HUD system free-form surface type processing PV deviation model construction method and HUD system free-form surface type processing PV deviation model

Abstract

The invention provides an HUD system free-form surface type processing PV deviation model construction method and a model, and the construction method comprises the steps: testing an existing HUD free-form surface type, obtaining the phase distribution of the surface type, and converting the phase distribution into the height deviation of the surface type; drawing a cloud picture of height deviation of the surface type, observing space distribution of errors, and analyzing variation trends of the errors in different areas; determining a basic matrix e of the PV deviation model according to the variation trend of the error in different regions; and based on the basic matrix e, superposing the deviation epsilon and the random disturbance delta in the optical axis direction to obtain a final HUD system PV deviation model. The PV deviation model constructed by the invention can accurately capture distribution characteristics of free-form surface processing errors, facilitates analysis of error trends and regional characteristics, comprehensively considers multi-factor error sources, improves the accuracy of the model, reduces optical distortion, optimizes the imaging quality, and significantly improves the optical performance and production efficiency of the system.

Description

Technical Field

[0001] This application belongs to the technical field of optical modules for in-vehicle head-up display systems, and particularly relates to a method and model for constructing a PV deviation model for the free-form surface machining of an HUD system. Background Art

[0002] In the inspection of free-form surfaces, constructing a machining error model (MEM) to guide the adaptive distribution of sampling points is an effective method to optimize the inspection process and improve inspection efficiency. MEM describes the possibility of large deviations in different regions of the workpiece surface, thus helping to determine which regions require denser sampling. For a head-up display (HUD) system, the geometric characteristics of free-form surfaces are usually not symmetric, which can cause factors such as rotational distortion, astigmatism, field curvature, and moiré patterns in the virtual image plane of the system, affecting the imaging quality. Therefore, when constructing MEM, the influence of these asymmetric errors on imaging quality needs to be considered. In addition, MEM is mainly applicable to free-form surfaces in cutting machining, and may not be applicable to the analysis of machining error of non-cutting free-form surfaces such as injection molding. The error characteristics caused by different machining methods vary greatly, and if the points with sudden changes in machining error are too dense, it may exceed the processing capacity of the HUD system, resulting in low inspection efficiency. In the prior art, error analysis models mostly use Zernike polynomials or random matrices, which bring factors such as rotational distortion, astigmatism, field curvature, and moiré patterns affecting the imaging quality to the image plane of the HUD system. The second derivative of the average curvature in the central region of the free-form surface is large, which will cause large fluctuations in machining error and increase the inspection difficulty. Summary of the Invention

[0003] Aiming at the defects of the above-mentioned prior art, this application provides a method and model for constructing a PV deviation model for the free-form surface machining of an HUD system. By summarizing the geometric characteristics of the surface shape error changes of the free-form surface of the production HUD according to industry experience and actual inspection, a machining error model library is established, and the type of machining error model is selected according to different requirements. Further, by controlling the machining error model, the occurrence of random errors is avoided, the simulated free-form surface shape is associated with the HUD system, and the influence of the free-form surface machining error on the system is comprehensively analyzed.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] In the first aspect, the present invention proposes a method for constructing a PV deviation model for the free-form surface machining of an HUD system, and the construction method includes:

[0006] S1: Test the existing free-form surface shape of the HUD to obtain the phase distribution of the surface shape and convert it into the height deviation of the surface shape;

[0007] S2: Draw a cloud map of the height deviation of the surface shape, observe the spatial distribution of the error, and analyze the changing trend of the error in different regions;

[0008] S3: Determine the fundamental matrix e of the PV deviation model according to the changing trend of the error in different regions;

[0009] S4: Based on the fundamental matrix e, superimpose the deviation ε in the optical axis direction and the random perturbation δ to obtain the final PV deviation model of the HUD system.

[0010] The method for constructing the PV deviation model of the free-form surface of the HUD system described in this application can accurately capture the distribution characteristics of the free-form surface machining error, facilitate the analysis of the error trend and regional characteristics, comprehensively consider the multi-factor error sources, improve the accuracy of the model, reduce optical distortion, optimize the imaging quality. This method can play an important role in the design and machining of the free-form surface of the HUD system, significantly improving the optical performance and production efficiency of the system.

[0011] Among them, in the step S1 of testing the existing free-form surface of the HUD, it further includes:

[0012] Use interferometric measurement, point diffraction interferometry, and digital holography to test the existing free-form surface of the HUD. Place the free-form surface of the HUD in the interferometer, adjust the interferometer to align the reference optical path with the test surface shape, collect the interference fringe pattern, and analyze the interference fringe pattern to obtain the phase distribution of the surface shape.

[0013] According to different fundamental models e[m×n], nine PV deviation models are built, and the specific situations are as follows:

[0014] In the preferred case 1, in the step S3 of determining the fundamental matrix e of the PV deviation model according to the changing trend of the error in different regions, specifically:

[0015] When the changing trend of the error in different regions is: the error in the middle is smaller, and the error at the four corners is the largest, showing a decreasing or increasing N-shaped or U-shaped surface shape, select an elliptic paraboloid as the PV deviation model for the N-shaped or U-shaped surface shape, and the fundamental matrix e is:

[0016]

[0017] Among them, N / U_e is the fundamental matrix e of the PV deviation model for the N-shaped or U-shaped surface shape, and a, b are arbitrary positive constants. By controlling the values of a and b, the increasing or decreasing degree of the PV deviation in the X and Y directions can be controlled.

[0018] In the preferred case 2, in the step S3 of determining the fundamental matrix e of the PV deviation model according to the changing trend of the error in different regions, specifically:

[0019] When the error variation trends in different regions are: the error distribution is symmetrical around the center and has the characteristics of peaks W and valleys M, and the error shows periodic changes in the radial direction; or the error distribution fluctuates in the X or Y direction, but is relatively stable in other directions;

[0020] Then the basic matrix e is:

[0021] Center rotation symmetry W / M type:

[0022]

[0023] X-direction wave W / M type:

[0024]

[0025] Y-direction wave W / M type:

[0026]

[0027] Among them, Δ is a monotonically increasing or decreasing interval, which is used to control the fluctuation frequency of PV deviation.

[0028] In the preferred scenario 3, in step S3, the basic matrix e of the PV deviation model is determined according to the variation trend of the error in different regions, specifically:

[0029] When the error changes in different areas, the error distribution is a parabolic change in one direction, and the cylindrical surface shape remains unchanged in the direction perpendicular to it.

[0030] Then the basic matrix e is:

[0031] Cylindrical PV deviation X-direction fluctuation:

[0032] C_e=αx 2 ;

[0033] Cylindrical PV deviation Y-direction fluctuation:

[0034] C_e=αy 2 ;

[0035] Among them, C_e is the vector height value of the basic matrix e of the cylindrical PV deviation model, and α is the coefficient of the quadratic term, which represents the trend of surface change.

[0036] In the preferred scenario 4, in step S3, the basic matrix e of the PV deviation model is determined according to the variation trend of the error in different regions, specifically:

[0037] When the error variation trend in different regions is: the error distribution is a hyperbolic paraboloid, the center deviation is small, and the horizontal and vertical directions have opposite variation trends. The basic matrix e is:

[0038]

[0039] In the formula, \(H_e\) is the vector height value of the basic matrix of the saddle-shaped PV deviation model. In the formula, \(a\) and \(b\) are constants, and the increasing or decreasing degree of the PV deviation in the X and Y directions is controlled by controlling the values of \(a\) and \(b\).

[0040] In the preferred case 5, the basic matrix \(e\) of the PV deviation model is determined according to the change trend of the error in different regions in step S3, specifically as follows:

[0041] When the change trend of the error in different regions is that the error distribution is an array type formed by an array distribution based on a cosine function, the basic matrix \(e\) obtained is:

[0042]

[0043] \(A_e\) is the vector height value of the basic matrix of the array-type PV deviation model. In the formula, \(a\) and \(b\) are constants, and the amplitude fluctuation of the PV deviation in the X and Y directions is controlled by controlling the values of \(a\) and \(b\).

[0044] This application gives the above-mentioned cases 1-4, lists 9 cases of the free-form surface types of the HUD, and gives different PV deviation model designs of the HUD system. It covers the error distribution cases from simple to complex.

[0045] Preferably, in this application, the deviation \(\epsilon\) is equal to 0.3 to 0.4 times \(pv\times E[m\times n]\), and \(E\) is the identity matrix.

[0046] In a second aspect, the present invention also provides a PV deviation model for machining the free-form surface type of a HUD system, which is a model obtained by using the method for constructing a PV deviation model for machining the free-form surface type of a HUD system as described in the first aspect.

[0047] In a third aspect, the present invention also provides a method for evaluating the PV deviation of machining the free-form surface type of a HUD system. The evaluation method includes:

[0048] SS1: Create a free-form surface type design of the HUD system in an optical software to obtain a vector height data matrix of the surface type created by the optical software;

[0049] SS2: Superimpose the surface type vector height data and the constructed PV deviation model for machining the free-form surface type of the HUD system to construct the machined free-form surface type;

[0050] SS3: Perform optical performance analysis on the machined free-form surface type to obtain the qualified type and allowable range of the surface type machining error;

[0051] SS4: Generate an evaluation report.

[0052] By simulating the influence of machining errors on optical performance, the present invention accurately evaluates the qualified standard of surface machining, provides a basis for quality control in the production process, ensures that the machined surface meets the design requirements, balances the machining cost and optical performance by setting a reasonable error tolerance range, and provides feedback for free-form surface design to optimize the design to reduce the influence of machining errors. Through this method, the influence of the machining error of the free-form surface of the HUD system on the optical performance can be effectively evaluated, thereby guiding production and design optimization.

[0053] Compared with the prior art, the beneficial effects of the present application are as follows:

[0054] The present application provides a method and model for constructing a PV deviation model of the free-form surface of a HUD system, provides 9 different PV deviation models, can discover and correct potential free-form surface machining problems in the design stage, and the amplitude and fluctuation frequency of the present PV deviation model are controllable. Through the preview of the machining process by 9 different PV deviation models, the final effect after machining the free-form surface can be predicted and evaluated, improving production efficiency and reducing the scrap rate.

[0055] Among them, the main innovation point of the present application is that different from the existing error analysis models which mostly use Zernike polynomials or random matrices, combined with the geometric characteristics of the actual error variation of the free-form surface mirror of the HUD, summarize it, establish a machining error model library, and select the type of machining error model according to different needs. Control the machining error model to avoid the occurrence of random errors, screen out irregular and non-periodic models, reduce the number of trial and error times in the machining process, associate the simulated free-form surface with the HUD system, comprehensively analyze the influence of the free-form surface machining error on the system, and evaluate it with MTF. The machining error model of the present invention controls the error in the central region within ±10μm to ensure the imaging quality in the central region, and the error at the four corners or both sides is the largest to ensure the qualified imaging in the effective region of the free-form surface mirror. Description of the Drawings

[0056] Figure 1 It is a flowchart of a method for constructing a PV deviation model of the free-form surface of a HUD system in an embodiment.

[0057] Figure 2 It is a PV deviation model diagram of an N-type surface or a U-type surface in an embodiment.

[0058] Figure 3 It is a PV deviation model diagram of a centrally rotationally symmetric W / M type in an embodiment.

[0059] Figure 4 It is a PV deviation model diagram of a unidirectional fluctuation W / M type in an embodiment.

[0060] Figure 5 It is the PV deviation model diagram of the cylindrical surface type in an embodiment.

[0061] Figure 6 It is the PV deviation model diagram of the saddle surface type in an embodiment.

[0062] Figure 7 It is the PV deviation model diagram of the array type in an embodiment.

[0063] Figure 8 It is the flowchart of the PV deviation evaluation method for the free-form surface machining of an HUD system in an embodiment. Specific embodiments

[0064] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of them. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0065] Embodiment 1, as Figure 1 shown, the present invention proposes a method for constructing a PV deviation model for the free-form surface machining of an HUD system, and the construction method includes:

[0066] S1: Test the existing free-form surface of the HUD to obtain the phase distribution of the surface, and convert it into the height deviation of the surface;

[0067] S2: Draw a cloud map of the height deviation of the surface, observe the spatial distribution of the error, and analyze the change trend of the error in different regions;

[0068] S3: Determine the basic matrix e of the PV deviation model according to the change trend of the error in different regions;

[0069] S4: Based on the basic matrix e, superimpose the deviation ε in the optical axis direction and the random perturbation δ to obtain the final PV deviation model of the HUD system.

[0070] The method for constructing a PV deviation model for the free-form surface machining of the HUD system described in the present application can accurately capture the distribution characteristics of the free-form surface machining error, facilitate the analysis of the error trend and regional characteristics, comprehensively consider the multi-factor error sources, improve the accuracy of the model, reduce optical distortion, optimize the imaging quality, and this method can play an important role in the free-form surface design and machining of the HUD system, significantly improving the optical performance and production efficiency of the system.

[0071] Among them, testing the existing free-form surface of the HUD in step S1 further includes:

[0072] The existing free-form surface of the HUD is tested by interferometry, point diffraction interferometry, and digital holography. The free-form surface of the HUD is placed in the interferometer, the interferometer is adjusted to align the reference optical path with the test surface, the interference fringe pattern is collected, and the phase distribution of the surface is obtained by analyzing the interference fringe pattern.

[0073] Nine PV deviation models are built according to different basic models e[m×n], and the specific situations are as follows:

[0074] In the preferred case 1, the basic matrix e of the PV deviation model is determined according to the change trend of the error in different regions in step S3, specifically as follows:

[0075] As Figure 2 shown, when the change trend of the error in different regions is: the error in the middle is smaller, and the error at the four corners is the largest, showing a decreasing or increasing N-shaped or U-shaped free-form surface, an elliptic paraboloid is selected as the PV deviation model of the N-shaped or U-shaped free-form surface, and the basic matrix e is:

[0076]

[0077] Among them, N / U_e is the basic matrix e of the PV deviation model of the N-shaped or U-shaped free-form surface, and a and b are arbitrary positive constants. By controlling the values of a and b, the increasing or decreasing degree of the PV deviation in the X and Y directions can be controlled. A larger value of a will make the error change in the X direction more significant; a larger value of b will make the error change in the Y direction more significant.

[0078] Among them, for the N-shaped free-form surface: the error in the middle is small, the error at the four corners is large, showing an increasing trend.

[0079] For the U-shaped free-form surface: the error in the middle is small, the error at the four corners is large, showing a decreasing trend.

[0080] The above PV deviation model is applicable to the situation where the error is smaller in the central region and gradually increases towards the periphery, such as the N-shaped or U-shaped free-form surface.

[0081] In the preferred case 2, the basic matrix e of the PV deviation model is determined according to the change trend of the error in different regions in step S3, specifically as follows:

[0082] When the change trend of the error in different regions is: as Figure 3 shown, the error distribution is symmetric about the center, and has the characteristics of wave peaks W and wave valleys M, and the error shows periodic changes in the radial direction; or as Figure 4 shown, the error distribution shows fluctuations in the X direction or the Y direction, and is relatively stable in other directions;

[0083] Then the basic matrix e is:

[0084] Centrally rotationally symmetric W / M type (the error is symmetric about the center and has the characteristics of wave crest W and wave trough M):

[0085]

[0086] W / M type of fluctuation in the X direction (the error fluctuates in the X direction and is relatively stable in the Y direction):

[0087]

[0088] W / M type of fluctuation in the Y direction (the error fluctuates in the Y direction and is relatively stable in the X direction):

[0089]

[0090] Wherein, Δ is a monotonically increasing or decreasing interval, which is used to control the fluctuation frequency of the PV deviation.

[0091] The above model is applicable to various error distribution patterns such as the centrally rotationally symmetric W / M type, the W / M type of fluctuation in the X direction, and the W / M type of fluctuation in the Y direction.

[0092] In the preferred case 3, in step S3, the basis matrix e of the PV deviation model is determined according to the change trend of the error in different regions, specifically:

[0093] As Figure 5 shown, when the change trend of the error in different regions is that the error distribution is a cylindrical surface type with a one-way parabolic change and the direction perpendicular to it remains unchanged, it is applicable to the error distribution with a one-way parabolic change, especially the error evaluation of the cylindrical surface type.

[0094] Then the basis matrix e is:

[0095] Cylindrical PV deviation with fluctuation in the X direction (the error changes parabolically in the X direction and remains unchanged in the Y direction):

[0096] C_e = αx 2 ;

[0097] Cylindrical PV deviation with fluctuation in the Y direction (the error changes parabolically in the Y direction and remains unchanged in the X direction):

[0098] C_e = αy 2 ;

[0099] Wherein, C_e is the sag value of the basis matrix e of the cylindrical PV deviation model, and α in the formula is the quadratic coefficient, which represents the change trend of the surface.

[0100] In the preferred case 4, in step S3, the basis matrix e of the PV deviation model is determined according to the change trend of the error in different regions, specifically:

[0101] As Figure 6 shown, when the change trend of the error in different regions is: the error distribution is a hyperbolic paraboloid, with a small central deviation and a saddle-shaped surface where the change trends in the horizontal and vertical directions are opposite, which is suitable for scenarios that need to simulate the saddle-shaped error distribution, such as the free-form surface error analysis in an optical system or the design optimization of an HUD system. Then the fundamental matrix e is obtained as follows:

[0102]

[0103] In the formula, H_e is the sag value of the fundamental matrix of the saddle-shaped PV deviation model. In the formula, a and b are constants, and the increasing or decreasing degrees of the PV deviation in the X and Y directions are controlled by controlling the values of a and b.

[0104] In the preferred case 5, in step S3, the fundamental matrix e of the PV deviation model is determined according to the change trend of the error in different regions, specifically:

[0105] As Figure 7 shown, when the change trend of the error in different regions is: the error distribution is an array type formed by an array distribution based on a cosine function, then the fundamental matrix e is obtained as follows:

[0106]

[0107] A_e is the sag value of the fundamental matrix of the array-type PV deviation model. In the formula, a and b are constants, and the amplitude fluctuations of the PV deviation in the X and Y directions are controlled by controlling the values of a and b.

[0108] This application gives the above-mentioned cases 1-4, lists 9 cases of the free-form surface types of the HUD, and gives different PV deviation model designs for the HUD system. It covers the error distribution cases from simple to complex.

[0109] Preferably, in this application, the deviation ε is equal to 0.3 to 0.4 times pv*E[m×n], where E is the identity matrix.

[0110] In the second embodiment, the present invention also provides a PV deviation model for the free-form surface type machining of an HUD system, which is a model obtained by using the method for constructing a PV deviation model for the free-form surface type machining of an HUD system as described in the first aspect. This model can accurately describe the possible PV deviations in the process of free-form surface type machining of the HUD system and provides various fundamental matrix forms to adapt to different error distribution trends.

[0111] In this embodiment, according to the change trend of the error in different regions, the basic matrix e of the corresponding PV deviation model is determined. Among them, the basic matrix e covers various error distribution types such as central rotationally symmetric W / M type, X-direction fluctuating W / M type, Y-direction fluctuating W / M type, cylindrical PV deviation, and saddle-shaped PV deviation. By using the PV deviation model for the free-form surface machining of the HUD system provided by the present invention, the error in the machining process can be understood and controlled more accurately, thereby improving the overall performance and reliability of the HUD system.

[0112] Embodiment 3, as Figure 8 shown, the present invention also provides a method for evaluating the PV deviation of the free-form surface machining of the HUD system. The evaluation method includes:

[0113] SS1: Create a free-form surface design of the HUD system in optical software to obtain the surface sag data matrix sag[m×n] created by the optical software;

[0114] SS2: Superimpose the surface sag data and the established PV deviation model for the free-form surface machining of the HUD system to construct the machined free-form surface for subsequent optical performance analysis; among them, the PV deviation model selects an appropriate basic matrix e according to the error distribution characteristics, such as central rotationally symmetric W / M type, X-direction fluctuating W / M type, Y-direction fluctuating W / M type, cylindrical PV deviation, saddle-shaped PV deviation, etc.

[0115] SS3: Perform optical performance analysis on the machined free-form surface to obtain the qualified type and allowable range of the surface machining error;

[0116] SS4: Generate an evaluation report.

[0117] Preferably, in SS2: Superimpose the surface sag data and the established PV deviation model for the free-form surface machining of the HUD system, specifically:

[0118] surf_sag[m×n] = sag[m×n] + PV[m×n];

[0119] wherein, sag[m×n] is the surface sag data matrix; PV[m×n] is the PV deviation model.

[0120] Preferably, in SS3: Perform optical performance analysis on the machined free-form surface, specifically including: analysis in multiple dimensions such as wavefront error, ray tracing, imaging quality (such as MTF, PSF, etc.), and optical distortion.

[0121] Preferably, the generated evaluation report at least includes: the sag data of the processed free-form surface; the analysis results of optical performance (such as wavefront error, imaging quality, etc.); the qualified types and allowable ranges of errors; the main distribution characteristics and sources of errors; optimization suggestions (such as adjusting processing parameters, selecting a more suitable PV deviation model, etc.) and other aspects of analysis content, so as to provide to relevant technical personnel or decision-makers for further optimizing the design and processing technology of the HUD system.

[0122] The present invention accurately evaluates the qualified standard of surface processing by simulating the influence of processing errors on optical performance, provides a basis for quality control in the production process, ensures that the processed surface meets the design requirements, balances the processing cost and optical performance by setting a reasonable error allowable range, and at the same time provides feedback for free-form surface design to optimize the design to reduce the influence of processing errors. By this method, the influence of the processing errors of the free-form surface of the HUD system on optical performance can be effectively evaluated, thereby guiding production and design optimization.

[0123] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application. Those of ordinary skill in the art can make various changes and modifications therein without departing from the scope and spirit of the present application. All such changes and modifications are intended to be included within the scope of the present application as claimed in the appended claims.

[0124] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the element.

[0125] Although the description of the present application is made in conjunction with the above specific embodiments, it is obvious that those skilled in the art can make many substitutions, modifications and changes based on the above content. Therefore, all such substitutions, modifications and changes are included within the spirit and scope of the appended claims.

Claims

1. A method for constructing a PV deviation model for free-form surface processing of a HUD system, characterized in that: The construction method comprises: S1: Test the existing HUD free-form surface, obtain the phase distribution of the surface, and convert it into the height deviation of the surface; S2: Draw a cloud map of the height deviation of the surface, observe the spatial distribution of the error, and analyze the changing trend of the error in different areas; S3: Determine the basic matrix e of the PV deviation model according to the changing trend of the error in different regions; S4: Based on the basic matrix e, its deviation ε in the optical axis direction and the random disturbance δ are superimposed to obtain the final HUD system PV deviation model.

2. The method for constructing a PV deviation model for free-form surface processing of a HUD system according to claim 1, characterized in that: Testing the existing HUD free-form surface shape in step S1 also includes: using interferometry, point diffraction interferometry, and digital holography to test the existing HUD free-form surface shape, placing the free-form surface shape of the HUD in an interferometer, adjusting the interferometer to align the reference optical path with the test surface shape, collecting an interference fringe pattern, and analyzing the interference fringe pattern to obtain a phase distribution of the surface shape.

3. The method for constructing a PV deviation model for free-form surface processing of a HUD system according to claim 1, characterized in that: In step S3, the basic matrix e of the PV deviation model is determined according to the variation trend of the error in different regions, specifically: When the error variation trend in different areas is: the middle error is small, and the four corner errors are the largest, the decreasing or increasing N-shaped surface type or U-shaped surface type, the elliptical paraboloid is selected as the PV deviation model of the N-shaped surface type or the U-shaped surface type, and the basic matrix e is obtained as: Among them, N / U_e is the basic matrix e of the PV deviation model of the N-shaped surface or the U-shaped surface, a and b are arbitrary positive constants, and the degree of increase or decrease of the PV deviation in the X and Y directions can be controlled by controlling the values ​​of a and b.

4. The method for constructing a PV deviation model for free-form surface processing of a HUD system according to claim 1, characterized in that: In step S3, the basic matrix e of the PV deviation model is determined according to the variation trend of the error in different regions, specifically: When the error variation trends in different regions are: the error distribution is symmetrical around the center and has the characteristics of peaks W and valleys M, and the error shows periodic changes in the radial direction; or the error distribution fluctuates in the X or Y direction, but is relatively stable in other directions; Then the basic matrix e is: Center rotation symmetry W / M type: X-direction wave W / M type: Y-direction wave W / M type: Among them, Δ is a monotonically increasing or decreasing interval, which is used to control the fluctuation frequency of PV deviation.

5. The method for constructing a PV deviation model for free-form surface processing of a HUD system according to claim 1, characterized in that: In step S3, the basic matrix e of the PV deviation model is determined according to the variation trend of the error in different regions, specifically: When the error changes in different areas, the error distribution is a parabolic change in one direction, and the cylindrical surface shape remains unchanged in the direction perpendicular to it. Then the basic matrix e is: Cylindrical PV deviation X-direction fluctuation: C_e=αx 2 ; Cylindrical PV deviation Y-direction fluctuation: C_e=αy 2 ; Among them, C_e is the vector height value of the basic matrix e of the cylindrical PV deviation model, and α is the coefficient of the quadratic term, which represents the trend of surface change.

6. The method for constructing a PV deviation model for free-form surface processing of a HUD system according to claim 1, characterized in that: In step S3, the basic matrix e of the PV deviation model is determined according to the variation trend of the error in different regions, specifically: When the error variation trend in different regions is: the error distribution is a hyperbolic paraboloid, the center deviation is small, and the horizontal and vertical directions have opposite variation trends. The basic matrix e is: Where H_e is the basic matrix vector height value of the saddle surface PV deviation model, and a and b are constants. The degree of increase or decrease of the PV deviation in the X and Y directions can be controlled by controlling the values ​​of a and b.

7. The method for constructing a PV deviation model for free-form surface processing of a HUD system according to claim 1, characterized in that: In step S3, the basic matrix e of the PV deviation model is determined according to the variation trend of the error in different regions, specifically: When the error variation trend in different regions is: the error distribution is an array type composed of array distribution based on cosine function, then the basic matrix e is: A_e is the vector height value of the basic matrix of the array PV deviation model, where a and b are constants. The amplitude fluctuation of the PV deviation in the X and Y directions can be controlled by controlling the values ​​of a and b.

8. The method for constructing a PV deviation model for free-form surface processing of a HUD system according to claim 1, characterized in that: The deviation ε is equal to 0.3 to 0.4 times pv multiplied by E[m×n], where E is the unit matrix.

9. A PV deviation model for free-form surface processing of a HUD system, characterized in that: The HUD system free-form surface processing PV deviation model is a model obtained by using a HUD system free-form surface processing PV deviation model construction method according to any one of claims 1 to 6.

10. A method for evaluating the PV deviation model of free-form surface processing of a HUD system according to claim 7, characterized in that: The evaluation methods include: SS1: Create a free-form surface design of the HUD system in the optical software and obtain the surface sag data matrix created by the optical software; SS2: superimposing the surface elevation data and the constructed HUD system free-form surface processing PV deviation model to construct the processed free-form surface shape; SS3: performing optical performance analysis on the free-form surface after processing to obtain the qualified type and allowable range of the surface processing error; SS4: Generate an assessment report.

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