Image motion compensation device in vacuum low-temperature environment based on Stewart mechanism

Abstract

The invention discloses an image motion compensation device in a vacuum low-temperature environment based on a Stewart mechanism, which relates to the field of optical system motion and comprises a movable platform, six single-leg driving rods and a bottom plate. The bottom of the movable platform and the six single-leg driving rods are fixed through thrust bearing assemblies respectively. The single-leg driving rod comprises a thrust bearing assembly, an upper hooke joint assembly, a ball screw, an angular contact ball bearing assembly, a high-precision servo motor assembly, a dust cover, a pre-tightening spring and a lower hooke joint assembly. The high-precision servo motor drives the ball screw to rotate, and the angular contact ball bearing is axially supported; the six single-leg driving rods are connected and fixed to the bottom plate through the six hooke joints in a threaded mode, and each hooke joint is composed of a cross-shaped rotating shaft, a ball bearing and a hooke joint supporting base. According to the invention, six-degree-of-freedom adjustment of the optical reflector in an on-orbit vacuum low-temperature environment is realized.

Description

Technical Field

[0001] The invention belongs to the field of optical system motion, and in particular relates to an image motion compensation device in a vacuum low-temperature environment based on a Stewart mechanism. Background Art

[0002] With the rapid advancement of optical technology, optical systems are being used more and more widely, the application environment is becoming more diverse, and the requirements for the imaging quality of the system are becoming higher and higher. The image quality movement caused by on-orbit temperature changes after installation and adjustment has become one of the main factors affecting the imaging quality of the system.

[0003] The existing Stewart parallel platform has the characteristics of high rigidity, strong bearing capacity, high posture accuracy, etc., and is widely used in aviation, aerospace and other industries. A large number of research results have been achieved in the theoretical research and practical application of parallel mechanisms, but they are basically limited to ground experiments and laboratory installation and adjustment, and cannot achieve real-time installation and adjustment under vacuum and low temperature conditions in the orbital environment. In view of this, according to the requirements of the accuracy, size, weight, activity space, application environment, etc. of this device, it is urgent to design an image motion compensation device in a vacuum and low temperature environment based on the Stewart mechanism. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an image motion compensation device in a vacuum and low-temperature environment based on the Stewart mechanism, which realizes the six-degree-of-freedom adjustment of the image quality movement of the optical mirror caused by temperature change on the track, so as to ensure the adjustment of the image quality movement of the optical mirror on the track and the self-locking of the servo motor when the power is off. The Hooke hinge bearing, angular contact ball bearing and thrust bearing greatly increase the load-bearing capacity of the image quality correction micro-displacement compensation device. The bearing can eliminate the structural gap and reduce the motor driving torque through the preload force. The structural parts are made of zero-expansion invar material, which greatly reduces the deformation caused by temperature change, better meets the adjustment of the optical mirror, and thus improves the high-resolution image imaging quality of the space optical system.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme:

[0006] An image motion compensation device in a vacuum and low-temperature environment based on a Stewart mechanism comprises a moving platform, six single-leg driving rods and a bottom plate; each of the single-leg driving rods comprises a thrust bearing assembly, an upper Hooke's hinge assembly and a lower Hooke's hinge assembly; the upper Hooke's hinge assembly and the thrust bearing assembly form a universal hinge; a groove is provided at the bottom of the moving platform for fixing the thrust bearing assemblies of the six universal hinges; the bottom of the moving platform and the six single-leg driving rods are fixed respectively by universal hinges; the six single-leg driving rods are connected and fixed to the bottom plate by screws of six lower Hooke's hinge assemblies.

[0007] Furthermore, one end of the thrust bearing assembly is fixed to the moving platform by means of screws, and the other end is fixed to the upper Hooke's hinge assembly by means of screws.

[0008] Furthermore, the single-leg drive rod also includes a ball screw adapter, a preload spring, a dust cover, a ball screw, an angular contact ball bearing assembly, and a high-precision servo motor assembly; one end of the ball screw adapter is fixed to the upper Hooke's hinge assembly, and the other end is fixed to the ball screw; the preload spring is compressed and clamped between the ball screw adapter and the dust cover; the mating section of the ball screw is clearance-fittedly connected with the angular contact ball bearing coupling; the angular contact ball bearing is connected to the high-precision servo motor, and the motor shaft and the coupling are matingly connected through the transmission section; the lower Hooke's hinge assembly is connected to the high-precision servo motor.

[0009] Furthermore, the rotation range of the thrust bearing assembly is 360°, and the rotation range of the upper Hooke's hinge assembly is ±30°.

[0010] Furthermore, the upper Hooke's hinge assembly includes a Hooke's hinge bearing seat, a cross shaft, a cross shaft end cover, a micro bearing and a bearing locking nut; the structure of the lower Hooke's hinge assembly is the same as that of the upper Hooke's hinge assembly.

[0011] Furthermore, the two axes of the cross shaft are orthogonal and have different lengths.

[0012] Furthermore, the thrust bearing, Hooke's bearing, ball screw and angular contact ball bearing of the thrust bearing assembly are all coated with a solid lubricating film.

[0013] Furthermore, the thrust bearing pressure ring and angular contact ball bearing pressure ring of the thrust bearing assembly are used in pairs. The pressure ring close to the angular contact ball bearing is used to tighten the bearing and adjust the bearing preload, and the pressure ring away from the angular contact ball bearing is used to tighten the first pressure ring to prevent loosening.

[0014] Furthermore, the thrust bearing assembly, upper Hooke's hinge assembly, ball screw adapter, angular contact ball bearing assembly, high-precision servo motor assembly and the rotating shaft and mounting structure of the lower Hooke's hinge assembly are all made of zero-expansion Invar material to ensure that the deformation of the mechanism is reduced under temperature changes, thereby ensuring the accuracy of the mechanism.

[0015] Furthermore, the image motion compensation device has six degrees of freedom adjustment capability in a vacuum and low-temperature environment.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The structure is relatively simple and compact;

[0018] 2. The two orthogonal axes of the cross shaft of the Hooke hinge are of different lengths, which gives the Hooke hinge more room for movement, increases the rotation angle and makes the structure more compact, making it easier to install and adjust. The high-precision bearings at both ends of the cross shaft have high stiffness and low friction torque. The universal hinge replaces the ball bearing, reduces the gap between the structures through the bearing preload, and improves the adjustment accuracy.

[0019] 3. In order to solve the sealing and condensation problems of grease lubrication in vacuum and low-temperature environments, the thrust bearings, Hook hinge bearings, ball screws and angular contact ball bearings of the present invention are all plated with solid lubricating films. The solid lubricating film can still maintain good lubrication performance under vacuum and low-temperature conditions, and will not cause condensation and sealing problems of grease lubrication, thereby ensuring the reliability and stability of the device's on-track operation. Solid lubrication is used to solve the lubrication problem, and precision bearings are used in the movable joints. The bearings are all solid lubricated, which reduces the assembly clearance of each joint, improves the adjustment accuracy of the device, simplifies the sealing structure required for traditional oil-lubricated bearings, and solves the problem of grease lubrication condensation in low-temperature environments on-track.

[0020] 4. High overall rigidity. The six-bar parallel structure and precision bearing support make the present invention have high rigidity. Through the reasonable design of the construction quantity and kinematic pairs, the present invention has the ability to adjust six degrees of freedom. This multi-degree-of-freedom adjustment function enables the device to accurately adjust the position and posture of the optical mirror, meeting the requirements for high-precision adjustment of the optical system in the on-orbit environment, thereby improving the high-resolution image quality of the space optical system.

[0021] 5. Strong temperature adaptability. The whole structure adopts zero expansion invar material to minimize the deformation of parts caused by temperature changes, reduce the structural gap changes caused by part deformation, and reduce the problem of reduced device accuracy. The present invention is used to correct the image quality movement of optical components caused by temperature changes in an ultra-low temperature environment on orbit, thereby improving the high-resolution image quality of space optical systems.

[0022] 6. The groove design of the moving platform ensures a compact layout: There are 6 grooves at the bottom of the moving platform, which are used to fix the thrust bearings. This groove design not only ensures the adjustment space of the mechanism, but also makes the device layout more compact, which is conducive to reducing the volume and weight of the device and improving its applicability in limited space.

[0023] 7. The single-leg drive rod structure is easy to install and maintain: The single-leg drive rod has a reasonable structural design, including ball screws, angular contact ball bearings, high-precision servo motors, dust covers, preload springs and other components. The connection between the components is fixed by screws, which is convenient for installation, disassembly and maintenance. For example, one end of the ball screw adapter is fixed to the upper Hook hinge assembly by screws, and the other end is fixed to the ball screw by screws. This design makes it easy to operate when the ball screw needs to be maintained or replaced, which improves the maintainability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of an image motion compensation device based on the Stewart mechanism in a vacuum low-temperature environment of the present invention.

[0025] Figure 2 It is a top view schematic diagram of the moving platform of the present invention.

[0026] Figure 3 It is a cross-sectional schematic diagram of a single-leg driving rod of the present invention.

[0027] Figure 4 It is a schematic diagram of a thrust bearing assembly of the present invention.

[0028] Figure 5 It is a schematic diagram of the thrust bearing adapter shaft of the present invention.

[0029] Figure 6 It is a schematic diagram of a thrust bearing seat of the present invention.

[0030] Figure 7 It is a schematic diagram of the thrust bearing pressure ring of the present invention.

[0031] Figure 8 It is a schematic diagram of a Hooke's hinge assembly of the present invention.

[0032] Fig. 9 It is a schematic diagram of a Hooke's hinge seat of the present invention.

[0033] Fig.10 It is a schematic diagram of a cross shaft of the present invention.

[0034] Fig.11 It is a schematic diagram of a micro bearing pressure ring of the present invention.

[0035] Fig.12 It is a schematic diagram of a ball screw of the present invention.

[0036] Fig.13 It is a schematic diagram of the ball screw nut of the present invention.

[0037] Fig.14 It is a schematic diagram of the ball screw of the present invention.

[0038] Fig.15 It is a schematic diagram of an angular contact ball bearing assembly of the present invention.

[0039] Fig.16 It is a schematic diagram of a coupling of the present invention.

[0040] Fig.17 It is a schematic diagram of a bearing pressing ring of the present invention.

[0041] Fig.18 It is a schematic diagram of a high-precision servo motor assembly of the present invention.

[0042] Fig.19 It is a schematic diagram of a base plate of the present invention.

[0043] The accompanying drawings are marked as follows: image motion compensation device under vacuum and low temperature environment based on Stewart mechanism 1, moving platform 2, thrust bearing assembly 3, upper Hooke's hinge assembly 4, ball screw adapter 5, preload spring 6, dust cover 7, ball screw 8, angular contact ball bearing assembly 9, high-precision servo motor assembly 10, lower Hooke's hinge assembly 11, bottom plate 12, thrust bearing adapter shaft 301, seventh thread segment 3011, first overtravel groove 3012, The third threaded hole 3013, the bearing inner ring contact surface 3014, the thrust bearing end cover 302, the thrust bearing seat 303, the first threaded hole 3031, the first chamfer 3032, the second overrun groove 3033, the bearing outer ring contact surface 3034, the thrust bearing pressure ring 304, the sixth threaded section 3041, the third notch 3042, the thrust bearing 305, the Hook hinge bearing seat 401, the fifth threaded section 4011, the second chamfer 4012, the countersunk screw Threaded hole 4013, cross shaft 402, bearing mounting section 4021, second threaded hole 4022, cross shaft end cover 403, micro bearing 404, bearing locking nut 405, fourth threaded section 4051, first notch 4052, ball screw nut 801, third threaded section 8011, countersunk mounting hole 8012, ball screw 802, first threaded section 8021, first mating section 8022, angular contact ball bearing coupling Device 901, second matching section 9011, second thread section 9012, bearing assembly section 9013, third overtravel groove 9014, D-shaped groove 9015, bearing pressure ring 902, eighth thread section 9021, second notch 9022, angular contact ball bearing end cover 903, angular contact ball bearing 904, bearing seat 905, high-precision servo motor 1001, motor mounting seat 1002, motor baffle 1003, servo motor base plate 1004. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] like Figure 1-Figure 19 As shown, an image motion compensation device 1 in a vacuum low-temperature environment based on a Stewart mechanism according to an embodiment of the present invention comprises a moving platform 2, six single-leg driving rods and a base plate 12.

[0046] The bottom of the moving platform 2 is provided with a groove for fixing 6 universal hinges. The bottom of the moving platform 2 and the 6 single-leg driving rods are fixed by universal hinges respectively. The universal hinge is composed of an upper Hooke's hinge assembly 4 and a thrust bearing assembly 3. The 6 single-leg driving rods are fixed to the bottom plate 12 by screw connection through 6 lower Hooke's hinge assemblies 11. The upper Hooke's hinge assembly 4 is composed of a cross shaft 402, a micro bearing 404 and a Hooke's hinge bearing seat 401. The structure of the lower Hooke's hinge assembly 11 is the same as that of the upper Hooke's hinge assembly 4.

[0047] Specifically, Figure 2 As shown, the bottom of the moving platform 2 is provided with 6 grooves, which are respectively used to fix the thrust bearing assembly 3. The design of the grooves can not only ensure the adjustment space of the mechanism, but also make the layout of the device more compact.

[0048] Specifically, each of the single-leg driving rods includes a thrust bearing assembly 3, an upper Hooke's hinge assembly 4, a ball screw adapter 5, a preload spring 6, a dust cover 7, a ball screw 8, an angular contact ball bearing assembly 9, a high-precision servo motor assembly 10, and a lower Hooke's hinge assembly 11. One end of the thrust bearing assembly 3 is fixed to the moving platform 2 by screws, and the other end is fixed to the upper Hooke's hinge assembly 4 by screws to form a universal hinge; one end of the ball screw adapter 5 is fixed to the upper Hooke's hinge assembly 4 by screws, and the other end is fixed to the ball screw 8 by screws; the preload spring 6 is compressed and clamped between the ball screw adapter 5 and the dust cover 7; the matching section of the ball screw 8 is matched and connected with the coupling of the angular contact ball bearing 9; the angular contact ball bearing 9 is fixed to the high-precision servo motor assembly 10 by screws, and the motor shaft is matched and connected with the coupling through the transmission section; the lower Hooke's hinge assembly 11 is fixed to the high-precision servo motor assembly 10 by screws.

[0049] Specifically, Fig.12 , Fig.15As shown, the ball screw 8 includes a ball screw nut 801 and a ball screw rod 802. The ball screw nut 801 is connected to the ball screw adapter 5 by screws. One end of the ball screw rod 802 is threadedly connected to the ball screw nut 801, and the other end is assembled with a clearance fit with the angular contact ball bearing coupling 901. One end of the dust cover 7 contacts the angular contact ball bearing end cover 903, and the other end is compressed and pre-tightened by the pre-tightening spring 6. The angular contact ball bearing coupling 901 is connected to the high-precision servo motor 1001 by a D-shaped groove, and the lower Hooke hinge assembly 11 is connected to the servo motor base plate 1004 by screws.

[0050] Specifically, Figure 4 As shown, the thrust bearing assembly 3 includes a thrust bearing adapter shaft 301, a thrust bearing end cover 302, a thrust bearing seat 303, a thrust bearing pressure ring 304 and a thrust bearing 305. The thrust bearing 305 is installed in the thrust bearing seat 303, and the thrust bearing 305 and the thrust bearing seat 303 are assembled by clearance fit, the outer ring of the bearing is pressed by the thrust bearing end cover 302, and the thrust bearing end cover 302 and the thrust bearing seat 303 are fixed by screws; the thrust bearing 305 and the thrust bearing adapter shaft 301 are assembled by clearance fit, and the inner ring is threadedly fixed to the adapter shaft by the thrust bearing pressure ring 304; the thrust bearing assembly 3 is of ultra-precision grade, adopts solid lubrication, and has a rotation range of 360°. The thrust bearing adapter shaft 301 penetrates the inner ring of the bearing and is thread-locked by the thrust bearing pressure ring 304. The thrust bearing adapter shaft 301 and the thrust bearing seat 303 are respectively provided with a first overrun groove 3012 and a second overrun groove 3033, which are convenient for machining and backing out and ensure the flatness of the bearing contact surface.

[0051] Specifically, Figure 5 As shown, the thrust bearing adapter shaft 301 is made of zero expansion invar steel to ensure that the shrinkage of the part itself is 0 under temperature changes, and the thrust bearing adapter shaft 301 is provided with a seventh thread segment 3011, a first overtravel groove 3012 and a third threaded hole 3013. The seventh thread segment 3011 is threadedly fixed to the thrust bearing pressure ring 304, the first overtravel groove 3012 facilitates machining and backing out and ensures the flatness of the contact surface 3014 with the bearing inner ring, and the upper Hooke hinge assembly 4 is screwed to the thrust bearing adapter shaft 301 through the third threaded hole 3013.

[0052] Specifically, Figure 6 As shown, the thrust bearing seat 303 is made of zero expansion invar to ensure that the shrinkage of the part itself is 0 under temperature changes, and the thrust bearing seat 303 is provided with a first threaded hole 3031, a first chamfer 3032 and a second overrun groove 3033. The first threaded hole 3031 is used for screw connection with the thrust bearing end cover 302, the first chamfer 3032 facilitates the installation of the thrust bearing 305, and the second overrun groove 3033 facilitates machining and backing out and ensures the flatness of the contact surface 3034 with the bearing outer ring.

[0053] Specifically, Figure 7 As shown, the thrust bearing pressing ring 304 is made of zero expansion invar steel to ensure that the shrinkage of the part itself is 0 under temperature changes, to prevent the preload force of the thrust bearing from decreasing and the precision from deteriorating. The number of thrust bearing pressing rings 304 is 2, the pressing ring close to the thrust bearing 305 is used to press the thrust bearing 305, and the pressing ring far from the thrust bearing 305 is used to press the first pressing ring to prevent loosening. The thrust bearing pressing ring 304 is provided with a sixth thread segment 3041 and a third notch 3042. The sixth thread segment 3041 is used to be threadedly connected with the thrust bearing adapter shaft 301, to press the inner ring of the thrust bearing 305, and the third notch 3042 is convenient for the locking tooling operation to lock the thrust bearing pressing ring 304.

[0054] Specifically, Figure 8 As shown, the upper Hooke hinge assembly 4 includes 4 Hooke hinge bearing seats 401, 1 cross shaft 402, 4 cross shaft end covers 403, 4 micro bearings 404 and 4 bearing locking nuts 405. The micro bearing 404 adopts solid lubrication, and the micro bearing 404 is installed in the Hooke hinge bearing seat 401, and the outer ring is assembled with the Hooke hinge bearing seat 401 with clearance, and the outer ring of the bearing is pressed with the bearing locking nut 405, and the cross shaft 402 is inserted into the inner ring of the bearing, and the inner ring of the bearing and the cross shaft 402 are pressed with the cross shaft end cover 403 on the end face. The outer ring of the bearing is threadedly fixed with the Hooke hinge bearing seat 401 through the bearing locking nut 405; the cross shaft 402 is assembled with the inner ring of the micro bearing 404 with clearance, and the two ends of the cross shaft 402 are fixed with screws through the cross shaft end cover 403.

[0055] The two orthogonal axes of the cross shaft 402 have different lengths, which can increase the adjustment space of the Hook joint and make the structure more compact. The upper Hook joint assembly 4 can realize 60° rotation in two directions. The universal hinge composed of the thrust bearing assembly 3 and the upper Hook joint assembly 4 can realize the three-axis rotation of the moving platform X, Y, and Z.

[0056] Specifically, Fig. 9 As shown, the Hooke hinge bearing seat 401 is made of zero expansion invar steel to ensure that the shrinkage of the part itself is 0 under temperature changes. The Hooke hinge bearing seat 401 is provided with a fifth thread segment 4011, a second chamfer 4012 and a countersunk hole 4013. The fifth thread segment 4011 is used for threaded connection with the bearing locking nut 405, the second chamfer 4012 facilitates the installation of the micro bearing 404, and the countersunk hole 4013 is used for connecting with the structural screws at both ends of the upper Hooke hinge assembly 4. The countersunk hole can save the installation space of the screw head and make the structure more compact.

[0057] Specifically, Fig.10As shown, the cross shaft 402 is made of zero expansion invar to ensure that the shrinkage of the part itself is 0 under temperature changes. The cross shaft 402 is provided with a bearing mounting section 4021 and a second threaded hole 4022. The bearing mounting section 4021 is used for tight fit assembly with the inner ring of the micro bearing 404, and the second threaded hole 4022 is used for screw connection with the cross shaft end cover 403. The two orthogonal axes of the cross shaft 402 are of different lengths, which increases the rotation range of the Hooke's hinge while reducing the structural volume.

[0058] Specifically, Fig.11 As shown, the bearing locking nut 405 is provided with a fourth thread segment 4051 and a first notch 4052. The fourth thread segment 4051 is used for threaded connection with the Hook hinge bearing seat 401, and the first notch 4052 is convenient for the locking tooling operation to lock the bearing locking nut 405.

[0059] Specifically, Fig.12 As shown, the ball screw 8 includes a ball screw nut 801 and a ball screw rod 802. The ball screw nut 801 and the ball screw rod 802 are connected by threads. When working, the rotation direction of the ball screw nut 801 is fixed, and the ball screw rod 802 rotates, and the rotation of the ball screw rod 802 is converted into the translation of the ball screw nut 801 through the thread conduction.

[0060] Specifically, Fig.13 As shown, the ball screw nut 801 is provided with a third thread segment 8011 and a countersunk mounting hole 8012. The third thread segment 8011 is plated with a solid lubricating film and is used for threaded connection with the ball screw rod 802, and the countersunk mounting hole 8012 is used for screw connection with the ball screw adapter 5, and the screw head is sunk in the air, which can save structural space.

[0061] Specifically, Fig.14 As shown, the ball screw 802 is provided with a first thread segment 8021 and a first matching segment 8022. The first thread segment 8021 is plated with a solid lubricating film and is used for threaded connection with the ball screw nut 801, and the first matching segment 8022 is used for clearance matching connection with the angular contact ball bearing 9.

[0062] Specifically, Fig.15 As shown, the angular contact ball bearing 9 comprises an angular contact ball bearing coupling 901, a bearing pressure ring 902, an angular contact ball bearing end cover 903, an angular contact ball bearing 904 and a bearing seat 905. The inner ring of the angular contact ball bearing 904 is tightly fitted and connected to the angular contact ball bearing coupling 901, the outer ring of the angular contact ball bearing 904 is tightly fitted and connected to the bearing seat 905, the angular contact ball bearing end cover 903 is connected to the bearing seat 905 by screws, and the bearing pressure ring 902 is fixedly connected to the angular contact ball bearing coupling 901 by threads and pressed against the inner ring of the angular contact ball bearing 904.

[0063] Specifically, Fig.16 As shown, the angular contact ball bearing coupling 901 is made of zero expansion invar steel to ensure that the shrinkage of the parts themselves is 0 under temperature changes. The angular contact ball bearing coupling 901 is provided with a second matching section 9011, a second threaded section 9012, a bearing assembly section 9013, a third overtravel groove 9014 and a D-shaped groove 9015. The second matching section 9011 is used for clearance matching with the ball screw 8, the second threaded section 9012 is used for threaded connection with the bearing pressure ring 902, the bearing assembly section 9013 is used for tight matching with the angular contact ball bearing 904, the third overtravel groove 9014 is convenient for machining and backing out and ensures the flatness of the contact surface with the outer ring of the bearing, and the D-shaped groove 9015 is used for matching with the motor shaft to prevent the motor shaft and the angular contact ball bearing coupling 901 from rotating relative to each other.

[0064] Specifically, Fig.17 As shown, the bearing pressing ring 902 is made of zero expansion invar steel to ensure that the shrinkage of the part itself is 0 under temperature changes, to prevent the preload force of the thrust bearing from decreasing and the precision from deteriorating. The number of bearing pressing rings 902 is 2, the pressing ring close to the angular contact ball bearing 904 is used to press the angular contact ball bearing 904, and the pressing ring away from the angular contact ball bearing 904 is used to press the first pressing ring to prevent loosening. The bearing pressing ring 902 is provided with an eighth thread segment 9021 and a second notch 9022. The eighth thread segment 9021 is used to be threadedly connected with the angular contact ball bearing coupling 901, to press the inner ring of the angular contact ball bearing 904, and the second notch 9022 facilitates the operation of the locking tooling to lock the bearing pressing ring 902.

[0065] Specifically, Fig.18 As shown, the high-precision servo motor assembly 10 includes a high-precision servo motor 1001, a motor mounting seat 1002, a motor baffle 1003 and a servo motor bottom plate 1004. The high-precision servo motor 1001 can be used in a vacuum low-temperature environment, and the motor mounting seat 1002, the motor baffle 1003 and the servo motor bottom plate 1004 are all made of zero-expansion invar steel to ensure that the structural shrinkage under temperature changes is 0. The high-precision servo motor 1001 is connected to the motor connection seat 1002 by screws, the motor connection seat 1002 is connected to the motor baffle 1003 by screws, and the servo motor bottom plate 1004 is connected to the motor connection seat 1002 by screws. The screws are all countersunk screws, which can save screw head space.

[0066] Specifically, Fig.19 As shown, the bottom plate 12 is located at the bottom of the mechanism, with a diameter slightly larger than the moving platform 2, and 6 grooves are provided on the upper surface, which are respectively used to fix 6 lower Hooke's hinge assemblies 11. The design of the grooves can not only ensure the adjustment space of the mechanism, but also make the device layout more compact.

[0067] The degree of freedom calculation process of the image quality correction micro-displacement compensation device of the present invention is as follows: there are 14 components in total, including 1 moving platform and 1 bottom plate, each single-leg driving rod is regarded as 2 components (separated from the ball screw, the upper part of the ball screw is connected to the universal joint and the moving platform, and the lower part of the ball screw is connected to the lower Hooke's hinge assembly and the bottom plate), then 6 single-leg driving rods have a total of 12 components; there are 18 kinematic pairs, of which 6 are universal joints (composed of a thrust bearing assembly 3 and an upper Hooke's hinge assembly 4), 6 are single-degree-of-freedom moving pairs (ball screws 8), and 6 are two-degree-of-freedom Hooke's hinges (lower Hooke's hinge assembly 11). The total degree of freedom f=6×(14-1)-6×(6-3)-6×(6-1)-6×(6-2)=6 is calculated, that is, the image displacement compensation device has the ability to adjust six degrees of freedom in a vacuum and low-temperature environment.

Claims

1. An image motion compensation device based on a Stewart mechanism in a vacuum and low temperature environment, characterized in that: It includes a moving platform, 6 single-leg driving rods and a base plate; each of the single-leg driving rods includes a thrust bearing assembly, an upper Hooke's hinge assembly and a lower Hooke's hinge assembly; the upper Hooke's hinge assembly and the thrust bearing assembly form a universal hinge; a groove is provided at the bottom of the moving platform for fixing the thrust bearing assemblies of the 6 universal hinges; the bottom of the moving platform and the 6 single-leg driving rods are fixed respectively by universal hinges; the 6 single-leg driving rods are connected and fixed to the base plate by 6 lower Hooke's hinge assembly screws.

2. The image motion compensation device based on the Stewart mechanism in a vacuum and low temperature environment according to claim 1, characterized in that: One end of the thrust bearing assembly is fixed to the moving platform by screws, and the other end is fixed to the upper Hooke hinge assembly by screws.

3. The image motion compensation device based on the Stewart mechanism in a vacuum and low temperature environment according to claim 1, characterized in that: The single-leg driving rod also includes a ball screw adapter, a preload spring, a dust cover, a ball screw, an angular contact ball bearing assembly, and a high-precision servo motor assembly; one end of the ball screw adapter is fixed to the upper Hooke's hinge assembly, and the other end is fixed to the ball screw; the preload spring is compressed and clamped between the ball screw adapter and the dust cover; the mating section of the ball screw is clearance-fittedly connected with the angular contact ball bearing coupling; the angular contact ball bearing assembly is connected to the high-precision servo motor assembly, and the motor shaft and the coupling are matingly connected through the transmission section; the lower Hooke's hinge assembly is connected to the high-precision servo motor assembly.

4. The image motion compensation device based on the Stewart mechanism in a vacuum and low temperature environment according to claim 1, characterized in that: The rotation range of the thrust bearing assembly is 360°, and the rotation range of the upper Hooke's hinge assembly is ±30°.

5. The image motion compensation device based on the Stewart mechanism in a vacuum and low temperature environment according to claim 1, characterized in that: The upper Hooke's hinge assembly comprises a Hooke's hinge bearing seat, a cross shaft, a cross shaft end cover, a micro bearing and a bearing locking nut; the structure of the lower Hooke's hinge assembly is the same as that of the upper Hooke's hinge assembly.

6. The image motion compensation device based on the Stewart mechanism in a vacuum and low temperature environment according to claim 5, characterized in that: The two axes of the cross shaft are orthogonal and of unequal lengths.

7. The image motion compensation device based on the Stewart mechanism in a vacuum and low temperature environment according to claim 2 or 4, characterized in that: The thrust bearing, the Hooke hinge bearing, the ball screw and the angular contact ball bearing of the thrust bearing assembly are all plated with a solid lubricating film.

8. The image motion compensation device based on the Stewart mechanism in a vacuum and low temperature environment according to claim 2 or 4, characterized in that: The thrust bearing pressure ring and the angular contact ball bearing pressure ring of the thrust bearing assembly are used in pairs. The pressure ring close to the angular contact ball bearing is used to press the bearing and adjust the bearing preload, and the pressure ring away from the angular contact ball bearing is used to press the first pressure ring to prevent loosening.

9. The image motion compensation device based on the Stewart mechanism in a vacuum and low temperature environment according to claim 2, characterized in that: The thrust bearing assembly, upper Hooke's hinge assembly, ball screw adapter, angular contact ball bearing assembly, high-precision servo motor assembly and the rotating shaft and mounting structure of the lower Hooke's hinge assembly are all made of zero-expansion Invar material to ensure that the deformation of the mechanism is reduced under temperature changes, thereby ensuring the accuracy of the mechanism.

10. The image motion compensation device based on the Stewart mechanism in a vacuum and low temperature environment according to claim 1, characterized in that: The image motion compensation device has six degrees of freedom adjustment capability in a vacuum and low-temperature environment.

Images