Pneumatic suspension system for simulating zero-gravity environment and control method

Abstract

The invention provides a pneumatic suspension system for simulating a zero-gravity environment and a control method. The pneumatic suspension system comprises a supporting assembly, a suspension assembly and a control system. The supporting assembly comprises a box, a top plate and a spindle, the top plate is arranged in the box, vertical guide rails are arranged on two sides of the box, the spindle penetrates through the top plate and the box bottom, and the top is used for hanging a tested object. The suspension assembly comprises a beam, a cylinder barrel, an air floatation piston, a piston rod and an air source, the beam slides along the guide rail, an airflow channel is arranged in the beam and connected with the air floatation bearing, the air floatation piston is arranged in the cylinder barrel, the cylinder barrel is divided into an upper cavity and a lower cavity, the upper cavity is communicated with the atmosphere, the air source supplies air to the lower cavity, and the two ends of the piston rod are connected with the air floatation piston and the beam respectively. And the control system controls the gas transmission work of the gas source. According to the pneumatic suspension system, friction of the system is effectively reduced, dynamic self-adaptive balance is achieved through the control system, and therefore the more accurate and stable suspension effect is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of zero-gravity environment simulation, and in particular to a pneumatic suspension system and a control method for simulating a zero-gravity environment. Background Art

[0002] With the gradual development of manned space technology and the increasing attention to the development and utilization of outer space, the research and development of zero-gravity environment simulation systems are very active in the field of aerospace technology research. The construction and use of the International Space Station further promoted the development of research in this field. Before aerospace systems such as satellites, aircraft and space stations fly in orbit, in order to ensure the high accuracy and reliability of the system, dynamic tests must be carried out on the ground for each subsystem of their space structure. However, when testing the structural dynamics in the simulated space environment on the ground, it is necessary to support the weight of the test object without applying any constraint. This means that the test object should be suspended freely in the air, so as to achieve the so-called unconstrained "free-free" boundary condition simulation. So far, the methods for simulating the zero-gravity environment in space mainly include free fall method, air flotation method, underwater simulated weightlessness method, and suspension method. Among them, the air suspension simulation method has gradually become a more superior solution due to its simple structure, no influence on modal authenticity, and the ability to achieve long-term zero-gravity suspension simulation. The air suspension method is based on the principle of gas lubrication, using air as a lubricant, and the friction resistance is almost zero. In addition, because pneumatic technology itself has the characteristics of low cost, simple device structure, high power-to-weight ratio, clean and pollution-free, easy to maintain and use, and relatively low requirements for the surrounding environment, it provides extremely favorable conditions for zero-gravity environment simulation.

[0003] In recent years, with the increase in the application scenarios of zero-gravity environment, a variety of zero-gravity environment simulation schemes have been proposed. For example, the Chinese utility patent with application number CN201810229128.3 discloses a zero-gravity suspension test device for cylindrical deployment, which uses a suspension rope to connect to the deployment mechanism at one end and pass through the pulley and counterweight at the other end to balance the self-weight of the mechanism to achieve zero-gravity suspension. The Chinese invention patent with application number CN202310564318.1 discloses a zero-gravity environment simulation device that can compensate for the inertial force of the added mass. The inertial force compensation component detects the motion state of the device and controls the motion follower component and the adjustable air floating platform component to compensate for the inertial force of the added mass. However, these methods affect the control accuracy and stability of zero-gravity simulation due to the friction in the system itself and the difficulty of the system to achieve self-balancing. Summary of the invention

[0004] In view of the difficulty in eliminating the friction existing in the suspension system itself and the inability to achieve adaptive balance, the present invention provides a pneumatic suspension system and control method for simulating a zero-gravity environment. The system not only effectively reduces the friction of the system itself, but also achieves dynamic adaptive balance through the control system, thereby providing a more precise and stable suspension effect.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A pneumatic suspension system for simulating a zero-gravity environment, comprising a support component, a suspension component and a control system;

[0007] The support assembly includes a box, a top plate and a spindle; the box is fixed on a workbench, the top plate is horizontally installed inside the box, and vertical guide rails are respectively provided on the inner walls on both sides of the box below the top plate; one end of the spindle vertically passes through the bottom and top plate of the box in sequence, and the other end is used to hang objects;

[0008] The suspension assembly includes a crossbeam, a cylinder, an air-floating piston, a piston rod and an air source; the crossbeam slides with the vertical guide rails on both sides through grooves at both ends, and the middle part of the crossbeam has a central through hole for accommodating the main shaft, and the main shaft passes through the central through hole and is fixedly connected to the crossbeam; air-floating bearings are arranged in the grooves at both ends of the crossbeam, and the air inlet of the air-floating bearing is connected to the air outlet of the air flow channel opened inside the crossbeam; the upper and lower ends of the cylinder are open, wherein the upper end of the cylinder is fixed to the bottom of the box body, and the lower end of the cylinder is provided with a rear end cover with a first air vent, and the first air vent is connected to the output end pipeline of the air source; the air-floating piston is slidably installed in the cylinder to divide the inner cavity of the cylinder into an upper chamber and a lower chamber The air-floating piston comprises an outer shell and an inner shell, wherein a first cavity connected to the lower chamber is formed between the outer shell and the inner shell; a second cavity is provided inside the inner shell, and the first cavity and the second cavity are connected through a second vent hole provided on the inner shell; one end of the piston rod is connected to the air-floating piston, and the other end is connected to the bottom of the crossbeam after passing through the box body, a third cavity is provided inside the piston rod, a third vent hole and an exhaust hole connecting the second cavity and the third cavity are provided on the piston rod, the second vent hole is connected to the third vent hole pipeline, and the exhaust hole is connected to the air inlet pipeline of the air flow channel inside the crossbeam;

[0009] The control system includes a laser displacement sensor, a proportional directional control valve and a host computer; the laser displacement sensor is used to detect the displacement of the beam per unit time; the proportional directional control valve is arranged on the connecting pipeline between the air source and the first air vent; the host computer is used to calculate the speed of the beam according to the displacement of the beam per unit time, and calculate the acceleration of the beam according to the speed at different times, and when the acceleration of the beam exceeds a predetermined range, the acceleration is returned to the predetermined range by adjusting the opening of the proportional directional control valve.

[0010] Furthermore, a plurality of buffers are installed on the top plate and the box body adjacent to the cross beam to prevent the cross beam from colliding with the top plate, or with the box body.

[0011] Furthermore, the crossbeam is connected by mortise and tenon joints of crossbeam A and crossbeam B, and one end of the piston rod is connected to the bottom of crossbeam A / beam B; crossbeam A is provided with a confluence hole A connected to the airflow channel in crossbeam A, and crossbeam B is provided with a confluence hole B connected to the airflow channel in crossbeam B. After the crossbeam A and beam B are connected by mortise and tenon joints, the confluence hole A and the confluence hole B are butted against each other, so that the airflow channels in crossbeam A and beam B are connected, and the air inlet of the airflow channel in crossbeam A / beam B is connected to the exhaust hole pipeline.

[0012] Furthermore, arc grooves matching the shaft shoulders of the main shaft are respectively provided on the two end surfaces where the cross beam A and the cross beam B abut each other. The shaft shoulders of the main shaft are embedded in the arc grooves on both sides and are fixedly connected to the cross beams A and B through interference fit.

[0013] Furthermore, one end of the piston rod is hinged to the air-floating piston ball, and the other end is hinged to the bottom ball of the beam after passing through the box.

[0014] Furthermore, a plurality of throttling holes are provided on the outer shell, and a gap is left between the outer shell and the inner wall of the cylinder.

[0015] Furthermore, a precision pressure relief valve A, a pressure-stabilizing gas tank, a proportional directional control valve and a buffer gas tank A are sequentially provided along the gas transmission direction of the connecting pipeline between the gas source and the first air vent; the proportional directional control valve comprises a large nominal diameter proportional directional control valve and a small nominal diameter proportional directional control valve connected in parallel between the output end of the pressure-stabilizing gas tank and the input end of the buffer gas tank A; the precision pressure relief valve A is controlled to open and close by the upper computer.

[0016] Furthermore, air bearings sleeved on the main shaft are respectively arranged at the position on the top plate that contacts the main shaft and at the position on the box that contacts the main shaft; the output end of the pressure-stabilizing gas tank is connected to the proportional directional control valve in one way and to the air inlet of the air bearing in the other way; a precision decompression valve B, a buffer gas tank B, a dryer and a filter are sequentially arranged along the gas transmission direction on the connecting pipeline between the output end of the pressure-stabilizing gas tank and the air bearing; the precision decompression valve B is opened and closed by the upper computer.

[0017] Furthermore, a frame-type sealing strip is provided on the working surface of the air bearing in contact with the crossbeam.

[0018] The control method of the pneumatic suspension system for simulating a zero gravity environment as described in any one of the above items comprises the following steps:

[0019] S1: In the initial stage, the upper computer opens the precision decompression valve A and the precision decompression valve B to supply air to the air bearing, and opens the large nominal diameter proportional directional control valve and the small nominal diameter proportional directional control valve to supply air to the lower chamber. When the laser displacement sensor detects that the beam begins to rise, the large nominal diameter proportional directional control valve is closed, and only the small nominal diameter proportional directional control valve (322) is used to control the air intake flow of the lower chamber;

[0020] S2: During the floating and suspension process of the beam, the laser displacement sensor measures the displacement of the beam per unit time in real time and sends it to the host computer. The host computer calculates the speed of the beam according to the displacement of the beam per unit time, and calculates the acceleration of the beam according to the speed at different times. When the acceleration of the beam exceeds the predetermined range, the acceleration is brought back to the predetermined range by adjusting the opening of the proportional directional control valve.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The pneumatic suspension system designed based on the gas lubrication principle of the present invention generates almost zero friction during operation, which can achieve high-precision zero-gravity environment simulation, and the simulation process is clean and efficient, and the system maintenance is convenient.

[0023] 2. The control system in the present invention is equipped with a high-precision laser displacement sensor control system, which can monitor the position change of the beam in real time. Through the feedback control mechanism, the system can accurately capture the acceleration change of the beam and adjust the air pressure in the lower chamber accordingly to ensure that the specimen is stably maintained in the ideal zero-gravity state. This method abandons the inefficiency and uncertainty of the traditional trial and error method and achieves more accurate and reliable control.

[0024] 3. The present invention can also monitor the air pressure in the lower chamber in real time through a pressure sensor, and balance the air pressure in the upper and lower chambers by controlling the air pressure in the lower chamber within a predetermined range, ensuring that the specimen always remains in an ideal zero-gravity state. The two pressure balancing methods are simple and efficient, with fast response speed, and there is no need to consider the deadweight of the hanging object, which greatly simplifies the operation process.

[0025] 4. The crossbeam in the present invention maintains a frictionless state with the guide rail on the inner wall of the box through the air bearing. The air bearing is supplied with gas discharged by the piston rod, and does not require an additional air source connection. Even if the position of the crossbeam is not fixed, it will not be affected. In addition, the high-pressure gas ejected by the air bearing acts on the guide rail, so that the crossbeam has a certain torsion resistance, effectively preventing the twisting phenomenon that may occur during the suspension process, thereby ensuring the stability and accuracy of the suspension performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of the pneumatic suspension system for simulating a zero-gravity environment described in Example 1.

[0027] Figure 2 It is a three-dimensional diagram of the support assembly and the suspension assembly (excluding the air source) of the present invention.

[0028] Figure 3 It is a schematic diagram of the structure of beam A.

[0029] Figure 4 It is a schematic diagram of the structure of beam B.

[0030] Figure 5 Schematic diagram of the assembly of the beam and the guide rail.

[0031] Figure 6 It is the assembly diagram of beam A and main shaft.

[0032] Figure 7 It is a schematic structural diagram of the air bearing of the present invention.

[0033] Figure 8 A cross-sectional view of the interior of a cylinder with an air-floating piston and piston rod.

[0034] Fig. 9 It is an internal cross-sectional view of the air-floating piston and piston rod.

[0035] Fig.10 This is a schematic diagram of the structure of the pneumatic suspension system for simulating a zero-gravity environment described in Example 2.

[0036] The reference numerals are as follows:

[0037] 1-support assembly; 11-box; 12-top plate; 13-spindle; 14-vertical guide rail; 15-buffer; 16-air bearing;

[0038] 2-suspension assembly; 21-crossbeam; 211-crossbeam A; 212-crossbeam B; 23-confluence hole A; 24-confluence hole B; 25-arc groove; 26-cylinder; 27-air floating piston; 28-piston rod; 29-air source; 210-air floating bearing; 211-rear end cover; 212-first vent hole; 213-outer shell; 214-inner shell; 215-first cavity; 216-second cavity; 217-third cavity; 218-second vent hole; 219-third vent hole; 220-exhaust hole; 221-throttle hole; 222-sealing strip;

[0039] 3-control system; 31-host computer; 32-proportional directional control valve; 321-large nominal diameter proportional directional control valve; 322-small nominal diameter proportional directional control valve; 33-laser displacement sensor; 34-pressure sensor; 35-precision pressure relief valve A; 36-pressure stabilizing gas tank; 37-buffer gas tank A; 38-precision pressure relief valve B; 39-buffer gas tank B; 40-dryer; 41-filter. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0041] Example 1

[0042] The pneumatic suspension system for simulating a zero-gravity environment described in this embodiment includes a support component 1, a suspension component 2 and a control system 3. Figure 1 Schematic diagram of the structure of the pneumatic suspension system for simulating a zero-gravity environment described in this embodiment.

[0043] The support assembly 1 includes a box 11, a top plate 12, an air bearing 16 and a spindle 13. The box 11 is fixed on a workbench, the top plate 12 is horizontally installed inside the box 11, and vertical guide rails 14 are respectively provided on the inner walls of both sides of the box 11 below the top plate 12. One end of the spindle 13 vertically passes through the bottom of the box 11 and the top plate 12 in turn, and the other end is used to hang objects. The air bearing 16 is sleeved on the spindle 13 and is respectively installed at the position on the top plate 12 that contacts the spindle 13 and at the position on the box 11 that contacts the spindle 13.

[0044] The suspension assembly 2 includes a crossbeam 21, a cylinder 26, an air-floating piston 27, a piston rod 28 and an air source 29. Figure 2 The figure is a three-dimensional diagram of the support assembly and suspension assembly (excluding the air source) described in this embodiment. The crossbeam 21 in this embodiment is connected by mortise and tenon joints of two parts, crossbeam A211 and crossbeam B212. Figure 3 is the structural diagram of beam A. Figure 4Schematic diagram of the structure of the beam B. The connected beam 21 slides with the vertical guide rails 14 on both sides through the grooves at both ends. Figure 5 The figure is a schematic diagram of the assembly of the crossbeam and the guide rail. Several buffers 15 are installed on the top plate 12 and the box body 11 adjacent to the crossbeam 21 to prevent the crossbeam 21 from colliding with the top plate 12 and the crossbeam 21 and the box body 11. The middle part of the crossbeam 21 has a central through hole for accommodating the main shaft 13, and the two end surfaces where the crossbeam A211 and the crossbeam B212 abut against each other are respectively provided with arc grooves 25 adapted to the shoulders of the main shaft 13. The main shaft 13 passes through the central through hole, and the shoulders of the main shaft 13 are embedded in the arc grooves 25 on both sides, and are fixedly connected to the crossbeam A211 and the crossbeam B212 by interference fit. Figure 6 The figure is a schematic diagram of the assembly of the beam A and the main shaft. The grooves at both ends of the beam 21 are provided with air bearings 210, the air inlet of the air bearing 210 on the beam A211 is connected with the air outlet of the air flow channel opened inside the beam A211, the air inlet of the air bearing 210 on the beam B212 is connected with the air outlet of the air flow channel opened inside the beam B212, and a frame-type sealing strip 222 is provided on the working surface of the air bearing 210 in contact with the beam 21. Figure 7 The schematic diagram of the structure of the air bearing of this embodiment is as follows. The crossbeam A211 is provided with a confluence hole A23 connected to the airflow channel in the crossbeam A211, and the crossbeam B212 is provided with a confluence hole B24 connected to the airflow channel in the crossbeam B212. After the crossbeam A211 and the crossbeam B212 are connected by mortise and tenon joints, the confluence hole A23 and the confluence hole B24 are butted against each other, so that the airflow channels in the crossbeam A211 and the crossbeam B212 are connected.

[0045] The cylinder 26 is open at both ends, wherein the upper end of the cylinder 26 is fixed to the bottom of the housing 11, and the lower end of the cylinder 26 is provided with a rear end cover 211 with a first vent hole 212, and the first vent hole 212 is connected to the output end pipeline of the gas source 29. The air floating piston 27 is slidably installed in the cylinder 26, dividing the inner cavity of the cylinder 26 into an upper chamber and a lower chamber, wherein the inner wall of the upper chamber is provided with a cylinder outlet that connects the upper chamber with the atmosphere. Figure 8 The gas-floating piston 27 comprises an outer shell 213 and an inner shell 214. The outer shell 213 is provided with a plurality of throttle holes 221. A gap is left between the outer shell 213 and the inner wall of the cylinder 26. Fig. 9The figure is an internal cross-sectional view of the air-floating piston and the piston rod. The high-pressure gas entering the lower chamber is sprayed into the gap between the air-floating piston 27 and the inner wall of the cylinder 26 through the throttle hole 221 to form a bearing gas film, so that the air-floating piston 27 is suspended in the cylinder 26. A first cavity 215 connected to the lower chamber is formed between the outer shell 213 and the inner shell 214. The inner shell 214 has a second cavity 216 inside, and the first cavity 215 and the second cavity 216 are connected through a second vent hole 218 provided on the inner shell 214. One end of the piston rod 28 is ball-jointed with the air-floating piston 27, and the other end is ball-jointed with the bottom of the beam A211 after passing through the box body 11. A third cavity 217 is provided inside the piston rod 28, and a third air vent 219 and an exhaust hole 220 connected to the third cavity 217 are provided on the piston rod 28. The second air vent 218 is connected to the third air vent 219 by a pipeline, and the exhaust hole 220 is connected to the air inlet pipeline of the air flow channel in the beam A211.

[0046] The control system 3 includes a host computer 31, a proportional directional control valve, a laser displacement sensor 33, a precision decompression valve A35, a pressure-stabilizing gas tank 36, a buffer gas tank A37, a precision decompression valve B38, a buffer gas tank B39, a dryer 40 and a filter 41. The precision decompression valve A35, the pressure-stabilizing gas tank 36, the proportional directional control valve and the buffer gas tank A37 are sequentially arranged on the connecting pipeline between the gas source 29 and the first vent 212 along the gas transmission direction. The proportional directional control valve includes a large nominal diameter proportional directional control valve 321 and a small nominal diameter proportional directional control valve 322 connected in parallel between the output end of the pressure-stabilizing gas tank 36 and the input end of the buffer gas tank A37. The output end of the pressure-stabilizing gas tank 36 is connected to the proportional directional control valve on one side and to the air inlet of the air bearing 16 on the other side. The precision decompression valve B38, the buffer gas tank B39, the dryer 40 and the filter 41 are sequentially arranged on the connecting pipeline between the output end of the pressure-stabilizing gas tank 36 and the air bearing 16 along the gas transmission direction. The precision decompression valve A35, the precision decompression valve B38, the large nominal diameter proportional directional control valve 321 and the small nominal diameter proportional directional control valve 322 are all controlled to open and close by the host computer 31. The laser displacement sensor 33 is used to detect the displacement of the beam 21 per unit time. The host computer 31 is used to calculate the speed of the beam 21 according to the displacement of the beam 21 per unit time, and calculate the acceleration of the beam 21 according to the speed at different times. When the acceleration of the beam 21 exceeds the predetermined range, the acceleration is returned to the predetermined range by adjusting the opening of the proportional directional control valve. In this embodiment, the host computer 31 is also used to control the opening and closing of the large nominal diameter proportional directional control valve 321 and the small nominal diameter proportional directional control valve 322 according to the movement state of the crossbeam 21.

[0047] The control method of the pneumatic suspension system is characterized by comprising the following steps:

[0048] S1: In the initial stage, the upper computer 31 opens the precision pressure relief valve A35 and the precision pressure relief valve B38 to supply air to the air bearing 16, and opens the large nominal diameter proportional directional control valve 321 and the small nominal diameter proportional directional control valve 322 to supply air to the lower chamber. When the laser displacement sensor 33 detects that the beam 21 begins to rise, the large nominal diameter proportional directional control valve 321 is closed, and only the small nominal diameter proportional directional control valve 322 is used to control the air intake flow of the lower chamber.

[0049] S2: During the floating and suspension process of the beam 21, the laser displacement sensor 33 measures the displacement of the beam 21 per unit time in real time and sends it to the host computer 31. The host computer 31 calculates the speed of the beam 21 according to the displacement of the beam 21 per unit time, and calculates the acceleration of the beam 21 according to the speed at different times. When the acceleration of the beam 21 exceeds a predetermined range, the acceleration is brought back to within a predetermined range by adjusting the opening of the proportional directional control valve.

[0050] The working principle of the pneumatic suspension system described in this embodiment is as follows: the motion state of the beam 21 is detected by the laser displacement sensor 33 installed on the lower side of the top plate 12, that is, when the main shaft 13 suspends the test object, the main shaft 13 drives the beam 21 to move in the vertical direction, and the laser displacement sensor 33 further calculates the real-time speed and acceleration of the beam 21 according to the real-time motion position of the beam 21. When it is detected that the acceleration of the beam 21 exceeds the predetermined range, it means that the force applied by the piston rod 28 fails to balance the deadweight of the main shaft 13, the beam 21 and the suspended object. At this time, the opening of the proportional directional control valve is adjusted according to the value of the acceleration to achieve system adaptive balance. It should be noted that, in general, the force at both ends of the beam 21 is balanced when the acceleration is 0 by default, but it is difficult to control the acceleration to 0 in real-time use. Therefore, this embodiment assumes that the system is in a balanced state when the acceleration is in a very small range. The very small range is the predetermined range in the present invention. The range is set according to the actual accuracy requirements, and no further introduction is given in this embodiment.

[0051] Example 2

[0052] The difference between this embodiment and embodiment 1 is that a high-precision pressure sensor for detecting the air pressure value of the lower chamber is added. The upper computer 31 in this embodiment uses the pressure sensor 34 to monitor the air pressure value of the lower chamber. When the air pressure value of the lower chamber exceeds the predetermined range, the opening of the proportional directional control valve is adjusted to make the air pressure value of the lower chamber return to the predetermined range. The rest of the structure remains unchanged. The specific control method includes the following steps:

[0053] S1: In the initial stage, the upper computer 31 opens the precision pressure relief valve A35 and the precision pressure relief valve B38 to supply air to the air bearing 16, and opens the large nominal diameter proportional directional control valve 321 and the small nominal diameter proportional directional control valve 322 to supply air to the lower chamber. When the laser displacement sensor 33 detects that the beam 21 begins to rise, the large nominal diameter proportional directional control valve 321 is closed, and only the small nominal diameter proportional directional control valve 322 is used to control the air intake flow of the lower chamber.

[0054] S2: During the floating and suspension process of the crossbeam 21, the upper computer 31 uses the pressure sensor 34 to monitor the air pressure value of the lower chamber. When the air pressure value of the lower chamber exceeds the predetermined range, the air pressure value of the lower chamber is returned to the predetermined range by adjusting the opening of the proportional directional control valve.

[0055] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A pneumatic suspension system for simulating a zero gravity environment, characterized in that: It comprises a support component (1), a suspension component (2) and a control system (3); The support assembly (1) comprises a box (11), a top plate (12) and a spindle (13); the box (11) is fixed on a workbench, the top plate (12) is horizontally installed inside the box (11), and vertical guide rails (14) are respectively arranged on the inner walls on both sides of the box (11) below the top plate (12); one end of the spindle (13) vertically passes through the bottom of the box (11) and the top plate (12) in sequence, and the other end is used for hanging objects; The suspension assembly (2) comprises a crossbeam (21), a cylinder (26), an air-floating piston (27), a piston rod (28) and an air source (29); the crossbeam (21) is slidably matched with the vertical guide rails (14) on both sides through grooves at both ends; the middle of the crossbeam (21) has a central through hole for accommodating the main shaft (13); the main shaft (13) passes through the central through hole and is fixedly connected to the crossbeam (21); air-floating bearings (210) are arranged in the grooves at both ends of the crossbeam (21), and the inlet of the air-floating bearings (210) is The air port is connected to the air outlet of the air flow channel opened in the crossbeam (21); the cylinder barrel (26) is open at both ends, wherein the upper end of the cylinder barrel (26) is fixed to the bottom of the box body (11), and the lower end of the cylinder barrel (26) is provided with a rear end cover (211) with a first air vent (212), and the first air vent (212) is connected to the output end pipeline of the air source (29); the air floating piston (27) is slidably installed in the cylinder barrel (26), dividing the inner cavity of the cylinder barrel (26) into an upper chamber and a lower chamber, wherein the upper chamber The inner wall of the cylinder is provided with a cylinder outlet for connecting the upper chamber with the atmosphere; the air-floating piston (27) comprises an outer shell (213) and an inner shell (214); a first cavity (215) connected to the lower chamber is formed between the outer shell (213) and the inner shell (214); a second cavity (216) is provided inside the inner shell (214); the first cavity (215) and the second cavity (216) are connected via a second vent hole (218) provided on the inner shell (214); the piston rod (28) One end of the piston rod (28) is connected to the air floating piston (27), and the other end passes through the box body (11) and is connected to the bottom of the cross beam (21); a third cavity (217) is provided inside the piston rod (28); a third vent hole (219) and an exhaust hole (220) are provided on the piston rod (28) for connecting the second cavity (216) and the third cavity (217); the second vent hole (218) is connected to the third vent hole (219) by a pipeline, and the exhaust hole (220) is connected to the air inlet pipeline of the air flow channel inside the cross beam (21); The control system (3) comprises a laser displacement sensor (33), a proportional directional control valve and a host computer (31); the laser displacement sensor (33) is used to detect the displacement of the crossbeam (21) per unit time; the proportional directional control valve is arranged on a connecting pipeline between an air source (29) and a first vent hole (212); the host computer (31) is used to calculate the speed of the crossbeam (21) according to the displacement of the crossbeam (21) per unit time, and calculate the acceleration of the crossbeam (21) according to the speed at different times, and when the acceleration of the crossbeam (21) exceeds a predetermined range, the acceleration is returned to within the predetermined range by adjusting the opening of the proportional directional control valve.

2. The pneumatic suspension system for simulating a zero gravity environment according to claim 1, characterized in that: A plurality of buffers (15) are installed on the top plate (12) and the box body (11) adjacent to the cross beam (21) to prevent the cross beam (21) from colliding with the top plate (12) and the cross beam (21) from colliding with the box body (11).

3. The pneumatic suspension system for simulating a zero gravity environment according to claim 1, characterized in that: The crossbeam (21) is connected by mortise and tenon joints, namely, a crossbeam A (211) and a crossbeam B (212); one end of the piston rod (28) is connected to the bottom of the crossbeam A (211) / crossbeam B (212); a confluence hole A (23) connected to the airflow channel in the crossbeam A (211) is provided on the crossbeam A (211); a confluence hole B (24) connected to the airflow channel in the crossbeam B (212) is provided on the crossbeam B (212); after the crossbeam A (211) and the crossbeam B (212) are connected by mortise and tenon joints, the confluence hole A (23) and the confluence hole B (24) are butted against each other, so that the airflow channels in the crossbeam A (211) and the crossbeam B (212) are connected, and the air inlet of the airflow channel in the crossbeam A (211) / crossbeam B (212) is connected to the exhaust hole (220) pipeline.

4. The pneumatic suspension system for simulating a zero gravity environment according to claim 3, characterized in that: The two end surfaces of the cross beam A (211) and the cross beam B (212) which abut against each other are respectively provided with arc grooves (25) adapted to the shaft shoulders of the main shaft (13); the shaft shoulders of the main shaft (13) are embedded in the arc grooves (25) on both sides and are fixedly connected to the cross beam A (211) and the cross beam B (212) through interference fit.

5. The pneumatic suspension system for simulating a zero gravity environment according to claim 1, characterized in that: One end of the piston rod (28) is ball-jointed to the air-floating piston (27), and the other end passes through the box body (11) and is ball-jointed to the bottom of the crossbeam (21).

6. The pneumatic suspension system for simulating a zero gravity environment according to claim 1, characterized in that: The outer shell (213) is provided with a plurality of throttling holes (221), and a gap is left between the outer shell (213) and the inner wall of the cylinder (26).

7. The pneumatic suspension system for simulating a zero gravity environment according to claim 1, characterized in that: A precision pressure relief valve A (35), a pressure-stabilizing gas tank (36), a proportional directional control valve and a buffer gas tank A (37) are sequentially provided on the connecting pipeline between the gas source (29) and the first vent hole (212) in the gas transmission direction; the proportional directional control valve comprises a large nominal diameter proportional directional control valve (321) and a small nominal diameter proportional directional control valve (322) connected in parallel between the output end of the pressure-stabilizing gas tank (36) and the input end of the buffer gas tank A (37); the precision pressure relief valve A (35) is controlled to open and close by the upper computer (31).

8. The pneumatic suspension system for simulating a zero gravity environment according to claim 7, characterized in that: An air bearing (16) sleeved on the main shaft (13) is respectively arranged at a position on the top plate (12) that contacts the main shaft (13) and a position on the box body (11) that contacts the main shaft (13); one output end of the pressure-stabilizing gas tank (36) is connected to a proportional directional control valve, and the other output end is connected to an air inlet of the air bearing (16); a precision decompression valve B (38), a buffer gas tank B (39), a dryer (40) and a filter (41) are arranged in sequence along the gas transmission direction on the connecting pipeline between the output end of the pressure-stabilizing gas tank (36) and the air bearing (16); the opening and closing of the precision decompression valve B (38) is controlled by the upper computer (31).

9. The pneumatic suspension system for simulating a zero gravity environment according to claim 1, characterized in that: A frame-type sealing strip (222) is arranged on the working surface of the air bearing (210) in contact with the crossbeam (21).

10. The control method of the pneumatic suspension system for simulating a zero gravity environment according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1: In the initial stage, the upper computer (31) opens the precision decompression valve A (35) and the precision decompression valve B (38) to supply air to the air bearing (16), and opens the large nominal diameter proportional directional control valve (321) and the small nominal diameter proportional directional control valve (322) to supply air to the lower chamber. When the laser displacement sensor (33) detects that the beam (21) begins to rise, the large nominal diameter proportional directional control valve (321) is closed, and the air intake flow of the lower chamber is controlled only by the small nominal diameter proportional directional control valve (322); S2: During the floating and suspension process of the crossbeam (21), the laser displacement sensor (33) measures the displacement of the crossbeam (21) per unit time in real time and sends it to the upper computer (31). The upper computer (31) calculates the speed of the crossbeam (21) according to the displacement of the crossbeam (21) per unit time, and calculates the acceleration of the crossbeam (21) according to the speed at different times. When the acceleration of the crossbeam (21) exceeds a predetermined range, the opening of the proportional directional control valve is adjusted to return the acceleration to within the predetermined range.

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