Drag-free spacecraft ground experiment system for gravitational wave detection task

Abstract

The invention discloses a drag-free spacecraft ground experiment system for a gravitational wave detection task, and belongs to the technical field of spacecraft dynamics and control, and the drag-free spacecraft ground experiment system comprises a smooth flat platform, a non-contact real-time position attitude measurement system and a drag-free spacecraft simulator; the non-dragging spacecraft simulator is located on a smooth flat platform and simulates a microgravity environment; the smooth and flat platform provides a friction-free and flat plane, and is preferably a smooth granite platform; the non-contact real-time position and attitude measurement system is used for measuring position and attitude information of the drag-free spacecraft simulator and the two test masses in real time, and sending the position and attitude information to the airborne calculation module of the drag-free spacecraft ground simulator through the wireless information transmission system; when the system is applied to a ground experiment, the problem that complex dynamic coupling and control between a drag-free spacecraft and a test mass cannot be simulated in the ground experiment can be solved; and the system provided by the invention has a higher degree of freedom.

Description

Technical Field

[0001] The present invention belongs to the field of spacecraft dynamics and control technology, and in particular relates to a drag-free spacecraft ground experiment system for gravitational wave detection missions. Background Art

[0002] The gravitational wave detection mission is an important research field in modern physics and astronomy. In order to detect weak gravitational wave signals in space, multiple drag-free spacecraft are needed. The drag-free control technology uses micro-thrusters to compensate for the non-conservative forces on the spacecraft so that it follows the movement of the test mass, thereby obtaining an ultra-low microgravity horizontal satellite platform, which can provide an ultra-low interference environment for scientific experiments. Space gravitational wave detection takes advantage of the large baseline of the drag-free satellite formation and can effectively realize gravitational wave detection in the millihertz band.

[0003] At present, there are many studies on satellite simulator formation ground experiment technology and ground semi-physical simulation of proof mass. However, there is no public information on the ground experiment system that combines the proof mass with the attitude of the no-drag spacecraft for experiment. It is impossible to effectively verify the dynamic coupling effect and control of the no-drag spacecraft and the proof mass. There is a strong coupling relationship between the proof mass and the no-drag spacecraft, so it is urgent to experimentally verify the above coupling relationship in ground experiments. Summary of the invention

[0004] The present invention proposes a drag-free spacecraft ground experiment system for gravitational wave detection missions. The system is applied to ground experiments to solve the problem that the complex dynamic coupling and control between the drag-free spacecraft and the test mass cannot be simulated in ground experiments. Through the system, dynamic simulation of multi-degree-of-freedom coupling of the drag-free spacecraft can be carried out under ground conditions, and the control method can be verified, providing technical support for future gravitational wave detection missions.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions: A drag-free spacecraft ground experiment system for a gravitational wave detection mission comprises a smooth and flat platform, a contactless real-time position and attitude measurement system, and a drag-free spacecraft simulator; the drag-free spacecraft simulator is located on the smooth and flat platform to simulate a microgravity environment; The smooth flat platform provides a frictionless, flat surface, preferably a smooth granite platform; The contactless real-time position and attitude measurement system is used to measure the position and attitude information of the drag-free spacecraft simulator and two proof masses in real time, and transmit it to the onboard computing module of the drag-free spacecraft ground simulator through a wireless information transmission system, preferably a real-time motion capture camera system; The hardware part of the drag-free spacecraft simulator includes a mechanical subsystem, an electrical subsystem, a gas path subsystem, and a drag-free subsystem; The mechanical subsystem provides overall structural support for the simulator, and simulator components are all installed and placed in the mechanical subsystem. Preferably, the mechanical subsystem is made of aviation aluminum alloy; The electrical subsystem includes a battery, a transformer, a voltage stabilizer, an airborne computing module, a signal conversion module, a relay module, a solenoid valve module, a wireless communication module, an electrical connection device, and a screen; the battery, transformer, and voltage stabilizer provide suitable and stable power supply for different devices; the recording computing module can receive the position and attitude information provided by the contactless real-time position and attitude measurement system through the wireless communication module, and provide the control instructions required for controlling the simulator and inspecting the quality in a programmable manner; the signal conversion module can convert the control instructions issued by the airborne computing module into relay switch signals; the relay module includes a multi-channel relay circuit, which can control the on-off of the solenoid valve module; the solenoid valve module receives the switch signal to control the on-off of the gas circuit; The gas circuit subsystem includes a gas cylinder, a first-level pressure reducing valve, a second-level filtering pressure reducing valve, a third-level high-precision pressure reducing valve, an air floating bearing, an air pipe, and a nozzle; the gas cylinder can store compressed gas for supplying gas to the nozzle and the air floating bearing; the first-level pressure reducing valve, the second-level filtering pressure reducing valve, and the third-level high-precision pressure reducing valve can adjust the gas pressure and filter impurities in the gas; the air floating bearing is used to maintain the free floating state of the simulator on a smooth and flat platform; the nozzle can spray compressed gas to adjust the position and posture of the simulator. Preferably, the nozzle includes a Laval nozzle.

[0006] The drag-free subsystem includes a test mass with an extension structure, an air bearing, and a test mass actuator; the test mass with an extension structure is a cubic test mass with extended extension structures on both sides, and the extension structures can be used as actuation points of the actuation force of the test mass actuator; the air bearing is used to achieve secondary suspension of the test mass and simulate the microgravity environment of the test mass. The test mass actuator is used to control the position and posture of the test mass, and preferably, the test mass actuator is a nozzle.

[0007] Beneficial effects: The present invention provides a drag-free spacecraft ground experiment system for gravitational wave detection missions, which has the following advantages over the prior art: 1. Compared with the existing ground experiment system without towing spacecraft, the system of the present invention has higher degrees of freedom. The system has nine degrees of freedom, including three degrees of freedom of the simulator body (translation and rotation in the horizontal plane) and six degrees of freedom of the two test masses (translation and rotation in the horizontal plane); 2. It can be used to verify the dynamic coupling between the drag-free spacecraft and the test mass, and complete the engineering principle verification of the drag-free spacecraft; 3. The drag-free spacecraft simulator of the present invention adopts a layered and looped layout with a clear structure, which facilitates the construction and assembly of the simulator and the replacement and maintenance of parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram of a ground experiment system for a drag-free spacecraft for a gravitational wave detection mission in an embodiment of the present invention; Figure 2 It is an assembly diagram of a towless spacecraft simulator in an embodiment of the present invention; Figure 3 A schematic diagram of the structure of each layer in the drag-free spacecraft simulator in an embodiment of the present invention; Figure 4 It is a schematic diagram of gas path connection in a towless spacecraft simulator according to an embodiment of the present invention; Figure 5 A schematic diagram of signal connection transmission in a towless spacecraft simulator according to an embodiment of the present invention; In the figure: 100 - smooth and flat platform; 200 - non-contact real-time position and attitude measurement system; 300 - drag-free spacecraft simulator; 1-air bearing a; 2-bottom plate; 3-first-level support column; 4-gas cylinder fixing part; 5-second-level filter pressure reducing valve; 6-third-level high-precision pressure reducing valve; 7-gas cylinder; 8-position control nozzle; 9-middle bottom plate; 10-second-level support column; 11-solenoid valve module; 12-high-precision position control nozzle; 13-signal conversion module; 14-relay module; 15-onboard computing module; 16-screen; 17-battery; 18-middle top plate; 19-third-level support; 20-inspection mass actuator; 21-air bearing b; 22-inspection mass with extended structure; 23-third-level high-precision pressure reducing valve fixing part; 24-top plate; 25-second-level filter pressure reducing valve fixing part; 26-first-level pressure reducing valve. DETAILED DESCRIPTION

[0009] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments: like Figure 1 As shown, the drag-free spacecraft ground experiment system of the present invention includes a smooth and flat platform 100, a contactless real-time position and attitude measurement system 200, and a drag-free spacecraft simulator 300; the smooth and flat platform 100 provides a basic plane for the movement of the drag-free spacecraft simulator 300, and an air bearing a1 is installed at the bottom of the drag-free spacecraft simulator 300, which contacts the smooth and flat platform 100 through the air bearing 1, and the gas cylinder 7 provides compressed gas to the air bearing a1, so that a layer of air film is formed between the air bearing a1 and the smooth and flat platform 100, thereby simulating a microgravity environment.

[0010] The contactless real-time position and attitude measurement system 200 measures the real-time position and attitude information of the drag-free spacecraft simulator 300 and the inspection mass 22 with an extended structure in real time, and sends it to the onboard computing module 15 through a wireless transmission system.

[0011] like Figure 2 As shown, the drag-free spacecraft simulator 300 includes: a bottom plate 2 that provides bottom support for the gas cylinder 7, a gas cylinder fixing member 4 is fixed on the bottom plate 2, and constitutes a side support for the gas cylinder 7; a primary support column 3 connects the bottom plate 2 and the middle bottom plate 9; a secondary filter pressure reducing valve 5, a position control nozzle 8, a solenoid valve module 11, a signal conversion module 13, a relay module 14, and a secondary pressure reducing filter valve fixing member 25 are all fixed on the middle bottom plate; one end of the third-level high-precision fixing member 23 is installed under the middle bottom plate 9, and the other end is connected to the third-level high-precision pressure reducing valve 6; the secondary support 10 is connected to the middle bottom plate Plate 9 and the middle top plate 18; the high-precision posture control nozzle 12 is fixed below the middle top plate 18, and the recording calculation module 15, screen 16, and battery 17 are fixed above the middle top plate 18; the three-level support 19 connects the middle top plate 18 and the top plate 24; the inspection mass actuator 20 and the air bearing b21 are installed on the top plate 24; the inspection mass 22 with an extended structure floats on the air bearing b21; the top plate 24 and the inspection mass 22 with an extended structure are reserved with mounting holes for positioning objects such as fluorescent marking points used by the contactless real-time position and posture measurement system 200.

[0012] The gas cylinder 7 is connected to the first-level pressure reducing valve 26 through the gas circuit interface, and the first-level pressure reducing valve 26 is connected to the second-level filter pressure reducing valve 5 through the gas pipe; the second-level filter pressure reducing valve 5 is divided into four ways through the gas pipe and respectively connected to the air floating bearing a1, two three-level high-precision filter valves 6, and the solenoid valve module 11; further, the solenoid valve module 11 is divided into two ways through the gas pipe and connected to the posture control nozzle 8 and the high-precision posture control nozzle 12; one three-level high-precision filter valve 6 is connected to the air floating bearing b21 through the gas pipe, and the other three-level high-precision filter valve 6 is connected to the solenoid valve module 11 through the gas pipe, and the solenoid valve module 11 is connected to the inspection quality actuator 20 through the gas pipe.

[0013] After passing through the transformer and the voltage stabilizer, the power supply 17 is respectively connected to the onboard computing module 15, the solenoid valve module 11, and the relay module 14 through wires; further, the onboard computing module 15 is connected to the signal conversion module 13 and the screen 16 through a signal line, the signal conversion module 13 is connected to the relay module 14 through a wire, and the relay module 14 is connected to the solenoid valve module 11 through a wire.

[0014] The inspection mass 22 with an extended structure is a cubic inspection mass with extended extended structures on both sides. The extended structure can be used as an actuation point for the actuating force of the inspection mass actuator 20. The inspection mass 22 with an extended structure realizes a microgravity environment through an air bearing b21. The inspection mass actuator 20 can perform displacement control and posture control on the inspection mass 22 with an extended structure perpendicular to the direction of the extended structure.

[0015] The working steps of the above experimental system are: 1. Confirm that the power supply 17 has sufficient power and the gas cylinder 7 has sufficient gas; 2. Confirm that the onboard computing module 15 is correctly connected to the signal conversion module 13 and the relay module 14, and can drive the solenoid valve module 11 to switch on and off normally; 3. Confirm that the non-contact real-time position and attitude measurement system 200 can send correct position information and attitude information, and confirm that the onboard computing module 15 can receive the position and attitude information; 4. The onboard computing module 15 issues control signals of the drag-free spacecraft simulator 300 and the inspection mass 22 with an extended structure to the signal conversion module 13 and the relay module 14, and finally controls the attitude control nozzle 8, the high-precision attitude control nozzle 12, and the inspection mass actuator 20 by controlling the on and off of the solenoid valve 11; 5. In the no-drag mode, the no-drag spacecraft simulator 300 tracks the relative displacement of the two test masses 22 with extended structures in the direction of the extended structures (corresponding to the displacement in the direction of the sensitive axis, performing no-drag control), and the test mass actuator 20 controls the displacement and attitude perpendicular to the direction of the extended structures (corresponding to electrostatic suspension control); 6. The onboard computing module 15 automatically records the position and attitude history information and the control signal history information.

[0016] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A drag-free spacecraft ground experiment system for gravitational wave detection mission, characterized in that: It includes a smooth and flat platform, a non-contact real-time position and attitude measurement system, and a drag-free spacecraft simulator; the drag-free spacecraft simulator is located on the smooth and flat platform to simulate a microgravity environment; the non-contact real-time position and attitude measurement system measures the position and attitude information of the drag-free spacecraft simulator and the inspection mass in real time, and sends it to the drag-free spacecraft ground simulator through a wireless information transmission system.

2. The drag-free spacecraft ground experiment system for gravitational wave detection mission according to claim 1, characterized in that: The drag-free spacecraft simulator includes a mechanical subsystem, an electrical subsystem, a pneumatic subsystem, and a drag-free subsystem; the mechanical subsystem provides overall structural support for the simulator, and simulator components are all installed in the mechanical subsystem; the electrical subsystem receives transmission signals and controls the mechanical subsystem and the pneumatic subsystem; the pneumatic subsystem provides conditions for simulating a microgravity environment; the drag-free subsystem includes a test mass with an extended structure, an air bearing, and a test mass actuator; The test mass with extension structure is a cubic test mass with extension structures on both sides, and the extension structures can be used as the actuation points of the actuation force of the test mass actuator; the air bearing is used to achieve secondary suspension of the test mass and simulate the microgravity environment of the test mass; The proof mass actuator is used to control the position and attitude of the proof mass.

3. The drag-free spacecraft ground experiment system for gravitational wave detection mission according to claim 2, characterized in that: The mechanical subsystem of the drag-free spacecraft simulator is divided into multiple layers. An air bearing is installed under the bottom plate of the lowest layer, which contacts the smooth and flat platform through the air bearing to simulate the microgravity environment. The bottom plates of each layer are connected by support columns to form a space for installing various components of the simulator.

4. The drag-free spacecraft ground experiment system for gravitational wave detection mission according to claim 2 or 3, characterized in that: The air path subsystem of the drag-free spacecraft simulator includes: a gas cylinder is connected to a first-level pressure reducing valve through an air path interface, and the first-level pressure reducing valve is connected to a second-level filter pressure reducing valve through an air pipe; the second-level filter pressure reducing valve is divided into four paths through an air pipe and respectively connected to an air bearing a, two three-level high-precision filter valves, and an electromagnetic valve module; the electromagnetic valve module is divided into two paths through an air pipe and connected to a posture control nozzle and a high-precision posture control nozzle; a three-level high-precision filter valve is connected to an air bearing b through an air pipe, and another three-level high-precision filter valve is connected to the electromagnetic valve module through an air pipe, and the electromagnetic valve module is connected to a test mass actuator through an air pipe.

5. The drag-free spacecraft ground experiment system for gravitational wave detection mission according to claim 4, characterized in that: The gas cylinder is installed on the bottom plate, and the gas cylinder fixing part is fixed on the bottom bottom plate to form the side support of the gas cylinder; the first-level support column connects the bottom plate and the middle bottom plate; the second-level filter pressure reducing valve, the posture control nozzle, the solenoid valve module, the signal conversion module, the relay module, and the second-level pressure reducing filter valve fixing part are all fixed on the middle bottom plate; one end of the third-level high-precision pressure reducing valve fixing part is installed under the middle bottom plate, and the other end is connected to the third-level high-precision pressure reducing valve; the second-level support connects the middle bottom plate and the middle top plate; the posture control nozzle is fixed under the middle top plate.

6. The drag-free spacecraft ground experiment system for gravitational wave detection mission according to claim 5, characterized in that: The top plate and the inspection mass with the extended structure are provided with mounting holes for positioning objects such as fluorescent marking points used by the non-contact real-time position and posture measurement system.

7. The drag-free spacecraft ground experiment system for gravitational wave detection mission according to claim 2 or 3, characterized in that: The electrical subsystem includes: after the power supply passes through the transformer and the voltage stabilizer, it is connected to the airborne computing module, the solenoid valve module, and the relay module through wires; the airborne computing module is connected to the signal conversion module and the screen through a signal line, the signal conversion module is connected to the relay module through a wire, and the relay module is connected to the solenoid valve module through a wire.

8. The drag-free spacecraft ground experiment system for gravitational wave detection mission according to claim 7, characterized in that: The computing module, screen, and battery are fixed on the middle top plate.

9. The drag-free spacecraft ground experiment system for gravitational wave detection mission according to claim 2 or 3, characterized in that: The drag-free subsystem includes a test mass with an extension structure, an air bearing b, and a test mass actuator; the test mass with an extension structure is a cubic test mass with extended extension structures on both sides, the extended structure serves as the actuation point of the actuating force of the test mass actuator, the test mass with an extension structure realizes a microgravity environment through the air bearing b, and the test mass actuator performs displacement control and attitude control on the test mass with an extension structure perpendicular to the direction of the extension structure.

10. The drag-free spacecraft ground experiment system for gravitational wave detection mission according to claim 9, characterized in that: The inspection mass actuator and the air bearing b are installed on the top layer; the inspection mass with the extended structure floats on the air bearing b.

Images