Design method for thickness of wave-transparent material of bumper of intelligent vehicle

Abstract

The invention relates to a bumper wave-transparent material thickness design method for an intelligent vehicle, and the method comprises the following steps: sequentially obtaining the absorption loss, the reflection loss and the interference fluctuation loss based on the propagation loss in the process that radar electromagnetic waves enter a bumper material thickness layer and a paint layer from the air and then are transmitted to the air, and obtaining the final total loss; when an electromagnetic wave frequency spectrum is fixed, plastic absorption electromagnetic wave loss and plastic thickness are in a linear relation, and when interference loss is integral multiples of half wavelength, total loss is minimum, so that the plastic thickness is obtained. The method has the beneficial effects that the accuracy of loss calculation is greatly improved by calculating the absorption loss, the reflection loss, the interference fluctuation loss and the final total loss, and the accuracy of loss calculation is greatly improved based on the rules that the plastic absorption loss and the thickness are in a linear relation when the electromagnetic wave spectrum is fixed and the thickness is an integral multiple of the half-wavelength when the interference loss is minimum. The thickness of the plastic that minimizes the total loss may be determined.

Description

Technical Field

[0001] This invention belongs to the technical field of automotive bumper material thickness, specifically relating to a design method for the translucent material thickness of a smart car bumper. Background Technology

[0002] With the continuous improvement of new energy vehicles and the level of intelligence, high-performance and highly stable hardware systems, especially millimeter-wave radar, are crucial for intelligent vehicles' "eyes" and "ears." As a key sensor in the environmental perception system of intelligent vehicles, the perception accuracy of millimeter-wave radar directly determines the effectiveness of intelligent driving functions.

[0003] Millimeter-wave radar is typically mounted inside the vehicle bumper, which inevitably makes it directly affected by the bumper's structural design. Specifically, the bumper's material selection, thickness distribution, and molding process all interfere with the electromagnetic wave propagation path of the millimeter-wave radar, thus affecting the accuracy of radar signal reception and resolution. Traditional technologies, such as the millimeter-wave radome and millimeter-wave radar provided by CN21029581U, have insufficient precision in the design of the radome, which increases the risk of interference in the electromagnetic wave propagation path and affects the accuracy of radar signal reception and resolution. Summary of the Invention

[0004] This invention provides a method for designing the thickness of the wave-transparent material in the bumper of a smart car, aiming to solve the problems of insufficient precision in existing designs, which increases the risk of interference in the electromagnetic wave propagation path and affects the accuracy of radar signal reception and analysis.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a method for designing the thickness of the wave-transparent material in the bumper of a smart car, comprising the following steps: Based on the propagation loss of radar electromagnetic waves as they travel from the air into the thick layer of the bumper material and paint, and then back into the air, the absorption loss is obtained sequentially. Reflection loss and interference fluctuation loss Thus, the final total loss can be obtained. ; Given a fixed electromagnetic spectrum, the electromagnetic wave absorption loss of plastic is related to the plastic thickness. The relationship is linear; during interference loss, when... When the wavelength is an integer multiple of half the wavelength, the total loss is minimized, thus allowing the determination of the plastic thickness. .

[0006] Furthermore, the acquisition of absorption loss Specifically, it includes the following steps: Based on total projection loss Intensity transmittance and the attenuation constant in the medium Thus, the absorption loss is obtained. .

[0007] Furthermore, the attenuation constant in the medium The acquisition of [the resource] specifically includes the following steps: Based on vacuum wavenumber and wavenumber in the medium Obtain the attenuation constant in the medium and the phase constant of propagation in the medium .

[0008] Furthermore, the acquisition of intensity transmittance Specifically, it includes the following steps: Based on the first transmitted wave The second transmitted wave The third transmitted wave Obtain the total transmitted electric field .

[0009] Furthermore, the propagation factor within the medium The first transmitted wave The second transmitted wave and the third transmitted wave The acquisition of [the resource] specifically includes the following steps: Obtain the propagation factor within the medium And based on the propagation factor within the medium Obtain the first transmitted wave Obtain the first transmitted wave An additional second transmitted wave And, to obtain the second transmitted wave More than a third transmitted wave that goes back and forth .

[0010] Furthermore, the acquisition of the propagation factor within the medium Specifically, it includes the following steps: Based on the attenuation constant in the medium and the phase constant of propagation in the medium Obtain the propagation factor within the medium. .

[0011] Furthermore, it also includes the following steps: Acquiring the Fresnel front surface reflection of electromagnetic waves from air into a medium and front surface transmission And, to obtain the Fresnel back surface transmission of electromagnetic waves from the medium into the air. and back surface transmission The round-trip transmission product is obtained. ; Obtain the front surface reflection coefficient Reflectance coefficient of the back surface We obtain the round-trip reflection product. .

[0012] Furthermore, the acquisition of reflection loss The condition is Fresnel loss from two projections, with no multiple reflections.

[0013] Furthermore, it also includes: Also includes: Obtain the thickness of the bumper plastic material and paint layer thickness And according to the thickness of the bumper plastic material and paint layer thickness The plastic thickness was verified by the design. .

[0014] The advantages of this invention compared to the prior art are: 1. Through complete calculation of the absorption loss of radar electromagnetic waves during their entire propagation process from air into the thick layer of bumper material, through the paint layer, and back into the air. Reflection loss and interference fluctuation loss And calculate the final total loss accordingly. Compared to the traditional design approach that only focuses on a single factor, this method can more comprehensively reflect the energy loss during electromagnetic wave propagation, significantly improving the accuracy of loss calculation and laying a solid theoretical foundation for the optimized design of material thickness parameters. 2. Based on the principles that "the absorption loss of plastic is linearly related to its thickness when the electromagnetic wave spectrum is constant" and "the thickness is an integer multiple of half the wavelength when the interference loss is minimum," the plastic thickness that minimizes the total loss can be determined. This design ensures that the bumper material thickness is in an optimal state of wave transmission, minimizing attenuation and interference with millimeter-wave radar electromagnetic signals and effectively guaranteeing the transmission quality of radar signals. Attached Figure Description

[0015] Figure 1 A radar installation schematic diagram illustrating a method for designing the thickness of a wave-transparent material in a bumper for an intelligent vehicle, as provided in an embodiment of the present invention. Figure 2 A schematic diagram of the actual electromagnetic wave thickness in a method for designing the translucent material thickness of a smart car bumper, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram illustrating the design material thickness of a wave-transparent material design method for a smart car bumper, provided as an embodiment of the present invention.

[0016] Explanation of reference numerals in the attached figures: 1. Radar; 2. Material thickness of the bumper in the radar radiation zone; 3. Material thickness of the bumper in the non-radar radiation zone. Detailed Implementation

[0017] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0018] See Figure 2 and Figure 3 As shown, this invention discloses a method for designing the thickness of the wave-transparent material in the bumper of a smart car, including the following steps: Obtain the thickness of the bumper plastic material Thickness of the plastic material in the bumper It is 2-3.5mm; Obtain the paint thickness on the plastic bumper The thickness is 20-50µm, depending on the thickness of the plastic material. Much greater than the thickness of the paint Therefore, the paint thickness can be ignored. To obtain the actual thickness of the bumper plastic material. The thickness of the plastic material in the bumper that allows electromagnetic waves to pass through. They are roughly the same, therefore, .

[0019] Obtain the round-trip transmission product The process includes the following steps: Electromagnetic waves are reflected from the Fresnel front surface of the medium as they enter from air. The formula is: (1); Front surface transmission The formula is: (2); Rear surface transmission The formula is: (3); Rear surface transmission The formula is: (4); Round trip transmission product The formula is: (5); According to the formula: (6); get (7); Front surface reflection coefficient The formula is: (8); Rear surface reflection coefficient The formula is: (9); Obtain the reflection coefficients of the front and back surfaces The formula is: (10); Obtain the attenuation constant in the medium and the phase constant of propagation in the medium This includes the following steps: vacuum wavenumber The formula is: (11); The attenuation constant in the medium is given by the following formula: (12); Thus, the attenuation constant in the medium is obtained. The formula is: (13); Obtain the propagation phase constant in the medium The formula is: (14); Obtain the propagation factor within the medium The formula is: (15); In the formula: For phase change; For attenuation; Obtain the first transmitted wave The formula is: (16); Obtain the second transmitted wave (One more round trip than the first one) The formula is: (17); Obtain the third transmitted wave (one more round trip than the second one). The formula is: (18); The total transmitted electric field is then obtained, and the formula is: (19); because ,get ;because It is a plural number, so It is also a plural number. It is also a plural number; because The common ratio of the series is obtained as .

[0020] Combining front and rear surface reflectance (10) We get: (20); Therefore, ; Obtain intensity transmittance , (twenty one); in, ; Total transmission loss The formula is: (twenty two); in, Combine formulas (11) and (13). ; Absorption loss (twenty three); Combination Therefore, ; Reflection loss The condition is Fresnel loss from two projections; without multiple reflections, the reflection loss is... The formula is: (twenty four); Combining reality Oscillations equivalent to the average value, interference fluctuation loss The formula is: (25); The final formula for total loss is derived. The formula is: ; in: and It is irrelevant, only related to related; It is an interference term, following oscillation; The first term is the constant reflection loss (and...) (Irrelevant), the second term is an interference term (with) Related to oscillation), the third term is absorption loss (related to oscillation). (Proportional)

[0021] Therefore, theoretically, when the electromagnetic wave spectrum is constant, the electromagnetic wave absorption loss of plastic is related to its thickness. The relationship is linear; when interference loss is considered, when When it is an integer multiple of half the wavelength, Minimum, at this time ; Where: is the complex dielectric constant of the plastic, which has different values ​​for different materials and can be obtained through actual measurement. The measured value is 2.432 for PP+EPDM-TD15 and 2.500 for PP+EPDM-TD20; N is an integer.

[0022] The specific implementation method is as follows: (1) For PP+EPDM-TD15 material: ; ; ; Where N takes the values ​​1, 2, 3, 4, ...

[0023] (2) For PP+EPDM-TD20 material: ; ; ; Where N takes the values ​​1, 2, 3, 4, ...

[0024] See Figure 1 As shown, here is implementation case one: (1) When selecting 24GHz radar 1, if the bumper material is PP+EPDEM-TD15, the bumper material thickness 2 in the radar transmission area is designed to be 4.0045mm. Considering the actual manufacturing precision, the local material thickness 2 of the bumper in the transmission area is designed to be 4.005mm. The bumper material thickness 3 in the non-transmission area of ​​the radar is designed to be 2.5mm, 2.8mm or 3.0mm. If the bumper material is PP+EPDEM-TD20, the bumper material thickness 2 in the radar transmission area is designed to be 3.9496mm. Considering the actual manufacturing precision, the local material thickness of the bumper in the transmission area is designed to be 3.95mm. The bumper material thickness 3 in the non-transmission area of ​​the radar is designed to be 2.5mm, 2.8mm or 3.0mm.

[0025] (2) When selecting 60GHz radar 1, if the bumper material is PP+EPDEM-TD15, the bumper material thickness 2 in the radar transmission area is designed to be 1.599mm. Considering the actual manufacturing precision, the local material thickness 2 of the bumper in the transmission area is designed to be 1.6mm, and the bumper material thickness 3 in the non-transmission area of ​​the radar is designed to be 2.5mm, 2.8mm or 3.0mm. If the bumper material is PP+EPDEM-TD20, the bumper material thickness 2 in the radar transmission area is designed to be 1.5771mm. Considering the actual manufacturing precision, the local material thickness 2 of the bumper in the transmission area is designed to be 1.577mm, and the bumper material thickness 3 in the non-transmission area of ​​the radar is designed to be 2.5mm, 2.8mm or 3.0mm.

[0026] (3) When selecting 77GHz radar 1, if the bumper material is PP+EPDEM-TD15, due to the large material thickness of the bumper and the material thickness being less than 1.5mm, injection molding is prone to areas with insufficient filling, so N is taken as 2. Then, the bumper material thickness 2 in the radar transmission area is designed to be 1.247*2=2.494mm, and the bumper material thickness 3 in the radar non-transmission area is designed to be 2.5mm, 2.8mm or 3.0mm; if the bumper material is PP+EPDEM-TD20, the bumper material thickness 2 in the radar transmission area is designed to be 1.2299*2=2.4598mm. Considering the actual manufacturing precision, the local material thickness 2 of the bumper in the transmission area is designed to be 2.46mm, and the bumper material thickness 3 in the radar non-transmission area is designed to be 2.5mm, 2.8mm or 3.0mm.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for designing the thickness of the wave-transparent material in the bumper of a smart car, characterized in that, Includes the following steps: Based on the propagation loss of radar electromagnetic waves as they travel from the air into the thick layer of the bumper material and paint, and then back into the air, the absorption loss is obtained sequentially. Reflection loss and interference fluctuation loss Thus, the final total loss can be obtained. ; Given a fixed electromagnetic spectrum, the electromagnetic wave absorption loss of plastic is related to the plastic thickness. The relationship is linear; during interference loss, when... When the wavelength is an integer multiple of half the wavelength, the total loss is minimized, thus allowing the determination of the plastic thickness. .

2. The method for designing the thickness of the wave-transparent material in the bumper of a smart car as described in claim 1, characterized in that, The acquisition of absorption loss Specifically, it includes the following steps: Based on total projection loss Intensity transmittance and the attenuation constant in the medium Thus, the absorption loss is obtained. .

3. The method for designing the thickness of the wave-transparent material in the bumper of a smart car as described in claim 2, characterized in that, Attenuation constant in the medium The acquisition of [the resource] specifically includes the following steps: Based on vacuum wavenumber and wavenumber in the medium Obtain the attenuation constant in the medium and the phase constant of propagation in the medium .

4. The method for designing the thickness of the wave-transparent material in the bumper of an intelligent vehicle as described in claim 3, characterized in that, The acquisition of intensity transmittance Specifically, it includes the following steps: Based on the first transmitted wave The second transmitted wave The third transmitted wave Obtain the total transmitted electric field .

5. The method for designing the thickness of the wave-transparent material in the bumper of an intelligent vehicle as described in claim 4, characterized in that, The propagation factor within the medium The first transmitted wave The second transmitted wave and the third transmitted wave The acquisition of [the resource] specifically includes the following steps: Obtain the propagation factor within the medium And based on the propagation factor within the medium Obtain the first transmitted wave Obtain the first transmitted wave An additional second transmitted wave And, to obtain the second transmitted wave More than a third transmitted wave that goes back and forth .

6. The method for designing the thickness of the wave-transparent material in the bumper of an intelligent vehicle as described in claim 5, characterized in that, The acquisition of propagation factors within the medium Specifically, it includes the following steps: Based on the attenuation constant in the medium and the phase constant of propagation in the medium Obtain the propagation factor within the medium. .

7. The method for designing the thickness of the wave-transparent material in the bumper of an intelligent vehicle as described in claim 5, characterized in that, It also includes the following steps: Acquiring the Fresnel front surface reflection of electromagnetic waves from air into a medium and front surface transmission And, to obtain the Fresnel back surface transmission of electromagnetic waves from the medium into the air. and back surface transmission The round-trip transmission product is obtained. ; Obtain the front surface reflection coefficient Reflectance coefficient of the back surface We obtain the round-trip reflection product. .

8. The method for designing the thickness of the wave-transparent material in the bumper of a smart car as described in claim 1, characterized in that, The acquisition of reflection loss The condition is Fresnel loss from two projections, with no multiple reflections.

9. The method for designing the thickness of the wave-transparent material in the bumper of an intelligent vehicle as described in claim 1, characterized in that, Also includes: Obtain the thickness of the bumper plastic material and paint layer thickness And according to the thickness of the bumper plastic material and paint layer thickness The plastic thickness was verified by the design. .

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