CN111537985B - Vehicle-mounted radar target detection method and device - Google Patents
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- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/04—Systems determining presence of a target
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- G—PHYSICS
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- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
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Abstract
The embodiment of the invention provides a vehicle-mounted radar target detection method and a device, wherein the method comprises the steps of firstly using a first constant false alarm rate threshold value to detect each detected unit in a corresponding distance range in a non-coherent overlay map and determine the detected unit with a possible target for a preset long-distance range, namely a specific distance range causing false alarm in a traditional vehicle-mounted radar target detection method; classifying the tested units possibly having the targets by using a classification threshold higher than the first constant false alarm rate threshold to determine real targets and targets to be determined; and finally, the authenticity of the target to be determined is confirmed by utilizing the phase relation between the echo signals received by different antennas, so that the detection capability of the vehicle-mounted radar at a specific angle is improved.
Description
Technical Field
The invention relates to the technical field of vehicle-mounted radars, in particular to a vehicle-mounted radar target detection method and device.
Background
The vehicle-mounted radar has good speed measurement capability on a target, good penetration capability on rain and fog and no influence of illumination intensity, so that the vehicle-mounted radar becomes an irreplaceable sensor choice in an intelligent driving scheme. The target detection is a very important ring in the signal processing flow of the vehicle-mounted radar, if the detection condition is too loose, a higher false alarm rate can be caused, and if the detection condition is too severe, a higher false alarm rate can be caused.
In a conventional vehicle-mounted radar target detection method, echo signals of each receiving antenna in an antenna array are subjected to two-dimensional fourier transform to obtain a Range-Doppler Map (RDM), and then the RDMs of the echo signals received by all the receiving antennas are subjected to Non-coherent Integration (NCI) to obtain an NCI Map. The NCI chart is then examined for Constant False Alarm Rate (CFAR). And if the signal-to-noise ratio of the unit to be detected is higher than the detection threshold, determining that the target exists in the unit, otherwise, determining that the target does not exist in the unit.
According to the traditional vehicle-mounted radar target detection method, the effective detection distance is shorter in the area closer to the radar beam edge. Referring to fig. 1, an angle radar is generally installed on each of the left and right rear sides of an automobile, and the two angle radars need to observe not only a target in an adjacent lane but also a target in the lane. The inventor finds that when the traditional vehicle-mounted radar target detection method is adopted, the target in the lane is located at the edge of a wave beam due to the installation angle of the angle radar, the antenna gain is poor, the effective detection distance in the lane is shortened, and the false alarm is easily caused.
Disclosure of Invention
In view of this, the invention provides a method and an apparatus for detecting a target of a vehicle-mounted radar, which aim to improve the detection capability of the vehicle-mounted radar at a specific angle.
In order to achieve the above object, the following solutions are proposed:
in a first aspect, a vehicle-mounted radar target detection method is provided, including:
acquiring an echo signal received by each receiving antenna in an antenna array, and respectively performing two-dimensional Fourier transform on the echo signal received by each receiving antenna to obtain a range-Doppler diagram of the echo signal received by each receiving antenna;
performing non-coherent superposition on the range-Doppler images of the echo signals received by all the receiving antennas to obtain a non-coherent superposition image;
for each unit to be tested positioned in a preset long-distance range in the non-coherent superposition map, judging whether the signal-to-noise ratio of the unit to be tested is greater than a preset first constant false alarm rate threshold value, if not, determining that the unit to be tested does not have a target, and if so, determining that the unit to be tested possibly has the target;
for the tested unit with a possible target, judging whether the signal-to-noise ratio of the tested unit is greater than a preset classification threshold, wherein the classification threshold is greater than the first constant false alarm rate threshold, if so, determining that the tested unit has the target, and if not, determining that the tested unit has the target to be confirmed;
for each tested unit with a target to be confirmed, acquiring data from a target position in a range-doppler diagram of an echo signal received by each receiving antenna, and introducing phase compensation to the data based on a preset angle, wherein the target position is a position corresponding to the tested unit with the target to be confirmed;
and for each tested unit with the target to be confirmed, judging whether the target exists or not by using the data after the phase compensation is introduced.
Optionally, the determining, by using the data after introducing the phase compensation, whether the target exists in each unit to be tested in which the target to be confirmed exists specifically includes:
for each tested unit with the target to be confirmed, performing coherent superposition on all data with introduced phase compensation to obtain coherent superposition results;
acquiring a non-coherent superposition result corresponding to each tested unit with a target to be confirmed; wherein, the non-coherent superposition result obtaining mode comprises: obtaining a non-coherent superposition result corresponding to each unit to be tested with the target to be confirmed from the non-coherent superposition map, or performing non-coherent superposition on all data before phase compensation is introduced for each unit to be tested with the target to be confirmed to obtain the non-coherent superposition result;
calculating the ratio of the coherent superposition result divided by the non-coherent superposition result;
and judging whether the ratio is larger than a preset ratio threshold value, if so, determining that the target exists in the unit to be tested, and if not, determining that the target does not exist in the unit to be tested.
Optionally, before the step of determining whether the signal-to-noise ratio of the measured unit, which may have the target, is greater than a preset classification threshold, the method further includes:
and for the tested units with adjacent positions and the judgment results of which are possible to have targets, modifying the judgment result of the tested unit with the echo power not being the maximum value into the non-existence target.
Optionally, the vehicle-mounted radar target detection method further includes:
and judging whether the signal-to-noise ratio of each unit to be tested in a preset close distance range in the non-coherent overlay map is greater than a preset second constant false alarm rate threshold value, if so, determining that the target exists in the unit to be tested, and if not, determining that the target does not exist in the unit to be tested.
Optionally, after the step of determining that the target exists in the unit under test, the method further includes:
and for the tested units with adjacent positions and the judgment results of which are targets, modifying the judgment result of the tested unit with the echo power not being the maximum value into the absence of the targets.
In a second aspect, an on-vehicle radar target detection device is provided, including:
the echo signal acquisition unit is used for acquiring echo signals received by each receiving antenna in the antenna array, and respectively carrying out two-dimensional Fourier transform on the echo signals received by each receiving antenna to obtain a range Doppler diagram of the echo signals received by each receiving antenna;
the non-coherent superposition unit is used for carrying out non-coherent superposition on the range-Doppler diagrams of the echo signals received by all the receiving antennas to obtain a non-coherent superposition diagram;
the first judgment unit is used for judging whether the signal-to-noise ratio of each unit to be tested positioned in a preset long-distance range in the non-coherent overlay map is greater than a preset first constant false alarm rate threshold value, if not, the unit to be tested is determined to have no target, and if yes, the unit to be tested is determined to possibly have the target;
a second judging unit, configured to judge, for the tested unit that may have a target, whether a signal-to-noise ratio of the tested unit is greater than a preset classification threshold, where the classification threshold is greater than the first constant false alarm rate threshold, if yes, determine that the tested unit has the target, and if not, determine that the tested unit has the target to be confirmed;
the phase compensation unit is used for acquiring data from a target position in a range-doppler diagram of an echo signal received by each receiving antenna for each tested unit with a target to be confirmed, and introducing phase compensation to the data based on a preset angle, wherein the target position is a position corresponding to the tested unit with the target to be confirmed;
and the third judging unit is used for judging whether the target exists or not by using the data after the phase compensation is introduced for each tested unit with the target to be confirmed.
Optionally, the third determining unit specifically includes:
the superposition subunit is used for carrying out coherent superposition on all the data introduced with the phase compensation for each tested unit with the target to be confirmed to obtain coherent superposition results; acquiring a non-coherent superposition result corresponding to each tested unit with a target to be confirmed; wherein, the non-coherent superposition result obtaining mode comprises: obtaining a non-coherent superposition result corresponding to each unit to be tested with the target to be confirmed from the non-coherent superposition map, or performing non-coherent superposition on all data before phase compensation is introduced for each unit to be tested with the target to be confirmed to obtain the non-coherent superposition result;
the calculating subunit is used for calculating a ratio of the coherent superposition result divided by the non-coherent superposition result;
and the judging subunit is used for judging whether the ratio is greater than a preset ratio threshold, if so, determining that the target exists in the unit to be detected, and if not, determining that the target does not exist in the unit to be detected.
Optionally, the vehicle-mounted radar target detection device further includes:
a first modifying unit, configured to modify, before executing the second determining unit, a determination result of the unit under test, for which positions are adjacent and determination results are all possible targets, to be non-target-present, the determination result of the unit under test, for which echo power is not a maximum value.
Optionally, the vehicle-mounted radar target detection device further includes:
and the fourth judging unit is used for judging whether the signal-to-noise ratio of each detected unit positioned in a preset close distance range in the non-coherent overlay map is greater than a preset second constant false alarm rate threshold value, if so, determining that the detected unit has a target, and if not, determining that the detected unit does not have the target.
Optionally, the vehicle-mounted radar target detection device further includes:
and the second modification unit is used for modifying the judgment result of the tested unit of which the echo power is not the maximum value into the target-free state for the tested units of which the positions are adjacent and the judgment results are both targets.
Compared with the prior art, the technical scheme of the invention has the following advantages:
according to the technical scheme, the method comprises the steps that for a preset long-distance range, namely for a specific distance range causing false alarm in a traditional vehicle-mounted radar target detection method, a first constant false alarm rate threshold value is used for detecting each detected unit in a corresponding distance range in a non-coherent overlay map, and the detected unit with a target possibly existing is determined; classifying the tested units possibly having the targets by using a classification threshold higher than the first constant false alarm rate threshold to determine real targets and targets to be determined; and finally, the authenticity of the target to be determined is confirmed by utilizing the phase relation between the echo signals received by different antennas, so that the detection capability of the vehicle-mounted radar at a specific angle is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic view of an angle radar mounting angle;
fig. 2 is a flowchart of a target detection method for a vehicle-mounted radar according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a vehicle radar antenna array;
FIG. 4 is an intercepted NCI diagram provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram of an embodiment of the present invention providing a target signal-to-noise ratio exceeding a first CFAR threshold;
FIG. 6 is a schematic diagram of an effective target where the signal-to-noise ratio exceeds the classification threshold in the target of FIG. 5 according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a target determined to be a valid target by using phase compensated data according to an embodiment of the present invention;
fig. 8 is a schematic diagram of all effective targets finally detected by the vehicle-mounted radar target detection method according to the embodiment of the present invention;
fig. 9 is a schematic logical structure diagram of a vehicle-mounted radar target detection device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a target detection scheme capable of improving the specific angle detection capability of a vehicle-mounted radar, which comprises the steps of firstly determining an angle expected to improve the detection capability, namely an expected observation angle; and then determining a distance range within which the detection effect can be ensured by the traditional vehicle-mounted radar target detection method at the expected observation angle, and dividing the observation area into a short-distance range and a long-distance range according to the distance range to perform target detection. The short-distance range is a distance range within which the detection effect can be ensured at an expected observation angle by the traditional vehicle-mounted radar target detection method. The long-distance range is a distance range within which the detection effect cannot be guaranteed at an expected observation angle by a traditional vehicle-mounted radar target detection method. The specific determination process of the long-distance range is as follows: knowing a radar installation angle and an expected observation angle, obtaining the allowable maximum detection distance of the radar through analysis, and obtaining the farthest detection distance at the expected observation angle by using a traditional vehicle-mounted radar target detection method; the lower limit of the long-distance range is defined as the farthest detection distance of the traditional vehicle-mounted radar target detection method at the expected observation angle, and the upper limit of the long-distance range is defined as the maximum detection distance allowed by the radar.
The traditional vehicle-mounted radar target detection method can be used for the short distance range, and other vehicle-mounted radar target detection methods with better detection effects can be used. For the long-distance range, detecting each detected unit in the long-distance range in the non-coherent overlay map by using a first constant false alarm rate threshold value, and determining the detected unit with a target possibly existing; classifying the tested units possibly having the targets by using a classification threshold higher than the first constant false alarm rate threshold to determine a real target and a target to be determined; and then, the authenticity of the target to be determined is confirmed by utilizing the phase relation among the echo signals received by different receiving antennas, so that the detection capability of the vehicle-mounted radar at a specific angle is improved.
Fig. 2 provides a vehicle radar target detection method for an embodiment of the present invention, where the method may include the following steps:
s21: and acquiring an echo signal received by each receiving antenna in the antenna array, and respectively performing two-dimensional Fourier transform on the echo signal received by each receiving antenna to obtain the RDM of the echo signal received by each receiving antenna.
As shown in fig. 3, assuming that N receiving antennas are arranged at equal intervals, and the interval between two adjacent receiving antennas is d, the echo signals X received by the N receiving antennas are obtained1、X2、…、XNEach echo signal comprises Na pulses, and each pulse comprises Nr sampling points; arranging the echo signals of each receiving antenna in a dimension of [ Na × Nr]Each row contains a pulse of information. The echo signal of each receiving antenna is respectively subjected to two-dimensional Fourier transform, namely each [ Na multiplied by Nr ]]The two-dimensional time domain data in the matrix of (a) are respectively subjected to two-dimensional fourier transform.
S22: and performing NCI on the RDMs of the echo signals received by all the receiving antennas to obtain an NCI diagram.
The NCI diagram is also essentially a two-dimensional matrix, where each element is referred to as a unit under test. The row and column coordinate positions of the elements in the two-dimensional matrix are referred to as the locations of the cells under test. The specific value of an element in the NCI chart is the echo power of the unit under test.
S23: and judging whether the signal-to-noise ratio of each tested unit located in a preset remote distance range in the NCI diagram is greater than a preset first CFAR threshold, if not, determining that the tested unit does not have a target, and if so, determining that the tested unit possibly has the target.
The signal-to-noise ratio of the unit to be tested refers to the ratio of the echo power and the noise power of the unit to be tested; calculating the signal-to-noise ratio of the unit to be detected is one step of operation in the CFAR detection method, and power statistics is carried out on reference units around the unit to be detected to serve as noise power, and then the signal-to-noise ratio of the unit to be detected is calculated.
An angle desired to improve the detectivity is selected in advance according to the installation angle of the radar in an actual situation, and a phase difference of the angle with respect to the center of the antenna beam is calculated. Taking fig. 1 as an example, the angle β at which the detection capability is expected to be improved may be set to 60 °; assuming that the maximum allowable detection distance of the radar waveform parameter is 100 meters, the near-far distance range is divided according to the radar detection capability and the desired observation angle. If the traditional vehicle-mounted radar target detection mode cannot guarantee the detection effect beyond the expected observation angle of 80 meters, the short-distance range is divided into 0-80 m, and the long-distance range is divided into 80-100 m. Step S23 is executed to detect each unit under test located in the long-distance range in the NCI chart by using the first CFAR threshold, and determine the unit under test where the target may exist. The first CFAR threshold is smaller than a CFAR threshold used in a conventional vehicle-mounted radar target detection method, but the first CFAR threshold is not easily too small, for example, 13dB of the CFAR threshold used in the conventional vehicle-mounted radar target detection method, the first CFAR threshold is set to 9dB, and a specific threshold can be set according to experience or a calibration result.
S24: and for the tested unit with the possible target, judging whether the signal-to-noise ratio of the tested unit is greater than a preset classification threshold, wherein the classification threshold is greater than a first CFAR threshold, if so, determining that the target exists in the tested unit, and if not, determining that the target to be confirmed exists in the tested unit.
The classification threshold may be the same as the CFAR threshold used in the conventional vehicle radar target detection approach. For example, the CFAR threshold value 13dB adopted in the conventional vehicle radar target detection method sets the classification threshold value to 13 dB. Of course, the classification threshold may not be the same as the CFAR threshold used in the conventional vehicle radar target detection method. For example, the classification threshold is set to 12dB, 14dB, and the like, as the CFAR threshold is 13dB used in the conventional vehicle-mounted radar target detection method, and the specific threshold may be set by a calibration result or experience. And classifying the tested units possibly having the targets by using the classification threshold value to determine the real targets and the targets to be determined.
The inventor finds that in a real scene, the echo power of a target may be distributed in a plurality of adjacent units under test, so that the plurality of adjacent units under test are judged as the units under test in which the target may exist after the detection operation. In order to reduce the amount of calculation, the tested unit with the strongest echo power (namely peak value) in the adjacent tested units belonging to the same target is extracted as the representative unit of the target. Therefore, before executing the step, the determination result of the unit under test whose echo power is not the maximum value may be modified to be the target-free unit under test whose positions are adjacent and whose determination results are all targets that may exist.
S25: and for each tested unit with the target to be confirmed, acquiring data from a target position in the RDM of the echo signal received by each receiving antenna, and introducing phase compensation to the data based on a preset angle, wherein the target position is a position corresponding to the tested unit with the target to be confirmed.
The preset angle is the expected observation angle. The desired observation angle is based on the description in the radar coordinate system. If the included angle between the longitudinal coordinate axis of the radar coordinate system of the right-side angle radar and the longitudinal coordinate axis of the vehicle coordinate system in fig. 1 is 140 °, and the included angle between the beam pointing to the lane and the longitudinal coordinate axis of the radar coordinate system is 60 °, it is desirable to improve the detection capability of the angle pointing to the lane, and the expected observation angle may be set to be 60 °. In addition, it should be noted that: in practical application, the preset angles can be multiple, and the division of the long-distance range and the short-distance range corresponding to each preset angle can be determined according to the distance range of the traditional vehicle-mounted radar target detection method, which can ensure the detection effect, at the preset angle. The various thresholds corresponding to different preset angles may be the same or different, and may be determined empirically or by calibration.
S26: and for each tested unit with the target to be confirmed, judging whether the target exists or not by using the data after the phase compensation is introduced.
The authenticity of the target to be determined is confirmed by utilizing the phase relation among the echo signals received by different receiving antennas, so that the detection capability of the vehicle-mounted radar at a specific angle is improved. In a specific implementation manner of the embodiment of the present invention, for each unit under test having a target to be confirmed, determining whether the target exists by using data obtained after introducing phase compensation includes: for each tested unit with the target to be confirmed, performing coherent superposition on all data after phase compensation is introduced, and performing NCI (non coherent integration) on all data before phase compensation is introduced to obtain coherent superposition results and NCI results; calculating to obtain a ratio of the coherent superposition result divided by the NCI result; and judging whether the ratio is greater than a preset ratio threshold value, if so, determining that the target exists in the unit to be tested, and if not, determining that the target does not exist in the unit to be tested. The ratio threshold is inversely related to the number of receiving antennas and the false alarm rate (probability) that the ratio exceeds the ratio threshold, and may be set empirically or obtained through calibration. Each piece of data before phase compensation is introduced is data acquired from a target position in the RDM of the echo signal received by each receiving antenna.
It should be noted that, in the process of acquiring the NCI chart, the data in the RDM of the echo signal received from each receiving antenna has been subjected to non-coherent superposition, so for each unit under test having the target to be confirmed, the corresponding NCI result may also be directly acquired from the corresponding position in the NCI chart for subsequent determination. The corresponding NCI result is directly obtained from the corresponding position in the NCI image without carrying out NCI on all data before phase compensation is introduced, so that the calculation amount can be reduced.
This is illustrated here by way of a specific example: if there are Q targets to be determined, extracting the data (1 ≦ i ≦ Q) of the ith unit under test having the target to be determined from the RDMs of the echo signals received by all the receiving antennas, and marking as ai(1),ai(2),...,ai(N), introducing phase compensation based on the desired observation angle β specifically:
where λ denotes the radar signal wavelength, N denotes the total number of receiving antennas, ai(N) denotes data obtained from RDM of the echo signal received by the nth receiving antenna, d denotes a spacing between two adjacent receiving antennas, and j denotes an imaginary unit.
Calculating coherent superposition results s for all data introduced with phase compensation of the ith unit to be tested with the target to be confirmed by using the following formula1(i)：
s1(i)＝(bi(1)+bi(2)+…+bi(N))2
To the ith tested unit with target to be confirmedIs calculated using the following formula2(i)：
s2(i)＝|ai(1)|2+|ai(2)|2+…+|ai(N)|2
Calculating the ratio of the coherent superposition result divided by the NCI result, and recording as s3(i)＝s1(i)/s2(i) (ii) a The condition that the ith unit to be tested with the target to be confirmed confirms that the target exists is s3(i) T is a preset proportion threshold value. T is set by considering the probability that the ratio of the coherent superposition result of random noise to the NCI result exceeds T (i.e., the false alarm rate). If the false alarm rate is certain, the more the number of the receiving antennas is, the lower the T needs to be set; if the number of the receiving antennas is fixed, the lower the required false alarm rate is, the higher the T needs to be set. For example, for a 4-channel receiving antenna, the allowable false alarm rate after random noise coherent superposition is less than 20%, and statistical analysis can show that T should be set to be at least greater than 0.4248, and the allowable setting range of T is 0.4248-0.9999 at the moment.
In a specific embodiment, for each unit to be tested located in a short distance range in the NCI chart, whether the signal-to-noise ratio of the unit to be tested is greater than a preset second CFAR threshold is determined, if yes, it is determined that the target exists in the unit to be tested, and if not, it is determined that the target does not exist in the unit to be tested. The short-distance range is the distance range within which the detection effect can be ensured by the traditional vehicle-mounted radar target detection method. Optionally, after the step of determining that the target exists in the unit to be tested, for the unit to be tested whose positions are adjacent and whose determination results are both targets, the determination result of the unit to be tested whose echo power is not the maximum value may be modified to be target-free, so as to filter out redundant information. The second CFAR threshold may be a CFAR threshold used in a conventional vehicle-mounted radar target detection method. For example, the CFAR threshold value adopted in the conventional vehicle-mounted radar target detection method is 13dB, and the second CFAR threshold value is set to 13 dB.
The effect of the vehicle-mounted radar target detection method provided by the invention is explained by a simulation embodiment. The number of receiving antennas in the antenna array is set to be N equal to 8, the wavelength lambda of the radar signal is set to be 4mm, and the distance d between the receiving antennas is set to be 2 mm. The information for the three targets is shown in the table below.
| Relative distance (m) | Relative velocity (m/s) | Azimuth (depth) | |
| |
85 | 0 | 0 |
| Object 2 | 83 | 5 | 60 |
| Target 3 | 90 | -5 | -60 |
The angle at which the detection capability is expected to be improved is set to 60 °, and the long-distance range is 80m to 100 m. The echo signals received by each receive antenna are first arranged in a matrix of dimension [ Na × Nr ], where each row contains a pulse of information. And performing two-dimensional Fourier transform on the two-dimensional time domain data of each receiving antenna to obtain two-dimensional RDM. All RDMs were subjected to NCI to obtain NCI maps. Data in the distance range of 80m to 100m in the NCI diagram are intercepted, as shown in FIG. 4. The display color bar on the right side of fig. 4 represents power in dB. The first CFAR threshold for detecting the target is set to 9dB, fig. 5 shows the detection result corresponding to the display color bar on the right side, where a value of 1 in the figure indicates that the target is detected in the unit under test, and a value of 0 indicates that the target is not detected in the unit under test.
The method of representation of fig. 6 to 8 is the same as that of fig. 5. The classification threshold is set to 13dB, and in fig. 6, the target with the snr exceeding the classification threshold is shown. And for the target to be confirmed, the signal-to-noise ratio of which does not exceed the classification threshold, extracting data corresponding to the target to be confirmed from the RDMs of the echo signals received by all the receiving antennas, performing phase compensation, and respectively calculating power values of the coherent superposition result and the NCI result. And calculating the ratio of the coherent superposition result and the NCI result of each target to be confirmed, if the ratio is greater than 0.75, determining the target as a real target, otherwise, determining the target as an invalid target or other non-concerned angle targets, and detecting the result as shown in FIG. 7. Fig. 8 shows the detection result obtained finally, and the target 3 is not detected. Compared with fig. 5 to 8, the vehicle-mounted radar target detection method provided by the invention can improve the detection capability at a specific angle, but the detection result can be accepted when the target at other angles is not concerned about possibly having a false alarm problem. In summary, compared with the conventional vehicle-mounted radar target detection method, the vehicle-mounted radar target detection method provided by the invention can improve the detection capability of a specific angle. Wherein, English Range in FIGS. 4-8 represents distance, and the unit is m; velocity denotes speed in m/s.
While, for purposes of simplicity of explanation, the foregoing method embodiments have been described as a series of acts or combination of acts, it will be appreciated by those skilled in the art that the present invention is not limited by the illustrated ordering of acts, as some steps may occur in other orders or concurrently with other steps in accordance with the invention.
The following are embodiments of the apparatus of the present invention that may be used to perform embodiments of the method of the present invention. For details which are not disclosed in the embodiments of the apparatus of the present invention, reference is made to the embodiments of the method of the present invention.
Fig. 9 is a diagram of a vehicle-mounted radar target detection device according to an embodiment of the present invention, where the device includes an echo signal acquisition unit, an NCI unit, a first determination unit, a second determination unit, a phase compensation unit, and a third determination unit.
And the echo signal acquisition unit is used for acquiring the echo signal received by each receiving antenna in the antenna array, and respectively carrying out two-dimensional Fourier transform on the echo signal received by each receiving antenna to obtain the RDM of the echo signal received by each receiving antenna.
And the NCI unit is used for carrying out NCI on the RDMs of the echo signals received by all the receiving antennas to obtain an NCI diagram.
And the first judging unit is used for judging whether the signal-to-noise ratio of each tested unit positioned in a preset remote distance range in the NCI diagram is greater than a preset first CFAR threshold, if not, the tested unit is determined to have no target, and if yes, the tested unit is determined to possibly have the target.
And the second judging unit is used for judging whether the signal-to-noise ratio of the detected unit is greater than a preset classification threshold value or not for the detected unit with the possible target, wherein the classification threshold value is greater than the first CFAR threshold value, if so, the detected unit is determined to have the target, and if not, the detected unit is determined to have the target to be confirmed.
And the phase compensation unit is used for acquiring data from a target position in the RDM of the echo signal received by each receiving antenna for each tested unit with the target to be confirmed, and introducing phase compensation to the data based on a preset angle, wherein the target position is a position corresponding to the tested unit with the target to be confirmed.
And the third judging unit is used for judging whether the target exists or not by utilizing the data after the phase compensation for each tested unit with the target to be confirmed.
Optionally, the third determining unit specifically includes a superposition subunit, a calculation subunit, and a determining subunit.
The superposition subunit is used for obtaining a coherent superposition result for each tested unit with the target to be confirmed; acquiring a non-coherent superposition result corresponding to each tested unit with a target to be confirmed; the acquisition mode of the non-coherent superposition result comprises the following steps: and acquiring a non-coherent superposition result corresponding to each tested unit with the target to be confirmed from the NCI diagram, or performing non-coherent superposition on all data before phase compensation is introduced for each tested unit with the target to be confirmed to obtain a non-coherent superposition result.
And the calculating subunit is used for calculating the ratio of the coherent superposition result divided by the NCI result.
And the judging subunit is used for judging whether the ratio of the coherent superposition result divided by the NCI result is greater than a preset ratio threshold value, if so, determining that the target exists in the unit to be tested, and if not, determining that the target does not exist in the unit to be tested.
Optionally, the vehicle-mounted radar target detection device further includes: and the first modification unit is used for modifying the judgment result of the tested unit of which the echo power is not the maximum value into the target-free tested unit with adjacent positions and the judgment results of which are all possible targets before the second judgment unit is executed.
Optionally, the vehicle-mounted radar target detection device further includes: and the fourth judging unit is used for judging whether the signal-to-noise ratio of each detected unit located in the preset close distance range in the NCI diagram is greater than a preset second CFAR threshold value, if so, determining that the detected unit has a target, and if not, determining that the detected unit does not have the target.
Optionally, the vehicle-mounted radar target detection device further includes: and the second modification unit is used for modifying the judgment result of the tested unit of which the echo power is not the maximum value into the target-free unit for the tested units of which the positions are adjacent and the judgment results are both targets.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one position, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiments in the present description are mainly described as different from other embodiments, the same and similar parts in the embodiments may be referred to each other, and the features described in the embodiments in the present description may be replaced with each other or combined with each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A vehicle-mounted radar target detection method is characterized by comprising the following steps:
acquiring an echo signal received by each receiving antenna in an antenna array, and respectively performing two-dimensional Fourier transform on the echo signal received by each receiving antenna to obtain a range-Doppler diagram of the echo signal received by each receiving antenna;
performing non-coherent superposition on the range-Doppler images of the echo signals received by all the receiving antennas to obtain a non-coherent superposition image;
judging whether the signal-to-noise ratio of each unit to be tested in a preset remote distance range in the non-coherent overlay map is greater than a preset first constant false alarm rate threshold value, if not, determining that the unit to be tested does not have a target, and if so, determining that the unit to be tested possibly has the target;
for the tested unit with a possible target, judging whether the signal-to-noise ratio of the tested unit is greater than a preset classification threshold, wherein the classification threshold is greater than the first constant false alarm rate threshold, if so, determining that the tested unit has the target, and if not, determining that the tested unit has the target to be confirmed;
for each tested unit with a target to be confirmed, acquiring data from a target position in a range-doppler diagram of an echo signal received by each receiving antenna, and introducing phase compensation to the data based on a preset angle, wherein the target position is a position corresponding to the tested unit with the target to be confirmed;
and for each tested unit with the target to be confirmed, judging whether the target exists or not by using the data after the phase compensation is introduced.
2. The vehicle-mounted radar target detection method according to claim 1, wherein the determining, for each unit under test having a target to be confirmed, whether the target exists using data after introducing phase compensation specifically comprises:
for each tested unit with the target to be confirmed, performing coherent superposition on all data with introduced phase compensation to obtain coherent superposition results;
acquiring a non-coherent superposition result corresponding to each tested unit with a target to be confirmed; wherein, the non-coherent superposition result obtaining mode comprises: acquiring a non-coherent superposition result corresponding to each detected unit with a target to be confirmed from the non-coherent superposition map, or performing non-coherent superposition on all data before introducing phase compensation for each detected unit with the target to be confirmed to obtain the non-coherent superposition result;
calculating the ratio of the coherent superposition result divided by the non-coherent superposition result;
and judging whether the ratio is larger than a preset ratio threshold value, if so, determining that the target exists in the unit to be tested, and if not, determining that the target does not exist in the unit to be tested.
3. The vehicle-mounted radar target detection method according to claim 1, wherein before the step of determining whether the signal-to-noise ratio of the unit under test is greater than a preset classification threshold for the unit under test in which the target may exist, the method further comprises:
and for the tested units with adjacent positions and the judgment results of which are possible to have targets, modifying the judgment result of the tested unit with the echo power not being the maximum value into the non-existence target.
4. The vehicle-mounted radar target detection method of claim 1, further comprising:
and judging whether the signal-to-noise ratio of each unit to be detected in the non-coherent overlay map within a preset short distance range is greater than a preset second constant false alarm rate threshold value, if so, determining that the target exists in the unit to be detected in the non-coherent overlay map within the preset short distance range, and if not, determining that the target does not exist in the unit to be detected.
5. The vehicle-mounted radar target detection method according to claim 4, wherein after the step of determining that the target exists in the unit under test located within the preset short distance range in the non-coherent overlay map, the method further comprises:
and for the tested units with adjacent positions and the judgment results of which are targets, modifying the judgment result of the tested unit with the echo power not being the maximum value into the absence of the targets.
6. An on-vehicle radar target detection device, characterized by comprising:
the echo signal acquisition unit is used for acquiring echo signals received by each receiving antenna in the antenna array, and respectively carrying out two-dimensional Fourier transform on the echo signals received by each receiving antenna to obtain a range Doppler diagram of the echo signals received by each receiving antenna;
the non-coherent superposition unit is used for carrying out non-coherent superposition on the range-Doppler diagrams of the echo signals received by all the receiving antennas to obtain a non-coherent superposition diagram;
the first judgment unit is used for judging whether the signal-to-noise ratio of each unit to be tested positioned in a preset long-distance range in the non-coherent overlay map is greater than a preset first constant false alarm rate threshold value, if not, the unit to be tested is determined to have no target, and if yes, the unit to be tested is determined to possibly have the target;
a second judging unit, configured to judge, for a unit under test where a target may exist, whether a signal-to-noise ratio of the unit under test is greater than a preset classification threshold, where the classification threshold is greater than the first constant false alarm rate threshold, if yes, determine that the unit under test has the target, and if not, determine that the unit under test has the target to be confirmed;
the phase compensation unit is used for acquiring data from a target position in a range-doppler diagram of an echo signal received by each receiving antenna for each tested unit with a target to be confirmed, and introducing phase compensation to the data based on a preset angle, wherein the target position is a position corresponding to the tested unit with the target to be confirmed;
and the third judging unit is used for judging whether the target exists or not by using the data after the phase compensation is introduced for each tested unit with the target to be confirmed.
7. The vehicle-mounted radar target detection device according to claim 6, wherein the third determination unit specifically includes:
the superposition subunit is used for carrying out coherent superposition on all the data introduced with the phase compensation for each tested unit with the target to be confirmed to obtain coherent superposition results; acquiring a non-coherent superposition result corresponding to each tested unit with a target to be confirmed; wherein, the non-coherent superposition result obtaining mode comprises: acquiring a non-coherent superposition result corresponding to each detected unit with a target to be confirmed from the non-coherent superposition map, or performing non-coherent superposition on all data before introducing phase compensation for each detected unit with the target to be confirmed to obtain the non-coherent superposition result;
the calculating subunit is used for calculating a ratio of the coherent superposition result divided by the non-coherent superposition result;
and the judging subunit is used for judging whether the ratio is greater than a preset ratio threshold, if so, determining that the target exists in the unit to be detected, and if not, determining that the target does not exist in the unit to be detected.
8. The vehicle-mounted radar target detection device of claim 6, further comprising:
a first modifying unit, configured to modify, before executing the second determining unit, a determination result of the unit under test, for which positions are adjacent and determination results are all possible targets, to be non-target-present, the determination result of the unit under test, for which echo power is not a maximum value.
9. The vehicle-mounted radar target detection device of claim 6, further comprising:
and a fourth judging unit, configured to judge, for each unit to be measured in the non-coherent overlay map, whether a signal-to-noise ratio of the unit to be measured is greater than a preset second constant false alarm rate threshold, if yes, determine that a target exists in the unit to be measured in the preset short distance range in the non-coherent overlay map, and if not, determine that the target does not exist in the unit to be measured.
10. The vehicle-mounted radar target detection device according to claim 9, characterized by further comprising:
and the second modification unit is used for modifying the judgment result of the tested unit of which the echo power is not the maximum value into the target-free unit for the tested unit which is positioned in the preset close distance range in the non-coherent overlay image with adjacent positions and the judgment result of which is the target.
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