Satellite center of mass change continuous tracking method and system

Abstract

The present invention discloses a method and system for continuously tracking satellite center of mass changes, relating to the field of dynamic tracking of satellite center of mass changes. The method comprises obtaining temperature and pressure data of a cold air cylinder; determining the cylinder's residual mass based on the temperature and pressure data; constructing an observation equation based on the center of mass change of the residual mass and the thruster jet duration; and performing Kalman filtering on the observation equation to obtain a state estimate. The present invention can improve the accuracy of dynamic monitoring of center of mass changes.

Description

Technical Field

[0001] The present invention relates to the field of dynamic tracking of satellite mass center changes, and in particular to a method and system for continuously tracking satellite mass center changes. Background Art

[0002] During in-orbit satellite operations, orbit and attitude adjustments are necessary due to various mission controls or the influence of forces such as solar pressure and atmospheric drag. Currently, the primary method for orbit and attitude maneuvers is high-pressure cold gas propulsion. However, the consumption of cold gas can cause an overall shift in the satellite's center of mass. Large shifts in the satellite's center of mass can also generate significant disturbance torques on the attitude control system, impacting the performance of the high-precision measurement payloads onboard. More seriously, if the disturbance torques exceed the satellite's control capabilities, they can lead to satellite instability or even disintegration. Therefore, for certain satellite missions requiring high-precision (micrometer-level) center of mass changes, high-precision center of mass change tracking and precise center of mass adjustment based on the tracking results are crucial tasks in system operations and control. For example, the Gravitational Earth (GRACE) satellite, a joint US-German mission, requires center of mass changes to be controlled within 100 microns.

[0003] Currently, the main method for calibrating a satellite's center of mass (CM) is to apply a periodic excitation torque significantly greater than the disturbance torque to the satellite using a magnetic torquer or jet propulsion. The satellite's angular acceleration is then measured and detected using a gyroscope or accelerometer, and the satellite's CM is estimated based on the measurement results. The main difficulty in using satellite spin wobble and electrostatic accelerometers for on-orbit CM calibration is the engineering difficulty of spin control. Using the excitation torque of a magnetic torquer combined with a classical Kalman filter for CM calibration is susceptible to colored noise in the observations. While using electrostatically suspended accelerometers and gyroscope data as sensors and a magnetic torquer as an actuator can achieve on-orbit CM calibration, continuous tracking and monitoring are not possible. Given that CM variations are primarily caused by mass changes in the gas cylinder, monitoring the remaining mass of the gas cylinder can enable dynamic monitoring of CM variations.

[0004] Using the satellite's gas cylinder temperature and pressure sensors, combined with the gas's equation of state, it's possible to estimate the remaining mass of the gas in real time. Because the onboard computer can record the operating duration of each thruster with millisecond accuracy, filtering the remaining mass of the gas cylinder based on the thruster's jet duration can further improve the accuracy of the remaining mass, thereby increasing the accuracy of the center of mass change estimate. However, a mature implementation method is currently lacking. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for continuously tracking satellite mass center changes, which can improve the accuracy of dynamic monitoring of mass center changes.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A method for continuously tracking changes in satellite mass center, comprising:

[0008] Get the air temperature and pressure data of the cold air cylinder;

[0009] determining the remaining mass of the gas cylinder according to the air temperature and the air pressure data;

[0010] constructing an observation equation based on the center of mass change of the residual mass and the thruster jet duration;

[0011] Kalman filtering is performed according to the observation equation to obtain a state estimation value.

[0012] Optionally, determining the remaining mass of the gas cylinder according to the air temperature and the air pressure data specifically includes:

[0013] Determine the gas volume and gas density using the state equation of the gas according to the air temperature and the air pressure data;

[0014] The remaining mass of the gas cylinder is determined according to the gas volume, the gas density, the jetting time of the thruster and the jetting mass rate.

[0015] Optionally, constructing an observation equation based on the change in the center of mass of the residual mass and the thruster jet duration specifically includes:

[0016] The residual mass of each gas cylinder and the changing torque of the gas cylinder mass are taken as observation values, and the jet mass rate of each thruster is taken as a parameter to be estimated, and an observation equation is constructed.

[0017] The present invention also provides a satellite mass center change continuous tracking system, comprising:

[0018] The acquisition module is used to obtain the air temperature and pressure data of the cold air cylinder;

[0019] a remaining mass determination module, configured to determine the remaining mass of the gas cylinder according to the air temperature and the air pressure data;

[0020] A construction module, configured to construct an observation equation based on the center of mass change of the residual mass and the thruster jet duration;

[0021] The state estimation value determination module is used to perform Kalman filtering according to the observation equation to obtain the state estimation value.

[0022] Optionally, the remaining mass determination module specifically includes:

[0023] a gas volume and gas density determining unit, configured to determine the gas volume and gas density using a gas state equation according to the temperature and the air pressure data;

[0024] The remaining mass determination unit is used to determine the remaining mass of the gas cylinder according to the gas volume, the gas density, the jetting time of the thruster and the jetting mass rate.

[0025] Optionally, the building blocks specifically include:

[0026] A construction unit is used to take the residual mass of each gas cylinder and the changing torque of the gas cylinder mass as observation values, and the jet mass rate of each thruster as a parameter to be estimated, to construct an observation equation.

[0027] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0028] The present invention obtains air temperature and pressure data from a cold air cylinder; determines the cylinder's residual mass based on the air temperature and pressure data; constructs an observation equation based on the residual mass and the center of mass change of the thruster jet duration; and performs Kalman filtering based on the observation equation to obtain a state estimate. This invention can improve the accuracy of dynamic monitoring of center of mass changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 This is a schematic diagram of the method for continuously tracking the satellite's center of mass change;

[0031] Figure 2 This is an overall schematic diagram of the method for continuously tracking satellite center of mass changes;

[0032] Figure 3 This is a flow chart of the method for continuously tracking satellite center of mass changes provided by the present invention. DETAILED DESCRIPTION

[0033] 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.

[0034] The purpose of the present invention is to provide a method and system for continuously tracking satellite mass center changes, which can improve the accuracy of dynamic monitoring of mass center changes.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 3 As shown, the present invention provides a method for continuously tracking changes in satellite center of mass, comprising:

[0037] Step 001: Obtain the air temperature and pressure data of the air conditioning cylinder.

[0038] Step 002: Determine the remaining mass of the gas cylinder according to the air temperature and the air pressure data.

[0039] Step 002 specifically includes: determining the gas volume and gas density using the gas state equation according to the air temperature and the air pressure data; and determining the remaining mass of the gas cylinder according to the gas volume, the gas density, the thruster injection time and the injection mass rate.

[0040] Calculating the remaining mass of the cold air cylinder based on its air temperature and pressure data involves using the cylinder's telemetered air temperature and pressure data, combined with the gas equation of state, to calculate the volume and density of the gas, thereby calculating the remaining mass of the gas in the cylinder. The remaining mass of the gas in the cylinder is estimated using the cylinder's air temperature and pressure telemetry data and the gas equation of state. The gas consumption mass is filtered using the jet duration of all thrusters, resulting in a more accurate estimate of the remaining mass of the gas in the cylinder.

[0041] Step 003: Construct an observation equation based on the center of mass change of the residual mass and the thruster jet duration.

[0042] Step 003 specifically includes:

[0043] The residual mass of each gas cylinder and the changing torque of the gas cylinder mass are taken as observation values, and the jet mass rate of each thruster is taken as a parameter to be estimated, and an observation equation is constructed.

[0044] Step 004: Perform Kalman filtering according to the observation equation to obtain a state estimate.

[0045] The gas mass change is filtered based on the cumulative jet time of each satellite thruster, including:

[0046] The jet duration of each thruster is generally timed in milliseconds by the onboard computer. Combining the jet duration of each thruster and the jet mass rate, the mass consumption of the cylinder gas can be accurately calculated, thereby accurately determining the change in the cylinder mass.

[0047] A center of mass change filter that combines the remaining mass of the tank and the duration of the thruster jet, including:

[0048] The remaining mass of each cylinder and the torque caused by the cylinder mass change are used as observations. The three components of the center of mass change (x, y, and z) and the jet mass rate of each thruster are used as estimated parameters to construct the corresponding observation equations. The system's state equations are constructed under the assumption that the jet mass rate of each thruster is constant and that the center of mass change is entirely caused by the cylinder mass change. For each thruster event, the above measurement equations and state equations are constructed and solved using an extended Kalman filter to obtain the center of mass change at the current moment. This is done until all thruster events are processed.

[0049] The mass of gas consumed in the cylinder and the torque change caused by the mass change are used as observation vectors, and the variance and covariance matrix of the observation vector are set based on experience. This constructs the observation equation of the Kalman filter. In the Kalman filter of the state vector, the state vector is set to the three components of the center of mass change and the mass rate of all thruster jets. In the state transition equation, it is assumed that the center of mass remains unchanged between two consecutive thruster events, and the thruster jet mass rate is a constant value. Based on the above assumptions, the state transition equation is constructed. The center of mass change is estimated using the Kalman filter, and a real-time filtered estimation is performed when each thruster event occurs, thereby tracking the satellite center of mass change in real time.

[0050] The process of constructing the state equation is:

[0051] For example, consider a satellite with two gas cylinders, each connected to seven thrusters. The constructed state vector includes three center-of-mass change components and the jet mass rates of the 14 thrusters. Because the primary component of the satellite's center-of-mass change comes from the thrusters consuming the gas from the cylinders, it is assumed to remain unchanged when no thruster events occur. Furthermore, the jet mass rate of each thruster remains constant during operation. Based on this analysis, the state transition matrix can be considered the identity matrix. The state equation from time k to time k+1 is then constructed, and state transitions are implemented based on this equation.

[0052] The construction process of the observation equation is:

[0053] First, the remaining gas mass in the cylinder is calculated based on the gas state equation, combined with the telemetered cylinder air temperature and pressure data. This is then compared with the initial time, yielding the gas mass consumed from the initial time to the current time. The gas mass consumed is then derived from the total operating time of each thruster stored in the onboard computer and the a priori thruster jet mass rate. Combining these two physical quantities constructs the first two equations in the observation system. Simultaneously, changes in gas mass lead to changes in torque, and the torque balance equation links changes in the center of mass to changes in torque. This allows the construction of the remaining three observation equations. Once the observation equations are constructed, the variance and covariance of each observation value are empirically set.

[0054] 1. The present invention realizes automatic monitoring of satellite center of mass changes through the temperature and pressure data of the gas cylinder, thereby improving the timeliness of continuous monitoring and regulation of satellite center of mass changes.

[0055] 2. The present invention utilizes the state equation of the cold gas cylinder and the jetting duration of each thruster to achieve accurate estimation of the remaining mass of the cylinder.

[0056] 3. The present invention uses the jet duration of the thruster to filter the remaining mass of the gas cylinder to estimate the center of mass change. Compared with other methods, it does not require additional maneuvers to be imposed on the satellite and has no impact on other subsystems of the satellite.

[0057] 4. The center of mass change estimation accuracy of the present invention can reach 50 microns, which can provide continuous, stable and reliable center of mass changes for high-precision satellite missions.

[0058] The present invention also provides a method for tracking satellite center of mass changes based on the air temperature and pressure of the gas cylinder.

[0059] like Figure 1 As shown, the present invention provides a satellite center of mass change tracking method based on the cylinder temperature and pressure, which can continuously monitor the satellite center of mass change with an accuracy of 50 microns, including:

[0060] Step 100: Select the initial filtering time and input the three components of the satellite's center of mass (x, y, and z) at the initial time, as well as the initial mass of the gas in the cylinder. At the same time, obtain the installation location of the cylinder and the position of the cylinder's own center of mass in the satellite's coordinate system, the physical properties of the gas in the cylinder, and the nominal volume of the cylinder from the satellite manufacturer.

[0061] Step 101: Obtain the temperature and pressure data of the gas in all gas cylinders and the jet duration data of each thruster; and calculate the remaining mass of the gas in the gas cylinders based on the physical property parameters of the gas.

[0062] Step 102: Set the initial state of the Kalman filter based on the initial center of mass, construct the state equation, and set the state transition noise.

[0063] Step 103: construct an observation value matrix based on the remaining mass of each gas cylinder and the center of mass position of each gas cylinder, and set the variance-covariance matrix of the observation values.

[0064] Step 104: According to the system state equation, the system state vector at the initial moment is used to perform a one-step prediction to obtain the system state vector at the current moment and its variance-covariance matrix.

[0065] Step 105: Perform measurement update based on the observation equation at the current moment.

[0066] Step 106: Determine the state estimation vector at the next moment and the variance-covariance matrix of the state estimation vector at the next moment according to the state vector at the current moment, the filter gain, and the measurement noise.

[0067] Step 107: Use the current state estimation vector as the new initial value and return to step 100 until all thruster data at all times are processed, and then output the best estimate of the state vector at all times and its variance and covariance.

[0068] The process of constructing the state equation used in the present invention is as follows:

[0069] Step 1. Set the system state vector to the x, y, and z components of the center of mass change, as well as the jet mass rate of each thruster. For example, consider a satellite with two gas cylinders, each connected to six attitude control thrusters and one orbit control thruster. The system state vector is a column vector with 17 rows and 1 column. The system state vector matrix is ​​a symmetric matrix with 17 rows and 17 columns.

[0070] Step 2: Based on the cylinder's residual mass calculated from the cylinder's temperature and pressure data, combined with the cylinder's initial gas mass, the cylinder's mass change at the current moment can be calculated, thereby calculating the x, y, and z components of the center of mass change in the system state vector. The jet mass rate of each thruster is assumed to be constant, with its state unchanged between two consecutive moments. Based on these assumptions, the system transfer matrix is ​​set, which is a 17-row, 17-column matrix.

[0071] Step 3: Set the system transfer noise matrix based on experience. The system transfer noise matrix is ​​a diagonal matrix with 17 rows and 17 columns.

[0072] The construction process of the observation equation used in the present invention is as follows:

[0073] Step 1: Utilize the temperature and pressure telemetry data from all cylinders, combined with the actual gas state equation, to calculate the actual gas volume and density, thereby obtaining the gas mass. The gas mass change for each cylinder is then calculated based on the initial gas mass.

[0074] Step 2: The change in gas mass in the cylinder is primarily due to the consumption of the jets from each thruster. Therefore, the change in gas mass can be expressed as the product of the jet mass rate of each thruster and the total jet duration. Based on this principle, an observation equation can be formulated that relates the thruster jet mass rate and the change in gas mass in the system state vector.

[0075] Step 3: Under the premise that the center of mass of the gas cylinder itself does not change, changes in the gas mass in the gas cylinder will cause the center of mass of the satellite to change. The relationship between the center of mass change and the torque in the system state vector can be obtained based on the torque balance equation; based on this, the observation equation between the center of mass change and the torque is constructed.

[0076] The following is Figure 2 Taking the implementation architecture as an example, the specific implementation process of the satellite center of mass change tracking method based on the cylinder temperature and pressure provided by the present invention is illustrated, but it is not limited to this in actual application.

[0077] Based on the above description, the technical concept adopted by this invention is to calculate the mass change of the gas cylinder relative to the initial moment based on the gas cylinder temperature and pressure data and the thruster jet duration. The extended Kalman filter method is used to process the thruster jet events to solve the satellite's center of mass change and the jet mass rate of each thruster. The specific method is as follows:

[0078] The first step is to construct the state equation: set the system's state vector, and set the system's state transfer matrix and the process noise of the state transfer equation based on experience. The state equation can be used to predict the state at the next moment from the current state. The specific steps for establishing the state equation are:

[0079] Assume that a certain model of satellite has two gas cylinders, and each gas cylinder is connected to six attitude control thrusters and one orbit control thruster. Set the system state vector to:

[0080]

[0081] Where Δx, Δy, and Δz are the changes in the satellite center of mass in three directions respectively; are the jet mass rates of the seven thrusters connected to cylinder No. 1; are the jet mass rates of the 7 thrusters connected to the No. 2 gas cylinder; the satellite center of mass change at the initial moment can be set to 0, and the thruster mass rate is set according to the nominal value given by the satellite manufacturer. The variance covariance matrix of the initial state , where D Δx ,D Δy ,D Δz are the variances of the initial centroid changes in the three directions; are the variances of the mass rates of the seven thrusters of cylinder 1; are the variances of the mass rates of the seven thrusters of gas cylinder No. 2; in actual data processing, the values ​​of these prior variances should be set according to the actual conditions of the satellite platform and thrusters.

[0082] Since the satellite mass center does not change between two thruster jet events, and the jet mass rate of each thruster remains constant, the state transfer matrix Φ in the system state transfer equation is k,k-1 Can be set to the identity matrix I 17×17 , both Φ k,k-1 =I 17×17 ; The state transition equation from time k-1 to time k is: The transfer equation of the variance-covariance matrix is: in is the one-step predicted state vector at time k; is the variance covariance matrix of the one-step predicted state vector. k is the system state prediction noise, which can be set based on experience. k-1 is the system state variance-covariance matrix at time k-1; is the transpose of the system state transfer matrix.

[0083] The second step is to establish the observation equation: the change in gas mass in the two cylinders and the change in torque caused by the mass change are used as observation vectors, and the variance matrix of the observation value is set based on experience. The specific details of the observation equation are as follows:

[0084] First, calculate the remaining gas mass in the gas cylinder. The process of calculating the gas mass in the gas cylinder based on the Peng-Robinson gas state equation is as follows:

[0085]

[0086]

[0087]

[0088]

[0089] β=0.37464+1.54226ω-0.26992ω 2

[0090] Where P and T are the gas pressure and temperature respectively, Vm is the molar volume, T c is the critical temperature of the gas, P c is the critical pressure of gas, R=8.314 is the ideal gas constant; ω is the eccentricity coefficient; a is a temporary variable, b is a temporary variable, α(T) is a temporary variable, and β is a temporary variable.

[0091] Using the above real gas equation, the molar volume V can be calculated using the air temperature and pressure telemetry data. m ; then the gas density is:

[0092]

[0093] Where M is the molecular mass of a gas, in kg / mol.

[0094] After solving for the gas density ρ(P,T), the residual mass of the gas can be calculated by accurately solving for the true volume of the gas. Generally speaking, when a gas cylinder is filled with high-pressure gas, the cylinder volume will expand and deform. The volume of the cylinder at the maximum working pressure is usually measured. Assuming that the volume deformation maintains a linear relationship with the gas pressure, the volume of the cylinder when the cylinder pressure is P is:

[0095]

[0096] Among them, P max and V max are the maximum working pressure and the volume of the gas cylinder at the maximum working pressure; P0 and V0 are the standard atmospheric pressure and the volume of the gas cylinder under standard atmospheric pressure. The remaining gas mass of the gas cylinder is:

[0097] m=ρ(P,T)·V

[0098] The mass changes of all gas cylinders relative to the initial moment are then calculated as observation values. For a certain model of satellite with two gas cylinders, the values ​​are Δm1 = m1(t0) - m1(t); and Δm2 = m2(t0) - m2(t). The following relationship is then obtained based on the moment balance equation:

[0099] (m1(t)+m2(t)+m dry )Δx=Δm1x1+Δm2x2-(Δm1+Δm2)x0

[0100] Where m1(t0) and m2(t0) are the remaining masses of the gas cylinder at the initial moment; m1(t) and m2(t) are the remaining masses of the gas cylinder at time t, respectively. dry is the satellite's dry weight. x0 is the satellite's center of mass at the initial moment; x1 and x2 are the centers of mass of the two gas cylinders, respectively. Δx=(Δx Δy Δz) Tis the change in satellite center of mass due to the change in gas cylinder mass. Δm1 is the change in mass of gas cylinder 1, and Δm2 is the change in mass of gas cylinder 2.

[0101] According to the above analysis, the observation vector can be constructed as:

[0102]

[0103] Corresponding to the observation vector, the design matrix can be constructed as:

[0104]

[0105] in are the total jet durations of the 7 thrusters connected to cylinder 1, are the jet durations of the seven thrusters connected to cylinder 2; the matrix form of the observation equation is: L = B·X; the variance-covariance matrix of the observation value is set according to experience: R_obs = diag(10 -8 10 -8 10 -12 10 -12 10 -12 ); L is the observation vector.

[0106] The third step is to calculate the filter parameters: The initial state and observation data are input into the extended Kalman filter. The state equation is used to predict the next-step state estimate. The next-step state estimate is then solved based on the observation equation and the next-step observation. Repeating these steps (including time updates and measurement updates) through multiple iterative updates yields the optimal estimate of the state parameters, thereby enabling dynamic monitoring and tracking of center of mass changes.

[0107] The specific details of parameter estimation using Kalman filtering are as follows:

[0108] Input t k-1 The estimated state vector at time As the initial value, and calculate its variance covariance matrix

[0109] According to the set transfer matrix And by the state one-step prediction equation Get t k One-step state estimate at time

[0110] Calculate one-step state estimate The variance-covariance matrix of in is the variance matrix of the system process noise, is the noise distribution matrix. From the observation equation we get is the residual, To design the matrix, calculate the filter gain in is the covariance matrix of the measurement noise.

[0111] Using the filter gain and real observation data, we can get t according to the state estimation equation. k State estimation at the moment And the variance-covariance matrix of the state variables at this moment is the gain matrix.

[0112] Repeat the above steps and iterate and update continuously until the states at all moments are processed and the best estimate of the state vector is obtained.

[0113] In summary, the present invention addresses the problems of previous satellite center of mass methods, such as the inability to continuously track and monitor the center of mass and the need for additional maneuvers to calibrate the center of mass. By doing so, it proposes a method for continuously monitoring center of mass changes using data on gas cylinder mass changes and thruster operating hours. This method calculates the mass of the gas cylinder using the gas state equation and filters the changes in the gas cylinder mass in combination with the thruster operating hours, improving the accuracy of the calculation of the gas cylinder mass changes and, consequently, the accuracy of dynamic monitoring of center of mass changes. This method can also be applied to monitoring center of mass changes on all spacecraft that utilize gas cylinders for maneuvers, demonstrating its universal applicability and broad application prospects.

[0114] The present invention also provides a satellite mass center change continuous tracking system, comprising:

[0115] The acquisition module is used to obtain the air temperature and pressure data of the cold air cylinder.

[0116] The remaining mass determination module is used to determine the remaining mass of the gas cylinder according to the air temperature and the air pressure data.

[0117] A construction module is used to construct an observation equation based on the center of mass change of the residual mass and the thruster jet duration.

[0118] The state estimation value determination module is used to perform Kalman filtering according to the observation equation to obtain the state estimation value.

[0119] As an optional implementation manner, the remaining mass determination module specifically includes:

[0120] The gas volume and gas density determination unit is used to determine the gas volume and gas density using the state equation of the gas according to the air temperature and the air pressure data.

[0121] The remaining mass determination unit is used to determine the remaining mass of the gas cylinder according to the gas volume, the gas density, the jetting time of the thruster and the jetting mass rate.

[0122] As an optional implementation, the building block specifically includes:

[0123] A construction unit is used to take the residual mass of each gas cylinder and the changing torque of the gas cylinder mass as observation values, and the jet mass rate of each thruster as a parameter to be estimated, to construct an observation equation.

[0124] The present invention calculates the gas density and mass in the cylinders using the gas state equation based on satellite telemetry of the cylinder's air temperature and pressure. The mass of the remaining gas in the cylinders is filtered using the jet duration of each thruster. Because the thruster jet duration has good measurement accuracy, the accuracy of the remaining gas mass after filtering is better than that calculated directly using the cylinder air temperature and pressure data. Based on this, the Kalman filter estimates the satellite's center of mass change and the jet mass rate of each thruster using the moment balance equation.

[0125] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0126] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for continuously tracking changes in satellite mass center, characterized in that: include: Get the air temperature and pressure data of the cold air cylinder; determining the remaining mass of the gas cylinder according to the air temperature and the air pressure data; constructing an observation equation based on the center of mass change of the residual mass and the thruster jet duration; Performing Kalman filtering according to the observation equation to obtain a state estimate; The satellite consists of multiple gas cylinders, each of which is connected to multiple thrusters. The change in the satellite's center of mass mainly comes from the thrusters consuming the gas in the cylinders. The process of constructing the observation equation includes: constructing the observation equation between the thruster jet mass rate and the change in gas mass in the system state vector based on the residual mass; the change in gas mass leads to a change in torque, and the observation equation between the center of mass change and torque is constructed using the torque balance equation based on the center of mass change and torque transformation; The construction process of the state equation in the Kalman filter process includes determining the variance covariance matrix and the system state vector according to the thruster mass rate and center of mass change; determining the state equation according to the state transfer matrix, the variance covariance matrix and the system state vector; The extended Kalman filter is used to predict the one-step state estimate at the next moment based on the state equation. The state estimate at the next moment is solved based on the observation equation and the observation value at the next moment. The above steps are repeated and the optimal state estimate is obtained through multiple iterative updates.

2. The method for continuously tracking satellite center of mass changes according to claim 1, characterized in that: The determining the remaining mass of the gas cylinder according to the air temperature and the air pressure data specifically includes: Determine the gas volume and gas density using the state equation of the gas according to the air temperature and the air pressure data; The remaining mass of the gas cylinder is determined according to the gas volume, the gas density, the jetting time of the thruster and the jetting mass rate.

3. The method for continuously tracking satellite center of mass changes according to claim 1, wherein: The observation equation is constructed based on the change in the center of mass of the residual mass and the thruster jet duration, specifically including: The residual mass of each gas cylinder and the changing torque of the gas cylinder mass are taken as observation values, and the jet mass rate of each thruster is taken as a parameter to be estimated, and an observation equation is constructed.

4. A satellite mass center change continuous tracking system, characterized in that: include: The acquisition module is used to obtain the air temperature and pressure data of the cold air cylinder; a remaining mass determination module, configured to determine the remaining mass of the gas cylinder according to the air temperature and the air pressure data; A construction module, configured to construct an observation equation based on the center of mass change of the residual mass and the thruster jet duration; A state estimation value determination module is used to perform Kalman filtering according to the observation equation to obtain a state estimation value; The satellite consists of multiple gas cylinders, each of which is connected to multiple thrusters. The change in the satellite's center of mass mainly comes from the thrusters consuming the gas in the cylinders. The process of constructing the observation equation includes: constructing the observation equation between the thruster jet mass rate and the change in gas mass in the system state vector based on the residual mass; the change in gas mass leads to a change in torque, and the observation equation between the center of mass change and torque is constructed using the torque balance equation based on the center of mass change and torque transformation; The construction process of the state equation in the Kalman filter process includes determining the variance covariance matrix and the system state vector according to the thruster mass rate and center of mass change; determining the state equation according to the state transfer matrix, the variance covariance matrix and the system state vector; The extended Kalman filter is used to predict the one-step state estimate at the next moment based on the state equation. The state estimate at the next moment is solved based on the observation equation and the observation value at the next moment. The above steps are repeated and the optimal state estimate is obtained through multiple iterative updates.

5. The satellite mass center change continuous tracking system according to claim 4, characterized in that: The remaining mass determination module specifically includes: a gas volume and gas density determining unit, configured to determine the gas volume and gas density using a gas state equation according to the temperature and the air pressure data; The remaining mass determination unit is used to determine the remaining mass of the gas cylinder according to the gas volume, the gas density, the jetting time of the thruster and the jetting mass rate.

6. The satellite mass center change continuous tracking system according to claim 4, characterized in that: The building blocks specifically include: A construction unit is used to take the residual mass of each gas cylinder and the changing torque of the gas cylinder mass as observation values, and the jet mass rate of each thruster as a parameter to be estimated, to construct an observation equation.

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