A satellite platform system for gravitational wave semi-physical experiments and its control method

Abstract

The present invention discloses a satellite platform system for semi-physical gravitational wave experiments and its control method. The system comprises a dynamics simulation system, a self-gravity regulation system, a drag-free motion simulation platform, and a satellite platform. The dynamics simulation system is located outside a vacuum chamber, while the self-gravity regulation system, the drag-free motion simulation platform, and the satellite platform are located inside. The system enables high-precision temperature control, magnetic field measurement, self-gravity regulation, and multi-degree-of-freedom drag-free control. It simulates the on-orbit operation of a satellite and can perform coupling experiments between inertial sensors and the satellite platform, as well as between a laser interferometry system and the satellite platform. This system provides an ultra-clean, ultra-precise, and ultra-stable satellite experimental platform for detecting gravitational waves in space, significantly reducing the risk and cost of detection.

Description

Technical Field

[0001] The present invention relates to the field of space gravitational waves, and in particular to a satellite platform system for gravitational wave semi-physical experiments and a control method thereof. Background Art

[0002] To achieve high system sensitivity during space gravitational wave detection, it is necessary to overcome the influence of the satellite platform on payload measurement results. Therefore, it is necessary to design a satellite platform that is ultra-clean, ultra-precise, and ultra-stable. Considering that the coupling between subsystems in a space gravitational wave detection system, such as the coupling between inertial sensors and the satellite platform, the coupling between the laser interferometry system and the satellite platform, and the coupling between inertial sensors and the laser interferometry system, far exceeds that of traditional spacecraft systems, the influence of subsystem coupling, which is negligible in traditional spacecraft systems, must be considered in the simulation of space gravitational wave detection systems. To ensure the smooth implementation of space gravitational wave detection missions and reduce mission costs and risks, it is necessary to conduct targeted research on semi-physical simulation satellite platforms suitable for space gravitational wave detection systems. Existing semi-physical experiments for space gravitational wave detection mainly focus on satellite constellation establishment, drag-free control system design and simulation, and semi-physical payload experimental verification. However, there is no design of a satellite platform specifically designed for ground-based semi-physical experiments for space gravitational wave detection missions.

[0003] The space-based gravitational wave detection mission places unprecedented, ultra-high precision demands on the accuracy of laser interferometry between space gravitational wave detectors, attitude and pointing control, residual acceleration noise of the test mass, and temperature control accuracy within critical payload regions. This makes it impossible to directly apply the physical-in-the-loop simulation techniques used for traditional spacecraft systems to these space-based gravitational wave detection system experiments. Currently, there is considerable research on ground-based physical-in-the-loop simulation of distributed satellite system dynamics and control, as well as ground-based physical-in-the-loop simulation of test mass. However, a ground-based physical-in-the-loop simulation platform for space gravitational wave detector systems that integrates test mass, formation satellite attitude, formation satellite orbit control, and laser link control is still lacking. Therefore, it is necessary to design a ground-equivalent, ultra-clean, ultra-precise, and ultra-stable physical-in-the-loop experimental satellite platform to verify the coupling effects between subsystems. Summary of the Invention

[0004] The object of the present invention is to provide a satellite platform system and a system control method for gravitational wave semi-physical experiments to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned objectives, the first aspect of the present invention provides a satellite platform system for semi-physical experiments of gravitational waves, comprising a dynamics simulation system, a self-gravity regulation system, a drag-free motion simulation platform, and a satellite platform, wherein the dynamics simulation system is located outside a vacuum tank, and the self-gravity regulation system, the drag-free motion simulation platform, and the satellite platform are located inside the vacuum tank;

[0006] The dynamics simulation system includes an attitude and orbit control dynamics simulator and an attitude and orbit control stand-alone interface simulator. These are used to output high-precision satellite attitude and orbit information in real time, and take into account the coupling between systems, including the coupling between the satellite platform and the proof mass, the coupling between the satellite platform and the interferometric measurement system, and the coupling between the proof mass and the interferometric measurement system.

[0007] The self-gravitation adjustment system is a set of wide-guide rail self-gravitation adjustment components that uses a stepper motor to move the mass block to the appropriate position, and can provide nanometer-level adjustable self-gravitation.

[0008] The drag-free motion simulation platform is constructed with six-degree-of-freedom piezoelectric ceramics to simulate the frictionless translation in two linear directions and three-degree-of-freedom rotation in the horizontal plane of the orbiting satellite, a total of five degrees of freedom, and to offset the influence of gravity on the satellite platform.

[0009] The satellite platform integrates a magnetic field measurement system, a high-precision temperature control system, a drag-free payload computer and a core module to achieve magnetic field measurement and temperature control of the core module and drag-free control of the satellite.

[0010] Furthermore, the satellite platform includes a magnetic field measurement system, a high-precision temperature control system, a drag-free payload computer, and a core module;

[0011] The magnetic field measurement system is used to collect magnetic field information of the core module and deduct magnetic field and fluctuation interference from the model during subsequent data processing and analysis;

[0012] The high-precision temperature control system is used to control the core module temperature within the required range for the payload. It adopts a combination of active and passive methods: active temperature control utilizes a high-precision temperature controller to achieve preliminary suppression of complex external thermal disturbances; passive temperature control adopts a multi-stage thermal damping method and achieves mK-level control of key components by constructing a low-pass filter for thermal noise.

[0013] The drag-free load computer is the physical platform for the operation of the drag-free control algorithm, providing software and hardware support for the implementation of the drag-free control algorithm;

[0014] The core module is an independently designed structure used for the integrated installation of the main payload, which includes high-precision inertial sensors, optical reference plates, and primary and secondary mirrors.

[0015] Furthermore, the magnetic field measurement system consists of several magnetometers and supporting brackets. Several ground magnetometers are arranged in each satellite core module, a ground magnetometer A is arranged outside each satellite module and inside the vacuum tank, and a ground magnetometer B is arranged far away from the vacuum tank to monitor the errors caused by the magnetic induction of the vacuum tank and the fluctuation of the geomagnetic field to the magnetometer in the cabin.

[0016] Furthermore, the high-precision temperature control system consists of a platinum resistance temperature measurement module and a system management and control module, and uses a PID algorithm to achieve precise temperature control, so that the temperature acquisition value is controlled within the range of ±0.1°C of the set value.

[0017] Furthermore, the dragless payload computer includes a hardware platform development board, a Linux operating system, and payload management software: the hardware platform development board is used to verify the function of the processor; the Linux operating system is used to meet complex multi-interface communication requirements; the payload management software uses a multi-core design to manage computer peripherals and on-board single-machine devices to achieve high-freedom timing manipulation.

[0018] Furthermore, the main load is arranged at the inner center of the core module. The core module body uses lightweight materials to form a closed temperature-controlled space, and the outside is connected to the main structure of the platform module through multi-point insulation.

[0019] Furthermore, a multi-stage thermal control design is used inside and outside the core module panels to ensure high-precision internal temperature control.

[0020] Furthermore, the core module includes inertial sensors, laser interferometers, and a torsion balance interface for suspending the inertial sensors;

[0021] The laser interferometer includes an optical signal delay unit and a wavefront simulation unit, which are used to simulate the time and space problems caused by a delay of millions of kilometers in space;

[0022] The inertial sensor includes a suspended test mass block and a capacitive sensing and electrostatic drive system, which is used to measure the displacement of the test mass block relative to the satellite body as the input of the displacement drag-free controller.

[0023] Furthermore, the electrostatic drive system serves as an actuator of the suspension controller to control the relative position of other degrees of freedom of the test mass block with respect to the satellite body.

[0024] Another aspect of the present invention provides a satellite platform system control method for a gravitational wave semi-physical experiment, comprising the following steps:

[0025] Step 1: The laser interferometer measures the displacement between the two satellites, and the inertial sensor measures the mass block angle, angular acceleration, displacement, and linear acceleration information;

[0026] Step 2: The drag-free motion simulation platform measures the angle, angular acceleration, displacement, and linear acceleration information of the satellite platform;

[0027] Step 3: The drag-free payload computer outputs the control force and torque required by the satellite and the electrostatic driving force of the inertial sensor through the designed drag-free controller based on the measurement information of steps 1 and 2;

[0028] Step 4: Based on the calculation result of step 3, the inertial sensor electrostatic drive system controls the movement of the mass block;

[0029] Step 5: Based on the calculation results of step 3, the control force and torque required by the satellite are output by the thruster model and then added with the environmental interference to the satellite, which acts on the satellite dynamics model to cause the satellite to produce corresponding displacement and rotation angle;

[0030] Step 6: The no-drag motion simulation platform control system converts the input quantity into voltage information and outputs it to the no-drag motion simulation platform, thereby controlling the motion of the satellite platform through the no-drag motion simulation platform.

[0031] Step 7: During closed-loop control, the high-precision temperature control system controls the core cabin temperature within the range required by the payload, and the magnetic field measurement system collects magnetic field information from the core cabin.

[0032] Step 8: Use the self-gravity adjustment system to simulate the external self-gravity interference on the inertial sensor and verify the impact of self-gravity changes on the load and drag-free control.

[0033] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0034] The system can achieve high-precision temperature control, magnetic field measurement, self-gravity adjustment and multi-degree-of-freedom drag-free control, simulate the satellite's on-orbit operation state, and complete the coupling experiments between inertial sensors and satellite platforms, and between laser interferometry measurement systems and satellite platforms. It provides an ultra-clean, ultra-precise and ultra-stable satellite experimental platform for detecting gravitational waves in space, greatly reducing the risk and cost of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the satellite platform system structure used for gravitational wave semi-physical experiments.

[0036] Figure 2 This is a schematic diagram of the core module structure, where 1 is the core module body, 2 is the payload shell, 3 is the laser interferometer lens barrel, 4 is the motor cage, and 5 is the optical component.

[0037] Figure 3 This is a flow chart of the satellite platform system control method for gravitational wave semi-physical experiments. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] like Figure 1 As shown in Figure 1, the space gravitational wave semi-physical experimental system consists of a dynamics simulation system, a self-gravitational regulation system, a drag-free motion simulation platform, and a satellite platform. The dynamics simulation system is located outside the vacuum tank, while the remaining components are located inside. The satellite platform includes a magnetic field measurement system, a high-precision temperature control system, a drag-free payload computer, and a core module. The core module consists of inertial sensors and a laser interferometer, and has a torsion balance interface for suspending the inertial sensors.

[0040] The satellite platform is used to integrate a magnetic field measurement system, a high-precision temperature control system, a drag-free payload computer, and a core module, enabling magnetic field measurement and temperature control of the core module, as well as drag-free control of the satellite. The core module is an independently designed structure used to integrate and install the main payload, including high-precision inertial sensors, optical reference plates, primary and secondary mirrors, etc. The main payload is arranged in the center of the core module to avoid thermal interference from other platform structures and individual units. The core module body is made of lightweight materials to form an enclosed temperature-controlled space. The exterior is connected to the main structure of the platform module through multiple points of thermal insulation to minimize heat conduction. A multi-stage thermal control design inside and outside the core module panels ensures high-precision internal temperature control.

[0041] In order to use the torsion balance to conduct high-precision self-gravity measurement tests on the ground, relevant interfaces are reserved for the core module structure and inertial sensors to connect to the torsion balance and build a core module test platform.

[0042] The high-precision temperature control system adopts a combination of active and passive methods. Active temperature control uses a high-precision temperature controller to achieve preliminary suppression of complex external thermal disturbances; passive temperature control will adopt a multi-stage thermal damping method to achieve mK-level control of key components by constructing a low-pass filter for thermal noise.

[0043] The high-precision temperature controller is divided into three modules based on their functions: platinum resistance temperature measurement module 1, platinum resistance temperature measurement module 2, and system management and control module. Platinum resistance temperature measurement module 1 and platinum resistance temperature measurement module 2 are identical modules, differing only in module code. The system management and control module is defined as the internal master node module of the device, while platinum resistance temperature measurement module 1 and platinum resistance temperature measurement module 2 are internal slave nodes. The three modules communicate with each other via an internal CAN bus for data transmission. A PID algorithm is used for precise temperature control, keeping the collected temperature value within ±0.1°C of the set value.

[0044] The core module is simplified into a multi-stage thermal damping system. The two factors that affect the temperature stability of the core temperature control unit are heat capacity C and thermal resistance R. Based on the multi-stage temperature control theory, the thermal resistance between each level is thermally designed on the basis of the existing structural model, mainly including radiation thermal resistance and contact thermal resistance. To enhance the temperature uniformity of each level, the inner surface of each level is coated with a coating with a high emissivity, generally black paint or blackening treatment. Contact thermal resistance mainly refers to the thermal resistance generated when heat is transferred through contact between components at each level. Since the contact heat transfer amount is usually large, the contact thermal resistance is increased as much as possible during the design process, and a thermal insulation installation method is adopted. Fiberglass with low thermal conductivity is used in the scheme.

[0045] The drag-free payload computer is the physical platform for the operation of the drag-free control algorithm. It provides hardware and software support for the implementation of the drag-free control algorithm. It mainly consists of three parts: hardware platform development board, Linux operating system, and payload management software.

[0046] The hardware platform development board is used to verify processor functionality. The Linux operating system is designed to meet complex multi-interface communication requirements. The payload management software utilizes a multi-core design to manage computer peripherals and onboard individual devices, achieving highly flexible timing control.

[0047] A magnetic field measurement system is installed in the satellite core module. Later data processing and analysis can account for magnetic field and fluctuation interference in the model. Each measurement system consists of several magnetometers and supporting brackets. Several ground magnetometers are deployed in each satellite core module. Furthermore, a ground magnetometer A is located outside each satellite module, within the vacuum tank, and a ground magnetometer B is located farther away from the vacuum tank. These magnetometers monitor errors caused by the vacuum tank's magnetic field induction and geomagnetic field fluctuations on the in-module magnetometers.

[0048] A self-gravitation adjustment mechanism is installed within the vacuum tank to provide nanometer-scale adjustable self-gravitation. The self-gravitation adjustment mechanism is a set of wide-guide rail self-gravitation adjustment components that uses a stepper motor to move the mass block to the appropriate position.

[0049] The dynamics simulation system outputs high-precision satellite attitude and orbit information in real time, while also considering the coupling between systems, such as the satellite platform and the proof mass, the satellite platform and the interferometric measurement system, and the coupling between the proof mass and the interferometric measurement system. It includes an attitude and orbit control dynamics simulator and a single-machine interface simulation device for attitude and orbit control.

[0050] The laser interferometer introduces an optical signal delay unit and a wavefront simulation unit to simulate the time and space problems caused by a delay of millions of kilometers in space.

[0051] The inertial sensor includes a suspended test mass block, capacitive sensing, and an electrostatic drive system. It can measure the displacement of the test mass block relative to the satellite body and serve as the input of the displacement drag-free controller. The electrostatic drive system serves as the actuator of the suspension controller, controlling the horizontal displacement (1 degree of freedom) and rotational attitude (3 degrees of freedom) of the test mass block relative to the satellite body.

[0052] The drag-free motion simulation platform is constructed with six-degree-of-freedom piezoelectric ceramics to simulate the five-degree-of-freedom motion of an in-orbit satellite, including frictionless translation in two linear directions in the horizontal plane and three-degree-of-freedom rotation, while also offsetting the impact of gravity on the satellite platform.

[0053] The flow chart of the control method of the satellite platform system for gravitational wave semi-physical experiments is as follows: Figure 3 The specific closed-loop control process is as follows:

[0054] (1) The laser interferometer measures the displacement information between the two satellites, and the inertial sensor measures the angle, angular acceleration, displacement, and linear acceleration information of the mass block;

[0055] (2) The drag-free motion simulation platform measures the angle, angular acceleration, displacement, and linear acceleration information of the satellite platform;

[0056] (3) The drag-free payload computer outputs the control force and torque required by the satellite and the electrostatic driving force of the inertial sensor through the designed drag-free controller based on the measurement information of (1) and (2);

[0057] (4) Based on the calculation results of (3), the inertial sensor electrostatic drive system controls the movement of the mass block;

[0058] (5) According to the calculation results of (3), the control force and torque required by the satellite are output through the thruster model and then added with the environmental interference to the satellite, which acts on the satellite dynamics model to make the satellite produce corresponding displacement and rotation angle;

[0059] (6) The displacement and rotation angle of the satellite are realized by the drag-free motion simulation platform. The simulation platform control system converts the input quantity into voltage information and outputs it to the drag-free motion simulation platform, which controls the movement of the satellite platform through the simulation platform.

[0060] (7) During closed-loop control, the high-precision temperature control system controls the core cabin temperature within the range required by the payload, and the magnetic field measurement system collects magnetic field information of the core cabin;

[0061] (8) The self-gravity adjustment system is used to simulate the external self-gravity interference on the inertial sensor and verify the impact of self-gravity changes on the load and drag-free control.

[0062] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A satellite platform system for semi-physical experiments of gravitational waves, characterized in that: It includes a dynamics simulation system, a self-gravity regulation system, a drag-free motion simulation platform and a satellite platform, wherein the dynamics simulation system is located outside the vacuum tank, and the self-gravity regulation system, the drag-free motion simulation platform and the satellite platform are located inside the vacuum tank; The dynamics simulation system includes an attitude and orbit control dynamics simulator and an attitude and orbit control stand-alone interface simulator. These are used to output high-precision satellite attitude and orbit information in real time, and take into account the coupling between systems, including the coupling between the satellite platform and the proof mass, the coupling between the satellite platform and the interferometric measurement system, and the coupling between the proof mass and the interferometric measurement system. The self-gravitation adjustment system is a set of wide-guide rail self-gravitation adjustment components that uses a stepper motor to move the mass block to the appropriate position, and can provide nanometer-level adjustable self-gravitation. The drag-free motion simulation platform is constructed with six-degree-of-freedom piezoelectric ceramics to simulate the frictionless translation in two linear directions and three-degree-of-freedom rotation in the horizontal plane of the orbiting satellite, a total of five degrees of freedom, and to offset the influence of gravity on the satellite platform. The satellite platform integrates a magnetic field measurement system, a high-precision temperature control system, a drag-free payload computer and a core module to achieve magnetic field measurement and temperature control of the core module and drag-free control of the satellite.

2. The satellite platform system for gravitational wave semi-physical experiments according to claim 1, characterized in that: The satellite platform includes a magnetic field measurement system, a high-precision temperature control system, a drag-free payload computer, and a core module; The magnetic field measurement system is used to collect magnetic field information of the core module and deduct magnetic field and fluctuation interference from the model during subsequent data processing and analysis; The high-precision temperature control system is used to control the core module temperature within the required range for the payload. It adopts a combination of active and passive methods: active temperature control utilizes a high-precision temperature controller to achieve preliminary suppression of complex external thermal disturbances; passive temperature control adopts a multi-stage thermal damping method and achieves mK-level control of key components by constructing a low-pass filter for thermal noise. The drag-free load computer is the physical platform for the operation of the drag-free control algorithm, providing software and hardware support for the implementation of the drag-free control algorithm; The core module is an independently designed structure used for the integrated installation of the main payload, which includes high-precision inertial sensors, optical reference plates, and primary and secondary mirrors.

3. The satellite platform system for gravitational wave semi-physical experiments according to claim 2, characterized in that: The magnetic field measurement system consists of several magnetometers and supporting brackets. Several ground magnetometers are arranged in each satellite core module. A ground magnetometer A is arranged outside each satellite module and inside the vacuum tank. A ground magnetometer B is arranged far away from the vacuum tank to monitor the errors caused by the magnetic induction of the vacuum tank and the fluctuation of the geomagnetic field to the magnetometer in the cabin.

4. The satellite platform system for gravitational wave semi-physical experiments according to claim 2, characterized in that: The high-precision temperature control system consists of a platinum resistance temperature measurement module and a system management and control module. It uses a PID algorithm to achieve precise temperature control, so that the temperature acquisition value is controlled within the range of ±0.1°C of the set value.

5. The satellite platform system for gravitational wave semi-physical experiments according to claim 2, characterized in that: The untowed payload computer includes a hardware platform development board, a Linux operating system, and payload management software. The hardware platform development board is used to verify the processor's functionality; the Linux operating system is used to meet complex multi-interface communication requirements. The payload management software uses a multi-core design to manage computer peripherals and onboard stand-alone devices to achieve high-degree-of-freedom timing control.

6. The satellite platform system for gravitational wave semi-physical experiments according to claim 2, characterized in that: The main load is arranged at the center of the core module. The core module body uses lightweight materials to form a closed temperature-controlled space, and the outside is connected to the main structure of the platform module through multi-point insulation.

7. The satellite platform system for gravitational wave semi-physical experiments according to claim 6, characterized in that: Multi-stage thermal control design is used inside and outside the core module panels to ensure high-precision internal temperature control.

8. The satellite platform system for gravitational wave semi-physical experiments according to claim 6, characterized in that: The core module includes inertial sensors, laser interferometers, and a torsion balance interface for suspending the inertial sensors; The laser interferometer includes an optical signal delay unit and a wavefront simulation unit, which are used to simulate the time and space problems caused by a delay of millions of kilometers in space; The inertial sensor includes a suspended test mass block and a capacitive sensing and electrostatic drive system, which is used to measure the displacement of the test mass block relative to the satellite body as the input of the displacement drag-free controller.

9. The satellite platform system for gravitational wave semi-physical experiments according to claim 8, characterized in that: The electrostatic drive system serves as the actuator of the suspension controller, controlling the relative position of the other degrees of freedom of the test mass with respect to the satellite body.

10. A satellite platform system control method for a semi-physical gravitational wave experiment, characterized in that: The following steps are involved: Step 1: The laser interferometer measures the displacement between the two satellites, and the inertial sensor measures the mass block angle, angular acceleration, displacement, and linear acceleration information; Step 2: The drag-free motion simulation platform measures the angle, angular acceleration, displacement, and linear acceleration information of the satellite platform; Step 3: The drag-free payload computer outputs the control force and torque required by the satellite and the electrostatic driving force of the inertial sensor through the designed drag-free controller based on the measurement information of steps 1 and 2; Step 4: Based on the calculation result of step 3, the inertial sensor electrostatic drive system controls the movement of the mass block; Step 5: Based on the calculation results of step 3, the control force and torque required by the satellite are output by the thruster model and then added with the environmental interference to the satellite, which acts on the satellite dynamics model to cause the satellite to produce corresponding displacement and rotation angle; Step 6: The no-drag motion simulation platform control system converts the input quantity into voltage information and outputs it to the no-drag motion simulation platform, thereby controlling the motion of the satellite platform through the no-drag motion simulation platform. Step 7: During closed-loop control, the high-precision temperature control system controls the core cabin temperature within the range required by the payload, and the magnetic field measurement system collects magnetic field information from the core cabin. Step 8: Use the self-gravity adjustment system to simulate the external self-gravity interference on the inertial sensor and verify the impact of self-gravity changes on the load and drag-free control.

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