An imaging method and device for a distributed microwave radar

Abstract

The present application discloses a distributed microwave radar imaging method and apparatus. The method includes: obtaining a first echo signal received by a first microwave radar, where the first microwave radar is disposed at a first height; obtaining a second echo signal received by a second microwave radar, where the second microwave radar is disposed at a second height, and the first height is lower than the second height; determining a first radar imaging result image of a detection target based on the first echo signal; determining a second radar imaging result image of the detection target based on the second echo signal; and fusing the first radar imaging result image and the second radar imaging result image to obtain a target fusion image. The present application can achieve high-resolution imaging of the overall detection target.

Description

Technical Field

[0001] This application relates to the field of radar signal processing, and particularly to an imaging method and device for a distributed microwave radar. Background Art

[0002] A microwave radar is a radar that operates in the microwave band, usually referring to the frequency range of 100M - 200GHz. The working range of a microwave radar is 1mm - 1m, which is divided into millimeter waves, centimeter waves, decimeter waves, etc. Its working principle is to emit a microwave detection signal towards the target object, and then compare the received signal reflected from the target object with the emitted detection signal. After signal processing, relevant information about the target object is obtained, such as parameters like target distance, azimuth, speed, attitude, shape, structure, size, etc.

[0003] Among them, a millimeter - wave radar refers to a radar that operates in the millimeter - wave band. Usually, millimeter waves refer to electromagnetic waves in the frequency range of 30 - 300GHz (wavelength of 1 - 10mm). The wavelength of millimeter waves is between centimeter waves and light waves, so millimeter waves have the advantages of both microwave guidance and optoelectronic guidance. Millimeter waves have a wide range of applications in fields such as 5G communication, satellite remote sensing, missile guidance, and electronic countermeasures. In recent years, with the continuous improvement of component levels and the increasing development and maturity of related technologies such as circuit design and antenna technology, the application of millimeter - wave radars in the field of road detection and automotive autonomous driving has also achieved great development.

[0004] However, in the fields of road detection and automotive autonomous driving, millimeter - wave radars are mainly used for ranging or speed measurement of single - point targets, and high - resolution two - dimensional imaging has not been achieved.

[0005] Currently, using synthetic aperture radar technology (SAR) with a side - looking observation mode can achieve radar imaging processing. Conventional radar imaging algorithms include: Range Doppler Algorithm (RDA), Range Migration Algorithm (RMA), Back Projection Algorithm (BPA), Frequency Scaling Algorithm (FSA), etc.

[0006] However, during the application of the above algorithm in side-looking perception imaging, the inherent echo aliasing problem of SAR radar cannot be overcome, so there are imaging blind spots for the observed targets. The echo aliasing problem means that the sampling point positions of targets that are symmetric with respect to the radar height fall into the same sampling unit because of the same time delay to reach the radar, resulting in aliasing. Therefore, the imaging resolution of the observed targets is relatively low. Summary of the Invention

[0007] In order to improve the imaging resolution of a radar imaging device for a detection target, the present application provides an imaging method and device for a distributed microwave radar.

[0008] In a first aspect, an embodiment of the present application provides a distributed microwave radar imaging method, which includes: obtaining a first echo signal received by a first microwave radar, where the first microwave radar is set at a first height; obtaining a second echo signal received by a second microwave radar, where the second microwave radar is set at a second height, and the first height is lower than the second height; determining a first radar imaging result image of the detection target based on the first echo signal; determining a second radar imaging result image of the detection target based on the second echo signal; and fusing the first radar imaging result image and the second radar imaging result image to obtain a target fusion image.

[0009] In this implementation, since the distributed microwave radar imaging realizes the complementary characteristics of high and low viewing angles, it can not only measure the length information of the detection target, but also solve the problem of inconsistent resolution in the height dimension of the detection target, realizing high-resolution imaging of the overall detection target.

[0010] Moreover, because the imaging results of the high and low radars are fused, and the partial images with echo aliasing problems are cropped, the influence brought by the echo aliasing problem is eliminated, and the imaging resolution of the detection target is improved.

[0011] In a possible design, the determining a first radar imaging result image of the detection target based on the first echo signal includes: determining a first initial radar imaging image of the detection target based on the first echo signal; performing a first geometric deformation correction on the first initial radar imaging image to obtain a first radar imaging result image; the determining a second radar imaging result image of the detection target based on the second echo signal includes: determining a second initial radar imaging image of the detection target based on the second echo signal; and performing a second geometric deformation correction on the second initial radar imaging image to obtain a second radar imaging result image.

[0012] In this implementation, by performing geometric deformation correction on the preliminary radar imaging image, the influence caused by the foreshortening phenomenon during the side-looking perception imaging process is eliminated. The foreshortening phenomenon causes geometric deformation distortion in the initial radar imaging image, and the imaging resolution of the detection target is improved through geometric deformation correction.

[0013] In a possible design, the first geometric deformation correction includes: determining a first variation relationship between the first imaging width and the height of the detection target based on the height of the first microwave radar and the shortest distance between the first microwave radar and the detection target, where the first variation relationship is a non-linear functional relationship; performing interpolation processing based on the first variation relationship to determine the first radar imaging result image; where the first imaging width of the detection target is the distance from the first microwave radar to the vertex of the detection target minus the shortest distance; the second geometric deformation correction includes: determining a second variation relationship between the imaging width and the height of the detection target based on the height of the second microwave radar and the shortest distance between the second microwave radar and the detection target, where the second variation relationship is a non-linear functional relationship; performing interpolation processing based on the second variation relationship to determine the second radar imaging result image; where the second imaging width of the detection target is the distance from the second microwave radar to the bottom point of the detection target minus the shortest distance.

[0014] In this implementation, the ratio between the height of the detection target and the operating distance of the microwave radar is relatively large. Using non-linear transformation in the slant range projection is more accurate than the traditional linear stretching scheme in the remote sensing field and can more accurately describe the slant range projection result of the detection target. Therefore, the imaging resolution of the detection target is improved.

[0015] In a possible design, fusing the first radar imaging result image and the second radar imaging result image to obtain a target fusion image includes: splicing and fusing the upper part imaging area corresponding to the detection target in the first radar imaging result image and the lower part imaging area corresponding to the detection target in the second imaging result image to obtain the target fusion image.

[0016] In a possible design, the lower boundary of the upper part imaging area and the upper boundary of the lower part imaging area correspond to the reference line of the detection target.

[0017] In this implementation, by splicing and fusing the high and low perspective radar imaging result images, the high-resolution parts of the two radar imaging results are selected for fusion, overcoming the problem of inconsistent resolution in the height dimension direction, thereby improving the overall imaging resolution of the image.

[0018] In a possible design, after performing the fusion of the first radar imaging result image and the second radar imaging result image to obtain a target fusion image, it further includes: determining the external shape information or structural information of the detection target based on the target fusion image.

[0019] In a possible design, the external shape information includes the two-dimensional size or three-dimensional solid size of the detection target.

[0020] In this implementation manner, the external shape information or structural information of the detection target is determined based on the target fusion image, thereby obtaining accurate target feature information, improving the imaging resolution, and facilitating subsequent further processing of the detection target.

[0021] In a second aspect, an embodiment of the present application provides a distributed microwave radar imaging device, including: a first acquisition unit that acquires a first echo signal received by a first microwave radar, where the first microwave radar is disposed at a first height; a second acquisition unit that acquires a second echo signal received by a second microwave radar, where the second microwave radar is disposed at a second height, and the first height is lower than the second height; a first imaging unit that determines a first radar imaging result image of the detection target based on the first echo signal; a second imaging unit that determines a second radar imaging result image of the detection target based on the second echo signal; and a target fusion unit that fuses the first radar imaging result image and the second radar imaging result image to obtain a target fusion image.

[0022] In a possible design, the first imaging unit is specifically configured to: determine a first initial radar imaging image of the detection target based on the first echo signal; perform first geometric deformation correction on the first initial radar imaging image to obtain a first radar imaging result image; the second imaging unit is specifically configured to: determine a second initial radar imaging image of the detection target based on the second echo signal; perform second geometric deformation correction on the second initial radar imaging image to obtain a second radar imaging result image.

[0023] In a possible design, the first geometric deformation correction includes: determining a first variation relationship between the first imaging width and the height of the detection target based on the height of the first microwave radar and the shortest distance between the first microwave radar and the detection target, where the first variation relationship is a non-linear functional relationship; performing interpolation processing based on the first variation relationship to determine the first radar imaging result image; where the first imaging width of the detection target is the distance from the first microwave radar to the vertex of the detection target minus the shortest distance; the second geometric deformation correction includes: determining a second variation relationship between the imaging width and the height of the detection target based on the height of the second microwave radar and the shortest distance between the second microwave radar and the detection target, where the second variation relationship is a non-linear functional relationship; performing interpolation processing based on the second variation relationship to determine the second radar imaging result image; where the second imaging width of the detection target is the distance from the second microwave radar to the bottom point of the detection target minus the shortest distance.

[0024] In a possible design, the target fusion unit is specifically configured to: splice and fuse the upper part imaging area corresponding to the detection target in the first radar imaging correction image and the lower part imaging area corresponding to the detection target in the second imaging correction image to obtain a target fusion image.

[0025] In a possible design, the lower boundary of the upper part imaging area and the upper boundary of the lower part imaging area correspond to the reference line of the detection target.

[0026] In a possible design, it further includes a target shape determination unit, and the target shape determination unit is specifically configured to: determine the shape information or structural information of the detection target based on the target fusion image.

[0027] In a possible design, the shape information includes the two-dimensional size or three-dimensional solid size of the detection target.

[0028] In a third aspect, an embodiment of the present application provides a distributed microwave radar imaging system, including a first microwave radar, a second microwave radar, and the device according to any item in the second aspect.

[0029] In a fourth aspect, an embodiment of the present application provides a roadside microwave radar imaging system, including a first microwave radar, a second microwave radar, and the device according to any item in the second aspect, where the first microwave radar and the second microwave radar are arranged on the roadside, and the detection target is a vehicle.

[0030] In a fifth aspect, an embodiment of the present application provides a vehicle, including a first microwave radar, a second microwave radar, and the device according to any item in the second aspect, where the first microwave radar and the second microwave radar are arranged on the vehicle.

[0031] In a sixth aspect, an embodiment of the present application provides a computer-readable storage medium storing a computer program for executing the imaging method according to any one of the first aspect.

[0032] In a seventh aspect, an embodiment of the present application provides a computer program product which, when running on a computer, causes the computer to execute the imaging method according to any one of the first aspect.

[0033] In an eighth aspect, an embodiment of the present application provides an electronic device including: a processor; a memory for storing executable instructions of the processor; and the processor for executing the control method of the target object according to any one of the first aspect.

[0034] In a ninth aspect, an embodiment of the present application provides a chip including at least one processor, the processor being coupled to a memory, and the processor for reading instructions in the memory and executing the method according to any one of the first aspect according to the instructions.

[0035] It can be understood that any of the distributed microwave radar imaging devices, readable storage media, computer program products, imaging systems, vehicles, and electronic devices provided above can be implemented by the corresponding methods provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding methods provided above, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of an application scenario provided by an embodiment of the present application;

[0037] Figure 2 It is a schematic structural diagram of a microwave radar imaging system provided by an embodiment of the present application;

[0038] Figure 3 It is a schematic flowchart of a distributed microwave radar imaging method provided by an embodiment of the present application;

[0039] Figure 4 It is a schematic flowchart of a method for determining a first radar imaging result based on a first echo signal provided by an embodiment of the present application;

[0040] Figure 5a It is a schematic diagram of the actual size of a vehicle provided by an embodiment of the present application;

[0041] Figure 5b It is a schematic diagram of a first radar initial imaging result provided by an embodiment of the present application;

[0042] Figure 5c It is a schematic diagram of a second radar initial imaging result provided by an embodiment of the present application;

[0043] Figure 6 Schematic diagram of the imaging width of the detection target by the first microwave radar provided by the embodiment of the present application;

[0044] Figure 7a Schematic diagram of the first radar imaging result provided by the embodiment of the present application;

[0045] Figure 7b Schematic diagram of the second radar imaging result provided by the embodiment of the present application;

[0046] Figure 8 Schematic flowchart of the specific method for the first geometric deformation correction provided by the embodiment of the present application;

[0047] Figure 9 Schematic diagram of the change curve of the imaging width and height of the detection target provided by the embodiment of the present application;

[0048] Figure 10 Schematic diagram of the imaging width of the detection target by the second microwave radar provided by the embodiment of the present application;

[0049] Figure 11 Schematic diagram of the external dimension direction of the detection target provided by the embodiment of the present application;

[0050] Figure 12 Schematic geometric diagram of the three-dimensional dimensions of the detection target provided by the embodiment of the present application;

[0051] Figure 13 Schematic diagram of the structure of a distributed microwave radar imaging device provided by the embodiment of the present application. Detailed implementation manners

[0052] To make the objectives, technical solutions, and advantages of the present application clearer, the following will further describe the implementation manners of the present application in detail with reference to the accompanying drawings.

[0053] Before explaining the embodiments of the present invention in detail, first, the terms involved in the embodiments of the present invention will be described.

[0054] Synthetic Aperture Radar (SAR) is a radar system that operates in a pulsed mode. The variations of its signals along the range direction and the azimuth direction are different. The variation along the range direction is rapid, while the variation along the azimuth direction is slow. For SAR sensing and imaging, the specific imaging mechanism is as follows: In the azimuth direction, by continuously transmitting chirp signals to the observation area, a virtual long synthetic aperture array is formed, that is, high resolution for imaging is achieved in the azimuth direction using the synthetic aperture principle; in the range direction, by transmitting ultra-wideband chirp signals and obtaining high range resolution through pulse compression technology, a two-dimensional high-resolution radar sensing image is obtained. The range direction is perpendicular to the direction of the detected target's movement, and the azimuth direction is the direction of the detected target's movement. Synthetic Aperture Radar is an active microwave imaging method with a certain degree of penetration, capable of capturing more target information that is not easily detected in optical images all day and all weather, and has a good reconnaissance effect.

[0055] The frequency of a Frequency Modulated Continuous Wave (FMCW) signal is a function of time. Two widely used frequency modulation forms are sawtooth wave frequency modulation and triangular wave frequency modulation. Taking the FMCW signal with sawtooth wave frequency modulation as an example, the frequency of the transmitted signal changes linearly with time in a sawtooth pattern. The target echo is a replica of the transmitted waveform, and the two-way echo delay τ = 2R / C, where R is the target distance and C is the speed of light. During the modulation period, the beat frequency is positive in some parts and negative in some parts, and the negative beat frequency part in the sweep period is very small because the maximum echo delay usually set is very small compared to the sweep period.

[0056] In recent years, the combination of FMCW technology and SAR technology has led to the birth of a high-resolution imaging radar with light weight, low cost, and low power consumption.

[0057] FMCW SAR generally transmits a large time-bandwidth product chirp signal (and the transmitted signal occupies nearly the entire pulse repetition period) to achieve high resolution in the range direction. On the one hand, considering that traditional pulsed SAR usually adopts direct sampling, different from traditional pulsed SAR, FMCW SAR generally adopts the Dechirp receiving method. This is because the sweep period of FMCW SAR reaches the millisecond level. If the direct sampling receiving method is adopted, the number of sampling points in the range direction will reach several million or more. Such a large amount of data poses high requirements for data transmission rate and processing speed, resulting in an increase in system complexity. On the other hand, considering that FMCW SAR is generally used as a miniaturized SAR application and its range mapping bandwidth is usually narrow, it is appropriate to adopt the Dechirp receiving method. At this time, the system sampling frequency only needs to be greater than the bandwidth of the beat frequency signal corresponding to the scene mapping bandwidth, so the sampling rate can be greatly reduced, the number of sampling points is reduced, the system equipment is simplified, and it is more suitable for commercial applications.

[0058] The Frequency Scaling Algorithm (FSA) is aimed at the Dechirp received data under the FMCW radar system, and it directly processes the signal after dechirping. FSA performs a variable scale operation on the range fast time in the range-Doppler domain to correct the spatial variation of range migration. First, the range migration of all scatter points in the scene is corrected to that at the reference range, and then a unified reference function is used to correct the remaining range migration. The entire algorithm only includes complex multiplication and FFT operations. Due to its high accuracy and small amount of computation, it has been widely used in Dechirp data processing. Therefore, this application intends to use the frequency scaling algorithm for imaging processing.

[0059] Secondly, the application environment related to the embodiments of the present invention will be described.

[0060] Figure 1 It is a schematic diagram of an application scenario of an embodiment of this application, as Figure 1 shown. This application scenario includes a first microwave radar 1 and a second microwave radar 2, and the detection target is the vehicle in the figure.

[0061] The first microwave radar 1 and the second microwave radar 2 can be any one or a combination of millimeter-wave radars, X-band radars, C-band radars, etc. divided by frequency bands. The first microwave radar 1 and the second microwave radar 2 can be of the same type of radar or different types of radars.

[0062] Specifically, the millimeter-wave radar can be a millimeter-wave radar in bands such as 24 GHz, 77 GHz, 79 GHz, 94 GHz, etc. The first microwave radar 1 and the second microwave radar 2 can also be any one or a combination of millimeter-wave radars with different bands, or millimeter-wave radars with the same band.

[0063] The distributed microwave radar imaging method of the embodiments of this application can be applied to roadside detection systems, driverless systems, or driver assistance warning systems, etc. The roadside detection system can be used for roadside perception. Roadside perception is the basis for data acquisition in intelligent transportation systems and other technologies, providing a basis for highway toll inspection and urban road monitoring. The required data includes: the length, height, number of axles, speed and spacing of vehicle targets, the congestion status of surrounding roads, etc. The driver assistance warning system includes: automatic parking, lane change assistance, blind spot detection, etc.

[0064] For the roadside detection system, the detection target can be a vehicle passing through the roadside detection system, including cars, trucks, freight cars, etc. For the assisted driving system, the detection target can be any target such as vehicles, people, trees, curbs, obstacles, etc.

[0065] Figure 2 FIG. Figure 2 is a schematic structural diagram of a microwave radar imaging system provided by an embodiment of the present application, including a first microwave radar 1, a second microwave radar 2, and a distributed microwave radar imaging device 3. The distributed microwave radar imaging device 3 is respectively connected to the first microwave radar 1 and the second microwave radar 2.

[0066] The distributed microwave radar imaging device 3 processes the radar echo data through the distributed microwave radar imaging method of the embodiment of the present application, thereby imaging the detection target to determine target information, which reflects the shape and size information, speed, position, etc. of the detection target. The distributed microwave radar imaging method of the embodiment of the present application can improve the imaging resolution of the detection target, and its specific implementation manner can be referred to the explanation of the following embodiments.

[0067] The distributed microwave radar imaging device 3 may include: an IO interface 111, a processor 112, and a memory 113 for storing instructions executable by the processor.

[0068] The IO interface 111 may include an input / output (I / O) interface. For example, the output device may be a liquid crystal display (LCD), a light emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector, etc. The input device may be a mouse, a keyboard, a touch screen device or a sensing device, and at least two imaging sensors, etc.

[0069] The processor 112 may be any conventional processor, such as a commercially available central processing unit (CPU). Alternatively, the processor may be a special device such as an application specific integrated circuits (ASIC) or other hardware-based processors. Although Figure 2The functional diagram shows a processor and a memory. However, those of ordinary skill in the art should understand that the processor, radar imaging device, or memory may actually include multiple processors, radar imaging devices, or memories that may or may not be stored within the same physical enclosure. For example, the memory may be a hard disk drive or other storage medium located within an enclosure different from that of the distributed microwave radar imaging device 3. Thus, a reference to a processor or radar imaging device will be understood to include a reference to a collection of processors or computers or memories that may or may not operate in parallel. Different from using a single processor to execute the steps described herein, some components such as the steering component and the deceleration component may each have their own processor, which only performs calculations related to component-specific functions.

[0070] In various aspects described herein, the processor may be located remotely from the microwave radar and communicate wirelessly with the microwave radar. In other aspects, some of the processes described herein are executed on a processor disposed within a roadside base station or a vehicle while others are executed by a remote processor, including taking the necessary steps to perform a single maneuver.

[0071] In some embodiments, the memory 113 may contain instructions 114 (e.g., program logic), which may be executed by the processor 112 to perform various functions of the distributed microwave radar imaging device 3, including those described above. The memory 113 may also contain additional instructions, including instructions for one or more of the first microwave radar 1 or the second microwave radar 2 to send data, receive data from, interact with, and / or control them.

[0072] In addition to the instructions 114, the memory 113 may also store data, such as images of detected targets, or in on-vehicle mode, may store road maps, route information, the position, direction, speed of the vehicle, and other such vehicle data, as well as other information. Such information may be used by the vehicle and the computer system during operation of the vehicle in autonomous, semi-autonomous, and / or manual modes.

[0073] It should be noted that the above-mentioned distributed microwave radar imaging device 3, the first microwave radar 1, and the second microwave radar 2 can be arranged on the same device, such as a roadside sensing base station, a vehicle, etc. In another implementation manner, the first microwave radar 1 and the second microwave radar 2 can be arranged on different devices, such as different roadside sensing base stations, etc. The distributed microwave radar imaging device 3 can be a terminal device, and this imaging device can communicate with the devices where the first microwave radar 1 and the second microwave radar 2 are arranged to obtain radar echo data. For example, the roadside sensing base station transmits the echo data of the first microwave radar 1 and the second microwave radar 2, or the processed radar image or target feature and other detection information to the toll collection and detection system to implement the functions of toll collection inspection and urban road monitoring in the high-speed scenario.

[0074] Among them, the terminal device can be a fixed terminal or a mobile terminal. The fixed terminal can be an industrial computer, etc. The mobile terminal can also be referred to as a user equipment, access terminal, user unit, user station, mobile station, mobile platform, user terminal, terminal, wireless communication device, user agent or user device. The mobile terminal can be an in-vehicle device, a wearable device, a smart phone, a tablet computer, a personal digital processing device, a handheld device with wireless communication function, or other processing devices connected to a wireless modem, etc.

[0075] The terminal device can also be replaced by the control unit of the roadside base station or the vehicle control unit. The radar imaging device in this embodiment can be implemented in software and / or hardware. For example, this device can be the above-mentioned terminal device or the internal chip of the terminal device. Hereinafter, the radar imaging method will be described with the distributed microwave radar imaging device as the execution subject. As Figure 3 shown, this method can include the following steps:

[0076] When the detection target enters the radar beam detection range, the distributed microwave radar imaging device 3 controls the first microwave radar 1 and the second microwave radar 2 to start radar observation on the detection target until the detection target leaves the radar beam.

[0077] The first microwave radar 1 includes a first transmitter, and this first transmitter can be an antenna. The distributed microwave radar imaging device 3 controls the antenna to emit a first detection electromagnetic wave to the detection target. After passing through the detection target, the first detection electromagnetic wave is reflected, and the antenna of the first microwave radar 1 receives the returned electromagnetic wave, that is, the first echo signal.

[0078] The second microwave radar 2 includes a second transmitter, and this second transmitter can be an antenna. The distributed microwave radar imaging device 3 controls the antenna to emit a second detection electromagnetic wave to the detection target. After passing through the detection target, the second detection electromagnetic wave is reflected, and the antenna of the second microwave radar 2 receives the returned electromagnetic wave, that is, the second echo signal.

[0079] Among them, various types of electromagnetic wave signals can be selected for the first detected electromagnetic wave and the second detected electromagnetic wave. Preferably, the first detected electromagnetic wave emitted by the first microwave radar 1 can be a frequency-modulated continuous wave (FMCW) signal. Let the carrier frequency signal be exp(j2πf c t), and the pulse signal is emitted sequentially with a repetition period T. The emission time t m = mT (m = 0, 1, 2......) is called the slow time; the time starting from the emission time is represented by and is called the fast time. The fast time is used to measure the propagation time of the radio wave, while the slow time is used to measure the emission time of the pulse. The relationship between these two times and the total time is: Therefore, the first detected electromagnetic wave has the following mathematical expression 1:

[0080]

[0081] Among them, f c is the center frequency, T p is the pulse width, γ is the frequency modulation rate, t is the total time, is the fast time, and t m is the slow time.

[0082] The first detected electromagnetic wave emitted by the first microwave radar 1 passes through the detected target and is reflected to form a first echo signal. The receiving antenna of the first microwave radar 1 transmits the received first echo signal to the radar receiver. Among them, the distance from the sampling point on the detected target to the first microwave radar 1 is The first echo signal received by the first microwave radar 1 has the following mathematical expression 2:

[0083]

[0084] Among them, A is a constant, C is the speed of light, and the meanings of other parameters are the same as those in expression 1. Preferably, the second detected electromagnetic wave emitted by the second microwave radar 2 can be the same as the first detected electromagnetic wave emitted by the first microwave radar. The specific mathematical expression is the same as expression 1, and the mathematical expression of the second echo signal is the same as expression 2.

[0085] Step 101a: Obtain the first echo signal received by the first microwave radar, and the first microwave radar is set at a first height;

[0086] Step 101b: Obtain the second echo signal received by the second microwave radar, and the second microwave radar is set at a second height, where the first height is lower than the second height.

[0087] The first echo signal is a reflected signal obtained by detecting the detection target with the first detection electromagnetic wave emitted by the first microwave radar 1. The first microwave radar 1 sends the obtained first echo signal to the distributed microwave radar imaging device 3 of this embodiment.

[0088] As described above Figure 1 As shown, the first height refers to the height at which the first microwave radar 1 is set. Specifically, the first microwave radar 1 can be set at a lower position to obtain low-angle data, so that the upper imaging part of the detection target will not be aliased. For example, for the first microwave radar 1 set on the roadside perception base station, it can be set at a height equivalent to the bottom position of the vehicle; for the first microwave radar 1 set on the vehicle, it can be set at the lower part or the bottom of the vehicle body.

[0089] The second echo signal is a reflected signal obtained by detecting the detection target with the second detection electromagnetic wave emitted by the second microwave radar 2. The second microwave radar 2 sends the obtained second microwave signal to the distributed microwave radar imaging device 3 of this embodiment.

[0090] As described above Figure 1 As shown, the second height refers to the height at which the second microwave radar 2 is set. Specifically, the second microwave radar 2 can be set at a higher position to obtain high-angle data, so that the lower imaging part of the detection target will not be aliased. For example, for the second microwave radar 2 set on the roadside perception base station, it can be set at a height equivalent to the top position of the vehicle; for the second microwave radar 2 set on the vehicle, it can be set at the upper part or the top of the vehicle body.

[0091] Among them, the first height is lower than the second height, that is, the installation position of the first microwave radar 1 is lower than that of the second microwave radar 2. The first height being lower than the second height only limits the height dimension direction of the first microwave radar 1 and the second microwave radar 2, and does not limit the coordinate positions of the first microwave radar 1 and the second microwave radar 2 in the horizontal plane. Their coordinates in the horizontal plane can be the same or different.

[0092] Among them, 101a and 101b can be in any order.

[0093] Step 102a: Determine the first radar imaging result image of the detection target based on the first echo signal.

[0094] Step 102b: Determine the second radar imaging result image of the detection target based on the second echo signal.

[0095] After the distributed microwave radar imaging device 3 receives the first echo signal and the second echo signal, radar imaging processing is respectively performed on the echo data of the microwave radars with different perspectives to obtain the imaging result images of each microwave radar, that is, the first radar imaging result image and the second radar imaging result image.

[0096] Among them, 102a and 102b may be in any order.

[0097] Step 103: Fuse the first radar imaging result image and the second radar imaging result image to obtain a target fused image.

[0098] The first radar imaging result image and the second radar imaging result image with different high and low perspectives are placed in the same coordinate system, and optimal extraction and complementary fusion processing are performed on the two images. Finally, the two images are fused to obtain a fused image, that is, the target fused image. The target fused image can obtain more refined resolution and more accurate and complete target feature information.

[0099] Specifically, the first radar imaging result image and the second radar imaging result image can be centrally registered, and the optimal threshold is selected for the two-dimensional image. This threshold is used as the reference line for resolution segmentation and interception. The target is selected in the imaging area with higher resolution for optimal interception and fusion processing, so that the lower boundary of the upper imaging area of the detection target and the upper boundary of the lower imaging area correspond to the reference line of the detection target. The reference line can be selected as the center line.

[0100] Among them, the optimal threshold can be set in advance, and the specific preset value can be set by those skilled in the art according to experience or determined by the specific effect of radar imaging. The present application does not specifically limit the specific value and detailed setting method of the selection of the optimal threshold.

[0101] Step 104: Determine the shape information or structural information of the detection target based on the target fused image.

[0102] After the distributed microwave radar imaging device 3 obtains the target fused image, it determines the shape information or structural information of the detection target. The shape size information of the detection target includes two-dimensional size information including length and height information, and three-dimensional size information including length, height, and width information. Furthermore, the structural information of the detection target can also be obtained. For example, when the detection target is a vehicle, the information of the wheels and axles can be obtained.

[0103] In the embodiment of the present application, since distributed microwave radar imaging realizes the complementary characteristics of high and low perspectives, it can not only measure the length information of the detection target, but also solve the problem of inconsistent resolution in the height dimension of the detection target, realizing high-resolution imaging of the overall detection target. Moreover, due to the fusion of the high and low radar imaging results and the cropping of the partial images with echo aliasing problems, the imaging blind area of a single radar is eliminated.

[0104] Further, Figure 4 As shown in the schematic diagram of the method for determining the first radar imaging result based on the first echo signal in the embodiment of the present application, the method includes:

[0105] Step 201a: Determine the first initial radar imaging image of the detection target based on the first echo signal.

[0106] Among them, multiple algorithms can be used to determine the first initial radar imaging image. Preferably, the frequency scaling algorithm (FSA) is selected. In the embodiment of the present application, based on frequency scaling (FSA) radar imaging processing, the radar data from different perspectives are respectively subjected to radar imaging processing to obtain the initial radar imaging image corresponding to each microwave radar.

[0107] After the distributed microwave radar imaging device 3 receives the first echo signal, it needs to perform dechirp processing in signal processing to reduce the AD sampling rate.

[0108] Dechirp uses an LFM signal with a fixed time, the same frequency and chirp rate as the reference signal, and performs difference frequency processing on the reference signal and the first echo signal. Let the reference distance be R ref , then the mathematical expression 3 of the reference signal is:

[0109]

[0110] Among them, R ref is the reference distance, and the physical meanings of the other letters in expression 3 are the same as those in expressions 1-2, which will not be elaborated here.

[0111] The mathematical expression 4 of dechirp pulse compression is:

[0112]

[0113] [[ID=3S]] is the first echo signal, is the conjugate of the reference signal.

[0114] Through expressions 2-4, the difference frequency output after dechirp processing is obtained, and the expression 5 of the echo after target difference frequency processing is as follows:

[0115]

[0116] Among them, A is the amplitude constant, γ is the frequency modulation rate, and T p is the pulse width, and R ref is the reference distance, is the instantaneous distance between the detected target and the microwave radar, C is the speed of light, and λ is the wavelength of the microwave radar. is the fast-time distance, and its value range is T p is the pulse width, and the slow time t m has a value range of -T a / 2 ≤ t m ≤ T a / 2, and T a is the time for the target to pass through the radar beam.

[0117] The FSA algorithm performs a scale transformation on the fast-time distance scale in the range-Doppler domain to correct the spatial variability of range migration. After being processed by this FSA algorithm, range migration correction can be completed. Radar imaging processing includes range processing and azimuth processing. After completing the range operation, subsequent azimuth processing is carried out. In the azimuth direction, conventional azimuth pulse compression processing is performed.

[0118] Finally, the first initial radar imaging result of the detected target is Expression 6:

[0119]

[0120] In Expression 6, 1 / β is the scale factor of range migration, Δf a is the Doppler bandwidth in the azimuth direction, R B is the scene center, and the meanings of other parameters are the same as those in the foregoing formulas and will not be elaborated here.

[0121] The first initial radar imaging result is shown in Figure 5. In Figure 5, the detected target is a vehicle. Specifically, Figure 5a is the schematic diagram of the actual size of the vehicle, Figure 5b is the schematic diagram of the first initial radar imaging result, Figure 5c is the schematic diagram of the second initial radar imaging result.

[0122] By comparing Figure 5a -c three figures, it is found that the initial imaging result of the vehicle is nonlinearly compressed. The upper part of Figure b has an excessive magnification ratio, and the lower part has a too small compression ratio. In addition, there is aliasing at the bottom of the wheels; the lower part of Figure c has an excessive magnification ratio, and the upper part has a too small compression ratio. Therefore, it can be seen that the first initial radar imaging result has both geometric deformation compression and aliasing characteristics, and the first initial microwave radar imaging image needs to be corrected.

[0123] Step 202a: Perform first geometric deformation correction on the initial first microwave radar imaging image to obtain a first radar imaging result image.

[0124] As described above, the present embodiment adopts synthetic aperture radar technology, and one of the characteristics of synthetic aperture radar images is the phenomenon of shortened uphill distance. The phenomenon of shortened uphill distance occurs because the position of the side-looking radar imaging diagram along the range direction is determined by the slant range of each resolution unit of the target from the radar. According to this rule, when projecting a three-dimensional area into a two-dimensional image, the phenomenon of shortened uphill distance will inevitably occur.

[0125] As Figure 6 shown, the height of the first microwave radar is AB. The radar irradiates the detection target, such as a vehicle, etc. The effective coverage range angle in the range direction is a, and the height of the detection target to be observed is CE. Among them, D and A are at the same horizontal height, and point F is symmetric to point E with respect to point D, and AB = DE = DF.

[0126] The first microwave radar antenna radiates broadband electromagnetic waves to the detection target to be observed. The electromagnetic waves are radiated to the side of the detection target and reflected back to be received by the first microwave radar receiver. The radar echo reflected by the detection target component closer to the radar is received by the receiver first, that is, the echo of point D of the detection target is received by the receiver first, followed by the echoes of points E and F, and finally the echo of point C. Among them, the echoes of points F and E are the same and enter the receiver at the same time. The echoes of the two are indistinguishable in the time dimension, while the SAR imaging range dimension information is distinguished according to the time of arrival at the radar receiver.

[0127] According to the imaging characteristics of the SAR radar, the imaging result of the detection target is projected in the beam direction, and the final imaging width is projected on AC. The final imaging width of the detection target with a height of CE is CD'. Among them, the imaging information of DE and DF is aliased in the D'F area of the imaging width. In this embodiment, according to Figure 6 the geometric relationship of each parameter in, the horizontal distance between the detection target and the first microwave radar is detected, and the horizontal distance is used as the reference line for slant range projection. Combining the height information of the first microwave radar, geometric inversion parameter calculation is performed on the imaging result obtained by the first microwave radar to obtain the actual height of each sampling point on the detection target, so as to perform correction.

[0128] Among them, the imaging width of the detection target is defined as the width information of the height information of the detection target in the first radar imaging result image in the imaging of the detection target by the first microwave radar.

[0129] Step 201b: Determine the second initial radar imaging image of the detection target based on the second echo signal;

[0130] Step 202b: Perform a second geometric deformation correction on the second initial radar imaging image to obtain a second radar imaging result image.

[0131] The processing methods of steps 201b and 202b are the same as those of steps 201a and 202a, and will not be elaborated here.

[0132] The first radar imaging result and the second radar imaging result image are as Figure 7a and 7b shown.

[0133] In this implementation, by performing geometric deformation correction on the preliminary radar imaging image, the influence brought by the inherent slope foreshortening phenomenon in the side-looking perception imaging process is eliminated. The slope foreshortening phenomenon causes geometric deformation distortion of the initial radar imaging image, and the imaging resolution of the detection target is improved through geometric deformation correction.

[0134] Furthermore, the first geometric deformation correction and the second geometric deformation correction include slant range projection, that is, projecting the size length of the detection target in the radar line-of-sight direction onto the actual height of the target. The specific method of the first geometric deformation correction is basically the same as that of the second geometric deformation correction.

[0135] Figure 8 For the schematic diagram of the specific method of the first geometric deformation correction in the embodiment of the present application, taking the first geometric correction as an example on the basis of the above embodiment, as Figure 8 shown, the method may include the following steps:

[0136] Step 301a: Based on the height of the first microwave radar and the shortest distance between the first microwave radar and the detection target, determine the first variation relationship between the first imaging width and the height of the detection target, and the first variation relationship is a non-linear functional relationship.

[0137] The geometric parameters required in this embodiment may include: the height of the first microwave radar and the shortest distance between the first microwave radar and the detection target.

[0138] The height of the first microwave radar can record the radar installation height when deploying the first microwave radar. As Figure 6 shown, the first microwave radar is deployed at the position of point A, and point B is the ground. It can be known that the height of the first microwave radar is AB.

[0139] The shortest distance between the first microwave radar and the detection target. The distributed microwave radar imaging device 3 can detect the nearest wave gate of the detection target through Hough transform as the shortest distance between the first microwave radar and the detection target. As Figure 6 shown, the position where the detection target is located is CE, and the shortest distance between the first microwave radar and the detection target is AD.

[0140] The calculation of geometric inversion parameters in this embodiment refers to obtaining the relationship between the width and height of the radar imaging of the detection target from the initial radar image, so that slant range projection can be performed.

[0141] As Figure 6 shown, taking the above-mentioned shortest distance AD as the slant range projection reference line AD', the geometric inversion parameter calculation is performed on the imaging result obtained by the first microwave radar.

[0142] For the side azimuth imaging of the first microwave radar, according to the Figure 6 SAR imaging geometric relationship in, the geometric inversion parameter calculation relationship is obtained:

[0143]

[0144] Among them, W s is the imaging width of the detection target in the radar image, and this imaging width L D’C is the distance L from the first microwave radar to the vertex of the detection target AC minus the shortest distance L AD .

[0145] The height of the detection target is CE, which is compressed into the length of the imaging width D'C in the radar imaging result. It should be noted that the original detection target DE segment and FD segment are aliased during the imaging process, and the aliasing is in the D'F' segment of the final imaging width.

[0146] Using formula 7, the first variation relationship between the imaging width W s of the detection target and the height H CE of the detection target is formula 8,

[0147]

[0148] Among them, x represents the height of the sampling point of the detection target, F(x) represents the imaging width W s corresponding to the sampling point of the detection target, x0 represents the height H AB of the first microwave radar, and y0 represents the shortest distance L AD between the detection target and the first microwave radar.

[0149] Step 301b: Perform interpolation processing based on the first variation relationship to determine the first radar imaging result image.

[0150] Figure 9 The first variation curve graph of the imaging width and height of the detection target drawn according to the first variation relationship is given. According to the variation curve graph of the imaging width and height of the detection target, the initial imaging result of the first microwave radar is subjected to projection interpolation processing to obtain the result after geometric deformation correction.

[0151] The specific method for the second geometric deformation correction is the same as that for the first geometric deformation correction, and will not be elaborated here. However, since the second microwave radar is set at a relatively high position, as Figure 10 shown, the positional relationship between it and the detection target determines that the second imaging width of the detection target is the distance from the second microwave radar to the bottom point of the detection target minus the shortest distance.

[0152] Similar to the derivation process of formula 8, the second change relationship between the imaging width of the detection target and the height of the detection target is formula 9,

[0153]

[0154] where x represents the height of the sampling point of the detection target, F(x) represents the imaging width W corresponding to the sampling point of the detection target s , x0 represents the height H of the second microwave radar AB , y0 represents the shortest distance L between the detection target and the second microwave radar AD .

[0155] In this implementation, through slant range projection, that is, projecting the size length of the detection target in the radar line-of-sight direction onto the actual height of the target. Since the target is non-linearly compressed in the radar line-of-sight direction, correction processing is required to obtain the actual height of the target. Traditional slant range projection uses a linear stretching scheme. Because its radar is installed on a satellite or an aircraft and the operating distance is far, the ratio of the width of the observed target to the operating distance between the radar is very small, and the non-linear transformation in the slant range projection can be ignored, and approximate linear stretching processing can be used; while in this scheme, the ratio between the height of the observed target and the radar operating distance is not small, and the non-linear transformation in the slant range projection cannot be ignored. Therefore, this implementation is more accurate than the traditional stretching scheme, can more accurately describe the slant range projection result of the target, and thus improves the imaging resolution.

[0156] Furthermore, after the distributed microwave radar imaging device 3 obtains the target fusion image, it can further determine the shape information and structure information of the detection target. As Figure 11 shown, the shape size information of the detection target includes two-dimensional length and height information, or three-dimensional length, height, and width information. The structure information of the detection target can be any conventional structure of the detection target, including the specific quantity and size of wheels, axles, etc.

[0157] Based on the above embodiments, the method includes:

[0158] For two-dimensional dimension information, perform interval equalization processing on the two dimensions of the two spliced and fused images, that is, taking the sampling unit Deltr_R of the side-looking target height dimension as the benchmark, and interpolating or compressing the sampling unit Deltr_A of the length dimension (azimuth direction) into a unified sampling interval. The specific interpolation or compression multiple Deltr_times is calculated as follows:

[0159]

[0160] Wherein: the sampling units of the height dimension and the length dimension (azimuth direction) are as follows respectively:

[0161]

[0162]

[0163] Wherein, C is the speed of light, B is the radar emission bandwidth, and PRF is the radar sampling frequency.

[0164] The above operation obtains the result that the sampling units of the target height and length dimensions are equal. Further, by multiplying the number of scattering points by the sampling unit width, the length and height information of the observed target are obtained.

[0165] Figure 12 The geometric schematic diagram for detecting the three-dimensional dimension information of the target is as shown in Figure 12 As shown, AB is the schematic diagram of the first microwave radar, the detection target is a vehicle, the right-side figure HCJE is the schematic diagram of the vehicle, and the dotted part is the position where the vehicle window is located. The first microwave radar first irradiates the detection target, such as the left-side scattering area of the vehicle, and transmits through the vehicle window to the other side of the vehicle. The top of the other side of the vehicle forms an L-shaped corner reflection characteristic, resulting in a strong scattering characteristic. As shown in the previous embodiment, the height inversion of the CE segment on the left side of the vehicle has been completed. Subsequently, in order to further invert the width information of the vehicle target. The specific inversion is as follows: The first microwave radar detects the information of point J at the top of the other side of the vehicle. We know the lengths of AJ, JI, and AD. Now, we need to solve for the length of DI, which can be solved according to the right triangle AIJ:

[0166] (AI) 2 +(JI) 2 =(AJ) 2

[0167] AI = AD + Bus width

[0168] JI = Bus hight -AB

[0169] (AD + Bus width ) 2 +(Bus hight -AB)2 =(AJ) 2

[0170] Through the above substitution and solution, the width DI of the vehicle target can be obtained.

[0171] Based on the information of the height of point J and the width DI relative to the left side surface of the vehicle obtained above, a three-dimensional stereoscopic imaging result of the target vehicle can be constructed.

[0172] Moreover, the radar imaging method of the embodiments of the present application can image the detection targets in the surrounding environment and accurately provide the size, structure, speed, and position information of the detection targets. So as to perform corresponding operations subsequently. For example, the roadside imaging device can charge the passing vehicles according to the size and structure of the detection targets, and the in-vehicle imaging device can perform assisted driving operations on the vehicle.

[0173] It can be understood that the methods or steps in the above various embodiments can be implemented by a radar imaging device or a chip inside the radar imaging device.

[0174] Figure 13 is a schematic structural diagram of a distributed microwave radar imaging device according to an embodiment of the present application. As Figure 13 shown, the distributed microwave radar imaging device of the present application may include: a first acquisition unit 401 that acquires a first echo signal received by a first microwave radar, where the first microwave radar is disposed at a first height; a second acquisition unit 402 that acquires a second echo signal received by a second microwave radar, where the second microwave radar is disposed at a second height, and wherein the first height is lower than the second height; a first imaging unit 403 that determines a first radar imaging result image of a detection target based on the first echo signal; a second imaging unit 404 that determines a second radar imaging result image of the detection target based on the second echo signal; and a target fusion unit 405 that fuses the first radar imaging result image and the second radar imaging result image to obtain a target fusion image.

[0175] In some embodiments, the first imaging unit 403 is specifically configured to: determine a first initial radar imaging image of the detection target based on the first echo signal; perform a first geometric deformation correction on the first initial radar imaging image to obtain a first radar imaging result image; the second imaging unit 404 is specifically configured to: determine a second initial radar imaging image of the detection target based on the second echo signal; perform a second geometric deformation correction on the second initial radar imaging image to obtain a second radar imaging result image.

[0176] In some embodiments, the first geometric deformation correction includes: determining a first variation relationship between the first imaging width and the height of the detection target based on the height of the first microwave radar and the shortest distance between the first microwave radar and the detection target, where the first variation relationship is a non-linear functional relationship; performing interpolation processing based on the first variation relationship to determine the first radar imaging result image; where the first imaging width of the detection target is the distance from the first microwave radar to the vertex of the detection target minus the shortest distance; the second geometric deformation correction includes: determining a second variation relationship between the imaging width and the height of the detection target based on the height of the second microwave radar and the shortest distance between the second microwave radar and the detection target, where the second variation relationship is a non-linear functional relationship; performing interpolation processing based on the second variation relationship to determine the second radar imaging result image; where the second imaging width of the detection target is the distance from the second microwave radar to the bottom point of the detection target minus the shortest distance.

[0177] In some embodiments, the target fusion unit 405 is specifically configured to: splice and fuse the upper part imaging area corresponding to the detection target in the first radar imaging correction image and the lower part imaging area corresponding to the detection target in the second imaging correction image to obtain a target fusion image. The lower boundary of the upper part imaging area and the upper boundary of the lower part imaging area correspond to the reference line of the detection target.

[0178] In some embodiments, the distributed microwave radar imaging device further includes a target shape determination unit 406, which is specifically configured to: determine the shape information of the detection target based on the target fusion image. The shape information includes the two-dimensional size or three-dimensional size of the detection target.

[0179] The distributed microwave radar imaging device described above in this embodiment can be used to implement the technical solutions of the above method embodiments. The implementation principles and technical effects are similar. The functions of each module can refer to the corresponding descriptions in the method embodiments and will not be elaborated here.

[0180] The embodiment of the present application further provides a distributed microwave radar imaging system, including a first microwave radar 1, a second microwave radar 2, and a distributed microwave radar imaging device 3.

[0181] The distributed microwave radar imaging system of this embodiment can be used to implement the technical solutions of the above method embodiments. The implementation principles and technical effects are similar. The functions of each device can refer to the corresponding descriptions in the method embodiments and will not be elaborated here.

[0182] This embodiment also provides a roadside microwave radar imaging system, which includes a first microwave radar 1, a second microwave radar 2, and a distributed microwave radar imaging device 3. The first microwave radar 1 and the second microwave radar 2 are arranged on the roadside, and the detection target is a vehicle.

[0183] The roadside microwave radar imaging system of this embodiment can be used to implement the technical solutions of the above method embodiments. The implementation principles and technical effects are similar. The functions of each device can refer to the corresponding descriptions in the method embodiments and will not be elaborated here.

[0184] This embodiment also provides a vehicle, which includes a first microwave radar 1, a second microwave radar 2, and a distributed microwave radar imaging device 3. The first microwave radar 1 and the second microwave radar 2 are arranged on the vehicle.

[0185] The vehicle of this embodiment can be used to implement the technical solutions of the above method embodiments. The implementation principles and technical effects are similar. The functions of each device can refer to the corresponding descriptions in the method embodiments and will not be elaborated here.

[0186] It should be noted that the division of modules in the embodiments of this application is illustrative, only a logical function division. In actual implementation, there may be other division methods. In the embodiments of this application, each functional module can be integrated into a processing module, or each module can exist physically alone, or two or more modules can be integrated into one module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules.

[0187] If the above integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the methods described in the various embodiments of this application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, ROM, RAM, magnetic disks, or optical discs that can store programs.

[0188] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that the computer can access, or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD), etc.).

[0189] The program instructions can be implemented in the form of software functional units and can be sold or used as independent products. The memory can be any form of computer-readable storage medium. Based on this understanding, all or part of the technical solutions of the present application can be embodied in the form of a software product, including several instructions for causing a computer device, specifically a processor, to execute all or part of the steps of the target detection device in each embodiment of the present application. The foregoing computer-readable storage media include: USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs, etc., which can store programs of various types.

[0190] The electronic device described above in this embodiment can be used to execute the technical solutions of the above method embodiments. The implementation principle and technical effects are similar. The functions of each component can refer to the corresponding descriptions in the embodiments and will not be elaborated here.

[0191] Finally, it should be noted that the above description is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A distributed microwave radar imaging method, characterized in that, The method includes: Obtaining a first echo signal received by a first microwave radar, where the first microwave radar is set at a first height; Obtaining a second echo signal received by a second microwave radar, where the second microwave radar is set at a second height, and wherein the first height is lower than the second height; Determining a first initial radar imaging image of a detection target based on the first echo signal; performing a first geometric deformation correction on the first initial radar imaging image to obtain a first radar imaging result image; Determining a second initial radar imaging image of the detection target based on the second echo signal; performing a second geometric deformation correction on the second initial radar imaging image to obtain a second radar imaging result image; Performing central registration and optimal threshold selection on the first radar imaging result image and the second radar imaging result image to obtain a reference line; Stitching and fusing an upper part imaging region corresponding to the detection target in the first radar imaging result image and a lower part imaging region corresponding to the detection target in the second imaging result image to obtain a target fusion image, where the lower boundary of the upper part imaging region and the upper boundary of the lower part imaging region correspond to the reference line of the detection target; The first geometric deformation correction includes: determining a first variation relationship between the imaging width and height of the detection target based on the height of the first microwave radar and the shortest distance between the first microwave radar and the detection target, where the first variation relationship is a non-linear functional relationship in slant range projection; correcting the first initial radar imaging image based on the first variation relationship to obtain a first radar imaging result; The second geometric deformation correction includes: determining a second variation relationship between the imaging width and height of the detection target based on the height of the second microwave radar and the shortest distance between the second microwave radar and the detection target, where the second variation relationship is a non-linear functional relationship in slant range projection; correcting the second initial radar imaging image based on the second variation relationship to obtain a second radar imaging result.

2. The method according to claim 1, wherein The correcting the first initial radar imaging image based on the first variation relationship to obtain a first radar imaging result includes: performing interpolation processing on the first initial radar imaging image based on the first variation relationship to determine a first radar imaging result image; wherein the first imaging width of the detection target is the distance between the first microwave radar and the vertex of the detection target minus the shortest distance; The correcting the second initial radar imaging image based on the second variation relationship to obtain a second radar imaging result includes: performing interpolation processing on the second initial radar imaging image based on the second variation relationship to determine a second radar imaging result image; wherein the second imaging width of the detection target is the distance between the second microwave radar and the bottom point of the detection target minus the shortest distance.

3. The method according to any one of claims 1-2, characterized in that, After performing the stitching and fusion of the upper part imaging region corresponding to the detection target in the first radar imaging result image and the lower part imaging region corresponding to the detection target in the second imaging result image to obtain the target fusion image, the following steps are further included: Determine the shape information or structural information of the detection target based on the target fusion image.

4. The method according to claim 3, characterized in that, The shape information includes the two-dimensional size or three-dimensional solid size of the detection target.

5. A distributed microwave radar imaging device, characterized in that, The device includes: A first acquisition unit for acquiring a first echo signal received by a first microwave radar, where the first microwave radar is set at a first height; A second acquisition unit for acquiring a second echo signal received by a second microwave radar, where the second microwave radar is set at a second height, and the first height is lower than the second height; A first imaging unit for determining a first initial radar imaging image of the detection target based on the first echo signal; performing a first geometric deformation correction on the first initial radar imaging image to obtain a first radar imaging result image; A second imaging unit for determining a second initial radar imaging image of the detection target based on the second echo signal; performing a second geometric deformation correction on the second initial radar imaging image to obtain a second radar imaging result image; A target fusion unit for performing central registration and optimal threshold selection on the first radar imaging result image and the second radar imaging result image to obtain a reference line; and stitching and fusing the upper part imaging region corresponding to the detection target in the first radar imaging result image and the lower part imaging region corresponding to the detection target in the second imaging result image to obtain a target fusion image, where the lower boundary of the upper part imaging region and the upper boundary of the lower part imaging region correspond to the reference line of the detection target; The first geometric deformation correction includes: determining a first variation relationship between the imaging width and height of the detection target based on the height of the first microwave radar and the shortest distance between the first microwave radar and the detection target, where the first variation relationship is a non-linear functional relationship in the slant range projection; correcting the first initial radar imaging image based on the first variation relationship to obtain a first radar imaging result; The second geometric deformation correction includes: determining a second variation relationship between the imaging width and height of the detection target based on the height of the second microwave radar and the shortest distance between the second microwave radar and the detection target, where the second variation relationship is a non-linear functional relationship in the slant range projection; correcting the second initial radar imaging image based on the second variation relationship to obtain a second radar imaging result.

6. The device according to claim 5, wherein The step of correcting the first initial radar imaging image based on the first variation relationship to obtain a first radar imaging result includes: performing interpolation processing on the first initial radar imaging image based on the first variation relationship to determine a first radar imaging result image; wherein the first imaging width of the detection target is the distance from the first microwave radar to the vertex of the detection target minus the shortest distance; The correction of the second radar imaging initial image based on the second variation relationship to obtain a second radar imaging result includes: performing interpolation processing on the second radar imaging initial image based on the second variation relationship to determine a second radar imaging result image; Wherein, the second imaging width of the detection target is the distance between the second microwave radar and the bottom point of the detection target minus the shortest distance.

7. The device according to any one of claims 5-6, characterized in that It further includes a target shape determination unit, and the target shape determination unit is specifically configured to: Determine the shape information or structural information of the detection target based on the target fusion image.

8. The device according to claim 7, characterized in that, The shape information includes the two-dimensional size or three-dimensional solid size of the detection target.

9. A distributed microwave radar imaging system, characterized in that, It includes a first microwave radar, a second microwave radar, and the device according to any one of claims 5-8.

10. A roadside microwave radar imaging system, characterized in that, It includes a first microwave radar, a second microwave radar, and the device according to any one of claims 5-8, wherein the first microwave radar and the second microwave radar are arranged on the roadside, and the detection target is a vehicle.

11. A vehicle, characterized in that, It includes a first microwave radar, a second microwave radar, and the device according to any one of claims 5-8, wherein the first microwave radar and the second microwave radar are arranged on the vehicle.

12. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, and the computer program is used to execute the imaging method according to any one of claims 1-4 above.

13. An electronic device, characterized in that, The electronic device includes: A processor; A memory for storing executable instructions of the processor; The processor is used to execute the imaging method according to any one of claims 1-4 above.

Images