A sparse array formation and angular resolution optimization method for 77GHz automotive radar

Abstract

The present invention relates to a sparse array configuration and angular resolution optimization method for a 77GHz automotive radar. The sparse array is composed of multiple transmitting antennas and multiple receiving antennas; the sum of the spacings between the multiple transmitting antennas is twice the sum of the spacings between the multiple receiving antennas, and in a virtual array element formed by the multiple receiving antennas, the subarray spacing is equal to the sum of the spacings between the multiple receiving antennas; and the spacings between adjacent receiving antennas, when arranged from small to large, form a geometric progression. The present invention constructs a virtual array with equally spaced subarrays and low grating lobes by specifying the spacings between the transmitting and receiving antennas. By comparing the beamforming results of the windowed subarrays and the sparse array, the effects of sidelobes and grating lobes on the angular measurement of the 77GHz automotive radar are effectively reduced. The constructed sparse array improves the angular resolution performance of the 77GHz automotive radar, while also reducing interference from grating lobes and sidelobes, thereby improving the performance of the 77GHz automotive radar.

Description

Technical Field

[0001] The present invention relates to the technical field of array antenna design, and more particularly to a sparse array formation and angular resolution optimization method for a 77 GHz automotive radar. Background Art

[0002] ADAS and autonomous driving are placing higher demands on various millimeter-wave radar sensor specifications, such as angular resolution and angle measurement accuracy. To further improve wireless communication transmission rates and radar resolution, the 77 / 79 GHz frequency band is becoming the primary development direction for automotive collision avoidance radar.

[0003] To ensure the accuracy of radar detection, it is necessary to minimize the impact of various interference factors, and grating lobes are one of the most influential factors. Since the generation of grating lobes and side lobes is closely related to the design of the radar itself, when there are high requirements for radar resolution, the aperture of the radar antenna array needs to be increased to improve the accuracy of azimuth estimation. The most intuitive implementation method is to set the array element spacing according to the upper limit of the frequency band of the processed signal, and increase the array aperture by directly increasing the number of array elements. However, this large-area dense array element arrangement method is too expensive and often difficult to implement. To reduce the manufacturing cost and complexity of the antenna array, a sparsely arranged antenna unit design can only be adopted. By reducing the number of array elements and channels, a smaller number of array elements is required to achieve a larger array aperture, achieving the desired array performance at a lower cost.

[0004] At present, due to the limitation of the limited number of channels, the existing sparse array will produce grating lobes and high side lobes. In order to further improve the angular resolution performance of the radar, it is necessary to further optimize the sparse array to reduce the interference of grating lobes and side lobes on the radar, thereby improving the accuracy of radar angle measurement. Summary of the Invention

[0005] To overcome the problem that the sparse array used in existing 77GHz automotive radars to achieve ultra-high angular resolution is difficult to eliminate, resulting in interference with the angular resolution performance of the 77GHz automotive radar, the present invention provides a sparse array formation and angular resolution optimization method for a 77GHz automotive radar.

[0006] A sparse array configuration for a 77GHz automotive radar is constructed using multiple transmitting antennas and multiple receiving antennas. The sum of the spacing between the transmitting antennas is twice the sum of the spacing between the receiving antennas, and within a virtual array element formed by the receiving antennas, the subarray spacing is equal to the sum of the spacing between the receiving antennas. The spacing between adjacent receiving antennas, when arranged from smallest to largest, forms a geometric progression. The present invention creates a sparse array by arranging transmitting and receiving antennas at specific spacings. This array exhibits low grating lobes, thereby reducing their impact on the angular resolution performance of the automotive radar.

[0007] Furthermore, as a preferred technical solution, the number of the transmitting antennas is 3, and the number of the receiving antennas is 4. Therefore, the antennas used in the automotive radar of the present application are three transmitting and four receiving antennas.

[0008] Furthermore, as a preferred technical solution, the spacing between two adjacent receiving antennas conforms to the relationship between 1, 2, and 4 half-wavelengths. The spacing between the receiving antennas uses this determined data, so that the spacing between multiple receiving antennas can be determined, making the designed antenna more accurate.

[0009] Furthermore, as a preferred technical solution, the spacing between the middle transmitting antenna and the two middle receiving antennas is adjusted based on the sparse array sidelobe level. The spacing between the middle transmitting antenna and the two middle receiving antennas is adjusted based on the sparse array sidelobe level, and the positions of the middle transmitting antenna and the two middle receiving antennas corresponding to the lowest sparse array sidelobe level are set as the optimal design, thereby minimizing the sparse array sidelobe level.

[0010] Furthermore, as a preferred technical solution, the subarray of the virtual array element is a uniform array. The subarray is divided from the virtual array element, and the subarray divided from the virtual array element constructed by using the transmitting antenna and receiving antenna with the above-mentioned spacing is a uniformly spaced subarray.

[0011] Furthermore, as a preferred technical solution, the number of the virtual array elements is 12. The number of the virtual array elements is determined by the number of transmitting antennas, the number of receiving antennas, and the spacing between the transmitting antennas and the receiving antennas.

[0012] A method for optimizing angular resolution of a 77 GHz automotive radar comprises the following steps:

[0013] A sparse array is constructed; the sparse array is a sparse array type for 77GHz automotive radar, that is, it is constructed by designing specific spacing between transmitting antennas and receiving antennas, and the constructed sparse array has equally spaced sub-arrays and low grating lobes.

[0014] The sub-arrays of the sparse array are subjected to windowing processing to remove the influence of the side lobes on the sub-arrays. Through this step, only the grating lobes remain in the sub-arrays of the sparse array.

[0015] Obtain the beamforming results of the windowed sub-array and sparse array respectively; this step can be used to determine the target position in the next step.

[0016] Whether the target is in the main lobe is determined based on the beamforming results of the sub-array and sparse array.

[0017] Furthermore, as a preferred technical solution, the sub-array is a uniform array, and the window added to the sub-array includes a Taylor window, a Chebyshev window or a Hamming window.

[0018] Furthermore, as a preferred technical solution, performing windowing processing on the sub-matrix of the sparse array specifically includes:

[0019] For uniform arrays, a Taylor window is directly added to the amplitude; or, a Chebyshev window is directly added to the amplitude; or, a Hamming window is directly added to the amplitude.

[0020] Furthermore, as an optimal technical solution, the grating lobe corresponding to the sparse array is lower than the main lobe.

[0021] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0022] The present invention constructs a virtual array with equally spaced subarrays and low grating lobes by specifying the spacing between transmitting and receiving antennas. By comparing the beamforming results of the windowed subarrays and a sparse array, the influence of sidelobes and grating lobes on the angle measurement of a 77GHz automotive radar is effectively improved. The constructed sparse array improves the angular resolution performance of the 77GHz automotive radar, while also reducing the interference of grating lobes and sidelobes, thereby improving the performance of the 77GHz automotive radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the spacing between transmitting antennas in Example 1 of the present invention.

[0024] Figure 2 Schematic diagram of the spacing between receiving antennas in embodiment 1 of the present invention.

[0025] Figure 3 Schematic diagram of the distribution of virtual array elements constructed in Example 1 of the present invention.

[0026] Figure 4 Schematic diagram of the distribution of sub-arrays divided from virtual array elements in embodiment 1 of the present invention.

[0027] Figure 5 This is a simulation diagram of beamforming performed at 0° by equally spaced subarrays according to Example 1 of the present invention.

[0028] Figure 6 This is a simulation diagram of the equally spaced subarrays after beamforming and windowing at 0° in Example 1 of the present invention.

[0029] Figure 7 This is a simulation diagram of the virtual array element after beamforming at 0° in Example 1 of the present invention.

[0030] Figure 8 This is a flow chart of the angular resolution optimization method for a 277 GHz automotive radar according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to specific embodiments.

[0032] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting this patent.

[0033] In addition, if terms such as "first" and "second" are used for descriptive purposes only, they are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components, and cannot be understood as indicating or implying relative importance.

[0034] Example 1

[0035] This embodiment discloses a sparse array for 77GHz automotive radar, such as Figure 2 As shown, it is composed of multiple transmitting antennas and multiple receiving antennas; the sum of the spacings between the multiple transmitting antennas is twice the sum of the spacings between the multiple receiving antennas, and in a virtual array element composed of the multiple receiving antennas, the sub-array spacing is equal to the sum of the spacings between the multiple receiving antennas; the spacings between adjacent receiving antennas form a geometric progression when arranged from small to large.

[0036] This embodiment constructs a sparse array by setting transmitting antennas and receiving antennas at specific intervals. The constructed sparse array has low grating lobes, thereby reducing the impact of grating lobes on the angular resolution performance of the automobile radar.

[0037] In this embodiment, the number of transmitting antennas is 3 and the number of receiving antennas is 4. Therefore, the antennas used by the automotive radar in this embodiment are three transmitting and four receiving antennas.

[0038] This embodiment is a preferred embodiment. The spacing between the three transmitting antennas is as follows: Figure 1 , the sum of the spacing between the three transmitting antennas from left to right is 7λ, and their wavelength is the wavelength corresponding to the working center frequency.

[0039] In this embodiment, the distance between two adjacent receiving antennas conforms to the relationship between 1, 2, and 4 times of a half wavelength.

[0040] This embodiment is a preferred embodiment. The spacing between the four receiving antennas is as shown in Figure 2 , the sum of the spacings between the four receiving antennas from left to right is 3.5λ, that is, the sum of the spacings between multiple transmitting antennas is twice the sum of the spacings between multiple receiving antennas.

[0041] Also, see Figure 3 It can be seen that the spacing between the four receiving antennas is 0.5λ, 1λ, and 2λ from left to right, respectively, which conforms to the design rule that the spacing between two adjacent receiving antennas forms a geometric progression when arranged from small to large.

[0042] In some embodiments, the spacing between the four receiving antennas from left to right can be 1λ, 0.5λ, or 2λ, or the spacing between the four receiving antennas from left to right can be 2λ, 1λ, 0.5λ, or any other arrangement, as long as the spacing between adjacent receiving antennas conforms to the design rule that the spacing between adjacent receiving antennas forms a geometric progression when arranged from smallest to largest. Furthermore, the sum of the spacing between the four receiving antennas and the sum of the spacing between the three transmitting antennas meet the design requirement that the sum of the spacing between the multiple transmitting antennas is twice the sum of the spacing between the multiple receiving antennas.

[0043] Therefore, in this embodiment, the spacing between the receiving antennas adopts the determined data, so that the sum of the spacings between multiple receiving antennas can be determined, and the sum of the spacings between multiple transmitting antennas can be further determined, so that the designed antennas are more accurate and the sparse array constructed is further more accurate.

[0044] In addition, since the sum of the spacings between the three transmitting antennas is twice the sum of the spacings between the four receiving antennas, the spacings between the transmitting antenna in the middle and the two receiving antennas in the middle are adjusted according to the sparse array sidelobe levels.

[0045] That is, the spacing between the middle transmitting antenna and the two middle receiving antennas is adjusted according to the sparse array sidelobe level, and the positions of the middle transmitting antenna and the two middle receiving antennas corresponding to the lowest sparse array sidelobe level are set to the optimal design, thereby minimizing the sparse array sidelobe.

[0046] That is, in the virtual array element of this embodiment, the positions of the three transmitting antennas and the four receiving antennas make the final sparse array sidelobe level the lowest.

[0047] Meanwhile, in this embodiment, since the sub-arrays are separated from the virtual array elements, the sub-arrays separated from the virtual array elements constructed by using the transmitting antennas and receiving antennas with the above-mentioned spacing are equally spaced sub-arrays, that is, the sub-arrays are uniform arrays.

[0048] In addition, since the number of the virtual array elements is determined by the number of transmitting antennas, the number of receiving antennas, and the spacing relationship between the transmitting antennas and the receiving antennas, the number of the virtual array elements is 12.

[0049] The distribution diagram of the 12 virtual array elements constructed by the three transmitting antennas and the four receiving antennas can be found in Figure 4 , where 4 array elements can be separated into equally spaced subarrays. The spacing between adjacent subarrays is 3.5λ, which is the same as the spacing between the four receiving antennas. Figure 5 , represented by shading; in addition, in the schematic diagram of the distribution of the 12 virtual array elements, the black background represents the 4 array elements corresponding to the first transmitting antenna, the gray background represents the 4 array elements corresponding to the second transmitting antenna, and the white background represents the 4 array elements corresponding to the third transmitting antenna.

[0050] Example 2

[0051] This embodiment discloses a method for optimizing the angular resolution of a 77 GHz automotive radar. Figure 7 As shown, the method includes the following steps:

[0052] S10. Construct the sparse array described in Example 1.

[0053] In this step, the sparse array is formed by 3 transmitting antennas and 4 receiving antennas; the sum of the spacings between the 3 transmitting antennas is twice the sum of the spacings between the 4 receiving antennas, and in the virtual array element formed by the 4 receiving antennas, the subarray spacing is equal to the sum of the spacings between the 4 receiving antennas; and the spacings between adjacent receiving antennas form a geometric progression when arranged from small to large.

[0054] The spacing between the three transmitting antennas and the spacing between the four receiving antennas are set as described in Example 1, and will not be described in detail in this embodiment.

[0055] The sparse array constructed in step 4 includes 12 virtual array elements, which can be divided into four equally spaced subarrays. The spacing between adjacent subarrays is equal to the spacing between the four receiving antennas. This sparse array also has low grating lobes.

[0056] S20. Perform windowing processing on the sub-array of the sparse array to remove the influence of side lobes on the sub-array.

[0057] In this step, the sub-arrays of the sparse array are equally spaced sub-arrays, that is, uniform arrays; and the windows added to the sub-arrays include any classical windows such as Taylor window, Chebyshev window or Hamming window.

[0058] Therefore, this step is specifically as follows: directly applying a Taylor window to the amplitude of the uniform array; or directly applying a Chebyshev window to the amplitude of the uniform array; or directly applying a Hamming window to the amplitude of the uniform array.

[0059] Through this step, the influence of the side lobes of the sub-array of the sparse array is eliminated, and the side lobes are reduced to a required range, so that only the grating lobes are left.

[0060] For details, see Figure 5 and Figure 6 , before windowing the equally spaced sub-arrays of the sparse array, the simulation diagram of beamforming at 0° by the equally spaced sub-arrays is shown in Fig. Figure 5 As shown in the figure, the grating lobe of the sparse array is as high as the main lobe, while the side lobe reaches about -11dB; after the sparse array's equally spaced sub-arrays are windowed, the equally spaced sub-arrays perform beamforming at 0°, see the simulation diagram. Figure 6 As shown, the grating lobe is as high as the main lobe, and the side lobe is easily suppressed to below -30dB.

[0061] S30. Obtain the beamforming results of the windowed sub-array and the sparse array respectively.

[0062] In this step, see Figure 6 After windowing the equally spaced sub-arrays of the sparse array, the grating lobe and the main lobe are at the same height in the simulation diagram of the equally spaced sub-arrays at 0° beamforming. The simulation diagram of the 12 virtual array elements at 0° beamforming is shown in Figure 2. Figure 7 As shown in the figure, the highest points of the grating lobe and side lobe are 8dB lower than the main lobe.

[0063] S40. Determine whether the target is in the main lobe based on the beamforming results of the sub-array and the sparse array.

[0064] The grating lobe corresponding to the sparse array is lower than the main lobe.

[0065] by Figure 6 and Figure 7 For example, these two figures are the results of 0° beamforming for the equally spaced subarray and the sparse array after windowing. In the spaced subarray, except for the 0° main lobe, the grating lobes at other positions have equal amplitudes, but there are no side lobes within -30dB. In the sparse array, except for the 0° main lobe, there are no equal-height grating lobes, that is, the grating lobe is lower than the main lobe by 8dB, but there are side lobes within -10dB. By comparing the two figures, it is found that the peak of both figures is the largest only at the 0° position, so the target appears in the 0° main lobe. The same is true for other target angles. Beamforming at other angles can be performed and the two figures can be compared.

[0066] The present invention constructs a virtual array with equally spaced subarrays and low grating lobes by specifying the spacing between transmitting and receiving antennas. By comparing the beamforming results of the windowed subarrays and a sparse array, the influence of sidelobes and grating lobes on the angle measurement of a 77GHz automotive radar is effectively improved. The constructed sparse array improves the angular resolution performance of the 77GHz automotive radar, while also reducing the interference of grating lobes and sidelobes, thereby improving the performance of the 77GHz automotive radar.

[0067] Example 3

[0068] This embodiment discloses a 77 GHz automotive radar device, comprising three transmitting antennas and four receiving antennas. The three transmitting antennas and the four receiving antennas are designed to have the specific spacing described in Example 1, thereby constructing the equally spaced subarrays and the sparse array with low grating lobes described in Example 1. The sparse array constructed by the radar device is then optimized for angular resolution using the method described in Example 2, thereby improving the angular resolution performance of the radar device and reducing interference from grating lobes and side lobes caused by the sparse array, further improving the performance of the radar device.

[0069] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A sparse array for 77GHz automotive radar, characterized in that: The array is composed of multiple transmitting antennas and multiple receiving antennas; the sum of the spacings between the multiple transmitting antennas is twice the sum of the spacings between the multiple receiving antennas, and in a virtual array element formed by the multiple receiving antennas, the sub-array spacing is equal to the sum of the spacings between the multiple receiving antennas; and the spacings between adjacent receiving antennas form a geometric progression when arranged from small to large. The number of the transmitting antennas is 3, and the number of the receiving antennas is 4; The distance between two adjacent receiving antennas conforms to the relationship between 1, 2, and 4 times half the wavelength.

2. The sparse array configuration for 77 GHz automotive radar according to claim 1, characterized in that: The spacing between the transmitting antenna located in the middle and the two receiving antennas located in the middle is adjusted according to the sparse array sidelobe level.

3. The sparse array configuration for 77 GHz automotive radar according to claim 1, characterized in that: The sub-array of the virtual array elements is a uniform array.

4. The sparse array configuration for 77 GHz automotive radar according to claim 1, characterized in that: The number of the virtual array elements is 12.

5. A method for optimizing angular resolution of a 77 GHz automotive radar, characterized in that: The following steps are involved: Constructing the sparse array according to any one of claims 1 to 4; Perform windowing on the sub-arrays of the sparse array to remove the influence of side lobes on the sub-arrays; Obtain the beamforming results of the windowed sub-array and sparse array respectively; Whether the target is in the main lobe is determined based on the beamforming results of the sub-array and sparse array.

6. The angular resolution optimization method for a 77 GHz automotive radar according to claim 5, characterized in that: The sub-array is a uniform array, and the window function used when performing windowing processing on the sub-array includes a Taylor window, a Chebyshev window or a Hamming window.

7. The angular resolution optimization method for a 77 GHz automotive radar according to claim 6, characterized in that: The windowing process for the sub-matrix of the sparse matrix specifically includes: For uniform arrays, a Taylor window is directly added to the amplitude; or, a Chebyshev window is directly added to the amplitude; or, a Hamming window is directly added to the amplitude.

8. The angular resolution optimization method for a 77 GHz automotive radar according to claim 5, characterized in that: The grating lobe corresponding to the sparse array is lower than the main lobe.

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