Target angle measurement method of sparse antenna array, vehicle-mounted millimeter wave radar and product

Abstract

The invention provides a target angle measurement method of a sparse antenna array, a vehicle-mounted millimeter wave radar and a product, the sparse antenna array comprises n unit antenna groups which are arranged repeatedly, each unit antenna group comprises m unit antennas, and the distance between the unit antenna groups is not equal to the distance between the adjacent unit antennas in the unit antenna groups. Comprising the following steps: determining unit antenna sub-arrays corresponding to unit antennas respectively based on the unit antennas contained in each unit antenna group in a sparse antenna array; acquiring signals respectively received by each unit antenna sub-array, processing the signals to obtain a first angle spectrum corresponding to each unit antenna sub-array, and performing non-coherent accumulation on the first angle spectrum of each unit antenna sub-array to obtain a second angle spectrum; performing angle peak detection on the second angle spectrum to obtain a potential angle set; and determining a real target angle from the potential angle set according to the angle spectrum data of the unit antenna subarrays corresponding to the potential angles in the potential angle set.

Description

Technical Field

[0001] The present application relates to the field of vehicle-mounted radar technology, and in particular to a target angle measurement method of a sparse antenna array, a vehicle-mounted millimeter-wave radar, and a computer program product. Background Art

[0002] Millimeter-wave radar detects and tracks targets by emitting and receiving electromagnetic waves, and can simultaneously measure the distance, speed, and angle of the target. Compared with cameras and lidars, millimeter-wave radars have good environmental and weather adaptability, and can adapt to application scenarios such as strong light, night, heavy rain, fog, and dust. They have been widely used in vehicle-mounted ADAS (Advanced Driving Assistance System) assisted driving systems and vehicle-mounted AD (Autonomous Driving) automatic driving systems. Through the mutual integration of cameras, lidars, and millimeter-wave radars, the redundancy of intelligent decision-making can be improved, and the high reliability and safety of ADAS assisted driving or AD automatic driving can be achieved.

[0003] At present, the application of millimeter-wave radar in vehicles is mainly limited by angular resolution, which is also the main disadvantage of millimeter-wave radar compared with cameras and lidar. In order to improve the angular resolution capability of millimeter-wave radar, the direction-finding aperture of millimeter-wave radar needs to be increased. Vehicle-mounted millimeter-wave radar generally adopts a uniform half-wavelength antenna array. In order to achieve a large direction-finding aperture, more transceiver channels are required, resulting in a sharp increase in hardware costs.

[0004] In order to improve the problem of high hardware cost caused by uniform half-wavelength array to achieve large direction finding aperture, a sparse array method can be adopted to achieve a low-cost, high-angle resolution direction finding solution. However, sparse array will cause high side lobes or false grating lobes, among which non-uniform sparse array will cause high side lobes, and uniform sparse array will cause false grating lobes.

[0005] In order to apply the sparse array method to vehicle-mounted millimeter-wave radar, realize a low-cost large direction-finding aperture, and improve the angular resolution capability of the vehicle-mounted millimeter-wave radar, it is necessary to solve the problem of false targets caused by high side lobes or grating lobes in the sparse array. Summary of the invention

[0006] In order to solve the existing technical problems, the present application provides a target angle measurement method of a sparse antenna array, a vehicle-mounted millimeter-wave radar and a computer program product that can effectively solve the problem of false targets.

[0007] In a first aspect, a method for measuring the angle of a target with a sparse antenna array is provided, wherein the sparse antenna array includes n unit antenna groups that are repeatedly arranged, wherein the unit antenna group includes m unit antennas, and the spacing between the unit antenna groups is not equal to the spacing between adjacent unit antennas in the unit antenna group. The method includes:

[0008] Based on the unit antennas included in each unit antenna group in the sparse antenna array, determine the unit antenna subarrays corresponding to each of the unit antennas; wherein each of the unit antenna subarrays is composed of unit antennas with the same serial number in each of the unit antenna groups;

[0009] Acquire signals respectively received by each of the unit antenna subarrays, process the signals to obtain first angle spectra corresponding to each of the unit antenna subarrays, and then perform non-coherent accumulation on the first angle spectra of each of the unit antenna subarrays to obtain second angle spectra;

[0010] Performing angle peak detection on the second angle spectrum to obtain a potential angle set;

[0011] The real target angle is determined from the potential angle set according to the angle spectrum data of the unit antenna subarray corresponding to each potential angle in the potential angle set.

[0012] In a second aspect, a vehicle-mounted millimeter-wave radar is provided, comprising a millimeter-wave radar processor and a memory, wherein the memory stores a computer program executable by the millimeter-wave radar processor;

[0013] When the computer program is executed by the millimeter wave radar processor, the target angle measurement method of the sparse antenna array described in any embodiment of the present application is implemented;

[0014] The antenna array used for angle measurement is formed by a MIMO working mode or a non-MIMO working mode.

[0015] According to a third aspect, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the target angle measurement method of the sparse antenna array described in any embodiment of the present application.

[0016] The target angle measurement method of the sparse antenna array provided in the above embodiment utilizes n unit antenna groups to be repeatedly arranged to form a sparse antenna array, and according to the unit antennas contained in the unit antenna group, the sparse antenna array is split into multiple unit antenna subarrays, and signals are received respectively by the unit antenna subarrays, and the signals are processed to obtain a first angle spectrum corresponding to each unit antenna subarray, and then the first angle spectrum of each unit antenna subarray is non-coherently accumulated to obtain a second angle spectrum, and the second angle spectrum is angle peak detected to obtain a potential angle set, and the real target angle is determined from the potential angle set according to the angle spectrum data of the unit antenna subarray corresponding to each potential angle in the potential angle set. In this way, by equivalently converting the sparse antenna array into multiple unit antenna subarrays as sparse uniform arrays, the first angle spectrum obtained by processing the signal received by each unit antenna subarray can be used for subsequent screening of the real target angle, thereby utilizing the sparse uniform array to effectively reduce the number of antenna channels and reduce the radar cost, and the unit antenna subarray can be used to obtain the angle spectrum data obtained by the receiving unit to achieve high-resolution angle measurement and eliminate grating lobe false targets.

[0017] The vehicle-mounted millimeter-wave radar and computer program product provided in the above embodiments belong to the same concept as the corresponding target angle measurement method embodiment of a sparse antenna array, and thus have the same technical effects as the corresponding target angle measurement method embodiment of a sparse antenna array, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a diagram of an application scenario of a target angle measurement method with a sparse antenna array in one embodiment.

[0019] Figure 2 Schematic diagram of the structure of a vehicle-mounted millimeter-wave radar in one embodiment.

[0020] Figure 3 Flow chart of a target angle measurement method of a sparse antenna array in one embodiment.

[0021] Figure 4 Schematic diagram of a sparse antenna array in one embodiment.

[0022] Figure 5 for Figure 4 The schematic diagram shows that the sparse antenna array is decomposed into multiple unit antenna sub-arrays.

[0023] Figure 6 for Figure 4 The sparse antenna array shown is equivalent to a schematic diagram of an inter-subarray phase interferometer.

[0024] Figure 7 Schematic diagram of an angle spectrum in one embodiment.

[0025] Figure 8Schematic diagram of a known half-wavelength non-sparse uniform antenna array.

[0026] Fig. 9 The figure is a schematic diagram showing the principle of a target angle measurement method using a sparse antenna array in an optional specific example.

[0027] Fig.10 The present invention is a flowchart of a target angle measurement method of a sparse antenna array in an optional specific example.

[0028] Fig.11 The figure is a working flow chart of the vehicle-mounted millimeter wave radar in one embodiment.

[0029] Fig.12 A schematic diagram of a sparse antenna array in an optional specific example.

[0030] Fig.13 It is a schematic diagram of a transmitting array and a receiving array forming a sparse antenna array in a non-MIMO working mode.

[0031] Fig.14 It is a schematic diagram of a transmitting array and a receiving array forming a sparse antenna array in a MIMO working mode.

[0032] Fig.15 for Fig.12 The schematic diagram shows that the sparse antenna array is decomposed into multiple unit antenna sub-arrays.

[0033] Fig.16 for Fig.12 The sparse antenna array shown is equivalent to a schematic diagram of an inter-subarray phase interferometer.

[0034] Fig.17 This is a schematic diagram of the angle spectrum corresponding to the target wave direction of 10°.

[0035] Fig.18 A schematic diagram of the structure of a vehicle-mounted millimeter-wave radar provided in one embodiment. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0037] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of this application.

[0038] In the following description, the expression "some embodiments" is involved, which describes a subset of all possible embodiments. It should be noted that "some embodiments" may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0039] In the following description, the terms "first, second, third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first, second, third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0040] See also Figure 1 , which is an optional application scenario diagram of the target angle measurement method of the sparse antenna array provided in an embodiment of the present application applied to a vehicle-mounted millimeter wave radar. The vehicle-mounted millimeter wave radar 200 is usually installed on both sides of the front of the vehicle 100. Common installation locations are not limited to Figure 1 The forward position shown also includes the front corner, rear corner and rear corner positions, which are used to detect and perceive the surrounding environment targets (target 1, target 2, target 3).

[0041] See also Figure 2 , is a schematic diagram of the structure of the vehicle-mounted millimeter-wave radar. The vehicle-mounted millimeter-wave radar mainly consists of four functional parts:

[0042] 1) Antenna array, consisting of a transmitting array and a receiving array. Vehicle-mounted millimeter-wave radar generally adopts a MIMO (Multiple-Input Multiple-Output) working mode, and realizes the antenna array required for direction finding through the MIMO working mode between the unit antennas of the transmitting array. The sparse antenna array provided in the embodiment of the present application refers to the final direction-finding antenna array, which can be formed by a MIMO working mode or a non-MIMO working mode. The specific method of forming the sparse antenna array does not affect the use of the target angle measurement method of the sparse antenna array provided in the embodiment, and the specific form of the unit antenna does not affect the use of the target angle measurement method of the sparse antenna array provided in the embodiment of the present application.

[0043] 2) MRTR (Millimeter-wave Radar Transceiver, millimeter-wave radar transceiver module or chip), millimeter-wave radar transceiver functional module, mainly composed of transmitting components, receiving components and linear frequency modulation local oscillator source components. MRTR generates and transmits the working waveform signal of the millimeter-wave radar, receives and discretely samples the reflected waveform signal of the target, and sends the sampled reflected waveform signal to the MRP (Millimeter-wave Radar Processor) millimeter-wave radar processor.

[0044] 3) MRP (Millimeter-wave Radar Processor), a millimeter-wave radar processor, receives the reflected waveform signal from MRTR and performs digital processing to obtain information such as the distance, speed and angle of environmental targets, clusters, identifies and tracks targets, and outputs point cloud-level detection results or target-level detection results. From the perspective of main functions, MRP is mainly composed of a distance measurement module, a speed measurement module, an angle measurement module and a target clustering identification and tracking module. The above modules can be implemented through embedded software, FPGA (Field Programmable Gate Array) or AISC (Application Specific Integrated Circuit). The target angle measurement method for the sparse antenna array provided in the embodiment of the present application is mainly completed in the MRP angle measurement module. The implementation form, composition method or module division method of MRP does not affect the use of the target angle measurement method for the sparse antenna array provided in the embodiment of the present application.

[0045] 4) A read-write memory for storing the working data of the millimeter-wave radar, including working parameter data and process data stored in advance, typically such as the structural size parameters of the sparse antenna array provided in the embodiment of the present application, and the threshold parameters required for the sparse antenna array angle measurement method provided in the embodiment of the present application.

[0046] It should be noted that the configuration form or composition method of the functional parts of the above-mentioned vehicle-mounted millimeter-wave radar does not affect the use of the target angle measurement method of the sparse antenna array provided in the embodiment of the present application; in terms of application scenarios, the use of the target angle measurement method of the sparse antenna array provided in the embodiment of the present application can be applied to all applications that use electromagnetic waves for target direction finding, and is not limited to vehicle-mounted millimeter-wave radar applications.

[0047] See also Figure 3 , a target angle measurement method of a sparse antenna array provided in an embodiment of the present application, comprising the following steps:

[0048] S101, based on the unit antennas included in each unit antenna group in the sparse antenna array, determine the unit antenna subarrays corresponding to each of the unit antennas; wherein each of the unit antenna subarrays is composed of unit antennas with the same serial number in each of the unit antenna groups.

[0049] A sparse antenna array is an array where the distance between adjacent unit antennas is greater than half the wavelength of the transmitted waveform signal. A sparse uniform array is an array where the distance between adjacent unit antennas is equal and greater than half the wavelength of the transmitted waveform signal. A half-wavelength non-sparse uniform array is an array where the distance between adjacent unit antennas is equal and equal to half the wavelength of the transmitted waveform signal.

[0050] In this embodiment, the sparse antenna array includes n unit antenna groups that are repeatedly arranged, each unit antenna group includes m unit antennas, and the spacing between the unit antenna groups is not equal to the spacing between adjacent unit antennas in the unit antenna group.

[0051] See also Figure 4 , is a schematic diagram of a sparse antenna array composed of n unit antenna groups repeatedly arranged, each unit antenna group includes m unit antennas. For example, m is equal to 3, and the unit antennas in each unit antenna group are composed of Figure 4 The three unit antennas represented by the triangle, circle and rectangle are respectively called the first unit antenna T, the second unit antenna C and the third unit antenna S for distinguishing description. In each unit antenna group, the spacing between the unit antennas includes the spacing d between the first unit antenna T and the second unit antenna C. 1 , the distance d between the second element antenna T and the third element antenna S 2 The spacing between the unit antenna groups is d 3 , refers to the distance between the last unit antenna of the previous unit antenna group and the first unit antenna of the next unit antenna group, such as the distance between the third unit antenna S of the previous unit antenna group and the first unit antenna T of the next unit antenna group. It should be noted that the number of unit antennas in each unit antenna group can be adaptively adjusted according to specific needs, increasing or decreasing the number of unit antennas in each unit antenna group, and the number of unit antenna groups in the sparse antenna array can also be adjusted according to specific needs, increasing or decreasing the number of unit antenna groups. The more unit antennas in each unit antenna group and / or the more unit antenna groups, the longer the direction-finding baseline of the inter-subarray phase interferometer formed by each of the unit antenna groups, which is conducive to improving the angle resolution accuracy and angle measurement accuracy, and improving the robustness of the angle measurement result to noise, but the cost is higher.

[0052] See also Figure 5According to the number of unit antennas in each unit antenna group, the sparse antenna array can be divided into multiple unit antenna subarrays. Each unit antenna subarray is a sparse uniform subarray. Each of the unit antenna subarrays is composed of unit antennas with the same serial number in each of the unit antenna groups. Figure 4 For example, the unit antennas in each unit antenna group include the first unit antenna T, the second unit antenna C and the third unit antenna S. The first unit antenna T with the same serial number in each unit antenna group constitutes the first unit antenna subarray, the second unit antenna C with the same serial number constitutes the second unit antenna subarray, and the third unit antenna S with the same serial number constitutes the third unit antenna subarray. In each unit antenna subarray, the spacing between adjacent unit antennas refers to the distance between two unit antennas with the same serial number in two adjacent unit antenna groups, and is expressed as d 0 Therefore, d 0 At least greater than the maximum distance d between unit antennas in the same unit antenna group 2 In a specific example, d 0 Greater than 1.5 times the wavelength of the transmitted waveform signal of the vehicle-mounted millimeter-wave radar (the wavelength is represented by the symbol λ), that is, d 0 >1.5λ.

[0053] S103, acquiring signals respectively received by the unit antenna subarrays, processing the signals to obtain first angle spectra corresponding to the unit antenna subarrays, and then performing non-coherent accumulation on the first angle spectra of the unit antenna subarrays to obtain second angle spectra.

[0054] The sparse antenna array is equivalently disassembled into multiple unit antenna subarrays, and the unit antenna subarrays are used as receiving units for echo signal data. The phase interference formed by the multiple unit antenna subarrays is used to obtain the signals received by each of the unit antenna subarrays respectively. The signals corresponding to each unit antenna subarray are processed to obtain the angle spectrum corresponding to each unit antenna subarray, and then the angle spectrum corresponding to each unit antenna subarray is non-coherently accumulated to obtain the angle spectrum for angle peak detection. For ease of description and distinction, in the embodiment of the present application, the angle spectrum corresponding to each unit antenna subarray obtained by processing the signals corresponding to each unit antenna subarray is referred to as the first angle spectrum, and the angle spectrum corresponding to each unit antenna subarray obtained by non-coherently accumulating the angle spectrum corresponding to each unit antenna subarray is referred to as the second angle spectrum. Among them, non-coherent accumulation refers to an accumulation method that directly performs amplitude or power superposition without using the phase relationship of the signal.

[0055] S105: Perform angle peak detection on the second angle spectrum to obtain a potential angle set.

[0056] By performing angle peak detection on the second angle spectrum after non-coherent accumulation, a peak detection result including all true angles and false angles can be obtained. The true angles and false angles obtained by angle peak detection are combined to form a potential angle set. Both true angles and false angles can be called potential angles.

[0057] S107, determining a real target angle from the potential angle set according to the angle spectrum data of the unit antenna subarray corresponding to each potential angle in the potential angle set.

[0058] The angle spectrum data of the unit antenna subarrays corresponding to the potential angles refer to the angle spectrum obtained after the signals received by the multiple unit antenna subarrays corresponding to the potential angles are processed as receiving units. After all the potential angles are obtained by angle peak detection, the angle spectrum obtained by processing the signals received by each unit antenna subarray can be used for subsequent screening of the real target angle.

[0059] The target angle measurement method of the sparse antenna array provided in the above embodiment utilizes n unit antenna groups to be repeatedly arranged to form a sparse antenna array, by equivalently converting the sparse antenna array into multiple unit antenna subarrays as a sparse uniform array, and by decomposing the multiple unit antenna groups of the sparse antenna array into multiple unit antenna subarrays, and using the multiple unit antenna subarrays as receiving units to receive signals to obtain an angle spectrum, after all potential angles are obtained by angle peak detection, the angle spectrum obtained by processing the corresponding signal received by each unit antenna subarray can be used for subsequent screening of the true target angle, so that the sparse uniform array can be used to effectively reduce the number of antenna channels and reduce the radar cost, and the unit antenna subarray can be used to obtain the angle spectrum data for the receiving unit to achieve high-resolution angle measurement and eliminate grating lobe false targets.

[0060] In some embodiments, step S107 includes:

[0061] According to the angle spectrum data of the unit antenna subarray corresponding to each potential angle in the potential angle set, angle measurement deambiguation is performed using a phase interferometer angle measurement algorithm through a subarray phase interferometer formed by each unit antenna group, and the real target angle is determined from the potential angle set.

[0062] The relative spatial positions between the multiple unit antenna subarrays after decomposition of each unit antenna group contained in the sparse antenna array can be equivalent to an inter-subarray phase interferometer, such as Figure 6 As shown, the relative spatial positions between the sub-arrays T, C and S corresponding to the first unit antenna T, the second unit antenna C and the third unit antenna S respectively can be equivalent to an inter-sub-array phase interferometer TCS.

[0063] The phase interferometer angle measurement algorithm is a technology that uses the phase information of the radio signal reaching the direction-finding antenna to perform direction-finding. This algorithm is not affected by signal strength attenuation and has higher direction-finding accuracy than the amplitude method. The phase interferometer angle measurement algorithm is usually based on the direction-finding principle of a one-dimensional interferometer. When the target signal radiates to the antenna array, due to the certain distance between the array elements of the antenna array, there is a certain time difference between the received signals of each array element on the same baseline. This time difference can be converted into a phase difference under certain conditions, that is, the phase interferometer direction-finding algorithm can use the phase difference between the received signals of the array elements on each baseline to complete the direction-finding of the target.

[0064] Angle measurement deambiguation refers to the process of recovering the true angle value from the blurred angle measurement result through a specific technology or algorithm during the angle measurement process. The angle measurement deambiguation algorithm can be selected from various known algorithms, such as increasing the baseline length, using long and short baselines, high and low frequencies, and frequency modulation, which can effectively improve the accuracy of angle measurement and reduce ambiguity. This application does not impose any restrictions on this. Based on the angle spectrum data of the unit antenna subarray corresponding to each potential angle in the potential angle set, a phase interferometer between subarrays equivalent to multiple unit antenna subarrays is used to perform angle measurement deambiguation using a phase interferometer angle measurement algorithm, delete false angles, obtain the true incoming wave direction angle, and determine the true target angle.

[0065] In this way, the target angle measurement method of the sparse antenna array provided in the above embodiment uses a plurality of unit antenna subarrays as receiving units to process the received signals to obtain a first angle spectrum, obtains a second angle spectrum for angle peak detection through non-coherent accumulation, and after all potential angles are determined, a subarray phase interferometer composed of a plurality of unit antenna subarrays as receiving units can be used to form an inter-subarray phase interferometer, thereby being suitable for a phase interferometer angle measurement algorithm to determine the true target angle from all potential angles.

[0066] In some embodiments, the unit antenna includes a first unit antenna T, a second unit antenna C, and a third unit antenna S, and the unit antenna subarray includes a first unit antenna subarray consisting of the first unit antenna T, a second unit antenna subarray consisting of the second unit antenna C, and a third unit antenna subarray consisting of the third unit antenna S; step S107 includes:

[0067] According to the angle spectrum data A of the first unit antenna subarray corresponding to each potential angle in the potential angle set T , the angle spectrum data A of the second unit antenna subarray C and the angle spectrum data A of the third unit antenna subarray S ;

[0068] The phase interferometer between the sub-arrays formed by each of the unit antenna groups is used to perform angle measurement deambiguation using a phase interferometer angle measurement algorithm, and the angle spectrum data A corresponding to the potential angles are respectively T , A C , A S Whether the phase interference relationship is satisfied to determine the actual target angle from the potential angle set.

[0069] Optionally, the phase interference relationship is shown in the following formula 1 and formula 2:

[0070]

[0071] Where f represents the frequency of the transmitted and received waveform signals, λ represents the wavelength of the transmitted waveform signal, and d 1 is the distance between the first unit antenna T and the second unit antenna C in the unit antenna group, d 2 is the distance between the second unit antenna T and the third unit antenna S in the unit antenna group.

[0072] In the inter-subarray phase interferometer TCS based on the equivalence of the relative spatial positions between subarrays T, C and S, the phase interference of subarrays T, C and S, and the signals received by each subarray satisfy the theoretical relationship shown in formulas 1 and 2. T represents the signal received by subarray T or the complex angle spectrum of subarray T, A C represents the signal received by subarray C or the complex angle spectrum of subarray C, A S represents the signal received by sub-array S or the complex angle spectrum of sub-array S.

[0073] In the above embodiment, the second angle spectrum is obtained by processing the signals of multiple unit antenna subarrays to obtain the corresponding first angle spectrum, and then performing non-coherent accumulation based on the first angle spectrum. The potential angle is obtained by angle peak detection for the second angle spectrum. The angle spectrum data of the unit antenna subarrays corresponding to each potential angle in the potential angle set are used to determine whether they satisfy the phase interference relationship, so as to determine the true target angle from the potential angle set.

[0074] In some embodiments, in the inter-subarray phase interferometer, d 1 and d 2 The following relationships are satisfied, as shown in Formula 3 and Formula 4:

[0075]

[0076] Where 0<θ max ≤90°.

[0077] The inter-subarray phase interferometer is composed of a plurality of unit antenna subarrays after decomposition of each unit antenna group, wherein the size representing the relative spatial position between different unit antenna subarrays, d 1 and d 2 The phase interferometer needs to meet the ambiguity resolution requirements within the direction finding angle coverage range. The maximum coverage range of the incoming wave direction angle θ is θ max , for d 1 and d 2 The constraint relationship is shown in Formula 3 and Formula 4.

[0078] In an alternative specific example, d 1 is 0.5λ, d 2 Thus, the combination of the multiple unit antenna subarrays decomposed from each unit antenna group can be equivalent to an inter-subarray phase interferometer of a half-wavelength non-sparse uniform array.

[0079] In an optional specific example, in each unit antenna subarray, the distance between adjacent unit antennas is d 0 , d 0 is 4λ. Among them, d 0 The size of is related to the number of unit antennas in each unit antenna group, the distance between adjacent unit antennas in each unit antenna group, and the distance between adjacent unit antenna groups. Taking the inter-subarray phase interferometer TCS composed of subarray T, subarray C and subarray S as an example, the inter-subarray phase interferometer TCS is a 3-unit phase interferometer or a 2-baseline phase interferometer. It should be noted that the sparse antenna array in the embodiment of the present application is not limited to the 3-unit phase interferometer or 2-baseline phase interferometer, and the number of unit antennas in the phase interferometer can be increased or decreased. The more unit antennas there are, the longer the direction-finding baseline of the inter-subarray phase interferometer is, which can effectively improve the angle resolution accuracy and angle measurement accuracy, and improve the robustness of the angle measurement result to noise, but the cost is higher; the fewer the number of unit antennas, the lower the cost, but the shorter the direction-finding baseline of the inter-subarray phase interferometer is, the lower the robustness of the angle measurement result to noise.

[0080] In some embodiments, step S103 includes:

[0081] The discrete digital signal obtained by performing discrete digital signal sampling processing on the received waveform signal reflected by the target is subjected to one-dimensional distance FFT processing to obtain a one-dimensional distance FFT result;

[0082] Performing two-dimensional velocity FFT processing on the one-dimensional distance FFT result to obtain a two-dimensional velocity FFT result;

[0083] Performing constant false alarm detection on the two-dimensional velocity FFT result to obtain check point data;

[0084] Use each of the unit antenna subarrays to perform angle-dimensional FFT processing on the check point data to obtain a first angle spectrum corresponding to each of the unit antenna subarrays, and perform non-coherent accumulation on the first angle spectrum to obtain a second angle spectrum.

[0085] Among them, the signals received by each unit antenna subarray respectively refer to the information required for angle measurement obtained through subarray T, subarray C, and subarray S, which is generally the relative amplitude information and relative phase information between the antenna channels inside subarray T, subarray C, and subarray S, and then through FFT (Fast Fourier Transform) angle measurement operation or DBF (Digital Beam Forming) angle measurement operation. In this embodiment, the angle measurement operation mainly includes one-dimensional distance FFT processing, two-dimensional velocity FFT processing and constant false alarm detection, so as to obtain the angle spectrum (i.e., the first angle spectrum) corresponding to the subarray T, subarray C, and subarray S respectively; the angle spectrum corresponding to each of the subarray T, subarray C, and subarray S is non-coherently accumulated, so as to improve the sensitivity of angle peak detection, and obtain the angle spectrum (i.e., the second angle spectrum) used for angle peak detection.

[0086] In some embodiments, step S107 includes:

[0087] Select any potential angle in the potential angle set, and obtain the angle dimension FFT result of the corresponding unit antenna subarray;

[0088] According to the size parameters of the inter-sub-array phase interferometer formed by each of the unit antenna groups and the angle-dimensional FFT result, the inter-sub-array phase interferometer is directionally measured;

[0089] Obtaining an angle deviation between a potential angle and a direction-finding angle of the inter-sub-array phase interferometer;

[0090] Determining whether the angle deviation is less than a set threshold;

[0091] If the angle deviation is less than the set threshold, the current direction finding result of the inter-sub-array phase interferometer is taken as a qualified direction finding result;

[0092] The angle measurement deambiguation of all potential angles is completed in a loop, and the true target angle is determined from the potential angle set.

[0093] Among them, there is a grating lobe in the uniform sparse subarray corresponding to the unit antenna subarray, and the real angle of the target is θ, but there is a false angle θ caused by the grating lobe f1 ,θ f2 ,θ f3 ,θ f4 , all the over-detection points after the peak detection of the second angle spectrum will include the real angle θ and the false angle θ f1,θ f2 ,θ f3 ,θ f4 , it is impossible to distinguish the true angle θ from the false angle θ based on the peak detection result alone f1 ,θ f2 ,θ f3 ,θ f4 For the convenience of description, the real angle θ and the false angle θ are used. f1 ,θ f2 ,θ f3 ,θ f4 To represent the potential angle obtained by angle peak detection, but before the angle measurement is defuzzified, the real angle and the false angle cannot be clearly determined; the real angle θ obtained by angle peak detection and all false angles θ f1 ,θ f2 ,θ f3 ,θ f4 A potential angle set is formed by combining, and the angle dimension FFT data of subarray T, subarray C, and subarray S corresponding to each potential angle in the potential angle set are obtained according to the index of the potential angle set in the second angle spectrum; based on the angle dimension FFT data of subarray T, subarray C, and subarray S corresponding to each potential angle, the inter-subarray phase interferometer TCS is used to perform angle measurement deambiguation, and the false angle θ is eliminated according to whether the angle deviation between each potential angle and the direction-finding angle of the inter-subarray phase interferometer is less than a set threshold. f1 ,θ f2 ,θ f3 ,θ f4 , and obtain the real incoming wave direction angle θ.

[0094] like Figure 7 As shown in the figure, in the angle spectrum used for angle peak detection, the target wave direction only comes from the main lobe azimuth, and the directions shown by grating lobe-1, grating lobe-2, grating lobe-3, and grating lobe-4 are false targets. The position and number of false grating lobe targets are related to the target wave, the spacing and number of unit antennas of the T sub-array, C sub-array, and S sub-array, and the wavelength λ of the waveform signal transmitted by the vehicle-mounted millimeter-wave radar. By using the phase interferometer angle measurement algorithm to perform angle measurement deambiguation between sub-array phase interferometers, the grating lobe false deambiguation can be performed on the high-resolution direction finding results of the T sub-array, C sub-array, and S sub-array, and the false targets in the directions shown by grating lobe-1, grating lobe-2, grating lobe-3, and grating lobe-4 can be eliminated to obtain the main lobe azimuth direction finding result, that is, to determine the true target angle.

[0095] In order to have a more comprehensive understanding of the target angle measurement method of the sparse antenna array provided in the embodiment of the present application, please refer to Figures 8 to 17 ,by Figure 2 The structure of the vehicle-mounted millimeter wave radar shown in FIG. Figure 4Taking the sparse antenna array shown as an example, the main working process of the vehicle-mounted millimeter-wave radar and the process of the target angle measurement method of the sparse antenna array are explained.

[0096] Among them, the sparse antenna array can be formed by a MIMO working mode or a non-MIMO working mode. It may be a complete physical antenna array or a partial sub-array of a physical antenna array. The specific method of forming a sparse antenna array does not affect the use of the target angle measurement method of the sparse antenna array provided in the embodiment of the present application.

[0097] When the wavelength λ of the transmitted waveform signal remains the same, the array angular resolution depends on the size of the array aperture. The larger the array aperture, the smaller its angular resolution, and the stronger the vehicle-mounted millimeter-wave radar's ability to resolve multiple targets. In this example, the aperture size of the sparse uniform subarrays used for high-resolution direction finding, the T subarray, the C subarray, and the S subarray, is D 0 =(n-1)*d 0 .

[0098] See also Figure 8 , given a half-wavelength non-sparse uniformly arranged antenna array, in order to achieve the same direction-finding aperture for the T, C, and S subarrays, the number of antennas required is m = D 0 / (0.5λ)+1=(n-1)*d 0 / (0.5λ)+1. Since d 0 >0.5λ, so m>n. The number of antenna channels of the half-wavelength non-sparse uniform array is much larger than that of the sparse uniform array. The sparse uniform array can effectively reduce the number of antenna channels, thereby reducing the cost of the radar.

[0099] Specifically, the following example illustrates the sparse uniform array provided in the embodiment of the present application relative to Figure 8 The advantages of the known half-wavelength non-sparse uniform array are shown:

[0100] For example Figure 8 For the half-wavelength non-sparse uniform array shown, the relationship between the angular resolution Δθ (unit rad) and the number of unit antennas m is shown in the following formula 5:

[0101]

[0102] Taking the vehicle-mounted millimeter-wave radar to achieve an angular resolution of 1° (corresponding to 0.0175 rad) as an example, the number of antennas of a half-wavelength non-sparse uniform array is calculated based on Formula 5, and it can be seen that m=114.

[0103]

[0104] As an example of a sparse uniform array based on a repeated arrangement of n unit antenna groups proposed in an embodiment of the present application, in the inter-subarray phase interferometer, the size design of the sparse uniform array can be as shown in the following formula 6-8:

[0105] d 0 =4λ; (Formula 6)

[0106] d 1 =0.5λ; (Formula 7)

[0107] d 2 =λ; (Formula 8)

[0108] The uniform sparse array corresponds to d 0 =4λ, to achieve an angular resolution of 1° (corresponding to 0.0175 rad), the number of unit antenna groups is n=14, as shown in formula 9. Figure 12-14 shown.

[0109]

[0110] Fig.12 The number of antennas in the uniform sparse array example shown is 14*3=42, which is only Figure 8 The number of antennas in the half-wavelength non-sparse uniform array example shown is 42 / 114=37%. The uniform sparse array significantly reduces the number of antennas and channels of the vehicle-mounted millimeter-wave radar. Fig.12 The sparse uniform array example shown may be a physical array formed by non-MIMO or a virtual array formed by MIMO; it may be a whole array or a partial sub-array in the whole array.

[0111] If it is a non-MIMO working mode, the typical example is that the transmitting array adopts the full array phased array synthesis working mode. Fig.12 The sparse uniform array shown represents the entire receiving array, or a portion of the receiving array. For example, if the non-MIMO working mode is used, the transmitting array and the receiving array of the sparse uniform array vehicle-mounted millimeter wave radar can be as follows: Fig.13 As shown, the topology of the transmit array does not affect the direction finding use of the receive array.

[0112] If it is MIMO working mode, Fig.12 The sparse uniform array shown represents the entire MIMO virtual receiving array, or is a part of the entire MIMO virtual receiving array. For example, if the MIMO working mode is, Fig.12 The transmitting array and receiving array of the vehicle-mounted millimeter-wave radar with sparse uniform array shown in FIG. Fig.14 shown.

[0113] The target angle measurement method of the sparse antenna array of the vehicle-mounted millimeter wave radar provided in the embodiment of the present application mainly comprises: Figure 2 The MRP millimeter wave radar processor shown in FIG. Fig. 9 and Fig.10 As shown, the following steps are included:

[0114] S11, obtaining information required for angle measurement through subarray T, subarray C and subarray S; the information required for angle measurement mainly includes relative amplitude information and relative phase information between antenna channels within subarray T, subarray C and subarray S.

[0115] S12, obtaining the angle spectra of the sub-array T, the sub-array C, and the sub-array S through FFT (Fast Fourier Transform) angle measurement operation or DBF (Digital Beam Forming) angle measurement operation.

[0116] S13, performing non-coherent accumulation on the angle spectra of sub-array T, sub-array C and sub-array S to obtain angle spectra for angle peak detection. The non-coherent accumulation can improve the sensitivity of angle peak detection.

[0117] S14, performing angle peak detection on the angle spectrum after non-coherent accumulation.

[0118] S15, combining the angles obtained by the angle peak detection to form a potential angle set, and according to the index of the potential angle set in the angle spectrum used for angle peak detection, respectively obtaining the angle FFT data of sub-array T, sub-array C and sub-array S corresponding to each potential angle in the potential angle set.

[0119] S16, using the angle FFT data of sub-arrays T, C and S corresponding to each potential angle, using the inter-sub-array phase interferometer TCS to perform angle measurement and deambiguation to determine the true target angle.

[0120] Due to the existence of grating lobes in the uniform sparse array, all the detected points after the peak detection of the angle spectrum after non-coherent accumulation will include real angle and false angle information. It is impossible to distinguish the real angle from the false angle based on the angle peak detection result alone. Based on the potential angle set formed by the real angle and the false angle, the inter-subarray phase interferometer TCS is used to perform angle measurement deambiguation calculation to eliminate the false angle and obtain the real incoming wave direction angle.

[0121] The typical workflow of the vehicle-mounted millimeter wave radar using the sparse antenna array and the angle measurement method thereof proposed in the embodiment of the present application is as follows: Fig.11 As shown, the following steps are included:

[0122] S211, vehicle-mounted millimeter-wave radar is powered on and initialized.

[0123] S212, the vehicle-mounted millimeter-wave radar receives an instruction to start working.

[0124] S221, the MRTR chip receives the waveform signal reflected by the target.

[0125] S222, the MRTR chip performs discrete ADC sampling on the waveform signal reflected by the received target.

[0126] S230, the MRP chip performs one-dimensional distance FFT processing on the discrete ADC signal from the MRTR chip.

[0127] S231, the MRP chip performs two-dimensional velocity FFT processing on the one-dimensional distance FFT processing result.

[0128] S232, the MRP chip performs CFAR constant false alarm detection on the two-dimensional velocity FFT processing result.

[0129] S233, the MRP chip uses sub-array T, sub-array C and sub-array S to perform angle-dimensional FFT processing on the over-detection points of the constant false alarm detection.

[0130] S234, the MRP chip performs non-coherent accumulation of the angle-dimensional FFT results of the sub-array T, the sub-array C, and the sub-array S.

[0131] S235, the MRP chip performs angle peak detection on the angle FFT result after non-coherent accumulation.

[0132] S236, according to the size parameters of the sparse antenna array, the MRP chip performs main lobe and grating lobe pairing on the angle peak detection result. Here, it should be noted that the main lobe and grating lobe pairing refers to an optional detection principle for angle peak detection, by screening the detected radiation intensity, finding the peak with the maximum radiation intensity and the intensity basically matching it as the main lobe and grating lobe pairing result, and determining all potential angles in turn to form a potential angle set.

[0133] S237, the MRP chip selects any angle from the pairing results of the main lobe and the grating lobe, that is, selects any potential angle from the potential angle set.

[0134] S238, the MRP chip uses the selected angle and index to obtain the angle-dimensional FFT results of sub-array T, sub-array C, and sub-array S.

[0135] S239, the MRP chip performs phase interferometer direction finding between sub-array T, sub-array C and sub-array S according to the size parameters between sub-array T, sub-array C and sub-array S and the angle dimension FFT result.

[0136] S240, obtaining an angle deviation between each angle in the current main lobe and grating lobe pairing and the direction finding angle of the inter-subarray phase interferometer.

[0137] S241, determine whether the angle deviation is less than a set threshold; if so, determine that the direction finding angle is valid, and use the direction finding angle of the inter-sub-array phase interferometer as the final direction finding result, otherwise return direction finding failure.

[0138] S242, cyclically completing the inter-subarray phase interferometer deambiguation of all main lobe and grating lobe pairing results.

[0139] S243, cyclically completing the direction finding processing of all CFAR constant false alarm check points.

[0140] S244, the MRP chip performs target clustering recognition and tracking, and performs target-level data processing.

[0141] S245, the MRP chip outputs point cloud-level detection results or target-level detection results.

[0142] S246, looping to complete scene target detection, outputting detection results, until the conditions for stopping work are met.

[0143] Among them, according to Fig.12 The sparse antenna array shown in FIG. 1 , the subarray T, subarray C and subarray S constitute the inter-subarray phase interferometer TCS as shown in FIG. Fig.15 shown.

[0144] Assumptions Fig.12 The target wave direction shown by the sparse antenna array in the figure is θ = 10°, then Fig.16 The angle spectra of the sub-arrays T, C and S shown in the figure are accumulated in a non-coherent manner. Fig.17 shown.

[0145] For example Fig.17 The angle spectrum shown in the figure is used to detect the angle peak and obtain Fig.17 The true angle 10° corresponding to the main lobe peak shown in the figure, and the false angles -55.8°, -35.2°, -19.1°, -4.4°, 25.1°, and 42.3° corresponding to the six grating lobe peaks, respectively, the main lobe angle and all grating lobe false angles form a potential angle set.

[0146] according to Fig.17 The index of each potential angle in the potential angle set shown is used to obtain the angle spectrum data of the potential angle in the sparse uniform subarray examples T, C, and S. For each sparse uniform subarray example T, C, and S in the same sparse uniform array, the angle spectrum of the potential angle set is the same.

[0147] Fig.12 The sparse antenna array shown receives the signal of the target wave direction θ = 10°, and the angle spectrum of the potential angle set in the sparse uniform subarray examples T, C, S satisfies the theoretical relationship shown in the following formulas 10 and 11:

[0148]

[0149] Among them, the uniform sub-array examples T, C, S are as follows Fig.15 As shown, A T represents the angle spectrum in the potential angle set matrix T, A C represents the angle spectrum of the potential angle set in the sub-matrix C, A S represents the angle spectrum of the potential angle set in the subarray S, and f represents the frequency of the transmitted and received waveform signals.

[0150] The angle spectrum relationship of the potential angle set in the sparse uniform subarray examples T, C, S satisfies Fig.16 The inter-subarray phase interferometer example TCS is shown. Based on the angle spectrum of the potential angle set in the sparse uniform subarray examples T, C, and S (as shown in the above formulas 1 and 2, the angle spectrum of the sparse uniform subarray examples T, C, and S can be respectively obtained by A T , A C , A S indicates) and Fig.16 The inter-subarray phase interferometer example TCS shown in the figure can select the known phase interferometer angle measurement algorithm to obtain the target's unique incoming wave direction θ = 10°, eliminating Fig.17 All the false angles of grating lobes are shown in the figure, so as to achieve high-resolution angle measurement of sparse antenna array and eliminate its false targets of grating lobes.

[0151] The vehicle-mounted millimeter-wave radar with sparse antenna array and angle measurement method thereof proposed in the above embodiment has at least the following characteristics:

[0152] First, in response to the low-cost, high-angle resolution direction-finding requirements of vehicle-mounted millimeter-wave radar, the sparse antenna array is split into multiple sub-arrays of a sparse uniform array, and each sub-array is used to receive the signal and process it to obtain the angle spectrum corresponding to each sub-array. Based on the angle spectrum corresponding to each sub-array, the angle spectrum for angle peak detection is obtained, and a potential angle set containing true angles and false angles is obtained. The inter-subarray phase interferometer angle measurement deambiguation method is then used to achieve low-resolution angle measurement and eliminate grating lobe false angles.

[0153] Second, it supports the angle deambiguation algorithm of the inter-subarray phase interferometer composed of 2 or more sub-arrays. The more sub-arrays there are, the longer the direction-finding baseline of the inter-subarray phase interferometer is, which can effectively improve the angle deambiguation accuracy and angle measurement accuracy, and improve the robustness of the angle measurement results to noise.

[0154] Third, high-resolution angle measurement of vehicle-mounted millimeter-wave radar is achieved based on sparse uniform array. The spacing between array aperture unit antennas can be much larger than half a wavelength, which can effectively reduce the number of transceiver channels and antennas of vehicle-mounted millimeter-wave radar with high angle measurement resolution, thereby effectively reducing the cost of vehicle-mounted millimeter-wave radar with high angle measurement resolution.

[0155] On the other hand, please refer to Figure 2 and Fig.18 , a vehicle-mounted millimeter wave radar is also provided, comprising a millimeter wave radar processor 201 and a memory 202. The memory 202 stores a computer program that can be executed by the millimeter wave radar processor 201; when the computer program is executed by the millimeter wave radar processor 201, the target angle measurement method of the sparse antenna array described in any embodiment of the present application is implemented.

[0156] Optionally, the vehicle-mounted millimeter-wave radar also includes an antenna array and a millimeter-wave radar transceiver module; the antenna array includes a transmitting antenna array and a receiving antenna array; the millimeter-wave radar transceiver module includes a transmitting component, a receiving component and a linear frequency modulation local oscillator source component.

[0157] Optionally, the antenna array used for angle measurement can be formed by a MIMO working mode, a non-MIMO working mode or other methods; and the antenna array used for angle measurement is a sparse antenna array formed by repeatedly arranging n unit antenna groups. Here, the antenna array used for angle measurement can be a physical array or a virtual array, and can be the entire array or a part of the sub-array in the antenna array, which has been mentioned in the description of the above embodiment and will not be repeated here.

[0158] On the other hand, embodiments of the present application further provide a computer program product, including a computer program, which, when executed by a processor, implements the target angle measurement method of the sparse antenna array of any embodiment of the present application.

[0159] On the other hand, the embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, each process of the target angle measurement method embodiment of the sparse antenna array is implemented, and the same technical effect can be achieved. To avoid repetition, it is not repeated here. The computer-readable storage medium is, for example, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0160] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0161] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0162] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for measuring target angles using a sparse antenna array, wherein the sparse antenna array comprises n unit antenna groups arranged repeatedly, wherein the unit antenna groups comprise m unit antennas, and the spacing between the unit antenna groups is not equal to the spacing between adjacent unit antennas in the unit antenna groups, wherein: The method comprises: Based on the unit antennas included in each unit antenna group in the sparse antenna array, determine the unit antenna subarrays corresponding to each of the unit antennas; wherein each of the unit antenna subarrays is composed of unit antennas with the same serial number in each of the unit antenna groups; Acquire signals respectively received by each of the unit antenna subarrays, process the signals to obtain first angle spectra corresponding to each of the unit antenna subarrays, and then perform non-coherent accumulation on the first angle spectra of each of the unit antenna subarrays to obtain second angle spectra; Performing angle peak detection on the second angle spectrum to obtain a potential angle set; The real target angle is determined from the potential angle set according to the angle spectrum data of the unit antenna subarray corresponding to each potential angle in the potential angle set.

2. The target angle measurement method of the sparse antenna array according to claim 1, characterized in that: Determining the true target angle from the potential angle set according to the angle spectrum data of the unit antenna subarray corresponding to each potential angle in the potential angle set includes: According to the angle spectrum data of the unit antenna subarray corresponding to each potential angle in the potential angle set, angle measurement deambiguation is performed using a phase interferometer angle measurement algorithm through a subarray phase interferometer formed by each unit antenna group, and the real target angle is determined from the potential angle set.

3. The target angle measurement method of the sparse antenna array according to claim 2, characterized in that: The unit antenna includes a first unit antenna T, a second unit antenna C and a third unit antenna S, and the unit antenna subarray includes a first unit antenna subarray composed of the first unit antenna T, a second unit antenna subarray composed of the second unit antenna C and a third unit antenna subarray composed of the third unit antenna S; according to the angle spectrum data of the unit antenna subarrays corresponding to each potential angle in the potential angle set, the phase interferometer between subarrays composed of each unit antenna group uses a phase interferometer angle measurement algorithm to perform angle measurement deambiguation, and determine the real target angle from the potential angle set, including: According to the angle spectrum data A of the first unit antenna subarray corresponding to each potential angle in the potential angle set T , the angle spectrum data A of the second unit antenna subarray C and the angle spectrum data A of the third unit antenna subarray S ; The phase interferometer between the sub-arrays formed by each of the unit antenna groups is used to perform angle measurement deambiguation using a phase interferometer angle measurement algorithm, and the angle spectrum data A corresponding to the potential angles are respectively T , A C , A S Whether the phase interference relationship is satisfied to determine the actual target angle from the potential angle set.

4. The target angle measurement method of the sparse antenna array according to claim 3, characterized in that: The phase interference relationship is as follows: Wherein, f represents the frequency of transmitting and receiving waveform signals, λ represents the wavelength of the transmitted waveform signal, d1 is the distance between the first unit antenna T and the second unit antenna C in the unit antenna group, and d2 is the distance between the second unit antenna T and the third unit antenna S in the unit antenna group.

5. The target angle measurement method of the sparse antenna array according to claim 4, characterized in that: The d1 and d2 respectively satisfy the following relationship: Where 0<θ max ≤90°.

6. The target angle measurement method of a sparse antenna array according to claim 4, characterized in that: The d1 is 0.5λ, and the d2 is λ.

7. The target angle measurement method of a sparse antenna array according to claim 4, characterized in that: In the unit antenna subarray, the distance between adjacent unit antennas is d0, and d0 is 4λ.

8. The target angle measurement method of a sparse antenna array according to claim 1, characterized in that: The acquiring of signals respectively received by each of the unit antenna subarrays, processing the signals to obtain first angle spectra corresponding to each of the unit antenna subarrays, and then performing non-coherent accumulation on the first angle spectra of each of the unit antenna subarrays to obtain a second angle spectrum includes: The discrete digital signal obtained by performing discrete digital signal sampling processing on the received waveform signal reflected by the target is subjected to one-dimensional distance FFT processing to obtain a one-dimensional distance FFT result; Performing two-dimensional velocity FFT processing on the one-dimensional distance FFT result to obtain a two-dimensional velocity FFT result; Performing constant false alarm detection on the two-dimensional velocity FFT result to obtain check point data; Use each of the unit antenna subarrays to perform angle-dimensional FFT processing on the check point data to obtain a first angle spectrum corresponding to each of the unit antenna subarrays, and perform non-coherent accumulation on the first angle spectrum to obtain a second angle spectrum.

9. The target angle measurement method of a sparse antenna array according to claim 8, characterized in that: Determining the true target angle from the potential angle set according to the angle spectrum data of the unit antenna subarray corresponding to each potential angle in the potential angle set includes: Select any potential angle in the potential angle set, and obtain the angle dimension FFT result of the corresponding unit antenna subarray; According to the size parameters of the inter-sub-array phase interferometer formed by each of the unit antenna groups and the angle-dimensional FFT result, the inter-sub-array phase interferometer is directionally measured; Obtaining an angle deviation between a potential angle and a direction-finding angle of the inter-sub-array phase interferometer; Determining whether the angle deviation is less than a set threshold; If the angle deviation is less than the set threshold, the current direction finding result of the inter-sub-array phase interferometer is taken as a qualified direction finding result; The angle measurement deambiguation of all potential angles is completed in a loop, and the true target angle is determined from the potential angle set.

10. A vehicle-mounted millimeter wave radar, characterized in that: The invention comprises a millimeter wave radar processor and a memory, wherein the memory stores a computer program executable by the millimeter wave radar processor; When the computer program is executed by the millimeter wave radar processor, the target angle measurement method of the sparse antenna array according to any one of claims 1 to 9 is implemented; The antenna array used for angle measurement is formed by a MIMO working mode or a non-MIMO working mode.

11. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the target angle measurement method of the sparse antenna array according to any one of claims 1 to 9 is implemented.

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