CN109188648B

CN109188648B - Floating support device for unloading space optical load ground gravity

Info

Publication number: CN109188648B
Application number: CN201811057137.5A
Authority: CN
Inventors: 何煦; 杨雪; 张晓辉; 董吉洪
Original assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Current assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Priority date: 2018-09-11
Filing date: 2018-09-11
Publication date: 2020-05-15
Anticipated expiration: 2038-09-11
Also published as: CN109188648A

Abstract

The invention relates to the technical field of precision machinery and space optics, and particularly discloses a floating support mechanism for ground gravity unloading of a space optical load, which comprises an unloading base, a plurality of groups of gravity unloading devices arranged on the unloading base, and a gravity unloading device fixedly arranged below the optical load; the floating support device also comprises a plurality of groups of fixed support devices arranged on the back of the optical load, and gravity unloading along the gravity vector direction can be realized through the gravity unloading device, so that the maximum deformation of a large-scale optical-mechanical structure introduced by gravity is counteracted, the influence of the inconsistency of the space-ground mechanical environment on the ground installation and adjustment precision and the on-orbit imaging quality of the space optical load is greatly relieved, and the basic image quality is provided for the pre-installation and active optical correction of the ground high-sensitivity optical-sensitive component. In addition, through ground gravity unloading, unnecessary design redundancy of a large-caliber optical load optical-mechanical structure can be greatly reduced, and emission cost and the use efficiency of a space carrier are reduced.

Description

Floating support device for unloading space optical load ground gravity

Technical Field

The invention relates to the technical field of precision machinery and space optics, in particular to a floating support mechanism for ground gravity unloading of a large-caliber space optical load.

Background

The space optical telescope is a space optical load which is carried on a satellite platform and used for imaging and measuring various astronomical phenomena in the universe or carrying out push-broom or staring observation on a ground scenery target. Such space optical telescopes are carried on earth observation satellites, such as the well-known Hubbo telescope and WordView, and are used for optically imaging various astronomy phenomena or ground scenery. All kinds of space optical loads finally work in the space microgravity environment, but the adjustment and the test of the optical loads are carried out on the ground, and the gravity is accompanied with the whole adjustment test process. This results in the mechanical environment of the space optical load adjustment and test process being inconsistent with the actual on-orbit state mechanical environment. The inconsistency of the "space-ground" mechanical environment brings great risk to the realization and long-term stability of the main optical performance of the space optical load. The main reason is that the main performance of a space optical telescope is its optical imaging quality. While the guarantee of the imaging quality depends on the one hand on the optical design residual and on the accuracy of the optical manufacturing and processing. On the other hand, the ground installation and adjustment precision and the structural stability of the optical-mechanical system determine the ground installation and adjustment precision. In the adjusting process, certain image quality evaluation standard is used as a criterion and a pointer to guide an adjusting person to adjust each optical element in the telescope to a given spatial position and posture of an optical design, and the adjusting residual error is ensured to be smaller than an allocated threshold value. The optical-mechanical structure and the thermal control system need to ensure that the installation and adjustment result has long-term stability, so that the space optical load has design performance in the whole working life. However, during the ground installation and adjustment process, gravity always acts on each optical element, supporting truss, instrument module and the like in the optical-mechanical load. The position and the posture of the optical-mechanical assembly are adjusted and positioned under the micro elastic deformation caused by gravity. After the rail gravity is released, elastic deformation recovery and assembly stress release are caused, and then the relative positions and postures of each optical unit and each component are changed, so that the imaging quality of the space optical load is greatly changed.

For medium and small aperture space optical loads, the risk of the above-mentioned "space-ground" mechanical environment inconsistency causing deterioration of the main optical performance of the space optical load is not significant. For medium and small caliber optical loads, the requirements on the weight and the volume of a necessary optical machine structure are not high. On the premise of a certain total mass of emission and carrying, the structural rigidity of the optical-mechanical system can be improved by increasing design redundancy, so that the optical-mechanical assembly has strong capability of resisting gravity deformation, and relatively small variation of optical elements caused by 'springback' of the optical-mechanical structure under the action of gravity and under the condition of zero gravity on rails is ensured, and the imaging quality of the system cannot be changed.

In order to improve the observation resolution and the detection depth and obtain more details of the target space appearance characteristics, the caliber of the space optical telescope is larger and larger, and the space optical telescope has to have a longer focal length. In order to ensure the imaging quality and the optical load under the on-orbit environment, the main performance of the on-orbit stability is long-term, so that the necessary weight and volume of the structure are continuously increased. However, the large-aperture space telescope and the satellite platform thereof are required to be carried on vehicles such as rockets or space shuttles and the like to be launched into orbit, and the vehicles have limited carrying capacity. If the traditional idea of improving the structural rigidity by increasing design redundancy to overcome the inconsistency of the space-ground mechanical environment is still based on the prior art, the total mass of the optical load is inevitably caused to exceed the limit carrying capacity of the spacecraft, and unnecessary emission cost is caused. The corresponding solution is to simulate the mechanical environment similar to the optical load on-track state in the process of ground installation, adjustment and test so as to achieve the effect of relieving the inconsistency of the 'sky-ground' mechanical environment. However, the existing test technology and support method are difficult to meet the above-mentioned mechanical environment simulation requirement of large-caliber space optical load, and can not accurately determine whether the optical machine component is installed and adjusted in place after gravity unloading, mainly for the following reasons.

(1) The existing gravity unloading method mainly comprises two main ideas of full unloading and partial unloading. The full unloading thought mostly adopts the implementation modes of a tower falling method, an airplane parabolic flight method and the like so as to simulate the omnidirectional weightlessness of each dimension of the carried objects. However, the installation and adjustment and test period of the large-caliber space optical load is long, various verification tests need to be inserted in the period, and a large amount of optical test and auxiliary installation and adjustment equipment with large volume and weight are needed. Therefore, the existing omnidirectional weightlessness simulation method is difficult to meet the requirements of large-caliber space optical load adjustment and gravity unloading in the test process.

(2) The other weightless environment simulation idea is to carry out the unloading of the omnidirectional and partial gravity, and the most main simulation mode is to soak the unloaded object in a heavy water tank and counteract partial gravity field effect through liquid buoyancy so as to achieve the aim of omnidirectional and partial unloading. However, the installation and testing process of the space optical load always requires the transmission of optical signals in the installation and testing optical path. The difference between the refractive index of the liquid and both vacuum and air is large, and in addition, a large number of complicated sealing and waterproof designs are required for avoiding the corrosion of the photoelectric imaging device and other circuit systems by the suspension. Therefore, from the aspects of feasibility, cost and the like, the existing omnidirectional part gravity unloading technology is difficult to meet the microgravity simulation requirement in the large-caliber space optical load debugging test process.

(3) In the process of assembling, adjusting and testing the space optical load, assembling stress and elastic deformation introduced by gravity mostly exist only along the direction of a gravity vector, and after the gravity of the rail is released, the stress change in the direction obviously influences the relative pose of each optical assembly. Based on the characteristics, a non-omnidirectional gravity unloading technical idea also exists. The main idea is that the gravity effect along the gravity vector direction is counteracted by an air floatation or multi-point actuating support mode, and the effect of compensating the elastic deformation and the assembly stress along the gravity vector direction is achieved. However, the prior art is directed to a shell with large rigidity or a symmetrical structure, and the unloading residual error is large. The large-caliber space optical load, particularly the space optical load adopting an off-axis light path, has the characteristics of lower structural rigidity, asymmetric mass distribution, larger deviation of a geometric center and a mass center, extremely sensitive installation and adjustment precision to unloading residual errors and the like. In addition, the relative clearance between optical machine components in the large-diameter space optical load needs to be adjusted to the order of wavelength and angular seconds. The existing non-omnidirectional gravity unloading technology is difficult to meet the requirements in the aspects of unloading precision and application conditions.

(4) The ground installation and adjustment testing process of the large-caliber space optical load needs to be verified by vacuum and cold black environment tests. Therefore, the special test environment of the space load also puts forward special requirements on the gravity unloading device, so that the currently generally adopted non-omnidirectional and low-rigidity gravity unloading technology such as air floatation and the like can not meet the requirements of the use environment.

Disclosure of Invention

The invention aims to overcome the defects that the position and the attitude of an optical element are changed and the imaging quality is low due to the fact that internal deformation caused by gravity in the process of installing and adjusting a large-caliber long-focus space optical telescope on the ground and testing can rebound after the gravity of an orbit is released.

In order to achieve the above object, the present invention provides a floating support device for ground gravity unloading of space optical loads, which comprises a base, a plurality of groups of gravity unloading devices arranged on the base, and a gravity unloading device fixedly arranged below the optical loads; the floating support device also comprises a plurality of groups of fixed support devices arranged on the back of the optical load.

Furthermore, the gravity unloading device comprises a gravity unloading component base, a vertical freedom degree release component, a force transmission mechanism, a tension sensor and a five-freedom degree release component; the gravity unloading assembly base is fixedly arranged on the base, one end of the vertical freedom degree releasing assembly is connected with the gravity unloading assembly base, and the other end of the vertical freedom degree releasing assembly is connected with the tension sensor through a connecting plate; one end of the five-freedom-degree release assembly is connected with a tension sensor, the other end of the five-freedom-degree release assembly is connected with the optical load, and the tension sensor is used for measuring the pressure and the pulling force inside the gravity unloading device.

Preferably, the five-degree-of-freedom release assembly comprises a ball bearing assembly and a thrust shafting assembly which are connected with the optical load, one end of the ball bearing assembly is connected with the unloading connecting seat in series, and the other end of the ball bearing assembly is connected with the thrust shafting assembly in series.

Preferably, the ball bearing assembly comprises a ball bearing, a ball bearing seat and a ball bearing pressing plate, the ball bearing is installed in the ball bearing seat, and the ball bearing pressing plate provides pre-pressure.

Preferably, the thrust shafting component comprises a thrust ring, a steel ball, a retainer and a thrust bearing seat, the thrust ring is fixedly connected with the ball bearing seat, and an annular gap is arranged between the retainer and the thrust bearing seat.

Preferably, the vertical degree of freedom release assembly comprises a lifting connecting plate and a movable pulley block assembly, the lifting connecting plate is fixedly arranged at the bottom end of the force transmission mechanism, and two sides of the lifting connecting plate are fixedly connected with the movable pulley block assembly respectively.

The gravity unloading assembly further comprises a static pulley block assembly, the static pulley block assembly is fixedly arranged on the stand columns on two sides of the gravity unloading assembly base through a static pulley bearing seat, and the movable pulley block assembly is matched with the static pulley block assembly to realize multi-group winding of one steel wire rope.

Furthermore, the movable pulley block assembly comprises a balancing box ball head connecting assembly and a balancing box, wherein two ends of a steel wire rope in the movable pulley block assembly are fixedly connected with the balancing box through the balancing box ball head connecting assembly, and the balancing box ball head connecting assembly can release three-dimensional rotational freedom between the steel wire rope and the balancing box.

Furthermore, a gravity unloading assembly base reinforcing plate is fixedly arranged on the gravity unloading assembly base.

Preferably, the gravity unloading device is provided with four groups, and the fixed supporting device is provided with three groups.

The invention has the beneficial effects that:

1. the gravity unloading device with a special structure is designed, the balancing force transmission is realized based on a pure mechanical mechanism, and the gravity unloading device is matched with a fixed supporting point to realize the space optical load position and posture maintenance.

2. The invention designs an unloading force six-dimensional release mechanism, and the device volume is greatly reduced after the unloading force six-dimensional release mechanism is integrated with a force transmission mechanism. In addition, the layout sequence of the six-dimensional freedom degree release mechanism can effectively reduce the unloading residual error and improve the application precision of the unloading force.

3. The invention utilizes the movable-static pulley block assembly with a special configuration to realize the conversion between the gravity of the balancing object and the unloading force on one hand, and the aim of unloading by 1 time of gravity can be realized only by 1/6 balancing the gravity of the object. Meanwhile, the movable-static pulley block assembly with a special configuration can effectively eliminate additional unbalanced moment caused by processing and assembling errors of the unloading device, so that the loaded unloading force is balanced relative to the force and the moment of a local unloading point. Thirdly, the movable and static pulley block configuration also effectively achieves the purpose of unloading the gravity at the bottom, and further achieves the purpose of reducing the volume and the weight of the device.

4. The gravity unloading technology can solve the problem of microgravity simulation in the process of installing, adjusting and testing the large-caliber space optical load ground. By designing the gravity unloading device with special configuration and layout, the gravity unloading along the gravity vector direction can be realized, thereby offsetting the maximum deformation of the large-scale optical-mechanical structure introduced by gravity, greatly relieving the influence of the inconsistency of the space-ground mechanical environment on the ground installation and adjustment precision of space optical loads and the on-orbit imaging quality, and providing basic image quality for the preassembly and active optical correction of ground high-sensitivity optical chemical components. In addition, through ground gravity unloading, unnecessary design redundancy of a large-caliber optical load optical-mechanical structure can be greatly reduced, and emission cost and the use efficiency of a space carrier are reduced.

5. In addition, the invention has application potential in the aspects of flexibility and self-adaptive support of large thin shell structural parts. Such as large thin-walled carbon fiber cylinders or profiled shells, which require high precision support during winding, machining, assembly, etc. Most of the existing supporting schemes adopt metal molds with similar shapes, so that the flexibility of a production line is reduced, the manufacturing cost and the period are improved, and the bottleneck exists in the aspects of size and processing precision. By utilizing the unloading device involved in the invention, a floating support structure with non-static stability can be formed, the spatial position and posture of the large thin-wall shell can be ensured to be determined in the processing and assembling process, on the other hand, the gravity unloading of the thin-wall shell is realized, and the processing error and the assembling error caused by elastic deformation are eliminated. The invention has wide application prospect in the field of machining and assembling of special material low-rigidity components.

Drawings

Figure 1 schematically shows a working principle diagram according to the invention;

FIG. 2 is a front view of a floating support device for ground gravity unloading of space optical loads in accordance with the present invention;

FIG. 3 is a side view of a floating support device for ground gravity unloading of space optical loads in accordance with the present invention;

FIG. 4 is a schematic view of the construction of a single gravity unloading apparatus of the present invention;

FIG. 5 is a schematic diagram of a single gravity unloading apparatus of the present invention without a gravity unloading assembly base;

fig. 6 is a schematic structural diagram of the movable-static pulley block assembly mechanism of the invention.

1. A first finite element; 2. a second finite element; 3. a first gravity unloading device;

4. a second gravity unloading device; 5. fixing the supporting point; 6. a gravity unloading device;

7. an optical load; 8. a base; 9. fixing the supporting device; 10. unloading the connecting seat;

11. a ball bearing; 12. a ball bearing seat; 13. a ball bearing platen; 14. a thrust pressing plate;

15. a thrust ring; 16. a steel ball; 17. a holder; 18. a thrust bearing seat;

19. a sensor connecting seat; 20. a tension sensor; 21. a strut and a connecting plate thereof;

22. lifting the connecting plate; 23. a leveling box ball head connecting assembly; 24. leveling box;

25. a gravity unloading assembly base stiffener; 26. a gravity unloading assembly base;

27. a movable pulley block assembly; 28. a static pulley block component.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention.

Referring first to fig. 1, illustrating the working principle of the present invention, while providing a given unloading force, the unloading device needs to release the degrees of freedom of six directions of the unloading force vector at the same time, and ensure that the unloading direction of the applied unloading force is always parallel to the gravity vector direction, and the applied unloading force does not change with the change of the loading position and the change of the attitude of the space load. Furthermore, the gravity unloading device should be as compact as possible to meet the spatial size constraints used within the vacuum vessel.

In view of the above, the gravity unloading device according to the present invention has been proposed, and the operation principle thereof is shown in fig. 1. Any part of the spatial optical payload opto-mechanical structure can be divided into adjacent finite elements "1 and 2". Under the condition of no loading and unloading force, the finite element is in a static state under the action of the internal force and the fixed supporting point 5, but elastic deformation delta exists. After the 'first gravity unloading device 3' and the 'second gravity unloading device 4' are fixedly connected with the

finite elements

1 and 2 of a certain part of the optical machine structure, a transient non-statically determinate process exists, because the internal stress along the gravity direction is larger than the resultant force along the gravity direction, and the applied unloading force 6-dimensional freedom degree is completely released, the internal stress between the finite elements introduced by elastic deformation 'delta' can drive the 'first finite element 1' and the 'second finite element 2' to move freely relative to each other, and mutual crosstalk and interference do not exist until the resultant force along the gravity direction is balanced again. In this new equilibrium state, the unload force is equal to the local finite element gravity, and when neglecting computer simulation analysis errors, the elastic deformation "Δ" is close to zero, simulating the microgravity state in the gravity vector direction.

In order to realize the principle, the device provided by the invention is composed as shown in fig. 2 and 3. The space optical load in the integrated and test state is in an optical axis horizontal state, and three 'fixed supporting devices 9' positioned on the back of the space optical load are used for determining the space position and the posture of the optical load to be tested. One end of a plurality of groups of gravity unloading devices 6 is fixedly connected to the bottom plate of the base 8, and the other end of the gravity unloading devices is fixedly connected with the optical load 7, namely the space optical telescope to be measured. The gravity unloading device 6 realizes gravity unloading of the space optical telescope to be tested along the gravity vector direction. Meanwhile, the fixed supporting device 9 rigidly connected to the base 8 determines the pose of the optical telescope in the space to be measured through rigid support, and realizes no stress or micro stress inside the rigid supporting point, thereby ensuring the effectiveness of optical mounting and calibration. The base 8 is a rigid foundation of the gravity unloading device, and has the functions of keeping the relative positions and postures of unloading points and rigidly and fixedly connecting the unloading device and the fixed supporting device.

Fig. 4 and 5 respectively show the composition of a single gravity unloading device, and multiple groups of gravity unloading devices jointly realize multi-point floating gravity unloading. The unloading connecting base 10 and a connecting flange given on the space optical telescope to be tested are positioned by means of screw connection and pin shafts, and complete fixation of the single gravity unloading device 6 and the optical-mechanical structure of the space optical telescope to be tested is realized based on the positioning principle of 'one surface and two pins'. The ball bearing 11 is located in a ball bearing housing 12 and pre-stress is provided by means of a ball bearing pressure plate 13, thereby controlling the sensitivity and deflection of the ball bearing assembly by means of static friction. The assembly "ball bearing 11, ball bearing housing 12 and ball bearing pressure plate 13" constitutes a spherical bearing assembly that releases the relative degrees of freedom in three rotational directions between the unloader socket 10 and thrust collar 15 in series therewith. The thrust ring 15 is fixedly connected with the ball bearing seat 12 and forms a thrust shafting with the thrust pressure plate 14, the steel ball 16 and the thrust bearing seat 18. The retainer 17 is used for positioning the steel balls to prevent the relative movement between the steel balls in the freedom degree releasing process, and on the other hand, the free movement in any translation direction in the horizontal plane is realized by virtue of an annular gap between the retainer 17 and the thrust bearing seat 18, so that the two-dimensional translation freedom degree is released. The above-mentioned components "10" to "18" constitute a five-degree-of-freedom release component, which is connected in series with a tension sensor 20 through a sensor connecting seat 19. The tension sensor 20 is a vacuum compatible device, can measure the pressure and the pulling force inside the unloading device in real time, and feeds back the pressure and the pulling force in a numerical form in real time through a cable, so that a basis is provided for quantitatively judging the internal mechanical state of the gravity unloading device. Meanwhile, the tension sensor 20 is positioned between the final stage of the unloading force transmission path and the five-degree-of-freedom release assembly, so that the coupling effect of the unloading force and the friction force in the unloading force transmission path can be integrally measured, and the unloading force measurement error caused by the movement of the five-degree-of-freedom release assembly is avoided. The other end of the tension sensor 20 is fixedly connected with a support rod and a connecting plate 21 thereof, and the support rods with different lengths are selected to adapt to different heights of the bottom of the optical-mechanical structure of the space optical telescope to be measured. The struts and their webs 21 are the final and output ends of the load-relieving force transfer path. The lifting connecting plate 22 is located at the other end of the support rod and the connecting plate 21 thereof and is fixedly connected with the support rod. The lifting connecting plate 22 adopts a plate-shell structure, reinforcing ribs are arranged in the lifting connecting plate to improve the rigidity of the lifting connecting plate, two sides of the lifting connecting plate 22 are fixedly connected with the movable pulley block assembly 27 respectively, as shown in fig. 6, the movable pulley block assembly 27 is used for realizing the free lifting of the components from '10' to '21' on the lifting connecting plate along the direction of the gravity vector, and therefore the purpose of releasing the degree of freedom of the other vertical direction is achieved. In addition, the lifting connecting plate 22 also realizes the transmission of unloading force through the movable pulley block assembly 27. The movable pulley block assembly 27 and the static pulley block assembly 28 are matched to realize multi-group winding of one steel wire rope, and offset load moment introduced by relative position errors between each movable pulley in the unloading force transmission path and the axes of the support rods and the connecting plates 21 of the movable pulleys is eliminated. In addition, the multiple groups of movable pulleys also have the functions of reducing the weight of the trim, and reducing the total volume and weight of the gravity unloading device. The stationary pulley block assembly 28 is attached to the uprights on either side of the gravity unloading assembly base 26 by bearing blocks. Two ends of a steel wire rope in the movable pulley block assembly 27 are fixedly connected with the balancing box 24 through the balancing box ball head connecting assembly 23. The balancing box ball head connecting assembly 23 can release the three-dimensional rotational freedom degree between the steel wire rope and the balancing box 24, so that the balancing box 24 is in a free state, and unbalanced moment caused by uneven friction force is eliminated. The unloading base reinforcing plate 25 is fixedly connected with the gravity unloading assembly base 26, so that the local strength of the gravity unloading assembly base 26 is reinforced, the rigidity of the whole unloading assembly is improved, and the unloading residual error caused by local deformation of the gravity unloading assembly base 26 is reduced. The gravity unloading assembly base 26 is fixedly connected with the flange surface on the bottom support plate of the base 8 through the flange surface of the bottom by using a plurality of groups of screws. The base 8 bottom support plate accomplishes the purpose of positioning the various gravity off-load components.

The working process of the invention is as follows:

1. the working principle of the invention is as follows:

after a specific mathematical model and a simulation algorithm are subjected to simulation analysis and loaded, the coordinates of a gravity balance point and the magnitude of the unloading force of a corresponding unloading point can be optimized according to the optical-mechanical configuration of a large-caliber optical load and the pose change residual error threshold of an optical assembly distributed by optical design. The results of the above analysis are input to the gravity unloading apparatus design.

Firstly, under the state of no gravity unloading, the large-caliber optical load realizes space positioning through a plurality of fixed supporting points. However, there is a slight elastic deformation inside the opto-mechanical system, typically on the order of microns to tens of microns, caused by gravity, and the internal stresses resulting therefrom. The deformation rebounds after the gravity of the track is released, so that the pose of each optical element in the light path with perfect ground mounting and calibration is changed, and the imaging quality of the system is damaged. For this purpose, a gravity unloading device was introduced during the set-up test.

First, a balancing force is applied according to the results of the computer simulation analysis. And connecting the output end of each independent gravity unloading device with a fixed tool, successively adding a balancing mass block into a balancing box, and measuring a balancing force introduced by the gravity of the balancing mass block by using a tension sensor until the internal tension of the steel wire rope displayed by the tension sensor is consistent with the simulation analysis result of the computer. At this time, a movable-static pulley block mechanism in the gravity unloading device is used. And fixedly connecting the output end of the adjusted gravity unloading device with an unloading point on the large-caliber optical load, and unlocking the movable-static pulley block mechanism. At this point, the trim mass position is released and there is a transient non-statically determinate process, as shown in FIG. 1. Due to the non-unloaded state, internal stress caused by gravity exists inside the optical-mechanical structure, and local elastic deformation related to the internal stress exists. And the loaded balance force is smaller than the resultant force of the support reaction force and the internal stress in the direction opposite to the gravity vector direction, so that the local micro-finite element of the optical-mechanical structure slightly moves in the direction opposite to the gravity vector. At the moment, the five-degree-of-freedom flexible joint of the gravity unloading device completely releases the degrees of freedom in the translational motion and three-dimensional rotation directions in a plane, and the movable-static pulley block mechanism releases the degrees of freedom in the gravity vector direction, so that the reverse motion cannot be interfered, and the direction and the size of micron-scale elastic deformation resilience caused by gravity are completely determined by the structural internal stress of the optical machine, thereby simulating the gravity releasing process.

When the micro deformation rebounds to elastic deformation and is eliminated, the internal stress of the interior of the optical-mechanical structure near the unloading point and introduced by gravity is close to zero. In this state, the balance force loaded by the gravity unloading device is equal to the gravity of the unloading point accessory, and the transient motion process is finished. Similarly, the gravity unloading points can be fixedly connected with the given positions on the optical mechanical structure assembly one by one, and elastic deformation of the areas near the unloading points caused by gravity can be released one by one. After all the balance forces for unloading are loaded, the local rigidity of the optical-mechanical structure is improved between local areas in the short span between unloading points, and elastic deformation caused by gravity can be resisted and eliminated. And local gravity is counteracted by the balancing mass near the unloading point, and the appearance characteristic of the optical machine structure after gravity release is simulated. And the optical components are adjusted in the above states, and the optical components are fixedly connected with the supporting structure after pose adjustment is completed, so that the state of the light path consistent with that under the condition of in-orbit microgravity can be obtained, and the image quality change caused by inconsistent 'sky-ground' mechanical environment is eliminated.

2. The principle of the device of the invention is as follows:

the output end fixedly connected with the space optical load unloading point is a spherical bearing, and the degree of freedom of the three-dimensional rotary motion is released through a ball joint. The plane thrust shaft system connected in series with the plane thrust shaft system can completely release the translational freedom degree in any direction in the plane. And the movable-fixed pulley assembly located on the gravity unloading assembly base and connected with the flexible joint in series completely releases the freedom degree along the gravity vector direction. The structure completely releases the spatial six-dimensional freedom degree of the unloading force, and mutual interference can be effectively avoided by adopting serial arrangement, so that free synthesis in the spatial motion vector direction is realized. The structure can eliminate the interference caused by over-constraint at the unloading point, and the loading direction of the unloading balance force is only determined by the releasing direction of the internal stress and is not influenced by the connection precision and the arrangement position precision of the device.

The arrangement mode can avoid that component force caused by the change of the direction of the loading force acts on the sensor to introduce loading balance force error. The movable-static pulley assembly is positioned at the final stage of the force transmission path, the gravity of the balancing mass block is converted into unloading force through a group of movable-static pulley assemblies with special configurations, the balancing force is reduced greatly, the size and the total weight of the gravity unloading device are reduced, and the requirements under special application environments such as vacuum containers are met.

The gravity unloading devices are fixedly connected to the bottom base, so that a stable supporting foundation is provided for the gravity unloading devices, and the positions among the unloading points and the relative variation quantity caused by the environment are ensured to be smaller than the limit stroke of the freedom degree releasing mechanism. The upper part of the unloading base is provided with a fixed connection support, and the fixed connection support is also provided with three fixed supporting points for space positioning of the large-caliber optical load. The fixed supporting point and the gravity unloading point jointly form a floating supporting system, namely the space position and the posture of the space optical load are determined, and the requirements for accurate adjustment and positioning of the optical axis of the optical load in the testing, assembling and adjusting processes are met. Meanwhile, a plurality of unloading points which only load balance force and do not restrict positioning are utilized to provide a mechanical environment for simulating the morphological characteristics of the optical machine structure after gravity release in the processes of installation, adjustment and testing. In addition, the device adopts a pure mechanical design, avoids the pollution problem caused by air leakage or liquid leakage in a gas or liquid static pressure system, and meets the requirements of special test environments such as vacuum, cold black and the like. And the size of the device is reduced through a special configuration, and the limitation of special application environments such as use in a just empty container on the size and weight of the device is met.

The above-described embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A floating support device for the ground gravity unloading of space optical loads is characterized by comprising a base (8), a plurality of groups of gravity unloading devices (6) arranged on the base (8), wherein the gravity unloading devices (6) are fixedly arranged below an optical load (7); the floating support device also comprises a plurality of groups of fixed support devices (9) arranged at the back of the optical load (7);

the gravity unloading device (6) comprises a gravity unloading component base (26), a vertical freedom degree release component, a force transmission mechanism, a tension sensor (20) and a five-freedom degree release component; the gravity unloading component base (26) is fixedly arranged on the base (8), one end of the vertical freedom degree releasing component is connected with the gravity unloading component base (26), and the other end of the vertical freedom degree releasing component is connected with the tension sensor (20) through a force transmission mechanism; one end of the five-freedom-degree release assembly is connected with a tension sensor (20), the other end of the five-freedom-degree release assembly is connected with an optical load (7), and the tension sensor (20) is used for measuring the pressure and the pulling force in the gravity unloading device (6).

2. The floating support device for the ground gravity unloading of the space optical load is characterized in that the five-degree-of-freedom release assembly comprises a ball bearing assembly and a thrust shafting assembly which are connected with the optical load (7), wherein one end of the ball bearing assembly is connected with the unloading connecting seat (10) in series, and the other end of the ball bearing assembly is connected with the thrust shafting assembly in series.

3. A floating support device for ground gravity unloading of space optical loads according to claim 2, characterized in that the ball bearing assembly comprises a ball bearing (11), a ball bearing housing (12), a ball bearing press plate (13), the ball bearing (11) being mounted in the ball bearing housing (12), the ball bearing press plate (13) providing a pre-stress.

4. The floating support device for the ground gravity unloading of the space optical load is characterized in that the thrust shafting assembly comprises a thrust ring (15), a steel ball (16), a retainer (17) and a thrust bearing seat (18), wherein the thrust ring (15) is fixedly connected with the ball bearing seat (12), and an annular gap is arranged between the retainer (17) and the thrust bearing seat (18).

5. The floating support device for the ground gravity unloading of the space optical load is characterized in that the vertical freedom degree releasing assembly comprises a lifting connecting plate (22) and a movable pulley block assembly (27), the lifting connecting plate (22) is fixedly arranged at the bottom end of the force transmission mechanism, and two sides of the lifting connecting plate (22) are respectively and fixedly connected with the movable pulley block assembly (27).

6. The floating support device for the ground gravity unloading of the space optical load is characterized in that the floating support device further comprises a static pulley block assembly, the static pulley block assembly is fixedly arranged on the upright posts at two sides of the gravity unloading assembly base (26) through static pulley bearing seats, and the movable pulley block assembly (27) and the static pulley block assembly (28) are matched to realize the multi-group winding of one steel wire rope.

7. The floating support device for the ground gravity unloading of the space optical load is characterized by further comprising a balancing box ball head connecting assembly (23) and a balancing box (24), wherein two ends of the steel wire rope in the movable pulley block assembly (27) are connected with the balancing box (24) in a ball hinge mode through the balancing box ball head connecting assembly (23), and the three-dimensional rotation freedom degree between the steel wire rope and the balancing box (24) can be released through the balancing box ball head connecting assembly (23).

8. A floating support device for ground gravity unloading of space optical loads according to claim 7, characterized in that the gravity unloading assembly base (26) is fixedly provided with a gravity unloading assembly base stiffening plate (25).

9. A floating support device for ground gravity unloading of space optical loads according to claim 1, characterized in that the gravity unloading devices (6) are of four groups and the fixed support devices (9) are of three groups.