A radar installation angle error estimation method

Abstract

The present application relates to a method for estimating the radar installation angle error. The method comprises: placing a radar array and an installation rail in a radar installation scenario; obtaining the coordinates of the channel on the radar array from the center of the array and the installation error angle of the radar array in azimuth and pitch; calculating the channel reception data of the target on the rail according to the coordinates and the installation error angle; using Taylor series expansion of the channel reception data when the installation error angle is zero and discarding the second-order and higher-order terms to obtain optimized channel reception data; dividing both sides of the optimized channel reception data by a constant term that is independent of the installation error angle to obtain updated channel reception data; representing the updated channel reception data as a linear model, performing deformation and solution according to the linear model, and obtaining the radar installation angle error estimation result. This method can quickly estimate the installation angle deviation and is simple and practical.

Description

Technical Field

[0001] The present application relates to the technical field of radar error estimation, and in particular to a radar installation angle error estimation method. Background Art

[0002] At present, in the process of active calibration of radar array or measurement of amplitude and phase characteristics of radiation pattern, it is often necessary to accurately align the radar normal with the center of the two-dimensional rail, and then analyze the radiation pattern amplitude characteristics of the radar array by receiving the echo of the target with precise moving position on the rail. Due to the non-horizontal array placement platform or the uneven shape of the array system, the error of the radar coordinate system and the rail coordinate system, etc., the actual radar normal will not be accurately aligned with the center of the two-dimensional rail, resulting in measurement error of the radiation pattern and channel calibration error. In some multi-sensor fusion processing such as data fusion of millimeter-wave radar and camera, the calibration of the installation angle is also an important prerequisite for the normal use of the radar and successful data fusion. Therefore, it is necessary to estimate the radar installation angle error and adjust the direction of the radar array normal according to the error estimation result.

[0003] For the radar installation angle error of the advanced driver assistance system (ADAS), the researchers proposed a grid mapping calibration method, which arranges two obvious point targets (such as angle counterpoints) on the site, and then drives a vehicle with a non-installation angle calibration past the two targets, where the position of the vehicle is precisely known. When there is no installation error, the same target point measured by the radar will always be mapped to the same position grid, otherwise the same target will correspond to multiple position grids. Subsequently, the position grids of multiple groups of targets are independently calculated by assuming different installation angle errors, and the result with the least occupied grid is the estimated value of the radar installation angle error. This method is highly feasible for small radars, but it is difficult to experiment with larger radar systems, and the calibration process takes too long to quickly derive the installation angle deviation. Summary of the invention

[0004] Based on this, it is necessary to provide a radar installation angle error estimation method that can quickly estimate the installation angle deviation and is simple and practical to address the above technical problems.

[0005] A radar installation angle error estimation method, the method comprising:

[0006] Place the radar array and installation rail in the radar installation scenario; obtain the coordinates of the channel on the radar array from the center of the array and the installation error angle of the radar array in azimuth and elevation; calculate the channel reception data of the target on the rail based on the coordinates and installation error angle, including:

[0007] The channel receiving data of the target on the guide rail is calculated based on the coordinates and the installation error angle:

[0008] ;

[0009] ;

[0010] in, represents the total number of channels of the radar array, represents the azimuth of the target, represents the pitch angle of the target, represents the signal wavelength, Indicates The horizontal axis of the channel, represents the azimuth angle in the installation error angle, represents the pitch angle in the installation error angle, Indicates The vertical coordinate of the channel, Indicates the channel number of the radar array;

[0011] The channel receiving data is expanded using Taylor series when the installation error angle is zero and the second-order and higher-order terms are discarded to obtain the optimized channel receiving data; both sides of the optimized channel receiving data are divided by a constant term that is unrelated to the installation error angle to obtain the updated channel receiving data;

[0012] The updated channel receiving data is represented as a linear model, and the deformation solution is performed according to the linear model to obtain the radar installation angle error estimation result.

[0013] In one embodiment, the channel receiving data is expanded using Taylor series when the installation error angle is zero and the second-order and higher-order terms are discarded to obtain the optimized channel receiving data, including:

[0014] When the installation error angle is zero, the channel receiving data is expanded using Taylor series and the second-order and higher-order terms are discarded. The optimized channel receiving data is obtained as follows:

[0015] ;

[0016] in, represents the azimuth of the target, represents the pitch angle of the target, represents the signal wavelength, Indicates The horizontal axis of the channel, Indicates The vertical coordinate of the channel, represents the azimuth angle in the installation error angle, Indicates the pitch angle within the installation error angle.

[0017] In one embodiment, both sides of the optimized channel reception data are divided by a constant term that is independent of the installation error angle to obtain updated channel reception data, including:

[0018] Divide both sides of the optimized channel receiving data by a constant term that is independent of the installation error angle, and the updated channel receiving data is obtained as follows:

[0019] ;

[0020] in, represents the azimuth of the target, represents the pitch angle of the target, represents the signal wavelength, Indicates The horizontal axis of the channel, Indicates The vertical coordinate of the channel, represents the azimuth angle in the installation error angle, Indicates the pitch angle within the installation error angle.

[0021] In one of the embodiments, representing the updated channel reception data as a linear model includes:

[0022] make

[0023] , , ,in means Take the phase angle, because and Very small, There will be no phase ambiguity in the phase angle, and the updated channel receiving data can be expressed as a linear model:

[0024] ;

[0025] in,

[0026] , represents the total number of channels of the radar array, Indicates the channel number of the radar array, the superscript T Represents a transpose operation.

[0027] In one embodiment, a deformation solution is performed according to a linear model to obtain a radar installation angle error estimation result, including:

[0028] According to the linear model, the deformation solution is obtained, and the estimated result of the radar installation angle error is:

[0029] .

[0030] The above-mentioned radar installation angle error estimation method first places the radar array and the installation rail in the radar installation scene. The installation of the rail is to accurately control the position of the radiation source so that it is suitable for the subsequent processing flow. Then, the coordinates of the channel on the radar array from the center of the array and the installation error angle of the radar array in azimuth and pitch are obtained; the channel receiving data of the target on the rail is calculated according to the coordinates and the installation error angle, and the channel receiving data is expanded using Taylor series when the installation error angle is zero and the second-order and higher-order terms are discarded to obtain the optimized channel receiving data; both sides of the optimized channel receiving data are divided by a constant term that is independent of the installation error angle to obtain the updated channel receiving data, and the updated channel receiving data is represented as a linear model, and the linear model is deformed and solved to obtain the radar installation angle error estimation result. Compared with the existing grid mapping calibration method, the movement of the platform where the radar is located is avoided. It only needs to place a rail in front of the radar and accurately move the radiation source to realize the calibration process, which is more conducive to the realization of the experiment. Moreover, the present application can accurately estimate the angular installation error of the radar, and according to the estimation result, the direction of the radar normal can be accurately readjusted, which has very important practical value for radar array performance testing and multi-sensor joint processing scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a flow chart of a radar installation angle error estimation method in one embodiment;

[0032] Figure 2 A schematic diagram of a geometric model of array normal pointing error in one embodiment;

[0033] Figure 3 It is a schematic diagram of the estimation result of the azimuth installation error in one embodiment;

[0034] Figure 4 It is a schematic diagram of the estimation result of the pitch angle installation error in another embodiment. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] In one embodiment, Figure 1 As shown, a radar installation angle error estimation method is provided, comprising the following steps:

[0037] Step 1: Place the radar array and the installation rail in the radar installation scenario; obtain the coordinates of the channel on the radar array from the center of the array and the installation error angle of the radar array in azimuth and elevation; calculate the channel reception data of the target on the rail according to the coordinates and the installation error angle.

[0038] Build the experimental scene, including the installation of the radar array on the platform, installation of the guide rail bracket, and rough angle alignment. The installation of the guide rail is to accurately control the position of the radiation source so that it is suitable for subsequent processing. This application uses the phase difference of the received echo on different channels of the array to realize the installation angle deviation estimation. Under far-field conditions, such as Figure 2 As shown in the figure, it is a schematic diagram of the geometric model of the array normal pointing error. Assuming that the number of channels of the array is , No. The coordinates of each channel from the center of the array are The installation error angles of the array normal relative to the Z direction in azimuth and elevation are , then the coordinates on the guide rail are The goal of a The channel receiving data can be expressed as

[0039] (1)

[0040] Step 2, when the installation error angle is zero, the channel reception data is expanded using a Taylor series and the second-order and higher-order terms are discarded to obtain the optimized channel reception data; both sides of the optimized channel reception data are divided by a constant term that is independent of the installation error angle to obtain the updated channel reception data.

[0041] Since the pointing error is generally small, we can replace equation (1) with Use Taylor series expansion near and discard the second-order and higher-order terms to get

[0042] (2)

[0043] Divide both sides of equation (2) by Irrelevant constant terms, we get

[0044] (3)

[0045] Step 3: Represent the updated channel receiving data as a linear model, perform deformation solution according to the linear model, and obtain the radar installation angle error estimation result.

[0046] make

[0047] , , ,in means Take the phase angle. and Very small, The phase angle will not have phase ambiguity. Then equation (3) can be expressed as the linear model of equation (4)

[0048] (4)

[0049] in, .

[0050] Then the least squares estimate of the radar installation angle error can be expressed as:

[0051] (5)

[0052] In the above radar installation angle error estimation method, the radar array and the installation rail are first placed in the radar installation scene. The installation of the rail is to accurately control the position of the radiation source so that it is suitable for the subsequent processing flow. Then, the coordinates of the channel on the radar array from the center of the array and the installation error angle of the radar array in azimuth and pitch are obtained; the channel receiving data of the target on the rail is calculated according to the coordinates and the installation error angle, and the channel receiving data is expanded using Taylor series when the installation error angle is zero and the second-order and higher-order terms are discarded to obtain the optimized channel receiving data; both sides of the optimized channel receiving data are divided by a constant term that is independent of the installation error angle to obtain the updated channel receiving data, and the updated channel receiving data is represented as a linear model, and the linear model is deformed and solved to obtain the radar installation angle error estimation result. Compared with the existing grid mapping calibration method, the movement of the platform where the radar is located is avoided. It only needs to place a rail in front of the radar and accurately move the radiation source to realize the calibration process, which is more conducive to the realization of the experiment. Moreover, the present application can accurately estimate the angular installation error of the radar, and according to the estimation result, the direction of the radar normal can be accurately readjusted, which has very important practical value for radar array performance testing and multi-sensor joint processing scenarios.

[0053] In one embodiment, calculating channel receiving data of a target on a guide rail according to coordinates and installation error angles includes:

[0054] The channel receiving data of the target on the guide rail is calculated based on the coordinates and installation error angle:

[0055] ;

[0056] ;

[0057] in, represents the total number of channels of the radar array, represents the azimuth of the target, represents the pitch angle of the target, represents the signal wavelength, Indicates The horizontal axis of the channel, Indicates The vertical coordinate of the channel, represents the azimuth angle in the installation error angle, represents the pitch angle in the installation error angle, Indicates the channel number of the radar array.

[0058] In one embodiment, the channel receiving data is expanded using Taylor series when the installation error angle is zero and the second-order and higher-order terms are discarded to obtain the optimized channel receiving data, including:

[0059] When the installation error angle is zero, the channel receiving data is expanded using Taylor series and the second-order and higher-order terms are discarded. The optimized channel receiving data is obtained as follows:

[0060] ;

[0061] in, represents the azimuth of the target, represents the pitch angle of the target, represents the signal wavelength, Indicates The horizontal axis of the channel, Indicates The vertical coordinate of the channel, represents the azimuth angle in the installation error angle, Indicates the pitch angle within the installation error angle.

[0062] In one embodiment, both sides of the optimized channel reception data are divided by a constant term that is independent of the installation error angle to obtain updated channel reception data, including:

[0063] Divide both sides of the optimized channel receiving data by a constant term that is independent of the installation error angle, and the updated channel receiving data is obtained as follows:

[0064] ;

[0065] in, represents the azimuth of the target, represents the pitch angle of the target, represents the signal wavelength, Indicates The horizontal axis of the channel, Indicates The vertical coordinate of the channel, represents the azimuth angle in the installation error angle, Indicates the pitch angle within the installation error angle.

[0066] In one of the embodiments, representing the updated channel reception data as a linear model includes:

[0067] make

[0068] , , ,in means Take the phase angle, because and Very small, There will be no phase ambiguity in the phase angle, and the updated channel receiving data can be expressed as a linear model:

[0069] ;

[0070] in, , represents the total number of channels of the radar array, Indicates the channel number of the radar array, the superscript T Represents a transpose operation.

[0071] In one embodiment, a deformation solution is performed according to a linear model to obtain a radar installation angle error estimation result, including:

[0072] According to the linear model, the deformation solution is obtained, and the estimated result of the radar installation angle error is:

[0073] .

[0074] In a specific embodiment, the radar array is first placed on a platform, and a precisely movable guide rail bracket is installed in front of the platform so that the normal direction of the radar array is roughly perpendicular to the guide rail plane. Then the horizontal distance Z0 between the center of the radar array and the center of the guide rail is measured by a laser pen. Next, a calibration source is set near the center of the guide rail coordinates, requiring the source to radiate or reflect the electromagnetic wave as much as possible to avoid the receiver random noise causing deviations in the measurement results. Then the signal transceiver is started, the echo data is received, and the observation matrix is ​​calculated based on the precise position of the source, which is expressed as a linear model of formula (4). Finally, the installation angle error of the radar can be estimated by the least squares method of formula (5).

[0075] In the specific experimental process, the simulation experiment sets the array to be installed with installation errors in azimuth and elevation respectively. .set up , the coordinates of the calibration source on the guide plane are , which is equivalent to The installation error angle obtained according to formula (5) is It can be seen that the proposed method can estimate the installation error angle of the array more accurately. To further investigate the performance of the algorithm, the azimuth installation error is set to -3°~3°, the elevation installation error is set to -3°~3°, and the angle installation error estimation is calculated, as shown in the following figure: Figure 3 and Figure 4 As shown, it can be seen that the estimation of the azimuth error and the elevation installation error does not affect each other, and in the range of the installation error of -3°~3°, the estimation of the installation error of the azimuth angle and the elevation angle is very accurate.

[0076] It should be understood that although Figure 1 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 1 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0077] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A radar installation angle error estimation method, characterized in that: The method comprises: Placing a radar array and a mounting rail in a radar installation scenario; obtaining coordinates of a channel on the radar array from a center of the array and an installation error angle of the radar array in azimuth and elevation; and calculating channel reception data of a target on the rail according to the coordinates and the installation error angle, including: The channel receiving data of the target on the guide rail is calculated based on the coordinates and the installation error angle: ； ； in, represents the total number of channels of the radar array, represents the azimuth of the target, represents the pitch angle of the target, represents the signal wavelength, Indicates The horizontal axis of the channel, represents the azimuth angle in the installation error angle, represents the pitch angle in the installation error angle, Indicates The vertical coordinate of the channel, Indicates the channel number of the radar array; The channel receiving data is expanded using Taylor series when the installation error angle is zero and the second-order and higher-order terms are discarded to obtain optimized channel receiving data; both sides of the optimized channel receiving data are divided by a constant term that is unrelated to the installation error angle to obtain updated channel receiving data; The updated channel receiving data is represented as a linear model, and a deformation solution is performed according to the linear model to obtain a radar installation angle error estimation result.

2. The method according to claim 1, characterized in that The channel receiving data is expanded using Taylor series when the installation error angle is zero and the second-order and higher-order terms are discarded to obtain the optimized channel receiving data, including: When the installation error angle is zero, the channel receiving data is expanded using Taylor series and the second-order and higher-order terms are discarded, and the optimized channel receiving data is obtained as follows: ； in, represents the azimuth of the target, represents the pitch angle of the target, represents the signal wavelength, Indicates The horizontal axis of the channel, represents the azimuth angle in the installation error angle, represents the pitch angle in the installation error angle, Indicates The vertical coordinate of the channel.

3. The method according to claim 1, characterized in that Dividing both sides of the optimized channel reception data by a constant term that is independent of the installation error angle, to obtain updated channel reception data, including: Divide both sides of the optimized channel reception data by a constant term that is independent of the installation error angle to obtain the updated channel reception data: ； in, represents the azimuth of the target, represents the pitch angle of the target, represents the signal wavelength, Indicates The horizontal axis of the channel, represents the azimuth angle in the installation error angle, represents the pitch angle in the installation error angle, Indicates The vertical coordinate of the channel.

4. The method according to claim 3, characterized in that Representing the updated channel reception data as a linear model, comprising: make , , ,in means Take the phase angle, because and Very small, There will be no phase ambiguity in the phase angle, and the updated channel receiving data is represented as a linear model: ； in, , represents the total number of channels of the radar array, Indicates the channel number of the radar array, the superscript T Represents a transpose operation.

5. The method according to claim 4, characterized in that The linear model is deformed and solved to obtain the radar installation angle error estimation result, including: According to the linear model, the deformation solution is performed and the radar installation angle error estimation result is obtained as follows: .

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