A two-dimensional array fast angle estimation method

Abstract

The application discloses a two-dimensional array fast angle estimation method, for an imaging radar with N transmitting and M receiving, a two-dimensional angle measurement array is formed through a MIMO channel, the horizontal two-dimensional angle measurement range is ±θ, the pitch is an angle interval, and the horizontal angle and the pitch angle of the two-dimensional angle estimation are limited in the horizontal ±θ and the pitch, respectively, a virtual antenna array with the largest horizontal array aperture is selected as an array main shaft, and the target horizontal angle θ is obtained through angle estimation of the array main shaft b and the maximum horizontal angle deviation θ μ , θ b ±θ μ is input as a prior value to perform two-dimensional angle estimation to obtain the horizontal and pitch angles of the real target. The application reduces the algorithm complexity and improves the calculation speed.

Description

Technical Field

[0001] This invention relates to the field of millimeter-wave radar technology, and in particular to a fast angle estimation method for a high-resolution two-dimensional array. Background Technology

[0002] Current automotive radar suffers from low angular resolution, and its imaging capabilities are insufficient for the needs of autonomous driving. For example, Tesla crashed into two vehicles crossing the road in Florida. This necessitates the continued use of lidar in current high-level autonomous driving systems. However, lidar suffers from insufficient environmental adaptability and difficulty meeting automotive-grade requirements, limiting the development and application of autonomous driving technology. Level 3 and higher autonomous driving systems demand high angular resolution capabilities in both azimuth and elevation from radar sensors, similar to the point cloud target output capabilities of lidar.

[0003] The statements herein provide only background information in relation to the present invention and do not necessarily constitute prior art. Summary of the Invention

[0004] The purpose of this invention is to provide a fast angle estimation method for two-dimensional arrays, which reduces algorithm complexity and improves computation speed.

[0005] To achieve the above objectives, this invention provides a fast angle estimation method for a two-dimensional array. For an imaging radar with N transmitters and M receivers, a two-dimensional angle measurement array is formed after virtualization via MIMO channels. The two-dimensional angle measurement range is ±θ horizontally and ±θ vertically. The angle measurement intervals are Δθ and Δθ. By designing the antenna, the horizontal and elevation angles of the two-dimensional angle estimation are limited to ±θ for horizontal and ±θ for elevation, respectively. Within the array, a virtual antenna array occupying the largest horizontal aperture is selected as the array's main axis. The target's horizontal angle θ is obtained by estimating the angle through the array's main axis. b and the maximum horizontal angle deviation θ μ , θ b ±θ μ Using these as prior values ​​as input, two-dimensional angle estimation is performed to obtain the horizontal and pitch angles of the true target.

[0006] The positions of the channel units that form the two-dimensional angle measuring array after being virtualized by the MIMO channel are denoted as:

[0007]

[0008] X mn and Z mn These represent the horizontal and vertical coordinates of the virtual channel unit formed by the transmitter m and receiver n on the array, respectively.

[0009] Then located in space The position target's echo path difference normalized amplitude and phase in the channel is denoted as:

[0010] Where, θ a It's a horizontal angle. It is the pitch angle.

[0011] The number of channels on the array's main axis is denoted as Q, then it is located in space. The normalized amplitude-phase return path difference of the target position in the main axis channel is denoted as:

[0012]

[0013] Use the array principal axis to estimate the azimuth angle of the target:

[0014] Assuming the pitch angle is 0°, the phase compensation formula is used. A steering vector table is generated, and digital beamforming is performed on the echo signals from the main spindle array to obtain: Find the modulus The θ corresponding to the maximum value k The value, denoted as θ b .

[0015] [θ] b -θ μ θ b +θ μ Using the angle values ​​within the specified range as prior values, the phase compensation formula is applied. A steering vector table is generated, and digital beamforming is performed on the echo signals of all two-dimensional array channels to obtain:

[0016] Find the modulus The maximum value corresponding to The value is the two-dimensional angle of the target in space.

[0017] This invention reduces algorithm complexity and improves computation speed. Attached Figure Description

[0018] Figure 1 This is a receiving antenna channel arrangement according to an embodiment of the present invention.

[0019] Figure 2 This is one method of arranging transmitting antenna channels according to an embodiment of the present invention.

[0020] Figure 3This is an embodiment of the present invention that forms an antenna channel arrangement after MIMO virtualization.

[0021] Figure 4 This is a spindle array selected by the antenna channel arrangement method after MIMO virtualization in an embodiment of the present invention. Detailed Implementation

[0022] The following is based on Figures 1-4 The preferred embodiments of the present invention will be described in detail below.

[0023] Millimeter-wave radar is an indispensable key component of Advanced Driver Assistance Systems (ADAS). During vehicle operation, it detects surrounding motor vehicles, non-motorized vehicles, pedestrians, and relevant road conditions to acquire information such as the distance, speed, orientation, and angle of nearby objects, providing data for ADAS system decision-making. Its strong all-weather capability is a particularly valuable advantage, unmatched by light-sensing sensors such as lasers and video sensors. Therefore, it plays an irreplaceable role in ADAS systems and future autonomous driving.

[0024] 4D millimeter-wave imaging radar can be applied to vehicle-side intelligent driving and roadside smart transportation. Its main functions are to reconstruct the three-dimensional geometric and motion information of the environment and target in real time with high precision, establish the relative spatial position relationship and relative motion speed between the radar placement point and the target, construct vehicle operation scenarios, and provide rich road scene information for vehicle-side and roadside, supporting high-level autonomous driving and high-level smart road construction.

[0025] This invention provides a fast angle estimation method for a two-dimensional array. For an imaging radar with M transmitting and N receiving arrays, a two-dimensional angle measurement array is formed after virtualization via MIMO channels. The two-dimensional angle measurement range is ±θ horizontally and ±θ vertically. The angle measurement intervals are Δθ and Δθ. The algorithm complexity for estimating the angle of a two-dimensional array is then...

[0026] By designing the antenna, the horizontal and elevation angles of the two-dimensional angle estimation are limited to ±θ for horizontal and ±θ for elevation, respectively. Range (spatial coverage area of ​​millimeter-wave radar).

[0027] The channel cell positions of the two-dimensional angle measuring array formed after MIMO channel virtualization are denoted as follows: X mn and Z mn Let m and n represent the horizontal and vertical coordinates of the virtual channel unit formed by the transmitter and receiver respectively on the array. Then, the spatial coordinates are... The position target's echo path difference normalized amplitude and phase in the channel is denoted as:

[0028]

[0029] Where, θ a It's a horizontal angle. It is the pitch angle.

[0030] The virtual antenna array occupying the largest horizontal aperture is selected as the array's main axis, and the number of channels on this main axis is denoted as Q. Then, the array located in space... The normalized amplitude-phase return path difference of the target position in the main axis channel is denoted as:

[0031] The target's azimuth angle is estimated using the array's main axis, assuming the elevation angle is 0°, and the phase compensation formula is used. A steering vector table is generated, and digital beamforming is performed on the echo signals from the main spindle array to obtain:

[0032] Find the modulus The θ corresponding to the maximum value k The value, denoted as θ b .

[0033] For the aforementioned virtual antenna array, azimuth angle estimation is performed using the selected array principal axis under the assumption that the elevation angle is 0°. This method introduces different magnitudes of horizontal angle deviation at different horizontal and elevation angles. An angle-by-angle simulation analysis is performed on the virtual antenna array and the selected array principal axis within a two-dimensional angular measurement range to determine the maximum horizontal angle deviation θ. μ Record this as the maximum possible deviation of the array.

[0034] The target horizontal angle θ is obtained by angle estimation through the array principal axis. b Add the maximum possible deviation θ μ , will [θ b -θ μ θ b +θ μ Using the angle values ​​within the specified range as prior values, the phase compensation formula is applied.

[0035] A steering vector table is generated, and digital beamforming is performed on the echo signals of all two-dimensional array channels to obtain:

[0036] Find the modulus The θ corresponding to the maximum value i , The value is the two-dimensional angle of the target in space.

[0037] The complexity of this fast 2D angle estimation algorithm is . Therefore, the time complexity of this two-dimensional angle fast estimation algorithm is that of not performing two-dimensional fast angle estimation. times.

[0038] Example

[0039] In one embodiment of the present invention, taking a 6-transmit, 8-receive imaging radar system as an example, M=6, N=8, the horizontal beamwidth is ±55° and the elevation beamwidth is ±9° with a 6dB beamwidth for the transmit and receive antennas, and the angular measurement range is constrained to ±55° horizontally and ±9° vertically with a 12dB suppression for both transmit and receive routes. Taking a 77GHz radar system as an example, the wavelength λ=3.896mm, and the receiver array is arranged as follows... Figure 1 As shown, the receiving antenna channel has a horizontal dx = 2.3781 mm and no elevation distribution. The transmitting array is as follows. Figure 2 As shown, the horizontal dx of the transmitting antenna channel is 2.3781 mm, and the elevation dz is 12.4525 mm.

[0040] For an imaging radar with M transmitting arrays and N receiving arrays, the two-dimensional angle measuring array formed after MIMO channel virtualization is as follows: Figure 3 As shown, the horizontal angle measurement interval is Δθ = 0.1° and The algorithm complexity for estimating the angle of a two-dimensional array is 9565488.

[0041] The channel cell positions of the two-dimensional angle measuring array formed after MIMO channel virtualization are denoted as follows:

[0042] Suppose a target is located at (21°, 4.5°) in space. The normalized amplitude and phase of the target's echo path difference in the channel are denoted as:

[0043] like Figure 4 As shown, a virtual antenna array occupying the largest horizontal array aperture is selected as the array's main axis. This main axis has 36 channels, and the position of each channel is E. Q =|(X0, Z0), (X1, Z1)…(X q Z q)|=|(0,0),(dx,0),(2dx,0),(3dx,0),(4dx,0),(5dx,0),(6dx,0),(7dx,0),(8dx,0),(9dx,0),(10dx,0),(11dx, 0), (12dx, 0), (13dx, 0), (14dx, 0), (15dx, 0), (16dx, 0), (17dx, 0), (18dx, 0), (19dx, 0), (20dx, 0), (21dx, 0), (22d x, 0), (23dx, 0), (24dx, dz), (25dx, dz), (26dx, dz), (27dx, dz), (28dx, 2dz), (29dx, 2dz), (30dx, 2dz), (31dx, 2dz), (32dx, 3dz), (33dx, 3dz), (34dx, 3dz), (35dx, 3dz)|, q=0, 1, ...35, the echo path difference normalized amplitude and phase of the target located at position (21°, 4.5°) in space on the main axis channel is denoted as:

[0044] The target's azimuth angle is estimated using the array's main axis, assuming the elevation angle is 0°, and the phase compensation formula is used. Generate a steering vector table and perform digital beamforming on the array spindle echo signal. Find the θ corresponding to the maximum value of |F1(21°, 4.5°)|. k The value is 23.4°.

[0045] For the virtual antenna array mentioned above, the azimuth angle is estimated using the selected array main axis under the assumption that the elevation angle is 0°. An angle-by-angle simulation analysis is performed on the virtual antenna array and the selected array main axis within the two-dimensional angle measurement range. The maximum possible deviation of the array is 4.5°.

[0046] The target horizontal angle of 23.4°, obtained by angle estimation through the array principal axis, is factored with a probability bias of 4.5°. Angle values ​​within the range of [18.9°, 27.9°] are used as prior values, and the phase compensation formula is applied. Generate a steering vector table and perform digital beamforming on the echo signals of all two-dimensional array channels to obtain:

[0047] Find the θ corresponding to the maximum value of F2|(21°, 4.5°)|. i , The values ​​are 21° and 4.5°, respectively.

[0048] The complexity of this fast 2D angle estimation algorithm is . The complexity of this two-dimensional angle fast estimation algorithm is 0.0868 times that of the algorithm without two-dimensional fast angle estimation, which means that the two-dimensional angle fast estimation algorithm can be improved by 11.5207 times in this specific embodiment.

[0049] It should be noted that, for ease of description, this invention is described using only a single target at the same distance and speed. This method is also applicable to multi-target scenarios at the same distance and speed, and should be understood and known by those skilled in the art.

[0050] It should be noted that, in the embodiments of the present invention, the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the embodiments. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0051] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0052] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A fast angle estimation method for a two-dimensional array, characterized in that, For an imaging radar with M transmitting antennas and N receiving antennas, a two-dimensional angle measuring array is formed after virtualization via MIMO channels. The horizontal range of the two-dimensional angle measuring array is... and up and down The angle measurement intervals are respectively and Through antenna design, the horizontal and elevation angles of the two-dimensional angle estimation are respectively limited to the horizontal. and up and down Within the array, a virtual antenna array occupying the largest horizontal aperture is selected as the array's main axis. The target's horizontal angle is then estimated using this main axis. and maximum horizontal angle deviation ,Will Using the prior values ​​as input, two-dimensional angle estimation is performed to obtain the horizontal and pitch angles of the true target; The positions of the channel units that form the two-dimensional angle measuring array after being virtualized by the MIMO channel are denoted as: ， ； and These represent the horizontal and vertical coordinates of the channel element virtually formed by the transmitting antenna m and the receiving antenna n on the array, respectively. Then located in space The position target's echo path difference normalized amplitude and phase in the channel is denoted as: ,in, It's a horizontal angle. It is the pitch angle; The number of channels of the array spindle is denoted as: Then it is located in space The normalized amplitude-phase return path difference of the target position in the main axis channel is denoted as: ； Use the array principal axis to estimate the azimuth angle of the target: Assuming the pitch angle is 0°, the phase compensation formula is used. A steering vector table is generated, and digital beamforming is performed on the echo signal of the main spindle array to obtain: Find the modulus The maximum value corresponding to Value, denoted as ; Will[ Using the angle values ​​within the specified range as prior values, the phase compensation formula is applied. A steering vector table is generated, and digital beamforming is performed on the echo signals of all two-dimensional array channels to obtain: ; Find the modulus The maximum value corresponding to The value is the two-dimensional angle of the target in space.

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