CN115685131B

CN115685131B - Article detection method, detection device and detection system based on millimeter wave radar

Info

Publication number: CN115685131B
Application number: CN202310009686.XA
Authority: CN
Inventors: 栾禹辰; 陈龙永; 万阳良; 杨玲
Original assignee: Aerospace Information Research Institute of CAS
Current assignee: Aerospace Information Research Institute of CAS
Priority date: 2023-01-05
Filing date: 2023-01-05
Publication date: 2023-03-28
Anticipated expiration: 2043-01-05
Also published as: CN115685131A

Abstract

The invention provides an article detection method, a detection device and a detection system based on a millimeter wave radar. The method is applied to the technical field of millimeter wave radars, and comprises the steps of establishing two associated reference points in a distance-azimuth coordinate system, determining a target phase difference formula between the two reference points according to system parameters and an observation inclination angle of a first reference point observed by the millimeter wave radars, deducing the target phase difference formula to determine a pixel expression of any pixel in the distance-azimuth coordinate system, solving a target pixel expression of a multichannel signal by using the pixel expression, determining position information and height information of a target object in the multichannel signal according to a plurality of target pixel expressions, improving detection accuracy of the position and the height of the flat target object in a detection area, and reducing influence on flight of a spacecraft in the detection area due to the fact that the position and the height of the flat target object cannot be accurately obtained.

Description

Article detection method, detection device and detection system based on millimeter wave radar

Technical Field

The present invention relates to the technical field of millimeter wave radars, and more particularly, to an article detection method, an article detection device, and an article detection system based on a millimeter wave radar.

Background

The aircraft is quite fragile to foreign objects, a small piece of plastic cloth is sucked into an engine to possibly cause idle stop, a small screw or a metal sheet or even a sharp stone can puncture a tire to cause tire burst, and the generated tire fragments can damage the aircraft body or important parts such as a hydraulic pipe, an oil tank and the like. Items present on the airport runways may damage the aircraft or injure airport personnel and passengers, causing significant economic and personal injury.

In the related art, the object on the airport is detected by using the millimeter wave radar, the object is detected aiming at two-dimensional foreign objects in the direction and the distance direction, and when flat foreign objects on the airport pavement, such as glass fragments, metal tags and the like are placed on the pavement, even if the surface area of the flat foreign objects is large, the flat foreign objects are too flat, the cross section area of a backward scattering radar is small, the radar detection is difficult, and therefore the flat object on the airport is difficult to accurately detect.

Disclosure of Invention

In view of this, embodiments of the present invention provide an article detection method, an article detection apparatus, and an article detection system based on a millimeter wave radar.

One aspect of the embodiments of the present invention provides a method for detecting an article based on a millimeter wave radar, including:

determining a second reference point position corresponding to a first reference point position on a datum plane in a detection area in a distance-azimuth coordinate system, wherein a target distance between the first reference point position and an antenna phase of the millimeter wave radar is equal to a reference distance between the second reference point position and the antenna phase, and a height between the second reference point position and the datum plane is a preset height;

determining a first reference interference phase of the first reference point according to system parameters of the millimeter wave radar and an observation inclination angle of the millimeter wave radar for observing the first reference point, wherein the system parameters comprise a base length, a base inclination angle and a system working mode;

determining a target phase difference formula between the first reference point location and the second reference point location according to a viewing angle difference and the first reference interference phase, wherein the viewing angle difference is determined according to the preset height and represents a difference value of viewing angles of the first reference point location and the second reference point location observed by the millimeter wave radar respectively;

determining a pixel expression of any pixel in the distance-azimuth coordinate system according to the target phase difference formula;

processing the channel signals by using the pixel expressions aiming at any channel signal in multi-channel signals to obtain a plurality of target pixel expressions of the channel signals in the distance-azimuth coordinate system, wherein the multi-channel signals are obtained by observing a target object by using the millimeter wave radar;

and determining the position information and the height information of the target object according to a plurality of target pixel expressions corresponding to the multi-channel signals.

According to an embodiment of the present invention, the determining position information and height information of the target object according to a plurality of target pixel expressions corresponding to the multi-channel signal includes:

dividing a plurality of target pixel expressions into uniform discrete grids to obtain target expressions, wherein the target expressions are established according to a coefficient matrix and an observation matrix;

on the basis of a sparse perception theory, under the condition that the coefficient matrix is K sparse and the number of channels of the multi-channel signal is between K and the total number of the discrete grids, solving the target expression to obtain at least two target abscissa values;

determining a difference between the two target abscissa values as the height information;

the position information is determined based on a target pixel expression corresponding to each of the target abscissa values.

According to an embodiment of the present invention, the solving the target expression to obtain at least two target abscissa values includes:

solving the target expression and mapping the target expression in a peak coordinate system to obtain a plurality of phase points;

for each peak point in a plurality of phase points, determining the peak point as a target peak point when the phase of the peak point meets a preset threshold;

and determining the abscissa of each of the target peak points as one of the target abscissa values.

According to an embodiment of the present invention, the target expression is as shown in the first formula, and the target abscissa value is set in a case where no noise vector exists in the target expression

The calculation formula of (2) is shown as a second formula;

wherein,

，

the multi-channel signal is characterized in that,Ncharacterizing the number of channels;

the discrete grid is characterized in that it is,

characterizing a total number of meshes in the discrete mesh;

characterizing a time of the multi-channel signal;

characterization of

Observation matrix of dimensions, observation matrix

The expression of the matrix of the m-th dimension of the nth channel is

，

Is the effective baseline length of the nth channel,

；

is a noise vector;

and (5) characterizing the norm.

According to an embodiment of the present invention, the determining a target phase difference formula between the first reference point and the second reference point according to the viewing angle difference and the first reference interference phase includes:

determining the view angle difference according to the first reference point, the second reference point and the position of the millimeter wave radar in the distance-azimuth coordinate system;

determining a second reference interference phase according to the first reference interference phase and the view angle difference;

and determining the target phase difference formula according to the first reference interference phase and the second reference interference phase.

According to an embodiment of the present invention, the determining the target phase difference formula according to the first reference interference phase and the second reference interference phase includes:

determining an initial phase difference formula according to the first reference interference phase and the second reference interference phase;

and under the condition that the target distance is equal to the reference distance, optimizing the initial phase difference formula to obtain the target phase difference formula.

According to an embodiment of the present invention, the first reference interferometric phase

The second reference interference phase is expressed by the following first formula

The above initial phase difference formula is shown in the following second formula

The above target phase difference formula is shown in the following third formula

As shown in the fourth formula below, the pixel expression of any pixel

As shown in the following fifth formula;

wherein,

is the first reference point location, and is,

is a second reference point location;

in order to be the length of the base line,

as the angle of inclination of the baseline is,

is the observed inclination of the first reference point,

in order to transmit the wavelength of the signal,

the difference between the visual angles is used as the visual angle,

in order to be the target distance,

is a coefficient of the system operation mode, in case that the system operation mode is one-shot multiple-reception,

in the case of multiple sending and multiple receiving,

，

is a preset height;

wherein x and y are respectively the horizontal and vertical coordinates of the pixel;

is the total number of pixels in the detection area,

is the effective baseline length, the effective baseline is

，

Is the back-scattering coefficient of the point P,

is the distance from the point P to the reference plane,

and

the distance from the antenna phase to the boundary of the detection area and the observation angle,

in order to be a noise, the noise is,

in units of imaginary numbers.

According to an embodiment of the present invention, the determining, in the distance-azimuth coordinate system, the second reference point position corresponding to the first reference point position located on the reference plane in the detection area includes:

calibrating the antenna phase and the first reference point position in the range-azimuth coordinate system, wherein the first reference point position is located on an abscissa axis, and the abscissa axis represents the reference plane;

determining a plurality of initial reference points according to the target distance between the first reference point and the antenna phase of the millimeter wave radar;

and determining an initial reference point position having a height difference from the abscissa axis by the preset height among the plurality of initial reference point positions as the second reference point position.

Another aspect of the embodiments of the present invention provides an article detection apparatus based on a millimeter wave radar, including:

a first determining module, configured to determine, in a distance-azimuth coordinate system, a second reference point corresponding to a first reference point located on a reference plane in a detection area, where a target distance between the first reference point and an antenna phase of the millimeter wave radar is equal to a reference distance between the second reference point and the antenna phase, and a height between the second reference point and the reference plane is a preset height;

a second determining module, configured to determine a first reference interference phase of the first reference point according to system parameters of the millimeter wave radar and an observation inclination angle at which the millimeter wave radar observes the first reference point, where the system parameters include a baseline length, a baseline inclination angle, and a system operating mode;

a third determining module, configured to determine a target phase difference formula between the first reference point location and the second reference point location according to a viewing angle difference and the first reference interference phase, where the viewing angle difference is determined according to the preset height and represents a difference between viewing angles at which the millimeter wave radar respectively observes the first reference point location and the second reference point location;

a fourth determining module, configured to determine a pixel expression of any pixel in the distance-orientation coordinate system according to the target phase difference formula;

a processing module, configured to process, for any channel signal in a multichannel signal, the channel signal by using the pixel expression, and obtain multiple target pixel expressions of the channel signal in the range-azimuth coordinate system, where the multichannel signal is obtained by observing a target object by using the millimeter wave radar;

a fifth determining module, configured to determine position information and height information of the target object according to a plurality of target pixel expressions corresponding to the multi-channel signal.

Another aspect of an embodiment of the present invention provides an article detection system, including:

the millimeter wave radar is used for transmitting signals to a detection area and receiving multi-channel signals reflected by the detection area;

the electronic equipment comprises a processor, and the processor is used for executing the method so as to determine the position information and the height information of the target object in the detection area according to the multichannel signals received by the millimeter wave radar.

Another aspect of embodiments of the present invention provides a computer-readable storage medium storing computer-executable instructions for implementing a method as described above when executed.

Another aspect of embodiments of the present invention provides a computer program product comprising computer executable instructions for implementing a method as described above when executed.

According to the embodiment of the invention, two associated reference points are established in the distance-azimuth coordinate system, the first reference interference phase of the first reference point can be determined according to the system parameters and the observation inclination angle of the millimeter wave radar for observing the first reference point, the target phase difference formula between the two reference points is determined according to the first reference interference phase, the pixel expression of any pixel in the distance-azimuth coordinate system can be determined by deducing the target phase difference formula, the target pixel expression can be solved for the multichannel signal by utilizing the pixel expression, and the position information and the height information of the target object in the multichannel signal can be determined according to the plurality of target pixel expressions, so that the detection accuracy of the position and the height of the flat target object in the detection area is improved, and the influence on the flight of a spacecraft in the detection area caused by the fact that the position of the flat target object cannot be accurately obtained and the flight of the height of the spacecraft in the detection area is reduced.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 illustrates an exemplary system architecture to which a millimeter-wave radar-based item detection method may be applied, according to an embodiment of the present invention;

FIG. 2 shows a flow diagram of an item detection method according to an embodiment of the invention;

FIG. 3 illustrates a flow chart of location information and altitude information acquisition according to an embodiment of the present invention;

FIG. 4 shows a schematic diagram of a peak coordinate system according to an embodiment of the invention;

FIG. 5 shows a schematic diagram of a peak coordinate system according to another embodiment of the invention;

FIG. 6 shows a schematic diagram of a range-azimuth coordinate system in accordance with an embodiment of the invention;

FIG. 7 shows a block diagram of an item detection apparatus according to an embodiment of the present invention;

fig. 8 shows a block diagram of an electronic device adapted to implement the above described method according to an embodiment of the invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It is to be understood that such description is merely illustrative and not intended to limit the scope of the present invention. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the invention. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.

All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.

Where a convention analogous to "at least one of A, B and C, etc." is used, in general such a construction should be interpreted in the sense one having ordinary skill in the art would understand the convention (e.g., "a system having at least one of A, B and C" would include but not be limited to systems that have a alone, B alone, C alone, a and B, a and C, B and C, and/or A, B, C, etc.).

The embodiment of the invention provides an article detection method, a detection device and a detection system based on a millimeter wave radar. Determining a second reference point position corresponding to a first reference point position on a datum plane in a detection area in a distance-azimuth coordinate system, wherein a target distance between the first reference point position and an antenna phase of the millimeter wave radar is equal to a reference distance between the second reference point position and the antenna phase, and the height between the second reference point position and the datum plane is a preset height; determining a first reference interference phase of a first reference point position according to system parameters of the millimeter wave radar and an observation inclination angle of the millimeter wave radar for observing the first reference point position, wherein the system parameters comprise a base line length, a base line inclination angle and a system working mode; determining a target phase difference formula between the first reference point location and the second reference point location according to the visual angle difference and the first reference interference phase, wherein the visual angle difference is determined according to the preset height and represents the difference value of the visual angles of the first reference point location and the second reference point location observed by the millimeter wave radar respectively; determining a pixel expression of any pixel in a distance-orientation coordinate system according to a target phase difference formula; processing the channel signals by using pixel expressions aiming at any channel signal in the multichannel signals to obtain a plurality of target pixel expressions of the channel signals in a distance-azimuth coordinate system, wherein the multichannel signals are obtained by observing a target object by using a millimeter wave radar; position information and elevation information of the target item are determined based on a plurality of target pixel expressions corresponding to the multi-channel signal.

Fig. 1 illustrates an exemplary system architecture 100 to which a millimeter-wave radar-based item detection method may be applied, according to an embodiment of the present invention. It should be noted that fig. 1 is only an example of a system architecture to which the embodiments of the present invention may be applied, so as to help those skilled in the art understand the technical content of the present invention, and it does not mean that the embodiments of the present invention may not be applied to other devices, systems, environments or scenarios.

As shown in fig. 1, system architecture 100 according to this embodiment may include a first terminal device 101, a second terminal device 102, a third terminal device 103, a network 104, a server 105, and a millimeter wave radar 106. Network 104 is the medium used to provide communication links between

terminal devices

101, 102, 103 and server 105. Network 104 may include various connection types, such as wired and/or wireless communication links, and so forth.

The user may use the first terminal device 101, the second terminal device 102, the third terminal device 103 to interact with the server 105 via the network 104 to receive or send messages or the like. Various communication client applications, such as an article detection application, a shopping application, a web browser application, a search application, an instant messaging tool, a mailbox client, and/or social platform software, etc. (just examples), may be installed on the first terminal device 101, the second terminal device 102, and the third terminal device 103.

The first terminal device 101, the second terminal device 102, and the third terminal device 103 may be various electronic devices having a display screen and supporting web browsing, including but not limited to smart phones, tablet computers, laptop portable computers, desktop computers, and the like.

The server 105 may be a server that provides various services, such as a background management server that provides support for websites browsed by the user using the first terminal device 101, the second terminal device 102, and the third terminal device 103 (for example only). The backend management server may analyze and otherwise process data such as the received user request, and feed back a processing result (for example, a detection result or data generated by detecting an article in the detection area according to the user request) to the terminal device.

Millimeter wave radar 106 may include the installation base, installs the easy-to-break pole on the installation base to and install the radar main part on the easy-to-break pole, and the radar main part can be to detection area emission signal, and the multichannel signal that detection area reflects back can be received by the radar main part, and then can utilize the multichannel signal to carry out the detection of article.

It should be noted that the millimeter wave radar-based article detection method provided by the embodiment of the present invention may be generally executed by the server 105. Accordingly, the article detection apparatus provided by the embodiment of the present invention may be generally disposed in the server 105. The object detection method based on the millimeter wave radar provided by the embodiment of the present invention may also be executed by a server or a server cluster that is different from the server 105 and can communicate with the first terminal device 101, the second terminal device 102, the third terminal device 103, and/or the server 105. Accordingly, the article detection apparatus provided in the embodiment of the present invention may also be disposed in a server or a server cluster different from the server 105 and capable of communicating with the first terminal device 101, the second terminal device 102, the third terminal device 103 and/or the server 105. Alternatively, the object detection method based on millimeter wave radar provided in the embodiment of the present invention may also be executed by

terminal device

101, 102, or 103, or may also be executed by another terminal device different from

terminal device

101, 102, or 103. Accordingly, the article detection apparatus provided in the embodiment of the present invention may also be disposed in the first terminal device 101, the second terminal device 102, or the third terminal device 103, or disposed in another terminal device different from the first terminal device 101, the second terminal device 102, or the third terminal device 103.

It should be understood that the numbers of terminal devices, networks, servers, and millimeter wave radars in fig. 1 are merely illustrative. There may be any number of terminal devices, networks, servers, and millimeter wave radars, as desired for implementation.

FIG. 2 shows a flow diagram of an item detection method according to an embodiment of the invention.

As shown in fig. 2, the method for detecting an article based on a millimeter wave radar includes operations S201 to S206.

In operation S201, a second reference point location corresponding to a first reference point location on the reference plane in the detection area is determined in the range-azimuth coordinate system, where a target distance between the first reference point location and the antenna phase of the millimeter wave radar is equal to a reference distance between the second reference point location and the antenna phase, and a height between the second reference point location and the reference plane is a preset height.

In operation S202, a first reference interference phase of a first reference point location is determined according to system parameters of the millimeter wave radar and an observation inclination angle of the first reference point location observed by the millimeter wave radar, where the system parameters include a base length, a base inclination angle, and a system operating mode.

In operation S203, a target phase difference formula between the first reference point location and the second reference point location is determined according to the viewing angle difference and the first reference interference phase, where the viewing angle difference is determined according to the preset height, and the difference between the viewing angles of the first reference point location and the second reference point location is observed by the millimeter wave radar.

In operation S204, a pixel expression of any one pixel in the range-azimuth coordinate system is determined according to the target phase difference formula.

In operation S205, for any channel signal in the multi-channel signal, the channel signal is processed by using a pixel expression to obtain a plurality of target pixel expressions of the channel signal in the distance-orientation coordinate system, where the multi-channel signal is obtained by observing a target object by using a millimeter wave radar.

In operation S206, position information and height information of the target item are determined according to a plurality of target pixel expressions corresponding to the multi-channel signal.

According to an embodiment of the present invention, the detection area may refer to a runway, a taxiway, an apron, and the like of an airport. The Object may be Foreign Object Debris (FOD) such as pieces of metal, daily necessities, tools, stones, plastic, shells, and even wild animals such as birds, which may damage airplanes or injure workers and passengers in airports.

According to the embodiment of the invention, before the millimeter wave radar detects the detection area, a first reference point location and a second reference point location are determined in a distance-azimuth coordinate system, wherein the distances between the two reference points in the distance-azimuth coordinate system and the antenna phase of the millimeter wave radar are equal, the second reference point location is determined based on the preset height, and the first reference point location can be arranged on the abscissa axis of the distance-azimuth coordinate system.

According to the embodiment of the invention, the observation inclination angle of the millimeter wave radar for observing the first reference point is determined in the distance-azimuth coordinate system, the first reference interference phase of the first reference point P can be determined by combining the system parameters of the millimeter wave radar, such as the length of a base line, the inclination angle of the base line, the system working mode and the like, the viewing angle difference between the first reference point and the second reference point is respectively observed by combining the millimeter wave radar, the target phase difference formula between the first reference point and the second reference point can be obtained, and the pixel expression of any pixel in the distance-azimuth coordinate system can be obtained by deducing the target phase difference formula.

According to the embodiment of the invention, the multichannel signal acquired by the millimeter wave radar from the detection area

Of any channel signal

Mapped in the distance-orientation coordinate system, i.e. any channel signal is represented by pixel expression

A plurality of target pixel expressions may be obtained, and position information and height information for the target item may be determined based on the plurality of target pixel expressions corresponding to the multi-channel signal.

Fig. 3 shows a flowchart of acquiring position information and altitude information according to an embodiment of the present invention. FIG. 4 shows a schematic diagram of a peak coordinate system according to an embodiment of the invention. Fig. 5 shows a schematic diagram of a peak coordinate system according to another embodiment of the invention.

According to the embodiment of the invention, the position information and the height information of the target object are determined according to a plurality of target pixel expressions corresponding to the multi-channel signal, including operations S301-S304.

In operation S301, a plurality of target pixel expressions are divided into a uniform discrete grid to obtain a target expression, where the target expression is established according to a coefficient matrix and an observation matrix.

In operation S302, based on the sparse sensing theory, under the condition that the coefficient matrix is K sparse and the number of channels of the multi-channel signal is between K and the total number of the discrete grids, the target expression is solved to obtain at least two target abscissa values.

In operation S303, a difference between the two target abscissa values is determined as height information.

In operation S304, position information is determined according to the target pixel expression with each target abscissa value.

According to the embodiment of the invention, the sparse sensing theory indicates that when the signal can be sparsely represented, the original signal can be recovered by using a sampling signal far lower than the Nyquist sampling rate. The key of sparse reconstruction is to construct a proper observation matrix. Sparse reconstruction is to solve an underdetermined equation (the number of equations is less than that of unknown functions) under a certain condition, the millimeter wave radar ensures that the acquired signals x are sparse by arranging real apertures in the elevation direction, and only by solving the problem that an observation matrix meets the RIP (verified equation Property) condition, the underdetermined equation can be uniquely solved with a high probability.

According to the embodiment of the invention, a plurality of target pixel expressions are divided in a uniform discrete grid in a high direction

In the method, a target expression is obtained, and based on the sparse perception theory, under the condition that the coefficient matrix is K sparse and the number of channels of the multichannel signal is between K and the total number of the discrete grids, the target expression is solved to obtain at least two target abscissa values, as shown in fig. 4.

According to the embodiment of the present invention, in the case where the coefficient matrix is not K sparse, it is possible to obtain a peak coordinate system as shown in fig. 5, which indicates that the target object is not detected.

According to an embodiment of the present invention, after determining the two target abscissa values, a difference between the two target abscissa values is determined as the height information. And then, determining position information according to the target pixel expression of each target abscissa value, so that the position in the detection area where a target object with a certain thickness exists can be determined.

According to the embodiment of the invention, solving the target expression to obtain at least two target abscissa values comprises the following operations:

solving the target expression and mapping the target expression in a peak coordinate system to obtain a plurality of phase points; determining a peak point as a target peak point for each peak point in the plurality of phase points under the condition that the phase of the peak point meets a preset threshold; and determining the abscissa of each target peak point as a target abscissa value.

According to the embodiment of the present invention, the preset threshold may be selected according to actual situations, for example, 0.8 may be selected.

According to the embodiment of the present invention, in the process of solving the target expression, the solution result needs to be mapped in a peak coordinate system, and a plurality of phase points can be displayed in the peak coordinate system, wherein if a target article is detected, at least two peak points are displayed in the peak coordinate system, if the phase of the peak point meets a preset threshold, the peak point can be determined as one target peak point, and the height information of the target article is determined according to the target abscissa value of each target peak point, for example, in the case of a continuous target peak point, the target abscissa values of the two target peak points are subjected to subtraction processing, and the difference value is determined as the height information of the target article.

According to the embodiment of the present invention, in fig. 4, there is a phase point with a higher phase on the left side of two target peak points, and the phase point represents a certain clutter, but the phase point is not the target peak point because the phase of the phase point does not satisfy the preset threshold.

According to the embodiment of the present invention, the target expression is as shown in formula (1), and the target abscissa value in the case where there is no noise vector in the target expression

The calculation formula (2) is shown in formula (2);

（1）

（2）

wherein,

，

the discrete grid is characterized in that it is,

characterizing a total number of meshes in the discrete mesh;

characterizing a time of the multi-channel signal;

characterization of

Observation matrix of dimensions, observation matrix

The expression of the matrix of the m-th dimension of the nth channel is

，

Is the effective baseline length of the nth channel,

；

is a noise vector;

and (5) characterizing the norm.

FIG. 6 shows a schematic diagram of a range-azimuth coordinate system according to an embodiment of the invention.

According to an embodiment of the present invention, determining a target phase difference formula between a first reference point location and a second reference point location according to a viewing angle difference and a first reference interference phase comprises the following operations:

determining a view angle difference according to the first reference point position, the second reference point position and the position of the millimeter wave radar in the distance-azimuth coordinate system; determining a second reference interference phase according to the first reference interference phase and the view angle difference; and determining a target phase difference formula according to the first reference interference phase and the second reference interference phase.

According to an embodiment of the present invention, ginsengSee FIG. 6, in which

Being the centre of the antenna phase,

in order to be the length of the base line,

as the angle of inclination of the baseline is,

is the observed inclination of the first reference point.

According to an embodiment of the present invention, the difference in the viewing angle between the first reference point location and the second reference point location is determined based on the positions of the millimeter wave radar and the first reference point location in the range-azimuth coordinate system. A second reference interference phase may be determined from the first reference interference phase and the viewing angle difference. The target phase difference formula between the first reference interference phase and the second reference interference phase can be determined under the condition that the first reference interference phase and the second reference interference phase are determined.

According to an embodiment of the invention, determining the target phase difference formula from the first reference interference phase and the second reference interference phase comprises the operations of:

determining an initial phase difference formula according to the first reference interference phase and the second reference interference phase; and under the condition that the target distance is equal to the reference distance, optimizing the initial phase difference formula to obtain a target phase difference formula.

According to the embodiment of the invention, when the target phase difference formula is calculated, firstly, the initial phase difference formula is determined according to the first reference interference phase and the second reference interference phase, and the initial phase difference formula can be optimized to obtain the target phase difference formula because the target distance between the first reference point and the antenna phase of the millimeter wave radar is equal to the reference distance between the second reference point and the antenna phase.

According to an embodiment of the invention, the first reference interferometric phase

The second reference interference phase is shown in equation (3)

Initial phase difference formula as shown in formula (4)

The target phase difference formula

As shown in equation (6), the pixel expression of any pixel

As shown in equation (7);

（3）

（4）

（5）

（6）

（7）

wherein,

is the first reference point location, and is,

is a second reference point location;

in order to be the length of the base line,

the base line inclination angle is set as the base line inclination angle,

is the observed inclination of the first reference point,

in order to transmit the wavelength of the signal,

in order to obtain the difference between the visual angles,

is the distance to the target, and is,

in the case of multiple sending and multiple receiving,

，

is a preset height;

is the total number of pixels in the detection area,

is the effective baseline length, the effective baseline is

，

Is the back-scattering coefficient of the point P,

is the distance from the point P to the reference plane,

and

in order to be a noise, the noise is,

in units of imaginary numbers.

According to an embodiment of the present invention, the boundary refers to a boundary at which an intersection of an extension of the antenna phase and the first reference point and the detection area is located.

According to an embodiment of the present invention, determining a second reference point location in the detection area corresponding to the first reference point location located on the reference plane in the range-azimuth coordinate system includes the following operations:

calibrating the positions of an antenna phase and a first reference point position in a distance-azimuth coordinate system, wherein the first reference point position is located on an abscissa axis, and the abscissa axis represents a datum plane; determining a plurality of initial reference points according to the target distance between the first reference point and the antenna phase of the millimeter wave radar; and determining the initial reference point position with the height difference with the abscissa axis as the preset height from the plurality of initial reference point positions as a second reference point position.

According to the embodiment of the invention, when two reference point locations are marked in a distance-azimuth coordinate system, a first reference point location is firstly determined on an abscissa axis in the distance-azimuth coordinate system, a plurality of initial reference point locations are determined in the distance-azimuth coordinate system according to the distance between the first reference point location and one antenna phase, and according to a preset height, for example, 1m, which initial reference point location in the plurality of initial reference point locations is the preset height from the abscissa axis, and is determined as a second reference point location.

It should be noted that, when the method of the present invention is used to perform three-dimensional reconstruction of a pixel expression formula of a specific scene, in order to ensure the stability of the reconstruction result, a sufficient amount of information is required to eliminate uncertainty of the scene. A single scatterer (a target object of the present invention) corresponds to three unknowns, namely, amplitude, phase and height, and each channel signal can only obtain two measurement values of amplitude and phase, and in order to ensure that the sparse sensing theory has a unique solution, the number of the measurement values is required to be greater than or equal to the number of the scatterers, that is, formula (8).

（8）

Wherein,

the number of the channels is the same as the number of the channels,

the number of scatterers within a single pixel.

According to the embodiment of the invention, for airport foreign matters, the height of an object is low, most targets meet the condition that three target segments exist in the same distance and azimuth coordinate system, and the number of radar channels is not less than 5 to realize the resolution of the three segments. The array antenna of the millimeter wave radar selects a two-transmission three-reception working mode. In addition, the longer the baseline, the higher the resolution, if resolvedHas a height of

The lower base line length is shown in equation (9), and further, the longer the base line, the more the spatial view angle decorrelation is about severe, so the longest base line limit of the radar system is shown in equation (10). The rayleigh resolution of the height direction of the millimeter wave radar can thus be determined as shown in equation (11).

（9）

（10）

（11）

Wherein,

is the height of the radar in the radar,

in order to be the length of the base line,

in order to have a lower visual angle,

as the angle of inclination of the baseline is,

which is indicative of the wavelength of the emitted signal,

is the range resolution.

FIG. 7 shows a block diagram of an item detection apparatus according to an embodiment of the invention.

As shown in fig. 7, millimeter wave radar-based article detection apparatus 700 includes first determination module 710, second determination module 720, third determination module 730, fourth determination module 740, processing module 750, and fifth determination module 760.

The first determining module 710 is configured to determine, in a distance-azimuth coordinate system, a second reference point location corresponding to a first reference point location on a reference plane in the detection area, where a target distance between the first reference point location and an antenna phase of the millimeter wave radar is equal to a reference distance between the second reference point location and the antenna phase, and a height between the second reference point location and the reference plane is a preset height.

The second determining module 720 is configured to determine a first reference interference phase of the first reference point according to the system parameters of the millimeter wave radar and an observation inclination angle of the first reference point observed by the millimeter wave radar, where the system parameters include a baseline length, a baseline inclination angle, and a system operating mode.

The third determining module 730 is configured to determine a target phase difference formula between the first reference point location and the second reference point location according to the view angle difference and the first reference interference phase, where the view angle difference is determined according to the preset height, and represents a difference between viewing angles at which the millimeter wave radar respectively observes the first reference point location and the second reference point location.

The fourth determining module 740 is configured to determine a pixel expression of any pixel in the range-azimuth coordinate system according to the target phase difference formula.

The processing module 750 is configured to process the channel signals by using pixel expressions for any channel signal of the multi-channel signals, so as to obtain a plurality of target pixel expressions of the channel signals in the distance-direction coordinate system, where the multi-channel signals are obtained by observing a target object by using the millimeter wave radar.

A fifth determining module 760 for determining position information and height information of the target item according to a plurality of target pixel expressions corresponding to the multi-channel signal.

According to an embodiment of the present invention, the fifth determining module 760 includes a dividing unit, a solving unit, a first determining unit, and a second determining unit.

And the dividing unit is used for dividing the target pixel expressions into uniform discrete grids to obtain target expressions, wherein the target expressions are established according to the coefficient matrix and the observation matrix.

And the solving unit is used for solving the target expression to obtain at least two target abscissa values under the condition that the coefficient matrix is K sparse and the number of channels of the multi-channel signal is between K and the total number of the discrete grids based on the sparse perception theory.

A first determination unit for determining a difference between the two target abscissa values as the height information.

A second determination unit configured to determine the position information based on the target pixel expression with each of the target abscissa values.

According to an embodiment of the present invention, the solving unit includes an obtaining subunit, a first determining subunit, and a second determining subunit.

And the obtaining subunit is used for solving the target expression and mapping the target expression in a peak coordinate system to obtain a plurality of phase points.

The first determining subunit is used for determining the peak point as a target peak point under the condition that the phase of the peak point meets a preset threshold value for each peak point in the plurality of phase points.

And the second determining subunit is used for determining the abscissa of each target peak point as a target abscissa value.

According to an embodiment of the present invention, the third determining module 730 includes a third determining unit, a fourth determining unit, and a fifth determining unit.

And the third determining unit is used for determining the view angle difference according to the first reference point position, the second reference point position and the position of the millimeter wave radar in the distance-azimuth coordinate system.

And a fourth determination unit for determining the second reference interference phase according to the first reference interference phase and the viewing angle difference.

And the fifth determining unit is used for determining a target phase difference formula according to the first reference interference phase and the second reference interference phase.

According to an embodiment of the present invention, the fifth determining unit includes a third determining subunit and a fourth determining subunit.

And the third determining subunit is used for determining an initial phase difference formula according to the first reference interference phase and the second reference interference phase.

And the fourth determining subunit is used for optimizing the initial phase difference formula to obtain a target phase difference formula under the condition that the target distance is equal to the reference distance.

According to an embodiment of the present invention, the first determination module 710 includes a calibration unit, a sixth determination unit, and a seventh determination unit.

And the calibration unit is used for calibrating the antenna phase and the position of a first reference point position in a distance-azimuth coordinate system, wherein the first reference point position is located on an abscissa axis, and the abscissa axis represents a datum plane.

And the sixth determining unit is used for determining a plurality of initial reference points according to the target distance between the first reference point and the antenna phase of the millimeter wave radar.

And the seventh determining unit is configured to determine, as the second reference point, an initial reference point position of the plurality of initial reference point positions whose height difference from the abscissa axis is a preset height.

Any of the modules, units, sub-units or at least part of the functionality of any of them according to embodiments of the invention may be implemented in one module. Any one or more of the modules, units and sub-units according to the embodiments of the present invention may be implemented by being split into a plurality of modules. Any one or more of the modules, units, and sub-units according to the embodiments of the present invention may be implemented at least partially as a hardware Circuit, such as a Field Programmable Gate Array (FPGA), a Programmable Logic Array (PLA), a system on a chip, a system on a substrate, a system on a package, an Application Specific Integrated Circuit (ASIC), or may be implemented by hardware or firmware in any other reasonable manner for integrating or packaging a Circuit, or implemented by any one of or a suitable combination of software, hardware, and firmware. Alternatively, one or more of the modules, units, sub-units according to embodiments of the invention may be implemented at least partly as computer program modules which, when executed, may perform corresponding functions.

For example, any number of the first determining module 710, the second determining module 720, the third determining module 730, the fourth determining module 740, the processing module 750, and the fifth determining module 760 may be combined in one module/unit/sub-unit to be implemented, or any one of the modules/units/sub-units may be split into a plurality of modules/units/sub-units. Alternatively, at least part of the functionality of one or more of these modules/units/sub-units may be combined with at least part of the functionality of other modules/units/sub-units and implemented in one module/unit/sub-unit. According to an embodiment of the present invention, at least one of the first determining module 710, the second determining module 720, the third determining module 730, the fourth determining module 740, the processing module 750, and the fifth determining module 760 may be at least partially implemented as a hardware circuit, such as a Field Programmable Gate Array (FPGA), a Programmable Logic Array (PLA), a system on a chip, a system on a substrate, a system on a package, an Application Specific Integrated Circuit (ASIC), or may be implemented by hardware or firmware in any other reasonable manner of integrating or packaging a circuit, or implemented by any one of three implementations of software, hardware, and firmware, or by a suitable combination of any of them. Alternatively, at least one of the first determining module 710, the second determining module 720, the third determining module 730, the fourth determining module 740, the processing module 750 and the fifth determining module 760 may be at least partially implemented as a computer program module, which when executed, may perform a corresponding function.

It should be noted that, in the embodiment of the present invention, the part of the article detection apparatus based on the millimeter wave radar corresponds to the part of the article detection method based on the millimeter wave radar in the embodiment of the present invention, and the description of the part of the article detection apparatus based on the millimeter wave radar specifically refers to the part of the article detection method based on the millimeter wave radar, which is not described herein again.

Fig. 8 shows a block diagram of an electronic device adapted to implement the above described method according to an embodiment of the invention. The electronic device shown in fig. 8 is only an example, and should not bring any limitation to the functions and the scope of use of the embodiments of the present invention.

According to an embodiment of the present invention, an article detection system includes a millimeter wave radar and an electronic device. The millimeter wave radar is used for transmitting signals to a detection area and receiving multi-channel signals reflected by the detection area; the electronic device comprises a processor, and the processor is used for executing the method so as to determine the position information and the height information of the target object in the detection area according to the multichannel signals received by the millimeter wave radar. The electronic device may refer to a computer, a mobile phone, or other devices having an information processing function.

According to the embodiment of the invention, the two associated reference points are established in the distance-azimuth coordinate system, the first reference interference phase of the first reference point can be determined according to the system parameters and the observation inclination angle of the millimeter wave radar for observing the first reference point, the target phase difference formula between the two reference points is determined according to the first reference interference phase, the pixel expression of any pixel in the distance-azimuth coordinate system can be determined by deducing the target phase difference formula, the target pixel expression can be solved for the multichannel signal by utilizing the pixel expression, and the position information and the height information of the target object in the multichannel signal can be determined according to the plurality of target pixel expressions, so that the detection accuracy of the position and the height of the flat target object in the detection area is improved, and the influence of the position and the height of the flat target object, which cannot be accurately obtained, on the flight of a spacecraft in the detection area is reduced.

As shown in fig. 8, an electronic device 800 according to an embodiment of the present invention includes a processor 801 that can perform various appropriate actions and processes according to a program stored in a Read-Only Memory (ROM) 802 or a program loaded from a storage section 808 into a Random Access Memory (RAM) 803. The processor 801 may include, for example, a general purpose microprocessor (e.g., a CPU), an instruction set processor and/or associated chipset, and/or a special purpose microprocessor (e.g., an Application Specific Integrated Circuit (ASIC)), among others. The processor 801 may also include onboard memory for caching purposes. The processor 801 may comprise a single processing unit or a plurality of processing units for performing the different actions of the method flows according to embodiments of the present invention.

In the RAM 803, various programs and data necessary for the operation of the electronic apparatus 800 are stored. The processor 801, the ROM 802, and the RAM 803 are connected to each other by a bus 804. The processor 801 performs various operations of the method flow according to the embodiment of the present invention by executing programs in the ROM 802 and/or the RAM 803. Note that the programs may also be stored in one or more memories other than the ROM 802 and RAM 803. The processor 801 may also perform various operations of method flows according to embodiments of the present invention by executing programs stored in the one or more memories.

Electronic device 800 may also include input/output (I/O) interface 805, input/output (I/O) interface 805 also connected to bus 804, according to an embodiment of the invention. The system 800 may also include one or more of the following components connected to the I/O interface 805: an input portion 806 including a keyboard, a mouse, and the like; an output portion 807 including a Display such as a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and a speaker; a storage portion 808 including a hard disk and the like; and a communication section 809 including a network interface card such as a LAN card, a modem, or the like. The communication section 809 performs communication processing via a network such as the internet. A drive 810 is also connected to the I/O interface 805 as needed. A removable medium 811 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on the drive 810 as necessary, so that the computer program read out therefrom is mounted on the storage section 808 as necessary.

According to an embodiment of the invention, the method flow according to an embodiment of the invention may be implemented as a computer software program. For example, embodiments of the invention include a computer program product comprising a computer program embodied on a computer-readable storage medium, the computer program comprising program code for performing the method illustrated by the flow chart. In such an embodiment, the computer program can be downloaded and installed from a network through the communication section 809 and/or installed from the removable medium 811. The computer program, when executed by the processor 801, performs the above-described functions defined in the system of the embodiment of the present invention. The above described systems, devices, apparatuses, modules, units, etc. may be implemented by computer program modules according to embodiments of the present invention.

The present invention also provides a computer-readable storage medium, which may be contained in the apparatus/device/system described in the above embodiments; or may exist separately and not be assembled into the device/apparatus/system. The computer-readable storage medium carries one or more programs which, when executed, implement a method according to an embodiment of the invention.

According to an embodiment of the present invention, the computer readable storage medium may be a non-volatile computer readable storage medium. Examples may include, but are not limited to: a portable Computer diskette, a hard disk, a Random Access Memory (RAM), a Read-Only Memory (ROM), an Erasable Programmable Read-Only Memory (EPROM) or flash Memory), a portable compact Disc Read-Only Memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the preceding. In the present invention, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

For example, according to embodiments of the present invention, a computer-readable storage medium may include the ROM 802 and/or the RAM 803 described above and/or one or more memories other than the ROM 802 and the RAM 803.

Embodiments of the present invention also include a computer program product comprising a computer program containing program code for performing the method provided by embodiments of the present invention, when the computer program product is run on an electronic device, the program code being configured to cause the electronic device to implement the millimeter wave radar-based item detection method provided by embodiments of the present invention.

The computer program, when executed by the processor 801, performs the above-described functions defined in the system/apparatus of an embodiment of the present invention. The above described systems, devices, modules, units, etc. may be implemented by computer program modules according to embodiments of the invention.

In one embodiment, the computer program may be hosted on a tangible storage medium such as an optical storage device, a magnetic storage device, and the like. In another embodiment, the computer program may also be transmitted in the form of a signal on a network medium, distributed, downloaded and installed via communication section 809, and/or installed from removable media 811. The computer program containing program code may be transmitted using any suitable network medium, including but not limited to: wireless, wired, etc., or any suitable combination of the foregoing.

According to embodiments of the present invention, program code for executing a computer program provided by embodiments of the present invention may be written in any combination of one or more programming languages, and in particular, the computer program may be implemented using a high level procedural and/or object oriented programming language, and/or an assembly/machine language. The programming language includes, but is not limited to, programming languages such as Java, C + +, python, the "C" language, or the like. The program code may execute entirely on the user's computing device, partly on the user's device, partly on a remote computing device, or entirely on the remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computing device (e.g., through the internet using an internet service provider).

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams or flowchart illustration, and combinations of blocks in the block diagrams or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. It will be appreciated by a person skilled in the art that various combinations and/or combinations of features recited in the various embodiments of the invention and/or in the claims may be made, even if such combinations or combinations are not explicitly recited in the present invention. In particular, various combinations and/or combinations of the features recited in the various embodiments and/or claims of the present invention may be made without departing from the spirit and teachings of the invention. All such combinations and/or associations fall within the scope of the present invention.

The embodiments of the present invention have been described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Although the embodiments are described separately above, this does not mean that the measures in the embodiments cannot be used in advantageous combination. The scope of the invention is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the invention, and these alternatives and modifications are intended to fall within the scope of the invention.

Claims

1. An article detection method based on a millimeter wave radar is characterized by comprising the following steps:

determining a second reference point position corresponding to a first reference point position located on a datum plane in a detection area in a distance-azimuth coordinate system, wherein a target distance between the first reference point position and an antenna phase of the millimeter wave radar is equal to a reference distance between the second reference point position and the antenna phase, and a height between the second reference point position and the datum plane is a preset height;

determining a target phase difference formula between the first reference point location and the second reference point location according to a visual angle difference and the first reference interference phase, wherein the visual angle difference is determined according to the preset height and represents a difference value of visual angles of the first reference point location and the second reference point location observed by the millimeter wave radar respectively;

determining a pixel expression of any pixel in the distance-orientation coordinate system according to the target phase difference formula;

2. The method of claim 1, wherein said determining position information and elevation information of said target item from a plurality of said target pixel expressions corresponding to said multi-channel signal comprises:

on the basis of a sparse perception theory, under the condition that the coefficient matrix is K sparse and the number of channels of the multichannel signal is between K and the total number of the discrete grids, solving the target expression to obtain at least two target abscissa values;

and determining the position information according to the target pixel expression of each target abscissa value.

3. The method of claim 2, wherein solving the target expression for at least two target abscissa values comprises:

for each peak point in the plurality of phase points, determining the peak point as a target peak point under the condition that the phase of the peak point meets a preset threshold value;

and determining the abscissa of each target peak point as one target abscissa value.

4. The method according to claim 3, wherein the target expression is as shown in formula (1), and the target abscissa value is the target abscissa value in the absence of a noise vector in the target expression

The calculation formula (2) is shown in formula (2);

（1）

（2）

wherein,

，/>

the multi-channel signal is characterized in that,Ncharacterizing the number of channels; />

The discrete grid is characterized in that it is,

characterizing a total number of meshes in the discrete mesh; />

Characterization->

Observation matrix of dimensions, observation matrix->

The expression of the matrix in the mth dimension of the nth channel is @>

，/>

Is the effective baseline length of the nth channel>

； />

Is a noise vector; />

And (5) characterizing the norm.

5. The method of claim 1, wherein determining a target phase difference formula between the first reference point location and the second reference point location based on the viewing angle difference and the first reference interference phase comprises:

determining the view angle difference according to the first reference point position, the second reference point position and the position of the millimeter wave radar in the distance-azimuth coordinate system;

6. The method of claim 5, wherein said determining the target phase difference formula from the first reference interference phase and the second reference interference phase comprises:

7. The method of claim 6, wherein the first reference interferometric phase

The second reference intervention phase ≧ as represented by equation (3)>

The initial phase difference formula->

The target phase difference formula->

The pixel expression ^ for any pixel, as shown in equation (6)>

As shown in equation (7);

（3）

（4）

（5）

（6）

（7）

wherein,

is the first reference point, <' > is selected>

Is a second reference point location; />

Is the length of the base line, is greater or less than>

Is the base inclination angle->

Is the observed inclination of the first reference point, <' > is>

For emitting a signal wavelength>

For the difference in angle of vision, in combination with a plurality of light sources>

Is the target distance->

Is a coefficient of the system working mode, and is based on the condition that the system working mode is one-shot multi-receiving>

In the case of multiple sending and multiple receiving,

， />

is a preset height;

wherein x and y are respectively the horizontal and vertical coordinates of the pixel; />

Is the total number of pixels in the detection area->

Is the effective baseline length, the effective baseline is->

， />

Is the backscattering coefficient at point P->

Is the distance from the point P to the reference plane,

and &>

Respectively, the distance from the antenna phase to the boundary of the detection region and the observation angle>

Is a noise, is asserted>

In units of imaginary numbers.

8. The method of claim 3, wherein determining a second reference point location in the detection area corresponding to the first reference point location on the datum surface in the range-azimuth coordinate system comprises:

calibrating the positions of the antenna phase and the first reference point position in the distance-azimuth coordinate system, wherein the first reference point position is located on an abscissa axis, and the abscissa axis represents the datum plane;

and determining the initial reference point position with the height difference with the abscissa axis as the preset height among the plurality of initial reference point positions as the second reference point position.

9. An article detection device based on millimeter wave radar, characterized by comprising:

the first determining module is used for determining a second reference point position corresponding to a first reference point position located on a datum plane in a detection area in a distance-azimuth coordinate system, wherein a target distance between the first reference point position and an antenna phase of the millimeter wave radar is equal to a reference distance between the second reference point position and the antenna phase, and the height between the second reference point position and the datum plane is a preset height;

the second determining module is used for determining a first reference interference phase of the first reference point according to system parameters of the millimeter wave radar and an observation inclination angle of the millimeter wave radar for observing the first reference point, wherein the system parameters comprise a base length, a base inclination angle and a system working mode;

a third determining module, configured to determine a target phase difference formula between the first reference point location and the second reference point location according to a view angle difference and the first reference interference phase, where the view angle difference is determined according to the preset height and represents a difference between viewing angles at which the millimeter wave radar respectively observes the first reference point location and the second reference point location;

the fourth determining module is used for determining a pixel expression of any pixel in the distance-orientation coordinate system according to the target phase difference formula;

the processing module is used for processing the channel signals by using the pixel expressions aiming at any channel signal in the multichannel signals to obtain a plurality of target pixel expressions of the channel signals in the distance-azimuth coordinate system, wherein the multichannel signals are obtained by observing a target object by using the millimeter wave radar;

a fifth determining module, configured to determine position information and height information of the target item according to a plurality of target pixel expressions corresponding to the multi-channel signal.

10. An item detection system, comprising:

an electronic device comprising a processor configured to perform the method of any of claims 1~8 to determine position information and elevation information of a target item in the detection area from the multichannel signal received by the millimeter wave radar.