Tolerance sensitivity analysis method suitable for vehicle-mounted head-up display

Abstract

The invention relates to a tolerance sensitivity analysis method suitable for a vehicle-mounted head-up display, and the method comprises the following steps: firstly, obtaining an image quality evaluation result after the design of a vehicle-mounted HUD is completed, adjusting the degree-of-freedom tolerance of an optical part and a whole machine of the vehicle-mounted HUD, obtaining a changed HUD image quality evaluation result, and carrying out the adjustment of the degree-of-freedom tolerance of the optical part and the whole machine; secondly, calculating image quality evaluation deviation before and after the variation of the tolerance amount of each degree of freedom of the vehicle-mounted HUD, then obtaining the sensitivity of the tolerance parameters of each degree of freedom of each optical element and the whole machine of the vehicle-mounted HUD and the imaging quality of the HUD system, obtaining the correlation degree of each degree of freedom tolerance parameter and the HUD image quality, finally obtaining the tolerance parameters which obviously influence the imaging quality of the HUD, distributing the HUD tolerance, and obtaining the image quality of the vehicle-mounted HUD. In a word, the method can comprehensively and completely analyze the correlation between each element of the HUD and the imaging effect of the HUD and between the whole machine and the imaging effect of the HUD, reasonably distributes the tolerance, reduces the design complexity of an HUD optical system, improves the optical path optimization efficiency, and improves the imaging effect of the HUD image.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle-mounted head-up display devices, and in particular relates to a tolerance sensitivity analysis method suitable for a vehicle-mounted head-up display. Background Art

[0002] The vehicle-mounted head-up display (HUD), also known as the head-up display, is an enhanced visual intelligent assisted driving device that improves road traffic safety driving. The vehicle-mounted HUD optical display system includes a picture generation unit (PGU), a secondary reflector, and a primary reflector. In order to make the structure of the optical system compact, the HUD optical system adopts an off-axis optical structure, which can effectively fold the optical path; but the off-axis optical structure will introduce asymmetric optical imaging aberrations while increasing the difficulty of optical system design and reducing the optical path optimization rate. In addition, due to the differences in the processing standards of structural parts such as the vehicle body structure and reflectors, the imaging effect of the vehicle-mounted HUD will be unstable, increasing the complexity of the tolerance analysis of the vehicle-mounted HUD. The traditional tolerance analysis Monte Carlo method alone is far from meeting the HUD image quality standards and cannot perform a systematic and comprehensive tolerance analysis on the vehicle-mounted HUD. Therefore, a tolerance sensitivity analysis method suitable for vehicle-mounted head-up displays is urgently needed to solve the above-mentioned problems. Summary of the invention

[0003] The present invention provides a tolerance sensitivity analysis method suitable for a vehicle-mounted head-up display. By adjusting the tolerances of the degrees of freedom of each optical component and the entire HUD, the sensitivity of the tolerance parameters to the HUD image quality is obtained. According to the correlation between the tolerances of each degree of freedom and the image quality, a stable imaging tolerance is obtained, thereby solving the current technical problems of poor optical imaging quality, great design difficulty, reduced optical path optimization rate and unstable imaging effect.

[0004] In order to achieve the above technical objectives, the specific technical solutions adopted by the present invention are:

[0005] A tolerance sensitivity analysis method suitable for a vehicle head-up display is provided for tolerance analysis of an optical system of a vehicle head-up display, including:

[0006] S1. Obtain the image quality evaluation result of the vehicle HUD design, and the initial image quality evaluation result of the design meets the HUD design requirements;

[0007] S2. Adjust the degree of freedom tolerance of the optical components and the whole vehicle HUD to obtain the evaluation result of the changed HUD image quality;

[0008] S3. Calculate the image quality evaluation deviation before and after the tolerance of each degree of freedom of the vehicle HUD changes. Under the condition of controlling the variable, change the offset or tilt by the same change value. The larger the image quality deviation is, the more sensitive the degree of freedom tolerance parameter is, and the higher the correlation with the HUD image quality is. On the contrary, the smaller the image quality deviation is, the less sensitive the degree of freedom tolerance parameter is, and the lower the correlation with the HUD image quality is.

[0009] S4, obtaining the sensitivity of the tolerance parameters of each degree of freedom of each optical component and the whole vehicle HUD and the imaging quality of the HUD system, and obtaining the correlation between the tolerance parameters of each degree of freedom and the HUD image quality;

[0010] S5. Obtain the tolerance parameters that significantly affect the HUD imaging quality and allocate HUD tolerances. The higher the sensitivity of the tolerance parameters, the greater the tolerance control, and the more stringent control is required. For low-sensitivity tolerance parameters, the control is relaxed to achieve better HUD imaging effects.

[0011] Furthermore, the initial image quality evaluation result is obtained, and the image quality evaluation includes: field of view (FOV) of the HUD, grid distortion, image tilt, RMS spot diameter, MTF and dynamic distortion.

[0012] Furthermore, the optical components of the vehicle-mounted HUD include a primary reflector, a secondary reflector and a picture generating unit (PGU).

[0013] Furthermore, the degree of freedom tolerance of the HUD optical components and the entire device includes an X-direction offset, a Y-direction offset, a Z-direction offset, an X-direction tilt, a Y-direction tilt, and a Z-direction tilt.

[0014] Furthermore, in step S3, the image quality evaluation deviation is obtained by calculating the difference between the image quality data after the degree of freedom tolerance amount changes and the initial image quality data.

[0015] By adopting the above technical solution, the present invention can also bring the following beneficial effects:

[0016] The present invention provides a tolerance sensitivity analysis method suitable for a vehicle-mounted head-up display, which can comprehensively and completely analyze the correlation between each HUD component and the entire machine and the HUD imaging effect, reasonably allocate tolerances, reduce the design complexity of the HUD optical system, improve the optical path optimization efficiency, and improve the HUD image imaging effect, so that it can better meet industry requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The present invention is a flow chart of a tolerance sensitivity analysis method applicable to a vehicle-mounted head-up display. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0020] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0021] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present invention, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0022] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention. The drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0023] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0024] Example 1

[0025] In one embodiment of the present invention, Figure 1As shown, a tolerance sensitivity analysis method of an off-axis optical system provided by an embodiment of the present invention specifically includes:

[0026] S1. Obtain the image quality evaluation result of the vehicle HUD design, and the initial image quality evaluation result of the design meets the HUD design requirements;

[0027] S2. Adjust the degree of freedom tolerance of the optical components and the whole vehicle HUD to obtain the evaluation result of the changed HUD image quality;

[0028] S3. Calculate the image quality evaluation deviation before and after the tolerance of each degree of freedom of the vehicle HUD changes. Under the condition of controlling the variable, change the offset or tilt by the same change value. The larger the image quality deviation is, the more sensitive the degree of freedom tolerance parameter is, and the higher the correlation with the HUD image quality is. On the contrary, the smaller the image quality deviation is, the less sensitive the degree of freedom tolerance parameter is, and the lower the correlation with the HUD image quality is.

[0029] S4, obtaining the sensitivity of the tolerance parameters of each degree of freedom of each optical component and the whole vehicle HUD and the imaging quality of the HUD system, and obtaining the correlation between the tolerance parameters of each degree of freedom and the HUD image quality;

[0030] S5. Obtain the tolerance parameters that significantly affect the HUD imaging quality and allocate HUD tolerances. The higher the sensitivity of the tolerance parameters, the greater the tolerance control, and the more stringent control is required. For low-sensitivity tolerance parameters, the control is relaxed to achieve better HUD imaging effects.

[0031] The specific implementation steps are as follows:

[0032] 1. Obtain the image quality evaluation results of the vehicle-mounted HUD design through Zemax optical design software and CodeV optical design software, wherein the image quality evaluation results of the vehicle-mounted HUD design include the field of view (FOV), grid distortion, image tilt, RMS spot diameter, MTF, and dynamic distortion of the HUD.

[0033] The size of the field of view determines the field of view of the HUD optical system, and a suitable field of view can achieve better HUD imaging effects; grid distortion indicates the deviation between the actual image height and the paraxial image height of the HUD optical system in different fields of view; image tilt indicates the rotation angle of the HUD displayed image relative to the designed position; RMS spot radius is an important indicator for analyzing optical imaging effects. A series of object points are drawn through the optical system on the actual image surface through calculation. If the RMS spot is small enough, the imaging effect of the HUD optical system will be better; MTF is a function of spatial frequency, and its value is between 0 and 1. The larger the MTF value, the closer the HUD optical system is to the diffraction limit, and the better the imaging quality of the HUD system; dynamic distortion is a dynamic coordinate change caused by the movement of the image as the human eye moves within the eye box, which indicates the stability of HUD imaging during the movement of the human eye.

[0034] In this embodiment, the image quality evaluation result of the field of view of 9°×3° is designed by CodeV optical design software. The image quality evaluation result of HUD is obtained, and the maximum distortion value is 2.82%, the maximum RMS spot radius value is 12.75μm, and MTF>0.6@6l p / mm.

[0035] 2. Adjust the degree of freedom tolerance of the optical components and the entire vehicle HUD, including the following sub-steps:

[0036] Through control variable analysis, the tolerance variation interval and tolerance range are determined.

[0037] Then the tolerances are changed, which are the six degrees of freedom tolerances of the primary reflector, secondary reflector, image generation unit (PGU) optical parts and the whole machine of the vehicle HUD, namely, the X-direction offset, Y-direction offset, Z-direction offset, X-direction tilt, Y-direction tilt and Z-direction tilt.

[0038] In this embodiment, the tolerance parameters of the six degrees of freedom of eccentricity of the secondary reflector in the X, Y, and Z directions and the tilt in the X, Y, and Z directions are changed. The eccentricity tolerance range is [-6mm, 6mm], the eccentricity change interval is 2mm, and the tilt tolerance range is [-2°, 2°], and the tilt angle interval is 0.5°, so as to obtain the image quality evaluation result of the HUD system.

[0039] In this embodiment, the CodeV optical design software is used to simulate and obtain the image quality evaluation data after each change. The specific data are shown in Tables 1 to 6 below:

[0040] Table 1 Analysis results of secondary reflector eccentricity in X direction

[0041]

[0042] Table 2 Analysis results of eccentricity of secondary reflector in Y direction

[0043]

[0044]

[0045] Table 3 Analysis results of secondary reflector eccentricity in Z direction

[0046]

[0047] Table 4 Analysis results of secondary reflector tilt in X direction

[0048]

[0049] Table 5 Analysis results of the secondary reflector tilt in the Y direction

[0050]

[0051] Table 6 Analysis results of the secondary reflector's Z-direction tilt

[0052]

[0053] 3. By calculating the difference between the image quality data after the degree of freedom tolerance changes and the initial image quality data, the image quality evaluation deviation is obtained.

[0054] In this embodiment, the eccentricity tolerance varies within the tolerance range of [-6mm, 6mm]. When the eccentricity of the secondary reflector in the X direction varies within the tolerance range, the maximum deviation rate of image distortion is 10.28%, the maximum deviation rate of the RMS spot radius is 73.49%, and the maximum deviation rate of MTF at a cutoff frequency of 6l p / mm is 15%; when the eccentricity of the secondary reflector in the Y direction varies within the tolerance range, the maximum deviation rate of image distortion is 10.99%, the maximum deviation rate of the RMS spot radius is 136.94%, and the maximum deviation rate of MTF at a cutoff frequency of 6l p / mm is 30%; when the eccentricity of the secondary reflector in the Z direction varies within the tolerance range, the maximum deviation rate of image distortion is 15.96%, the maximum deviation rate of the RMS spot radius is 374.43%, and the maximum deviation rate of MTF at a cutoff frequency of 6l p / mm is 95%.

[0055] The tilt tolerance varies within the tolerance range of [-2°, 2°]. The maximum deviation rate of the distortion of the secondary reflector in the X direction when the tilt angle changes within the tolerance range is 97.52%, the maximum deviation rate of the RMS spot radius is 202.98%, and the maximum deviation rate of the MTF at 6l p / mm is 61.67%; the maximum deviation rate of the distortion of the secondary reflector in the Y direction when the tilt angle changes within the tolerance range is 36.52%, the maximum deviation rate of the RMS spot radius is 137.1%, and the maximum deviation rate of the MTF at 6l p / mm is 18.33%; the maximum deviation rate of the distortion of the secondary reflector in the Z direction when the tilt angle changes within the tolerance range is 14.89%, the maximum deviation rate of the RMS spot radius is 234.35%, and the maximum deviation rate of the MTF at 6l p / mm is 45%.

[0056] 4. Obtain the sensitivity of the tolerance parameters of each degree of freedom of each optical component and the whole vehicle HUD to the imaging quality of the HUD system, and obtain the correlation between each degree of freedom tolerance parameter and the HUD image quality. The change of the difference affects the imaging quality of the HUD. The larger the tolerance value, the worse the image quality. When the offset or tilt is changed by the same change value under the condition of controlling the variable, the larger the image quality deviation is, the more sensitive the degree of freedom tolerance parameter is, and the higher the correlation with the HUD image quality is; conversely, the smaller the image quality deviation is, the less sensitive the degree of freedom tolerance parameter is, and the lower the correlation with the HUD image quality is.

[0057] In this embodiment, since the change of the eccentricity in the Z direction of the secondary reflector will cause the change of the total object distance of the off-axis three-mirror system, which will further affect the imaging effect, as the eccentricity in the Z direction increases, the imaging quality gradually deteriorates and fails to meet the imaging standard. Therefore, within the same tolerance variation range, the sensitivity of the eccentricity in the Z direction of the secondary reflector is higher than the eccentricity in the X and Y directions of the secondary reflector. In addition, according to data analysis, the sensitivity of the tilt tolerance parameter of the secondary reflector element is higher than the eccentricity tolerance parameter.

[0058] 5. Obtain the tolerance parameters that significantly affect the HUD imaging quality, determine the correlation between the tolerance parameters of each degree of freedom of the HUD optical components and the entire machine and the HUD image quality according to the size of the image quality evaluation deviation, and allocate the HUD tolerance.

[0059] According to the correlation between tolerance parameters and HUD image quality, tolerances are reasonably allocated within the tolerance range. The higher the sensitivity of the tolerance parameters, the greater the tolerance control, and the need to tighten the tolerance limits. For low-sensitivity tolerance parameters, the limits can be appropriately relaxed to ensure that the HUD image quality meets the imaging standards.

[0060] Through data analysis, the change of the tolerance of the secondary reflector X eccentricity mainly affects the RMS spot radius. The tolerance range is within ±2mm, which meets the MTF>0.6@6l p / mm, and the image quality meets the imaging standard. Therefore, the tolerance range of the secondary reflector X eccentricity is set to ±2mm; the tolerance of the secondary reflector Y eccentricity has the greatest impact on the RMS spot radius, but it still meets the imaging standard. The sensitivity of the secondary reflector Y eccentricity tolerance is relatively small. Under the imaging condition of MTF>0.6@6l p / mm, the tolerance limit of the secondary reflector Y eccentricity can be appropriately relaxed, and the tolerance range of the secondary reflector Y eccentricity is set to ±3mm; the tolerance change of the secondary curved reflector Z eccentricity of ±2mm cannot meet the imaging condition of MTF>0.6@6l p / mm, so the tolerance limit is tightened, and the control tolerance range is set to ±1mm to meet the imaging standard.

[0061] The X-direction tilt tolerance of the secondary reflector has a greater impact on distortion and RMS spot radius, and the negative direction sensitivity of the X-direction tilt is greater than the positive direction. When the positive tilt angle exceeds 2°, the image is missing, and when the negative tilt exceeds 1°, the image imaging effect is extremely poor. Therefore, the negative direction X tilt sensitivity is greater than the positive direction X tilt. The tolerance limit is tightened, and the negative X tilt tolerance is adjusted to -0.5°, and the X-direction tilt tolerance range is controlled to -0.5°~1°; the Y-direction tilt tolerance of the secondary reflector has a greater impact on distortion and RMS spot radius. As the tolerance value increases, the HUD image quality is gradually deteriorating. The control tolerance range is set to ±1° to meet the imaging standard; the Z-direction tilt tolerance of the secondary reflector has a greater impact on the RMS spot radius and MTF. When the control tolerance range is set to ±1°, the image quality MTF result still does not meet the requirement of >0.6@6l p / mm, and the Z-direction tilt angle tolerance of the secondary reflector is controlled within ±0.5°.

[0062] In short, the present invention can comprehensively and completely analyze the correlation between each HUD component and the whole machine and the HUD imaging effect, reasonably allocate tolerances, reduce the design complexity of the HUD optical system, improve the optical path optimization efficiency, and improve the HUD image imaging effect, so that it can better meet industry requirements.

[0063] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A tolerance sensitivity analysis method suitable for a vehicle head-up display, used for tolerance analysis of the optical system of a vehicle head-up display, characterized in that: include: S1. Obtain the image quality evaluation results of the vehicle HUD design; S2. Adjust the degree of freedom tolerance of the optical components and the whole vehicle HUD to obtain the evaluation result of the changed HUD image quality; S3. Calculate the image quality evaluation deviation before and after the tolerance of each degree of freedom of the vehicle HUD changes. Under the condition of controlling the variable, change the offset or tilt by the same change value. The larger the image quality deviation is, the more sensitive the degree of freedom tolerance parameter is, and the higher the correlation with the HUD image quality is. On the contrary, the smaller the image quality deviation is, the less sensitive the varying degree of freedom tolerance parameter is and the lower the correlation with the HUD image quality is; S4, obtaining the sensitivity of the tolerance parameters of each degree of freedom of each optical component and the whole vehicle HUD and the imaging quality of the HUD system, and obtaining the correlation between the tolerance parameters of each degree of freedom and the HUD image quality; S5. Obtain the tolerance parameters that significantly affect the HUD imaging quality and allocate HUD tolerances. The higher the sensitivity of the tolerance parameters, the greater the tolerance control, and the more stringent control is required. For low-sensitivity tolerance parameters, the control is relaxed to achieve better HUD imaging effects.

2. A tolerance sensitivity analysis method applicable to a vehicle head-up display according to claim 1, characterized in that: Obtain initial image quality evaluation results, including: HUD field of view (FOV), grid distortion, image tilt, RMS spot diameter, MTF, and dynamic distortion.

3. The tolerance sensitivity analysis method for a vehicle head-up display according to claim 2, characterized in that: The optical components of the vehicle-mounted HUD include a primary reflector, a secondary reflector and a picture generation unit (PGU).

4. The tolerance sensitivity analysis method for a vehicle head-up display according to claim 3, characterized in that: The degree of freedom tolerance of HUD optical components and the entire device includes X-direction offset, Y-direction offset, Z-direction offset, X-direction tilt, Y-direction tilt and Z-direction tilt.

5. The tolerance sensitivity analysis method for a vehicle head-up display according to claim 4, characterized in that: In step S3, the image quality evaluation deviation is obtained by calculating the difference between the image quality data after the degree of freedom tolerance amount changes and the initial image quality data.

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