Suspended air-floating combined three-dimensional microgravity simulation device and method

Abstract

The present invention provides a suspended air-floating combined three-dimensional microgravity simulation device and method, belonging to the field of microgravity simulation and servo control technology. The vertical cylinder and horizontal air foot of the present invention support the simulated aircraft, the Z-axis servo motor is connected to the simulated aircraft through a suspension line, and the X-axis and Y-axis servo motors drive the two-dimensional mobile platform to move in the X- and Y-directions; when simulating free movement, the vertical cylinder and the horizontal air foot balance a part of the gravity, and at the same time, the industrial camera measures the position of the simulated aircraft in real time, drives the X-axis and Y-axis servo motors to make the two-dimensional mobile platform follow the simulated aircraft, keeps the suspension line vertical, measures the tension information through the tension sensor, and drives the Z-axis servo motor to ensure compensation of the gravity of the variable mass simulated aircraft. The present invention can provide a three-dimensional microgravity simulation environment for a variable mass simulated aircraft in real time, solve the problem of the difficulty of giving the initial state of vertical microgravity simulation, and has the advantages of large load bearing, long dynamic simulation stroke, fast tracking, and high simulation accuracy.

Description

Technical Field

[0001] The invention relates to a suspended air-floating combined three-dimensional microgravity simulation device and method, belonging to the technical field of microgravity simulation and servo control. Background Art

[0002] The patent "A ground microgravity simulation system based on constant force spring" (utility model patent, Yan Bo, 20180810) realizes a system design scheme that uses a constant force spring and a hanging wire to compensate for gravity, improves the gravity compensation accuracy of the hanging wire microgravity simulation system, reduces the complexity of the system, and greatly improves operability and maintainability.

[0003] The paper "Design of an Air-floating Simulator for Free-flying Robots" (Optical Precision Engineering, Vol. 27, No. 2, Xu Ce, 20180830) proposed a three-degree-of-freedom free-flying robot simulator based on cold gas propulsion and capable of floating freely, and analyzed and experimentally verified the simulator's carrying capacity based on its working principle.

[0004] The simulator proposed in this paper has a good tracking effect on the reference input and can provide a movable carrier for ground experiments of super-redundant modular robotic arms.

[0005] The paper "Research on Ground Verification System of Space Robot's Six-Degree-of-Freedom Floating Target Capture Function" (PhD dissertation of University of Science and Technology of China, Cha Shihong, 20081105) studied the semi-active space microgravity method, mainly including the study of gravity compensation method in the vertical direction. Combined with the study of gas hydrostatic bearings, a semi-active six-degree-of-freedom simulation satellite was designed, which overcomes the shortcomings of the previous passive hanging wire and cylinder microgravity system and improves the accuracy of the microgravity system.

[0006] The patent "A ground microgravity simulation system based on constant force spring" (utility model patent, Yan Bo, 2018.08.10) realizes a system design scheme that uses a constant force spring and a hanging wire to compensate for gravity. Although it improves the gravity compensation accuracy of the hanging wire microgravity simulation system and reduces the system complexity, the ground simulation aircraft relies on jet movement to reduce its own mass and fails to meet the requirements of real-time and accurate microgravity simulation. This method cannot meet the requirements of variable mass loads.

[0007] The paper "Design of an Air-floating Simulator for Free-flying Robots" (Optical Precision Engineering, Vol. 27, No. 2, Xu Ce, 20180830) proposes a three-degree-of-freedom free-flying robot simulator that can float freely. Although it can achieve gravity compensation or frictionless relative motion conditions to simulate the mechanical environment with small disturbance forces in outer space, the simulator lacks vertical degrees of freedom and cannot meet the requirements of vertical movement of the load, and is not suitable for occasions where the load requires three-dimensional free movement in space.

[0008] The paper "Research on the Ground Verification System of the Space Robot's Six-Degree-of-Freedom Floating Target Capture Function" (PhD dissertation of the University of Science and Technology of China, Cha Shihong, 20081105) designed a semi-active six-degree-of-freedom simulation satellite. Although it achieved gravity compensation in the vertical direction and overcame the shortcomings of the previous passive hanging wire and cylinder microgravity systems, the frictionless cylinder microgravity method limited the weight of the load and could not meet the needs of large loads.

[0009] Based on this, this patent proposes a three-dimensional microgravity simulation device and method based on a suspension air flotation combination. First, a vertical air flotation microgravity simulation method is proposed, which can both accurately position and generate constant pressure. Compared with the traditional hanging wire method, it has the characteristics of strong anti-interference ability and strong robustness. Afterwards, a suspension air flotation combination method is proposed. This method adopts a vertical suspension method and uses visual servoing to track the simulated aircraft to compensate for the gravity of the simulated aircraft. At the same time, the air flotation method is used to eliminate the influence of the ground friction on the simulated aircraft. This combination method has a strong carrying capacity, meets the requirements of large-stroke motion, and is suitable for high-speed and high-maneuverability simulation flight scenarios of simulated aircraft. Summary of the invention

[0010] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art and further provide a suspended air-floating combined three-dimensional microgravity simulation device and method.

[0011] The objective of the present invention is achieved through the following technical solutions:

[0012] A suspended air-floating combined three-dimensional microgravity simulation device, comprising: an X-axis servo motor, a Y-axis servo motor, a Z-axis servo motor, an X-axis linear slide rail, a Y-axis linear slide rail, an industrial camera, a suspension line, a tension sensor, a vertical cylinder, a simulated aircraft, a horizontal air foot, a marble platform and a support frame;

[0013] Among them, a support frame is arranged on the marble platform, and parallel X-axis linear slides are installed on the front and rear sides of the support frame, the Y-axis linear slide is installed on the X-axis linear slide, the vertical cylinder and the horizontal air foot support the simulated aircraft, and the Z-axis servo motor on the two-dimensional mobile platform is connected to the simulated aircraft through a suspension line, the X-axis servo motor drives the movement of the two-dimensional mobile platform in the X direction through gears on the two-dimensional mobile platform, and the Y-axis servo motor drives the movement of the two-dimensional mobile platform in the Y direction through a lead screw; while the simulated aircraft moves freely, the vertical cylinder and the horizontal air foot balance part of the gravity, and the industrial camera measures the position of the simulated aircraft in real time, drives the X-axis servo motor and the Y-axis servo motor to make the two-dimensional mobile platform follow the simulated aircraft, keeps the suspension line vertical, measures the tension information through the tension sensor, and drives the Z-axis servo motor to ensure compensation of the gravity of the variable mass simulated aircraft.

[0014] A suspended air-floating combined three-dimensional microgravity simulation method specifically comprises the following steps:

[0015] Step 1: Provide a vertical air flotation microgravity simulation plan

[0016] The vertical air-floating microgravity simulation method uses a vertical cylinder, an electromagnetic vertical regulating valve, a high-pressure gas cylinder, a ventilation pipe, a grating ruler and a pressure sensor to meet the requirements of vertical microgravity simulation - providing an accurate vertical position at the initial moment and providing a constant air cavity pressure during the ground dynamics simulation to compensate for part of the gravity of the simulated aircraft.

[0017] Step 2: Provide a horizontal two-dimensional microgravity simulation plan

[0018] The horizontal two-dimensional microgravity simulation adopts the air flotation method, using the air foot and marble platform to achieve the two-dimensional microgravity simulation. According to the calculation of relevant experimental data, the air foot structure that meets the requirements can be designed according to the weight of the load, including: the radius of the air foot, the number of throttle holes on the air foot, the diameter of the throttle hole and the thickness of the air film.

[0019] Step 3: Provide a suspension microgravity simulation plan

[0020] The suspended microgravity simulation method uses visual servoing to track horizontal two-dimensional motion and simultaneously compensates for the gravity of the simulated aircraft in real time by measuring the tension of the suspension wire;

[0021] The monocular industrial camera is used to measure the two-dimensional position of the simulated aircraft. Based on the two-dimensional position data of the simulated aircraft, a controller is designed to control the X-axis and Y-axis servo motors so that the two-dimensional mobile platform can track the horizontal two-dimensional movement of the simulated aircraft. At the same time, the tension sensor on the suspension line and the jet mass consumed by the simulated aircraft are used to simulate the vertical microgravity of the simulated aircraft in real time;

[0022] Step 4: Provide a three-dimensional microgravity simulation control method based on suspension and air flotation combination

[0023] For the vertical pneumatic microgravity simulation pressure regulation process: the first process is the vertical floating process, which is regulated by a coarse adjustment valve with a large adjustment range; the second process is the vertical position fine adjustment process, which is controlled by a high-precision fine adjustment valve; the dual-valve segmented Smith predictive control algorithm is used to solve the delay caused by the vertical control valve and ventilation pipe.

[0024] The beneficial effects of the present invention are:

[0025] The suspension-air flotation combination method proposed in the present invention can provide a three-dimensional microgravity simulation environment for a variable-mass simulated aircraft in real time, and has the advantages of a wide range of applications and strong practicality compared to traditional constant-force ground microgravity simulation.

[0026] The vertical cylinder flotation method proposed in the present invention can compensate for a part of the vertical gravity of the simulated aircraft in real time, solves the problem of difficulty in giving the initial state of vertical microgravity simulation, and has three-dimensional microgravity simulation characteristics compared with the traditional two-dimensional microgravity simulation method.

[0027] The suspension air-floating combination method proposed by the present invention can bear heavy loads, has the advantages of long dynamic simulation stroke, rapid tracking, high simulation accuracy, and the like.

[0028] The present invention adopts the dual-valve segmented Smith predictive control algorithm to solve the delay caused by the regulating valve and pipeline, which can not only achieve coarse and fine automatic adjustment, but also solve the time delay and respond in advance. The use of this strategy will bring about the early action of the control output without time delay, which speeds up the control process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the suspended air-floating combined three-dimensional microgravity simulation device of the present invention.

[0030] The reference numerals in the figure are: 1 for the X-axis servo motor, 2 for the Y-axis servo motor, 3 for the Z-axis servo motor, 4 for the X-axis linear slide, 5 for the Y-axis linear slide, 6 for the industrial camera, 7 for the suspension line, 8 for the tension sensor, 9 for the vertical cylinder, 10 for the simulated aircraft, 11 for the horizontal air foot, 12 for the marble platform, 13 for the support frame, and 14 for the two-dimensional mobile platform. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method is given, but the protection scope of the present invention is not limited to the following embodiments.

[0032] like Figure 1 As shown, the suspended air-floating combined three-dimensional microgravity simulation device involved in this embodiment includes: an X-axis servo motor 1, a Y-axis servo motor 2, a Z-axis servo motor 3, an X-axis linear slide 4, a Y-axis linear slide 5, an industrial camera 6, a suspension line 7, a tension sensor 8, a vertical cylinder 9, a simulated aircraft 10, a horizontal air foot 11, a marble platform 12, a support frame 13 and a two-dimensional mobile platform 14;

[0033] A support frame 13 is provided on the marble platform 12, and parallel X-axis linear slides 4 are installed on the front and rear sides of the support frame 13, and the Y-axis linear slide 5 is installed on the X-axis linear slide 4. The vertical cylinder 9 and the horizontal air foot 11 support the simulated aircraft 10. At the same time, the Z-axis servo motor 3 on the two-dimensional mobile platform 14 is connected to the simulated aircraft 10 through the suspension line 7, and the X-axis servo motor 1 drives the movement of the two-dimensional mobile platform 14 in the X direction through gears on the two-dimensional mobile platform 14, and the Y-axis servo motor 2 drives the movement of the two-dimensional mobile platform 14 in the Y direction through a lead screw; while the simulated aircraft 10 moves freely, the vertical cylinder 9 and the horizontal air foot 11 balance part of the gravity, and at the same time, the industrial camera 6 measures the position of the simulated aircraft in real time, drives the X-axis servo motor 1 and the Y-axis servo motor 2 to make the two-dimensional mobile platform 14 follow the simulated aircraft 10, keeps the suspension line 7 vertical, measures the tension information through the tension sensor 8, and drives the Z-axis servo motor 3 to ensure compensation of the gravity of the variable mass simulated aircraft 10.

[0034] Example 1

[0035] Firstly, a vertical air flotation microgravity simulation scheme is given: the vertical air flotation microgravity simulation method adopts vertical cylinders, electromagnetic vertical regulating valves, high-pressure gas cylinders, ventilation pipes, grating scales, pressure sensors and other components. Aiming at the requirements of vertical microgravity simulation - providing accurate vertical position at the initial moment and providing constant air cavity pressure during ground dynamics simulation to compensate for part of the gravity of the simulated aircraft, the vertical microgravity simulation is divided into position control of the floating state before dynamics simulation and constant pressure control of the air cavity in the vertical cylinder during dynamics simulation.

[0036] Give the vertical cylinder cavity pressure

[0037]

[0038] in, is the differential of the air cavity pressure; k is the specific heat ratio, which is an important parameter describing the thermodynamic properties of gas and is related to temperature. Usually k for air is 1.4; R is the ideal gas constant; T0 is the initial temperature; V0 is the initial volume; is the mass differential in the air cavity; P0 is the initial pressure in the air cavity; is the differential of the air cavity volume;

[0039] The gas mass change rate of the gas cavity is controlled by the pressure regulating valve

[0040]

[0041] Among them, K v is the pressure regulating valve gain; P r is the pressure represented by the voltage command of the pressure regulating valve; P is the pressure in the air cavity;

[0042] The dynamic equation of the vertical cylinder is given as

[0043]

[0044] Among them, M L is the simulated aircraft mass; M p is the mass of the vertical cylinder piston rod; F is the simulated aircraft acceleration; f is the Coulomb friction force; P1 is the pressure in the air cavity; A1 is the cross-sectional area of ​​the vertical cylinder piston; P q is standard atmospheric pressure; A r is the cross-sectional area of ​​the piston rod outside the air cavity;

[0045] Give a mathematical description of the ventilation duct

[0046]

[0047] is the gas mass flow rate at the other end of the ventilation pipe; L t is the length of the ventilation pipe; t is the time; μ is the dynamic viscosity of air, D is the diameter of the ventilation duct; T is the temperature; P is the pressure of the ventilation duct; c is the speed of sound; h(t) is the mass flow rate of gas at one end of the ventilation duct;

[0048] According to the knowledge of control theory, the state space equation can be obtained, where the input is the solenoid valve control voltage and the output is the air chamber pressure or the vertical displacement of the vertical cylinder piston.

[0049]

[0050] Among them, x1 is system state 1; x2 is system state 2; x3 is system state 3; x is the displacement of the simulated aircraft; v is the speed of the simulated aircraft; P1 is the pressure in the air cavity;

[0051] Simplify equations (1), (2), (3) and (4) and bring them into equation (5):

[0052]

[0053] in, is the simulated aircraft speed; P a is standard atmospheric pressure; is the differential of the pressure in the air cavity; e is the natural logarithm; μ is the dynamic viscosity of air, D is the diameter of the ventilation pipe; u(t) is the control quantity of the controller;

[0054] That is, the pressure inside the air cavity and the vertical cylinder piston displacement control objects.

[0055] Secondly, a horizontal two-dimensional microgravity simulation scheme is given: the horizontal two-dimensional microgravity simulation adopts the air flotation method, using a horizontal air foot and a marble platform to achieve a two-dimensional microgravity simulation.

[0056] According to calculations and relevant experimental data, the gas foot structure that meets the requirements can be designed according to the weight of the load: gas foot radius, number of throttle holes on the gas foot, throttle hole diameter, gas film thickness, etc.

[0057] Finally, a suspension microgravity simulation scheme is given: the suspension microgravity simulation method uses visual servoing to track horizontal two-dimensional motion, and at the same time compensates the gravity of the simulated aircraft in real time by measuring the tension of the suspension line.

[0058] The monocular industrial camera is used to measure the plane two-dimensional position of the simulated aircraft. Through the two-dimensional position data of the simulated aircraft, the controller is designed to control the X-axis and Y-axis servo motors, so that the two-dimensional mobile platform can follow the horizontal two-dimensional movement of the simulated aircraft. At the same time, the tension sensor on the suspension line and the jet mass consumed by the simulated aircraft are used to simulate the vertical microgravity of the simulated aircraft in real time.

[0059] Give a mathematical description of horizontal two-dimensional motion

[0060]

[0061] Among them, M x is the equivalent translation mass of the two-dimensional mobile platform along the X direction; m is the mass of the suspended object; is the acceleration of the two-dimensional mobile platform along the X direction; C x is the damping coefficient of the two-dimensional mobile platform along the X direction; is the speed of the two-dimensional mobile platform along the X direction; is θ x Angular acceleration; F x M is the motor driving force on the two-dimensional mobile platform along the X direction; y is the equivalent translation mass of the two-dimensional mobile platform along the Y direction; is the acceleration of the two-dimensional mobile platform along the Y direction; C y is the damping coefficient of the two-dimensional mobile platform along the Y direction; is the speed of the two-dimensional mobile platform along the Y direction; l is the length of the suspension line; is θ y Angular acceleration; F y is the motor driving force exerted on the two-dimensional mobile platform along the Y direction; I is the equivalent moment of inertia of the Z-axis servo motor around the axis; is the acceleration of the suspension wire reeling (the second-order differential of the suspension wire length); C l is the damping coefficient along the l direction; is the speed of the suspension line (differential of the suspension line length); g is the acceleration due to gravity; Fl is the suspension wire tension; C s is the equivalent damping coefficient in the suspension wire swing; is θ x Angular velocity; θ x ,θ y is the Euler rotation of the suspension space swing position; is θ y Angular velocity; J x To simulate the aircraft receiving other external forces along X; J y To simulate the aircraft receiving other external forces along the Y direction;

[0062] The horizontal two-dimensional motion is decoupled in the vertical and horizontal directions, and the X and Y directions are symmetrical, so the mathematical description of the two-dimensional motion can be obtained:

[0063]

[0064]

[0065] Wherein, M is the equivalent translation mass of the two-dimensional mobile platform along the X direction or Y direction; C is the damping coefficient of the two-dimensional mobile platform along the X direction or Y direction; l is the length of the suspension line; F is the motor driving force of the two-dimensional mobile platform along the X direction or Y direction; is the angular velocity of θ; θ is the Euler rotation angle of the suspension line's space swing position; J is the other external force received by the simulated aircraft along the X or Y direction;

[0066] Mathematical description of vertical suspension wire tension

[0067]

[0068] Where Q is the radius of the Z-axis servo motor drum;

[0069] Finally, a three-dimensional microgravity simulation control method based on suspension and air flotation is given:

[0070] For the vertical pneumatic microgravity simulation pressure regulation process: the first process is the vertical floating process, which is regulated by a coarse adjustment valve with a large adjustment range, and the second process is the vertical position fine adjustment process, which is controlled by a high-precision fine adjustment valve; as well as the delay caused by the vertical regulating valve and pipeline, the dual-valve segmented Smith predictive control algorithm is used, which can not only achieve coarse and fine automatic adjustment but also solve the time delay well and respond in advance. The use of this strategy will bring about the early action of the control output, without delay, and speed up the control process.

[0071] The above are only preferred specific embodiments of the present invention, which are all different implementations based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A suspended air-floating combined three-dimensional microgravity simulation method, characterized in that: A suspended air-floating combined three-dimensional microgravity simulation device is used, and the simulation device comprises: an X-axis servo motor (1), a Y-axis servo motor (2), a Z-axis servo motor (3), an X-axis linear slide rail (4), a Y-axis linear slide rail (5), an industrial camera (6), a suspension line (7), a tension sensor (8), a vertical cylinder (9), a simulated aircraft (10), a horizontal air foot (11), a marble platform (12), a support frame (13) and a two-dimensional mobile platform (14); A support frame (13) is arranged on the marble platform (12), and parallel X-axis linear slide rails (4) are installed on the front and rear sides of the support frame (13), and the Y-axis linear slide rail (5) is installed on the X-axis linear slide rail (4). A vertical cylinder (9) and a horizontal air foot (11) support the simulated aircraft (10), and at the same time, a Z-axis servo motor (3) on the two-dimensional mobile platform (14) is connected to the simulated aircraft (10) through a suspension line (7), and an X-axis servo motor (1) on the two-dimensional mobile platform (14) drives the two-dimensional mobile platform (14) to move in the X direction through gears, and a Y-axis servo motor (1) drives the two-dimensional mobile platform (14) to move in the X direction through gears. The servo motor (2) drives the two-dimensional mobile platform (14) to move in the Y direction through a lead screw; while the simulated aircraft (10) moves freely, the vertical cylinder (9) and the horizontal air foot (11) balance a part of the gravity, and at the same time the industrial camera (6) measures the position of the simulated aircraft in real time, drives the X-axis servo motor (1) and the Y-axis servo motor (2) to make the two-dimensional mobile platform (14) follow the simulated aircraft (10), keeps the suspension line (7) vertical, measures the tension information through the tension sensor (8), and drives the Z-axis servo motor (3) to ensure compensation of the gravity of the variable mass simulated aircraft (10); The suspended air-floating combined three-dimensional microgravity simulation method specifically comprises the following steps: Step 1: Provide a vertical air flotation microgravity simulation plan The vertical air-floating microgravity simulation method uses a vertical cylinder, an electromagnetic vertical regulating valve, a high-pressure gas cylinder, a ventilation pipe, a grating ruler and a pressure sensor. Aiming at the requirements of vertical microgravity simulation - providing an accurate vertical position at the initial moment and providing a constant air cavity pressure during the ground dynamics simulation to compensate for part of the gravity of the simulated aircraft, the vertical microgravity simulation is divided into the position control of the floating state before the dynamics simulation and the constant pressure control of the air cavity in the vertical cylinder during the dynamics simulation. Step 2: Provide a horizontal two-dimensional microgravity simulation plan The horizontal two-dimensional microgravity simulation adopts the air flotation method, using a horizontal air foot and a marble platform to achieve a two-dimensional microgravity simulation; Step 3: Provide a suspension microgravity simulation plan The suspended microgravity simulation method uses visual servoing to track horizontal two-dimensional motion and simultaneously compensates for the gravity of the simulated aircraft in real time by measuring the tension of the suspension wire; A monocular industrial camera is used to measure the two-dimensional position of the simulated aircraft. Based on the two-dimensional position data of the simulated aircraft, a controller is designed to control the X-axis and Y-axis servo motors so that the two-dimensional mobile platform can track the horizontal two-dimensional movement of the simulated aircraft. At the same time, the tension sensor on the suspension line and the jet mass data consumed by the simulated aircraft are used to simulate the vertical microgravity of the simulated aircraft in real time. Step 4: Provide a three-dimensional microgravity simulation control method based on suspension and air flotation combination For the vertical pneumatic microgravity simulation pressure regulation process: the first process is the vertical floating process, which is regulated by a coarse adjustment valve with a large adjustment range; the second process is the vertical position fine adjustment process, which is controlled by a high-precision fine adjustment valve; the dual-valve segmented Smith predictive control algorithm is used to solve the delay caused by the electromagnetic vertical control valve and the ventilation pipe.

2. The suspended air-floating combined three-dimensional microgravity simulation method according to claim 1, characterized in that: The specific steps of step one are as follows: Give the vertical cylinder cavity pressure in, is the differential of the air cavity pressure; k is the specific heat ratio; R is the ideal gas constant; T0 is the initial temperature; V0 is the initial volume; is the mass differential in the air cavity; P0 is the initial pressure in the air cavity; is the differential of the air cavity volume; The gas mass change rate of the gas cavity is controlled by the pressure regulating valve Among them, K v is the pressure regulating valve gain; P r is the pressure represented by the voltage command of the pressure regulating valve; P is the pressure in the air cavity; The dynamic equation of the vertical cylinder is given as Among them, M L is the simulated aircraft mass; M p is the mass of the vertical cylinder piston rod; F is the simulated aircraft acceleration; f is the Coulomb friction force; P1 is the pressure in the air cavity; A1 is the cross-sectional area of ​​the vertical cylinder piston; P q is standard atmospheric pressure; A r is the cross-sectional area of ​​the piston rod outside the air cavity; Give a mathematical description of the ventilation duct is the gas mass flow rate at the other end of the ventilation pipe; L t is the length of the ventilation pipe; t is the time; μ is the dynamic viscosity of air, D is the diameter of the ventilation duct; T is the temperature; P is the pressure of the ventilation duct; c is the speed of sound; h(t) is the mass flow rate of gas at one end of the ventilation duct; According to the knowledge of control theory, the state space equation can be obtained with the input being the solenoid valve control voltage and the output being the air chamber pressure or the vertical displacement of the vertical cylinder piston. Among them, x1 is system state 1; x2 is system state 2; x3 is system state 3; x is the displacement of the simulated aircraft; v is the speed of the simulated aircraft; P1 is the pressure in the air cavity; Simplify equations (1), (2), (3) and (4) and bring them into equation (5): That is, the pressure in the air cavity and the vertical cylinder piston displacement control object; in, is the simulated aircraft speed; P a is standard atmospheric pressure; is the differential of the pressure in the air cavity; e is the natural logarithm; μ is the dynamic viscosity of air, D is the diameter of the ventilation pipe; u(t) is the control quantity of the controller.

3. The suspended air-floating combined three-dimensional microgravity simulation method according to claim 2, characterized in that: The second step is to design an air foot structure that meets the requirements according to the calculation of relevant experimental data and the weight of the load, including: the radius of the air foot, the number of throttling holes on the air foot, the diameter of the throttling holes and the thickness of the air film.

4. The suspended air-floating combined three-dimensional microgravity simulation method according to claim 3, characterized in that: The specific steps of step three are as follows: Give a mathematical description of horizontal two-dimensional motion Among them, M x is the equivalent translation mass of the two-dimensional mobile platform along the X direction; m is the mass of the suspended object; is the acceleration of the two-dimensional mobile platform along the X direction; C x is the damping coefficient of the two-dimensional mobile platform along the X direction; is the speed of the two-dimensional mobile platform along the X direction; is θ x Angular acceleration; F x M is the motor driving force on the two-dimensional mobile platform along the X direction; y is the equivalent translation mass of the two-dimensional mobile platform along the Y direction; is the acceleration of the two-dimensional mobile platform along the Y direction; C y is the damping coefficient of the two-dimensional mobile platform along the Y direction; is the speed of the two-dimensional mobile platform along the Y direction; l is the length of the suspension line; is θ y Angular acceleration; F y is the motor driving force exerted on the two-dimensional mobile platform along the Y direction; I is the equivalent moment of inertia of the Z-axis servo motor around its axis; C is the acceleration of the hanging line reeling; l is the damping coefficient along the l direction; is the speed of the hanging line; g is the acceleration of gravity; F l is the suspension wire tension; C s is the equivalent damping coefficient in the suspension wire swing; is θ x Angular velocity; θ x ,θ y is the Euler rotation of the suspension line’s swing position in space; is θ y Angular velocity; J x To simulate the aircraft being subjected to other external forces along X; J y To simulate other external forces along the Y direction on the aircraft; The horizontal two-dimensional motion is decoupled in the vertical and horizontal directions, and the X and Y directions are symmetrical, so the mathematical description of the two-dimensional motion can be obtained: Wherein, M is the equivalent translation mass of the two-dimensional mobile platform along the X direction or Y direction; C is the damping coefficient of the two-dimensional mobile platform along the X direction or Y direction; l is the length of the suspension line; F is the motor driving force of the two-dimensional mobile platform along the X direction or Y direction; is the angular velocity of θ; θ is the Euler rotation angle of the suspension line's space swing position; J is the other external forces along the X or Y direction on the simulated aircraft; Mathematical description of vertical suspension wire tension Where Q is the radius of the Z-axis servo motor drum.

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