Suspension type six-degree-of-freedom spacecraft dynamics simulation device

Abstract

The invention relates to a suspension type six-degree-of-freedom spacecraft dynamics simulation device, and the device comprises a translation guide rail which is installed on a support and can translate in the direction of one degree of freedom of a horizontal plane; one end of the telescopic cantilever is fixedly mounted on the translation guide rail, and the other end of the telescopic cantilever is provided with a fixed pulley and can stretch out and draw back in the other-degree-of-freedom direction of the horizontal plane; one end of the hanging spring is used for hanging the three-degree-of-freedom rotating target, and the other end of the hanging spring bypasses the fixed pulley and is connected to the constant-force unloading mechanism; the three-degree-of-freedom rotating target can perform three-degree-of-freedom free rotation around the ball center of the air floating ball bearing; the constant-force unloading mechanism is mounted on the telescopic cantilever and controls the hanging spring to freely move along with the three-degree-of-freedom rotating target in the vertical direction; the hanging spring inclination angle detection system is used for detecting the inclination angle between the hanging spring and the horizontal plane in the two-degree-of-freedom direction; the computer is controlled to drive the translation guide rail and the telescopic cantilever to move, so that the hanging spring keeps unchanged in the vertical direction in the moving process of the three-degree-of-freedom rotating target; and the constant force unloading mechanism is controlled to complete constant force control in the vertical direction.

Description

Technical Field

[0001] The invention relates to a suspended six-degree-of-freedom spacecraft dynamics simulation device, belonging to the technical field of on-orbit maintenance. Background Art

[0002] Low gravity simulation is the basis of ground test and experiment for space exploration, and six-degree-of-freedom dynamic simulation equipment is an important technical means for ground verification of spacecraft orbit and attitude control. The existing satellite six-degree-of-freedom dynamic simulation equipment is a six-degree-of-freedom air-floating platform, which includes a three-axis rotating platform, a translation base and a gravity unloading z-axis. This equipment is used in the ground verification of many missions and has made great contributions to space exploration.

[0003] However, the six-degree-of-freedom air-floating platform itself has certain limitations. Its z-axis simulation accuracy and stroke are limited by machinery and control, and the additional mass brought by its base and z-axis leads to different masses of translational and rotational parts. Especially with the research progress of space precision control, on-orbit assembly and maintenance projects, high-precision dynamic simulation of small spacecraft is required. Summary of the invention

[0004] The technical problem solved by the present invention is to provide a suspended six-degree-of-freedom spacecraft dynamics simulation device for solving the accuracy problem of the simulation of the six-degree-of-freedom kinematics and dynamics of a small spacecraft, and can also reduce the production cost and reduce the complexity of the mechanism and control.

[0005] The technical solution of the present invention is: a suspended six-degree-of-freedom spacecraft dynamics simulation device, the six degrees of freedom include three degrees of freedom translation and three degrees of freedom rotation, the three degrees of freedom translation is the movement in the two coordinate axis directions of the horizontal plane and the vertical direction, the three degrees of freedom rotation refers to the rotation around the two coordinate axis directions of the horizontal plane and the vertical direction, the device includes a bracket, a translation guide rail, a telescopic cantilever, a hanging wire, a fixed pulley, a constant force unloading mechanism, a hanging wire inclination detection system, and a three-degree-of-freedom rotation target;

[0006] The translation guide rail is installed on the bracket, located on the horizontal plane, and can translate along a coordinate axis of the horizontal plane;

[0007] The telescopic cantilever has one end fixedly mounted on the translation guide rail. As the translation guide rail moves horizontally, a fixed pulley is installed on the other end. The telescopic cantilever can be extended and retracted along another coordinate axis direction on the horizontal plane. The two-dimensional movement of the telescopic cantilever on the horizontal plane can follow the two-dimensional movement of the unloading target on the horizontal plane.

[0008] A hanging wire, one end of which is used to suspend the air-floating ball bearing of the three-degree-of-freedom rotating target, and the other end of which passes over a fixed pulley installed at one end of the telescopic cantilever, extends along the direction of the telescopic cantilever, and is connected to the constant force unloading mechanism;

[0009] The three-degree-of-freedom rotating target has a built-in air-floating ball bearing mechanism. The three-degree-of-freedom rotating target shell can freely rotate with three degrees of freedom around the center of the air-floating ball bearing. The air supply pipe supplies air to the air-floating ball bearing mechanism.

[0010] The constant force unloading mechanism is installed on the telescopic cantilever. It adopts the constant force control principle to control the hanging wire to move freely in the vertical direction following the three-degree-of-freedom rotation target, and always maintains a constant unloading tension to achieve vertical weightlessness simulation;

[0011] The hanging wire inclination angle detection system is used to detect the angle between the plane formed by the hanging wire deviating from the translation guide rail direction and the vertical direction, and the angle between the plane formed by the hanging wire deviating from the vertical guide rail direction and the vertical direction;

[0012] The control computer performs feedback closed-loop calculation based on the measurement results of the hanging wire inclination detection system, obtains motion control instructions, drives the translation guide rail and telescopic cantilever to move, so that the hanging wire maintains the vertical direction unchanged during the movement of the three-degree-of-freedom rotating target, thereby realizing the horizontal position tracking of the three-degree-of-freedom rotating target.

[0013] Preferably, the constant force unloading mechanism comprises a roller, a motor, and a dynamometer;

[0014] The motor is used to control the rotation of the drum; the hanging wire is fixed and wound on the drum; the dynamometer is used to measure the tension on the hanging wire and is used for constant force closed-loop feedback control of the constant force unloading mechanism.

[0015] Preferably, the three-degree-of-freedom rotation target includes an air pipe interface, a hanging wire interface, a ducted thruster, a first balancing mechanism, an industrial computer, an air-floating ball bearing, a second balancing mechanism, an inertial measurement unit, and an air supply pipe;

[0016] Air-floating ball bearings, through air-floating lubrication, enable the three-degree-of-freedom rotating target to rotate in three degrees of freedom;

[0017] Air pipe interface, used for supplying air to the air-floating ball bearing, connected to the air supply pipe;

[0018] Hanging wire interface, used to connect the hanging wire;

[0019] The ducted thruster is an actuator in a three-degree-of-freedom rotating target, used to provide thrust to the target and control its translational position movement and rotational attitude;

[0020] The first balancing mechanism and the second balancing mechanism are used to adjust the projection position of the mass center of the three-degree-of-freedom rotating target on the horizontal plane; when the mass center coincides with the center of the air-floating ball bearing, the three-degree-of-freedom rotating target after suspension completely eliminates the influence of gravity and can simulate the free rotation state on orbit;

[0021] Industrial computer, used to control the on / off status of each ducted thruster.

[0022] Preferably, the ducted thruster is a unidirectional thruster.

[0023] Preferably, the number of the ducted thrusters is , and each degree of freedom is controlled by two pairs of ducted thrusters.

[0024] Preferably, the air-floating ball bearing comprises a hanging rope joint, a convex ball air pipe joint, a rotating concave ball and a suspended convex ball;

[0025] The suspended convex ball is fixedly connected to the convex ball hanging wire joint, and the convex ball hanging wire joint is the suspension connection end of the three-degree-of-freedom rotating target; the convex ball air pipe joint is used to connect the suspended convex ball and supply air to the suspended convex ball. An air outlet is provided on the suspended convex ball, and an air floating lubrication layer is formed on the contact surface between the suspended convex ball and the rotating concave ball, so that the suspended convex ball and the rotating concave ball can realize frictionless free rotation;

[0026] The rotating concave sphere is connected to a structural member of a three-degree-of-freedom rotating target through a concave sphere flange.

[0027] Preferably, the three-degree-of-freedom rotating target can rotate 360° around the vertical direction in an air-floating state, and can rotate around the guide rail direction on the horizontal plane and the direction perpendicular to the guide rail.

[0028] Preferably, the air-floating ball bearing comprises a convex ball flange, a rotating convex ball, a suspended concave ball, a concave ball hanging wire joint, and a concave ball air path interface;

[0029] The concave ball hanging wire joint and the concave ball air path interface are fixed on the suspended concave ball, the convex ball flange is fixedly installed with the rotating convex ball, and the rotating convex ball is connected and fixed with the structural member of the three-degree-of-freedom rotating target through the convex ball flange; the rotating convex ball is located inside the suspended concave ball, and the gas is ejected from the suspended concave ball to form an air-floating lubrication layer between the suspended concave ball and the rotating convex ball, so that the suspended concave ball and the convex ball flange can achieve frictionless free rotation.

[0030] Preferably, the first balancing mechanism and the second balancing mechanism adjust the center of mass position of the three-degree-of-freedom rotating target by moving the mass of the slider.

[0031] The beneficial effects of the present invention compared with the prior art are:

[0032] (1) The suspended six-degree-of-freedom spacecraft dynamics simulation device designed by the present invention realizes high-precision six-degree-of-freedom dynamics simulation of spacecraft targets. Compared with the existing six-degree-of-freedom air-floating platform, this method has the characteristics of high dynamics simulation accuracy and no need for a granite platform, which is convenient for conducting ground tests of on-orbit maintenance and repair in the laboratory.

[0033] (2) The suspended air-floating ball bearing structure designed by the present invention realizes high-precision simulation of three-degree-of-freedom rotation of small satellite targets through suspension, ensures the accuracy of attitude dynamics simulation, and facilitates attitude control algorithm verification.

[0034] (3) The translational following mechanism designed in the present invention comprises three degrees of freedom, wherein the vertical direction adopts a constant force control method to achieve high-precision gravity unloading; the two degrees of freedom in the horizontal direction are realized by the translational following control principle, that is, the inclination angle of the hanging wire is detected, and the closed-loop control of the translational mechanism makes the hanging wire always remain in the vertical direction, thereby achieving horizontal position following. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0036] Figure 2 Schematic diagram of a three-degree-of-freedom rotation target according to an embodiment of the present invention.

[0037] FIG. 3 is a schematic diagram of the structure of a suspended convex ball bearing according to an embodiment of the present invention.

[0038] Figure 4 It is a schematic diagram of the structure of a suspended concave ball bearing according to an embodiment of the present invention.

[0039] FIG. 5( a ) is a schematic diagram of an xoy plane of an embodiment of the present invention.

[0040] FIG5( b ) is a schematic diagram of a zoy plane or a zox plane according to an embodiment of the present invention.

[0041] FIG5(c) is a schematic diagram of the thruster position according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0043] The suspended low-gravity simulation device based on constant tension has been used in mechanical arm gravity unloading, etc., and is a simple, reliable and effective low-gravity simulation device. Two suspended air-floating ball bearing devices are proposed in the six-degree-of-freedom spacecraft dynamics simulator of the present invention, and the three-degree-of-freedom translational dynamics simulation is realized by using the constant tension unloading method, and the three-degree-of-freedom rotational dynamics simulation is realized by using the suspended air-floating ball bearing.

[0044] Figure 1The present invention provides a schematic diagram of the overall structure of a specific embodiment of a suspended six-degree-of-freedom spacecraft dynamics simulator. The six degrees of freedom include three degrees of freedom translation and three degrees of freedom rotation. The three degrees of freedom translation is the movement in the two coordinate axes of the horizontal plane and the vertical direction, and the three degrees of freedom rotation refers to the rotation around the two coordinate axes of the horizontal plane and the vertical direction. From the perspective of the simulation principle of the six-degree-of-freedom spacecraft dynamic characteristics, this embodiment is different from the general air-floating platform simulation method. This embodiment realizes three-dimensional translation through a suspended active translation follower system and realizes three-degree-of-freedom rotation through a suspended ball bearing. In terms of the simulation effect of the six-degree-of-freedom spacecraft dynamic characteristics, (1) the simulator described in the present invention does not have the base and z-axis parts required for the translation of the air-floating platform simulation method, and has a light weight; (2) the mass of the translation part is consistent with the mass of the rotation part, which is closer to the real spacecraft dynamics in principle; (3) the free movement of the z-axis part is unloaded by the hanging wire to unload the mass of the spacecraft, and its movement stroke is only limited by the height of the bracket, and the stroke length is much longer than the z-axis of the existing six-degree-of-freedom air-floating platform.

[0045] like Figure 2 , The device of this embodiment is composed of a suspended three-dimensional translation tracking system and an air-floating three-degree-of-freedom rotation target, specifically including a bracket 1, a translation guide rail 2, a telescopic cantilever 3, a constant force unloading hanging wire 4, a hanging wire, a fixed pulley, a hanging wire inclination detection system 5, and a three-degree-of-freedom rotation target 7;

[0046] Among them, the bracket 1 is vertically installed on the ground and is used to install a three-degree-of-freedom translation tracking suspension unit; the three-degree-of-freedom translation tracking suspension unit includes a translation guide rail 2, a telescopic cantilever 3, a constant force unloading mechanism 4, a hanging wire, a fixed pulley, and a hanging wire inclination detection system 5;

[0047] The translation guide rail 2 is installed on the bracket 1 and can translate along a coordinate axis direction of the horizontal plane;

[0048] The telescopic cantilever 3 has one end fixedly mounted on the translation guide rail 2 and the other end is provided with a fixed pulley, and can be extended and retracted along another degree of freedom direction of the horizontal plane;

[0049] A hanging wire, one end of which is used to suspend the three-degree-of-freedom rotating target 7, and the other end of which passes over a fixed pulley installed at one end of the telescopic cantilever 3, and extends along the telescopic cantilever 3 until it is connected to the constant force unloading mechanism 4;

[0050] The three-degree-of-freedom rotating target 7 has a built-in air-floating ball bearing mechanism, which can freely rotate with three degrees of freedom around the center of the air-floating ball bearing;

[0051] The low-pressure air pipe 6 is suspended on the bracket and supplies air to the three-degree-of-freedom rotating target suspended on the hanging wire, and moves up and down with the three-degree-of-freedom rotating target;

[0052] The constant force unloading mechanism 4 is installed on the telescopic cantilever 3, and adopts the constant force control principle to control the hanging wire to move freely in the vertical direction following the three-degree-of-freedom rotation target, and always maintain a constant unloading tension to achieve vertical weightlessness simulation;

[0053] The hanging wire inclination detection system 5 is used to detect the inclination of the hanging wire and the horizontal plane in two degrees of freedom caused by the horizontal movement of the three-degree-of-freedom rotating target 7;

[0054] The control computer obtains the motion control instruction based on the feedback closed-loop calculation of the inclination angle of the hanging wire and the horizontal plane in two degrees of freedom directions obtained by the hanging wire inclination detection system 5, and drives the translation guide rail 2 and the telescopic cantilever 3 to move, so that the hanging wire keeps the vertical direction unchanged during the movement of the three-degree-of-freedom rotating target 7, thereby realizing the horizontal position tracking of the three-degree-of-freedom rotating target 7.

[0055] It can be seen that among the three translational degrees of freedom of the spacecraft dynamics simulation device, the two horizontal degrees of freedom are simulated and realized by the bracket 1, the translation guide rail 2, the telescopic cantilever 3 and the hanging wire inclination detection system 5; the vertical degree of freedom is realized by the constant force unloading mechanism 4.

[0056] The constant force unloading mechanism 4 includes a roller, a motor, and a dynamometer;

[0057] The motor is used to control the rotation of the drum; the hanging wire is fixed and wound on the drum; the dynamometer is used to measure the tension on the hanging wire.

[0058] The three-degree-of-freedom rotating target 7 is a rotating platform used to simulate the dynamics of a spacecraft. It is used to simulate the three-degree-of-freedom rotation of the target and is equipped with an inertial measurement unit (IMU) and thrusters to achieve three-degree-of-freedom attitude control.

[0059] The three-degree-of-freedom rotation target 7 includes an air pipe interface 8, a hanging wire interface 9, a ducted thruster 10, a first balancing mechanism 11, an industrial computer 12, an air-floating ball bearing 13, a second balancing mechanism 14, and an inertial measurement unit 26;

[0060] The air-floating ball bearing 13 enables the three-degree-of-freedom rotating target to rotate in three degrees of freedom through air-floating lubrication;

[0061] The air pipe interface 8 is used to supply air to the air-floating ball bearing 13 and is connected to the air supply pipe 6;

[0062] The suspension wire interface 9 is a connection suspension interface for supplying air to the ball bearing inside the three-degree-of-freedom rotating target and is used to connect the suspension wire;

[0063] The ducted thruster 10 is an actuator in a three-degree-of-freedom rotating target, used to provide thrust to the target and control its translational position movement and rotational attitude;

[0064] The first balancing mechanism 11 and the second balancing mechanism 14 are used to adjust the position of the mass center of the three-degree-of-freedom rotating target 7 in the horizontal plane; when the mass center coincides with the center of the air-floating ball bearing 13, the three-degree-of-freedom rotating target after suspension completely eliminates the influence of gravity and can simulate the free rotation state on orbit;

[0065] The industrial computer 12 is used to control the switch state of each ducted thruster 10, and further control the attitude of the target for three-degree-of-freedom rotation.

[0066] The ducted thruster 10 is a unidirectional thruster.

[0067] The thruster design principle is to use in pairs, and position control is decoupled from attitude control. Since the thruster is unidirectional, each degree of freedom forms two directions. Therefore, the number of ducted thrusters 10 is 24, and each degree of freedom is controlled by two pairs of ducted thrusters 10. The specific layout is as follows:

[0068] The position of the three-degree-of-freedom rotating target is represented by the coordinate system oxyz, where o represents the origin, which is also the center of the ball bearing. x, y, and z are three coordinate axes parallel to the three-degree-of-freedom rotating target edges. The x and y axes are along the directions of the first and second balancing mechanisms, respectively. The 12 thrusters used for position control, 8 of which are arranged on the xoy (horizontal) plane, and the other 4 thrusters are arranged on the yoz or zox plane. The arrangement is as follows: Figure 5(a) to Figure 5(b) As shown, the direction of the thruster is drawn in the figure.

[0069] The ducted thrusters used for attitude control are used in pairs to form a couple. The direction of the couple needs to be parallel to the xoy, yoz, and zox planes. They can be installed on the top surface, and the arrangement direction is shown in Figure 5(c). 12 thrusters can be arranged at the four vertices of the top surface, with 3 at each corner. "×" indicates that the vertical plane is downward, and "·" indicates that the vertical plane is upward.

[0070] The air-floating ball bearing 13 can be realized in two ways.

[0071] The first implementation is shown in FIG3 . The air-floating ball bearing 13 comprises a hanging rope joint 15 , a convex ball air pipe joint 16 , a rotating concave ball 17 and a suspended convex ball 18 .

[0072] The suspension convex ball 18 is fixedly connected to the convex ball suspension wire joint 15, and the convex ball suspension wire joint 15 is a suspension connection end of the three-degree-of-freedom rotation target; the convex ball air pipe joint 16 is used to connect the suspension convex ball 18 and supply air to the suspension convex ball 18. The suspension convex ball 18 is provided with an air outlet hole, and air is discharged through the air outlet hole. An air floating lubrication layer is formed on the contact surface between the suspension convex ball 18 and the rotating concave ball 17, so that the suspension convex ball 18 and the rotating concave ball 17 can realize frictionless free rotation;

[0073] The rotating concave ball 17 is connected to the structural member of the three-degree-of-freedom rotating target through the concave ball flange 19.

[0074] In one embodiment of the present invention, the convex ball air pipe joint 16 and the convex ball suspension wire joint 15 are respectively the air supply end and the suspension connection end of the three-degree-of-freedom rotating target. Low-pressure air not higher than 0.8Mpa passes through the air outlet on the suspended convex ball 18, and forms an air-floating lubrication layer of about 10 microns on the contact surface between the suspended convex ball 18 and the rotating concave ball 17, so that the suspended convex ball 18 and the rotating concave ball 17 can achieve nearly frictionless free rotation. The rotating concave ball 17 is connected to the structural parts of the three-degree-of-freedom rotating target through the concave ball flange 19, realizing the three frictionless rotational degrees of freedom of the three-degree-of-freedom rotating target relative to the ball bearing, namely rolling, pitching and yaw. The three-degree-of-freedom rotating target 7 can rotate 360° around the vertical axis in the air-floating state, and can rotate not less than ±12° around the two horizontal axes.

[0075] The second implementation method is Figure 4 shown. Figure 4 and Figure 2 The difference is that the suspended ball bearing has a different structure. The air-floating ball bearing 13 includes a convex ball flange 20, a rotating convex ball 21, a suspended concave ball 22, a target box 23, a concave ball hanging wire joint 25, and a concave ball air path interface 24;

[0076] The concave ball hanging wire joint 25 and the concave ball air path interface 24 are fixed on the suspended concave ball 22, the convex ball flange 20 is fixedly installed with the rotating convex ball 21, and the rotating convex ball 21 is connected and fixed to the structural parts of the three-degree-of-freedom rotating target through the convex ball flange 20; the rotating convex ball 21 is located inside the suspended concave ball 22, and the gas is ejected from the suspended concave ball 22 to form an air-floating lubrication layer between the suspended concave ball 22 and the rotating convex ball 21; so that the suspended concave ball 22 and the convex ball flange 20 can achieve frictionless free rotation.

[0077] The first balancing mechanism 11 and the second balancing mechanism 14 are used to adjust the center of mass position of the six-degree-of-freedom target by moving the mass of the slider, so as to eventually balance the six-degree-of-freedom target in the x and y directions of the horizontal plane.

[0078] The closed-loop control system of the three-degree-of-freedom translation unit includes translation control of two axes and constant force tracking control of the vertical axis. The translation rail 2 and the telescopic cantilever 3 are used to control the two-dimensional position of the hanging wire by translation and telescoping in the guide rail direction and the vertical guide rail direction, respectively. The hanging wire inclination detection system 5 can simultaneously detect the inclination of the hanging wire in the guide rail direction and the vertical guide rail direction, that is, the hanging point and the target position have a deviation. At this time, the control computer calculates the control instruction based on the closed-loop feedback of the hanging wire inclination angle, and sends it to the translation rail 2 and the telescopic cantilever 3, and finally realizes the high-precision horizontal position tracking of the hanging wire. A constant force control method is adopted in the vertical direction. The constant force unloading hanging wire is connected to the three-degree-of-freedom rotating target 7, which can move up and down with the three-degree-of-freedom rotating target, and always maintains a constant unloading tension, which is used to realize the weightlessness simulation in the vertical direction.

[0079] In the closed-loop control system of the three-degree-of-freedom rotation unit, before control, the first balancing mechanism 11 and the second balancing mechanism 12 are used to complete the leveling of the center of mass of the platform according to the gyro signal to reduce the interference torque. During control, according to the measured results of the gyro attitude signal, the control program calculates the control amount and converts it into the thrust of the ducted fan, and sends instructions to the ducted thruster 10 to perform attitude stabilization control or maneuvering control.

[0080] The constant force unloading hanging wire is a connecting hanging wire for suspending a three-degree-of-freedom rotating target. The upper end is connected to the constant force unloading mechanism. The constant force control principle is adopted. The hanging wire can move freely in the vertical direction with the movement of the three-degree-of-freedom rotating target; the hanging wire inclination detection system 5 is used to detect the hanging wire inclination caused by the horizontal movement of the three-degree-of-freedom rotating target.

[0081] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A suspended six-degree-of-freedom spacecraft dynamics simulation device, wherein the six degrees of freedom include three degrees of freedom translation and three degrees of freedom rotation, wherein the three degrees of freedom translation is movement in two coordinate axes of the horizontal plane and in the vertical direction, and the three degrees of freedom rotation is rotation around two coordinate axes of the horizontal plane and in the vertical direction, characterized in that: It comprises a bracket (1), a translation guide rail (2), a telescopic cantilever (3), a hanging wire, a fixed pulley, a constant force unloading mechanism (4), a hanging wire inclination detection system (5), and a three-degree-of-freedom rotating target (7); A translation guide rail (2) is mounted on the bracket (1), is located on a horizontal plane, and can translate along a coordinate axis of the horizontal plane; The telescopic cantilever (3) has one end fixedly mounted on the translation guide rail (2). As the translation guide rail (2) moves horizontally, a fixed pulley is mounted on the other end, so that the telescopic cantilever can be extended and retracted along another coordinate axis direction on the horizontal plane. The two-dimensional movement of the telescopic cantilever on the horizontal plane enables the following of the two-dimensional movement of the unloading target on the horizontal plane. A hanging wire, one end of which is used to suspend the air-floating ball bearing of the three-degree-of-freedom rotating target (7), and the other end of which passes around a fixed pulley installed at one end of the telescopic cantilever (3), extends along the direction of the telescopic cantilever (3), and is connected to the constant force unloading mechanism (4); A three-degree-of-freedom rotating target (7) has an internal air-floating ball bearing mechanism, and a shell of the three-degree-of-freedom rotating target can freely rotate with three degrees of freedom around the center of the air-floating ball bearing; an air supply pipe (6) supplies air to the air-floating ball bearing mechanism; The constant force unloading mechanism (4) is installed on the telescopic cantilever (3), and adopts the constant force control principle to control the hanging wire to move freely in the vertical direction following the three-degree-of-freedom rotation target, and always maintains a constant unloading tension, thereby realizing weightlessness simulation in the vertical direction; A hanging wire inclination angle detection system (5) is used to detect the angle between the plane formed by the direction in which the hanging wire deviates from the translation guide rail (2) and the vertical direction, and the angle between the plane formed by the direction in which the hanging wire deviates from the vertical guide rail and the vertical direction; The control computer performs feedback closed-loop calculation based on the measurement results of the hanging wire inclination detection system (5), obtains motion control instructions, and drives the translation guide rail (2) and the telescopic cantilever (3) to move, so that the hanging wire maintains a constant vertical direction during the movement of the three-degree-of-freedom rotating target (7), thereby realizing horizontal position tracking of the three-degree-of-freedom rotating target (7).

2. A suspended six-degree-of-freedom spacecraft dynamics simulation device according to claim 1, characterized in that: The constant force unloading mechanism (4) comprises a roller, a motor, and a dynamometer; The motor is used to control the rotation of the drum; the hanging wire is fixed and wound on the drum; the dynamometer is used to measure the tension on the hanging wire and is used for constant force closed-loop feedback control of the constant force unloading mechanism.

3. A suspended six-degree-of-freedom spacecraft dynamics simulation device according to claim 1, characterized in that: The three-degree-of-freedom rotation target (7) comprises an air pipe interface (8), a hanging wire interface (9), a ducted thruster (10), a first balancing mechanism (11), an industrial computer (12), an air-floating ball bearing (13), a second balancing mechanism (14), an inertial measurement unit (26), and an air supply pipe (6); An air-floating ball bearing (13) enables a three-degree-of-freedom rotating target to perform three-degree-of-freedom rotation through air-floating lubrication; An air pipe interface (8) is used to supply air to the air-floating ball bearing (13) and is connected to the air supply pipe (6); A hanging wire interface (9), used for connecting the hanging wire; The ducted thruster (10) is an actuator in a three-degree-of-freedom rotating target, used to provide thrust to the target and control its translational position movement and rotational attitude; The first balancing mechanism (11) and the second balancing mechanism (14) are used to adjust the projection position of the mass center of the three-degree-of-freedom rotating target (7) on the horizontal plane; when the mass center coincides with the spherical center of the air-floating ball bearing (13), the three-degree-of-freedom rotating target after suspension completely eliminates the influence of gravity and can simulate the free rotation state on orbit; The industrial computer (12) is used to control the on / off state of each ducted thruster (10).

4. A suspended six-degree-of-freedom spacecraft dynamics simulation device according to claim 3, characterized in that: The ducted thruster (10) is a unidirectional thruster.

5. A suspended six-degree-of-freedom spacecraft dynamics simulation device according to claim 4, characterized in that: The number of the ducted thrusters (10) is 24, and each degree of freedom is controlled by two pairs of ducted thrusters (10).

6. The suspended six-degree-of-freedom spacecraft dynamics simulation device according to claim 1, characterized in that: The air-floating ball bearing (13) comprises a hanging rope joint (15), a convex ball air pipe joint (16), a rotating concave ball (17) and a suspended convex ball (18); The suspension convex ball (18) is fixedly connected to the convex ball suspension wire joint (15), and the convex ball suspension wire joint (15) is a suspension connection end of a three-degree-of-freedom rotation target; the convex ball air pipe joint (16) is used to connect the suspension convex ball (18) and to supply air to the suspension convex ball (18). An air outlet is provided on the suspension convex ball (18), and an air floating lubrication layer is formed on the contact surface between the suspension convex ball (18) and the rotating concave ball (17), so that the suspension convex ball (18) and the rotating concave ball (17) can realize frictionless free rotation; The rotating concave ball (17) is connected to a structural member of a three-degree-of-freedom rotating target via a concave ball flange (19).

7. The suspended six-degree-of-freedom spacecraft dynamics simulation device according to claim 1, characterized in that: The three-degree-of-freedom rotating target (7) can rotate 360° around the vertical direction in an air-floating state, and can rotate around the guide rail direction on the horizontal plane and the direction perpendicular to the guide rail.

8. The suspended six-degree-of-freedom spacecraft dynamics simulation device according to claim 1, characterized in that: The air-floating ball bearing (13) comprises a convex ball flange (20), a rotating convex ball (21), a suspended concave ball (22), a concave ball hanging thread joint (25), and a concave ball air path interface (24); The concave ball hanging thread joint (25) and the concave ball air path interface (24) are fixed on the suspended concave ball (22); the convex ball flange (20) is fixedly installed with the rotating convex ball (21); the rotating convex ball (21) is connected and fixed to the structural member of the three-degree-of-freedom rotating target through the convex ball flange (20); the rotating convex ball (21) is located inside the suspended concave ball (22); gas is ejected from the suspended concave ball (22) to form an air-floating lubrication layer between the suspended concave ball (22) and the rotating convex ball (21); so that the suspended concave ball (22) and the convex ball flange (20) can realize frictionless free rotation.

9. The suspended six-degree-of-freedom spacecraft dynamics simulation device according to claim 1, characterized in that: The first balancing mechanism (11) and the second balancing mechanism (14) adjust the center of mass position of the three-degree-of-freedom rotating target by moving the mass of the slider.

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