Suspension type microgravity ground test system

Abstract

The invention discloses a suspension type microgravity ground test system, relates to the technical field of mechanical design, and solves the problems that a suspension type microgravity ground simulation system is poor in bearing capacity and large in friction resistance of a transmission mechanism, and interference is caused by inclination of a sling. Comprising a main supporting frame, an X-axis translation assembly, a Y-axis translation assembly, a Z-axis suspension assembly, a three-axis rotating assembly and a carrying platform, the X-axis translation assembly is used for achieving displacement of the Y-axis translation assembly on the main supporting frame in the X-axis direction, and the Y-axis translation assembly is used for achieving displacement of the carrying platform on the main supporting frame in the Y-axis direction; the Z-axis suspension assembly is used for achieving displacement of the three-axis rotating assembly and the test prototype in the Z-axis direction, the test prototype is suspended below the three-axis rotating assembly and used for simulating a suspension type microgravity ground test of the test prototype, and the gravity compensation precision is improved, and the simulation precision of translation and rotation in the microgravity environment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical design, and in particular to a suspended microgravity ground test system. Background Art

[0002] Microgravity environment simulation technology, a crucial pillar of aerospace engineering verification systems, has become a key indicator of a nation's aerospace technology strength, coinciding with the rapid development of manned spaceflight, deep space exploration, and space station construction. The current international aerospace sector is trending towards high frequency, low cost, and modularization, placing ever-more stringent demands on the on-orbit reliability of spacecraft. Given the enormous cost of on-orbit testing and the difficulty of post-launch commissioning and maintenance, a high-fidelity ground-based microgravity simulation system is required to simulate the space environment before launch to ensure that various spacecraft equipment meet the required performance specifications during on-orbit operation. Currently, ground-based microgravity simulation has become the most efficient and cost-effective technology for verifying spacecraft performance, attracting widespread attention from around the world.

[0003] Based on physical principles, ground-based microgravity simulation technologies can be categorized as drop tower, water flotation, air flotation, and suspension methods. The drop tower method utilizes a 100-meter vacuum microgravity tower to create a microgravity environment through free fall. This method offers the advantage of high-precision simulations with six degrees of freedom in three dimensions. However, it is expensive, space is limited within the tower, and test times are limited to seconds, making it incapable of fully testing prototype performance. The water flotation method, which relies on the principle of neutral buoyancy to simulate microgravity, offers the advantage of unlimited time-limited three-dimensional simulations. However, fluid disturbances limit simulation accuracy, and waterproofing the tested prototypes increases cost and complexity. The air flotation method uses gas bearings to form an air film to support the simulation prototype and offset the effects of gravity. This method offers high precision, ease of maintenance, and no time limit, but it is limited to two-dimensional translational microgravity simulations. The suspension method uses a gravity compensation mechanism to offset the prototype's gravity, achieving three-dimensional microgravity simulations. Its technical advantages lie in its simple structure, strong scalability, unlimited test cycles, ease of maintenance, and manageable costs. Therefore, it is widely used in many countries.

[0004] Although the suspension method has become the mainstream technical route due to its unique advantages, it still faces considerable technical difficulties in engineering practice. First, the traditional truss mechanism is prone to elastic deformation when bearing loads, resulting in deviations in vertical motion displacement. Second, the coupling of Coulomb friction and viscous friction in the pulley transmission system can cause fluctuations in the compensation force, which seriously affects the accuracy of microgravity simulation. In addition, during multi-degree-of-freedom movement, the external forces and interference generated by the tilting and flexible shaking of the sling will also reduce the effect of gravity compensation. Summary of the Invention

[0005] In view of the problems of poor load-bearing capacity, large friction resistance of the transmission mechanism and interference caused by the inclination of the suspension cable in the above-mentioned suspended microgravity ground simulation system, the purpose of the present invention is to provide an innovative suspended microgravity simulation system design. By integrating a high-load-bearing structural truss and a low-friction sliding device universal ball head structure design, it aims to solve the problems of low precision and poor reliability of the traditional suspension method at a low cost. At the same time, a high-precision visual servo tracking control method based on deep reinforcement learning is adopted to reduce the inclination angle of the suspension cable, improve the real-time compensation accuracy, ensure high fidelity during high-speed maneuver simulation, and provide an innovative technology platform for ground verification of the new generation of aerospace equipment.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: A suspended microgravity ground test system, comprising: a main support frame, an X-axis translation assembly, a Y-axis translation assembly, a Z-axis suspension assembly, a three-axis rotation assembly, and a loading platform; the main support frame is a cubic structure frame; the X-axis translation assembly is mounted on the top of the main support frame; the Y-axis translation assembly is mounted on the X-axis translation assembly; the loading platform is mounted on the Y-axis translation assembly; the Z-axis suspension assembly is mounted within the loading platform; and the test prototype is suspended from the Z-axis suspension assembly via the three-axis rotation assembly; The main support frame is used to support the X-axis translation assembly, Y-axis translation assembly, Z-axis suspension assembly, loading platform and test prototype. The X-axis translation assembly is used to realize the displacement of the Y-axis translation assembly on the main support frame along the X-axis direction. The Y-axis translation assembly is used to realize the displacement of the loading platform on the main support frame along the Y-axis direction. The Z-axis suspension assembly is used to realize the displacement of the three-axis rotation assembly and the test prototype along the Z-axis direction. The test prototype is suspended below the three-axis rotation assembly to simulate the suspended microgravity ground test of the test prototype.

[0007] The above-mentioned suspended microgravity ground test system, wherein the main support frame includes: an upper frame 13, a base frame 16, a column structure 17 and a reinforcement beam 19. The upper frame 13 and the base frame 16 are both planar rectangular frame structures. Each corner of the upper frame 13 is connected to each corner of the base frame 16 by a column structure 17. The four column structures 17 are all vertically arranged and have the same length; a reinforcement beam 19 is connected between any two connected profiles on the upper frame 13, and a reinforcement beam 19 is connected between any two connected profiles on the base frame 16; the two profiles at any corner of the upper frame 13 are respectively connected to the column structure 17 at the corner position by a reinforcement beam 19; the two profiles at any corner of the base frame 16 are respectively connected to the column structure 17 at the corner position by a reinforcement beam 19.

[0008] The above-mentioned suspended microgravity ground test system, wherein the X-axis translation assembly includes: a polished rod 21, a vertical bearing seat 22, a first synchronous pulley 23, a first synchronous belt 24, a first linear slide 25, a tray device 46 and a load-bearing crossbeam 43. A polished rod 21 is respectively provided on the left and right profiles of the upper frame 13. The two polished rods 21 are rotatably mounted on the profile of the upper frame 13 through five vertical bearing seats 22. The two polished rods 21 are parallel to each other, and a synchronous pulley 23 is respectively installed at both ends of each polished rod 21. The two synchronous pulleys 23 on the front side are connected to the upper frame 13. The upper frame 13 is connected to the upper frame 13 through a synchronous belt 24 for transmission, and the two synchronous pulleys 23 on the rear side are connected to the upper frame 13 through another synchronous belt 24 for transmission. A tray device 46 is respectively provided on the front profile and the rear profile of the upper frame 13. Each tray device 46 is slidably installed on the profile of the upper frame 13 through a first linear slide rail 25. The tray device 46 on the front side is connected to the synchronous belt 24 on the front side, and the tray device 46 on the rear side is connected to the synchronous belt 24 on the rear side. The two tray devices 46 are symmetrically arranged on the left and right, and the two ends of the load-bearing beam 43 are respectively connected to the two tray devices 46.

[0009] The above-mentioned suspended microgravity ground test system, wherein the X-axis translation assembly also includes: a square frame 31, a second synchronous pulley 32, a second synchronous belt 33, an X-axis motor 34 and a base 35. The square frame 31 is installed on the left or right side of the upper frame 13, and the base 35 is installed at the bottom of the square frame 31. The X-axis motor 34 is installed on the base 35. A second synchronous pulley 32 is installed at the output end of the X-axis motor 34, and another second synchronous pulley 32 is installed on the light rod 21 on the same side of the square frame 31. The two second synchronous pulleys 32 are connected by a second synchronous belt 33. The X-axis motor 34 is used to drive the light rod 21 to rotate and thereby drive the load-bearing beam 43 to move along the X-axis direction.

[0010] The above-mentioned suspended microgravity ground test system, wherein the Y-axis translation assembly includes: a Y-axis motor 41, a third synchronous pulley 42, a third synchronous belt 44, a loading platform 45, an idler wheel 52 and a second linear slide 53. The loading platform 45 is slidably mounted on the load-bearing beam 43 through the second linear slide 53. The Y-axis motor 41 is mounted on a tray device 46. The third synchronous pulley 42 is mounted on the output end of the Y-axis motor 41. The idler wheel 52 is rotatably mounted on another tray device 46. The third synchronous pulley 42 and the idler wheel 52 are connected by the third synchronous belt 44. The loading platform 45 is connected to the third synchronous belt 44. The Y-axis motor 41 is used to drive the loading platform 45 to move along the Y-axis direction.

[0011] The above-mentioned suspended microgravity ground test system, in which the load platform 45 also includes: stainless steel studs 61, an upper part 62 of the load platform and a lower part 63 of the load platform. The upper part 62 of the load platform and the lower part 63 of the load platform are respectively arranged on the upper and lower sides of the load-bearing beam 43. The upper part 62 of the load platform and the lower part 63 of the load platform are connected by multiple stainless steel studs 61. The lower surface of the upper part 62 of the load platform and the upper surface of the load-bearing beam 43 are slidably connected by a second linear slide rail 53. The lateral end face of the upper part 62 of the load platform is connected to the third synchronous belt 44. The Z-axis suspension assembly is installed in the lower part 63 of the load platform.

[0012] In the above-mentioned suspended microgravity ground test system, the carrier platform 45 also includes: a binocular camera, which is installed on the lower surface of the lower part 63 of the carrier platform. The binocular camera is used to measure the distance error between the test prototype and the carrier platform, and feed the error back to the deep reinforcement learning network to obtain a motor control compensation signal to ensure the tracking accuracy of the carrier platform to the simulated spacecraft.

[0013] The above-mentioned suspended microgravity ground test system, wherein the Z-axis suspension assembly includes: a pulley group 64 and a counterweight, the pulley group 64 includes: a V-type pulley and a suspension rope, the lower part 63 of the loading platform includes: a top plate, a bottom plate and a connecting beam, the top plate and the bottom plate are both arranged horizontally, the lower surface of the top plate and the upper surface of the bottom plate are connected by multiple connecting beams, at least two rotatable V-type pulleys are installed on the lower surface of the top plate, and at least one rotatable V-type pulley is installed on the upper surface of the bottom plate, and the multiple V-type pulleys are located in the same vertical plane, the number of V-type pulleys located on the top plate is one more than the number of V-type pulleys located on the bottom plate, any V-type pulley on the bottom plate is located between two adjacent V-type pulleys on the top plate, the suspension rope passes around the multiple V-type pulleys in turn, one end of the suspension rope is connected to the counterweight, and the other end of the suspension rope is connected to the three-axis rotation assembly.

[0014] The above-mentioned suspended microgravity ground test system, in which the three-axis rotation component includes: a wire lifting device and a rotating shaft 74. The wire lifting device is suspended at one end of the suspension rope. The test prototype is equipped with a rotating shaft 74 that can rotate around its own axis in the front, back, left and right directions. The test prototype is suspended below the wire lifting device through the four rotating shafts 74.

[0015] The above-mentioned suspended microgravity ground test system, wherein the wire lifting device includes: a suspension rope 73, a universal ball head 72 and a long connecting shaft 71, the universal ball head 72 is suspended at one end of the suspension rope, and the two long connecting shafts 71 are both rotatably installed in the universal ball head 72 and are perpendicular to each other, and one end of each long connecting shaft 71 and a rotating shaft 74 are suspended and connected by a suspension rope 73.

[0016] The above-mentioned suspended microgravity ground test system, wherein the deep reinforcement learning comprises the following steps: ① constructing a mathematical model of the simulated spacecraft and the suspension rope; ② using a segmented PD controller as the base controller to compensate for the tracking position error measured by the binocular camera below the carrier platform; ③ using the control data of the base controller as training data, constructing a tracking controller based on deep reinforcement learning, and designing a reward function for position tracking and control smoothness to improve the tracking accuracy and smoothness of the carrier platform relative to the simulated spacecraft.

[0017] Due to the adoption of the above technology, the present invention has the following positive effects compared with the prior art: (1) The present invention adopts a follow-up suspension structure and a follow-up tracking control method based on deep reinforcement learning. The robot's own gravity is offset by a rope mechanism and a pulley set and a counterweight is used. The follow-up motor control based on deep reinforcement learning of visual servoing is used to reduce the error caused by the tilt of the suspension cable and improve the accuracy of gravity compensation.

[0018] (2) The present invention adopts a low-friction transmission mechanism design, and uses a synchronous belt and a linear slide slider mechanism to reduce the friction between the translation structure and the frame, thereby improving the smoothness and precision of movement, and thus improving the simulation accuracy of translation in a microgravity environment.

[0019] (3) The present invention adopts a universal ball head structure design to achieve three-degree-of-freedom free rotation of the prototype, reduce the external traction force on the prototype during rotation, alleviate the influence of the sling pulling force on gravity compensation during rotation, and improve the simulation accuracy of rotation in a microgravity environment.

[0020] (4) The present invention uses standard material selection. The main components of the microgravity ground simulation system are frame structures that can be directly assembled using standard aluminum profiles and assembled using angle brackets, screws, and nuts. This design can greatly reduce the complexity of the manufacturing process, save production costs, shorten production time, and improve test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a design configuration diagram of a suspended microgravity ground test system of the present invention.

[0022] Figure 2 The present invention is a schematic diagram of the installation of a synchronous belt of an X-axis translation device of a suspended microgravity ground test system.

[0023] Figure 3 The figure is a schematic diagram of the installation of the motor of the X-axis translation device of a suspended microgravity ground test system of the present invention.

[0024] Figure 4The figure is a schematic diagram of the installation of the motor of the Y-axis translation device of a suspended microgravity ground test system of the present invention.

[0025] Figure 5 The present invention is a schematic diagram of the installation of an idler wheel of a Y-axis translation device of a suspended microgravity ground test system.

[0026] Figure 6 The figure is a schematic diagram of the installation of a loading platform of a suspended microgravity ground test system of the present invention.

[0027] Figure 7 The figure is a schematic diagram of the suspension of a pulley assembly of a suspended microgravity ground test system of the present invention.

[0028] Figure 8 This is a simulated state diagram of a Z-axis suspension component of a suspended microgravity ground test system of the present invention.

[0029] Figure 9 It is a structural schematic diagram of a Z-axis suspension assembly of a suspended microgravity ground test system of the present invention.

[0030] Figure 10 The three-dimensional spatial coordinate data of the suspended microgravity ground test system of the present invention and the motor displacement data recorded by the suspension simulation system Figure 1 .

[0031] Figure 11 The three-dimensional spatial coordinate data of the suspended microgravity ground test system of the present invention and the motor displacement data recorded by the suspension simulation system Figure 2 .

[0032] Figure 12 It is the basic controller used in the present invention to collect training data for the deep reinforcement learning network controller.

[0033] Figure 13 This is a block diagram of the servo controller based on deep reinforcement learning of visual servoing in the present invention.

[0034] In the accompanying drawings: 13. Upper frame; 16. Base frame; 17. Column structure; 19. Reinforcement beam; 21. Polished rod; 22. Vertical bearing seat; 23. First synchronous pulley; 24. First synchronous belt; 25. First linear slide; 31. Square frame; 32. Second synchronous pulley; 33. Second synchronous belt; 34. X-axis motor; 35. Base; 41. Y-axis motor; 42. Third synchronous pulley; 43. Load-bearing beam; 44. Third synchronous belt; 45. Loading platform; 46. Pallet device; 52. Idle pulley; 53. Second linear slide; 61. Stainless steel stud; 62. Upper part of loading platform; 63. Lower part of loading platform; 64. Pulley block; 71. Long connecting shaft; 72. Universal ball joint; 73. Lifting rope; 74. Rotating shaft. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0036] Please refer to Figures 1 to 13 FIG. 1 shows a suspended microgravity ground test system, which includes: a main support frame, an X-axis translation assembly, a Y-axis translation assembly, a Z-axis suspension assembly, a three-axis rotation assembly, and a loading platform. The main support frame is a cubic structure frame. The X-axis translation assembly is mounted on the top of the main support frame, the Y-axis translation assembly is mounted on the X-axis translation assembly, the loading platform is mounted on the Y-axis translation assembly, and the Z-axis suspension assembly is mounted inside the loading platform. The test prototype is suspended on the Z-axis suspension assembly via the three-axis rotation assembly. The main support frame is used to support the X-axis translation assembly, Y-axis translation assembly, Z-axis suspension assembly, loading platform and test prototype. The X-axis translation assembly is used to realize the displacement of the Y-axis translation assembly on the main support frame along the X-axis direction. The Y-axis translation assembly is used to realize the displacement of the loading platform on the main support frame along the Y-axis direction. The Z-axis suspension assembly is used to realize the displacement of the three-axis rotation assembly and the test prototype along the Z-axis direction. The test prototype is suspended below the three-axis rotation assembly to simulate the suspended microgravity ground test of the test prototype.

[0037] Furthermore, in a preferred embodiment, the main support frame includes: an upper frame 13, a base frame 16, a column structure 17 and a reinforcement beam 19. The upper frame 13 and the base frame 16 are both planar rectangular frame structures. Each corner of the upper frame 13 is connected to each corner of the base frame 16 by a column structure 17. The four column structures 17 are all vertically arranged and have the same length; a reinforcement beam 19 is connected between any two connected profiles on the upper frame 13, and a reinforcement beam 19 is connected between any two connected profiles on the base frame 16; the two profiles at any corner of the upper frame 13 are respectively connected to the column structure 17 at the corner position by a reinforcement beam 19; the two profiles at any corner of the base frame 16 are respectively connected to the column structure 17 at the corner position by a reinforcement beam 19.

[0038] Furthermore, in a preferred embodiment, the X-axis translation assembly includes: a polished rod 21, a vertical bearing seat 22, a first synchronous pulley 23, a first synchronous belt 24, a first linear slide 25, a tray device 46 and a load-bearing beam 43. A polished rod 21 is provided on the left and right profiles of the upper frame 13 respectively. The two polished rods 21 are rotatably mounted on the profile of the upper frame 13 through five vertical bearing seats 22. The two polished rods 21 are parallel to each other. A synchronous pulley 23 is installed at each end of each polished rod 21. The two synchronous pulleys 23 on the front side are connected by a The synchronous belt 24 is connected for transmission, and the two synchronous pulleys 23 on the rear side are connected for transmission through another synchronous belt 24. A tray device 46 is respectively provided on the front profile and the rear profile of the upper frame 13. Each tray device 46 is slidably installed on the profile of the upper frame 13 through a first linear slide rail 25. The tray device 46 on the front side is connected to the synchronous belt 24 on the front side, and the tray device 46 on the rear side is connected to the synchronous belt 24 on the rear side. The two tray devices 46 are symmetrically arranged on the left and right, and the two ends of the load-bearing beam 43 are respectively connected to the two tray devices 46.

[0039] Furthermore, in a preferred embodiment, the X-axis translation assembly also includes: a square frame 31, a second synchronous pulley 32, a second synchronous belt 33, an X-axis motor 34 and a base 35. The square frame 31 is installed on the left or right side of the upper frame 13, and the base 35 is installed at the bottom of the square frame 31. The X-axis motor 34 is installed on the base 35. A second synchronous pulley 32 is installed at the output end of the X-axis motor 34, and another second synchronous pulley 32 is installed on the light rod 21 on the same side of the square frame 31. The two second synchronous pulleys 32 are connected by the second synchronous belt 33. The X-axis motor 34 is used to drive the light rod 21 to rotate and thereby drive the load-bearing beam 43 to move along the X-axis direction.

[0040] Further, in a preferred embodiment, the Y-axis translation assembly includes: a Y-axis motor 41, a third synchronous pulley 42, a third synchronous belt 44, a loading platform 45, an idler wheel 52 and a second linear slide 53. The loading platform 45 is slidably mounted on the load-bearing beam 43 through the second linear slide 53. The Y-axis motor 41 is mounted on a tray device 46. The third synchronous pulley 42 is mounted on the output end of the Y-axis motor 41. The idler wheel 52 is rotatably mounted on another tray device 46. The third synchronous pulley 42 and the idler wheel 52 are connected by the third synchronous belt 44. The loading platform 45 is connected to the third synchronous belt 44. The Y-axis motor 41 is used to drive the loading platform 45 to move along the Y-axis direction.

[0041] Furthermore, in a preferred embodiment, the loading platform 45 also includes: stainless steel studs 61, an upper portion 62 of the loading platform and a lower portion 63 of the loading platform, the upper portion 62 of the loading platform and the lower portion 63 of the loading platform are respectively arranged on the upper and lower sides of the load-bearing beam 43, the upper portion 62 of the loading platform and the lower portion 63 of the loading platform are connected by multiple stainless steel studs 61, the lower surface of the upper portion 62 of the loading platform and the upper surface of the load-bearing beam 43 are slidingly connected by a second linear slide rail 53, the lateral end face of the upper portion 62 of the loading platform is connected to the third synchronous belt 44, and the Z-axis suspension assembly is installed in the lower portion 63 of the loading platform.

[0042] Furthermore, in a preferred embodiment, the loading platform 45 further includes a binocular camera, which is installed on the lower surface of the lower portion 63 of the loading platform and is used to collect data of the test prototype.

[0043] Further, in a preferred embodiment, the Z-axis suspension assembly includes: a pulley group 64 and a counterweight, the pulley group 64 includes: a V-shaped pulley and a suspension rope, the lower part 63 of the loading platform includes: a top plate, a bottom plate and a connecting beam, the top plate and the bottom plate are both arranged horizontally, the lower surface of the top plate and the upper surface of the bottom plate are connected by multiple connecting beams, at least two rotatable V-shaped pulleys are installed on the lower surface of the top plate, and at least one rotatable V-shaped pulley is installed on the upper surface of the bottom plate, and the multiple V-shaped pulleys are located in the same vertical plane, the number of V-shaped pulleys located on the top plate is one more than the number of V-shaped pulleys located on the bottom plate, any V-shaped pulley on the bottom plate is located between two adjacent V-shaped pulleys on the top plate, the suspension rope passes around the multiple V-shaped pulleys in turn, one end of the suspension rope is connected to the counterweight, and the other end of the suspension rope is connected to the three-axis rotation assembly.

[0044] Furthermore, in a preferred embodiment, the three-axis rotation assembly includes: a wire lifting device and a rotating shaft 74. The wire lifting device is suspended at one end of the suspension rope. The test prototype is installed with a rotating shaft 74 that can rotate around its own axis in the front, rear, left and right directions. The test prototype is suspended below the wire lifting device through the four rotating shafts 74.

[0045] Furthermore, in a preferred embodiment, the wire lifting device includes: a suspension rope 73, a universal ball head 72 and a long connecting shaft 71, the universal ball head 72 is suspended at one end of the suspension rope, and the two long connecting shafts 71 are rotatably installed in the universal ball head 72 and are perpendicular to each other, and one end of each long connecting shaft 71 and a rotating shaft 74 are suspended and connected by a suspension rope 73.

[0046] The above are only preferred embodiments of the present invention and are not intended to limit the implementation and protection scope of the present invention.

[0047] The present invention also has the following implementation modes based on the above: In a further embodiment of the present invention, the microgravity simulation system is primarily constructed from aluminum profiles. The overall structure comprises a main support frame, an X-axis translation assembly, a Y-axis translation assembly, a Z-axis suspension assembly, a three-axis rotation assembly, and a loading platform. The main support frame of the simulation system is a cubic structure constructed from long aluminum profiles. Each corner of the cubic frame is connected using corner brackets and additionally features three 45° angled aluminum profiles, or reinforcement beams 19, to minimize deformation of the frame during load-bearing, improve load-bearing capacity, and ensure system operational stability.

[0048] In a further embodiment of the present invention, the X-axis translation assembly and the Y-axis translation assembly based on the synchronous belt drive are installed above the main support frame, mainly consisting of a polished rod, a synchronous pulley, and a vertical bearing seat. The design scheme is divided into X-axis translation and Y-axis Two parts of X-axis translation. In the X-axis translation design, two light rods 21 are located on the left and right sides of the main support frame, and each light rod 21 is supported by five vertical bearing seats 22 to avoid deformation when bearing weight. A first synchronous pulley 23 is installed on both sides of each light rod 21, and the first synchronous pulleys 23 on the left and right sides are matched together using a first synchronous belt 24. A tray device 46 is installed on the first synchronous belt 24 on both sides, and at the same time, the installation positions of the tray devices 46 on both sides are ensured to be symmetrical, so as to jointly support a load-bearing beam 43, which is used to install the Y-axis translation component to achieve translation on the Y-axis. When installing the tray device 46, a synchronous belt pressure plate is used to fix the tray device 46 to the first synchronous belt 24, and a first linear slide rail 25 is installed on each of the front and rear side frames along the moving direction of the first synchronous belt 24, and the tray device 46 is connected to the linear slider of the first linear slide rail 25 to reduce the friction between the tray device 46 and the aluminum profile, and improve the smoothness and precision of the movement of the tray device 46. In order to control the rotation of the polished rod 21, an additional second synchronous pulley 32 is installed on the right polished rod 21, and a platform composed of a square aluminum profile frame and a plywood is built near the polished rod 21, namely the square frame 31. An X-axis motor 34 is installed on the platform, and a second synchronous pulley 32 is installed on the motor shaft. The second synchronous pulley 32 of the X-axis motor 34 and the newly added second synchronous pulley 32 on the polished rod 21 are matched together by a second synchronous belt 33. When the motor shaft rotates, the polished rod 21 will rotate driven by the second synchronous belt 33. By controlling the speed and direction of the X-axis motor 34, the speed and direction of the tray device 46 in the X-axis direction can be controlled.

[0049] In a further embodiment of the present invention, the Y-axis translation design also utilizes a synchronous belt drive in conjunction with a linear slide. The Y-axis synchronous belt drive system is mounted on the tray assembly 46 and the load-bearing beam 43 supported by it, as in the X-axis translation design. The Y-axis synchronous belt drive is transposed and mounted above the two tray assemblies 46. A Y-axis motor 41 is mounted on the upper layer of one tray assembly, with a third synchronous pulley 42 mounted on the motor shaft. A freely rotatable idler pulley 52 for transmission is mounted on the upper layer of the other tray assembly. A third synchronous belt 44 connects the third synchronous pulley 42 on the Y-axis motor 41 to the idler pulley 52 on the other side. To ensure that the loading platform 45 can move freely in the Y-axis direction, two synchronous belt pressure plates are used to press the ends of the third synchronous belt 44 against the loading platform 45. When the motor shaft rotates, the third synchronous belt 44 drives the loading platform 45 in the Y-axis direction. The speed and direction of the loading platform 45 in the Y-axis direction can be controlled by changing the rotation speed and direction of the Y-axis motor 41. Similarly, to ensure smooth movement of the loading platform 45 , a second linear slide rail 53 is installed on the load-bearing beam 43 in the Y-axis direction, and the loading platform 45 is connected to the linear slider of the second linear slide rail 53 .

[0050] In a further embodiment of the present invention, the design scheme for Z-axis translation is implemented based on a pulley block 64 and a counterweight on the loading platform. The loading platform is mainly divided into two layers. The upper part 62 of the loading platform is used to install the synchronous belt pressure plate, and the lower part 63 of the loading platform is installed with a pulley block 64 for hoisting the test prototype. The upper and lower layers are connected by stainless steel studs 61. Three and two V-type pulleys are placed above and below the pulley block 64 respectively. The prototype and the counterweight are placed on both sides of the pulley block 64. The weight of the counterweight is adjusted to balance the gravity of the prototype to simulate the weightless environment in space, thereby realizing Z-axis translation simulation under microgravity conditions. The line for hoisting the prototype and the counterweight, that is, the suspension rope, uses a high-tensile fishing line. The smooth characteristics of the fishing line are used to reduce the friction between it and the V-type pulley. The system's tracking function is mainly achieved by the binocular camera installed under the loading platform. Since the loading platform 45 needs to be constantly moved, in order to prevent the data transmission cable of the binocular camera from sagging due to gravity and affecting the camera's field of view, the camera cable is placed in a nylon drag chain, and the nylon drag chain is fixed on the load-bearing beam 43 in the Y-axis direction.

[0051] In a further embodiment of the present invention, the mechanical diagram of the pulley group gravity balancing mechanism is as follows: Figure 7 As shown, the basic operating principle is to add a counterweight to the load-bearing tray on one side. By keeping the Z-axis suspension assembly and the prototype stationary relative to the loading platform 45 in the Z-axis direction, gravity unloading is achieved. During Z-axis motion simulation, the prototype can be freely floated over long distances on the Z-axis by driving the propulsion device.

[0052] In a further embodiment of the present invention, in order to realize the rotation simulation of the prototype in the three degrees of freedom of XYZ, a counterweight is suspended on one side of the Z-axis suspension assembly, and a three-axis rotation assembly is suspended on the other side. Specifically, the universal ball joint 72 of the three-axis rotation assembly is suspended at the end of the suspension line on one side of the suspension rope used to suspend the prototype. Two long connecting shafts 71 in the horizontal direction are rotatably located in the universal ball joint 72. The two long connecting shafts 71 are perpendicular to each other. The universal ball joint 72 is used to realize continuous rotation of the two connected axes in any direction. The universal ball joint 72 is fixed to the prototype by a lifting device composed of two long connecting shafts 71 in the horizontal direction and a suspension rope 73 in the vertical direction. When the prototype rotates in any degree of freedom, the rotation device can minimize the external traction force on the prototype to ensure the accuracy of gravity compensation and maintain the balance of the prototype.

[0053] In a further embodiment of the present invention, the two-axis rotation mechanism of the universal ball joint 72 is as follows: Figure 8 As shown, in this solution, the resistance and isotropy of the universal ball joint 72 will have a major impact on the realism of the rotation simulation, and the deflection of the two long connecting shafts 71 of pitch and roll must be strictly limited.

[0054] The segmented PD designed as the basic follow-up controller in the present invention is expressed as:

[0055] in, Represents the motor control signal, is the current position of the loading platform, is the simulated spacecraft position captured by the binocular camera, is the follow-up position control error, are the proportional and differential coefficients respectively, To simulate the controller sequence of the spacecraft in different speed ranges, the segmented PD at different speeds will use different proportional, differential, and integral coefficients to ensure high-quality training data for reinforcement learning; The historical data collected by the PD basic controller is converted into a reinforcement learning state vector and normalized and normalized. The deep reinforcement learning controller network is then trained by replaying the PD control data. The training parameters used for reinforcement learning in this invention are shown in Table 1.

[0056] Table 1 Reinforcement learning training parameters

[0057] In a further embodiment of the present invention, the present invention addresses the structural design issues of a microgravity ground simulation system and produces a suspended microgravity simulation system with high precision, low cost, and high reliability. Specifically, the present invention has the following beneficial effects: The follower suspension structure design uses a rope mechanism and pulley system and a counterweight to offset the robot's own gravity. Through high-precision follower motor control based on visual servo deep reinforcement learning, it reduces the error caused by cable tilt and improves the accuracy of gravity compensation.

[0058] The low-friction transmission mechanism design uses a synchronous belt and linear slide slider mechanism to reduce the friction between the translation structure and the frame, improve the smoothness and precision of movement, and thus improve the simulation accuracy of translation in a microgravity environment.

[0059] The universal ball head structural design enables the prototype to rotate freely in three degrees of freedom, reduces the external traction during rotation, alleviates the influence of the sling pulling force on gravity compensation during rotation, and improves the simulation accuracy of rotation in a microgravity environment.

[0060] Standard material selection: The main components of the microgravity ground simulation system are frame structures, constructed directly from standard aluminum profiles and assembled using brackets, screws, and nuts. This design significantly reduces manufacturing complexity, saves costs, shortens production time, and improves testing efficiency.

[0061] In summary, the present invention improves the simulation accuracy of six degrees of freedom in a microgravity environment while ensuring structural strength, greatly reduces the complexity of the manufacturing process, saves production costs, shortens production time, and improves test efficiency. It has high engineering application value and good engineering application prospects.

[0062] In a further embodiment of the present invention, the test process is: S1: Press the prototype Figure 9 It is shown installed on the three-axis rotation assembly on one side of the pulley block.

[0063] S2: Add counterweight to the loading platform on the other side of the pulley assembly until there is no relative motion between the prototype and the suspension assembly and the simulation platform in the Z direction.

[0064] S3: Translation test: Send instructions to the prototype propulsion device to make it translate along the XY axis. At this time, the binocular camera under the loading platform recognizes the position error of the prototype based on vision, and inputs the deep reinforcement learning servo controller, outputs the control signal and controls the drive motor to achieve high-precision servo control of the prototype by the loading platform in the XY axis direction. In step S2, the gravity of the suspension component and the prototype and the gravity of the counterweight have been offset. The prototype can now float freely along the Z axis under the load platform under the drive of its own propulsion device. S4: Rotation Test: The prototype generates rotational torque around the X, Y, and Z axes through its own drive device. Due to the connection of the universal ball joint, the prototype can rotate freely around the Z axis. However, due to the resistance and isotropy of the universal ball joint, the rotation range of the pitch and roll axes must be limited to ±25 degrees to ensure realism.

[0065] In a further embodiment of the present invention, the experimental verification is carried out by comparing the three-dimensional spatial coordinate data collected by the prototype's own inertial navigation sensor with the motor displacement data recorded by the suspension simulation system to verify the tracking accuracy of the visual servo deep reinforcement learning controller proposed by the simulation system. The experimental data are as follows: Figure 10 and Figure 11 shown.

[0066] In a further embodiment of the present invention, the relevant design parameters are as follows: The main support frame measures approximately 2m x 2m x 2m.

[0067] The Y-axis motor 41 of the Y-axis translation assembly controls the movement of the loading platform 45 carrying the prototype in the Y-axis direction.

[0068] The loading platform 45 is mounted on a linear slider of a second linear slide rail 53 on the load-bearing beam 43 .

[0069] The upper frame 13 is composed of four 2300mm aluminum profiles.

[0070] The load-bearing crossbeam 43 used for hoisting the prototype also carries the Y-axis translation assembly and is made of 2400mm aluminum profile.

[0071] A polished rod 21 is installed on each of the left and right sides of the upper frame 12 , and each polished rod 21 is supported by five vertical bearing seats 22 .

[0072] The base frame 16 is composed of four 2300mm aluminum profiles.

[0073] The column structure 17 is composed of four 2000mm aluminum profiles.

[0074] There is a tray device 46 on each of the front and rear sides of the upper frame 13 for carrying the load-bearing beam 43. Each tray device 46 is installed on the linear slider of the first linear slide rail 25 on the same side of the upper frame 13.

[0075] The reinforcement beams 19 are used to reinforce the corners of the main support frame. Each corner is composed of three 800mm 45° inclined aluminum profiles.

[0076] The X-axis translation assembly is slidably mounted on the upper frame 13 and is slidably connected to the upper frame 13 via the support bearing in the vertical bearing seat 22 and the slider of the first linear slide rail 25 .

[0077] The vertical bearing seat 22 is installed on the aluminum profile of the upper frame 13 to support the polished rod 21 to prevent it from deforming when bearing weight.

[0078] A first synchronous pulley 23 is mounted on each polished rod 21. The first synchronous belt 24 is used to cooperate with the first synchronous pulleys 23 of the polished rods 21 on the left and right sides to achieve synchronous rotation of the polished rods 21 on the left and right sides.

[0079] The slider on the first linear slide rail 25 is used to carry the tray device 46 to reduce friction during movement.

[0080] The X-axis motor 34 controls the movement of the load-bearing beam 43 of the suspended prototype in the X-axis direction through the polished rod 21 and the synchronous belt transmission structure.

[0081] The square frame 31 is used to support the X-axis motor 34 , and a plywood base 35 with positioning holes is installed on the square frame 31 to support and fix the X-axis motor 34 .

[0082] The motor shaft of the X-axis motor 34 is mounted with a second synchronous pulley 32 , and the second synchronous pulley 32 and the second synchronous pulley 32 on the right polished rod 21 are driven by a second synchronous belt 33 .

[0083] The X-axis motor 34 is fixed to the plywood base 25 on the square frame 31 by screws.

[0084] The Y-axis motor 41 controls the movement of the loading platform 45 located on the load-bearing beam 43 in the Y-axis direction through a synchronous belt transmission structure.

[0085] A third synchronous pulley 42 is mounted on the motor shaft of the Y-axis motor 41 .

[0086] Both ends of the load-bearing beam 43 are fixed to the tray devices 46 on both sides, and a second linear slide rail 53 is installed on the upper side.

[0087] The loading platform 45 is fixedly connected to the third synchronous belt 44 via a synchronous belt pressing plate, and is installed on the second linear slide rail 53 on the load-bearing beam 43 .

[0088] The idler wheel 52 is mounted on the other side frame of the frame where the Y-axis motor 41 is located. The third synchronous pulley 42 of the Y-axis motor 41 is connected to the idler wheel 52 through a third synchronous belt 44 .

[0089] The two tray units 46 of the X-axis translation assembly are symmetrically mounted, jointly supporting the central load-bearing beam 43. The upper plane of one tray unit 46 is connected to the Y-axis motor 41, the middle plane is connected to the load-bearing beam 43, and the lower plane is mounted on the linear slider of the first linear guide rail 25 on the upper frame 13. The upper and lower planes are connected to the first synchronous belt 24 via a synchronous belt pressure plate. The idler pulley 52 is freely rotatable and mounted on the upper plane of the other tray unit 46. It is installed at the same height as the third synchronous pulley 42 of the Y-axis motor 41. The third synchronous pulley 42 of the Y-axis motor 41 is connected to the idler pulley 52 via the third synchronous belt 44.

[0090] The second linear guide rail 53 is installed above the middle load-bearing beam 43 .

[0091] The loading platform 45 is used to carry the test prototype and the counterweight, and uses the suspension rope, pulley set and counterweight to offset the gravity on the prototype to achieve microgravity, and transmits the translation of the XY axis to the prototype through the traction of the suspension rope.

[0092] The stainless steel stud 61 is used to connect the upper portion 62 of the loading platform and the lower portion 63 of the loading platform. The stainless steel stud 61 has high strength.

[0093] The upper portion 62 of the loading platform is used to install the synchronous belt pressing plate and is fixedly connected to the third synchronous belt 44 , and its lower plane is installed on the slider of the second linear slide rail 53 on the middle load-bearing beam 43 .

[0094] The lower part 63 of the loading platform is equipped with three and two 1.2-inch V-type pulleys respectively. During the hoisting test, the fishing line is passed through the pulley group to connect the prototype with the counterweight to achieve microgravity simulation in the Z-axis direction. Figure 7 shown.

[0095] like Figure 8 and Figure 9 As shown, the universal ball joint 72 can realize the characteristic of continuous rotation of the two connected long connecting shafts 71 in any direction, thereby realizing the three-degree-of-freedom free rotation of the test prototype.

[0096] Figure 9 The figure shows a wire lifting device, which fixes the universal ball head 72 to the prototype through two long connecting shafts 71 and the vertical suspension wires thereon.

[0097] The universal ball joint 72 of the thread lifting device is suspended at the lower end of the loading platform 45 .

[0098] The universal ball joint 72 can make the prototype rotate in any degree of freedom.

[0099] One end of the rotating shaft 74 is fixedly connected to the outer shell of the test prototype, and the middle part is connected to the prototype and the end of the hanging rope 73. The end of the hanging rope 73 can rotate freely around the rotating shaft 74.

[0100] The above are only preferred embodiments of the present invention and do not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A suspended microgravity ground test system, characterized in that: include: The main support frame, X-axis translation assembly, Y-axis translation assembly, Z-axis suspension assembly, three-axis rotation assembly and loading platform. The main support frame is a cubic structure frame. The X-axis translation assembly is installed on the top of the main support frame, the Y-axis translation assembly is installed on the X-axis translation assembly, the loading platform is installed on the Y-axis translation assembly, and the Z-axis suspension assembly is installed in the loading platform. The test prototype is suspended on the Z-axis suspension assembly through the three-axis rotation assembly. The main support frame is used to support the X-axis translation assembly, Y-axis translation assembly, Z-axis suspension assembly, loading platform and test prototype. The X-axis translation assembly is used to realize the displacement of the Y-axis translation assembly on the main support frame along the X-axis direction. The Y-axis translation assembly is used to realize the displacement of the loading platform on the main support frame along the Y-axis direction. The Z-axis suspension assembly is used to realize the displacement of the three-axis rotation assembly and the test prototype along the Z-axis direction. The test prototype is suspended below the three-axis rotation assembly to simulate the suspended microgravity ground test of the test prototype.

2. The suspended microgravity ground test system according to claim 1, characterized in that: The main support frame comprises: an upper frame (13), a base frame (16), a column structure (17) and a reinforcement beam (19), wherein the upper frame (13) and the base frame (16) are both plane rectangular frame structures, and each corner of the upper frame (13) is connected to each corner of the base frame (16) via a column structure (17), and the four column structures (17) are all vertically arranged and have the same length; a reinforcement beam (19) is connected between any two connected profiles on the upper frame (13), and a reinforcement beam (19) is connected between any two connected profiles on the base frame (16); two profiles at any corner of the upper frame (13) are respectively connected to the column structure (17) at the corner position via a reinforcement beam (19); two profiles at any corner of the base frame (16) are respectively connected to the column structure (17) at the corner position via a reinforcement beam (19).

3. The suspended microgravity ground test system according to claim 2, characterized in that: The X-axis translation assembly includes: a polished rod (21), a vertical bearing seat (22), a first synchronous pulley (23), a first synchronous belt (24), a first linear guide rail (25), a tray device (46) and a load-bearing beam (43). A polished rod (21) is provided on the left profile and the right profile of the upper frame (13), respectively. The two polished rods (21) are rotatably mounted on the profile of the upper frame (13) through five vertical bearing seats (22). The two polished rods (21) are parallel to each other. A synchronous pulley (23) is installed at each end of each polished rod (21). The two synchronous pulleys (23) located on the front side are connected by a synchronous belt (24). ) transmission connection, the two synchronous pulleys (23) located at the rear side are connected by another synchronous belt (24), and a tray device (46) is respectively provided on the front side profile and the rear side profile of the upper frame (13). Each tray device (46) is slidably installed on the profile of the upper frame (13) through a first linear slide rail (25). The tray device (46) located at the front side is connected to the synchronous belt (24) on the front side, and the tray device (46) located at the rear side is connected to the synchronous belt (24) on the rear side. The two tray devices (46) are symmetrically arranged on the left and right, and the two ends of the load-bearing beam (43) are respectively connected to the two tray devices (46).

4. The suspended microgravity ground test system according to claim 3, characterized in that: The X-axis translation assembly further comprises: a square frame (31), a second synchronous pulley (32), a second synchronous belt (33), an X-axis motor (34) and a base (35), wherein the square frame (31) is mounted on the left or right side of the upper frame (13), a base (35) is mounted on the bottom of the square frame (31), the X-axis motor (34) is mounted on the base (35), a second synchronous pulley (32) is mounted on the output end of the X-axis motor (34), another second synchronous pulley (32) is mounted on the light rod (21) on the same side as the square frame (31), the two second synchronous pulleys (32) are connected by a second synchronous belt (33), and the X-axis motor (34) is used to drive the light rod (21) to rotate and thereby drive the load-bearing beam (43) to move along the X-axis direction.

5. The suspended microgravity ground test system according to claim 4, characterized in that: The Y-axis translation assembly comprises: a Y-axis motor (41), a third synchronous pulley (42), a third synchronous belt (44), a loading platform (45), an idler wheel (52) and a second linear slide rail (53), wherein the loading platform (45) is slidably mounted on the load-bearing beam (43) via the second linear slide rail (53), the Y-axis motor (41) is mounted on a tray device (46), the third synchronous pulley (42) is mounted on the output end of the Y-axis motor (41), the idler wheel (52) is rotatably mounted on another tray device (46), the third synchronous pulley (42) and the idler wheel (52) are connected by a third synchronous belt (44), the loading platform (45) is connected to the third synchronous belt (44), and the Y-axis motor (41) is used to drive the loading platform (45) to move along the Y-axis direction.

6. The suspended microgravity ground test system according to claim 5, characterized in that: The loading platform (45) further comprises: a stainless steel stud (61), an upper loading platform portion (62) and a lower loading platform portion (63), wherein the upper loading platform portion (62) and the lower loading platform portion (63) are respectively arranged on the upper and lower sides of the load-bearing beam (43), the upper loading platform portion (62) and the lower loading platform portion (63) are connected by a plurality of stainless steel studs (61), the lower surface of the upper loading platform portion (62) and the upper surface of the load-bearing beam (43) are slidingly connected by a second linear slide rail (53), the lateral end surface of the upper loading platform portion (62) is connected to the third synchronous belt (44), and the Z-axis suspension assembly is installed in the lower loading platform portion (63).

7. The suspended microgravity ground test system according to claim 6, characterized in that: The loading platform (45) further includes a binocular camera, which is mounted on the lower surface of the lower portion (63) of the loading platform and is used to collect data of the test prototype.

8. The suspended microgravity ground test system according to claim 6, characterized in that: The Z-axis suspension assembly includes: a pulley group (64) and a counterweight, the pulley group (64) includes: a V-shaped pulley and a suspension rope, the lower part (63) of the loading platform includes: a top plate, a bottom plate and a connecting beam, the top plate and the bottom plate are both arranged horizontally, the lower surface of the top plate and the upper surface of the bottom plate are connected by multiple connecting beams, at least two rotatable V-shaped pulleys are installed on the lower surface of the top plate, and at least one rotatable V-shaped pulley is installed on the upper surface of the bottom plate, the multiple V-shaped pulleys are located in the same vertical plane, the number of V-shaped pulleys located on the top plate is one more than the number of V-shaped pulleys located on the bottom plate, any V-shaped pulley on the bottom plate is located between two adjacent V-shaped pulleys on the top plate, the suspension rope is passed around the multiple V-shaped pulleys in sequence, one end of the suspension rope is connected to the counterweight, and the other end of the suspension rope is connected to the three-axis rotation assembly.

9. The suspended microgravity ground test system according to claim 8, characterized in that: The three-axis rotation assembly includes: a wire lifting device and a rotating shaft (74); the wire lifting device is suspended at one end of a suspension rope; a rotating shaft (74) that can rotate around its own axis is installed in the front, rear, left, and right directions of the test prototype; the test prototype is suspended below the wire lifting device via the four rotating shafts (74).

10. The suspended microgravity ground test system according to claim 9, characterized in that: The wire lifting device comprises: a suspension rope (73), a universal ball head (72) and a long connecting shaft (71), wherein the universal ball head (72) is suspended at one end of the suspension rope, and two long connecting shafts (71) are both rotatably mounted in the universal ball head (72) and perpendicular to each other, and one end of each long connecting shaft (71) is suspended and connected to a rotating shaft (74) through the suspension rope (73).

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