阅读说明：本技术 双层结构的六自由度微重力试验系统 (Six-degree-of-freedom microgravity test system with double-layer structure ) 是由 于泽 霍明英 赵钧 齐乃明 赵策 林桐 冯文煜 于 2021-08-16 设计创作，主要内容包括：一种双层结构的六自由度微重力试验系统,解决了现有航天器地面试验中运动自由度不全面的问题,属于航天器地面试验领域。本发明采用双层结构,上层结构为完整的五自由度模拟器,下层结构为位移支撑平台,下层结构与上层结构之间为气浮平板,通过麦克纳姆轮主动驱动可实现对上层五自由度模拟器的位置跟踪,并且下层结构还具备竖向零重力补偿功能。通过以上的结构实现了航天器地面试验系统的六自由度微重力模拟,同时又通过下层结构的主动跟踪功能减少了附加质量。本发明适用于航天器六自由度地面零重力模拟试验,可满足高精度的动力学与运动学模拟试验要求。(A six-degree-of-freedom microgravity test system with a double-layer structure solves the problem that the degree of freedom of motion is incomplete in the existing spacecraft ground test, and belongs to the field of spacecraft ground tests. The invention adopts a double-layer structure, the upper layer structure is a complete five-degree-of-freedom simulator, the lower layer structure is a displacement supporting platform, an air floating flat plate is arranged between the lower layer structure and the upper layer structure, the position tracking of the upper layer five-degree-of-freedom simulator can be realized through the active driving of Mecanum wheels, and the lower layer structure also has the vertical zero gravity compensation function. The six-degree-of-freedom microgravity simulation of the spacecraft ground test system is realized through the structure, and the additional mass is reduced through the active tracking function of the lower layer structure. The invention is suitable for six-degree-of-freedom ground zero-gravity simulation test of the spacecraft, and can meet the requirements of high-precision dynamics and kinematics simulation test.)

1. A six-degree-of-freedom microgravity test system with a double-layer structure is characterized by comprising an upper five-degree-of-freedom pose simulation platform and a lower zero-gravity position tracking platform;

the lower-layer zero-gravity position tracking platform comprises a dumbbell-shaped air floatation pulley (201), a lower-layer air floatation ball socket (202), a rope (203), a counterweight frame (204), a follow-up air floatation flat plate (205), a follow-up frame lower plate (206), a cylindrical air floatation bearing (207), a lower-layer support base (209), a lower-layer air foot (210) and a Mecanum wheel (211);

two lower-layer air-floating ball sockets (202) are arranged at the bottom of each dumbbell-shaped air-floating pulley (201), the lower-layer air-floating ball sockets (202) are fixed on a lower-layer supporting base (209), and after each lower-layer air-floating ball socket (202) is ventilated, an air film is formed between the air-floating ball socket and the corresponding pulley above the air film;

the follow-up air floating flat plate (205) is fixedly connected with a follow-up frame lower plate (206) through an air floating guide rod (208) to form a follow-up frame;

the counterweight frame (204) is also provided with air floatation guide rods (208), the air floatation guide rods (208) of the follow-up frame and the air floatation guide rods (208) on the counterweight frame (204) both penetrate through the lower-layer supporting base (209), cylindrical air floatation bearings (207) are arranged between each air floatation guide rod (208) and the lower-layer supporting base (209), air floatation guide is formed by the air floatation guide rods (208) and the corresponding cylindrical air floatation bearings (207), and after gas is introduced into the cylindrical air floatation bearings (207), air films are formed between the air floatation guide rods (208) and the cylindrical air floatation bearings (207);

centers of the follow-up frame, the counterweight frame (204) and the lower layer supporting base (209) are on the same line;

each dumbbell-shaped air floatation pulley (201) is hung with a rope (203), one end of each rope (203) is fixedly connected with a counterweight frame (204), the other end of each rope (203) is fixedly connected with a follow-up frame, an upper air foot is arranged at the bottom of the upper five-degree-of-freedom pose simulation platform and is positioned above the follow-up air floatation flat plate (205), an air outlet faces the follow-up air floatation flat plate (205), an air film is formed after ventilation, and the weight of the counterweight frame (204) is equal to the weight of the follow-up frame and the parts above;

the lower-layer air foot (210) is arranged at the bottom of the lower-layer supporting base (209), an air outlet faces downwards, and an air film is formed between the air foot and the marble platform;

mecanum wheels (211) are arranged at the bottom of the lower supporting base (209), the Mecanum wheels (211) are in contact with the marble platform, and the upper five-degree-of-freedom pose simulation platform is always positioned at the center of the follow-up air floating flat plate (205) by driving the Mecanum wheels (211).

2. The dual-layer six-degree-of-freedom microgravity test system according to claim 1, wherein the mecanum wheels (211) are connected with the bottom of the lower support base (209) through springs.

3. The double-layer six-degree-of-freedom microgravity test system according to claim 1, characterized in that the system further comprises 3 weighing sensors (114), wherein the 3 weighing sensors (114) are respectively installed between an upper layer air foot (113) and the bottom of a lower layer support base (209), and stress of the upper layer five-degree-of-freedom pose simulation platform is detected in real time.

4. The double-layer six-degree-of-freedom microgravity test system according to claim 1, wherein the upper-layer five-degree-of-freedom pose simulation platform comprises an air floating ball (101), an upper-layer air floating ball socket (102), an upper-layer support frame and three upper-layer air feet (113);

the upper-layer air-floating ball socket (102) is arranged at the central position of the upper-layer support frame, the air floating ball (101) is arranged on the upper-layer air-floating ball socket (102), and air is communicated between the air floating ball (101) and the upper-layer air-floating ball socket (102) to form an air film;

the three upper-layer air feet (113) are distributed and fixed at the bottom of the upper-layer support frame, the air outlets face the follow-up air floating flat plate (205), and after the upper-layer air feet (113) are filled with air, an air film is formed between the upper-layer air feet (113) and the follow-up air floating flat plate (205).

5. The double-layer six-degree-of-freedom microgravity test system according to claim 4, wherein the upper-layer five-degree-of-freedom pose simulation platform further comprises an air injection module (103), an upper-layer air cylinder (104) and a lower-layer air cylinder (112);

the air injection module (103), the upper-layer air cylinder (104) and the lower-layer air cylinder (112) are all fixed on the upper-layer support frame, the upper-layer air cylinder (104) supplies air for the air injection module (103) and the upper-layer air floating ball socket (102), an air mold is formed between the upper-layer air floating ball socket (102) and the corresponding air floating ball (101), and the air injection module (103) is used for providing thrust;

the lower-layer gas cylinder (112) supplies gas to the upper-layer gas foot (113) through a pipeline, and after the gas foot (113) is ventilated, an air film is formed between the upper-layer gas foot (113) and the follow-up air floatation flat plate (205);

the upper layer gas cylinder (104) and the lower layer gas cylinder (112) are positioned on the upper layer and the lower layer of the upper layer support frame, and the two layers are connected by a support upright post (111).

6. The double-layer six-degree-of-freedom microgravity test system according to claim 5, wherein the upper-layer five-degree-of-freedom pose simulation platform further comprises a leveling module (106), the leveling module (106) is arranged on the upper-layer support frame, the leveling module (106) comprises a motor-driven linear module and a mass block, and the adjustment of the mass center of the upper-layer five-degree-of-freedom pose simulation platform is realized by adjusting the position of the mass block through the motor-driven linear module.

7. The double-layer structure six-degree-of-freedom microgravity test system as claimed in claim 5, wherein the upper-layer five-degree-of-freedom pose simulation platform further comprises a mass flow meter (105), the mass flow meter (105) is arranged in a total gas supply pipeline of the upper-layer gas cylinder (104) and the lower-layer gas cylinder (112), measures the consumed gas mass in the gas injection process and sends the measured gas mass to the lower-layer zero-gravity position tracking platform;

the lower-layer supporting base (209) comprises an upper supporting plate, a lower supporting plate and a supporting rod, the upper supporting plate and the lower supporting plate are fixedly connected through the supporting rod, and a through hole is formed in the middle of the upper supporting plate;

the lower zero-gravity position tracking platform further comprises a linear motor (212), the linear motor (212) is arranged on the supporting lower plate, a rotor of the linear motor (212) penetrates through a through hole of the supporting upper plate and is fixedly connected with the bottom of the follow-up frame lower plate (206), and the rotor of the linear motor (211) is controlled to drive the follow-up frame to move according to the gas quality measured by the mass flow meter (105), so that gravity compensation for consumed gas is realized.

8. The air-floating pulley-based six-degree-of-freedom microgravity test system according to claim 1,

the counterweight frame (204) comprises a counterweight upper plate and a counterweight lower plate;

the counterweight upper plate and the counterweight lower plate are both annular; the counterweight upper plate and the counterweight lower plate are connected through a plurality of air floatation guide rods 207;

the follow-up frame lower plate (206) is annular; the inner diameters of the counterweight upper plate and the counterweight lower plate are larger than the outer diameter of the follow-up lower plate, and the follow-up frame is arranged in a ring of the counterweight frame (204).

9. The six-degree-of-freedom microgravity test system based on the air-floating pulley as claimed in claim 8, wherein one end of the rope (203) passes through a lower counterweight plate of a counterweight frame (204) from a lower supporting base (209) to be connected with the lower counterweight plate;

the other end of the rope (203) penetrates through the lower layer supporting base (209) to be connected with the follow-up lower plate of the follow-up frame.

10. The air-floating pulley-based six-degree-of-freedom microgravity test system according to claim 4, wherein the upper air-floating ball socket (102) and the lower air-floating ball socket (202) are both made of porous materials.

Technical Field

The invention relates to a six-degree-of-freedom microgravity test system with a double-layer structure, and belongs to the field of spacecraft ground tests.

Background

The spacecraft is subjected to extensive ground testing prior to launch. The high-precision distributed spacecraft needs to analyze the control coupling characteristic of the attitude orbit, and complex space missions such as in-orbit capture, in-orbit docking and the like need to evaluate the stress condition of a mechanism in ground tests so as to realize better operation effect in-orbit. The complex space missions put high requirements on ground tests, and the high-fidelity ground tests can analyze and clarify problems possibly occurring on the ground as far as possible and improve the reliability of on-orbit operation. The spacecraft operates in a microgravity environment in orbit, is not restricted by the outside, is a free boundary condition, and has 6 rigid body modes with zero frequency; during ground test, certain constraints are needed to balance the action of the gravity field, and each constraint needs to achieve high precision.

At home and abroad, three-degree-of-freedom or five-degree-of-freedom air floatation simulation test systems are mostly adopted, the simulation of orbit or attitude motion can be only partially completed, and the on-orbit running state of the spacecraft cannot be comprehensively disclosed. At present, no effective method exists for simulating translation motion in the vertical direction or simulating zero gravity state in the vertical direction, and the conventional exploration methods such as a constant force cylinder method, a constant force spring, a suspension method and the like have low simulation precision and limitation, so that the method is not widely applied. In addition, some methods such as the constant force cylinder and the constant force spring are to add the sixth degree of freedom in the vertical direction on the basis of the five-degree-of-freedom simulator, so that the vertical zero-gravity compensation device can increase the additional mass of the ground test simulation system, and the mass characteristic of the aircraft cannot be simulated more truly.

Disclosure of Invention

Aiming at the problem of incomplete freedom of motion in the existing spacecraft ground test, the invention provides a six-freedom-degree microgravity test system with a double-layer structure.

The invention relates to a six-degree-of-freedom microgravity test system with a double-layer structure, which comprises an upper five-degree-of-freedom pose simulation platform and a lower zero-gravity position tracking platform;

the lower zero-gravity position tracking platform comprises a dumbbell-shaped air floatation pulley 201, a lower air floatation ball socket 202, a rope 203, a counterweight frame 204, a follow-up air floatation flat plate 205, a follow-up frame lower plate 206, a cylindrical air floatation bearing 207, a lower support base 209, a lower air foot 210 and a Mecanum wheel 211;

two lower-layer air-floating ball sockets 202 are arranged at the bottom of each dumbbell-shaped air-floating pulley 201, the lower-layer air-floating ball sockets 202 are fixed on a lower-layer supporting base 209, and after each lower-layer air-floating ball socket 202 is ventilated, an air film is formed between the corresponding pulley above the lower-layer air-floating ball socket 202;

the follow-up air floating flat plate 205 is fixedly connected with the follow-up frame lower plate 206 through an air floating guide rod 208 to form a follow-up frame;

the counterweight frame 204 is also provided with air floatation guide rods 208, the air floatation guide rods 208 of the follow-up frame and the air floatation guide rods 208 on the counterweight frame 204 both penetrate through the lower layer supporting base 209, a cylindrical air floatation bearing 207 is arranged between each air floatation guide rod 208 and the lower layer supporting base 209, the air floatation guide rods 208 and the corresponding cylindrical air floatation bearings 207 form air floatation guide, and after the cylindrical air floatation bearings 207 are filled with gas, an air film is formed between the air floatation guide rods 208 and the cylindrical air floatation bearings 207;

centers of the follow-up frame, the counterweight frame 204 and the lower support base 209 are on the same line;

each dumbbell-shaped air floatation pulley 201 is hung with a rope 203, one end of the rope 203 is fixedly connected with a counterweight frame 204, the other end of the rope 203 is fixedly connected with a follow-up frame, an upper air foot is arranged at the bottom of the upper five-degree-of-freedom pose simulation platform and is positioned above the follow-up air floatation flat plate 205, an air outlet faces the follow-up air floatation flat plate 205, an air film is formed after ventilation, and the weight of the counterweight frame 204 is equal to the weight of the follow-up frame and the parts above;

the lower layer air foot 210 is arranged at the bottom of the lower layer supporting base 209, an air outlet faces downwards, and an air film is formed between the air foot and the marble platform;

mecanum wheels 211 are arranged at the bottom of the lower layer supporting base 209, the Mecanum wheels 211 are in contact with the marble platform, and the upper layer five-degree-of-freedom pose simulation platform 1 is always located at the center of the follow-up air floating flat plate 205 by driving the Mecanum wheels 211.

Preferably, mecanum wheels 211 are spring-coupled to the bottom of lower support base 209.

Preferably, the system further comprises 3 weighing sensors 114, wherein the 3 weighing sensors 114 are respectively arranged between the upper layer air foot 113 and the bottom of the lower layer supporting base 209, and the stress of the upper layer five-degree-of-freedom pose simulation platform is detected in real time.

Preferably, the upper-layer five-degree-of-freedom pose simulation platform comprises an air floating ball 101, an upper-layer air floating ball socket 102, an upper-layer support frame and three upper-layer air feet 113;

an upper-layer air-floatation ball socket 102 is arranged at the central position of the upper-layer support frame, an air-floatation ball 101 is arranged on the upper-layer air-floatation ball socket 102, and gas is introduced between the air-floatation ball 101 and the upper-layer air-floatation ball socket 102 to form an air film;

the three upper-layer air feet 113 are distributed and fixed at the bottom of the upper-layer support frame, the air outlets face the follow-up air floating flat plate 205, and after the upper-layer air feet 113 are filled with air, an air film is formed between the upper-layer air feet 113 and the follow-up air floating flat plate 205.

Preferably, the upper five-degree-of-freedom pose simulation platform further comprises an air injection module 103, an upper air cylinder 104 and a lower air cylinder 112;

the air injection module 103, the upper-layer air cylinder 104 and the lower-layer air cylinder 112 are all fixed on the upper-layer support frame, the upper-layer air cylinder 104 supplies air for the air injection module 103 and the upper-layer air floating ball socket 102, an air mold is formed between the upper-layer air floating ball socket 102 and the corresponding air floating ball 101, and the air injection module 103 is used for providing thrust;

the lower-layer gas cylinder 112 supplies gas to the upper-layer gas foot 113 through a pipeline, and after the gas foot 113 is ventilated, a gas film is formed between the upper-layer gas foot 113 and the follow-up air floating flat plate 205; the upper layer gas cylinder 104 and the lower layer gas cylinder 112 are positioned at the upper layer and the lower layer of the upper layer support frame, and the two layers are connected by a support upright 111.

Preferably, the upper five-degree-of-freedom pose simulation platform further comprises a leveling module 106, the leveling module 106 is arranged on the upper support frame, the leveling module 106 comprises a motor-driven linear module and a mass block, and the adjustment of the mass center of the upper five-degree-of-freedom pose simulation platform is realized by adjusting the position of the mass block through the motor-driven linear module.

Preferably, the upper five-degree-of-freedom pose simulation platform further comprises a mass flow meter 105, wherein the mass flow meter 105 is arranged in a total gas supply pipeline of the upper gas cylinder 104 and the lower gas cylinder 112, measures the gas mass consumed in the gas injection process, and sends the gas mass to the lower zero-gravity position tracking platform;

the lower layer supporting base 209 comprises an upper supporting plate, a lower supporting plate and a supporting rod, the upper supporting plate and the lower supporting plate are fixedly connected through the supporting rod, and a through hole is formed in the middle of the upper supporting plate;

the lower zero-gravity position tracking platform further comprises a linear motor 212, the linear motor 212 is arranged on the lower supporting plate, a rotor of the linear motor 212 penetrates through a through hole of the upper supporting plate to be fixedly connected with the bottom of the lower follow-up frame plate 206, and the rotor of the linear motor 211 is controlled to drive the follow-up frame to move according to the gas quality measured by the mass flow meter 105, so that gravity compensation for consumed gas is realized.

Preferably, the weight frame 204 includes a weight upper plate and a weight lower plate;

the counterweight upper plate and the counterweight lower plate are both annular; the counterweight upper plate and the counterweight lower plate are connected through a plurality of air floatation guide rods 207;

the lower follow-up frame plate 206 is annular; the inner diameters of the upper counterweight plate and the lower counterweight plate are larger than the outer diameter of the lower follow-up plate, and the follow-up frame is arranged in the ring of the counterweight frame 204.

Preferably, one end of the string 203 is connected to the lower counterweight plate of the counterweight frame 204 through the lower supporting base 209;

the other end of the string 203 is connected to the lower follower plate of the follower frame through the lower support base 209.

Preferably, the upper air bearing socket 102 and the lower air bearing socket 202 are made of porous material.

The invention has the beneficial effects that the invention adopts a double-layer structure, the upper layer structure is a complete five-degree-of-freedom simulator, the lower layer structure is a displacement supporting platform, an air floating flat plate is arranged between the lower layer structure and the upper layer structure, the position tracking of the upper layer five-degree-of-freedom simulator can be realized through the active driving of Mecanum wheels, and the lower layer structure also has the vertical zero gravity compensation function. The six-degree-of-freedom microgravity simulation of the spacecraft ground test system is realized through the structure, and the additional mass is reduced through the active tracking function of the lower layer structure. The invention is suitable for six-degree-of-freedom ground zero-gravity simulation test of the spacecraft, and can meet the requirements of high-precision dynamics and kinematics simulation test.

Drawings

FIG. 1 is a schematic diagram of a six-degree-of-freedom microgravity test system with a double-layer structure provided by the invention.

FIG. 2 is a schematic structural diagram of an upper five-degree-of-freedom pose simulation platform 1 in FIG. 1;

FIG. 3 is another perspective of FIG. 2;

FIG. 4 is a schematic diagram of the structure of the lower zero-gravity position tracking platform 2 of FIG. 1;

FIG. 5 is a schematic view of the installation structure of the dumbbell-shaped air-bearing pulley of the present invention;

FIG. 6 is a schematic structural diagram of a follower frame in the present invention;

fig. 7 is a schematic structural view of a weight frame in the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.

As shown in fig. 1 to 7, the six-degree-of-freedom microgravity test system with a double-layer structure according to the present embodiment includes an upper five-degree-of-freedom pose simulation platform 1 and a lower zero-gravity position tracking platform 2;

the implementation mode adopts a double-layer structure, the upper five-degree-of-freedom pose simulation platform 1 is a complete five-degree-of-freedom simulator, and the lower zero-gravity position tracking platform 2 is a displacement support platform of the upper five-degree-of-freedom pose simulation platform 1, so that the horizontal position motion of the upper five-degree-of-freedom pose simulation platform 1 is tracked, and the vertical zero-gravity compensation function is realized. The lower zero-gravity position tracking platform 2 of the embodiment comprises a dumbbell-shaped air floatation pulley 201, a lower air floatation ball socket 202, a rope 203, a counterweight frame 204, a follow-up air floatation flat plate 205, a follow-up frame lower plate 206, a cylindrical air floatation bearing 207, a lower support base 209, a lower air foot 210 and a Mecanum wheel 211;

two lower-layer air-floating ball sockets 202 are arranged at the bottom of each dumbbell-shaped air-floating pulley 201, the lower-layer air-floating ball sockets 202 are fixed on a lower-layer supporting base 209, and after each lower-layer air-floating ball socket 202 is ventilated, an air film is formed between the corresponding pulley above the lower-layer air-floating ball socket 202;

the follow-up air floating flat plate 205 is fixedly connected with the follow-up frame lower plate 206 through an air floating guide rod 208 to form a follow-up frame;

the counterweight frame 204 is also provided with air-floatation guide rods 208, the air-floatation guide rods 208 of the follow-up frame and the air-floatation guide rods 208 on the counterweight frame 204 penetrate through the lower-layer supporting base 209, a cylindrical air-floatation bearing 207 is arranged between each air-floatation guide rod 208 and the lower-layer supporting base 209, the air-floatation guide rods 208 and the corresponding cylindrical air-floatation bearings 207 form air-floatation guide, after the cylindrical air-floatation bearings 207 are filled with gas, an air film is formed between the air-floatation guide rods 208 and the cylindrical air-floatation bearings 207, the motion similar to zero friction is realized, the guide function is completed, and the interference on gravity compensation is reduced as much as possible;

centers of the follow-up frame, the counterweight frame 204 and the lower support base 209 are on the same line;

each dumbbell-shaped air floatation pulley 201 is hung with a rope 203, one end of the rope 203 is fixedly connected with a counterweight frame 204, the other end of the rope 203 is fixedly connected with a follow-up frame, the bottom of the upper five-degree-of-freedom pose simulation platform 1 is provided with an upper air foot which is positioned above a follow-up air floatation flat plate 205, an air outlet faces the follow-up air floatation flat plate 205, and an air film is formed after ventilation; the weight of the counterweight frame 204 is equal to the weight of the follow-up frame and the parts above, so that the gravity compensation of the target load can be realized;

in the embodiment, the zero gravity simulation in the vertical direction is realized in a mode of balancing the air floatation pulley and the counterweight;

the lower layer air foot 210 is arranged at the bottom of the lower layer supporting base 209, an air outlet faces downwards, and an air film is formed between the air foot and the marble platform;

the air supply of the cylindrical air bearing 207, the lower air ball socket 202 and the lower air foot 210 in the lower zero-gravity position tracking platform 2 is connected with the air path hose from the ground;

the mecanum wheels 211 are arranged at the bottom of the lower layer supporting base 209, the mecanum wheels 211 are in contact with the marble platform, the upper layer five-degree-of-freedom pose simulation platform 11 is always at the central position of the follow-up air floating flat plate 205 by driving the mecanum wheels 211, the active position following of the upper layer five-degree-of-freedom pose simulation platform 1 is realized by the active driving of the follow-up air floating flat plate 205 and the mecanum wheels 211, when the upper layer five-degree-of-freedom pose simulation platform 1 performs horizontal plane translation motion on the follow-up air floating flat plate 205 under the air injection acting force, the external visual pose measurement can measure the position deviation of the upper layer five-degree-of-freedom pose simulation platform 1 on the follow-up air floating flat plate 205, the mecanum wheels 211 drive the lower layer zero gravity position tracking platform 2 to reduce the deviation, namely the upper layer five-degree-of-freedom pose simulation platform 1 is always kept at the middle position of the follow-up air floating flat plate 205, therefore, the mass of the lower zero-gravity position tracking platform 2 does not participate in the horizontal two-dimensional translational motion of the upper five-degree-of-freedom pose simulation platform 1, and the simulation additional mass is small;

an air floatation flat plate is arranged between the lower layer structure and the upper layer structure of the embodiment, the upper layer structure does not have friction motion on the air floatation flat plate, the Maxam wheel is actively driven to realize position tracking of the upper layer five-freedom-degree simulator, so that the upper layer five-freedom-degree simulator is always positioned at the center of the air floatation flat plate, and the lower layer structure further has a vertical zero gravity compensation function. The six-degree-of-freedom microgravity simulation of the spacecraft ground test system is realized through the structure, and the additional mass is reduced through the active tracking function of the lower-layer platform. In the test process, gas consumed by gas injection can cause the mass change of the upper-layer attitude simulation platform, namely, the compensation target of the gravity compensation mechanism is changed. The system can improve the ground simulation precision of the spacecraft, and can be applied to ground simulation tests of complex space missions such as high-precision distributed spacecraft, in-orbit capture, in-orbit docking and the like.

In the preferred embodiment, the lower air foot 210 supports most of the weight of the whole system, and since there is a high stiffness air film between it and the marble platform on the ground, which is nearly frictionless, some friction between the mecanum wheel 211 and the marble platform can drive the whole system to move, and in order to keep the movement smooth and control the force applied to the mecanum wheel 211, the mecanum wheel 211 is connected to the bottom of the lower support base 209 by a spring. The spring makes the Mecanum wheel contact with the ground all the time, the main weight of the whole structure is supported on the air foot, and the Mecanum wheel has friction with the ground and can drive the lower platform to move.

In a preferred embodiment, the system of the present embodiment further includes 3 weighing sensors 114, and the 3 weighing sensors 114 are respectively installed between one upper layer air foot 113 and the bottom of the lower layer support base 209, so as to detect the stress of the upper layer five-degree-of-freedom pose simulation platform 1 in real time.

In a preferred embodiment, the upper-layer five-degree-of-freedom pose simulation platform 1 of the embodiment comprises an air floating ball 101, an upper-layer air floating ball socket 102, an upper-layer support frame 110 and three upper-layer air feet 113;

the upper layer air-float ball socket 102 is arranged at the central position of the upper layer support frame 110, the air-float ball 101 is arranged on the upper layer air-float ball socket 102, and gas is communicated between the air-float ball 101 and the upper layer air-float ball socket 102 to form an air film;

the three upper-layer air feet 113 are distributed and fixed at the bottom of the upper-layer support frame 110, the air outlets face the follow-up air floating flat plate 205, and after the upper-layer air feet 113 are filled with air, an air film is formed between the upper-layer air feet 113 and the follow-up air floating flat plate 205.

The upper-layer air-floating ball socket 102 is made of porous materials, air with certain pressure is introduced, and a high-rigidity air film is arranged between the upper-layer air-floating ball socket and the 101 air-floating ball, so that the upper-layer five-degree-of-freedom pose simulation platform 1 can rotate around three axes approximately without friction;

in the embodiment, 3 upper-layer air feet 113 support the whole upper-layer five-degree-of-freedom pose simulation platform 1, nitrogen is introduced into the upper-layer air feet 113, and a layer of high-rigidity air film is arranged between the upper-layer air feet 113 and the follow-up air floatation flat plate 205, so that a certain range of motion freedom degree of translation in a horizontal plane is provided for the upper-layer five-degree-of-freedom pose simulation platform 11;

in the preferred embodiment, the upper five-degree-of-freedom pose simulation platform 1 further comprises an air injection module 103, an upper air cylinder 104 and a lower air cylinder 112;

the air injection module 103, the upper-layer air cylinder 104 and the lower-layer air cylinder 112 are all fixed on the upper-layer support frame, the upper-layer air cylinder 104 supplies air for the air injection module 103 and the upper-layer air floating ball socket 102, an air mold is formed between the upper-layer air floating ball socket 102 and the corresponding air floating ball 101, and the air injection module 103 is used for providing thrust;

the lower-layer gas cylinder 112 supplies gas to the upper-layer gas foot 113 through a pipeline, and after the gas foot 113 is ventilated, a gas film is formed between the upper-layer gas foot 113 and the follow-up air floating flat plate 205;

the upper layer gas cylinder 104 and the lower layer gas cylinder 112 are positioned at the upper layer and the lower layer of the upper layer support frame 110, and the two layers are connected by a support upright 111.

The gas injection module 103 of the present embodiment is composed of a nozzle, an electromagnetic valve, and a mounting seat, is a control execution unit of the entire system, generates gas injection reaction force by injecting nitrogen gas of a certain pressure, and supplies gas after being decompressed by high-pressure nitrogen gas in an upper-layer gas cylinder 104;

in a preferred embodiment, the upper-layer five-degree-of-freedom pose simulation platform 1 of the present embodiment further includes a leveling module 106, the leveling module 106 is disposed on the upper-layer support frame 110, the leveling module 106 includes a motor-driven linear module and a mass block, the adjustment of the mass center of the upper-layer five-degree-of-freedom pose simulation platform 1 is realized by adjusting the position of the mass block through the motor-driven linear module, and finally the mass center is adjusted to the position of the rotation center.

As shown in fig. 3, the present embodiment includes two leveling modules 106, and the number and the positions of the leveling modules can be determined according to actual situations.

In a preferred embodiment, the upper five-degree-of-freedom pose simulation platform 1 of the present embodiment further includes a mass flow meter 105, and the mass flow meter 105 is disposed in the total gas supply pipeline of the upper gas cylinder 104 and the lower gas cylinder 112, measures the gas mass consumed in the gas injection process, and sends the measured gas mass to the lower zero-gravity position tracking platform 2;

the lower layer supporting base 209 comprises an upper supporting plate, a lower supporting plate and a supporting rod, the upper supporting plate and the lower supporting plate are fixedly connected through the supporting rod, and a through hole is formed in the middle of the upper supporting plate;

the lower zero-gravity position tracking platform 2 further comprises a linear motor 212 and a linear motor battery 213, the linear motor 212 and the linear motor battery 213 are arranged on the lower supporting plate, a rotor of the linear motor 212 penetrates through a through hole of the upper supporting plate and is fixedly connected with the bottom of the lower follow-up frame plate 206, and the rotor of the linear motor 211 is controlled to drive the follow-up frame to move according to the gas quality measured by the mass flow meter 105, so that gravity compensation for consumed gas is realized. The linear motor battery 213 supplies power to the linear motor 212;

the mass flowmeter 105 is arranged in the main gas supply pipeline after the two gas cylinders are decompressed, can measure the mass flow of the gas flowing through the pipeline in real time and accumulate the mass flow to obtain the mass M of the nitrogen consumed in the gas injection process₁The embodiment also comprises an on-board computer 107, wherein the on-board computer 107 transmits collected information to the lower zero gravity position tracking platform 2 for gravity compensation; linear motor 212 measures M from mass flow meter 105₁The output force compensates the mass of the nitrogen consumed by the air injection in real time and keeps the zero gravity state.

As shown in fig. 7, the weight frame 204 of the present embodiment includes a weight upper plate and a weight lower plate;

the counterweight upper plate and the counterweight lower plate are both annular; the counterweight upper plate and the counterweight lower plate are connected through a plurality of air floatation guide rods 207;

as shown in fig. 6, the follower frame lower plate 206 of the present embodiment is annular; the inner diameters of the upper counterweight plate and the lower counterweight plate are larger than the outer diameter of the lower follow-up plate, and the follow-up frame is arranged in the ring of the counterweight frame 204.

One end of the string 203 of the present embodiment is connected to the lower plate of the counterweight frame 204 through the lower support base 209, and the other end of the string 203 is connected to the lower plate of the follower frame through the lower support base 209.

The upper air bearing socket 102 and the lower air bearing socket 202 of the present embodiment are made of a porous material, and a gas under a certain pressure is introduced to form a high-rigidity gas film above the sockets.

The embodiment also comprises a battery 108 and a power supply 109, wherein the desktop computer 107, the battery 108 and the power supply 109 are arranged on the upper layer support frame 110, so that the functions of power supply, data calculation, data transmission, control instruction sending and the like can be realized, and different electrical elements can be installed according to different task requirements;

although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that features described in different dependent claims and herein may be combined in ways different from those described in the original claims. It is also to be understood that features described in connection with individual embodiments may be used in other described embodiments.