FMCW radar target detection angle super-resolution method based on multi-frame data combination

Abstract

The invention discloses an FMCW radar target detection angle super-resolution method based on multi-frame data combination, and the method comprises the steps: carrying out the calculation of target distance and speed information, and obtaining the signal allowance, containing target angle information, of each receiving channel; according to the obtained target speed information, compensating the signal margin containing the target angle information of each receiving channel of multiple historical continuous frames to the current frame moment; according to a time sequence, splicing each receiving channel signal margin of current and historical continuous multiple frames; analyzing the spectrum of the spliced data by using a spectrum analysis method; extracting a plurality of peak values of the frequency spectrum, and calculating a target angle. The method can break through the aperture limitation of a traditional radar physical antenna, and achieves the super-resolution of a target detection angle. According to the method, the sampling length of the radar angle measurement data is expanded by combining the continuous multi-frame and multi-receiving channel data of the FMCW radar, the angle resolution of the radar is improved, and the super-resolution effect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of radar target detection, and in particular to an angle super-resolution method for FMCW radar target detection based on multi-frame data combination. Background Art

[0002] Radar is a widely used target detection sensor, which is widely used in the fields of assisted driving, security monitoring, etc. Radar has a long detection distance and is suitable for use in a variety of weather and lighting conditions. Angular resolution is one of the key technical indicators of radar. High angular resolution reflects the radar's ability to distinguish between two targets with the same distance / speed and similar angles. The angular resolution of radar is mainly related to the aperture of the radar. The larger the aperture of the radar, the higher the angular resolution. However, due to the limitations of the installation location of the equipment, manufacturing cost control, etc., when the physical aperture of the radar cannot be expanded, improving the angular resolution of radar target detection is one of the important technical pursuits in the radar field. Summary of the invention

[0003] The purpose of the present invention is to provide a FMCW radar target detection angle super-resolution calculation method without changing the current radar antenna layout and object aperture in order to solve the problems existing in the above-mentioned prior art.

[0004] The technical solution to achieve the purpose of the present invention is: an FMCW radar target detection angle super-resolution method based on multi-frame data combination, comprising the following steps:

[0005] Step 1: The transmitting channel transmits a signal, and each receiving channel receives the reflected signal of the target. After mixing, filtering and sampling the transmitting signal and the receiving signal, a two-dimensional fast Fourier transform is used to calculate the target distance and speed information, and the signal margin containing the target angle information of each receiving channel is obtained;

[0006] Step 2: According to the obtained target speed information, the signal margin containing the target angle information of each receiving channel of the historical continuous multiple frames is compensated to the current frame time;

[0007] Step 3, splicing the signal margins of each receiving channel of the current and historical continuous multiple frames according to the time sequence;

[0008] Step 4, using a spectrum analysis method to analyze the spectrum of the spliced ​​data;

[0009] Step 5: extract multiple peaks of the spectrum and calculate the target angle.

[0010] Furthermore, in step 1, there are one or more transmitting channels and receiving channels.

[0011] Furthermore, in step 1, the transmitting channel and the receiving channel are physical or virtual.

[0012] Furthermore, the signal margin of multiple receiving channels per frame in step 3 is a spatially continuous sampling signal containing target angle information. in represents the sampling signal of the ith channel of the kth frame, N is the number of channels, k is the current frame number, θ is the angle of the target, d i is the distance of the ith channel.

[0013] Furthermore, before the splicing, step 3 further includes: using a data transformation method so that the signal margins of each receiving channel of the continuous multiple frames maintain continuous changes in amplitude and phase;

[0014] The data conversion method is as follows:

[0015]

[0016] In the formula, Represents the sampling signal of the N-1th channel of the k-j+1th frame, represents the sampling signal of the 0th channel of the kjth frame, Represents the sampling signal of the i-th channel in the kj-th frame.

[0017] Furthermore, in step 3, the signals of the consecutive M frames are spliced ​​according to the time sequence, and the signals of the consecutive multiple frames after splicing are recorded as s:

[0018] s={s k [0:N-1],s k-1 [1:N-1],...,s k-M+1 [1:N-1]};

[0019] In the formula, s k [0:N-1] represents the signal from the 0th channel to the N-1th channel in the kth frame, s k-1 [1:N-1] represents the signal from the 1st channel to the N-1th channel in the k-1th frame, s k-M+1 [1:N-1] represents the signals from the 1st channel to the N-1th channel in the k-M+1th frame.

[0020] Compared with the prior art, the present invention has the following significant advantages:

[0021] (1) Used for radar signal processing and target detection and identification, it can improve the radar angular resolution.

[0022] (2) There is no need to change the current radar antenna array layout and physical aperture, and a FMCW radar target detection angle super-resolution calculation method is provided.

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of the angle super-resolution method for FMCW radar target detection based on multi-frame data combination.

[0025] Figure 2 This is a schematic diagram of the radar's detection of the target at the current frame moment.

[0026] Figure 3 This is a schematic diagram of the radar's detection of the target at the previous frame. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] It should be noted that if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] In one embodiment, in combination Figure 1 , provides an FMCW radar target detection angle super-resolution method based on multi-frame data combination, comprising the following steps:

[0030] Step 1: The transmitting channel transmits a signal, and each receiving channel receives the reflected signal of the target. After mixing, filtering and sampling the transmitting signal and the receiving signal, a two-dimensional fast Fourier transform is used to calculate the target distance and speed information, and the signal margin containing the target angle information of each receiving channel is obtained;

[0031] Here, there are one or more transmitting channels and receiving channels.

[0032] Here, the transmitting channel and the receiving channel in step 1 are physical or virtual.

[0033] Here, the phase of the transmitted signal can be expressed as:

[0034]

[0035] Where t is time, f k is the starting frequency of the kth frame, B k is the bandwidth of the kth frame, T k The duration of the rising edge of each chirp.

[0036] Each receiving channel receives the reflected signal of the target, and the phase of the received signal can be expressed as:

[0037]

[0038] in, R(t) is the distance of the target at the current moment, i=0...N-1, N is the number of channels, θ is the angle of the target, d i is the distance of the ith channel, and c is the signal propagation speed, i.e. the speed of light.

[0039] By mixing and filtering the transmitted and received signals, signal data containing target distance, speed and angle information is obtained, and the phase is:

[0040]

[0041] The signals of each receiving channel are processed separately through two-dimensional fast Fourier transform to obtain information such as the distance R and speed v of the target, and the signal margin of each receiving channel containing the target angle information is obtained. The phase of the signal margin is:

[0042]

[0043] Where R k is the distance to the target at the start of the frame.

[0044] Step 2: According to the obtained target speed information, the signal margin containing the target angle information of each receiving channel of the historical continuous multiple frames is compensated to the current frame time;

[0045] Here, phase compensation is performed on the historical signal data. The historical signal data also contains the angle information of the target. Due to the movement of the target, the historical distance of the target is different from the current one, resulting in a difference in the phase of the historical signal data and the current one. The compensation process of the historical signal data compensates the signal margin containing the target angle information of each historical receiving channel to the current frame time based on the obtained speed and other information, so that the target distance R can be filtered out. k The phase difference caused by the change in is used to obtain the signal margin containing only the target angle information.

[0046] Step 3, splicing the signal margins of each receiving channel of the current and historical continuous multiple frames according to the time sequence;

[0047] Step 4, using a spectrum analysis method to analyze the spectrum of the spliced ​​data;

[0048] Here, the spectrum analysis method includes Fourier transform, fast Fourier transform, non-uniform Fourier transform or digital beam forming, etc.

[0049] Step 5: extract multiple peaks of the spectrum and calculate the target angle.

[0050] Further, in one embodiment, the signal margin of the multiple receiving channels in each frame in step 3 is a spatially continuous sampling signal containing target angle information. in represents the sampling signal of the ith channel of the kth frame, N is the number of channels, k is the current frame number, θ is the angle of the target, d i is the distance of the ith channel.

[0051] Furthermore, in one of the embodiments, step 3, before the splicing, further includes: using a data transformation method so that the signal margins of each receiving channel of the consecutive multiple frames maintain continuous changes in amplitude and phase;

[0052] The data conversion method is as follows:

[0053]

[0054] In the formula, Represents the sampling signal of the N-1th channel of the k-j+1th frame, represents the sampling signal of the 0th channel of the kjth frame, Represents the sampling signal of the i-th channel in the kj-th frame.

[0055] Furthermore, in one of the embodiments, in step 3, the signals of the consecutive M frames are spliced ​​according to the time sequence, and the signals of the consecutive multiple frames after splicing are recorded as s:

[0056] s={s k [0:N-1],s k-1 [1:N-1],...,s k-M+1 [1:N-1]};

[0057] In the formula, s k [0:N-1] represents the signal from the 0th channel to the N-1th channel in the kth frame, s k-1 [1:N-1] represents the signal from the 1st channel to the N-1th channel in the k-1th frame, s k-M+1 [1:N-1] represents the signals from the 1st channel to the N-1th channel in the k-M+1th frame.

[0058] In one embodiment, a FMCW radar target detection angle super-resolution system based on multi-frame data combination is provided, the system comprising:

[0059] The first module is used to realize: the transmitting channel transmits a signal, each receiving channel receives the reflected signal of the target, and after mixing, filtering and sampling the transmitting signal and the receiving signal, a two-dimensional fast Fourier transform is used to solve the target distance and speed information, and the signal margin containing the target angle information of each receiving channel is obtained;

[0060] The second module is used to compensate the signal margin containing the target angle information of each receiving channel of the historical continuous multiple frames to the current frame time according to the obtained target speed information;

[0061] The third module is used to splice the signal margins of each receiving channel of the current and historical continuous multiple frames according to the time sequence;

[0062] The fourth module is used to analyze the spectrum of the spliced ​​data using a spectrum analysis method;

[0063] The fifth module is used to extract multiple peaks of the spectrum and calculate the target angle.

[0064] For the specific definition of the FMCW radar target detection angle super-resolution system based on multi-frame data combination, please refer to the definition of the FMCW radar target detection angle super-resolution method based on multi-frame data combination mentioned above, which will not be repeated here. Each module in the above-mentioned FMCW radar target detection angle super-resolution system based on multi-frame data combination can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory in the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0065] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the following is achieved:

[0066] Step 1: The transmitting channel transmits a signal, and each receiving channel receives the reflected signal of the target. After mixing, filtering and sampling the transmitting signal and the receiving signal, a two-dimensional fast Fourier transform is used to calculate the target distance and speed information, and the signal margin containing the target angle information of each receiving channel is obtained;

[0067] Step 2: According to the obtained target speed information, the signal margin containing the target angle information of each receiving channel of the historical continuous multiple frames is compensated to the current frame time;

[0068] Step 3, splicing the signal margins of each receiving channel of the current and historical continuous multiple frames according to the time sequence;

[0069] Step 4, using a spectrum analysis method to analyze the spectrum of the spliced ​​data;

[0070] Step 5: extract multiple peaks of the spectrum and calculate the target angle.

[0071] For the specific limitations of each step, please refer to the limitations of the FMCW radar target detection angle super-resolution method based on multi-frame data combination mentioned above, which will not be repeated here.

[0072] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the computer program implements:

[0073] Step 1: The transmitting channel transmits a signal, and each receiving channel receives the reflected signal of the target. After mixing, filtering and sampling the transmitting signal and the receiving signal, a two-dimensional fast Fourier transform is used to calculate the target distance and speed information, and the signal margin containing the target angle information of each receiving channel is obtained;

[0074] Step 2: According to the obtained target speed information, the signal margin containing the target angle information of each receiving channel of the historical continuous multiple frames is compensated to the current frame time;

[0075] Step 3, splicing the signal margins of each receiving channel of the current and historical continuous multiple frames according to the time sequence;

[0076] Step 4, using a spectrum analysis method to analyze the spectrum of the spliced ​​data;

[0077] Step 5: extract multiple peaks of the spectrum and calculate the target angle.

[0078] For the specific limitations of each step, please refer to the limitations of the FMCW radar target detection angle super-resolution method based on multi-frame data combination mentioned above, which will not be repeated here.

[0079] As a specific example, in one of the embodiments, the present invention is further verified and explained in detail.

[0080] This embodiment takes a one-transmitter-four-receiver FMCW radar as an example. Figure 1 The present invention provides an angle super-resolution method for FMCW radar target detection based on the combination of two consecutive frames of data. The method includes signal transmission and reception, compensation of historical signal data, splicing of consecutive multi-frame multi-channel signals, spectrum calculation, etc.

[0081] Step 1: The FMCW radar transmit channel transmits a frequency modulated continuous wave, and the receiving channel receives the echo signal reflected by the target. The transmission and reception process is as follows: Figure 2 As shown. The phase of the transmitted signal can be expressed as:

[0082]

[0083] Where t is time, f k is the starting frequency of the kth frame, B k is the bandwidth of the kth frame, T k The duration of the rising edge of each chirp.

[0084] Each receiving channel receives the reflected signal of the target, and the phase of the received signal can be expressed as:

[0085]

[0086] in R(t) is the distance of the target at the current moment, i=0...N-1, N is the number of channels, and θ is the angle of the target.

[0087] By mixing and filtering the transmitted and received signals, signal data containing target distance, speed and angle information is obtained, and the phase is:

[0088]

[0089] The signals of each receiving channel are processed separately through two-dimensional fast Fourier transform to obtain information such as the distance R and speed v of the target, and the signal margin of each receiving channel containing the target angle information is obtained. The phase of the signal margin is:

[0090]

[0091] Where R k is the distance to the target at the start of the frame.

[0092] Step 2: Perform phase compensation on the historical signal data. The historical signal data also contains the angle information of the target. Due to the movement of the target, the historical distance of the target is different from the current one, resulting in a difference in the phase of the historical signal data and the current one, such as Figure 3 The compensation process of historical signal data is based on the obtained speed and other information. The signal margin containing the target angle information of each historical receiving channel is compensated to the current frame time, so the target distance R can be filtered out. k The phase difference caused by the change in is used to obtain the signal margin containing only the target angle information. For example, when there is only one target and the angle is θ, the relative phase of the signal margin of each channel is:

[0093]

[0094] After filtering, the signal residue of multiple channels in each frame is a spatial continuous sampling signal containing only the target angle information, which is recorded as Where k is the current frame number, and 0, 1, 2, and 3 are the numbers of the receiving channels.

[0095] Step 3: Splice the signals of the current frame and the previous frame according to the time sequence. In order to make the signal margins of each receiving channel of multiple consecutive frames maintain continuous changes in amplitude and phase, the previous frame signal is transformed as follows before splicing:

[0096]

[0097] The signal of multiple consecutive frames after splicing is recorded as s = {s k [0:3],s k-1 [1:3]}.

[0098] Step 4: The spectrum calculation process uses the digital beamforming method to analyze the spectrum of the spliced ​​signal data. The steering vector used by the beamforming method is:

[0099] sv={sv k [0:3],sv k-1 [1:3]}

[0100] in,

[0101]

[0102]

[0103] θ′=[θ0,θ1,...,θ M ] T

[0104] Where θ′ is the angle used by digital beamforming, and M is the number of angles used by digital beamforming.

[0105] The obtained spectrum information is:

[0106] p(θ′)=sv*s

[0107] By searching for the peak in the spectrum p(θ′), the angle of the target can be obtained.

[0108] Original signal k The number of spatial sampling points is N = 4, and the relative sampling length is The number of sampling points of the spliced ​​signal s is 2N-1=7, and the relative sampling length Therefore, it can be seen that, compared with the original signal, by combining multiple frames of data, the number of sampling points increases, and the sampling length is extended, the radar's target detection can achieve the effect of angle super-resolution.

[0109] In summary, the present invention can break through the physical antenna aperture limitation of traditional radars and achieve super-resolution of target detection angles. This method combines the data of multiple consecutive frames and multiple receiving channels of FMCW radars to expand the sampling length of radar angle measurement data, improve the angular resolution of the radar, and achieve super-resolution effects.

[0110] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A FMCW radar target detection angle super-resolution method based on multi-frame data combination, characterized in that: The following steps are involved: Step 1: The transmitting channel transmits a signal, and each receiving channel receives the reflected signal of the target. After mixing, filtering and sampling the transmitting signal and the receiving signal, a two-dimensional fast Fourier transform is used to calculate the target distance and speed information, and the signal margin containing the target angle information of each receiving channel is obtained; Step 2: According to the obtained target speed information, the signal margin containing the target angle information of each receiving channel of the historical continuous multiple frames is compensated to the current frame time; Step 3, splicing the signal margins of each receiving channel of the current and historical continuous multiple frames according to the time sequence; Step 4, using a spectrum analysis method to analyze the spectrum of the spliced ​​data; Step 5: extract multiple peaks of the spectrum and calculate the target angle.

2. The FMCW radar target detection angle super-resolution method based on multi-frame data combination according to claim 1 is characterized in that: In step 1, there are one or more transmitting channels and receiving channels.

3. The FMCW radar target detection angle super-resolution method based on multi-frame data combination according to claim 1 is characterized in that: In step 1, the transmitting channel and the receiving channel are physical or virtual.

4. The FMCW radar target detection angle super-resolution method based on multi-frame data combination according to claim 1 is characterized in that: The signal margin of multiple receiving channels in each frame in step 3 is a spatial continuous sampling signal containing target angle information. in represents the sampling signal of the ith channel of the kth frame, N is the number of channels, k is the current frame number, θ is the angle of the target, d i is the distance of the ith channel.

5. The FMCW radar target detection angle super-resolution method based on multi-frame data combination according to claim 4 is characterized in that: Step 3, before splicing, also includes: using a data transformation method so that the signal margins of each receiving channel of consecutive multiple frames maintain continuous changes in amplitude and phase; The data conversion method is as follows: In the formula, Represents the sampling signal of the N-1th channel of the k-j+1th frame, represents the sampling signal of the 0th channel of the kjth frame, Represents the sampling signal of the i-th channel in the kj-th frame.

6. The FMCW radar target detection angle super-resolution method based on multi-frame data combination according to claim 5 is characterized in that: In step 3, the signals of M consecutive frames are spliced ​​according to the time sequence, and the signals of the consecutive multiple frames after splicing are recorded as s: s={s k [0:N-1],s k-1 [1:N-1],…,s k-M+1 [1:N-1]}; In the formula, s k [0:N-1] represents the signal from the 0th channel to the N-1th channel of the kth frame, s k-1 [1:N-1] represents the signal from the 1st channel to the N-1th channel in the k-1th frame, s k-M+1 [1:N-1] represents the signals from the 1st channel to the N-1th channel in the k-M+1th frame.

7. The FMCW radar target detection angle super-resolution method based on multi-frame data combination according to claim 1 is characterized in that: The spectrum analysis method in step 4 includes Fourier transform, fast Fourier transform, non-uniform Fourier transform or digital beam forming.

8. The FMCW radar target detection angle super-resolution system based on multi-frame data combination based on the method described in claims 1 to 7 is characterized in that: The system comprises: The first module is used to realize: the transmitting channel transmits a signal, each receiving channel receives the reflected signal of the target, and after mixing, filtering and sampling the transmitting signal and the receiving signal, a two-dimensional fast Fourier transform is used to solve the target distance and speed information, and the signal margin containing the target angle information of each receiving channel is obtained; The second module is used to compensate the signal margin containing the target angle information of each receiving channel of the historical continuous multiple frames to the current frame time according to the obtained target speed information; The third module is used to splice the signal margins of each receiving channel of the current and historical continuous multiple frames according to the time sequence; The fourth module is used to analyze the spectrum of the spliced ​​data using a spectrum analysis method; The fifth module is used to extract multiple peaks of the spectrum and calculate the target angle.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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