

[0071] However, since the linear array antenna uses a mechanical scanning method and obtains high-resolution images through two-dimensional aperture scanning, the inspected person needs to maintain a certain posture in the detection area, that is, maintain a certain posture and remain still in the security inspection area for 2-10 seconds to facilitate two-dimensional aperture sampling. In addition, the inspected person needs to take off his coat and shoes before the inspection, which will result in a long inspection time, which can take up to tens of seconds or even minutes, greatly reducing the efficiency of security inspection.

[0072] Therefore, the target detection method and security scanner provided by the present application are arranged by arranging antennas around the conveying device and cameras around the antennas. The conveying device moves the target to be measured within the aperture illumination range of the antenna to replace the mechanical scanning of the azimuth dimension of the conventional millimeter wave security scanner, that is, the linear array antenna is fixed, and the target to be measured only needs to move with the conveyor belt, so that the antenna completes the scanning during the movement of the target to be measured, and the sampling data of two dimensions can be obtained, so that the camera completes the shooting to obtain the position information of the target to be measured, and finally the final security inspection image is obtained according to the sampling data and the position information, which reduces the error caused by the micro-movement of the human body to the imaging, and makes the imaging more accurate. The target to be measured does not need to remain in a static state for a certain period of time in the detection area to realize the detection of the security inspection object. The conveyor belt is used to transport the security inspection object, which reduces the residence time of the security inspection object, and two linear array antennas are used to scan the security inspection object at the same time, which improves the detection probability of hidden targets and the security inspection efficiency.

[0073] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments may exist independently or in combination with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0074] The security inspection apparatus of the present application includes at least one linear array antenna. The following embodiments 1 to 3 are described by taking two linear array antennas, namely, a first linear array antenna and a second linear array antenna, as examples.

[0075] Figure 3 A schematic diagram of the structure of a security inspection device provided in Example 1 of the present application is shown in FIG. Figure 3 A side view of the security inspection device provided in this embodiment, Figure 4 For a top view of the security inspection apparatus provided in this embodiment, refer to Figure 3 and Figure 4 The security scanner 10 includes a transmission device 303, a first linear array antenna 301, a second linear array antenna 302, a processing device 304 and a camera 307, wherein the first linear array antenna 301 is fixed on a first bracket 305, and the second linear array antenna 302 is fixed on a second bracket 306. The first linear array antenna 301 and the second linear array antenna 302 both include a plurality of transceiver sampling antennas (the portions indicated by black circles on the first linear array antenna 201 and the second linear array antenna 302 in FIG. 2 ), that is, a plurality of transceiver sampling antennas constitute a part of a linear array antenna.

[0076] The first linear array antenna 301 and the second linear array antenna 302 are arranged around the transmission device 303, and the radiation range of the first linear array antenna 301 and the second linear array antenna 302 is toward the transmission device 303. For example, Figure 4 As shown, the dotted line of the second linear array antenna 302 indicates that the area radiated by the electromagnetic waves emitted by the antenna is the radiation range, which is also called the aperture range of the antenna, and can be understood as the range that the electromagnetic waves emitted by the antenna can cover.

[0077] Optionally, the security inspection apparatus further includes a first bracket and a second bracket, the first linear array antenna 301 is fixed on the first bracket, and the second linear array antenna 302 is fixed on the second bracket. It can be understood that the bracket can also be integrated with the linear array antenna.

[0078] Exemplarily, the first linear array antenna 301 and the second linear array antenna 302 are arranged on both sides of the transmission direction of the transmission device 303, and the first linear array antenna 301 and the second linear array antenna 302 are at the same distance from the transmission device 303. Optionally, the line connecting the first linear array antenna 301 and the second linear array antenna 302 may be perpendicular to the transmission direction of the transmission device 303, that is, the first linear array antenna 301 and the second linear array antenna 302 are arranged opposite to each other. The line connecting the first linear array antenna 301 and the second linear array antenna 302 may also not be perpendicular to the transmission direction of the transmission device 303. When the aperture range of the antenna is large, the above two situations can enable the antenna to scan the range where the transmission device 303 is located.

[0079] It should be noted that the position of the linear array antenna may be in the middle of the conveying device 303 or not. The present application does not limit the placement of the linear array antenna. The position of the linear array antenna can maximize the effective radiation range of the linear array antenna. The effective radiation range is the radiation range including the conveying device 303 and the target to be measured on the conveyor belt.

[0080] The camera 307 is arranged around the first linear array antenna 301 and the second linear array antenna 302. The position of the camera 307 in the figure is only an example. The present embodiment does not limit the position of the camera 307. The camera 307 is arranged so that the camera's shooting range includes the transmission device 303 and the measured target on the transmission device 303. Moreover, the shooting direction of the camera 307 is toward the transmission device 303, and is used to shoot and obtain a shot image, and send the shot image to the processing device 304. The shot image includes the transmission device and the object on the transmission device, and the shot image is one frame of the video recorded by the camera 307. The present application needs to perform image analysis on each frame of the image.

[0081] It should be noted that the camera 307 can be a depth camera, a binocular camera, or a monocular camera set at multiple positions, and the captured images can be obtained. This application does not limit the type of camera 307.

[0082] The first linear array antenna 301 and the second linear array antenna 302 transmit the first signal respectively in the direction of the transmission device 303, specifically, transmit the first signal to the target under test located on the transmission device 303. The first signal may be an electromagnetic wave. After the first signal is reflected by the target under test, a second signal is formed. The first linear array antenna 301 and the second linear array antenna 302 may send the collected second signal to the processing device 304.

[0083] The processing device 304 can perform image analysis on the captured image sent by the camera 307 to obtain the actual position coordinates of the antenna, and then perform imaging processing based on the actual position coordinates and the second signal sent by the first linear array antenna 301 and the second linear array antenna 302 to obtain the first image corresponding to the first linear array antenna 301 and the second image corresponding to the second linear array antenna 302. The specific implementation can refer to Example 3. In the process of imaging the second signal, the actual position coordinates obtained by the camera are integrated, and not only the translation of the measured target in the azimuth and height directions, but also the rotation of the measured target in the depth direction are considered. That is, if the measured target has a slight movement on the conveyor belt, it will not affect the accuracy of the first image and the second image. This method reduces the error caused by micro-movement of the human body to the imaging, making the imaging more accurate.

[0084] The vertical distance between the first linear array antenna 301 and the second linear array antenna 302 and the transmission device 303 is less than a preset distance, which can be called a first preset distance. It can be understood that the distance between the transmission device and the antenna also needs to be greater than a certain distance to facilitate data collection. Exemplarily, the first preset distance can be 2 meters, and the vertical distance between the first linear array antenna 301 and the second linear array antenna 302 and the transmission device 303 can be in the range of 0.5 meters to 2 meters.

[0085] It should be noted that, since the processing device 304 is used to image the second signal, Figure 3 The position of the processing device 304 in the figure is only an example, and the present application does not limit the position of the processing device 304. The processing device 304 may also be a device independent of the security inspection machine, such as a server, etc. The security inspection machine 10 may also include a display device, and the processing device 304 may be located in the display device, which may display the imaged security inspection image, so that the security inspector can determine whether the detected object hides dangerous items.

[0086] The transmission device 303 is as follows Figure 5 As shown, the conveying device 303 includes a conveyor belt 1, which is used to convey an object located on the conveyor belt. The object may be a human body. For example, Figure 6 As shown, Figure 6 Schematic diagram of a human body on a conveyor belt 1, where the human body 308 can face the first linear array antenna 201 and face away from the second linear array antenna 302, and stand still on the conveyor belt 1. It should be noted that the present application does not limit the standing posture and direction of the human body, and in the case where the human body faces the first linear array antenna 301 and faces away from the second linear array antenna 302, the probability of the security scanner detecting a target hidden in the human body can be increased.

[0087] The conveying device 303 also includes a motor, which is used to control the movement of the conveyor belt to convey objects on the conveyor belt. It should be noted that the speed of the conveyor belt can be uniform or non-uniform, and this application does not limit this. Optionally, when the security scanner is used for human security inspection, the speed of the conveyor belt can be adjusted according to the flow of people in the application scenario of the security scanner, so that the conveying device of the security scanner of the present application can be an existing escalator and other facilities in application scenarios such as airports and stations, which can reduce costs.

[0088] It should be noted that the present application does not limit the structure of the transmission device. Figure 5 The transmission device in the figure is only an example, and the transmission device can be any structure that has the function of driving the target to be measured to move.

[0089] The security inspection device 10 provided in this embodiment is provided with a first linear array antenna 301 and a second linear array antenna 302 on both sides of a conveying device 303, and the radiation ranges of the two antennas are both toward the conveying device 303. The conveying belt in the conveying device 303 is used to convey the object on the conveying belt. The first linear array antenna 301 and the second linear array antenna 302 respectively transmit a first signal in the direction of the conveying device 303, and then collect a second signal returned after the first signal is reflected. The camera 307 is arranged around the first linear array antenna 301 and the second linear array antenna 302, and the shooting direction is toward the conveying device 303 to obtain the shooting image in the direction of the conveying device. The processing device 304 performs image processing on the shooting image received from the camera 307 to obtain the actual position coordinates of the antenna, and then performs imaging according to the actual position coordinates and the second signals sent by the first linear array antenna 301 and the second linear array antenna 302, to obtain the first image corresponding to the first linear array antenna 301 and the second image corresponding to the second linear array antenna 302, thereby reducing the error caused by micro-movement of the human body to the imaging, and making the imaging more accurate. The inspection objects are transported by conveyor belts, which reduces the residence time of the inspection objects. Two linear array antennas are used to scan the inspection objects at the same time, which improves the detection probability of hidden targets and the inspection efficiency.

[0090] Another security scanner provided by this application is introduced below.

[0091] Figure 7 This is a schematic diagram of the structure of another security inspection device provided in the second embodiment of the present application. Figure 7 It is a top view of the security scanner 70 , which includes a transmission device 703 , a first linear array antenna 701 and a second linear array antenna 702 . The first linear array antenna 701 and the second linear array antenna 702 can be arranged on one side of the transmission direction of the transmission device 703 .

[0092] The distance between the first linear array antenna 701 and the second linear array antenna 702 is less than the second preset distance. Exemplarily, the second preset distance may be 0.5 meters. When the distance between the two antennas is set to 0, the two antennas are placed close together.

[0093] The vertical distance between the first linear array antenna 701 and the second linear array antenna 702 and the transmission device 703 is also less than the first preset distance. The setting of the first preset distance can be the same as that of the security inspection device in the first embodiment.

[0094] In the security inspection device 70 of this embodiment, the angle between the radiation direction of the first linear array antenna 701 and the second linear array antenna 702 and the horizontal direction of the conveyor belt of the conveyor device 703 is 45 degrees. Figure 7 The dotted lines in the middle are respectively the radiation directions of the first linear array antenna 701 and the second linear array antenna 702. At this time, the target to be measured can be located on the conveyor belt facing the conveying direction of the conveyor belt. It can be understood that at this time, the first linear array antenna 701 can sample the front side of the target to be measured, and the second linear array antenna 702 can sample the back side of the target to be measured. That is, the first half of the distance that the target to be measured moves on the conveyor belt is scanned by the first linear array antenna 701, and the second half of the distance that the target to be measured moves on the conveyor belt is scanned by the second linear array antenna 702.

[0095] The first linear array antenna 701 and the second linear array antenna 702 respectively transmit the first signal along their respective radiation directions. Similarly, the first signal is reflected by the target to be measured to form a second signal. The first linear array antenna 701 and the second linear array antenna 702 can send the collected second signal to the processing device. The processing device is not Figure 7 As shown in the figure, the position of the processing device can refer to the placement position of the processing device of the security inspection device 10 in the first embodiment. The camera 707 can be arranged around the first linear array antenna 701 and the second linear array antenna to obtain a captured image including the conveying device 703 and the object on the conveying device 703. The position of the camera 707 in the figure is only an example, and this embodiment does not limit the position of the camera 707.

[0096] Similarly, the processing device can perform image analysis on the captured image sent by the camera 707 to obtain the actual position coordinates of the antenna, and then image the second signal sent by the first linear array antenna 701 and the second linear array antenna 702 respectively according to the actual position coordinates to obtain the first image corresponding to the first linear array antenna 701 and the second image corresponding to the second linear array antenna 702. For specific implementation, please refer to Example 3. It can be understood that when the target to be measured stands facing the conveying direction of the conveyor belt, the first image is the front image of the target to be measured, and the second image is the back image of the target to be measured.

[0097] The security inspection device 70 provided in this embodiment is provided with a first linear array antenna 701 and a second linear array antenna 702 on one side of a conveying device 703, and the radiation direction of the two antennas is at an angle of 45 degrees to the horizontal direction of the conveying belt of the conveying device 703. The conveying belt in the conveying device 703 transmits an object on the conveying belt, and the first linear array antenna 701 and the second linear array antenna 702 respectively transmit a first signal to the conveying device 703 in their respective radiation directions, and then collect a second signal returned after the first signal is reflected. The camera 707 is arranged around the first linear array antenna 701 and the second linear array antenna 702, and the shooting direction is toward the conveying device 703 to obtain a shot image in the direction of the conveying device. The processing device performs image processing on the shot image received from the camera 707 to obtain the actual position coordinates of the antenna, and then images the second signal received from the first linear array antenna 701 and the second linear array antenna 702 according to the actual position coordinates, and obtains the first image corresponding to the first linear array antenna 701 and the second image corresponding to the second linear array antenna 702, thereby reducing the error caused by micro-movement of the human body to the imaging, and making the imaging more accurate. The inspection objects are transported by conveyor belts, which reduces the residence time of the inspection objects. Two linear array antennas are used to scan the inspection objects at the same time, which improves the detection probability of hidden targets and the inspection efficiency.

[0098] In the security scanners of Example 1 and Example 2, the first linear array antenna and the second linear array antenna inherently detect the target to be measured on the conveying device, including altitude dimension electronic scanning and azimuth dimension electronic scanning. The azimuth dimension electronic scanning scans each position of the target to be measured moving along the conveyor belt, and the final security inspection image is obtained based on the data collected in two dimensions and the actual position coordinates of the antenna obtained by the camera.

[0099] The target detection method of the security inspection apparatus applied to the first or second embodiment is described below through the third embodiment.

[0100] Figure 8 A flow chart of a target detection method provided in Example 3 of the present application. The detection method of this embodiment is applied to the security scanner in Example 1 or Example 2. The security scanner includes a transmission device, at least one linear array antenna, a camera and a processing device. The method may include the following steps.

[0101] S801. A processing device receives a second signal returned by a linear array antenna, where the second signal is a signal returned after a first signal emitted by the linear array antenna in a direction of a transmitting device is reflected.

[0102] The first linear array antenna and the second linear array antenna both detect the detection area within their aperture ranges, that is, transmit a first signal in the direction of the conveying device, and the first signal can be an electromagnetic wave. The first linear array antenna and the second linear array antenna can both collect the second signal that is returned after the first signal is reflected by the measured target, and the second signal can be collected when the antenna remains stationary and the measured target moves with the conveyor belt, thereby reducing the time required for security inspection and improving security inspection efficiency. The processing device receives the second signal sent by the first linear array antenna and the second linear array antenna.

[0103] S802: The processing device receives an image captured by a camera, where the image includes the transmission device and the target to be measured.

[0104] Specifically, the camera records in the direction of the conveying device to obtain a recorded video, and the captured image is one frame of the recorded video. The captured image includes the conveying device and the target to be measured on the conveyor belt.

[0105] S803: The processing device performs image analysis on the captured image to obtain the actual position coordinates of the linear array antenna.

[0106] After receiving the captured image sent by the camera, the processing device can perform image analysis on the captured image. The specific analysis is as follows:

[0107] The processing device obtains the position coordinates of the first linear array antenna and the second linear array antenna in the antenna coordinate system based on the captured image, and then can perform key point detection on the target in the captured image, that is, use the existing key point detection model to process the captured image, such as the convolutional pose machine CPM (Convolutional Pose Machines, CPM for short) and other key point detection to further obtain the coordinate rotation matrix and the coordinate translation matrix. The coordinate rotation matrix is ​​used to represent the rotation transformation parameters of the target coordinate system and the antenna coordinate system, and the coordinate translation matrix is ​​used to represent the translation transformation parameters of the target coordinate system and the antenna coordinate system. The above-mentioned transformation parameters can also be obtained by methods such as target template matching and statistical processing of point cloud data. The present application does not limit the method of obtaining the transformation parameters. The above-mentioned target coordinate system is the coordinate system where the measured target is located, such as Fig. 9 As shown, the center of the target on the conveyor belt can be used as the origin of the target coordinate system, the conveying direction of the conveyor belt can be used as the x-axis, the direction facing the antenna can be used as the y-axis, and the vertical direction can be used as the z-axis.

[0108] Taking key point detection as an example, when the target to be detected in the image is a human body, the key points of the human skeleton can be obtained, that is, N key points of the target to be detected are determined, and these N key points are N of the pixel points in the captured image.

[0109] After determining the N key points, the coordinate rotation matrix and the coordinate translation matrix can be determined based on the three-dimensional coordinates of the N key points, and then the actual position coordinates of the first linear array antenna and the second linear array antenna in the target coordinate system can be calculated based on the position coordinates of the first linear array antenna and the second linear array antenna in the antenna coordinate system, the coordinate rotation matrix and the coordinate translation matrix. The following calculation is illustrated by taking four key points as an example, namely the left and right shoulders and the left and right abdomen of the human body. Since the target on the conveyor belt is not absolutely stationary, that is, the human target will have slight movements, then to determine the position of the target in space, it is necessary to clarify the six degrees of freedom of the target in space, namely the translational degrees of freedom of the target along the three rectangular coordinate axes of x, y, and z and the rotational degrees of freedom of the target around these three coordinate axes. The degree of freedom refers to a physical state described in physics.

[0110] like Fig. 9 As shown, O 1 -x 1 y 1 z 1 is the target coordinate system, O-xyz is the antenna coordinate system. The target coordinate system will move with the conveyor belt. The freedom of three-dimensional (height, azimuth and depth) rotation causes the inconsistency between the target coordinate system and the antenna coordinate system. The coordinates (x, y, z) of the target linear array antenna in the antenna coordinate system are converted to the coordinates (x 1 ,y 1 , z 1 )as follows:

[0111]

[0112] Among them, R is the coordinate rotation matrix, which includes three rotational degrees of freedom, and T is the coordinate translation matrix, which includes three translational degrees of freedom. 1 ,y 1 , z 1 ) is the actual position coordinate of the target linear array antenna in the target coordinate system, (x, y, z) is the position coordinate of the target linear array antenna in the antenna coordinate system, and the target linear array antenna is the first linear array antenna or the second linear array antenna.

[0113] According to formula (1), the actual position coordinates of the target linear array antenna in the target coordinate system can be determined as (x 1 ,y 1 , z 1 ).

[0114] Among them, the coordinate translation matrix T can be obtained by taking the average value of the three-dimensional coordinates of the above four key points. The coordinate rotation of the key points can be decomposed into rotations around three coordinate axes, as follows:

[0115] The key point i rotates around the Z axis by θ, which can be expressed as:

[0116]

[0117] The rotation of key point i around the X-axis ω can be expressed as:

[0118]

[0119] Key point i rotates around the Y axis It can be expressed as:

[0120]

[0121] Among them, i represents the key point, Represents the coordinates of the i-th key point in the target coordinate system. The coordinate rotation matrix R of each key point i =R1R2R3, which can be expressed as:

[0122]

[0123] Since the entire target is regarded as a rigid target, the rotation of a key point will also rotate all the key points. Therefore, the coordinate rotation matrix Ri of a key point can be used as the coordinate rotation matrix R of the target. Fig.10 is the time-varying graph of the coordinate translation matrix T and the coordinate rotation matrix R, that is, the change of the coordinate translation matrix T and the coordinate rotation matrix R when the measured target moves with the conveyor belt. The rotation angles θ, ω and It can be calculated by the following formula:

[0124]

[0125]

[0126]

[0127] Among them, (x i ,y i , z i ) is the coordinate of the i-th key point in the antenna coordinate system, z i is 0, such as Fig.11 As shown, the centroid of the quadrilateral formed by connecting the four key points can be used as the origin of the antenna coordinate system. For the convenience of describing the formula, ABCD is the coordinate of the x-axis and y-axis of the four key points in the target coordinate system, which are respectively expressed as (x1, y1), (x2, y2), (x3, y3) and (x4, y4). The coordinate of the centroid of the quadrilateral ABCD in the target coordinate system is It can be calculated by the following formula:

[0128]

[0129]

[0130] After obtaining the coordinates of the center of gravity, due to Fig. 9 The x-axis and y-axis of the two coordinate systems are in opposite directions, so the coordinates of the key point A in the antenna coordinate system (x A ,y A , O) is (y1-y g , x g -x1,0), the coordinates of key point B in the antenna coordinate system (x B ,y B ,0) is (y2-y g , x g -x2,0), the coordinates of the key point C in the antenna coordinate system (x C ,y C ,0) is (y3-y g , x g -x3,0), the coordinates of the key point D in the antenna coordinate system (x D ,y D ,0) is (y4-y g , x g -x4,0).

[0131] The coordinates (x i ,y i , 0) are substituted into formula (6), formula (7) and formula (8) respectively, and the rotation angles θ, ω and Substituting the rotation angle into formula (5) we can get the coordinate rotation matrix R i Then, by substituting the position coordinates (x, y, z) of the target linear array antenna in the antenna coordinate system, the coordinate rotation matrix R and the coordinate translation matrix T into formula (1), the actual position coordinates of the target linear array antenna in the target coordinate system can be obtained.

[0132] It should be noted that Fig.11 The shape of the quadrilateral in is only an example. The present application does not limit the shape of the quadrilateral. Moreover, there is no limit on the number N of key points. N can be any number greater than 3.

[0133] S804: The processing device performs imaging processing according to the actual position coordinates and the second signal to obtain an image corresponding to the linear array antenna.

[0134] After determining the actual position coordinates of the target linear array antenna in the target coordinate system, since each frame of image taken by the camera and the second signal returned by the antenna are not necessarily collected at the same time, for example, the camera collects a frame of image every 50 ms, and the antenna collects the second signal every 10 ms, then it is necessary to interpolate and align the second signal returned by the antenna with the actual position coordinates in the collection time, so that the second signals returned by the antenna have corresponding actual position coordinates. The interpolation calculation can be an average value or an algorithm such as bilinear interpolation.

[0135] The processing device can calculate the actual distance between the target linear array antenna and the measured target according to the following formula:

[0136]

[0137] Among them, (x 1 ,y 1 , z 1 ) is the actual position coordinate after interpolation processing, is the coordinate point of the measured target in the imaging result, and the actual distance is the distance calculated in the target coordinate system.

[0138] Then, the third signal is obtained according to the actual distance and the second signal returned by the target linear array antenna. The third signal can be expressed as:

[0139]

[0140] Among them, S(t, x 1 ,y 1 , z 1 ) is the third signal, G(θ) is the antenna gain, and in the antenna coordinate system, each coordinate (x i ,y i , z i ) corresponds to different antenna gains. This coefficient can generally range from 0 to 100. t is the depth time, τ is the pulse width, f0 is the carrier frequency, K r is the frequency modulation slope, c is the speed of light, j is the complex number representation, W is the time window function, W R , W x and W y Represent the time window functions in three directions respectively, represents the set of target reflection coefficients within the imaging area, σ n is the impulse function, (x n ,y n , z n ) is the actual position of the target linear array antenna in the target coordinate system.

[0141] The third signal of the azimuth dimension and the third signal of the altitude dimension both satisfy formula (12).

[0142] The processing device inputs the third signal of the azimuth dimension and the third signal of the altitude dimension into the imaging algorithm to obtain the image corresponding to the target linear array antenna, that is, obtains the first image corresponding to the first linear array antenna and the second image corresponding to the second linear array antenna. The imaging algorithm can be a time domain imaging algorithm.

[0143] It can be understood that the first image and the second image are security inspection images of different parts of the target to be detected. When the target to be detected faces the first linear array antenna and faces away from the second linear array antenna, the first image is a security inspection image of the front of the target to be detected, and the second image is a security inspection image of the back of the target to be detected, which further improves the probability of detecting hidden targets in the target to be detected. For example, Fig.12 The left picture in the figure is a hidden target in the target to be detected, and the right picture is a security inspection image imaged according to the actual position coordinates and the second signal. Fig.13 This is a comparison diagram between the security inspection image in which the second signal is imaged without integrating the actual position coordinates (left) and the security inspection image imaged based on the actual position coordinates and the second signal (right). It can be seen that the quality of the latter security inspection image is significantly better than the security inspection image in which the second signal is imaged without integrating the actual position coordinates.

[0144] In this embodiment, the processing device receives the second signal returned by the first linear array antenna and the second linear array antenna, which is the signal returned after the first signal emitted by the first linear array antenna and the second linear array antenna in the direction of the transmission device is reflected. The processing device also receives the captured image captured by the camera, and the captured image includes the transmission device and the target to be measured. The processing device performs image processing on the captured image to obtain the actual position coordinates of the first linear array antenna and the second linear array antenna, and then images the second signal sent by the first linear array antenna and the second linear array antenna according to the actual position coordinates to obtain the first image corresponding to the first linear array antenna and the second image corresponding to the second linear array antenna, thereby reducing the error caused by micro-movement of the human body to the imaging, making the imaging more accurate. The security inspection object is transported by a conveyor belt, which reduces the residence time of the security inspection object, and two linear array antennas are used to scan the security inspection object at the same time, thereby improving the detection probability of hidden targets and the security inspection efficiency.

[0145] refer to Fig.14 , Fig.14 This is a schematic diagram of the structure of a processing device provided in Example 4 of the present application. Fig.14 As shown, the processing device 140 includes: a first receiving module 1401 , a second receiving module 1402 , an analyzing module 1403 and a processing module 1404 .

[0146] The first receiving module 1401 is used to receive a second signal returned by the linear array antenna, where the second signal is a signal returned after the first signal emitted by the linear array antenna in the direction of the transmitting device is reflected.

[0147] The second receiving module 1402 is used to receive an image captured by a camera, where the image includes the transmission device and the target to be measured.

[0148] The analysis module 1403 is used to perform image analysis on the captured image to obtain the actual position coordinates of the linear array antenna.

[0149] The processing module 1404 is used to perform imaging processing according to the actual position coordinates and the second signal to obtain an image corresponding to the linear array antenna. Optionally, the analysis module 1403 is specifically used to:

[0150] The position coordinates, coordinate rotation matrix and coordinate translation matrix of the first linear array antenna and the second linear array antenna in the antenna coordinate system are obtained according to the captured image. The coordinate rotation matrix is ​​used to represent the rotation transformation parameters of the target coordinate system relative to the antenna coordinate system. The coordinate translation matrix is ​​used to represent the translation transformation parameters of the target coordinate system relative to the antenna coordinate system. The target coordinate system is the coordinate system where the measured target is located.

[0151] The actual position coordinates of the first linear array antenna and the second linear array antenna in the target coordinate system are calculated according to the position coordinates of the first linear array antenna and the second linear array antenna in the antenna coordinate system, the coordinate rotation matrix and the coordinate translation matrix.

[0152] Optionally, calculating actual position coordinates of the first linear array antenna and the second linear array antenna in the target coordinate system according to the position coordinates of the first linear array antenna and the second linear array antenna in the antenna coordinate system, the coordinate rotation matrix, and the coordinate translation matrix includes:

[0153] The actual position coordinates are calculated according to the following formula:

[0154]

[0155] Among them, R is the coordinate rotation matrix, T is the coordinate translation matrix, (x 1 ,y 1 , z 1 ) is the actual position coordinate of the target linear array antenna in the target coordinate system, (x, y, z) is the position coordinate of the target linear array antenna in the antenna coordinate system, and the target linear array antenna is the first linear array antenna or the second linear array antenna.

[0156] Optionally, the processing module 1404 is specifically configured to:

[0157] The second signal returned by the target linear array antenna is interpolated and aligned with the actual position coordinates of the target linear array antenna in terms of acquisition time.

[0158] Imaging processing is performed according to the actual position coordinates after interpolation processing and the second signal returned by the target linear array antenna to obtain an image corresponding to the target linear array antenna.

[0159] Optionally, performing imaging processing according to the actual position coordinates after interpolation processing and the second signal returned by the target linear array antenna to obtain an image corresponding to the target linear array antenna includes:

[0160] The actual distance between the target linear array antenna and the target to be measured is calculated according to the following formula:

[0161]

[0162] Among them, (x 1 ,y 1 , z 1 ) is the actual position coordinate after interpolation processing, is the coordinate point of the measured target in the imaging result, and the actual distance is the distance calculated in the target coordinate system.

[0163] The third signal is obtained according to the actual distance and the second signal returned by the target linear array antenna. The third signal is expressed as:

[0164]

[0165] Among them, S(t, x 1 ,y 1 , z 1 ) is the third signal, is any coordinate point of the measured target in the imaging result, G(θ) is the antenna gain corresponding to each coordinate in the imaging result, t is the depth time, τ is the pulse width, f0 is the carrier frequency, K r is the frequency modulation slope, c is the speed of light, j is the complex number representation, W R , W x and W y Represent the time window functions in three directions respectively, is the set of target reflection coefficients in the imaging area, is the actual distance between the target linear array antenna and the target being measured.

[0166] An image corresponding to the target linear array antenna is obtained according to the third signal.

[0167] The device of this embodiment can be used to execute a target detection method of the third embodiment. The specific implementation method and technical effect are similar and will not be described in detail here.

[0168] refer to Fig.15 , Fig.15A structural schematic diagram of a processing device provided in Example 5 of the present application, the device includes 150: a processor 1501, a memory 1502, and a transceiver 1503. The processor 1501 executes computer execution instructions stored in the memory 1502, and controls the receiving action and the sending action of the transceiver 1503, so that at least one processor executes a target detection method step of Example 3. The specific implementation method and technical effect are similar and will not be repeated here.

[0169] A computer-readable storage medium is provided in the sixth embodiment of the present application, and the computer-readable storage medium stores computer execution instructions. When the computer execution instructions are executed by a processor, they are used to implement the steps of a target detection method as in the third embodiment above. The specific implementation method and technical effect are similar and will not be repeated here.

[0170] A computer program product provided in Embodiment 7 of the present invention includes a computer program. When the computer program is executed by a processor, it implements the steps of a target detection method as in Embodiment 3 above. The specific implementation method and technical effect are similar and will not be repeated here.

[0171] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0172] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A target detection method, characterized in that: A security inspection device is used, the security inspection device includes a transmission device, at least one linear array antenna, a camera and a processing device, the transmission device is used to transmit an object, and the method includes: The processing device receives a second signal returned by the linear array antenna, where the second signal is a signal returned after the first signal emitted by the linear array antenna in the direction of the transmitting device is reflected; The processing device receives a captured image captured by the camera, wherein the captured image includes the transmission device and the measured object; The processing device performs image analysis on the captured image to obtain the actual position coordinates of the linear array antenna; The processing device performs imaging processing according to the actual position coordinates and the second signal to obtain an image corresponding to the linear array antenna; The processing device performs image analysis on the captured image to obtain the actual position coordinates of the linear array antenna, including: Acquire the position coordinates, coordinate rotation matrix and coordinate translation matrix of the linear array antenna in the antenna coordinate system according to the captured image, wherein the coordinate rotation matrix is ​​used to represent the rotation transformation parameters of the target coordinate system relative to the antenna coordinate system, and the coordinate translation matrix is ​​used to represent the translation transformation parameters of the target coordinate system relative to the antenna coordinate system, and the target coordinate system is the coordinate system where the measured target is located; The actual position coordinates of the linear array antenna in the target coordinate system are calculated according to the position coordinates of the linear array antenna in the antenna coordinate system, the coordinate rotation matrix and the coordinate translation matrix.

2. The method according to claim 1, characterized in that The calculating the actual position coordinates of the linear array antenna in the target coordinate system according to the position coordinates of the linear array antenna in the antenna coordinate system, the coordinate rotation matrix and the coordinate translation matrix comprises: The actual position coordinates are calculated according to the following formula: Among them, R is the coordinate rotation matrix, T is the coordinate translation matrix, (x 1 ,y 1 , z 1 ) is the actual position coordinate of the linear array antenna in the target coordinate system, and (x, y, z) is the position coordinate of the linear array antenna in the antenna coordinate system.

3. The method according to claim 2, characterized in that The processing device performs imaging processing according to the actual position coordinates and the second signal to obtain an image corresponding to the linear array antenna, including: interpolating and aligning the second signal returned by the linear array antenna with the actual position coordinates of the linear array antenna in terms of acquisition time; Imaging processing is performed according to the actual position coordinates after interpolation processing and the second signal returned by the linear array antenna to obtain an image corresponding to the linear array antenna.

4. The method according to claim 3, characterized in that The performing imaging processing according to the actual position coordinates after the interpolation processing and the second signal returned by the linear array antenna to obtain an image corresponding to the linear array antenna includes: The actual distance between the linear array antenna and the measured target is calculated according to the following formula: Among them, (x 1 ,y 1 , z 1 ) is the actual position coordinate after interpolation processing, is any coordinate point of the measured target in the imaging result, and the actual distance is the distance calculated in the target coordinate system; A third signal is obtained according to the actual distance and the second signal returned by the linear array antenna, and the third signal is expressed as: Among them, S(t, x 1 ,y 1 , z 1 ) is the third signal, is any coordinate point of the measured target in the imaging result, G(θ) is the antenna gain corresponding to each coordinate in the imaging result, t is the depth time, τ is the pulse width, f0 is the carrier frequency, K r is the frequency modulation slope, c is the speed of light, j is the complex number representation, w R 、w x and w y Represent the time window functions in three directions respectively, is the set of target reflection coefficients in the imaging area, is the actual distance between the linear array antenna and the measured target; An image corresponding to the linear array antenna is obtained according to the third signal.

5. A security inspection device, characterized in that: include: A transmission device, at least one linear array antenna, a processing device and a camera; The linear array antenna is arranged around the transmission device, and the radiation direction of the linear array antenna is toward the transmission device; The conveying device comprises a conveyor belt for conveying objects located on the conveyor belt; The linear array antenna is used to transmit a first signal in the direction of the transmission device, collect a second signal returned after the first signal is reflected, and send the second signal to the processing device; The camera is arranged around the linear array antenna, the shooting direction of the camera is toward the transmission device, the camera is used to shoot an image and send the shot image to the processing device, the shot image includes the transmission device and the measured target; The processing device is used to execute the method according to any one of claims 1 to 4.

6. The security inspection apparatus according to claim 5, characterized in that: The security inspection device comprises two linear array antennas: a first linear array antenna and a second linear array antenna.

7. The security inspection apparatus according to claim 6, characterized in that: The first linear array antenna and the second linear array antenna are arranged on both sides of a transmission direction of the transmission device.

8. The security inspection apparatus according to claim 6, characterized in that: The first linear array antenna and the second linear array antenna are arranged on one side of the transmission direction of the transmission device.

9. The security inspection apparatus according to claim 7 or 8, characterized in that: A vertical distance between the first linear array antenna and the second linear array antenna and the transmission device is less than a preset distance.

Images