A design method for a flexible hinge supporting a large-aperture optical telescope

Abstract

This invention provides a design method for a flexible hinge supporting a large-aperture optical telescope. The method involves parametric processing of the flexible hinge structure in a CAD model, establishing a finite element model of the primary mirror and supporting structure assembled with the initial flexible hinge structure; setting multiple working conditions to obtain nodal displacement data; and acquiring the rigid body displacement and surface RMS values ​​of the primary mirror through numerical fitting. An automated workflow is established to iteratively generate a mathematical substitution model; based on the mathematical substitution model, target values ​​are iteratively calculated, and the output target values ​​are evaluated to select the optimal structural parameter target values ​​as the dimensional parameters of the flexible hinge structure. The design method proposed in this invention has the advantages of being faster and more accurate, significantly saving computation time and labor costs. Compared with traditional optimization methods that focus on deformation and stress, it has a more direct and mechanical advantage, more accurately and comprehensively reflecting the working state of the structure, thus obtaining better optimization results.

Description

Technical Field

[0001] This invention relates to the field of optical-mechanical optimization design technology, and in particular to a design method for a flexible hinge supporting a large-aperture optical telescope. Background Technology

[0002] With the rapid development of space technology, large-aperture primary mirrors, as a key component of the optical system of space cameras, must meet the system's requirements for their mechanical structure and optical performance. The larger the telescope's aperture, the lower the manufacturing precision of the primary mirror, and the greater the impact of the primary mirror support on the mirror's surface shape, thus affecting the imaging quality of the optical system. To meet the surface shape requirements of the primary mirror structure, large-aperture primary mirrors generally employ flexible supports, and flexible hinges are an indispensable component of these supports.

[0003] Flexible hinges are a special type of kinematic pair that utilizes material deformation to generate displacement. They are used to provide finite angular displacement for complex movements around an axis and offer advantages such as zero mechanical friction, zero backlash, easy maintenance, high resolution, and the ability to be manufactured in a single piece. Precision pointing mechanisms connected by flexible hinges have wide applications in future optical systems, semiconductor manufacturing, and ultra-precision engineering fields such as space exploration.

[0004] Currently, there are many theoretical design methods for flexible hinges. However, in practical design, these methods still encounter many difficulties. Traditional flexible hinge design methods mainly rely on the designer's experience to determine the hinge configuration, which is very simple, usually just different shaped cutouts. In this case, the performance of the flexible hinge largely depends on the designer's experience, making it difficult to design flexible hinges with complex configurations and superior performance. Summary of the Invention

[0005] To address the problems existing in the prior art, a design method for a flexible hinge supporting a large-aperture optical telescope is provided. By using a multi-objective optimization method to optimize the parameters of the flexible hinge structure based on the mirror surface shape and rigid body displacement, efficiency and cost can be effectively improved.

[0006] The technical solution adopted in this invention is as follows: A design method for a flexible hinge supporting a large-aperture optical telescope, comprising:

[0007] Step 1: Use the typical elliptical notch flexible hinge profile as the initial flexible hinge structure, and parametrically process the structural dimension parameters in the CAD model.

[0008] Step 2: Establish a finite element model of the main mirror and support structure equipped with the initial flexible hinge structure, and use the structural dimension parameters of the initial flexible hinge structure as parameter variables;

[0009] Step 3: Set up multiple calculation conditions and use a finite element solver to solve the finite element model to obtain the deformation, stress and nodal displacement data of the flexible hinge structure and the main mirror surface.

[0010] Step 4: Use the nodal displacement data as input and fit the input data into mirror Zernike coefficients and primary mirror rigid body displacement and surface RMS values ​​using numerical fitting software.

[0011] Step 5: Integrate steps 1-4 into an automated workflow. Use a multi-objective optimization algorithm to combine the structural parameter variables of the flexible hinge as input samples, and set the upper and lower limits of each variable and the step size of the size change during iteration. Solve the flexible hinge stress and the response of the primary mirror rigid body displacement and surface RMS value through an integrated automated simulation calculation process as output samples. Use the obtained sample set to construct a mathematical substitution model of the flexible hinge structure design variables, stress, primary mirror displacement and deformation response.

[0012] Step 6: Iteratively update the structural parameter variables of the flexible hinge based on the multi-objective optimization algorithm, set the constraints of the variables, continuously select new combinations of variables and substitute them into the mathematical substitution model to calculate the target value until the maximum number of iterations is reached, evaluate all the response output target values, and select the optimal structural parameter target value as the size parameter of the flexible hinge structure.

[0013] Furthermore, the initial flexible hinge structure in step 1 is: two sets of mutually orthogonal elliptical cuts are symmetrically designed on the flexible structure.

[0014] Furthermore, in step 1, the structural dimensional parameters include:

[0015] The vertical cut dimensions and position parameters of the initial flexible hinge structure include: major axis a1, minor axis b1, plane cut height c1, cut position L1, thickness h1, and internal tilt angle k of the flexible hinge.

[0016] The horizontal cut dimensions and position parameters of the initial flexible hinge structure include: major axis a2, minor axis b2, plane cut height c2, cut position L2, and thickness h2;

[0017] The flexible hinge has a symmetrical structure, and the cut dimensions and position parameters on both sides adopt uniform parameters.

[0018] Furthermore, in step 3, the working conditions include those that are of particular concern to the shape of the main mirror surface, including gravity deformation working conditions and thermal deformation working conditions.

[0019] Furthermore, in step 5, the size change step size is 0.5 mm and the angle change step size is 5° during iteration.

[0020] Furthermore, in step 6, the constraints include structural dimension constraints and flexible hinge stress constraints; wherein the structural dimension constraints include: b1+c1

[0021] Furthermore, in step 6, the evaluation method is as follows: the rigid body displacement and surface shape RMS of the primary mirror are weighted according to the magnitude of their influence on imaging and used as the evaluation function to evaluate all response output target values.

[0022] Furthermore, the gravity deformation conditions include gravity deformation conditions with tilt angles of 0°, 15°, and 30°.

[0023] Furthermore, the heat deformation conditions include heat deformation conditions at high temperature (60°C) and low temperature (30°C).

[0024] Compared with existing technologies, the beneficial effects of adopting the above technical solution are as follows:

[0025] 1. This invention employs computer-automated optimization technology, which is faster and more accurate than the more common manual modification of structural parameters and simulation fitting, greatly saving computation time and labor costs.

[0026] 2. This invention iteratively optimizes the hinge parameters based on the surface shape of the mirror and the rigid body displacement, which has the advantage of being more directly aligned with optical mechanics than the traditional optimization based on deformation and stress.

[0027] 3. This invention considers multiple working conditions simultaneously during optimization, including gravity at different angles and thermal deformation, which can more accurately and comprehensively reflect the working state of the structure, thereby obtaining better optimization results. Attached Figure Description

[0028] Figure 1 This is a flowchart of the design method proposed in this invention.

[0029] Figure 2 This is a schematic diagram of the vertical structure of a flexible hinge in one embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the horizontal structure of a flexible hinge in one embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of the flexible hinge installation in one embodiment of the present invention. Detailed Implementation

[0032] ​The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar modules or modules having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, the embodiments of this application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0033] To design flexible hinges with complex configurations and superior performance, this embodiment proposes a design method for flexible hinges based on a multi-objective optimization approach. This method offers advantages such as faster and more accurate design, while also considering various operating conditions, including gravity at different angles and thermal deformation. This allows for a more accurate and comprehensive reflection of the structure's working state, resulting in better optimization results. The specific scheme is as follows:

[0034] like Figure 1 As shown, a design method for a flexible hinge supporting a large-aperture optical telescope includes:

[0035] Step 1: Use the typical elliptical notch flexible hinge profile as the initial flexible hinge structure, and parametrically process the structural dimension parameters in the CAD model.

[0036] Step 2: Establish a finite element model of the main mirror and support structure equipped with the initial flexible hinge structure, and use the structural dimension parameters of the initial flexible hinge structure as parameter variables;

[0037] Step 3: Set up multiple calculation conditions and use a finite element solver to solve the finite element model to obtain the deformation, stress and nodal displacement data of the flexible hinge structure and the main mirror surface.

[0038] Step 4: Use the nodal displacement data as input and fit the input data into mirror Zernike coefficients and primary mirror rigid body displacement and surface RMS values ​​using numerical fitting software.

[0039] Step 5: Integrate steps 1-4 into an automated workflow. Use a multi-objective optimization algorithm to combine the structural parameter variables of the flexible hinge as input samples, and set the upper and lower limits of each variable and the step size of the size change during iteration. Solve the flexible hinge stress and the response of the primary mirror rigid body displacement and surface RMS value through an integrated automated simulation calculation process as output samples. Use the obtained sample set to construct a mathematical substitution model of the flexible hinge structure design variables, stress, primary mirror displacement and deformation response.

[0040] Step 6: Iteratively update the flexible hinge structure parameter variables based on a multi-objective optimization algorithm, and set constraints for the variables. Continuously select new variable combinations and substitute them into the mathematical substitution model to calculate the target value until the maximum number of iterations is reached. Evaluate all response output target values ​​and select the optimal structural parameter target value as the dimensional parameters of the flexible hinge structure. The final designed flexible hinge structure is then installed. Figure 4 As shown.

[0041] Specifically, in step 1, this embodiment establishes a flexible hinge optimization design model. Two sets of mutually orthogonal elliptical cuts are symmetrically designed on the flexible structure, which forms a typical elliptical cut flexible hinge profile. This profile is used as the initial flexible hinge structure of this design method. Furthermore, the structural dimension parameters of this structure are parametrically processed in the CAD model design so that they can be used as variables in subsequent design.

[0042] In a preferred embodiment, the CAD software may be UG, pore, etc.

[0043] In this embodiment, the structural parameters mainly include the vertical and horizontal directions, specifically:

[0044] like Figure 2 As shown, the vertical cut dimensions and position parameters of the initial flexible hinge structure include: major axis a1, minor axis b1, plane cut height c1, cut position L1, thickness h1, and internal tilt angle k of the flexible hinge.

[0045] like Figure 3 As shown, the dimensions and position parameters of the horizontal cut in the initial flexible hinge structure include: major axis a2, minor axis b2, plane cut height c2, cut position L2, and thickness h2;

[0046] The flexible hinge has a symmetrical structure, and the cut dimensions and position parameters on both sides adopt uniform parameters.

[0047] In a preferred embodiment, the finite element processing software in step 2 can be selected as Hypermesh, ANSA, etc.

[0048] In this embodiment, in order to obtain better optimization results, various working conditions that are of great concern to the shape of the main mirror are designed in step 3, including gravity deformation working conditions with tilt angles of 0°, 15° and 30°, as well as thermal deformation working conditions at high temperature of 60°C and low temperature of 30°C.

[0049] In a preferred embodiment, the finite element solution software can be Nastran, Abaqus, etc.

[0050] In a preferred embodiment, in step 4, the numerical fitting software is implemented using MATLAB and SigmaFit.

[0051] In this embodiment, in step 5, to obtain accurate samples, the size change step size is 0.5 mm and the angle change step size is 5° during iteration. The multi-objective optimization software can be implemented using Heeds, Hyperstudy, or Isight.

[0052] In this embodiment, step 6 includes structural dimension constraints and flexible hinge stress constraints; wherein the structural dimension constraints include: b1+c1

[0053] Furthermore, additional range constraints are proposed for the structural parameters of the flexible hinge:

[0054] In the vertical direction: the value range of the major axis a1 is 2-10mm, the value range of the minor axis b1 is 1-7mm, the value range of the plane cut height c1 is 0-7mm, the value range of the cut position L1 is 2-40mm, the value range of the numerical thickness h1 is 15-25mm, and the value range of the internal tilt angle k of the flexible hinge is 150-180°.

[0055] In the horizontal direction: the major axis a2 ranges from 2 to 12 mm, the minor axis b2 ranges from 1 to 8 mm, the plane cut height c2 ranges from 0 to 8 mm, the cut position L2 ranges from 2 to 40 mm, and the numerical thickness h2 ranges from 15 to 25 mm.

[0056] Furthermore, in this embodiment, the rigid body displacement and surface shape RMS of the primary mirror are weighted according to their magnitude of influence on imaging and used as an evaluation function to evaluate all response output target values. This approach has a more direct advantage in aligning with optical mechanics than traditional optimization methods that focus on deformation and stress.

[0057] The optimal structural parameter target value finally obtained by using the design method proposed in this embodiment is:

[0058] L1=26mm, a1=7.5mm, b1=5mm, c1=3.5mm, h1=22.5mm, k=170°;

[0059] L2=18mm, a2=6mm, b2=3.5mm, c2=3mm, h2=16mm.

[0060] ​It should be noted that, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances. The accompanying drawings in the embodiments are used to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0061] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A design method for a flexible hinge supporting a large-aperture optical telescope, characterized in that, Including: Step 1: Take the profile of a typical elliptical cut flexible hinge as the initial flexible hinge structure, and parameterize the structural dimension parameters in the CAD model. Step 2: Establish a finite element model of the primary mirror and the support structure assembled with the initial flexible hinge structure, and take the structural dimension parameters of the initial flexible hinge structure as parameter variables. Step 3: Set multiple calculation conditions, and use a finite element solver to solve and calculate the finite element model to obtain the deformation, stress of the flexible hinge structure, and the node displacement data on the surface of the primary mirror. Step 4: Take the node displacement data as the input, and use numerical fitting software to fit the input data into the mirror Zernike coefficients, as well as the rigid body displacement and surface shape RMS value of the primary mirror. Step 5: Integrate Steps 1 - Step 4 into an automated workflow. Use a multi-objective optimization algorithm to take the combination of the structural parameter variables of the flexible hinge as the input sample, and set the upper and lower limits of each variable and the step size of the dimensional change during iteration. Solve the response of the flexible hinge stress, the rigid body displacement of the primary mirror, and the surface shape RMS value through the integrated automated simulation calculation process as the output sample. Construct a mathematical surrogate model for the flexible hinge structure design variables, stress, primary mirror displacement, and deformation response using the obtained sample set. Step 6: Iteratively update the flexible hinge structure parameter variables based on the multi-objective optimization algorithm, and set the constraint conditions of the variables. Continuously select new variable combinations and substitute them into the mathematical surrogate model to calculate the target values until the maximum number of iterations is reached. Evaluate all the response output target values, and select the optimal structural parameter target value as the dimensional parameters of the flexible hinge structure.

2. The design method for a flexible hinge supporting a large-aperture optical telescope according to claim 1, characterized in that, In Step 1, the initial flexible hinge structure is: Design two sets of mutually orthogonal elliptical cuts symmetrically on the flexible structure.

3. The design method for a flexible hinge supporting a large-aperture optical telescope according to claim 2, characterized in that, In Step 1, the structural dimension parameters include: The cut size and position parameters in the vertical direction of the initial flexible hinge structure include: major axis a1, minor axis b1, plane cut height c1, cut position L1, thickness h1, and internal inclination angle k of the flexible hinge. The cut size and position parameters in the horizontal direction of the initial flexible hinge structure include: major axis a2, minor axis b2, plane cut height c2, cut position L2, thickness h2. The flexible hinge is a symmetric structure, and the cut size and position parameters on both sides adopt unified parameters.

4. The design method for a flexible hinge supporting a large-aperture optical telescope according to claim 1, characterized in that, In Step 3, the conditions include the conditions that are more concerned about the surface shape of the primary mirror, including the gravity deformation condition and the thermal deformation condition.

5. The design method for a flexible hinge supporting a large-aperture optical telescope according to claim 1, characterized in that, In Step 5, the step size of the dimensional change during iteration is 0.5 mm, and the step size of the angular change is 5°.

6. The design method for a flexible hinge supporting a large-aperture optical telescope according to claim 3, characterized in that, In Step 6, the constraint conditions include structural dimension constraints and flexible hinge stress constraints. Among them, the structural dimension constraints include: b1 + c1 < h1, a1 / 2 < L1; b2 + c2 < h2, a2 / 2 < L2; the stress value of the flexible hinge is less than 20 Mpa.

7. The design method for a flexible hinge supporting a large-aperture optical telescope according to claim 1, characterized in that, In Step 6, the evaluation method is: Weight the rigid body displacement of the primary mirror and the surface shape RMS according to the magnitude of the influence on imaging and use it as the evaluation function to evaluate all the response output target values.

8. The design method for a flexible hinge supporting a large-aperture optical telescope according to claim 4, characterized in that, The gravity deformation conditions include the gravity deformation conditions with inclination angles of 0°, 15°, and 30°.

9. The design method for a flexible hinge supporting a large-aperture optical telescope according to claim 4, characterized in that, The heat deformation conditions include high temperature (60℃) and low temperature (30℃).

Images