A six-DOF simulator for low-gravity landing buffer

Abstract

This invention provides a six-degree-of-freedom simulator for low-gravity landing cushioning, comprising a landing leg assembly, a frame, an IMU, an air-bearing ball bearing, and a connecting column forming an attitude control platform and a translational platform. Four landing leg assemblies are evenly arranged on the frame. An air-bearing ball bearing is located in the middle of the frame, with an IMU mounted above it. The lower part of the air-bearing ball bearing is connected to the translational platform via the connecting column. A control component is also provided on the frame, and the landing leg assemblies and IMU are connected to the control component. The planar air cushion of the translational platform is used for support on a simulated tilting platform, and the landing leg assemblies act on the simulated landing surface. This invention can record attitude changes and the force and torque values ​​of the landing legs during landing, and compare the experimental data with simulation results from a full-physics simulation test.

Description

Technical Field

[0001] This invention belongs to the field of landing tests, and in particular relates to a six-degree-of-freedom simulator for low-gravity landing buffer. Background Technology

[0002] Deep space probes and Earth-orbiting spacecraft share many similarities in environmental adaptability and testing considerations, but there are also differences. In deep space exploration, the gravitational acceleration of other celestial bodies differs from that of Earth, resulting in varying gravitational forces experienced by the probe upon landing. For example, the Moon's gravitational acceleration is only 1 / 6 that of Earth, and Mars' is 1 / 3. Therefore, to simulate the landing impact of a lunar lander on Earth's surface, a gravitational field with a gravitational acceleration of g / 6 must first be established.

[0003] For novel actively controlled landing legs, considering efficiency, schedule, and feasibility, ground verification tests at the whole-vehicle level are insufficient; single-unit landing leg tests are necessary beforehand. Landing in orbit has no degree of freedom limitations, and the load mass and inertia borne by the landing legs are at the whole-vehicle level. For single-unit ground verification tests to be sufficiently effective, it is necessary to simulate the degrees of freedom in orbit and the load mass and inertia borne. This necessitates the development of a six-degree-of-freedom simulator for low-gravity landing cushioning.

[0004] Currently available six-degree-of-freedom (6DOF) simulators are mostly used in microgravity environments such as space spin target capture and rendezvous / docking, but have not yet been used for landing cushioning of probe active legs in deep space exploration. Capture and rendezvous / docking experiments are fundamentally different from landing cushioning experiments, and the design concepts of six-DOF simulators are also very different. Patent CN112382160A introduces a six-DOF simulator air-floating pulley system. This invention relates to an air-floating pulley system that solves the problem that traditional simulators cannot meet the requirements of aerospace missions by providing six-degree-of-freedom omnidirectional three-dimensional space simulation. It mainly includes an upper frame assembly, a lower frame assembly, a mounting plate, multiple fixed pulleys, and ropes. It is suitable for low-speed mechanism motion, but its application is limited and cannot be used for landing leg simulation. Summary of the Invention

[0005] In view of this, the present invention aims to propose a six-degree-of-freedom simulator for low-gravity landing buffer, which solves the problem of conducting landing buffer tests on the active control landing legs of a new type of lunar probe through a test simulation system on the ground, while measuring the changes in attitude of the simulator during landing and the values ​​of the landing leg contact force and torque.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A six-DOF simulator for low-gravity landing cushioning includes a landing leg assembly, a frame, an IMU, air-bearing ball bearings, and a connecting column forming an attitude control platform and a translational platform.

[0008] Four landing leg assemblies are evenly arranged on the frame. An air-bearing ball bearing is provided in the middle of the frame. An IMU is provided above the air-bearing ball bearing. The lower part of the air-bearing ball is connected to the translation platform through a connecting column.

[0009] The frame is also equipped with a control component, and the landing leg assembly and IMU are connected to the control component.

[0010] The planar air cushion of the translational platform is used to support the simulated tilting platform, and the landing leg assembly is used to act on the simulated landing surface.

[0011] Furthermore, the landing leg assembly includes a landing leg body, an interface adapter, and a six-dimensional force sensor. The landing leg body is connected to the frame in sequence through the interface adapter and the six-dimensional force sensor.

[0012] Furthermore, the frame is square in shape, and the landing leg assemblies are respectively connected to the four corners of the frame.

[0013] Furthermore, a high-speed camera target is also provided on the air-bearing ball bearing.

[0014] Furthermore, the angle between the simulated tilting platform and the horizontal plane is 9.59°, and the angle between the simulated landing surface and the vertical plane is also 9.59°; the angle between the simulated tilting platform and the simulated landing surface is 90°.

[0015] Furthermore, the translational platform includes a constant force mechanism, a base, and a planar air cushion. The connecting column is connected to the constant force mechanism, and the bottom of the constant force mechanism is provided with a base, on which several planar air cushions are provided.

[0016] The connecting column and the constant force mechanism are connected by an electromagnet.

[0017] A method for using a six-DOF simulator for low-gravity landing buffering includes the following steps:

[0018] S1, Attitude control platform assembly;

[0019] S2. Assemble the IMU, high-speed camera target, and control components on the attitude control platform;

[0020] S3, Translational Platform Assembly;

[0021] S4. Connect the attitude control platform and the translation platform to form a simulator;

[0022] S5, equipped with a flat attitude control platform;

[0023] S6. Hoist the device to the simulated tilting platform for the experiment.

[0024] Compared with existing technologies, the six-degree-of-freedom simulator for low-gravity landing buffer described in this invention has the following advantages:

[0025] (1) The six-degree-of-freedom simulator for low-gravity landing buffer described in this invention adopts a combination of a probe body structure simulation component and a real landing leg to form a probe simulator. Its overall mass and inertia are consistent with the real probe, thereby achieving dynamic equivalence.

[0026] (2) The six-degree-of-freedom simulator for low-gravity landing buffer described in this invention includes an air-floating ball bearing, a constant force mechanism, and a planar thrust bearing, which can realize the release of 6 degrees of freedom and has very low friction loss, and can truly reflect the attitude change of the probe at the moment of landing.

[0027] (3) The six-degree-of-freedom simulator for low-gravity landing buffer described in this invention can record the changes in attitude and the values ​​of force and torque of the landing leg during the landing process, and compare the test data and simulation results through the full physical simulation test.

[0028] (4) The six-degree-of-freedom simulator for low-gravity landing buffer described in this invention uses a simulator platform for power supply and recording, without any external cables, and has minimal external interference.

[0029] (5) The six-degree-of-freedom simulator for low-gravity landing buffer described in this invention uses a six-degree-of-freedom simulator to conduct landing tests. When sliding on an inclined platform, it simulates the lunar gravity field in the direction of the normal to the landing surface. It has the characteristics of being able to conduct repeated landing tests, with no limit on the number of tests, simple test operation, short test interval, and high fidelity. Attached Figure Description

[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0031] Figure 1 This is a schematic diagram illustrating the simulation principle of a six-degree-of-freedom simulator for low-gravity landing buffer as described in an embodiment of the present invention.

[0032] Figure 2 This is a front view of a six-degree-of-freedom simulator for low-gravity landing buffering as described in an embodiment of the present invention;

[0033] Figure 3 This is a side view of a six-degree-of-freedom simulator for low-gravity landing buffering, as described in an embodiment of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] 1. Landing legs; 2. Interface adapter; 3. Six-dimensional force sensor; 4. Frame; 5. IMU; 6. High-speed camera target; 7. Controller assembly; 8. Air-bearing ball bearing; 9. Connecting column; 10. Electromagnet; 11. Constant force mechanism; 12. Base; 13. Planar air cushion; 14. Protective support; 15. Counterweight. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] For the landing cushioning of the actively controlled landing legs of the new lunar probe, ground-based experimental simulation systems are required for verification. The simulator must allow for the release of all six degrees of freedom during landing, with the three rotational degrees of freedom operating within ±30° without interference. Mass characteristics, including mass, inertia, and center of mass position, must be consistent with the on-orbit probe. To ensure accuracy, ground-based verification tests should minimize interference from external factors. Simultaneously, the ground-based verification tests need to measure the attitude changes of the simulator during landing and the contact force and torque of landing leg 1. Therefore, the following simulator was used to complete the test.

[0041] A six-DOF simulator for low-gravity landing buffering includes an attitude control platform and a translational platform consisting of landing leg components 1, a frame 4, an IMU 5, air-bearing ball bearings 8, and connecting columns 9. The translational platform achieves mass characteristics consistent with the on-orbit probe's state; six degrees of freedom of motion are released, with a rotational degree of freedom range greater than ±30°; to avoid the influence of external factors, the simulator has no external cables except for the air supply pipeline; during landing, data on attitude changes, forces, and torques can be recorded.

[0042] Four landing leg assemblies 1 are evenly arranged on the frame 4. An air-bearing ball bearing 8 is provided in the middle of the frame 4. An IMU 5 is provided on the upper part of the air-bearing ball bearing 8. The lower part of the air-bearing ball is connected to the translation platform through a connecting column 9.

[0043] Landing Leg 1 is the mechanism for the probe to land. It is an active control leg for soft landing and also serves as the target of a six-degree-of-freedom simulator for low-gravity landing buffering. Its main purpose is to verify the landing performance and control parameters of Landing Leg 1.

[0044] The frame 4 is also equipped with a control component, which includes a test controller, an industrial computer, a sensor amplifier, a power supply, etc. The landing leg 1 assembly and IMU5 are connected to the control component. The IMU5 is installed on the upper end of the air-bearing ball bearing 8 to measure the angle, angular velocity and linear acceleration during the landing process. The controller assembly 7 ensures the landing control of the landing leg 1 and the power supply to the attitude control platform. Since it is used for low gravity landing tests, the overall strength and rigidity of the attitude control platform need to be designed to be guaranteed.

[0045] The planar air cushion 13 of the translational platform is used to support the simulated tilting platform, and the landing leg 1 assembly is used to act on the simulated landing surface.

[0046] The attitude control platform achieves rotational degrees of freedom in three directions for the simulator. The design of the air-bearing ball bearing 8 and the attitude control platform frame 4 considers interference issues, ensuring rotational angles greater than ±30° in all three directions. Simultaneously, the rotational inertia of the attitude control platform needs to be simulated. Therefore, in the design of the electrical components of the attitude control platform, the air-bearing ball bearing 8 is used as the center, and electrical components and counterweights 15 are placed at corresponding positions to achieve the target inertia.

[0047] Preferably, the landing leg 1 component includes a landing leg 1 body, an interface adapter 2, and a six-dimensional force sensor 3. The landing leg 1 body is connected to the frame 4 in sequence through the interface adapter 2 and the six-dimensional force sensor 3. The six-dimensional force sensor 3 is installed between the landing leg 1 and the interface adapter 2 to measure the force and torque acting on the landing leg 1 during the landing process.

[0048] Preferably, the frame 4 is square in shape, and the landing leg 1 components are respectively connected to the four corners of the frame 4.

[0049] Preferably, the air-bearing ball bearing 8 is also provided with a high-speed camera target.

[0050] Preferably, the angle between the simulated tilting platform and the horizontal plane is 9.59°, and the angle between the simulated landing surface and the vertical plane is also 9.59°; the angle between the simulated tilting platform and the simulated landing surface is 90°; when the angle between the landing surface normal and the horizontal plane is 90°, the gravity component of the simulator in the normal direction of the landing surface is exactly the gravity of the lunar landing; when the angle is 9.59°, the lunar gravity field is simulated in the normal direction of the landing surface.

[0051] Preferably, the translational platform includes a constant force mechanism 11, a base 12 and a planar air cushion 13. The connecting column 9 is connected to the constant force mechanism 11. The bottom of the constant force mechanism 11 is provided with a base 12, and a plurality of planar air cushions 13 are provided on the base 12.

[0052] The translational platform achieves translational degrees of freedom in three directions. The vertical degree of freedom is achieved by a constant force mechanism 11, which provides constant force support within a stroke of ±100mm. The planar translational degree of freedom is achieved by a planar air cushion 13 sliding on the platform. The translational platform moves along the platform together with the attitude control platform; therefore, the overall mass of the translational platform and the attitude control platform simulates the total mass of the detector.

[0053] The connecting column 9 and the constant force mechanism 11 are connected by an electromagnet 10.

[0054] Preferably, the frame 4 is provided with a counterweight 15, and a support protection is provided on one side of the landing surface.

[0055] A method for using a six-DOF simulator for low-gravity landing buffering includes the following steps:

[0056] S1. Attitude control platform assembly: After all parts of the system are assembled, the attitude control platform is assembled. The frame 4 is fixed and the frame 4 is assembled with the air-bearing ball bearing 8. Then, the various interfaces of the landing leg 1 component are assembled. The interface adapter 2 is assembled with the six-dimensional force sensor 3. After the component is assembled, it is assembled with the frame 4. After the interface and air-bearing ball bearing 8 are assembled, this part is precisely measured and adjusted to ensure the relative position of the interfaces inside the simulator.

[0057] S2. Assemble the IMU5, high-speed camera target, and control components on the attitude control platform; after fine-tuning, assemble the landing leg 1 component; after the landing leg 1 component is assembled, perform fine measurement on the positional relationship between the landing leg 1 components; assemble the IMU5, high-speed camera target 6, and controller component 7.

[0058] S3. Assembly of the translation platform; After the attitude control platform is assembled, the translation platform is assembled. First, the constant force mechanism 11 is adjusted to a constant force under the target weight. The constant force mechanism 11 is connected to the base 12. Then, the connecting column 9 is assembled with the constant force mechanism 11. The electromagnet 10 is assembled on the column. Finally, the translation platform is lifted up and four flat air cushions 13 are installed under the base 12. The translation platform assembly is completed.

[0059] S4. Connect the attitude control platform and the translation platform to form a simulator; place the translation platform on the ground, protect the flat air cushion 13 to prevent scratching the surface, and then hoist the attitude control platform onto the translation platform. Weigh and record the weight during the hoisting process. The total weight of the translation platform and the attitude control platform is the weight of the detector simulator.

[0060] S5. Balancing the attitude control platform: After the translation platform and the attitude control platform are assembled, the attitude control platform is balanced to keep the attitude control platform in balance relative to the air float bearing 8. By adding or subtracting counterweight 15 on the attitude control platform based on the total weight of the translation platform and the attitude control platform, the attitude control platform is balanced.

[0061] S6. Hoist to the simulated inclined platform for testing; after the overall assembly is completed, hoist to the inclined platform for landing buffer test.

[0062] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A six-degree-of-freedom simulator for low-gravity landing buffering, characterized in that: The attitude control platform and translational platform consist of landing leg components, frame, IMU, air-bearing ball bearings, and connecting columns. Four landing leg assemblies are evenly arranged on the frame. An air-bearing ball bearing is provided in the middle of the frame. An IMU is provided above the air-bearing ball bearing. The lower part of the air-bearing ball is connected to the translation platform through a connecting column. The frame is also equipped with a control component, and the landing leg assembly and IMU are connected to the control component. The planar air cushion of the translational platform is used to support the simulated inclined platform, and the landing leg assembly is used to act on the simulated landing surface; The landing leg assembly includes a landing leg body, an interface adapter, and a six-dimensional force sensor. The landing leg body is connected to the frame in sequence through the interface adapter and the six-dimensional force sensor. The frame is square in shape, and the landing leg assemblies are connected to the four corners of the frame respectively; The landing leg assembly includes a landing leg body, an interface adapter, and a six-dimensional force sensor. The landing leg body is connected to the frame in sequence through the interface adapter and the six-dimensional force sensor. The six-dimensional force sensor is installed between the landing leg and the interface adapter to measure the forces and torques acting on the landing leg during the landing process. The angle between the simulated tilting platform and the horizontal plane is 9.59°, and the angle between the simulated landing surface and the vertical plane is also 9.59°; the angle between the simulated tilting platform and the simulated landing surface is 90°.

2. A six-degree-of-freedom simulator for low-gravity landing buffering according to claim 1, characterized in that: The air-bearing ball bearing is also equipped with a high-speed camera target.

3. A six-degree-of-freedom simulator for low-gravity landing buffering according to claim 1, characterized in that: The translational platform includes a constant force mechanism, a base, and a planar air cushion. The connecting column is connected to the constant force mechanism. The bottom of the constant force mechanism is provided with a base, and the base is provided with several planar air cushions. An electromagnet is provided on the connecting column.

4. A method of using a six-degree-of-freedom simulator for low-gravity landing buffer as described in any one of claims 1-3, characterized in that: Includes the following steps: S1, Attitude control platform assembly; S2. Assemble the IMU, high-speed camera target, and control components on the attitude control platform; S3, Translational Platform Assembly; S4. Connect the attitude control platform and the translation platform to form a simulator; S5, equipped with a flat attitude control platform; S6. Hoist the device to the simulated tilting platform for the experiment.

Images