Rotary scanning imaging super-static-stability satellite platform based on superconducting magnetic suspension bearing

Abstract

The invention discloses a superconductive magnetic suspension bearing-based rotary scanning imaging super-static-stability satellite platform, which realizes suspension isolation of a rotary load and a satellite body by using the self-stability of a superconductive magnetic suspension bearing, and realizes 360-degree rotary scanning large-width imaging without active control of an optical load. A two-stage vibration isolation system for maintaining the ultra-static state of the rotating load is provided, the first-stage vibration isolation system is formed by connecting an upper spring damper and a lower spring damper in parallel, high-frequency vibration interference is isolated through passive vibration isolation, and the second-stage vibration isolation system is a superconducting magnetic suspension composite bearing. The hysteresis damping of the superconducting bearing and the eddy current damping of the permanent magnet bearing are used for isolating low-frequency noise disturbance; an I-shaped double-cabin rotating load configuration is provided, so that the rotating load cabin and the attitude control cabin are separated, and disturbance to an optical load is reduced; the attitude control cabin is overlapped with the satellite body, the centroid distance is shortened, and inertia force disturbance is reduced.

Description

Technical Field

[0001] This invention relates to the field of rotating satellite platforms and space ultrastatic stability technology, specifically to a rotary scanning imaging ultrastatic stable satellite platform based on a superconducting magnetic levitation bearing. Background Technology

[0002] As Earth observation satellites become increasingly important in global land surveillance, hydrological observation, and meteorological forecasting, the requirements for satellite imaging capabilities are becoming more stringent, especially in terms of imaging coverage and data acquisition volume. The traditional pushbroom imaging mode used by satellites is constrained by the mutual limitations of imaging width and resolution, making it difficult to improve the width imaging capability of this mode. However, using a rotary scan imaging mode on the optical payload to increase the lens scanning range by rotating or oscillating, thereby achieving ultra-wide-swath imaging, is one of the most feasible solutions to improve the imaging coverage capability of Earth observation satellites.

[0003] The key to ultra-wide swath rotary scanning imaging lies in achieving stable rotation of the optical payload. Currently, the patent document "A method for rapid rotation ultra-wide swath rotary scanning imaging of a satellite" (publication number: CN 107152926 A) suggests that satellite attitude maneuvering control is the most direct method to achieve optical payload deflection. Satellite rotation can maximize the imaging coverage of the optical payload on Earth. However, frequent attitude adjustments will exacerbate satellite propellant consumption and shorten satellite lifespan. The imaging stability of the optical payload depends on the attitude control capability of the satellite itself.

[0004] The patent document "A wide-angle imaging system with a wobbling mirror" (publication number: CN 105043353 A) can achieve multi-angle shooting by wobbling the mirror with an optical load, which reduces the energy consumption of spacecraft. However, it has limited improvement on the width of the shooting field of view, and the sensitivity requirements of the mirror wobbling component are extremely high. Frequent wobbling of the mirror can easily cause wear.

[0005] The patent document "A method for controlling the attitude of a rotating load satellite with load as the center and platform following" (publication number: CN110147115A) isolates the optical load from the satellite body through an electromagnetic levitation bearing. The optical load achieves 360° spin while the satellite body maintains its attitude. However, the electromagnetic bearing requires a very complex control system to maintain the stability of the load, which greatly increases the weight load on the satellite. Moreover, the magnetic gap of the bearing is easily affected by satellite disturbances.

[0006] The aforementioned optical payload rotation method has limitations such as limited scanning range, high difficulty in stability control, and payload stability being constrained by the satellite's attitude control accuracy.

[0007] Therefore, this invention proposes a rotary scanning imaging ultrastatic stable satellite platform based on a superconducting magnetic levitation bearing. The superconducting magnetic levitation composite bearing is used to realize a payload platform that is suspended and isolated from the main satellite, which can realize 360° low-friction rotation ultra-wide imaging of the optical payload. The self-stability of the superconducting magnetic levitation system greatly reduces the complexity of suspension control. The magnetic hysteresis damping and eddy current damping of the bearing are used to achieve passive vibration isolation, reducing the vibration transmission between the satellite and the optical payload. Summary of the Invention

[0008] The purpose of this invention is to address the problems of limited scanning range, high difficulty in stability control, and the limitation of payload stability by the satellite's attitude control precision in existing Earth observation satellite scanning imaging methods, making it difficult to achieve ultra-static, low-disturbance, and wide-range imaging. This invention provides an ultra-statically stable satellite platform for rotary scanning imaging based on a superconducting magnetic levitation bearing. Utilizing the self-stabilizing levitation of the superconducting magnetic levitation bearing, it achieves 360° rotation of the optical payload without control, significantly reducing the satellite's structural mass and control complexity; and leveraging the extremely low friction loss coefficient of the bearing (<10). -6 It greatly reduces the energy consumption required to maintain the rotation of the load; low-frequency passive vibration isolation is achieved through the combination of hysteresis damping and eddy current damping of superconducting bearings and permanent magnet bearings, maintaining the ultrastatic stability of the optical load; the rotating load adopts an "I"-shaped dual-module configuration consisting of a rotating load module and an attitude control module, which reduces the distance between the center of mass of the rotating load and the satellite body and reduces inertial force disturbance.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A rotary scanning imaging ultrastatic stable satellite platform based on a superconducting magnetic levitation bearing consists of two parts: a rotating payload and a satellite body. The rotating payload, as a rotating component, is responsible for driving the optical payload to rotate, achieving a 360° scanning range. The satellite body, as the basic platform carrying the rotating payload, is responsible for propulsion along the satellite orbit and providing the cryogenic environment for the superconducting magnetic levitation bearing. The rotating payload specifically includes: a rotating payload cabin, an optical payload, a permanent magnet on the moving frame, a central shaft of the moving frame, an attitude control cabin, an attitude control flywheel, and a combined magnet on the moving frame. The satellite body specifically includes: an upper vibration isolation platform, a lower permanent magnet on the fixed frame, an upper spring damper, a satellite superconducting bearing cavity, the satellite body, solar panels, a superconducting magnet, a copper chain cooling sample holder, a lower spring vibration isolator, and a miniature refrigerator.

[0011] The rotating load and the satellite body are connected by a superconducting magnetic levitation composite bearing. The superconducting magnetic levitation composite bearing is the core of the entire system and is used to achieve self-stabilized levitation and 360° low-friction rotation. The superconducting magnetic levitation composite bearing consists of two parts: a permanent magnet bearing and a superconducting bearing. The permanent magnet bearing consists of a permanent magnet on the moving frame and a permanent magnet on the fixed frame. The superconducting bearing consists of a combined magnet on the moving frame and a superconducting magnet. The levitation forces of the two bearings are balanced to maintain the rotation of the rotating load.

[0012] The rotating payload consists of two parts: the rotating payload cabin and the attitude control cabin. The two cabins are connected by a central axis of the moving frame. The rotating payload cabin, the central axis of the moving frame, and the attitude control cabin together form an "I"-shaped structure. The separate configuration of the two cabins ensures that the attitude control flywheel will not cause electromagnetic disturbances to the optical payload in the rotating payload cabin. The attitude control cabin has a fixed standard configuration, while the rotating payload cabin can be adjusted and replaced according to the structure of the optical payload, saving research and development costs.

[0013] The rotating load is initially secured by a locking and releasing mechanism with a shape memory alloy plug. The preload of the shape memory alloy plug ensures that the rotating load will not fall off during launch. When operating in space, the rotating load is released by electrically heating and shrinking the shape memory alloy plug.

[0014] The rotating load chamber is the chamber in which the working load of this system is installed. It is a cylindrical chamber structure with external windows for the optical load on the side of the chamber.

[0015] The optical payload is installed inside the rotating payload chamber, and the optical payload achieves 360° scanning as the chamber rotates.

[0016] The permanent magnet on the moving frame is located below the rotating load chamber, serving as the upper part of the permanent magnet bearing.

[0017] The attitude control cabin houses an attitude control flywheel system that controls the rotational speed of the entire payload. The rotational axis of the rotating payload, the rotational axis of the attitude control flywheel, and the central axis of the moving frame are aligned to reduce rotational eccentricity torque. The combined magnet of the attitude control cabin and the moving frame is submerged within the satellite's superconducting bearing cavity, ensuring that the volume of the attitude control cabin coincides with that of the satellite's main body. This reduces the distance between the center of mass of the rotating payload and the center of mass of the satellite's main body, minimizing the impact of inertial forces.

[0018] The moving frame combined magnet is located below the attitude control cabin, serving as the magnet part of the superconducting bearing. The moving frame combined magnet adopts a concentric ring splicing configuration, divided into 6 layers radially. From the inside out, it consists of an aluminum outer magnet shell, a soft iron outer magnetic shielding ring, a neodymium iron boron outer magnet ring, a neodymium iron boron middle magnet ring, a neodymium iron boron inner magnet ring, and a soft iron inner magnetic shielding ring. The outer, middle, and inner magnet rings follow a Halbach magnet configuration radially, with the outer magnet ring radially inward, the middle magnet ring axially downward, and the inner magnet ring radially outward. The outer and inner magnet rings are N-lobed fan-shaped magnet splicing configurations. To ensure the uniformity of the axial magnetic field, N≥12. To prevent the magnetic field of the combined magnet from affecting the components inside the attitude control cabin, a magnetic shielding plate is added above the moving frame combined magnet.

[0019] The satellite body consists of, from top to bottom, an upper vibration isolation platform for mounting the permanent magnet, a superconducting magnet, a refrigerator, and the main body of the satellite.

[0020] The upper vibration isolation platform is located at the top of the satellite body and is used to isolate the vibration between the satellite body and the permanent magnet bearing. The vibration isolation platform is connected to the satellite body through 6 upper spring dampers.

[0021] The six upper spring dampers are arranged in pairs, with the two spring dampers in each pair arranged in a triangle. The three pairs of spring dampers are evenly distributed around the circumference. The vibration isolation platform is larger at the bottom and smaller at the top. The spring dampers are placed at an angle to maintain the stability of the vibration isolation platform.

[0022] The permanent magnet under the fixed frame is installed inside the upper vibration isolation platform of the satellite, serving as the lower half of the permanent magnet bearing.

[0023] The superconducting magnet is located inside the satellite body, serving as the lower part of the superconducting bearing. It uses a large-size yttrium barium copper oxide cylindrical superconductor and is isolated from the external space environment to avoid the influence of space thermal radiation.

[0024] The refrigerator is located below the superconductor and is used to cool the superconducting magnet. It adopts a miniature Stirling refrigerator and keeps the temperature of the superconducting magnet below 80K through conduction cooling. The miniature Stirling refrigerator realizes the miniaturization and integration of the superconducting magnet cooling system in space.

[0025] A copper chain cooling sample holder is used to connect the micro-crystal and the superconducting magnet. Considering the vibration and noise of the cryo-magnet during operation, the soft connection reduces the transmission of vibration and noise from the cryo-magnet to the superconductor. The heat between the two is conducted through a copper braided cooling chain. An aluminum nitride superconductor cover plate is added above the superconductor. The aluminum nitride material reduces the eddy current loss during the rotation of the superconducting bearing.

[0026] The superconductor sample holder is supported by four lower spring vibration isolators. The upper part of the lower spring vibration isolators is connected to the sample holder through thermal insulation support, and the lower part is connected to the satellite body. This reduces the impact of satellite body vibration on the superconducting bearing, prevents heat from the lower spring vibration isolators from being transferred to the superconductor, and avoids affecting the superconductor's cooling temperature.

[0027] A rotary scanning imaging ultrastatic stable satellite platform based on a superconducting magnetic levitation bearing uses a two-stage vibration isolation system to achieve vibration isolation of rotating loads and ultrastatic stable operation. The first stage of the two-stage vibration isolation system consists of an upper spring damper and a lower spring damper connected in parallel, which isolates high-frequency vibration interference through passive vibration isolation. The second stage vibration isolation system is a superconducting magnetic levitation composite bearing, which uses the hysteresis damping of the superconducting bearing and the eddy current damping of the permanent magnet bearing to isolate low-frequency noise disturbances.

[0028] The advantages of this invention are as follows:

[0029] (1) A rotary scanning imaging ultrastatic stable satellite platform based on superconducting magnetic levitation bearing. Its advantages are that the superconducting magnetic levitation composite bearing has low friction loss and low difficulty in self-stabilizing suspension control. The superconducting bearing provides adsorption force and the permanent magnet bearing provides repulsion force to maintain the large air gap of the superconducting magnetic levitation bearing, reduce bearing rotation loss, and the extremely low friction loss coefficient of the superconducting composite bearing reduces the energy required to maintain the load rotation.

[0030] (2) A rotary scanning imaging ultrastatic stable satellite platform based on superconducting magnetic levitation bearing. Its advantage is that a two-stage vibration isolation system composed of spring damper and superconducting magnetic levitation composite bearing is constructed. The first-stage vibration isolation system is composed of two sets of spring vibration isolation systems connected in parallel to achieve high-frequency vibration isolation. The second-stage vibration isolation system is composed of superconducting magnetic levitation composite shaft using hysteresis damping and eddy current damping to achieve low-frequency vibration isolation. The two-stage vibration isolation systems are connected in series to achieve full-band vibration isolation between optical payload and satellite body.

[0031] (3) A rotating scanning imaging ultrastatic stable satellite platform based on superconducting magnetic levitation bearing has the advantage that the rotating payload adopts an "I"-shaped configuration that isolates the attitude control cabin and the optical payload cabin, which can avoid the attitude control flywheel in the attitude control cabin from disturbing the optical payload; in addition, the attitude control cabin is a fixed standardized unit, while the rotating payload cabin is adjusted and replaced according to the structure of the optical payload, which can save research and development costs.

[0032] (4) A rotating scanning imaging ultrastatic stable satellite platform based on superconducting magnetic levitation bearing, the advantage of which is that the attitude control cabin in the rotating load is sunk into the satellite superconducting bearing cavity, and the two volumes overlap, reducing the distance between the center of mass of the rotating load and the attitude control cabin, and reducing the inertial force.

[0033] (5) A rotary scanning imaging ultrastatic stable satellite platform based on superconducting magnetic levitation bearing, the advantages of which are that the superconducting magnet and the micro-refrigeration unit are connected by a copper chain cooling sample frame, in which the superconducting sample frame and the cold finger connector are separated, and a copper braided cold chain is used in the middle for heat conduction, which can avoid the vibration of the refrigerator working to be transmitted to the superconducting magnet, and can also avoid damage to the cold head of the refrigerator during launch; the superconducting magnet is connected to the satellite body using a spring vibration isolator with thermal insulation support column.

[0034] (6) A rotary scanning imaging ultrastatic stable satellite platform based on superconducting magnetic levitation bearing, the advantages of which are that the moving frame combined magnet adopts a Halbach ring magnet configuration with magnetic shielding, and the radial direction consists of an outer magnet shell, an outer magnetic shielding ring, an outer magnet ring, a middle magnet ring, an inner magnet ring, and an inner magnetic shielding ring. The magnetic poles of the three middle magnet rings are arranged in the Halbach permanent magnet array to ensure strong magnetic focusing of the combined magnet. The outer magnet ring and the inner magnet ring are spliced ​​together with N fan-shaped magnets, and N≥12 ensures the uniformity of the circumferential magnetic field of the moving frame combined magnet. The outer magnetic shielding ring, the inner magnetic shielding ring, and the upper magnetic shielding plate ensure low leakage magnetism of the combined magnet on the non-working surface.

[0035] (7) A superstatically stable satellite platform for rotary scanning imaging based on superconducting magnetic levitation bearings, the advantage of which is that the optical payload adopts a rotating scanning working mode relative to the satellite body, and the entire payload controls the rotation of a single degree of freedom to achieve scanning of the superconducting swath of the Earth, reducing control complexity and increasing scanning range.

[0036] The beneficial effects of this invention are as follows: Addressing the problems of limited scanning range, high difficulty in stable suspension control, and significant satellite-body disturbance to optical payloads in existing Earth observation satellite rotating scanning modes, this invention proposes a superstatically stable rotating scanning imaging satellite platform based on superconducting magnetic levitation bearings. It utilizes the self-stabilizing suspension and extremely low friction loss of superconducting magnetic levitation bearings to achieve near-zero resistance 360° rotation of the optical payload, reducing control complexity and energy consumption for maintaining payload rotation. A two-stage vibration isolation system is constructed by combining a superconducting magnetic levitation composite bearing with low-frequency vibration isolation capability and a high-frequency vibration-isolated spring-damped system, achieving superstatically stable suspension of the optical payload. An "I"-shaped rotating payload configuration is proposed, separating the attitude control cabin and the rotating payload cabin, reducing electromagnetic disturbances to the optical payload from the flywheel system in the attitude control cabin. The configuration, with the attitude control cabin submerged within the satellite body and the rotating payload cabin outside, shortens the distance between the satellite and the payload's center of mass, reducing inertial force disturbances. The proposed configuration of a miniature refrigerator cooling the superconducting magnet establishes a miniaturized cryogenic cooling system for superconductors below 80K in the space environment. This invention overcomes the shortcomings of traditional satellite attitude control scanning and electromagnetic bearing rotation scanning methods, effectively reduces the complexity of the control system for satellite rotation scanning mode, reduces vibration disturbances, and improves suspension stability. Attached Figure Description

[0037] Figure 1 This is a front view schematic diagram of a rotary scanning imaging ultrastatic stable satellite platform based on a superconducting magnetic levitation bearing according to the present invention.

[0038] Figure 2 This is a schematic diagram of the rotating load of the present invention.

[0039] Figure 3 This is a schematic diagram of the satellite body of the present invention.

[0040] Figure 4 This is a schematic diagram of the copper chain cooling sample holder of the present invention.

[0041] Figure 5 This is a schematic diagram of the locking and releasing mechanism of the present invention.

[0042] Figure 6 This is a schematic diagram of the satellite platform rotation scanning process of the present invention.

[0043] In the diagram: 1. Rotating payload chamber; 2. Permanent magnet on the moving frame; 3. Central shaft of the moving frame; 4. Attitude control chamber; 5. Attitude control flywheel; 6. Combined magnet on the moving frame; 7. Upper vibration isolation platform; 8. Lower permanent magnet on the fixed frame; 9. Upper spring damper; 10. Satellite superconducting bearing cavity; 11. Satellite body; 12. Solar panel; 13. Superconducting magnet; 14. Copper chain cooling sample rack; 15. Lower spring vibration isolator; 16. Miniature refrigerator; 17. Locking and release mechanism; 18. Optical payload; 19. 20. Upper permanent magnet fixing shell; 21. Lower permanent magnet fixing shell; 22. Superconductor cover plate; 23. Thermal insulation support column; 6-1. Magnet outer shell; 6-2. Outer magnetic shielding ring; 6-3. Outer magnetic ring; 6-4. Middle magnetic ring; 6-5. Inner magnetic ring; 6-6. Inner magnetic shielding ring; 6-7. Upper magnetic shielding plate; 14-1. Superconductor sample holder; 14-2. Copper braided cold chain; 14-3. Cold finger connector; 17-1. Fixing ring; 17-2. Shape memory alloy bolt; 17-3. Compression ring. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and implementation guidelines.

[0045] This invention discloses a rotary scanning imaging ultra-static stable satellite platform based on a superconducting magnetic levitation bearing. It utilizes the self-stabilizing suspension characteristics and low rotational friction characteristics of the superconducting magnetic levitation composite bearing to achieve 360° uncontrolled, low-loss rotation of the optical payload above the satellite platform. It adopts a rotating scanning mode to achieve ultra-wide swath imaging of the Earth observation satellite. Through a two-stage vibration isolation system, it effectively reduces the vibration transmission between the optical payload and the satellite body, ensuring the ultra-static stable working state of the optical payload.

[0046] The system structure is as follows Figure 1 As shown, 1. Rotating load chamber; 2. Permanent magnet on the moving frame; 3. Central shaft of the moving frame; 4. Attitude control chamber; 5. Attitude control flywheel; 6. Combined magnet of the moving frame; 7. Upper vibration isolation platform; 8. Lower permanent magnet of the fixed frame; 9. Upper spring damper; 10. Satellite superconducting bearing cavity; 11. Satellite body; 12. Solar panel; 13. Superconducting magnet; 14. Copper chain cooling sample rack; 15. Lower spring vibration isolator; 16. Miniature refrigerator; 17. Locking and release mechanism.

[0047] The aforementioned ultrastatic stable satellite platform for rotary scanning imaging based on superconducting magnetic levitation bearings includes two parts: a rotating load and a satellite body. The rotating load serves as a moving frame, while the satellite body serves as a stationary frame. After entering the working state, the rotating load rotates relative to the satellite body along a fixed axis, thereby achieving rotating scanning of the Earth.

[0048] The rotating load is connected to the satellite body in a non-contact manner through a superconducting magnetic levitation composite bearing. The upper part of the superconducting magnetic levitation composite bearing is a permanent magnet bearing composed of a moving frame upper permanent magnet (2) and a fixed frame lower permanent magnet (8). The permanent magnet bearing is supported directly below the rotating load cabin (1). The lower part of the superconducting magnetic levitation composite bearing is a superconducting bearing composed of a moving frame combined magnet (6) and a superconducting magnet (13). The superconducting bearing is supported below the attitude control cabin (4). The levitation forces of the superconducting bearing and the permanent magnet bearing are balanced, and together they maintain the levitation state of the rotating load. At the same time, the superconducting magnetic levitation composite bearing can levitation and vibration isolation, and is the second-level vibration isolation system of the entire system.

[0049] In a superconducting magnetic levitation composite bearing, the permanent magnet bearing provides an upward repulsive force F against the rotating load. PM Superconducting bearings provide a downward attractive force F against rotating loads. HTS The upward repulsive force of the permanent magnet bearing can increase the levitation air gap of the superconducting bearing, thereby reducing bearing friction loss. For the superconducting magnetic levitation composite bearing to maintain a stable levitation state, the air gap between the two bearings must meet the following two conditions:

[0050] Condition 1: Suspension forces are in equilibrium, and the repulsive force F of the permanent magnet bearing is... PM Equal to the attraction force F of the superconducting bearing HTS :

[0051] F PM =F HTS

[0052] Condition 2: Since permanent magnet bearings are unstable while superconducting bearings are self-stabilizing, the stability of a superconducting magnetic levitation composite bearing requires that the stiffness of the permanent magnet bearing be less than that of the superconducting bearing.

[0053]

[0054] L1 represents the air gap between the permanent magnet (2) on the moving frame and the permanent magnet (8) on the moving frame in the permanent magnet bearing suspension, and L2 represents the air gap between the combined magnet (6) and the superconducting magnet (13) on the moving frame in the superconducting bearing. The rotating load chamber (1) and the attitude control chamber (4) are rigidly connected by the moving frame central shaft (3), and dL1 = dL2.

[0055] Figure 2The diagram shows the rotating load: 1. Rotating load chamber; 2. Permanent magnet on the moving frame; 3. Central shaft of the moving frame; 4. Attitude control chamber; 5. Attitude control flywheel; 6. Combined magnet of the moving frame; 12. Solar panel; 18. Optical load; 19. Fixed shell of the upper permanent magnet; 6-1. Outer shell of the magnet; 6-2. Outer magnetic shielding ring; 6-3. Outer magnet ring; 6-4. Middle magnet ring; 6-5. Inner magnet ring; 6-6. Inner magnetic shielding ring; 6-7. Upper magnetic shielding plate.

[0056] The rotating load has a circumferentially distributed structure with an overall "I" shape. The upper chamber is the rotating load chamber (1), the middle chamber is the moving frame central axis (3), and the lower chamber is the attitude control chamber (4). The volume and mass layout of the entire rotating load is approximately rotationally symmetrical, which reduces the deflection torque during rotation. The rotating load chamber (1) is equipped with an optical load (18) for ground imaging, and the lens of the optical load (18) is aligned with the external window of the rotating load chamber (1). The attitude control chamber (4) is equipped with an attitude control flywheel (5), and the rotation axis of the attitude control flywheel (5) is completely coincident with the moving frame central axis (3). Only a single-degree-of-freedom attitude control flywheel is needed to achieve attitude control of the optical load (18).

[0057] Solar panels (12) are added to the left and right sides of the rotating payload cabin (1). The solar panels (12) provide power to the optical payload (18) and the attitude control flywheel (5).

[0058] The permanent magnet (2) on the ring moving frame is fixed below the rotating load chamber (1) by the upper permanent magnet fixing shell (19). The permanent magnet (2) on the moving frame uses neodymium iron boron magnets, and the permanent magnet fixing shell (19) uses iron material with magnetic conductivity to shield the magnetic field emitted outward by the magnet.

[0059] The attitude control cabin (4) is connected to the moving frame assembly magnet (6) via a central shaft. Considering that the magnetic field strength of the moving frame assembly magnet will affect the levitation force F of the superconducting magnetic levitation bearing, HTS and levitation stiffness dF HTSThe size of / dL2 is limited, and the magnetic field strength of a single magnet is limited. The moving frame combined magnet (6) uses a multi-layer ring magnet combination configuration. From the outside to the inside, it consists of the outer shell of the magnet (6-1), the outer magnetic shielding ring (6-2), the outer magnet ring (6-3), the middle magnet ring (6-4), the inner magnet ring (6-5), and the inner magnetic shielding ring (6-6). An upper magnetic shielding plate (6-7) is added on top. The magnetic poles of the outer magnet ring (6-3) are radially inward, the magnetic poles of the middle magnet ring (6-4) are axially downward, and the inner magnet ring (6-5) is radially outward. The magnetic field is strongly concentrated at the middle magnet ring (6-4). The magnetic field at 0.5mm on the surface of the middle magnet ring (6-4) is >1T. The outer shell of the magnet (6-1), the inner magnetic shielding ring (6-6), and the upper magnetic shielding plate (6-7) form a magnetic shielding cylinder with an opening at the bottom to prevent the magnetic field of the magnet from affecting the operation of the attitude control flywheel (5) inside the attitude control cabin (4).

[0060] The outer magnet ring (6-3) and the inner magnet ring (6-5) use N-lobed fan-shaped magnet splicing to achieve the magnetic poles along the radial direction. In order to avoid the non-uniformity of the circumferential magnetic field caused by splicing, N≥12, and ensure that the circumferential magnetic field fluctuation of the middle magnet ring (6-4) is less than 10mT for more than 1mm.

[0061] Figure 3 The diagram shows the satellite body of the system, 7. Upper vibration isolation platform; 8. Lower permanent magnet of the fixed frame; 9. Upper spring damper; 10. Satellite superconducting bearing cavity; 11. Satellite body; 12. Solar panel; 13. Superconducting magnet; 14. Copper chain cooling sample rack; 15. Lower spring vibration isolator; 16. Miniature refrigerator; 204. Lower permanent magnet fixing shell; 21. Superconducting cover plate; 22. Thermal insulation support column.

[0062] A vibration isolation platform (7) is installed above the satellite body (11) to achieve primary passive vibration isolation of the permanent magnet (8) under the fixed frame; the satellite superconducting bearing cavity (10) is located slightly above the satellite body (11). This cavity has a cylindrical concave structure and is used to accommodate the attitude control cabin (4) and the moving frame combined magnet (6) for rotating loads. The overlap of the volumes of the satellite body (11) and the attitude control cabin (4) reduces the distance between the center of mass of the rotating load and the satellite body, making... Figure 1 The center of mass of the rotating load is shifted downward, reducing the disturbance of inertial torque; a superconducting magnet (13) and its cooling system are installed inside the satellite body (11); solar panels (12) are installed on both sides of the satellite body (11), and the solar panels (12) provide energy for the satellite.

[0063] The upper vibration isolation platform (7) and the satellite body (11) are connected by 6 upper spring dampers (9). The structure of the three is similar to a frustum structure. The 6 upper spring dampers (9) are evenly distributed above the satellite body (11) and connected to the upper vibration isolation platform (7) and the satellite body (11) through ball bearings. The 6 upper spring dampers (9) are divided into three groups, with 2 upper spring dampers (9) forming one group. The top of each group of upper spring dampers (9) is connected to the upper vibration isolation platform (7). Each group has an approximate triangular structure. This structure can achieve 6-degree-of-freedom vibration isolation.

[0064] The cooling system of the superconducting magnet includes: a superconducting magnet (13), a copper chain cooling sample holder (14), and a micro-crystal (16). The micro-crystal (16) uses a pulse tube cryostat, and the cold finger temperature of the cryostat can reach a low temperature of 60K. The cold finger of the micro-crystal (16) is connected to the superconducting magnet (13) through the copper chain cooling sample holder (14). The temperature difference between the upper surface of the superconducting magnet (13) and the cold finger is less than 21K, ensuring that the temperature of the superconducting magnet (13) is below 80K.

[0065] The superconducting magnet (13) is pressed and fixed above by a superconducting cover plate (21). The superconducting cover plate (21) is made of aluminum nitride to reduce the eddy current loss of the superconducting bearing and has a thickness of less than 1 mm. The superconducting magnet (13) is connected to the satellite body (11) below by a lower spring vibration isolator (15). The lower spring vibration isolator (15) is also a component of the first-level vibration isolation system. In order to avoid heat leakage caused by direct connection between the superconducting magnet (13) and the lower spring vibration isolator (15), thermal insulation support column (22) is used to thermally isolate the two.

[0066] The upper spring damper (9) and the lower spring isolator (15) form the first-level vibration isolation system between the rotating load and the satellite body to suppress high-frequency vibration. The superconducting magnetic levitation composite bearing composed of the upper permanent magnet (2), the fixed frame lower permanent magnet (8), the moving frame combined magnet (6), and the superconducting magnet (13) is the second-level vibration isolation system, used to suppress low-frequency vibration. The first-level vibration isolation system and the second-level vibration isolation system form a two-level vibration isolation system, which is used to achieve ultra-static stability of the optical load (18).

[0067] Figure 4 The diagram shown is of the copper chain cooling sample rack. The copper chain cooling sample rack (14) consists of three parts from top to bottom: superconductor sample rack (14-1), copper braided cold chain (14-2), and cold finger connector (14-3).

[0068] The copper chain cooling sample holder (14) avoids hard mechanical contact between the superconducting magnet (13) and the micro-refrigeration unit (16). On the one hand, it avoids damage to the weak cold finger components of the micro-refrigeration unit (16) during operation, and on the other hand, it reduces the disturbance of the copper chain cooling sample holder (14) caused by the vibration of the micro-refrigeration unit (16) during operation. The copper braided cold chain (14-2) can ensure heat conduction between the superconducting magnet (13) and the micro-refrigeration unit (16) without direct contact.

[0069] Figure 5 The diagram shown is of the locking and releasing mechanism. The locking and releasing mechanism (17) includes an annular retaining ring (17-1), three shape memory alloy bolts (17-2), and an annular clamping ring (17-3).

[0070] Figure 6 The diagram illustrates the satellite platform rotation scanning process of this invention. Specifically, the satellite advances along its orbital direction, while the payload rotates relative to the satellite, achieving a strip-shaped scan of the Earth. The scanning direction is scan area 1 → scan area 2 → scan area 3. Figure 6 The intervals between the scanning areas are only for ease of description; in reality, there is local overlap between two consecutive scanning areas to ensure seamless imaging.

[0071] The installation sequence before starting work is as follows.

[0072] Step 1: Combine the copper chain cooling sample holder (14) and the miniature refrigerator (16) and install them inside the satellite body (11);

[0073] Step 2: Fix the four lower spring vibration isolators (15) and the thermal insulation support column (22) to the mounting plate inside the satellite body (11), and fix the top of the thermal insulation support column (22) to the four mounting holes of the superconductor sample holder (14-1);

[0074] Step 3: Place the superconducting magnet (13) inside the superconducting sample holder (14-1), and press it down with the superconducting cover plate (21) to ensure that the distance between the superconducting magnet (13) and the upper surface of the satellite superconducting bearing cavity (10) is less than 3mm;

[0075] Step 4: The moving frame assembly magnet (6), attitude control cabin (4), and moving frame central shaft (3) in the rotating load are combined and connected, and the attitude control flywheel (5) is fixed at the center of the attitude control cabin (4);

[0076] Step 5: Place the part of the rotating load assembly from Step 4 into the satellite superconducting bearing cavity (10);

[0077] Step 6: Install the locking and releasing mechanism (17). The locking and releasing mechanism's fixing ring (17-1) is fixed above the satellite body (11), and the lower clamping ring (17-3) clamps the attitude control cabin (4). The shape memory alloy bolt (17-2) applies the initial preload.

[0078] Step 7: Connect the upper vibration isolation platform (7) and the satellite body (11) using the upper spring damper (9);

[0079] Step 8: Install the optical load (18) inside the rotating load chamber (1), and fix the permanent magnet (2) on the moving frame to the bottom of the rotating load chamber (1) using the upper permanent magnet fixing housing (19).

[0080] Step 9: Connect and fix the rotating load chamber (1) assembly from Step 7 to the central shaft (3) of the moving frame to complete the assembly.

[0081] The operating procedure is as follows:

[0082] Before operation, the rotating load and the satellite body are completely fixed by a locking and releasing mechanism to prevent the rotating load from falling off during satellite launch. At this time, the gap between the superconducting magnet and the moving frame combined magnet is less than 5mm.

[0083] After the satellite successfully enters orbit, it officially enters the working state. At this time, the micro-crystal (16) is started to continuously cool until the temperature of the superconducting magnet (13) is detected to be below 80K. It is considered that the superconducting magnet has officially entered the working state. At this time, the micro-crystal (16) is controlled by feedback to ensure that the temperature of the superconducting magnet (13) remains stable with a temperature fluctuation of <0.5K.

[0084] After the temperature of the superconducting magnet (13) stabilizes for 10 minutes, the shape memory alloy plug (17-2) is heated by electricity. The shape memory alloy plug (17-2) shrinks by 2 mm, and the clamping ring (17-3) loosens its fixation on the attitude control cabin (4), and it officially enters the levitation state. At this time, the permanent magnet bearing provides an upward repulsive force to the rotating load cabin (1). When L1 and L2 increase synchronously, the superconducting bearing generates a downward attractive force to the attitude control cabin (4). When the attractive force and the repulsive force are balanced, the rotating load officially enters the levitation stabilization stage. The upward offset of the rotating load in this system is less than 1 mm.

[0085] Once the rotating load is suspended and stabilized, the attitude control flywheel (5) inside the attitude control cabin (4) is activated to make the rotating load rotate until it stabilizes at the specified speed. At this time, the optical load is officially activated and scanning imaging begins.

[0086] The optical payload scanning process is as follows Figure 6As shown, when the satellite is running along the designated satellite orbit, the optical payload rotates around the axis to scan. One scan can collect a strip of Earth image. At the same time, after the satellite moves forward a certain distance, the optical payload begins to scan a second time and collect a second strip of Earth image. This process is repeated. Multiple strip images can be stitched together to form complete map information.

[0087] The above embodiments are only used to clearly illustrate the technical features of the present invention so that those skilled in the art can easily understand and implement it, and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made without departing from the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rotary scanning imaging ultrastatic stable satellite platform based on a superconducting magnetic levitation bearing, characterized in that, It comprises two parts: a rotating payload and the satellite body, characterized in that, The rotating load consists of two parts: a rotating load cabin (1) and an attitude control cabin (4). The rotating load cabin (1) and the attitude control cabin (4) are connected by a moving frame central shaft (3). An optical load (18) is installed in the rotating load cabin (1). A permanent magnet (2) is located below the rotating load cabin (1). An attitude control flywheel (5) is installed in the attitude control cabin (4). A moving frame combined magnet (6) is installed below the attitude control cabin (4). The moving frame combined magnet (6) is placed in the satellite superconducting bearing cavity (10). The attitude control cabin (4) is initially fixed by a locking and releasing mechanism (17) with a shape memory alloy bolt (17-2). The satellite body includes a satellite body (11), solar panels (12), an upper vibration isolation platform (7), a superconducting magnet (13), and a micro-crystal (16). The upper vibration isolation platform (7) is installed above the satellite body (11) via an upper spring damper (9). A fixed lower permanent magnet (8) is installed on the upper vibration isolation platform (7). The superconducting magnet (13) and the micro-crystal (16) are installed inside the satellite body (11). The superconducting magnet (13) and the micro-crystal (16) exchange heat through a copper chain cooling sample rack (14). The superconducting magnet (13) is pressed down with a superconducting cover plate (21). The superconducting sample rack (14-1) in the copper chain cooling sample rack (14) is fixed above the lower spring vibration isolator (15) using an insulating support column (22). The permanent magnet (2) on the moving frame and the permanent magnet (8) on the fixed frame form a permanent magnet bearing, the combined magnet (6) on the moving frame and the superconducting magnet (13) form a superconducting bearing, the permanent magnet bearing and the superconducting bearing form a superconducting magnetic levitation composite bearing, and the rotating load and the satellite body are connected non-contactly through the superconducting magnetic levitation composite bearing during operation.

2. The ultra-statically stable rotary scanning imaging satellite platform based on a superconducting magnetic levitation bearing as described in claim 1, characterized in that, The upper spring damper (9) and the lower spring isolator (15) form the first-level vibration isolation system between the rotating load and the satellite body to suppress high-frequency vibration. The superconducting magnetic levitation composite bearing composed of the upper permanent magnet (2), the fixed frame lower permanent magnet (8), the moving frame combined magnet (6), and the superconducting magnet (13) is the second-level vibration isolation system, used to suppress low-frequency vibration. The first-level vibration isolation system and the second-level vibration isolation system form a two-level vibration isolation system, which is used to achieve ultra-static stability of the optical load (18).

3. The ultra-statically stable rotary scanning imaging satellite platform based on a superconducting magnetic levitation bearing as described in claim 1, characterized in that, The rotating load is an "I"-shaped structure composed of two compartments: the moving frame central shaft (3), the rotating load compartment (1), and the attitude control compartment (4). The attitude control flywheel (5) installed in the attitude control compartment (4) controls the rotation speed of the rotating load through momentum output control. The "I"-shaped structure avoids electromagnetic disturbance of the attitude control flywheel (5) to the optical load (18) in the rotating load compartment (1). In addition, the dual-compartment configuration facilitates the installation and position adjustment of the optical load (18).

4. The ultra-statically stable rotary scanning imaging satellite platform based on a superconducting magnetic levitation bearing as described in claim 1, characterized in that, The attitude control cabin (4) of the rotating load is submerged in the satellite superconducting bearing cavity (10) of the satellite body (11). The attitude control cabin (4) and the satellite body (11) overlap in volume, reducing the distance between the overall center of mass of the rotating load and the center of mass of the satellite body (11), and reducing the influence of inertial force.

5. The ultra-statically stable rotary scanning imaging satellite platform based on a superconducting magnetic levitation bearing as described in claim 1, characterized in that, The copper chain cooling sample rack (14) uses a copper braided cold chain (14-2) to connect the superconductor sample rack and the cold finger connector (14-3). The copper chain cooling sample rack (14) directs the heat of the superconducting magnet (13) to the micro-crystal (16). The micro-crystal (16) and the superconducting magnet (13) do not have direct hard contact, so as to avoid the micro-crystal (16) transmitting vibrations to the superconducting magnet (13).

6. The ultra-statically stable rotary scanning imaging satellite platform based on a superconducting magnetic levitation bearing as described in claim 1, characterized in that, When the rotating load chamber (1) is suspended and stable, the permanent magnet bearing composed of the permanent magnet on the moving frame (2) and the permanent magnet on the fixed frame (8) provides an upward repulsive force F to the rotating load chamber (1). PM The superconducting bearing, composed of the moving frame combined magnet (6) and the superconducting magnet (13), provides a downward attractive force F to the attitude control cabin (4). HTS L1 represents the air gap of the magnetic levitation permanent magnet bearing, and L2 represents the air gap of the superconducting bearing. The conditions for the stable suspension of the rotating load chamber (1) need to be met: That is, the repulsive force of the permanent magnet bearing is equal to the attractive force of the superconducting bearing. At the same time, the superconducting magnetic levitation composite bearing needs to maintain stability with a stiffness of less than that of the superconducting bearing. The rotating load chamber (1) and the attitude control chamber (4) are rigidly connected by the central shaft (3) of the moving frame, and dL1 = dL2.

7. The ultra-statically stable rotary scanning imaging satellite platform based on a superconducting magnetic levitation bearing as described in claim 1, characterized in that, The moving frame combined magnet (6) includes an outer magnet shell (6-1), an outer magnetic shielding ring (6-2), an outer magnet ring (6-3), a middle magnet ring (6-4), an inner magnet ring (6-5), an inner magnetic shielding ring (6-6), and an upper magnetic shielding plate (6-7). The outer magnet ring (6-3), the middle magnet ring (6-4), and the inner magnet ring (6-5) are made of neodymium iron boron material. The magnetic pole direction of the outer magnet ring (6-3) is radially inward, the magnetic pole direction of the inner magnet ring (6-5) is radially outward, and the middle magnet ring (6-4) is axially downward. The outer magnet ring (6-3) and the inner magnet ring (6-5) adopt an N (N≥12)-lobed fan-shaped magnet splicing ring structure.

8. A rotary scanning imaging ultrastatic stable satellite platform based on a superconducting magnetic levitation bearing as described in claim 1, characterized in that, In actual implementation, the satellite body (11) is tangent to the orbit in the axial direction, and the optical payload (18) rotates 360° along the axial direction to scan. The rotation speed is controlled by the attitude control flywheel (5) with a single degree of freedom. The axis of rotation of the attitude control flywheel (5), the central axis of the moving frame and the optical payload (18) coincide.

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