Large telescope cover structure and control method thereof

Abstract

The application discloses a large telescope cover structure and a control method thereof. The cover structure comprises a cover seat mechanism, a cover driving mechanism and a primary mirror covering mechanism. The cover driving mechanism comprises a longitudinal compensation device. The horizontal linear driving force of a motor is converted into a composite overturning motion of the cover through a combination of horizontal screw rod transmission and vertical guide rail compensation, effectively solving the dead point problem of the connecting rod mechanism at a specific angle. A two-stage folding design of a rectangular cover and a trapezoidal cover is adopted. The space radius swept during the opening process and the final storage height are greatly reduced. The cover body adopts an aluminum profile skeleton skin structure, which reduces the overall weight and the moment of inertia while ensuring a very low deformation of the cover under a large span, and ensures the sealing performance when closed. Key motion components such as a side rotating shaft mechanism and a motor driving device are arranged on the edge side, facilitating installation, debugging, maintenance and repair.

Description

Technical Field

[0001] This invention relates to the field of large telescope technology, specifically to a large-aperture telescope lens cover structure and its control method. Background Technology

[0002] The primary mirror of a large optical telescope is the core of the observation system. Its surface coating is extremely delicate and easily damaged by dust, moisture, sand, and accidental physical impacts. Therefore, during non-observation periods, the primary mirror must be tightly covered with a lens cap. However, as telescope apertures continue to increase (for example, reaching 2 meters or even 4 meters and above), traditional lens cap designs face serious challenges, mainly in the following aspects:

[0003] Large space occupation and susceptibility to interference with the dome: Traditional telescope covers mostly adopt either an "integral flip-top" or a "sliding sliding type." The integral flip-top type requires a huge vertical space to open; for a compact dome, the flipped-top can easily hit the inner wall of the dome or obstruct the observation light path. Furthermore, in windy conditions, the large, upright cover can create a significant sail effect, affecting the telescope's pointing stability. The sliding sliding type requires a guide rail space longer than twice the diameter of the primary mirror, resulting in an excessively large overall telescope envelope and increasing the dome's construction cost.

[0004] The drive mechanism has a "dead point," resulting in unstable movement: To achieve space-saving folding of the mirror cover, existing technologies typically employ linkage mechanisms or direct hydraulic cylinder drives. For multi-link folding mechanisms, during the initial or fully unfolded stage of folding, they often reach a "dead point" or "singularity" in the mechanical transmission, with an extremely short lever arm. This requires the drive motor to provide a huge instantaneous starting torque, which can easily lead to motor overload or mechanism jamming. Furthermore, in ordinary linear drives (such as electric actuators), when driving a load that performs circular motion, the height and angle of the connection point are constantly changing. Without a special compensation structure, motion interference and vibration are easily generated, causing jerky opening and closing processes, and even damaging the mirror surface.

[0005] The contradiction between structural rigidity and weight: The large-diameter lens cover has a large span. If a traditional welded steel structure is used, the self-weight will be too large, which will not only increase the burden on the drive system, but also easily cause sagging deformation due to its own weight, resulting in poor central sealing when closed. If the wall thickness is reduced in order to reduce weight, sufficient rigidity cannot be guaranteed, and the primary lens cannot be effectively protected when subjected to accidental falling object impact. Summary of the Invention

[0006] The primary mirror of a large optical telescope is the core observation component, and its surface quality directly affects observation accuracy. During non-observation periods or in inclement weather, effective shielding and protection of the primary mirror are necessary. Existing large telescope covers are typically bulky and heavy, and prone to significant shifts in the center of gravity or movement stagnation during opening and closing. Furthermore, for large-aperture telescopes, traditional single-piece or split-type covers occupy a large amount of space, making them unsuitable for the compact dome-shaped space. To address these issues, this invention provides a large telescope cover structure that is compact, has smooth transmission, and high rigidity.

[0007] The technical solution of the present invention is as follows:

[0008] A large telescope lens cover structure includes a lens cover seat mechanism, a lens cover drive mechanism, and a main mirror covering mechanism.

[0009] The lens cover mount mechanism includes a lens cover mount body and corner supports. The lens cover mount body is connected to the large-aperture telescope intermediate block structure through corner supports fixed at the four corners of the bottom surface. The upper surface of the lens cover mount body is fixedly connected to the main mirror covering mechanism and the lens cover driving mechanism. The lens cover driving mechanism is located on the side of the lens cover mount body.

[0010] The lens cover driving mechanism includes a motor driving device, a lateral movement device, and a longitudinal compensation device. The motor driving device includes a drive motor, a drive worm gear connected to the drive motor, and a lead screw fixing seat that fixes the drive motor to the lens cover base mechanism. The lateral movement device includes a drive worm wheel meshing with the drive worm gear, a drive ball screw connected to the drive worm wheel, a bearing that fixes the drive ball screw to the lead screw fixing seat, a lead screw support seat at the other end of the lead screw, and a translation guide rail that is installed parallel to the lead screw and fixed to the lens cover base body. The longitudinal compensation device includes a drive frame, a longitudinal guide rail connected to the side of the drive frame, a drive rod connected to the longitudinal guide rail, a bearing and a drive shaft that are concentrically installed with the round hole at the top of the drive rod. The longitudinal compensation device is connected to the upper end of the translation guide rail slider of the lateral movement device through the bottom end of the drive frame, and the inner end of the drive frame is connected to the drive ball screw nut. The lens cover driving mechanism is connected to the main lens covering mechanism through the drive shaft of the longitudinal compensation device.

[0011] The main lens covering mechanism includes a rectangular cover, a trapezoidal cover, and a side rotation shaft mechanism; the rectangular cover includes a rectangular cover plate, an aluminum profile connected to the rectangular cover plate for bottom support, and a drive joint connected to the longitudinal compensation device; the trapezoidal cover includes a trapezoidal cover plate, an aluminum profile connected to the trapezoidal cover plate for bottom support, a folding shaft connected to the rectangular cover, and a folding bearing seat; the side rotation shaft mechanism includes a side bearing seat connected to the lens cover seat body, a shaft seat connected to the trapezoidal cover, and a flipping shaft and a needle roller bearing connecting the two.

[0012] Furthermore, the primary mirror covering mechanism covers the telescope primary mirror in the unfolded state; the rectangular cover is located on the central side of the overall structure, and the trapezoidal cover is located on the outer edge side of the overall structure; the rectangular cover and the trapezoidal cover are hinged together by a folding shaft and a folding bearing seat, and the two can rotate relative to each other around the folding shaft to achieve folding or unfolding.

[0013] Furthermore, the top of the drive rod of the lens cover drive mechanism is hinged to the side of the rectangular cover through a drive joint; when the lateral moving device drives the longitudinal compensation device to move horizontally along the translation guide rail, it pushes the rectangular cover through the drive rod, causing the trapezoidal cover hinged to it to rotate around the side rotation shaft mechanism, thereby realizing the opening and closing movement of the lens cover.

[0014] Furthermore, the drive frame in the longitudinal compensation device is a triangular support structure, and the longitudinal guide rail is vertically installed on the side of the drive frame; the drive rod is slidably connected to the longitudinal guide rail through a slider, and is used to compensate for the displacement component of the drive joint in the vertical direction during the opening, closing and flipping of the mirror cover.

[0015] Furthermore, the side rotating shaft mechanism is arranged in pairs on both sides of the trapezoidal cover. One end of the rotating shaft is fixed in the aluminum profile frame of the trapezoidal cover, and the other end is supported in the side bearing seat by a needle roller bearing. The side bearing seat is fixedly installed on the edge protrusion on the upper surface of the mirror cover body.

[0016] Furthermore, the overall lens cover structure adopts a centrally symmetrical layout, including two symmetrically arranged lens cover driving mechanisms and main lens covering mechanisms; the rectangular cover plates of the two main lens covering mechanisms are joined together at the center line of the lens cover base body in the closed state to form a closed plane.

[0017] Furthermore, both the rectangular and trapezoidal cover plates adopt a lightweight aluminum profile skeleton skin structure, and the aluminum profile has internal reinforcing ribs; the edge of the rectangular cover is provided with a sealing strip for dustproof sealing when the two sets of mirror covers are closed.

[0018] Furthermore, the main body of the lens cover mount is a chamfered rectangular frame structure with a hollow interior. The translation guide rail and the lead screw fixing seat are installed on the inner side of the long side wall of the frame structure. The corner support has a height adjustment function to adjust the levelness of the main body of the lens cover mount relative to the telescope's middle block structure.

[0019] A control method based on the above-mentioned large telescope lens cover structure includes the following steps:

[0020] Step 1: Establish a kinematic mapping model based on longitudinal compensation;

[0021] Let the center of the flip axis be the origin of the coordinate system. The flip angle of the trapezoidal cover is The initial vertical offset distance of the drive connector relative to the origin O is The system will drive the ball screw to perform horizontal linear displacement. The flip angle of the trapezoidal cover Decouple the components and establish the closed-loop vector position equations of the mechanism;

[0022] Step 2: Construct the Jacobian matrix and eliminate singularities;

[0023] Extracting the output speed of the lateral movement device Angular velocity of lens cover flip Differential kinematic relationship between them:

[0024] ;

[0025] in, Let the horizontal displacement Jacobian element of the system be defined; the vertical degree of freedom is released through the longitudinal guide rail of the longitudinal compensation device, so that the vertical displacement Jacobian element is defined. It tends to a decoupled state, thereby ensuring that within the working range Inside, Eliminate dead spots in mechanical transmission;

[0026] Step 3: Generate a variable acceleration nonlinear driving trajectory;

[0027] To ensure smooth angular acceleration of the primary lens cover mechanism during opening and closing, the trapezoidal cover is designed to follow a fifth-order polynomial smooth angular velocity curve. The control system substitutes the real-time reference angle into the kinematic mapping model of step 1 to solve for the nonlinear horizontal displacement command required by the drive motor at the given moment. and speed command ;

[0028] Step 4: Implement follow control;

[0029] Servo motor receives speed command The drive frame on the translation guide rail moves horizontally with variable acceleration, and combined with the adaptive vertical sliding of the longitudinal compensation device, it achieves constant and shock-free folding and flipping of the large-span mirror cover.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] Smooth movement, avoiding jamming: This invention innovatively designs a mirror cover drive mechanism that includes a "longitudinal compensation device." Unlike traditional direct linkage drive, this invention uses a combination of "horizontal screw drive + vertical guide rail compensation" to convert the horizontal linear drive force of the motor into a compound flipping motion of the mirror cover. This effectively solves the dead point problem of the linkage mechanism at specific angles, ensuring balanced load on the motor throughout the entire stroke, avoiding the risk of jamming, and guaranteeing smooth and seamless opening and closing of the mirror cover.

[0032] Folding and storage saves space: It adopts a two-stage folding design of "rectangular cover + trapezoidal cover". During opening, the rectangular cover and trapezoidal cover fold relative to each other and stand up. Compared with the one-piece lens cover, its sweep radius and final storage height are significantly reduced, which greatly saves the valuable space inside the telescope dome, reduces the risk of obstructing the light path, effectively solves the problem of installation adaptability of large-aperture telescopes in a compact dome, and reduces the windward area.

[0033] High structural rigidity and lightweight: The main body of the lens cover adopts an aluminum profile frame and skin structure, combined with a reasonable layout of reinforcing ribs. While reducing the overall weight and rotational inertia, it ensures extremely low deformation of the lens cover under large spans. Combined with the centrally symmetrical split layout and edge sealing strip design, it ensures the sealing performance when closed, achieving a perfect balance between structural strength, weight and sealing performance.

[0034] Modular design for easy maintenance: The mirror cover mount, drive mechanism, and cover mechanism are assembled in a modular fashion. Key moving components such as the side rotation shaft mechanism and motor drive are located on the edge side, facilitating installation, debugging, and subsequent maintenance and repair. (See attached diagram for details.)

[0035] Figure 1 This is a three-dimensional schematic diagram of the overall structure of the large telescope lens cover of the present invention (closed state).

[0036] Figure 2 This is a three-dimensional structural diagram of the mirror cover holder mechanism.

[0037] Figure 3 This is a three-dimensional structural diagram of the mirror cover drive mechanism (showing the dual-sided drive layout).

[0038] Figure 4 This is a schematic diagram of the planar structure of the rectangular cover in the main mirror covering mechanism.

[0039] Figure 5 This is a schematic diagram of the trapezoidal cover in the main mirror covering mechanism.

[0040] Figure 6 This is a partial three-dimensional structural diagram of the side-rotating shaft mechanism.

[0041] In the diagram: 1-Mirror cover holder mechanism, 11-Mirror cover holder body, 12-Corner support;

[0042] 2-Mirror cover drive mechanism, 21-Drive motor, 22-Drive worm, 23-Drive worm wheel, 24-Drive ball screw, 25-Screw fixing seat, 26-Screw support seat, 27-Longitudinal compensation device, 271-Drive frame, 272-Longitudinal guide rail, 273-Drive rod, 274-Drive joint, 275-Drive shaft, 28-Translation guide rail;

[0043] 3-Main mirror cover mechanism, 31-Rectangular cover, 311-Rectangular cover plate, 312-Aluminum profile frame, 313-Corner link, 314-Folding bearing seat, 32-Trapezoidal cover, 321-Trapezoidal cover plate, 322-Folding drawer, 33-Side rotating shaft mechanism, 331-Side bearing seat, 332-Flipping shaft, 333-Needle roller bearing, 334-Shaft seat. Detailed Implementation

[0044] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0045] like Figure 1-6 As shown, this invention provides a large telescope lens cover structure, mainly composed of a lens cover base mechanism 1, a lens cover driving mechanism 2, and a main mirror covering mechanism 3. The lens cover base mechanism 1 serves as a base and is fixed to the telescope's central block structure; the main mirror covering mechanism 3 is divided into two symmetrical groups, laid flat and covering the lens cover base mechanism 1; the lens cover driving mechanism 2 is located on both sides of the lens cover base mechanism 1 and is used to drive the folding and unfolding of the main mirror covering mechanism 3.

[0046] For mirror cover seat mechanism 1, such as Figure 2 As shown, the system includes a lens cover mount body 11 and corner supports 12. The lens cover mount body 11 adopts a chamfered rectangular frame structure with a hollow interior to reduce weight. The upper surface is machined with a mounting plane for fixing the side rotation mechanism 33. The corner supports 12 are located at the four corners of the bottom surface of the lens cover mount body 11 and are used to adjust the level and height of the entire lens cover system relative to the telescope primary mirror.

[0047] For the mirror cover drive mechanism 2, such as Figure 3As shown, it adopts a composite drive design of "horizontal screw drive + longitudinal guide rail compensation". The mechanism includes a motor drive device, a lateral movement device, and a longitudinal compensation device 27. Specifically, the drive motor 21 is connected to the drive worm 22 through a reducer. The drive worm 22 meshes with the drive worm wheel 23, and the drive worm wheel 23 drives the drive ball screw 24 to rotate. The two ends of the drive ball screw 24 are fixed to the mirror cover body 11 through the screw fixing seat 25 and the screw support seat 26, respectively. The longitudinal compensation device 27 includes a triangular drive frame 271. The bottom of the drive frame 271 is provided with a slider, which is installed on the translation guide rail 28 of the mirror cover body 11. At the same time, the drive frame 271 is connected to the drive ball screw 24. A longitudinal guide rail 272 is vertically installed on the side of the drive frame 271. The drive rod 273 is installed on the longitudinal guide rail 272 through the slider and can slide freely in the vertical direction. The top of the drive rod 273 is provided with a drive shaft 275, which is connected to the rectangular cover 31 through a drive connector 274.

[0048] For the primary lens coverage mechanism 3, such as Figure 4 , Figure 5 and Figure 6 As shown, it includes a rectangular cover 31, a trapezoidal cover 32, and a side rotation mechanism 33. The rectangular cover 31 ( Figure 4 Located on the inside, trapezoidal cover 32 ( Figure 5 Located on the outside. Both are welded from an aluminum profile frame 312, with internal reinforcing ribs and a lightweight skin covering the surface (rectangular cover plate 311, trapezoidal cover plate 321). The rectangular cover 31 and the trapezoidal cover 32 are hinged together by a folding bearing seat 314 and a folding shaft 322, allowing them to rotate relative to each other. The side rotation shaft mechanism 33 ( Figure 6 The pivot point is the root support point for the entire mirror cover to flip. The side bearing seat 331 is fixed to the edge protrusion of the mirror cover seat body 11. One end of the flipping shaft 332 is fixedly connected to the side aluminum profile of the trapezoidal cover 32, and the other end is connected to the short side of the trapezoidal cover 32 through the shaft seat 334. The shaft is internally supported in the side bearing seat 331 by a high load-bearing needle roller bearing 333.

[0049] The working principle and operation process of this invention are as follows: When the telescope needs to observe and performs the opening (folding) action: the drive motor 21 starts, and after being reduced in speed by a worm gear, it drives the drive ball screw 24 to rotate. Under the drive of the screw, the drive frame 271 moves horizontally outward (away from the center line of the lens cover) along the translation guide rail 28. The drive frame 271 pulls the rectangular cover 31 outward through the drive rod 273. Since the outer edge of the trapezoidal cover 32 is restricted to fixed-axis rotation by the side rotation shaft mechanism 33, the rectangular cover 31 is forced to flip the trapezoidal cover 32 upward around the side rotation shaft mechanism 33 under the action of horizontal pulling force. At the same time, the rectangular cover 31 and the trapezoidal cover 32 fold relative to each other around the folding bearing seat 314 and the folding shaft 322.

[0050] During this process, the height of the connection point between the drive rod 273 and the rectangular cover 31 will increase as the folding angle changes. At this time, the longitudinal compensation device 27 comes into play, and the drive rod 273 slides upward along the longitudinal guide rail 272, releasing the vertical degree of freedom, compensating for the height change, and preventing the mechanism from jamming. This smoothly transforms the horizontal linear motion of the drive frame 271 into the folding and flipping motion of the mirror cover until the mirror cover is completely upright and stored.

[0051] When the main mirror needs protection and a closing (unfolding) action is performed: the motor reverses, the drive frame 271 moves inward, pushing the rectangular cover 31 down and flattening it. The drive rod 273 slides down along the longitudinal guide rail 272 to reset under the action of gravity and thrust. Finally, the two rectangular covers 31 meet at the center line, and the trapezoidal cover 32 lies flat, forming a closed plane covering the main mirror.

[0052] The present invention also provides a smooth motion control method based on the aforementioned large telescope lens cover structure, comprising the following steps:

[0053] Step 1: Establish a kinematic mapping model based on longitudinal compensation. Let the center of the flip axis 332 be the origin of the coordinate system. The flip angle of the trapezoidal cover 32 is The initial vertical offset distance of drive connector 274 relative to the origin O is The system will drive the ball screw 24 to horizontal linear displacement. The flip angle of the trapezoidal cover 32 Decouple the components and establish the closed-loop vector position equations of the mechanism;

[0054] Step 2: Construct the Jacobian matrix and eliminate singularities. Extract the output velocity of the lateral movement device. Angular velocity of lens cover flip Differential kinematic relationship between them:

[0055]

[0056] in, Let Jacobian elements represent the horizontal displacement of the system. The vertical degree of freedom is released through the longitudinal guide rail 272 in the longitudinal compensation device 27, allowing the vertical displacement Jacobian elements to be determined. It tends to a decoupled state, thereby ensuring that within the working range Inside, Eliminate dead spots in mechanical transmission;

[0057] Step 3: Generate a variable acceleration nonlinear drive trajectory. To ensure smooth angular acceleration of the primary mirror cover mechanism 3 during the opening and closing process, the trapezoidal cover 32 is set to follow a fifth-order polynomial smooth angular velocity curve. The control system substitutes the real-time reference angle into the kinematic mapping model of step 1 to solve for the nonlinear horizontal displacement command required by the drive motor 21 at the given moment. and speed command ;

[0058] Step 4: Implement follow control. The servo motor receives speed commands. The drive frame 271 on the drive translation guide 28 moves horizontally with variable acceleration, and combined with the adaptive vertical sliding of the longitudinal compensation device 27, it achieves constant and shock-free folding and flipping of the large-span mirror cover.

[0059] The kinematic decoupling and dead-point elimination principle of the longitudinal compensation mechanism is as follows:

[0060] In existing technologies, when the mirror cover is directly driven by a connecting rod or electric cylinder, the linear extension and retraction of the electric cylinder will cause normal interference with the arc trajectory because the driving point trajectory is a fixed arc. This not only leads to severe mechanical jerking but also creates a "transmission dead point" at certain angles (such as when the mirror cover is laid flat or fully upright). This invention achieves dual decoupling of mechanics and kinematics in the physical structure through the design of the longitudinal guide rail 272.

[0061] 1. Kinematic decoupling and Jacobi analysis:

[0062] Assuming the rotation center of the side rotation mechanism 33 is the origin O, the effective radius of the drive connector 274 from the origin is L, and the mirror cover flip angle is... In traditional rigid multi-link drives, the coordinates of the drive point... Must meet .

[0063] In this invention, since the longitudinal guide rail 272 releases the vertical degree of freedom, the drive frame 271 provides the horizontal displacement. It becomes an independent input variable. Its kinematic constraint equations simplify to:

[0064]

[0065]

[0066] in and Let be the initial bias constant of the structure. Taking the derivative with respect to time, we obtain the velocity mapping relationship (Jacobi matrix) of the system:

[0067]

[0068] In this structure, the driver source only controls ,Right now .because The existence of the driving point (i.e., the driving point is slightly higher than the rotation axis in the closed state) makes it possible for... At that time, the initial lever arm is not zero, thus ensuring that the entire flipping range is maintained. Internal, drive transmission coefficient (consider After biasing, the non-zero equivalent force arm never crosses the zero point, which theoretically proves that the structure has no kinematic singularities (dead points).

[0069] 2. Dynamic load balancing characteristics:

[0070] During the folding and erection process, the equivalent gravitational moment of the mirror cover Depending on the angle The change exhibits a cosine decay characteristic: .

[0071] If a traditional inclined push rod is used, the effective output angle of the push rod will change drastically, resulting in distorted peak values ​​in the motor load current. In this invention, however, the horizontal thrust provided by the lead screw 24... Always parallel to the main body 11 of the mirror cover. According to the principle of virtual work (ignoring frictional resistance), we have:

[0072]

[0073] Substituting the Jacobian relation from before The instantaneous equivalent horizontal thrust that the motor needs to overcome can be derived as follows:

[0074]

[0075] The longitudinal compensation slider 273 slides freely on the vertical guide rail, making The directional component of the force (which contributes nothing to the work done and only increases bearing friction) is absorbed by the guide rail structure and does not affect the lead screw drive chain. This torque adaptive matching mechanism minimizes the variance of the output torque of the drive motor 21 throughout the opening and closing process, effectively protecting the worm gear reduction system.

[0076] In summary, this invention provides a large telescope lens cover structure and its control method. The lens cover structure includes a lens cover base, a rectangular cover, a trapezoidal cover, a lens cover drive, and a side rotation shaft. The lens cover base is fixed to the telescope's central block. The trapezoidal cover is connected to the rectangular cover, with the former connected to the lens cover base via a hinge. The rotational motion of the drive system motor is converted into linear motion of a slider through a transmission mechanism, driving the rotation of the rectangular and trapezoidal covers, thereby controlling the opening and closing of the lens cover. When closed, this structure effectively protects the telescope's primary mirror, preventing irreversible damage from falling foreign objects or other accidents. It also prevents dust, moisture, and other impurities from contaminating the coating on the primary mirror surface, thus improving the telescope's lifespan. Furthermore, this structure exhibits high stability and durability, making it suitable for various large telescopes, especially those operating in harsh environments.

[0077] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or conventional improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the protection scope of the claims of the present invention.

Claims

1. A large telescope lens cover structure, characterized in that, This includes the lens cover mounting mechanism, the lens cover driving mechanism, and the primary lens covering mechanism; The lens cover mount mechanism includes a lens cover mount body and corner supports. The lens cover mount body is connected to the large-aperture telescope intermediate block structure through corner supports fixed at the four corners of the bottom surface. The upper surface of the lens cover mount body is fixedly connected to the main mirror covering mechanism and the lens cover driving mechanism. The lens cover driving mechanism is located on the side of the lens cover mount body. The lens cover driving mechanism includes a motor driving device, a lateral movement device, and a longitudinal compensation device. The motor driving device includes a drive motor, a drive worm gear connected to the drive motor, and a lead screw fixing seat that fixes the drive motor to the lens cover base mechanism. The lateral movement device includes a drive worm wheel meshing with the drive worm gear, a drive ball screw connected to the drive worm wheel, a bearing that fixes the drive ball screw to the lead screw fixing seat, a lead screw support seat at the other end of the lead screw, and a translation guide rail that is installed parallel to the lead screw and fixed to the lens cover base body. The longitudinal compensation device includes a drive frame, a longitudinal guide rail connected to the side of the drive frame, a drive rod connected to the longitudinal guide rail, a bearing and a drive shaft that are concentrically installed with the round hole at the top of the drive rod. The longitudinal compensation device is connected to the upper end of the translation guide rail slider of the lateral movement device through the bottom end of the drive frame, and the inner end of the drive frame is connected to the drive ball screw nut. The lens cover driving mechanism is connected to the main lens covering mechanism through the drive shaft of the longitudinal compensation device. The main lens covering mechanism includes a rectangular cover, a trapezoidal cover, and a side rotation shaft mechanism; the rectangular cover includes a rectangular cover plate, an aluminum profile connected to the rectangular cover plate for bottom support, and a drive joint connected to the longitudinal compensation device; the trapezoidal cover includes a trapezoidal cover plate, an aluminum profile connected to the trapezoidal cover plate for bottom support, a folding shaft connected to the rectangular cover, and a folding bearing seat; the side rotation shaft mechanism includes a side bearing seat connected to the lens cover seat body, a shaft seat connected to the trapezoidal cover, and a flipping shaft and a needle roller bearing connecting the two.

2. The large telescope lens cover structure according to claim 1, characterized in that, The primary mirror covering mechanism covers the telescope primary mirror in the unfolded state; the rectangular cover is located on the center side of the overall structure, and the trapezoidal cover is located on the outer edge side of the overall structure; the rectangular cover and the trapezoidal cover are hinged together by a folding shaft and a folding bearing seat, and the two can rotate relative to each other around the folding shaft to achieve folding or unfolding.

3. The large telescope lens cover structure according to claim 1, characterized in that, The top of the drive rod of the lens cover drive mechanism is hinged to the side of the rectangular cover through a drive joint; when the lateral moving device drives the longitudinal compensation device to move horizontally along the translation guide rail, the drive rod pushes the rectangular cover, causing the trapezoidal cover hinged to it to rotate around the side rotation axis mechanism, thereby realizing the opening and closing movement of the lens cover.

4. The large telescope lens cover structure according to claim 1, characterized in that, The drive frame in the longitudinal compensation device is a triangular support structure, and the longitudinal guide rail is vertically installed on the side of the drive frame; the drive rod is slidably connected to the longitudinal guide rail through a slider, and is used to compensate for the displacement component of the drive joint in the vertical direction during the opening, closing and flipping of the mirror cover.

5. The large telescope lens cover structure according to claim 1, characterized in that, The side rotating shaft mechanism is arranged in pairs on both sides of the trapezoidal cover. One end of the rotating shaft is fixed in the aluminum profile frame of the trapezoidal cover, and the other end is supported in the side bearing seat by a needle roller bearing. The side bearing seat is fixedly installed on the edge protrusion on the upper surface of the mirror cover body.

6. The large telescope lens cover structure according to claim 1, characterized in that, The overall lens cover structure adopts a centrally symmetrical layout, including two sets of symmetrically arranged lens cover driving mechanisms and main lens covering mechanisms; the rectangular cover plates of the two sets of main lens covering mechanisms are joined together at the center line of the lens cover base body in the closed state to form a closed plane.

7. The large telescope lens cover structure according to claim 1, characterized in that, Both the rectangular and trapezoidal cover plates adopt a lightweight aluminum profile skeleton skin structure, and the aluminum profile has internal reinforcing ribs; the edge of the rectangular cover is provided with a sealing strip for dust prevention and sealing when the two sets of mirror covers are closed.

8. The large telescope lens cover structure according to claim 1, characterized in that, The main body of the lens cover mount is a chamfered rectangular frame structure with a hollow interior. The translation guide rail and lead screw fixing seat are installed on the inner side of the long side wall of the frame structure. The corner support has a height adjustment function to adjust the level of the main body of the lens cover mount relative to the telescope middle block structure.

9. A control method based on the large telescope lens cover structure according to any one of claims 1 to 8, characterized in that, Includes the following steps: Step 1: Establish a kinematic mapping model based on longitudinal compensation; Let the center of the flip axis be the origin of the coordinate system. The flip angle of the trapezoidal cover is The initial vertical offset distance of the drive connector relative to the origin O is The system will drive the ball screw to perform horizontal linear displacement. The flip angle of the trapezoidal cover Decouple the components and establish the closed-loop vector position equations of the mechanism; Step 2: Construct the Jacobian matrix and eliminate singularities; Extracting the output speed of the lateral movement device Angular velocity of lens cover flip Differential kinematic relationship between them: ； in, Let the horizontal displacement Jacobian element of the system be defined; the vertical degree of freedom is released through the longitudinal guide rail of the longitudinal compensation device, so that the vertical displacement Jacobian element is defined. It tends to a decoupled state, thereby ensuring that within the working range Inside, Eliminate dead spots in mechanical transmission; Step 3: Generate a variable acceleration nonlinear driving trajectory; To ensure smooth angular acceleration of the primary lens cover mechanism during opening and closing, the trapezoidal cover is designed to follow a fifth-order polynomial smooth angular velocity curve. The control system substitutes the real-time reference angle into the kinematic mapping model of step 1 to solve for the nonlinear horizontal displacement command required by the drive motor at the given moment. and speed command ; Step 4: Implement follow control; Servo motor receives speed command The drive frame on the translation guide rail moves horizontally with variable acceleration, and combined with the adaptive vertical sliding of the longitudinal compensation device, it achieves constant and shock-free folding and flipping of the large-span mirror cover.

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