Communication antenna pose optimization method for vehicle communication system immunity test

Abstract

The invention discloses a communication antenna pose optimization method for a vehicle communication system immunity test, and the method comprises the steps: building an electromagnetic wave propagation model from an interference antenna to a communication antenna, and the propagation model comprises the path loss calculation of a direct path and a ground reflection path; establishing an electromagnetic wave propagation model from the communication antenna to the tested antenna, wherein the propagation model comprises path loss calculation of a direct incidence path and a ground reflection path; based on the propagation model, constructing an optimization equation with constraints; and traversing and updating the position and attitude of the communication antenna, solving the minimum value of the objective function, and determining the optimal pose of the communication antenna.

Description

Technical Field

[0001] The present invention relates to the field of vehicle communication, and particularly to an optimal method for the pose of a communication antenna in the immunity test of a vehicle communication system. Background Art

[0002] With the development of automobiles towards electrification and intelligence, in order to meet the increasing functional requirements, including navigation and positioning, assisted driving, in-vehicle entertainment, etc., the wireless communication systems installed in vehicles are becoming increasingly rich. There is a receiving path in the vehicle communication system, which belongs to a sensitive device. There has been research on the electromagnetic immunity test of a single in-vehicle T-BOX (telematics box) in the ISO 11452-2 standard. However, the research on the immunity of vehicle communication systems in the whole vehicle environment is still in its infancy.

[0003] There are the following difficulties in building an immunity test system for a vehicle communication system in the whole vehicle environment:

[0004] 1. Substantial attenuation of the channel under the test layout of the connected vehicle working condition. According to the free space propagation loss model, as the spatial distance increases, the spatial loss of the signal also increases. In addition, the cable loss is also positively correlated with the cable length. The immunity test of the vehicle communication system in the whole vehicle environment is generally carried out in a semi-anechoic chamber for the whole vehicle. Due to the large size of such anechoic chambers, there is substantial attenuation in the propagation process of communication signals, generally up to 40 - 60 dB. The problem caused by the attenuation of communication signals is that the signal strength received at the receiving end is too small. When the received signal strength is close to / lower than the minimum receiving sensitivity of the receiving device, it will lead to unstable communication (the bit error rate is not 0) / communication interruption;

[0005] 2. Protection of connected devices under high-power working conditions. During the radiation immunity test, the intelligent connected test device will also receive signals with a relatively large signal strength. Generally, the maximum input power of the port of the intelligent connected device is much smaller than the immunity signal strength. Therefore, it is necessary to protect the connected device, otherwise the connected device will be damaged.

[0006] On the one hand, due to channel attenuation, signal amplification devices need to be added in the uplink and downlink paths to boost the communication signal. On the other hand, due to the high-power working condition of radiation immunity, the high-power signals received by the communication antenna will significantly affect the experimental accuracy and even cause damage to the experimental equipment.

[0007] The existing site layout scheme is generally the repeated experiment method. The specific operation is to change the position of the communication antenna, place the communication antenna at several positions, and measure the signal strength at the receiving end when the immunity signal is normally transmitted. Summary of the Invention

[0008] To achieve the above and other related objectives, the present invention discloses an optimal method for the pose of a communication antenna in the immunity test of a vehicle communication system, including:

[0009] Establish an electromagnetic wave propagation model from the interference antenna to the communication antenna, and the propagation model includes the calculation of path loss for the direct path and the ground reflection path;

[0010] Establish an electromagnetic wave propagation model from the communication antenna to the antenna under test, and the propagation model includes the calculation of path loss for the direct path and the ground reflection path;

[0011] Based on the above propagation model, construct an optimization equation with constraints, and the objective function of the optimization equation is:

[0012] ;

[0013] ;

[0014] Wherein, is the signal strength received by the antenna under test from the communication antenna in the communication path, is the signal strength received by the communication antenna from the immunity antenna in the interference path, is the signal strength threshold of the spectrum analyzer port, is the ambient noise floor;

[0015] By traversing and updating the position and pose of the communication antenna, solve the minimum value of the objective function to determine the optimal pose of the communication antenna.

[0016] Furthermore, the calculation of the direct path loss includes:

[0017] ;

[0018] Wherein, f is the signal frequency, is the direct path distance;

[0019] );

[0020] Wherein, is the distance from the transmitting antenna to the reflection point, is the distance from the reflection point to the receiving antenna.

[0021] Furthermore, the position update logic of the communication antenna includes:

[0022] ;

[0023] ;

[0024] ;

[0025] The position of the communication antenna after the i-th iteration is , and the position coordinates of the turntable center are ;

[0026] The constraint conditions for position update include:

[0027] ;

[0028] ;

[0029] are the length, width, and height of the vehicle body structure. The vehicle body structure is a cuboid, and L is the turntable radius.

[0030] Furthermore, the attitude update of the communication antenna includes:

[0031] Taking the initial attitude coordinate system as the reference, traverse the azimuth angle and elevation angle step by step at 30°, covering the entire spherical range;

[0032] Calculate the antenna pattern gain through the attitude transformation matrix, and the attitude transformation matrix includes rotation matrices around the X-axis, Y-axis, and Z-axis.

[0033] Furthermore, the attitude transformation matrix includes:

[0034] ;

[0035] ;

[0036] .

[0037] Furthermore, and are obtained in the following ways:

[0038]

[0039] Among them, the signal intensity emitted by the comprehensive tester is , the path loss from the comprehensive tester to the feeding end of the communication antenna is , the direct path loss of the antenna gain on the communication path is , and the reflection path loss of the antenna gain on the communication path ;

[0040]

[0041] Among them, the signal intensity emitted by the signal source is , the path loss from the signal source to the anti-interference antenna is , and the direct path loss of the antenna gain on the interference path is , the reflection path loss of the antenna gain on the interference path is .

[0042] Furthermore, the method is applicable to the semi-anechoic chamber environment and supports the immunity testing of cellular, WLAN, BT, and GNSS antennas.

[0043] On the other hand, the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the above method is implemented.

[0044] By adopting the above technical solutions, through mathematical modeling and global optimization algorithms, the optimal pose of the communication antenna is quickly determined, avoiding the cumbersome experiments of repeatedly adjusting the antenna position, greatly shortening the test cycle and reducing the labor and equipment costs. The optimization equation balances the signal strength of the communication path and the signal strength of the interference path with the objective function, ensuring communication stability while preventing high-power signals from damaging the equipment. The model supports the semi-anechoic chamber environment and is compatible with various antenna types such as cellular, WLAN, BT, and GNSS. Through parametric constraints (such as turntable range, vehicle body structure limitations) and attitude transformation matrices (covering omnidirectional angle steps), it can be flexibly adapted to different test scenarios and antenna configurations. Based on the electromagnetic field theory and antenna pattern characteristics, combined with the quantitative analysis of the propagation path, the subjectivity and randomness of the traditional method are eliminated, enhancing the consistency and theoretical support of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] With reference to the accompanying drawings and the following detailed description, the above and other features, advantages, and aspects of the various embodiments of the present disclosure will become more apparent. The drawings are used to better understand the solution and do not limit the present disclosure. In the drawings, the same or similar reference numerals represent the same or similar elements, where:

[0046] Figure 1 is a flowchart of the present invention;

[0047] Figure 2 is a schematic diagram of the direct path and the reflection path. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0049] Referring to Figure 1 , the embodiments of the present invention provide an optimal method for the pose of a communication antenna in the immunity testing of a vehicle communication system, including the following steps:

[0050] Establish an electromagnetic wave propagation model from the interfering antenna to the communication antenna, where the propagation model includes the path loss calculation of the direct path and the ground reflection path.

[0051] Establish an electromagnetic wave propagation model from the communication antenna to the antenna under test, where the propagation model includes the path loss calculation of the direct path and the ground reflection path.

[0052] Based on the above propagation model, construct an optimization equation with constraints.

[0053] By traversing and updating the position and attitude of the communication antenna, solve the minimum value of the objective function to determine the optimal position and attitude of the communication antenna.

[0054] The content involved in the method includes three parts: the electromagnetic wave propagation model from the interfering antenna to the communication antenna, the electromagnetic wave propagation model from the communication antenna to the antenna under test, and the position optimization equation with constraints.

[0055] First is the electromagnetic wave propagation model from the interfering antenna to the communication antenna. Let the projection of the phase center of the interfering antenna (which can be simplified to the geometric center of the antenna in actual calculation) on the ground be the origin to establish a space rectangular coordinate system. Then the known coordinate values of the phase center of the interfering antenna (which can be simplified to the geometric center of the antenna in actual calculation) relative to the origin , that is . In addition, the antenna attitude of the interfering antenna is also fixed. Therefore, its radiation pattern is also invariant in this coordinate system. The coordinate of the phase center of the communication antenna (which can be simplified to the geometric center of the antenna in actual calculation) relative to the origin is an unknown value and is also the object to be optimized. Let its coordinate be , that is . For the interfering antenna and the communication antenna, they can be regarded as a set of antennas above an infinite ideal conductor plane and surrounded by free space. Therefore, the electromagnetic wave propagation model between the two can be simplified to a combination of two propagation paths, one direct path and one reflection path.

[0056] Second is the electromagnetic wave propagation model from the communication antenna to the antenna under test. Considering the working characteristics of the antenna under test, the relative angular range of the position space where the communication antenna is arranged can be restricted. In addition, according to the free space propagation model, the greater the distance, the greater the loss. Therefore, when the communication antenna is too far away from the antenna under test, it is obviously not feasible. Therefore, the relative distance of the position space where the communication antenna is arranged is restricted. Here, antennas such as cellular, WLAN, and BT that work in the horizontal area and antennas such as GNSS that work in the roof area are analyzed respectively. The known coordinate value of the phase center of the antenna under test (which can be simplified to the geometric center of the antenna in actual calculation) relative to the origin , in addition, the antenna attitude of the antenna under test is also fixed, so its radiation pattern is also invariant in this coordinate system. The coordinates of the phase center of the communication antenna (which can be simplified to the geometric center of the antenna in actual calculations) relative to the origin are unknown values and are also the objects to be optimized. Let its coordinates be , that is . For the communication antenna and the antenna under test, they can be regarded as a set of antennas above an infinite ideal conductor plane and surrounded by free space. Therefore, the electromagnetic wave propagation model between the two can be simplified as a combination of two propagation paths, one direct path and one reflected path.

[0057] Finally, there is the optimization equation with constraints. The optimization equation expects that the signal received by the communication antenna from the anti-jamming antenna under the interference path is as low as possible and should be at least lower than the port signal strength threshold of the communication instrument; the signal received by the antenna under test from the communication antenna under the communication path is as high as possible and should be at least 10 dB higher than the background noise.

[0058] This method involves three important links: establishing the propagation model and simplification, updating the position and attitude transformation of the antenna, and establishing the objective function.

[0059] First, the propagation model and simplification. This link is applicable to both the propagation from the anti-jamming antenna to the communication antenna and the propagation from the communication antenna to the antenna under test. Since the ground of the anechoic chamber is a conductor and a smooth metal surface, and the other directions are all absorbing materials, the propagation path between the transmitting antenna and the receiving antenna can be approximately analyzed as only two paths, one direct path and one reflected path. As Figure 2 shown, A is the transmitting antenna and B is the receiving antenna. Then the propagation path is . Assuming that the ground is the XOY plane and the direction perpendicular to the ground upward is the Z axis, the coordinates of A are , and the coordinates of B are . Then there is

[0060]

[0061]

[0062]

[0063] From the free space loss formula it can be seen that when the frequency and the propagation distance are known, the free space loss can be solved. Here, the propagation distances of both propagation paths are known. The propagation distance of the direct path is , and the propagation distance of the reflected path is + In addition, this formula also reflects the positive correlation between free space loss and frequency.

[0064] Second, the position update and attitude transformation of the antenna. This will be described in two parts. One part introduces the logic of the communication antenna position update and the position constraint conditions, and the other part introduces the attitude transformation matrix and attitude update logic of the anti-interference antenna and the communication antenna.

[0065] First is the logic of the communication antenna position update and the position constraint conditions. Assume that the ground is the plane, and the direction perpendicular to the ground upward is the axis. Assume that the position coordinates of the turntable center are , the turntable radius is , the vehicle body is approximately a cuboid with length, width, and height of respectively, and the position of the communication antenna after the i-th iteration is . Then there is

[0066]

[0067]

[0068]

[0069] This update method is more in line with the sampling density distribution requirements for the communication antenna position search from the physical law compared to the linear step-by-step coordinate update method. The design goal is to receive as little anti-interference signal as possible and to have the transmitted communication signal be received by the antenna under test as much as possible. Therefore, a greater sampling density is required closer to the antenna under test, and the sampling density can be appropriately reduced farther away from the antenna under test.

[0070] The position update constraint conditions include two aspects. On the one hand, the communication antenna does not exceed the turntable range, and on the other hand, the communication antenna is not within the vehicle body structure. Therefore, the mathematical expression of the constraint is:

[0071]

[0072]

[0073] Next is the attitude transformation matrix and attitude update logic of the anti-interference antenna and the communication antenna. The relative position and attitude of the anti-interference antenna in the EMC test system with respect to the vehicle are generally fixed. Therefore, only one attitude transformation of the anti-interference antenna pattern coordinate system with respect to the calculation coordinate system is required. Assume that the attitude transformation angles of the anti-interference antenna pattern coordinate system with respect to the calculation coordinate system in the azimuth angle, roll angle, and pitch angle are respectively, and the propagation path vector in a certain direction of the anti-interference antenna in the test system is . The default coordinate system of the anti-interference antenna pattern, that is, a set of orthogonal basis vectors in the XOY plane of the coordinate system can be expressed as , . For these two sets of basis vectors, the new coordinate system orthogonal basis vectors are obtained by using the attitude transformation matrix respectively . Furthermore, the projection of the propagation path vector on the XOY plane of the transformed new coordinate system can be solved . From the projection and the basis vectors of the new coordinate system , the relative azimuth angle can be calculated from the included angle, and the relative pitch angle can be calculated from the propagation path vector and the basis vectors of the new coordinate system . According to the pitch angle and azimuth angle, the antenna gain data in this direction can be read. The attitude transformation matrices for rotation about the x-axis, y-axis, and z-axis are as follows

[0074]

[0075]

[0076]

[0077] The attitude of the communication antenna needs to be traversed according to certain rules, and the attitude transformation method is similar to that of the above anti-interference antenna. Attitude update rule: The initial attitude coordinate system coincides with the default coordinate system of the antenna pattern, and then the entire sphere is traversed step by step with a 30° pitch angle and a 30° azimuth angle. For any attitude during the traversal process, when the propagation path vector is determined, the antenna gain data in this propagation direction can be read by using the above attitude transformation method.

[0078] Third, establish the objective function. In this method, it is expected that: the lower the signal received by the communication antenna from the anti-interference antenna under the interference path, the better, and it should be at least lower than the port signal strength threshold of the communication instrument; the higher the signal received by the antenna under test from the communication antenna under the communication path, the better, and it should be at least 10 dB higher than the background noise. Assume that the signal intensity transmitted by the signal source is , the path loss from the signal source to the anti-interference antenna is , the signal intensity transmitted by the synthesizer is , the path loss from the synthesizer to the feed end of the communication antenna is , the ambient background noise is , the port signal intensity threshold of the synthesizer is , and the antenna under test is simplified to an ideal point source antenna. Traverse the position and attitude of the communication antenna. For any position and attitude combination , the direct path loss including the antenna gain and the reflection path loss on the interference path can be obtained., the direct path loss including the antenna gain on the communication path can also be obtained and the reflection path loss .

[0079] The lower the desired signal strength of the interference path, the better. Therefore, the lowest possible loss value in the path propagation should be taken. The lowest value occurs when the peak of the direct wave overlaps with the peak of the reflected wave. At this time, the signal strength received by the communication antenna under the interference path from the anti-interference antenna can be expressed as

[0080]

[0081] The higher the desired signal strength of the communication path, the better. Therefore, the highest possible loss value in the path propagation should be taken. The highest value occurs when the peak of the direct wave overlaps with the trough of the reflected wave. At this time, the signal strength received by the measured antenna under the communication path from the communication antenna can be expressed as

[0082]

[0083] Therefore, the objective function is set as:

[0084]

[0085]

[0086] Solving the minimum value of this objective function gives the optimal placement position and placement attitude of the communication antenna.

[0087] Those skilled in the art of this technology can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used here have the same meaning as the general understanding of those of ordinary skill in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless specifically defined.

[0088] For the method embodiments, for simplicity of description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the embodiments of the present invention are not limited by the described action sequence, because according to the embodiments of the present invention, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential to the embodiments of the present invention.

[0089] From the description of the above embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A communication antenna posture optimization method for vehicle communication system anti-interference test, characterized in that: include: Establishing an electromagnetic wave propagation model from the interference antenna to the communication antenna, wherein the propagation model includes path loss calculations for a direct path and a ground reflection path; Establishing an electromagnetic wave propagation model from the communication antenna to the antenna under test, wherein the propagation model includes path loss calculations for a direct path and a ground reflection path; Based on the above propagation model, a constrained optimization equation is constructed, and the objective function of the optimization equation is: ； ； in, is the signal strength sent by the communication antenna received by the antenna under test in the communication path, is the signal strength sent by the anti-interference antenna received by the communication antenna under the interference path, is the signal strength threshold of the comprehensive tester port, The background noise of the environment; By traversing and updating the position and posture of the communication antenna, the minimum value of the objective function is solved and the optimal position and posture of the communication antenna is determined.

2. The method according to claim 1, characterized in that The calculation of direct path loss includes: ； Where f is the signal frequency, is the direct path distance; )； in, is the distance from the transmitting antenna to the reflection point, is the distance from the reflection point to the receiving antenna.

3. The method according to claim 1, characterized in that The communication antenna position update logic includes: ； ； ； The position of the communication antenna after the i-th iteration is , the position coordinates of the center of the turntable are ; The constraints for location updates include: ； ； is the length, width and height of the vehicle body structure, the vehicle body structure is a rectangular parallelepiped, and L is the radius of the turntable.

4. The method according to claim 1, characterized in that: The communication antenna attitude update includes: Taking the initial attitude coordinate system as the reference, traverse the azimuth and elevation angles in 30° steps to cover the entire spherical range; The antenna pattern gain is calculated by an attitude transformation matrix, wherein the attitude transformation matrix includes rotation matrices around the X-axis, the Y-axis, and the Z-axis.

5. The method according to claim 4, characterized in that The posture transformation matrix includes: ； ； 。 6. The method according to claim 1, characterized in that and Ways to obtain include: ； Among them, the signal strength emitted by the comprehensive tester is , the path loss from the comprehensive tester to the communication antenna feed end is , the direct path loss of the antenna gain on the communication path is , the reflected path loss of the antenna gain on the communication path ; ； The signal strength emitted by the signal source is , the path loss from the signal source to the anti-interference antenna is , the direct path loss of the antenna gain on the interference path is , the reflected path loss of the antenna gain on the interference path is .

7. The method according to any one of claims 1 to 6, characterized in that: The method is applicable to semi-anechoic chamber environments and supports the immunity testing of cellular, WLAN, BT and GNSS antennas.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method described in any one of claims 1 to 7 is implemented.

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