Zero-gravity unloading method for load platform integrated flexible spacecraft ground test

Abstract

The invention provides a zero-gravity unloading method for a ground test of a load platform integrated flexible spacecraft, and the method comprises the steps: arranging gravity unloading mechanisms, such as an air floatation mechanism and a suspension mechanism, at an optical load primary mirror, an optical load secondary mirror, a central star, a primary mirror section truss, a central star truss and the like of the load platform integrated flexible spacecraft; therefore, the gravity of the spacecraft in a ground test environment is balanced. Compared with the prior art, the method has the advantages that a feasible technical scheme for unloading of a load platform integrated flexible spacecraft ground test is provided, structural deformation of the flexible spacecraft can be effectively controlled, internal force of a spacecraft truss structure in a ground gravity environment is reduced, normal actuation of various mechanisms installed on the truss is ensured, and the reliability of the flexible spacecraft is improved. And normal development of various on-orbit working condition verification of the ground test is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of spacecraft ground testing, and in particular, relates to a zero-gravity unloading device and method for ground testing of a flexible spacecraft with an integrated payload platform. Background Art

[0002] Simulating a micro-low gravity environment under the ground gravity field environment is a necessary condition and key technology for spacecraft ground testing, and will directly affect the overall development level of the spacecraft. For spacecraft operating in orbit, it is necessary to achieve zero-gravity unloading in spacecraft ground testing to simulate the zero-gravity environment in orbit, so as to effectively verify the performance and reliability of the spacecraft. At present, the zero-gravity unloading technology in spacecraft ground testing is mainly used for the deployment test of flexible accessories such as spacecraft solar panels and antennas, the ground comprehensive test of spacecraft rendezvous and docking, and the test of spacecraft hatch opening and closing. Various gravity unloading mechanisms (including flexible suspension, guide rails, booms, air flotation, etc.) are used to balance or adjust the gravity of the test product to achieve the six-degree-of-freedom posture adjustment of the test mechanism.

[0003] However, as space missions become increasingly complex, so too are the configurations and functions of spacecraft, placing increasing demands on zero-gravity unloading technology for ground-based testing. For example, geostationary optical imaging satellites, used for meteorological research, scientific search and rescue, and other activities, require ultra-large-aperture optical payloads. Compared to satellites with separate payload and platform designs, satellites with an integrated payload and platform design offer significant advantages in terms of observation width, spatial resolution, temporal resolution, and observation duration. However, these satellites are highly integrated with the platform structure, employing numerous lightweight, low-damping truss structures to reduce weight. Consequently, their dimensions are large and slender, with insignificant central rigid-body characteristics, high structural flexibility but a low fundamental frequency, and dispersed mass characteristics but densely populated modes. In a ground-based gravity environment, the lack of a balancing and supporting gravity unloading mechanism will cause significant deformation and internal forces in the satellite's truss structure, preventing the various mechanisms mounted on the truss from functioning properly and making it impossible to conduct various on-orbit operational verifications on the ground.

[0004] Patent publication number CN110027732A discloses a zero-gravity unloading device for the assembly and commissioning of lightweight spacecraft components. However, this device is limited in its applicability and cannot meet the requirements of complex configurations. Furthermore, the unloading dimension is limited and it lacks multi-degree-of-freedom posture control. Furthermore, patent publication number CN106005493A, while innovating in vertical constant force output, still fails to meet the core requirements of flexible spacecraft with an integrated payload platform.

[0005] At present, there is no feasible technical solution for zero-gravity unloading in ground tests of such large-scale payload platform integrated flexible spacecraft. Under the existing ground test zero-gravity unloading technical solution, it is still difficult to realize the on-orbit zero-gravity environment simulation of payload platform integrated flexible spacecraft.

[0006] Based on the defects in the above-mentioned prior art, there is an urgent need to develop a zero-gravity unloading device and method for ground testing of a flexible spacecraft with an integrated payload platform. Summary of the Invention

[0007] In view of the defects in the prior art, the purpose of the present invention is to provide a zero-gravity unloading device and method for ground testing of a flexible spacecraft with an integrated payload platform.

[0008] According to the present invention, a zero-gravity unloading device for a payload platform integrated flexible spacecraft ground test is provided, comprising: an optical payload secondary mirror 1, a secondary mirror segment truss 2, a central star 3, a central star truss 4, a primary mirror segment truss 10, and an optical payload primary mirror 11;

[0009] The secondary mirror segment truss 2 respectively connects the optical payload secondary mirror 1 and the central star 3, the cabins of the central star 3 are interconnected by the central star truss 4, and the primary mirror segment truss 10 respectively connects the optical payload primary mirror 11 and the central star 3.

[0010] Preferably, it further includes: a macro-micro actuator 8; and other payload units 5 other than the optical payload secondary mirror 1 and the optical payload primary mirror 11;

[0011] The macro-micro actuator 8 is arranged on the primary mirror segment truss 10 and is used to adjust the position and posture of the optical payload primary mirror 11; other payload units 5 are arranged in the cabin of the central star body 3.

[0012] Preferably, the optical load secondary mirror 1, the secondary mirror segment truss 2, the central star 3 and the central star truss 4 form a triangular pyramid configuration; the optical load primary mirror 11, the primary mirror segment truss 10, the central star 3 and the central star truss 4 form a triangular prism configuration.

[0013] Preferably, the secondary mirror segment truss 2, the primary mirror segment truss 10 and the central star body truss 4 are all composed of truss cells of a triangular prism configuration.

[0014] Preferably, the number of the secondary mirror segment trusses 2 is the same as that of the primary mirror segment trusses 10 , which is N, and N≥3.

[0015] Preferably, the payload platform integrated flexible spacecraft uses both air flotation and suspension to balance the gravity of the entire spacecraft.

[0016] Preferably, when the air flotation method is adopted, an optical payload secondary mirror air flotation 14 is arranged at the bottom of the optical payload secondary mirror 1, two central star body air flotations 13 are arranged in the cabin at the bottom of the central star body 3, a primary mirror segment truss air flotation 9 is arranged at the midpoint of the primary mirror segment truss 10 along the length direction, and an optical payload primary mirror air flotation 12 is arranged at the bottom of the optical payload primary mirror 11;

[0017] The primary mirror segment truss air float 9, the optical payload primary mirror air float 12, the central star air float 13, and the optical payload secondary mirror air float 14 can respectively effectively support the primary mirror segment truss 10, the optical payload primary mirror 11, the central star 3, and the optical payload secondary mirror 1, balance the gravity exerted on the above components, the secondary mirror segment truss 2, the central star truss 4, other payload units 5, and the macro-micro actuator 8 under the ground test gravity environment, and control the structural deformation of the secondary mirror segment truss 2 and the primary mirror segment truss 10;

[0018] When the suspension method is adopted, the cabin on the upper part of the central satellite 3 is provided with a central satellite cabin suspension 6, and the suspension point of the central satellite truss 4 is provided with a central satellite truss suspension 7, which coincides with the center of mass of the entire satellite;

[0019] The central star body cabin suspension 6 and the central star body truss suspension 7 can be used to assist the central star body truss 4 in supporting and connecting the cabin of the central star body 3, balance the gravity of other load units 5 arranged in the cabin of the central star body 3, reduce the relative displacement of the cabin of the central star body 3, and effectively reduce the large deformation and internal force of the secondary mirror segment truss 2 and the primary mirror segment truss 10 respectively connected to the cabin of the central star body 3 due to relative displacement.

[0020] According to a zero-gravity unloading method for a ground test of a payload platform-integrated flexible spacecraft provided by the present invention, a finite element model of unloading for the ground test of the payload platform-integrated flexible spacecraft is established to obtain simulation results, analyze the impact of the zero-gravity unloading method on the internal force of the primary mirror segment truss 10 of the payload platform-integrated flexible spacecraft, evaluate whether the macro-micro actuator 8 arranged on the primary mirror segment truss 10 can be actuated normally, and verify the effectiveness of the zero-gravity unloading method, including the following steps:

[0021] Step 1: Arrange the unloading mechanism, install the air flotation system and suspension system, and adjust the entire satellite's posture;

[0022] Step 2: Simulation verification: Establish a finite element model and set unloading constraints;

[0023] Step 3: Conduct internal force analysis and verification: generate a simulation cloud diagram and compare the unloading schemes.

[0024] Preferably, the simulation verification in step 2 includes:

[0025] Other payload units 5 are treated equivalently in the form of uniformly distributed mass or mass points; the optical payload primary mirror 11, the optical payload secondary mirror 1, the central star 3, and the triangular plates in various truss cells are modeled with shell elements, and the truss rods are modeled with beam elements; the macro-micro actuators 8 are respectively arranged in the first and seventh triangular prism truss cells close to the central star 3 in the three primary mirror segment trusses 10; the entire satellite length of the payload platform integrated flexible spacecraft is 7m, and the diameter of the optical payload primary mirror 11 is 1.3m; the optical payload primary mirror 11 and the optical payload secondary mirror 1 are made of wood, and the secondary mirror segment truss 2, the central star 3, the central star truss 4, and the primary mirror segment truss 10 are made of aluminum alloy;

[0026] Several air floats are set up for the optical payload secondary mirror 1, the central star 3, the primary mirror segment truss 10, and the optical payload primary mirror 11. In the model, the above-mentioned air floats are simplified to displacement constraints, which constrain the translational freedom of the air float support point along the Y direction, the rotational freedom around the X axis, and the rotational freedom around the Z axis, that is, U2=UR1=UR3=0. The suspension of the central star truss 4 is simplified to displacement constraints in the model, which constrain the translational freedom of the central star truss 4 suspension point in the Y direction, the rotational freedom around the X axis, and the rotational freedom around the Z axis, that is, U2=UR1=UR3=0. The suspension of the central star 3 cabin is simplified to displacement constraints in the model, which constrains the translational freedom of the central star 3 cabin suspension point along the X, Y and Z directions, that is, U1=U2=U3=0. A gravitational acceleration is applied along the Y direction of the entire star, and its value is set to 9800mm / s 2 , to simulate the gravity environment of ground tests.

[0027] Preferably, the internal force analysis and verification in step 3 includes:

[0028] According to the internal forces / axial forces of the rod structures of the secondary mirror segment truss 2, the central body truss 4 and the primary mirror segment truss 10 of the integrated flexible spacecraft of the payload platform, as well as the internal forces / axial forces of the first and seventh triangular prism truss cell rods arranged in the three primary mirror segment trusses 10 close to the central body 3, a simulation cloud map can be formed to judge the effectiveness of the zero-gravity unloading method.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention has formed a feasible technical solution for zero-gravity unloading of ground tests on flexible spacecraft with integrated large-scale payload platforms. The zero-gravity unloading method can effectively control the structural deformation of flexible spacecraft with integrated payload platforms, thereby reducing the internal forces of the spacecraft truss structure under the ground gravity environment, ensuring the normal operation of various mechanisms installed on the truss, and ensuring the normal implementation of various on-orbit working condition verifications in ground tests.

[0031] 2. The present invention realizes multi-point, multi-mode and coordinated unloading through an unloading method that combines air flotation and suspension. It balances the gravity distribution of the entire satellite more effectively than a single unloading method and suppresses complex deformation modes.

[0032] 3. The present invention has a stable structure and high reliability. By setting a suspension on the central star body, the bottom of the primary mirror, the bottom of the secondary mirror and the midpoint of the mirror segment truss supporting them are air-floated, which reduces the displacement and deformation caused by gravity and further supports and stabilizes the overall structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0034] Figure 1 Schematic diagram of the zero-gravity unloading device structure for ground testing of a flexible spacecraft with integrated payload platform;

[0035] Figure 2 Schematic diagram of the finite element model of the zero-gravity unloading method for the ground test of the payload-platform integrated flexible spacecraft;

[0036] Figure 3 Finite element simulation cloud diagram of the zero-gravity unloading method for the ground test of the payload-platform integrated flexible spacecraft.

[0037] The figure shows:

[0038]

[0039] DETAILED DESCRIPTION

[0040] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0041] Example 1

[0042] like Figure 1As shown, the payload platform integrated flexible spacecraft includes: an optical payload secondary mirror 1, a secondary mirror segment truss 2, a central body 3, a central body truss 4, other payload units 5, a macro-micro actuator 8, a primary mirror segment truss 10, and an optical payload primary mirror 11. The secondary mirror segment truss 2, the primary mirror segment truss 10, and the central body truss 4 are all primarily composed of truss cells in a triangular prism configuration. The secondary mirror segment truss 2 connects the optical payload secondary mirror 1 and the central body 3. The three compartments of the central body 3 are interconnected by the central body truss 4. The primary mirror segment truss 10 connects the optical payload primary mirror 11 and the central body 3. The optical payload secondary mirror 1, the secondary mirror segment truss 2, the central body 3, and the central body truss 4 form a triangular pyramid configuration; the optical payload primary mirror 11, the primary mirror segment truss 10, the central body 3, and the central body truss 4 form a triangular prism configuration. The macro-micro actuator 8 is arranged on the primary mirror segment truss 10 , and the other payload units 5 are arranged on the three cabins of the central satellite 3 .

[0043] The zero-gravity unloading method, based on the aforementioned payload platform integrated flexible spacecraft configuration, utilizes both air flotation and suspension to balance the entire satellite's gravity. On one hand, an optical payload secondary mirror air flotation 14 is positioned at the base of the optical payload secondary mirror 1, two central body air flotations 13 are positioned in a cabin at the base of the central body 3, a primary mirror segment truss air flotation 9 is positioned at each of the three primary mirror segment trusses 10 along their lengthwise midpoints, and an optical payload primary mirror air flotation 12 is positioned at the base of the optical payload primary mirror 11. The primary mirror segment truss air flotations 9, optical payload primary mirror air flotation 12, central body air flotation 13, and optical payload secondary mirror air flotation 14 are capable of effectively supporting the primary mirror segment trusses 10, optical payload primary mirror 11, central body 3, and optical payload secondary mirror 1, respectively. These components, as well as the secondary mirror segment trusses 2, central body trusses 4, other payload units 5, and macro / micro actuators 8, are balanced under the ground test gravity environment, controlling the structural deformation of the secondary mirror segment trusses 2 and primary mirror segment trusses 10. On the other hand, the two cabins on the upper part of the central satellite 3 are equipped with four central satellite cabin suspensions 6, and a central satellite truss suspension 7 is arranged at the suspension point of the central satellite truss 4, which coincides with the center of mass of the entire satellite. Since the output force of the macro-micro actuator 8 and other mechanisms arranged on the primary mirror segment truss 10 has an upper limit, the central satellite cabin suspension 6 and the central satellite truss suspension 7 can be used to assist the central satellite truss 4 in supporting and connecting the three cabins of the central satellite 3, balancing the gravity of other load units 5 arranged on the three cabins of the central satellite 3, reducing the relative displacement of the three cabins of the central satellite 3, and effectively reducing the large deformation and internal force of the secondary mirror segment truss 2 and the primary mirror segment truss 10 connected to the three cabins of the central satellite 3 due to relative displacement, ensuring the normal operation of the macro-micro actuator 8 installed on the primary mirror segment truss 10, and ensuring the normal implementation of various on-orbit working condition verifications in ground tests.

[0044] Example 2

[0045] According to the payload platform integrated flexible spacecraft configuration and the zero-gravity unloading method of the ground test thereof described in Example 1 of the present invention, a force unloading finite element model of the ground test of the payload platform integrated flexible spacecraft is established. According to the finite element simulation results, the influence of the zero-gravity unloading method described in Example 1 of the present invention on the internal force of the main mirror segment truss 10 of the payload platform integrated flexible spacecraft under the gravity environment of the ground test is analyzed, and this is used to evaluate whether the macro-micro actuator 8 arranged on the main mirror segment truss 10 can operate normally, so as to verify the effectiveness of the zero-gravity unloading method described in Example 1 of the present invention.

[0046] The unloading finite element model of the payload platform integrated flexible spacecraft ground test described in Example 2 of the present invention is as follows: Figure 2 As shown. According to the payload platform integrated flexible spacecraft configuration described in Example 1 of the present invention, the specific structure will be ignored during modeling, and other payload units 5 will be treated equivalently in the form of uniformly distributed mass or mass points; the optical payload primary mirror 11, the optical payload secondary mirror 1, the central star 3, and the triangular plates in various truss cells are modeled with shell units, and the truss rods are modeled with beam units; when meshing the model, it is necessary to properly control the number of grids, taking into account both the model calculation accuracy and the amount of calculation. In addition, in Example 2 of the present invention, the macro-micro actuators 8 are respectively arranged in the first and seventh triangular prism truss cells close to the central star 3 in the three primary mirror segment trusses 10. The entire satellite length of the payload platform integrated flexible spacecraft is 7m, and the diameter of the optical payload primary mirror 11 is 1.3m. The optical payload primary mirror 11 and the optical payload secondary mirror 1 are made of wood, and the secondary mirror segment truss 2, the central star 3, the central star truss 4, and the primary mirror segment truss 10 are made of aluminum alloy.

[0047] The material properties of wood are shown in the table below:

[0048]

[0049] The material properties of aluminum alloy are shown in the following table:

[0050]

[0051]

[0052] According to the zero-gravity unloading method for the ground test of the payload platform integrated flexible spacecraft described in Example 1 of the present invention, the optical payload secondary mirror 1, the central star body 3, the primary mirror segment truss 10, and the optical payload primary mirror 11 of the unloading finite element model of the ground test of the payload platform integrated flexible spacecraft described in Example 2 of the present invention are provided with several air floats. In the model, the air bearing is simplified to a displacement constraint, constraining the air bearing support point's translational freedom U2 in the Y direction, rotational freedom UR1 around the X axis, and rotational freedom UR3 around the Z axis, i.e., U2 = UR1 = UR3 = 0. The central satellite truss 4 suspension is simplified to a displacement constraint in the model, constraining the central satellite truss 4 suspension point's translational freedom U2 in the Y direction, rotational freedom UR1 around the X axis, and rotational freedom UR3 around the Z axis, i.e., U2 = UR1 = UR3 = 0. The central satellite 3 cabin suspension is simplified to a displacement constraint in the model, constraining the central satellite 3 cabin suspension point's translational freedom U1, U2, and U3 in the X, Y, and Z directions, i.e., U1 = U2 = U3 = 0. A gravitational acceleration is applied along the entire satellite's Y direction, set to 9800 mm / s. 2 , to simulate the gravity environment of ground tests.

[0053] For the unloading finite element model of the ground test of the payload platform integrated flexible spacecraft described in Example 2 of the present invention, an implicit static analysis task is established and submitted for calculation, and the influence of the zero-gravity unloading method described in Example 1 of the present invention on the internal force of the main mirror segment truss 10 of the payload platform integrated flexible spacecraft is analyzed. This is used to evaluate whether the macro-micro actuator 8 arranged on the main mirror segment truss 10 can operate normally, so as to verify the effectiveness of the zero-gravity unloading method described in Example 1 of the present invention.

[0054] Regarding Example 2 of the present invention, Figure 3 The effects of two unloading schemes were compared, as follows: Scheme 1 is to set up optical payload secondary mirror air floatation 14, optical payload primary mirror air floatation 12, and central star body truss suspension 7; Scheme 2 is based on the zero-gravity unloading method of the payload platform integrated flexible spacecraft ground test described in Example 1 of the present invention, and sets up air floatation and suspension.

[0055] Figure 3The simulation cloud diagram shows the internal force and axial force distribution of the payload platform integrated flexible spacecraft secondary mirror segment truss 2, central body truss 4, and primary mirror segment truss 10, as well as the internal force and axial force of the first and seventh triangular prism truss cell members arranged near the central body 3 in the three primary mirror segment trusses 10. According to the simulation results, the maximum axial force SF1 of each truss member in Scheme 1 is -461.125N, of which the maximum axial force of the truss member at the installation location of the macro-micro actuator 8 is 83.424N. In Scheme 2, the maximum axial force of each truss member is -408.920N, of which the maximum axial force of the truss member at the installation location of the macro-micro actuator 8 is 18.501N, a 77.82% reduction in peak axial force. It can be seen from the above simulation results that after adopting the zero-gravity unloading method of the payload platform integrated flexible spacecraft ground test described in Example 1 of the present invention, the maximum axial force of the truss rod at the installation location of the macro-micro actuator 8 is greatly reduced by 77.82%, to only 18.501N, which is far lower than the output force upper limit of 70N of the macro-micro actuator 8 described in the present invention. Therefore, the macro-micro actuator 8 arranged on the primary mirror segment truss 10 can operate normally, which shows that the zero-gravity unloading method described in Example 1 of the present invention is effective.

[0056] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0057] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A zero-gravity unloading device for ground testing of a flexible spacecraft with an integrated payload platform, characterized in that: include: An optical payload secondary mirror (1), a secondary mirror segment truss (2), a central star (3), a central star truss (4), a primary mirror segment truss (10), and an optical payload primary mirror (11); The secondary mirror segment trusses (2) are respectively connected to the optical payload secondary mirror (1) and the central star (3); the cabins of the central star (3) are mutually connected by the central star trusses (4); and the primary mirror segment trusses (10) are respectively connected to the optical payload primary mirror (11) and the central star (3).

2. The zero-gravity unloading device for ground testing of a flexible spacecraft with an integrated payload platform according to claim 1, characterized in that: Also includes: A macro-micro actuator (8); and also includes other load units (5) other than the optical load secondary mirror (1) and the optical load primary mirror (11); The macro-micro actuator (8) is arranged on the primary mirror segment truss (10) and is used to adjust the position and posture of the optical payload primary mirror (11); other payload units (5) are arranged on the cabin of the central star (3).

3. The zero-gravity unloading device for ground testing of a flexible spacecraft with an integrated payload platform according to claim 1, characterized in that: The optical load secondary mirror (1), the secondary mirror segment truss (2), the central star (3) and the central star truss (4) form a triangular pyramid configuration; the optical load primary mirror (11), the primary mirror segment truss (10), the central star (3) and the central star truss (4) form a triangular prism configuration.

4. The zero-gravity unloading device for ground testing of a flexible spacecraft with an integrated payload platform according to claim 1, characterized in that: The secondary mirror segment truss (2), the primary mirror segment truss (10) and the central star body truss (4) are all composed of truss cells with a triangular prism configuration.

5. The zero-gravity unloading device for ground testing of a flexible spacecraft with an integrated payload platform according to claim 1, characterized in that: The number of the secondary mirror segment trusses (2) is the same as that of the primary mirror segment trusses (10), which is N, where N≥3.

6. The zero-gravity unloading device for ground testing of a flexible spacecraft with an integrated payload platform according to claim 1, characterized in that: The payload platform integrated flexible spacecraft uses air flotation and suspension to balance the gravity of the entire satellite.

7. The zero-gravity unloading device for ground testing of a flexible spacecraft with an integrated payload platform according to claim 6, characterized in that: When the air flotation method is adopted, an optical payload secondary mirror air flotation (14) is arranged at the bottom of the optical payload secondary mirror (1), two central star body air flotations (13) are arranged at the cabin at the bottom of the central star body (3), a primary mirror segment truss air flotation (9) is arranged at the midpoint of the primary mirror segment truss (10) along the length direction, and an optical payload primary mirror air flotation (12) is arranged at the bottom of the optical payload primary mirror (11); The primary mirror segment truss air float (9), the optical payload primary mirror air float (12), the central star body air float (13), and the optical payload secondary mirror air float (14) can respectively and effectively support the primary mirror segment truss (10), the optical payload primary mirror (11), the central star body (3), and the optical payload secondary mirror (1), balance the gravity exerted on the above components, the secondary mirror segment truss (2), the central star body truss (4), other single payload units (5), and the macro-micro actuator (8) under the ground test gravity environment, and control the structural deformation of the secondary mirror segment truss (2) and the primary mirror segment truss (10); When the suspension method is adopted, the cabin on the upper part of the central satellite (3) is provided with a central satellite cabin suspension (6), and the suspension point at the central satellite truss (4) is provided with a central satellite truss suspension (7), and the suspension point coincides with the mass center of the entire satellite; The central star body cabin suspension (6) and the central star body truss suspension (7) can be used to assist the central star body truss (4) in supporting and connecting the cabin of the central star body (3), balance the gravity of other load units (5) arranged in the cabin of the central star body (3), reduce the relative displacement of the cabin of the central star body (3), and effectively reduce the large deformation and internal force of the secondary mirror segment truss (2) and the primary mirror segment truss (10) respectively connected to the cabin of the central star body (3) caused by the relative displacement.

8. A zero-gravity unloading method for ground testing of a flexible spacecraft with an integrated payload platform, characterized in that: By establishing an unloading finite element model of a ground test of a payload platform integrated flexible spacecraft, obtaining simulation results, analyzing the influence of the zero-gravity unloading method on the internal force of the primary mirror segment truss (10) of the payload platform integrated flexible spacecraft, evaluating whether the macro-micro actuator (8) arranged on the primary mirror segment truss (10) can operate normally, and verifying the effectiveness of the zero-gravity unloading method, the method includes the following steps: Step 1: Arrange the unloading mechanism, install the air flotation system and suspension system, and adjust the entire satellite's posture; Step 2: Simulation verification: Establish a finite element model and set unloading constraints; Step 3: Conduct internal force analysis and verification: generate a simulation cloud diagram and compare the unloading schemes.

9. The zero-gravity unloading method for ground testing of a payload-platform integrated flexible spacecraft according to claim 8, characterized in that: The simulation verification in step 2 includes: Other payload units (5) are treated equivalently in the form of uniformly distributed masses or mass points; the optical payload primary mirror (11), the optical payload secondary mirror (1), the central star (3) and the triangular plates in various truss cells are modeled with shell units, and the truss rods are modeled with beam units; the macro-micro actuators (8) are respectively arranged in the first and seventh triangular prism truss cells close to the central star (3) in the three primary mirror segment trusses (10); the entire satellite length of the payload platform integrated flexible spacecraft is 7m, and the diameter of the optical payload primary mirror (11) is 1.3m; the optical payload primary mirror (11) and the optical payload secondary mirror (1) are made of wood, and the secondary mirror segment truss (2), the central star (3), the central star truss (4) and the primary mirror segment truss (10) are made of aluminum alloy; The optical payload secondary mirror (1), the central star (3), the primary mirror segment truss (10), and the optical payload primary mirror (11) are provided with a number of air floats. In the model, the air floats are simplified to displacement constraints, which constrain the air float support point's translational freedom along the Y direction, the rotational freedom around the X axis, and the rotational freedom around the Z axis, i.e., U2=UR1=UR3=0. The central star truss (4) is suspended in the model as a displacement constraint, which constrains the central star truss (4) suspension point's translational freedom along the Y direction, the rotational freedom around the X axis, and the rotational freedom around the Z axis, i.e., U2=UR1=UR3=0. The central star (3) cabin suspension is simplified to displacement constraints in the model, which constrains the central star (3) cabin suspension point's translational freedom along the X, Y, and Z directions, i.e., U1=U2=U3=0. A gravity acceleration is applied along the Y direction of the entire star, and its value is set to 9800 mm / s. 2 , to simulate the gravity environment of ground tests.

10. The zero-gravity unloading method for ground testing of a payload-platform integrated flexible spacecraft according to claim 8, characterized in that: The internal force analysis and verification in step 3 includes: According to the internal forces / axial forces of the rod structures of the secondary mirror segment truss (2), the central body truss (4) and the primary mirror segment truss (10) of the integrated flexible spacecraft of the payload platform, and the internal forces / axial forces of the first and seventh triangular prism truss cell rods arranged in the three primary mirror segment trusses (10) close to the central body (3), a simulation cloud map can be formed to judge the effectiveness of the zero-gravity unloading method.

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