Method and system suitable for full-physical simulation of flexible spacecraft attitude dynamics

Abstract

The application provides a method and system suitable for full-physical simulation of attitude dynamics of a flexible spacecraft, and relates to the field of spacecraft dynamics and control technology, and the method comprises the following steps: a static pressure gas lubrication three-axis air bearing table is used to simulate the dynamic environment of the spacecraft in on-orbit flight; the balance of the table body is coarsely adjusted by adding or reducing the weight blocks of the table body, and the slider on the guide rail on the table is finely adjusted to adjust the center of mass of the table body to the origin; inertia identification is performed on the table body to obtain the three-axis rotational inertia of the air bearing table, and a required scale reduction coefficient of the test is determined; a disturbance simulator is used to simulate the flexible disturbance torque generated in the jet process; and the attitude angle of the table body is measured according to different measurement ranges, the influence of the disturbance torque generated by the flexible accessory on the spacecraft is analyzed, and the flexible disturbance torque generator is used to simulate the disturbance torque generated by the vibration of the flexible accessory on the spacecraft, so that the center of mass can be kept unchanged, and the table overturning phenomenon can be avoided; and the application can also provide a reference basis for the design and demonstration of the attitude control scheme of the spacecraft.

Description

Technical Field

[0001] This invention relates to the field of spacecraft dynamics and control technology, specifically to a method and system for full physical simulation of attitude dynamics of flexible spacecraft. Background Technology

[0002] To meet increasingly diverse mission requirements, spacecraft configurations have gradually evolved from rigid to highly flexible. Flexible attachments come in many forms, including antennas, solar panels, and strut mechanisms. For example, high-orbit satellites with large thin-film antennas have been designed, with antenna areas reaching hundreds of square meters. To meet the high-power supply demands of payloads, larger solar arrays are required onboard. To prevent residual magnetism from the satellite platform itself from affecting detectors, lightweight strut mechanisms are used to support various detector payloads. Vibrations of flexible attachments can severely affect the pointing accuracy and attitude stability of the spacecraft platform. Especially during orbit control, when the spacecraft needs to perform orbital maneuvers or maintain its orbital position, the ignition of the orbit control engine with an off-center thrust direction, or the ejection of the attitude control thrusters, can induce flexible vibrations, thus affecting the spacecraft's attitude and, in severe cases, the success or failure of the mission. For instance, in 1990, the Hubble Telescope experienced elastic vibrations due to thermal deformation when entering and exiting shadow areas, resulting in attitude stability failing to meet requirements and thus reducing image quality. In 1982, the US Landsat-4 observation instrument failed to meet expected performance due to interference with its flexible solar panel drive system. Therefore, to meet the requirements for high-precision and high-stability control of spacecraft with flexible components, the control systems of various spacecraft models must undergo full-physical testing on a hydrostatically gas-lubricated triaxial air-bearing platform to verify whether they meet the performance requirements. If the flexible attachments are directly mounted on the air-bearing platform, the change in the center of mass caused by the vibration of the flexible attachments will cause the center of mass of the hydrostatically gas-lubricated triaxial air-bearing platform to deviate from the center of the air-bearing ball bearings, potentially leading to platform collapse.

[0003] Current published literature and patents focus on full-physics simulation methods for flexible spacecraft on single-axis air-bearing platforms, and mature methods have been developed. Li Jisu, Mou Xiaogang, and Wang Chuntao, in their paper "Research on Full-Physical Simulation Technology of Large Flexible Structure Satellites" (Journal of System Simulation, 1995.6), proposed a scheme involving simulation experiments of flexible spacecraft on single-axis air-bearing platforms. They designed a flexible arm mounted on the platform as a simulation device for the flexible structure and presented mathematical simulation results. Zhou Jun and Liu Yingying, in their paper "Research on Full-Physical Simulation Experiment of Active Vibration Feedback for Spacecraft" (Vibration, Testing and Diagnosis, Vol. 28, No. 1, 2008), proposed a scheme to configure a miniature accelerometer at the top of the flexible solar panel of the full-physics simulation system to measure vibration at that location.

[0004] The invention patent with publication number CN104133479A discloses a test method for simulating the three-axis attitude coupling motion of a flexible satellite using a single-axis air-bearing platform. The method includes the following steps: Step 1: Simulate the rigid body motion of the flexible satellite along the X-axis to obtain its X-axis attitude information; Step 2: Construct the flexible satellite, simulate its Y-axis and Z-axis attitude motions, and establish and calculate the vibration dynamics model of the flexible attachments and the space environment disturbance torque model; Step 3: Calculate the Y-axis attitude information and Z-axis attitude information of the flexible satellite, the coupling torque of the flexible attachments, and the space environment disturbance torque; Step 4: Receive signals to control the actuator, torque output device, and single-axis air-bearing platform to simulate the three-axis attitude motion of the flexible satellite; Step 5: Repeat steps 1 to 4 to complete the test of the three-axis attitude coupling motion of the flexible satellite. The above methods are only applicable to single-axis air-bearing platforms and cannot be used for hydrostatically lubricated three-axis air-bearing platforms, as this may result in platform collapse.

[0005] Chinese patent application CN106672272A discloses a ground-based testing system for on-orbit identification of flexible parameters in a spacecraft with a flexible structure. The designed ground testing system includes an air-bearing platform, a rate gyroscope, an attitude control flywheel, an attitude control thruster, a cold jet propulsion system, a flexible spacecraft motion simulator, a vibration measurement system, a ground measurement system, a ground control console, and a motion simulator control computer. This ground simulation verification method, based on a marble air-bearing platform, designs a motion simulator capable of simulating a large flexible spacecraft. The vibration measurement system, rate gyroscope, and ground measurement system obtain the flexible structure vibration information, attitude information, and orbital information of the flexible spacecraft motion simulator, respectively. Combining attitude control and orbital control algorithms, and based on a flexible parameter identification algorithm, the ground simulation testing method verifies the flexible parameter identification scheme.

[0006] The following are some literature and patents regarding the full physical simulation of spacecraft attitude dynamics on a hydrostatically gas-lubricated triaxial air-bearing platform. Chen Huanlong, Zhou Jun, et al., in their paper "Research on Dynamic Simulation Method of Flexible Spacecraft on Hydrostatically Gas-Lubricated Triaxial Air-bearing Platform (English)" (Journal of Astronautics, Vol. 32, No. 4, 2011), proposed an algorithm for simulating flexible disturbance torque using a momentum wheel on a hydrostatically gas-lubricated triaxial air-bearing platform. Their approach involves using a tracking control algorithm to make the air-bearing platform's attitude angular velocity track the reference dynamics of a flexible satellite. This literature focuses on the dynamic simulation algorithm for flexible spacecraft but does not provide specific implementation methods for ground-based experiments.

[0007] The invention patent with publication number CN106020221A discloses an anti-interference attitude control verification platform and method based on output feedback, including a real-time simulation target machine, an attitude determination module, an attitude control module, a reaction flywheel assembly, a test main control module, an interference simulator, and a static pressure gas lubrication triaxial air-bearing platform; the real-time simulation target machine calculates the spacecraft's attitude kinematic model; the attitude determination module filters and solves the attitude information output by the real-time simulation target machine; the attitude control module calculates the attitude control algorithm and provides torque control commands to the reaction flywheel assembly; the reaction flywheel assembly outputs a torque signal to the simulation target machine after receiving the torque control command; the test main control module sends a control method switching signal to the attitude control module, and the anti-interference attitude control unit runs the corresponding control algorithm according to the switching signal; the interference simulator simulates the vibration interference of flexible components; and the static pressure gas lubrication triaxial air-bearing platform simulates the mechanical environment of the spacecraft in outer space. In this patent, the disturbance simulator does not directly generate the actual disturbance torque acting on the air-bearing platform. Instead, it calculates the disturbance torque and inputs it into a real-time simulator. The real-time simulator calculates the dynamic model after incorporating the disturbance torque and then transmits the calculated attitude information to the air-bearing platform control module. The control module obtains the deviation attitude signal from the desired attitude signal to calculate the control torque, which is then transmitted to the flywheel on the platform to act on the platform body. Both of these schemes involve closed-loop control of the disturbance to the air-bearing platform. Furthermore, the disturbance simulator and the actuator on the platform are not two independent modules, and therefore cannot realistically simulate the characteristic of the flexible disturbance torque, which is essentially an external input to the platform body.

[0008] Patent CN108873920A discloses a full-physics simulation test system and method for the attitude dynamics of liquid-filled spacecraft, and introduces the process steps for conducting air-bearing platform experiments on a hydrostatically gas-lubricated triaxial air-bearing platform for liquid-filled spacecraft. Patent CN108803376A discloses a liquid sloshing torque simulation system suitable for full-physics simulation of hydrostatically gas-lubricated triaxial air-bearing platforms, and introduces a liquid sloshing torque simulation device suitable for hydrostatically gas-lubricated triaxial air-bearing platforms. The concept of full-physics simulation for liquid-filled spacecraft can be borrowed from the full-physics simulation of attitude dynamics for flexible spacecraft, but the methods for simulating disturbance torques are completely different. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a method and system for full physical simulation of attitude dynamics of flexible spacecraft.

[0010] According to the present invention, a method and system for full physical simulation of attitude dynamics of flexible spacecraft are provided, the scheme of which is as follows:

[0011] A method and system for full physical simulation of attitude dynamics of flexible spacecraft are provided, the method comprising:

[0012] Step S1: A hydrostatic gas-lubricated three-axis air-bearing platform is used to simulate the dynamic environment of a spacecraft during its on-orbit flight, reflecting the dynamic impact of the disturbance torque generated by the vibration of the flexible attachments on the three-axis attitude of the spacecraft.

[0013] Step S2: Add or remove counterweights to coarsely adjust the balance of the platform, and adjust the sliders on the guide rails of the platform to finely adjust the center of mass of the platform back to the origin.

[0014] Step S3: Use the angular momentum of the flywheel on the platform and the angular velocity information measured by the laser gyroscope to identify the inertia of the platform, obtain the three-axis rotational inertia of the air-bearing platform, and determine the scaling factor required for the test.

[0015] Step S4: Use a staged cold gas thruster to provide control torque for the air-bearing platform, and use a disturbance simulator to simulate the flexible disturbance torque generated during the jet process;

[0016] Step S5: Depending on the measurement range, use an optoelectronic autocollimator, laser tracker, and laser gyroscope integrator to measure the attitude angle of the platform and analyze the influence of the interference torque generated by the flexible attachment on the attitude of the spacecraft.

[0017] Preferably, the center of mass of the platform remains unchanged during the hydrostatic gas lubrication triaxial air-bearing platform test; a flexible torque generation device is used to simulate the vibration frequency of the flexible attachment and the interference torque generated by the vibration of the flexible attachment on the spacecraft.

[0018] The preferred dynamic equations for the flexible spacecraft are as follows:

[0019]

[0020] Among them, I i ω is the satellite's moment of inertia matrix; ω is the spacecraft's attitude angular velocity. H represents the first derivative of the spacecraft's attitude angular velocity ω; H is the angular momentum of the spacecraft's actuators. B represents the first derivative of the angular momentum H of the spacecraft actuator; r η is the rotational coupling coefficient; η is the modal coordinate. T represents the second derivative of the modal coordinate η; s It is the external disturbance torque of the space environment.

[0021] Preferably, for a hydrostatically gas-lubricated triaxial air-bearing platform, its dynamic equation is as follows:

[0022]

[0023] Among them, I p It is the moment of inertia matrix of the air-bearing platform;

[0024] T g =T e+T f It refers to the disturbance torque experienced by the platform, including the flexible disturbance torque. Other disturbance torques T experienced by the platform f ;

[0025] Multiply the above equation by the coefficient k i ,have:

[0026]

[0027] When an appropriate k is chosen i , making k i I p Close to I i If the inertia of the air-bearing platform is considered equivalent to that of a scaled-down spacecraft, then the angular momentum H and torque of the spacecraft's actuators are... Flexible disturbance torque T e Both require equal-amplitude scaling.

[0028] Preferably, the method for simulating the flexible disturbance torque in step S4 specifically includes:

[0029] Step S4.1: The laser gyroscope on the air-bearing platform measures and collects the three-axis angular velocity information of the platform in real time, transmits it to the torque calculation module, and performs differential processing to obtain the angular acceleration, which is used as the input for solving the flexural disturbance torque;

[0030] Step S4.2: Set the model parameters of the flexible attachment and calculate the magnitude of the flexible disturbance torque in real time;

[0031] Step S4.3: Based on the torque distribution algorithm, the speed command is transmitted to each high-torque flywheel.

[0032] Preferably, the model parameters of the flexible attachment in step S4.2 include rotational coupling coefficient, modal frequency, and flexible attachment structural damping. The attitude dynamics equations of the flexible spacecraft are as follows:

[0033]

[0034] Where ω is the spacecraft's attitude angular velocity, ω × Let the cross product matrix be:

[0035]

[0036] Where J is the moment of inertia of the entire star, and H is the angular momentum of the entire star. The torque T represents the disturbance force T generated by the vibration of the flexible attachment on the spacecraft. e , which is the simulated disturbance torque, and T is other external torques.

[0037] Preferably, the calculation formula for distributing the triaxial interference torque, obtained from the flexible attachment, to the inner rotor speed of each high-torque flywheel is as follows:

[0038]

[0039] In the formula, W = [W1 W2 W3 W4] represents the rotational speed of each flywheel, U is the mounting matrix of the flywheels on the platform, and T... e For the flexible disturbance torque, I w This is the moment of inertia of the rotor inside the flywheel about its axis of rotation.

[0040] Preferably, the vibration equation of the flexible attachment is:

[0041]

[0042] Where η represents the modal coordinates, and Let represent the first and second derivatives of η, respectively;

[0043] ξ represents the structural damping of the flexible attachment;

[0044] Ω represents the diagonal matrix of the modal frequencies of the flexible attachment;

[0045] The first derivative of the spacecraft's attitude angular velocity ω;

[0046] B r T Represents the rotational coupling coefficient matrix B r transpose;

[0047] Substituting the vibration equation of the flexible attachment into The formula for calculating the flexible disturbance torque is:

[0048]

[0049] Therefore, the spacecraft attitude dynamics equations are equivalent to the rigid spacecraft attitude dynamics equations, that is...

[0050] A method and system for full physical simulation of attitude dynamics of flexible spacecraft are provided, wherein the disturbance torque simulation device includes:

[0051] Flexible torque generating device: includes multiple high-torque flywheels and cold gas thrusters, used to output flexible torque;

[0052] Laser gyroscope angular velocity measurement module: used to measure the angular velocity of the platform;

[0053] Wireless communication module: used for calculating flexible interference torque and transmitting telemetry data from the platform;

[0054] High-capacity battery: Powers all modules of the flexible disturbance torque simulation system;

[0055] Monitoring module: Composed of an industrial control computer and a monitoring computer, which monitors and displays the magnitude of the flexible disturbance torque.

[0056] Preferably, the flexible torque generating device consists of several high-torque flywheels arranged in a three-orthogonal, three-orthogonal-one-oblique, or multiple-oblique configuration. The flexible torque generating device is fixed on the air-bearing platform by a tooling bracket, so as to realize the exchange of angular momentum between the flywheels and the air-bearing platform, simulating the attitude disturbance torque of a spacecraft with flexible attachments.

[0057] After receiving the gyroscope angular velocity, the wireless communication module calculates the flexural interference torque in real time, generates a flywheel speed command, and sends the flywheel speed remote control command to each high-torque flywheel. At the same time, the wireless communication module transmits telemetry data, including the flywheel speed and interference torque calculation results, to the under-stage monitoring module via wireless communication.

[0058] The flexible torque generating device, the laser gyroscope angular velocity measuring module, the wireless communication module, and the high-capacity battery are all desktop modules. None of the desktop modules contain fans, and the power devices are cooled by heat sinks.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] 1. This invention uses proportional scaling of inertia to meet the needs of full physical simulation experiments for flexible satellites of different sizes;

[0061] 2. By using a flexible disturbance torque generator to simulate the disturbance torque generated by the vibration of flexible attachments on the spacecraft, its center of mass can be kept unchanged, thus avoiding the collapse phenomenon.

[0062] 3. This invention designs an experimental scheme for full physical simulation of the attitude dynamics of spacecraft with flexible attachments, which can provide a reference for the design and demonstration of spacecraft attitude control schemes. Attached Figure Description

[0063] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0064] Figure 1 This is a schematic diagram of the components of a flexible disturbance torque simulation system;

[0065] Figure 2 Here is a flowchart of the flexible disturbance torque simulation system.

[0066] Figure 3 Composition of a full physical simulation system suitable for attitude dynamics of flexible spacecraft;

[0067] Figure 4 A flowchart for full physical simulation of attitude dynamics of flexible spacecraft;

[0068] Figure 5 This is a schematic diagram of a spacecraft model used in a simulation example.

[0069] Figure 6 The simulation example shows the satellite maneuver angle curve;

[0070] Figure 7 The simulation example shows the satellite's maneuver angular velocity curve;

[0071] Figure 8 The simulation example shows the satellite's maneuvering angular acceleration curve;

[0072] Figure 9 The simulation example shows the flexible disturbance torque curve;

[0073] Figure 10 The simulation example shows the high-torque flywheel speed curve;

[0074] Figure 11 To test and measure the three-axis attitude angle data of the air-bearing platform;

[0075] Figure 12 The test measured the three-axis attitude angular velocity data of the air-bearing platform;

[0076] Figure 13 The results of torque calculation for the flexible disturbance simulator on the test platform;

[0077] Figure 14 The purpose is to test and measure the flywheel speed telemetry data of the flexible interference simulator. Detailed Implementation

[0078] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0079] This invention provides a system suitable for full physical simulation of attitude dynamics of flexible spacecraft, referring to... Figure 1 and Figure 2 As shown, it specifically includes:

[0080] Flexible torque generator: Composed of multiple high-torque flywheels, used to output flexible torque. It consists of several high-torque flywheels arranged in a three-orthogonal, three-orthogonal-one-oblique, or multi-oblique configuration. The flexible torque generator is fixed to the air-bearing platform via a fixture bracket, realizing the exchange of angular momentum between the flywheels and the air-bearing platform to simulate the attitude disturbance torque of a spacecraft with flexible attachments. Each high-torque flywheel has both speed and torque modes, with a maximum output torque of not less than 1 Nm, a maximum angular momentum of not less than 20 Nms, a controller bandwidth of not less than 10 Hz, and an external interface using an RS422 serial port. The internal rotor drive motor is a brushless DC torque motor with a rated torque of 1 Nm and a rated speed of 1000 rpm. The angle measuring element uses a circular grating. The internal rotor is made of 45# high-quality carbon steel, and the fixture bracket is made of LY12 hard aluminum.

[0081] Laser gyroscope angular velocity measurement module: used to measure the angular velocity of the platform. The laser gyroscope is used to measure the angular velocity of the platform, and the result is differentiated and used as input for calculating the flexural disturbance torque. Preferably, the external interface uses an RS422 serial port, and the measurement accuracy is higher than 10. -4° / s.

[0082] Wireless communication module: Used for calculating flexural interference torque and transmitting telemetry data from the platform. The flexural interference torque calculation module runs in an xPC industrial computer, communicating with the flywheels and gyroscopes on the platform via two RS422 serial port cards to collect information, calculate the magnitude of the flexural interference torque in real time, generate flywheel speed remote control commands, and send them to each flywheel. By configuring the IP addresses of the wireless communication module and the industrial computer on the platform, a local area network is formed to achieve wireless network communication between the platform and the platform modules, sending telemetry data such as flywheel speed and interference torque calculation results to the platform monitoring module. Preferably, the calculation time for each cycle is 0.2ms, and the minimum interval for command issuance is 0.2ms. The wireless communication distance is greater than 50m, and the transmission rate is better than 600Mbps.

[0083] High-capacity battery: Powers all modules of the flexible disturbance torque simulation system. The high-capacity battery powers all modules of the flexible disturbance torque simulation system, independent of the existing power supply equipment on the air-bearing platform. The power supply has charging and discharging functions; since each module has a different rated operating voltage, the power supply module also has the function of controlling the voltage. Preferably, the power supply module has a capacity of not less than 240Ah, an output voltage of 27-30V, a power of 600W, and a peak-to-peak value of not more than 400mV at full power output. Charging is done via 220V civilian AC power, with a charging time not exceeding 1 hour.

[0084] Monitoring module: Composed of an industrial control computer on the platform and a monitoring computer, it monitors and displays the magnitude of the flexural interference torque. The industrial control computer on the platform receives telemetry data packets sent from the platform, unpacks them according to the communication protocol to obtain the working status of each module in the system, and displays the magnitude of the flexural interference torque in real time.

[0085] Reference Figure 3 and Figure 4 As shown, the method for simulating flexible disturbance torque includes the following steps:

[0086] The laser gyroscope on the air-bearing platform measures and collects the three-axis angular velocity information of the platform in real time, transmits it to the torque calculation module, and performs differential processing to obtain the angular acceleration, which is used as the input for solving the flexural disturbance torque.

[0087] A laser gyroscope is preferred for measuring the angular velocity of the platform. After differential calculation, it serves as the input for calculating the flexural disturbance torque. The sampling frequency is 10Hz, and the measurement accuracy is higher than 10. -4° / s. The formula for difference operation is as follows:

[0088]

[0089] In the formula, ω is the angular acceleration obtained by the difference of the current beat. k+1 ω is the angular velocity measured by the gyroscope at the current beat. k-1 f is the angular velocity measured by the gyroscope in the previous cycle, and f is the gyroscope sampling frequency.

[0090] Set the model parameters of the flexible attachment and calculate the magnitude of the flexible disturbance torque in real time;

[0091] Based on the torque distribution algorithm, the speed command is transmitted to each high-torque flywheel. In this method, the differential angular velocity measured by the gyroscope and the parameters of the flexible attachment model are used as inputs, and the speed of the high-torque flywheel is used as the output.

[0092] The parameters of the flexible attachment model include rotational coupling coefficient, modal frequency, and flexible attachment structural damping, which can be obtained through commercial finite element analysis software.

[0093] The attitude dynamics equations of a flexible spacecraft are as follows:

[0094]

[0095] Where ω is the spacecraft's attitude angular velocity, ω × Let the cross product matrix be:

[0096]

[0097] J is the moment of inertia of the entire star, and H is the angular momentum of the entire star. This can be considered as the disturbance torque T generated by the vibration of the flexible attachment on the spacecraft.e That is, the disturbance torque that this invention aims to simulate, where T represents other external torques.

[0098] The vibration equation for a flexible attachment is as follows:

[0099]

[0100] Substituting the vibration equation of the flexible attachment into have

[0101]

[0102] Therefore, the spacecraft attitude dynamics equations can be equivalent to the rigid spacecraft attitude dynamics equations, that is...

[0103]

[0104] Therefore, on the rigid platform of the air-bearing platform, it is possible to conduct a full physical simulation experiment of the attitude dynamics of flexible spacecraft.

[0105] Based on the torque distribution algorithm, the speed command is transmitted to each high-torque flywheel:

[0106] The high-torque flywheel employs a three-orthogonal-one-oblique mounting configuration to simulate the flexible disturbance torque. The flexible disturbance torque T calculated in the previous step is used... e As input, calculate the rotational speed of each flywheel according to the following control rates.

[0107]

[0108] In the formula, W = [W1 W2 W3 W4] represents the rotational speed of each flywheel, U is the flywheel mounting matrix, and I... w This is the moment of inertia of the flywheel rotor about its axis.

[0109] The mounting matrix U of the flywheel assembly with a three-orthogonal-one-oblique configuration is:

[0110]

[0111] Numerical simulation of the flexible disturbance torque of a flexible spacecraft using Matlab, with the following parameters:

[0112] The satellite is a large satellite with flexible appendages, and its configuration is shown in the attached figure. Figure 5 As shown, the dual-wing solar array is located on the ±Y plane of the satellite, and the satellite is in attitude maneuver mode.

[0113] The satellite's moment of inertia is:

[0114]

[0115] The solar array model was processed using commercial finite element analysis software, and the parameters of the flexible solar array model were obtained as follows:

[0116]

[0117]

[0118] Because the actual inertia adjustment capability of the air flotation platform is between 3500 and 5000 kgm 2 However, the actual satellite inertia is an order of magnitude higher than that of the air-bearing platform, requiring an equivalent scaling down of 25 times.

[0119] The planned maneuver path for the satellite is from [0°, 0°, 0°] to [20°, -30°, -20°], with a maneuver time of 50 seconds. The satellite maneuver angles are shown in the attached diagram. Figure 6 As shown in the attached figure, the satellite's maneuvering angular velocity is... Figure 7 As shown in the attached figure, the satellite's maneuvering angular acceleration is... Figure 8 As shown, angular acceleration is used as the input for the flexible disturbance torque. The calculation of the disturbance torque generated by the vibration of the flexible attachment on the satellite is shown in the attached figure. Figure 9 As shown in the attached diagram. The high-torque flywheels are installed in a three-orthogonal-one-oblique configuration, and the speed distribution of each high-torque flywheel is as follows. Figure 10 As shown.

[0120] A more detailed explanation is provided regarding the full-physics simulation method applicable to the attitude dynamics of flexible spacecraft.

[0121] 1. A hydrostatic gas-lubricated triaxial air-bearing platform is used to simulate the dynamic environment of a spacecraft during its on-orbit flight.

[0122] The hydrostatic gas-lubricated three-axis air-bearing platform enables simulation of free three-axis rotation of a satellite in orbit. The air-bearing ball bearing utilizes compressed air to form an air film between the ball and the bearing housing. This air film counteracts the weight of the air-bearing platform, creating a near-frictionless environment, allowing the platform to rotate freely. The air-bearing platform possesses three-axis inertia adjustment capabilities. It can accurately reflect the dynamic impact of disturbance torques generated by the vibration of flexible attachments on the three-axis attitude of the spacecraft.

[0123] 2. Adjust the platform balance by adding or removing counterweights, and fine-tune the platform's center of gravity to the origin by adjusting the sliders on the platform's guide rails.

[0124] The specific method involves air-bearing the platform and ensuring three-axis stability through a platform-based wheel control system. Telemetry data is then read; if the flywheel speed on a certain axis continuously increases, it indicates the presence of a constant gravitational torque on that axis. The center of gravity of the air-bearing platform is adjusted by changing the counterweight mass or the guide rail slider. Adjusting the platform's center of gravity reduces the static unbalanced torque generated by gravity, thus realistically simulating the microgravity environment of a satellite in orbit on the ground.

[0125] 3. Using the angular momentum of the flywheel on the platform and the angular velocity information measured by the laser gyroscope, the inertia of the platform is identified to obtain the three-axis rotational inertia of the air-bearing platform, and the required scaling factor for the experiment is determined. The principle of scaling is as follows:

[0126] The dynamic equations for a flexible spacecraft are as follows:

[0127]

[0128] Among them, I i ω is the satellite's moment of inertia matrix; ω is the spacecraft's attitude angular velocity. This represents the first derivative with respect to the parameter ω; H is the angular momentum of the spacecraft actuator. This indicates taking the first derivative with respect to parameter H; B r η is the rotational coupling coefficient; η is the modal coordinate. This indicates taking the second derivative with respect to the parameter η; T s It is the external disturbance torque of the space environment.

[0129] For a hydrostatically gas-lubricated triaxial air-bearing platform, its dynamic equations are as follows:

[0130]

[0131] Among them, I p T is the moment of inertia matrix of the air-bearing platform. g =T e +T f It is the disturbance torque (including the flexible disturbance torque) experienced by the platform. Other disturbance torques T experienced by the platform f Multiply the above equation by the coefficient k. i ,have:

[0132]

[0133] When an appropriate k is chosen i , making k i I p Close to I i Then, the inertia of the air-bearing platform can be considered equivalent to that of a scaled-down spacecraft. In this case, the angular momentum H and torque of the spacecraft's actuators are... Flexible disturbance torque T e Both require equal-amplitude scaling.

[0134] 4. A staged cold gas thruster is used to provide control torque for the air-bearing platform, and a disturbance simulator is used to simulate the flexible disturbance torque generated during the jet process.

[0135] The cold gas thruster only provides control torque and does not generate flexible disturbance torque. The cold gas thruster and the disturbance simulator work together to simulate the attitude control conditions of a spacecraft during on-orbit flight. The disturbance simulator is a flexible disturbance torque generation device composed of multiple high-torque flywheels. By measuring the angular velocity input, the module calculates the magnitude of the disturbance torque, generates high-torque flywheel speed commands, and achieves angular momentum exchange with the platform, thereby simulating the effect of flexible attachments on the platform's attitude.

[0136] 5. The attitude angle of the platform is measured by using an opto-collimator, a laser tracker, and a laser gyroscope integrator, and the influence of the disturbance torque generated by the flexible attachment on the attitude of the spacecraft is analyzed.

[0137] When the attitude angle is less than 0.15°, use an electro-optical autocollimator (measurement accuracy 1”); when the attitude angle is less than 30°, use a laser tracker (measurement accuracy 0.002°); when the attitude angle is greater than 30°, use a laser gyroscope integrator when the laser tracker is out of its field of view (integration accuracy 0.005° within half an hour).

[0138] The following is an example of an air-bearing platform test for a certain type of satellite using this invention:

[0139] The simulated satellite operating condition in the experiment was steady-state attitude control during orbital position maintenance. Because the resultant force vector from the orbit control engine could not precisely pass through the center of mass, attitude deflection occurred during orbit control, necessitating the attitude control engine to re-control the attitude. Before the experiment, an attitude deviation of approximately 0.35° along the Z-axis of the test platform was adjusted, and the jet thrusters on the test platform were used to simulate the attitude control engine for attitude correction.

[0140] The flexible disturbance simulator is mounted on the platform in a tri-orthogonal configuration to simulate the impact of flexible attachment vibrations on the satellite platform. The cold gas propulsion system uses jet limit loop control to stabilize the platform's attitude, thereby verifying the satellite's attitude control system.

[0141] Appendix Figure 11 The three-axis attitude angles were measured using a platform-based angle measuring device. Under jet control, the initial Z-axis attitude deviation could be effectively converged within the limiting cycle. (Attached) Figure 12 The three-axis attitude angular velocities were measured by a laser gyroscope on the platform. (Attached) Figure 13 The results of torque calculations for the on-board flexible disturbance simulator are attached. Figure 14 This is the flywheel speed telemetry data from the flexible interference simulator on the platform.

[0142] Initially, the platform exhibits an initial attitude deviation along the Z-axis, triggering the jet thrusters on this axis. Simultaneously, intense flexural vibration occurs along this axis, approximately twice the magnitude of that along the X and Y axes. Furthermore, due to the coupling effect of the flexible components, flexural disturbance torques are also induced along the X and Y axes simultaneously with the Z-axis flexural excitation. Throughout the control process, jet control remains active, and each jet injection induces vibrations in the three-axis flexible attachments. The above experimental results demonstrate the effectiveness and reliability of the experimental method described in this invention, providing a reference for the design of attitude control systems for flexible satellites.

[0143] This invention provides a method and system for full physical simulation of the attitude dynamics of flexible spacecraft, and utilizes proportional scaling of inertia to meet the needs of full physical simulation experiments for flexible satellites of different sizes. During hydrostatic gas-lubricated triaxial air-bearing platform experiments, the center of mass of the platform must remain constant. Therefore, if flexible attachments are directly mounted on the hydrostatic gas-lubricated triaxial air-bearing platform, the vibration of the flexible attachments may cause a change in the center of mass of the platform, leading to platform collapse. By using a flexible disturbance torque generator to simulate the disturbance torque generated by the vibration of the flexible attachments on the spacecraft, the center of mass can be kept constant, avoiding platform collapse. This invention only simulates the influence of spacecraft rotation and the coupled vibration of flexible attachments on attitude, and does not simulate the influence of spacecraft center of mass translation and the coupled vibration of flexible attachments on attitude. The experimental scheme for full physical simulation of the attitude dynamics of spacecraft with flexible attachments designed in this invention can provide a reference for the design and demonstration of spacecraft attitude control schemes.

[0144] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0145] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for full physical simulation of attitude dynamics of flexible spacecraft, characterized in that, include: Step S1: A hydrostatic gas-lubricated three-axis air-bearing platform is used to simulate the dynamic environment of a spacecraft during its on-orbit flight, reflecting the dynamic impact of the disturbance torque generated by the vibration of the flexible attachments on the three-axis attitude of the spacecraft. Step S2: Add or remove counterweights to the platform, coarsely adjust the platform balance, adjust the sliders on the guide rails on the platform, and finely adjust the platform's center of gravity to the origin. Step S3: Use the angular momentum of the flywheel on the platform and the angular velocity information measured by the laser gyroscope to identify the inertia of the platform, obtain the three-axis rotational inertia of the air-bearing platform, and determine the scaling factor required for the test. Step S4: Use a staged cold gas thruster to provide control torque for the air-bearing platform, and use a disturbance simulator to simulate the flexible disturbance torque generated during the jet process; Step S5: Depending on the measurement range, use an optoelectronic autocollimator, laser tracker, and laser gyroscope integrator to measure the attitude angle of the platform and analyze the influence of the interference torque generated by the flexible attachment on the attitude of the spacecraft. The dynamic equations of a flexible spacecraft are as follows: in, It is the satellite's moment of inertia matrix; It is the spacecraft's attitude angular velocity. Represents the angular velocity of the spacecraft's attitude. The first derivative; It is the angular momentum of the spacecraft actuator. Represents the angular momentum of spacecraft actuators The first derivative; It is the rotational coupling coefficient; These are modal coordinates. Represents modal coordinates The second derivative; It is the external disturbance torque of the space environment; For a hydrostatically gas-lubricated triaxial air-bearing platform, its dynamic equations are as follows: in, It is the moment of inertia matrix of the air-bearing platform. It refers to the disturbance torque experienced by the platform, including the flexible disturbance torque. Other disturbance torques on the platform ; Multiply the above equation by the coefficient ,have: When taking appropriate ,make close to If the inertia of the air-bearing platform is considered equivalent to that of a scaled-down spacecraft, then the angular momentum of the spacecraft's actuators will be... and torque Flexible disturbance torque Both require equal-amplitude scaling.

2. The method for full physical simulation of attitude dynamics of flexible spacecraft according to claim 1, characterized in that, During the hydrostatic gas lubrication triaxial air-bearing platform test, the center of mass of the platform remains unchanged; a flexible torque generation device is used to simulate the vibration frequency of the flexible attachment and the interference torque generated by the vibration of the flexible attachment on the spacecraft.

3. The method for full physical simulation of attitude dynamics of flexible spacecraft according to claim 1, characterized in that, The method for simulating the flexible disturbance torque in step S4 specifically includes: Step S4.1: The laser gyroscope on the air-bearing platform measures and collects the three-axis angular velocity information of the platform in real time, transmits it to the torque calculation module, and performs differential processing to obtain the angular acceleration, which is used as the input for solving the flexural disturbance torque; Step S4.2: Set the model parameters of the flexible attachment and calculate the magnitude of the flexible disturbance torque in real time; Step S4.3: Based on the torque distribution algorithm, the speed command is transmitted to each high-torque flywheel.

4. The method for full physical simulation of attitude dynamics of flexible spacecraft according to claim 3, characterized in that, The model parameters for the flexible attachments in step S4.2 include rotational coupling coefficient, modal frequency, and flexible attachment structural damping. The attitude dynamics equations of the flexible spacecraft are as follows: in, For the spacecraft's attitude angular velocity, Let the cross product matrix be: in, For the entire star's rotational inertia, For whole star angular momentum, This represents the disturbance torque generated by the vibration of the flexible attachment on the spacecraft. That is, the simulated disturbance torque. For other external torques.

5. The method for full physical simulation of attitude dynamics of flexible spacecraft according to claim 3, characterized in that, The triaxial disturbance torque is calculated based on the flexible attachment and distributed to the inner rotor speed of each torque flywheel. The calculation formula is as follows: In the formula, For the rotational speed of each flywheel, The mounting matrix of the flywheel on the platform. For flexible disturbance torque, Let t be the moment of inertia of the rotor inside the flywheel about its axis, and t be the integral variable, representing time.

6. The method for full physical simulation of attitude dynamics of flexible spacecraft according to claim 3, characterized in that, The vibration equation of the flexible attachment is: in, Represents modal coordinates, and They represent The first and second derivatives; This indicates the structural damping of the flexible attachment; Represented as a diagonal matrix of modal frequencies of flexible attachments; Represents the angular velocity of the spacecraft's attitude. The first derivative; Represents the rotational coupling coefficient matrix Transpose of; Substituting the vibration equation of the flexible attachment into The formula for calculating the flexible disturbance torque is: Therefore, the spacecraft attitude dynamics equations are equivalent to the rigid spacecraft attitude dynamics equations, that is... .

7. The method for full physical simulation of attitude dynamics of flexible spacecraft according to claim 1, characterized in that, The interference simulator consists of the following components: Flexible torque generating device: includes multiple high-torque flywheels and cold gas thrusters, used to output flexible torque; Laser gyroscope angular velocity measurement module: used to measure the angular velocity of the platform; Wireless communication module: used for calculating flexible interference torque and transmitting telemetry data from the platform; High-capacity battery: Powers all modules of the flexible disturbance torque simulation system; Monitoring module: Composed of an industrial control computer and a monitoring computer, which monitors and displays the magnitude of the flexible disturbance torque.

8. The method for full physical simulation of attitude dynamics of flexible spacecraft according to claim 7, characterized in that, The flexible torque generating device consists of multiple high-torque flywheels arranged in a three-orthogonal, three-orthogonal-one-oblique, or multiple-oblique configuration. The flexible torque generating device is fixed on the air-float platform body by a tooling bracket, so as to realize the exchange of angular momentum between the flywheels and the air-float platform, and simulate the attitude disturbance torque of a spacecraft with flexible attachments. After receiving the gyroscope angular velocity, the wireless communication module calculates the flexural interference torque in real time, generates a flywheel speed command, and sends the flywheel speed remote control command to each high-torque flywheel. At the same time, the wireless communication module transmits telemetry data, including the flywheel speed and interference torque calculation results, to the under-stage monitoring module via wireless communication. The flexible torque generating device, the laser gyroscope angular velocity measuring module, the wireless communication module, and the high-capacity battery are all desktop modules. None of the desktop modules contain fans, and the power devices are cooled by heat sinks.

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