Satellite instantaneous force anomaly analysis method based on angular momentum conservation

Abstract

The present invention provides a satellite instantaneous force anomaly analysis method based on angular momentum conservation, and calculates the angular momentum change through relative angular momentum difference analysis or whole satellite angular momentum change analysis. If the satellite angular momentum changes instantaneously, it is judged that the satellite is subjected to an instantaneous external force in space; the relative angular momentum difference analysis is to calculate and analyze the difference between the instantaneous satellite rotating component angular momentum change and the satellite rotation angular momentum change. If the difference is not 0, it is judged that the satellite is subjected to an external force; the whole satellite angular momentum change analysis is to combine the angular momentum of the star body, the angular momentum of the flywheel and the angular momentum of other rotating components into the whole satellite angular momentum, and calculate the satellite angular momentum change according to the calculation results of the three-axis composite angular momentum before and after the anomaly. The present invention can provide direct data support for satellite attitude anomaly positioning, source tracing analysis and collision direction speculation.

Description

Technical Field

[0001] The invention belongs to the field of aerospace measurement and control, and relates to a satellite force anomaly analysis method. Background Art

[0002] During their operation, satellites in orbit face threats from a complex space environment. Space debris and micrometeoroids travel at high speeds in space and have extremely high kinetic energy. If they collide with spacecraft, they will cause serious harm to the latter. my country has the ability to monitor larger space targets and avoid and control satellites, but due to technical limitations, tiny space debris and micrometeoroids still pose a great threat to my country's spacecraft in orbit. In the event of a collision with tiny debris, satellites may experience major anomalies such as damage to components, instability in attitude, or even disintegration. How to separate whether satellite anomalies are caused by internal factors or external impacts is very important for the positioning and disposal of satellite anomalies, as well as the country's research and judgment on space events and external voice.

[0003] There is no public research method in this field for satellite anomalies that may be caused by external impact. At present, the main methods used in China are telemetry data phenomenon analysis, ground tests and simulations, but such methods can generally only speculate on the cause of the anomaly, and cannot directly prove that the satellite anomaly is caused by external impact. At the same time, it is difficult to judge the direction and route of the external impact. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a method for analyzing satellite instantaneous force anomalies based on the conservation of angular momentum. By analyzing and determining the satellite gyroscope measurement output, the rotation speed of rotating parts, and the rotational inertia characteristics of the entire satellite and rotating parts, the instantaneous change of angular momentum before and after the satellite anomaly is calculated, and it is determined whether the satellite anomaly is caused by instantaneous external force in space, which provides direct data support for satellite attitude anomaly positioning, source tracing analysis and collision direction speculation.

[0005] The technical solution adopted by the present invention to solve the technical problem includes the following steps: calculating the angular momentum change by relative angular momentum difference analysis or whole satellite angular momentum change analysis, and if the satellite angular momentum changes instantaneously, it is judged that the satellite is subjected to an instantaneous external force in space;

[0006] The relative angular momentum difference analysis is to calculate and analyze the difference between the instantaneous change in the angular momentum of the satellite's rotating parts and the change in the angular momentum caused by the satellite's rotation. If the difference is not 0, it is determined that the satellite is subject to external forces.

[0007] The whole-satellite angular momentum change analysis is to combine the star body angular momentum, flywheel angular momentum and other rotating parts angular momentum into the whole-satellite angular momentum, and calculate the satellite angular momentum change according to the calculation results of the three-axis composite angular momentum before and after the anomaly.

[0008] The relative angular momentum difference comprises the following steps:

[0009] The satellite body angular momentum calculation model is established as In the formula, H sat_x , H sat_y , H sat_z They represent the components of the satellite's angular momentum in each direction; I is the satellite's moment of inertia matrix in each direction, is the ground measurement value, and the subscripts represent the matrix elements; ω x ,ω y ,ω z is the component of the satellite's inertial angular velocity in each direction of the system, obtained through gyro combined telemetry;

[0010] The satellite body's synthetic angular momentum is

[0011] The change in the rotation speed of the satellite's rotating parts causes the transformation of the satellite's angular momentum, and a calculation model for the three-axis angular momentum of the rotating parts is established. In the formula, H ZD is the angular momentum of the rotating part, I ZD is the moment of inertia of the rotating part, ω ZD is the rotating parts speed;

[0012] Composite angular momentum of satellite's rotating parts

[0013] Calculate the change in angular momentum H 差 =H sat_合 -H ZD_合 .

[0014] The whole-star angular momentum change analysis comprises the following steps:

[0015] Calculate the angular momentum H of the star sat Decompose into components in each direction Where I is the satellite's moment of inertia in all directions, and ω is the ground measurement value; x ,ω y ,ω z is the component of the satellite inertial angular velocity in this system, obtained through gyro combined telemetry;

[0016] Calculate the total angular momentum of the flywheel In the formula, I n is the moment of inertia of a certain flywheel, ω n_x ,ω n_y ,ω n_z are the speed components of the nth flywheel in the three axes of X, Y and Z respectively;

[0017] Calculating the angular momentum of a rotating part In the formula, I ZD is the moment of inertia of the rotating part, ω ZD is the rotating parts speed;

[0018] The above angular momentum is combined to get the angular momentum of the whole star. In this system, each component is

[0019]

[0020] Then we can get the three-axis composite angular momentum The change of satellite angular momentum is calculated based on the calculation results of the three-axis composite angular momentum before and after the anomaly.

[0021] The three-axis orthogonal angular momentum synthesis method used in the relative angular momentum difference analysis or the whole-star angular momentum change analysis is replaced by other synthesis methods, including non-orthogonal synthesis methods.

[0022] The relative angular momentum difference analysis or whole-satellite angular momentum change analysis obtains interference torque by adding space environment torque detection or high-precision perturbation force analysis model, thereby improving the accuracy of calculation results.

[0023] The relative angular momentum difference analysis or whole-star angular momentum change analysis further improves the accuracy and scope of application of the method by increasing the elimination of measurement errors, calculating the confidence interval of the value, and accurately quantifying the judgment standard.

[0024] The beneficial effects of the present invention are:

[0025] 1) The problem of difficulty in separating the causes of abnormal instantaneous force on satellites is solved. The satellite angular momentum changes are calculated by two methods: relative angular momentum difference analysis and whole-satellite angular momentum change analysis, providing direct data basis for satellite anomaly positioning and source tracing analysis. The instantaneous force magnitude can be inferred based on the angular momentum calculation results.

[0026] 2) Compared with the method of using ground tests, simulations, etc. to infer the cause of anomalies, this invention improves the timeliness and efficiency of satellite instantaneous force anomaly analysis and positioning, and the calculation results are objective.

[0027] 3) Based on the cross-product relationship between the satellite angular momentum change vector and the force arm and force, the satellite angular momentum change vector can be used to infer the direction and route of the external force impact, providing support for further tracing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is the flow chart of the algorithm of the present invention.

[0029] Figure 2 It is a schematic diagram of the flywheel installation of the example of the present invention.

[0030] Figure 3 It is a schematic diagram of the rotation speed of the rotating parts of the example of the present invention.

[0031] Figure 4It is a schematic diagram of the angular velocity of a three-axis gyroscope according to a calculation example of the present invention.

[0032] Figure 5 It is a schematic diagram of the three-axis angular momentum of the satellite according to the calculation example of the present invention.

[0033] Figure 6 It is a schematic diagram of the synthetic angular momentum of the satellite according to the calculation example of the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The present invention includes but is not limited to the following embodiments.

[0035] Whether it is a collision or internal disintegration, the change in angular momentum must be instantaneous. During this instantaneous process, the satellite jet will not be connected to the control system for the time being, and the space environment torque on the satellite and the torque generated by the magnetic torquer can be ignored. This method uses the satellite gyro measurement output, flywheel speed, and other rotating parts speeds from the time the satellite is instantaneously subjected to force to before jet control as observation data, and proposes two analysis methods: relative angular momentum difference and whole satellite angular momentum change, to calculate the change in angular momentum before and after the satellite is instantaneously subjected to force. Figure 1 As shown, the specific calculation steps are as follows:

[0036] 1) Relative angular momentum difference analysis

[0037] When the satellite is abnormal, ignore the change in angular momentum caused by the short-term start-up of the flywheel, calculate and analyze the difference between the instantaneous change in angular momentum of the satellite's rotating parts and the change in angular momentum caused by the satellite's rotation, and determine whether the satellite is affected by external forces. Establish a satellite body angular momentum calculation model:

[0038] H sat_x =I xx ω x +I xy ω y +I xz ω z

[0039] H sat_y =I xy ω x +I yy ω y +I zy ω z

[0040]

[0041] Where I is the satellite's moment of inertia in all directions, and ω is the ground measurement value; x ,ω y ,ω z is the component of the satellite's inertial angular velocity in this system, which can be obtained through gyro combined telemetry.

[0042] The satellite body's synthetic angular momentum is:

[0043]

[0044] The change in the rotation speed of the satellite's rotating parts causes the conversion of the angular momentum of the entire satellite. The angular momentum of the rotating parts H ZD , establish the calculation model of the three-axis angular momentum of the rotating parts:

[0045] H ZD_x =I ZD_x ω ZD_x

[0046] H ZD_y =I ZD_y ω ZD_y

[0047] H ZD_z =I ZD_z ω ZD_z (3)

[0048] In the formula, I ZD is the moment of inertia of the rotating part, which is a known quantity; ω ZD To obtain the rotation speed of rotating parts and transmit telemetry parameters.

[0049] The synthetic angular momentum of the satellite's rotating parts is:

[0050]

[0051] Calculate the change in angular momentum:

[0052] H 差 =H sat_合 -H ZD_合 (5)

[0053] 2) Analysis of the change of angular momentum of the whole satellite

[0054] The angular momentum of the entire satellite is composed of the angular momentum of the star body, the angular momentum of the flywheel and the angular momentum of other rotating parts. The three-axis angular momentum of the satellite in this system is expressed as follows:

[0055] H=H sat +H wheel +H ZD (6)

[0056] In the formula, H sat is the satellite body angular momentum, H wheel is the flywheel angular momentum, H ZD is the angular momentum of other rotating parts. Among them, the angular momentum of the star H sat The components decomposed into each direction are:

[0057] H sat_x =Ixx ω x +I xy ω y +I xz ω z

[0058] H sat_y =I xy ω x +I yy ω y +I zy ω z

[0059] H sat_z =I xz ω x +I yz ω y +I zz ω z (7)

[0060] Where I is the satellite's moment of inertia in all directions, and ω is the ground measurement value; x ,ω y ,ω z is the component of the satellite's inertial angular velocity in this system, which can be obtained through gyro combined telemetry.

[0061] Total angular momentum of flywheel H wheel for:

[0062]

[0063] In the formula, I n is the moment of inertia of a certain flywheel, which is a known quantity; ω n_x ,ω n_y ,ω n_z They are the speed components of the nth flywheel in the X, Y, and Z axes, respectively, and are calculated from the flywheel speed telemetry and the known flywheel installation angle.

[0064] Angular momentum of rotating parts H ZD for:

[0065]

[0066] In the formula, I ZD is the moment of inertia of the rotating part, which is a known quantity; ω ZD To obtain the rotation speed of rotating parts and transmit telemetry parameters.

[0067] The above angular momentum is synthesized to get the angular momentum of the whole star. In this system, the components are:

[0068]

[0069] Three-axis composite angular momentum:

[0070]

[0071] The change of satellite angular momentum is calculated based on the calculation results of the three-axis composite angular momentum before and after the anomaly.

[0072] According to the principle of conservation of angular momentum, the change in angular momentum can be calculated using the above two methods. If the angular momentum of the satellite changes instantaneously, it can be determined that the satellite is subjected to instantaneous external force in space.

[0073] The model is a three-axis orthogonal angular momentum synthesis method. Other synthesis methods (such as non-orthogonal synthesis, etc.) can also be established according to actual applications. The angular momentum synthesis calculation items can also be improved based on this model.

[0074] The present invention ignores the interference of the space environment torque and the torque generated by the magnetic torquer when calculating the change of angular momentum, thereby simplifying the calculation model. Subsequently, the interference torque can be obtained by adding other space environment torque detection or high-precision perturbation force analysis models to improve the accuracy of the calculation results.

[0075] The present invention is mainly aimed at the analysis under the condition of large interference torque. Subsequently, the judgment criteria can be accurately quantified by adding methods such as eliminating measurement errors and calculating the confidence interval of the value, so as to further improve the accuracy and scope of application of the method.

[0076] The following takes a certain satellite as an example (hereinafter referred to as satellite Y) to give the implementation process.

[0077] 1. Determine the basic parameters of the satellite

[0078] During the on-orbit operation of satellite Y, the rotating parts on the satellite stopped rapidly, resulting in a serious abnormality of sudden attitude instability. In order to analyze the instantaneous force on the satellite, the basic parameters known to the satellite were first determined.

[0079] Step 1: Determine the installation positions of related stand-alone components, mainly including gyroscopes, flywheels, and rotating components.

[0080] 1) Fiber optic gyroscope. Assume that the directions of the orthogonal three-axis rate input axes of the fiber optic gyroscope are parallel to the three axes of the satellite's body coordinates (the fiber optic gyroscope X-axis is consistent with the X-axis direction of the satellite, the fiber optic gyroscope Z-axis is consistent with the Z-axis direction of the satellite, and the fiber optic gyroscope Y-axis is consistent with the Y-axis direction of the satellite).

[0081] 2) Flywheel combination. Assume that the satellite is equipped with 3 flywheels, 2 20Nms flywheels and 1 60Nms flywheel, and the installation method is as follows: Figure 1 As shown, the Z-axis angle of the Z-axis flywheel coordinate system is 10°.

[0082] 3) Assuming that the rotating parts on the satellite coincide with the +Z axis of the satellite system, angular momentum around the +Z axis is generated during normal clockwise rotation.

[0083] Step 2: Determine the moment of inertia of the satellite body, flywheel, and rotating parts.

[0084] 1) Assume that the satellite moment of inertia matrix I (kg·m 2 )for:

[0085]

[0086] 2) Assuming a flywheel inertia of 20 Nms wheel_20 (kg·m 2 )for:

[0087] I wheel_25 =0.04 (12)

[0088] 3) Assuming a flywheel inertia of 60 Nms wheel_60 (kg·m 2 )for:

[0089] I wheel_68 =0.1 (13)

[0090] 4) The direction of the satellite's rotating shaft coincides with the satellite's Z axis. Assume that its moment of inertia is I ZD (kg·m 2 )for:

[0091] I ZD =25 (14)

[0092] 2. Calculation of relative angular momentum difference

[0093] Step 1: Calculation condition analysis. When the satellite is normal, it is assumed that the rotation speed of the satellite's rotating parts is 120° / s. After the satellite anomaly occurs, the rotation speed of the satellite's rotating parts quickly drops to close to 0, and the satellite performs jet control after about 30 seconds. The angular momentum calculation condition analysis is as follows:

[0094] 1) The change in angular momentum must occur instantaneously;

[0095] 2) The output torque of the flywheel is small, and the angular momentum generated by the flywheel control is negligible when the rotating parts stop rotating;

[0096] 3) The moment the rotating parts stop rotating, the satellite has no jet control;

[0097] 4) Assuming there is no external torque, after the rotating part stops rotating, its rotational angular momentum is converted into the angular momentum of the star.

[0098] Step 2: Calculate the change of satellite angular momentum. The change of rotating parts speed and gyro angular velocity at abnormal time is as follows: Figure 2 , 3 shown.

[0099] According to the installation position of the rotating parts and formula (2), the angular momentum of the rotating parts at normal speed is 52.4Nms. After the rotating parts stop rotating, the gyro angular velocity [0.13, -0.5, 2.4] data is analyzed. According to formula (1), the angular momentum of the star is calculated to be 66.0Nms. The change in angular momentum is: H 差 =13.6Nms.

[0100] 3. Calculation of the difference in angular momentum of the entire star

[0101] Step 1: According to the installation information of the flywheel and rotating parts, determine the calculation model of the angular momentum of the flywheel and rotating parts. Calculation model of the angular momentum of the rotating parts:

[0102]

[0103] The calculation model of the total angular momentum of the flywheel is:

[0104]

[0105] In the formula, I wheel_20 ,I wheel_60 The moments of inertia of the 20Nms flywheel and the 60Nms flywheel are known quantities; ω x_wheel ,ω y_wheel ,ω z_wheel , are the rotational speeds of flywheels X, Y, and Z, respectively, which are obtained by remote measurement of flywheel speed.

[0106] Step 2: Synthesize the above angular momentum to get the angular momentum of the whole star, and the components in this system.

[0107] H x =I xx ω x +I xy ω y +I xz ω z +I wheel_20 ω x_wheel +I wheel_60 ω z_wheel sin(10°)

[0108] H y =I xy ω x +I yy ω y +I zy ω z +(-I wheel_20 ω y_wheel )

[0109] H z =I xz ω x +Iyz ω y +I zz ω z +I ZD ω ZD +I wheel_60 ω z_wheel sin(80°) (17)

[0110] Three-axis composite angular momentum:

[0111]

[0112] According to the satellite angular velocity, the angular momentum calculated by the flywheel speed, and the rotational angular momentum calculated by the rotating parts speed, the three-axis angular momentum and the synthetic angular momentum of the satellite system are calculated, such as Figure 4 , 5 shown.

[0113] 4. Analysis and application of calculation results

[0114] Before the satellite anomaly, the jet was not working, and the environmental interference torque (aerodynamic torque, solar pressure torque) and magnetic unloading torque in a short period of time can be ignored. When there is no external torque on the satellite, the components of the angular momentum of the system will change with the movement of the satellite in orbit, but the angular momentum of the whole satellite is conserved and the modulus of the angular momentum remains unchanged. Using the satellite's on-orbit telemetry data, two methods are used to calculate the sudden increase in the angular momentum of the whole satellite before and after the anomaly. Method 1 simplifies the calculation model, reduces the measurement error sources such as momentum wheels and jets, and can quickly estimate the change in angular momentum, but the random error is large; Method 2 analyzes the angular momentum of the whole satellite, and the relative error is small, but the calculation model is more complicated. From the calculation results, the modulus of the angular momentum before the anomaly is about 21Nms, and after the anomaly is about 35Nms, a change of 14Nms.

[0115] If it is an external collision, the momentum exchange caused by the satellite angular momentum change can be expressed as:

[0116] ΔH=r×Ft=r×mΔv (19)

[0117] Where △H is the satellite angular momentum increment, is the force arm, m is the mass of the object that undergoes momentum exchange, is the relative speed between the object undergoing momentum exchange and the satellite. From the above formula, we can see that the satellite angular momentum change vector and the force arm, the relative speed between the object undergoing momentum exchange and the satellite satisfy the cross product relationship, so the satellite angular momentum change vector is perpendicular to the force arm. Therefore, when the satellite center of mass is known, the plane where the momentum exchange point is located can be uniquely determined. The plane where the momentum exchange point is located can be calculated based on the center of mass position and the angular momentum change vector.

[0118] In summary, the present invention provides two methods for analyzing satellite instantaneous force anomalies based on the conservation of angular momentum. By analyzing the change of angular momentum, the magnitude and direction of the satellite force are inferred, which solves the problem of difficulty in separating the causes of satellite instantaneous force anomalies and provides direct data support for source tracing analysis.

Claims

1. A satellite instantaneous force anomaly analysis method based on angular momentum conservation, characterized in that: The following steps are involved: The angular momentum change is calculated by relative angular momentum difference analysis or whole-satellite angular momentum change analysis. If the satellite angular momentum changes instantaneously, it is determined that the satellite is subjected to an instantaneous external force in space. The relative angular momentum difference analysis is to calculate and analyze the difference between the instantaneous satellite rotating component angular momentum change and the angular momentum change caused by the satellite rotation. If the difference is not 0, it is determined that the satellite is subjected to an external force. The whole-satellite angular momentum change analysis is to combine the angular momentum of the star body, the angular momentum of the flywheel and the angular momentum of other rotating components into the whole-satellite angular momentum, and calculate the satellite angular momentum change according to the calculation results of the three-axis composite angular momentum before and after the anomaly.

2. The satellite instantaneous force anomaly analysis method based on angular momentum conservation according to claim 1 is characterized in that: The relative angular momentum difference comprises the following steps: The satellite body angular momentum calculation model is established as In the formula, H sat_x , H sat_y , H sat_z They represent the components of the satellite's angular momentum in each direction; I is the satellite's moment of inertia matrix in each direction, is the ground measurement value, and the subscripts represent the matrix elements; ω x ,ω y ,ω z is the component of the satellite's inertial angular velocity in each direction of the system, obtained through gyro combined telemetry; The satellite body's synthetic angular momentum is The change in the rotation speed of the satellite's rotating parts causes the transformation of the satellite's angular momentum, and a calculation model for the three-axis angular momentum of the rotating parts is established. In the formula, H ZD is the angular momentum of the rotating part, I ZD is the moment of inertia of the rotating part, ω ZD is the rotating parts speed; Composite angular momentum of satellite's rotating parts Calculate the change in angular momentum H 差 =H sat_合 -H ZD_合 .

3. The satellite instantaneous force anomaly analysis method based on angular momentum conservation according to claim 1 is characterized in that: The whole-star angular momentum change analysis comprises the following steps: Calculate the angular momentum H of the star sat Decompose into components in each direction Where I is the satellite's moment of inertia in all directions, and ω is the ground measurement value; x ,ω y ,ω z is the component of the satellite inertial angular velocity in this system, obtained through gyro combined telemetry; Calculate the total angular momentum of the flywheel In the formula, I n is the moment of inertia of a certain flywheel, ω n_x ,ω n_y ,ω n_z are the speed components of the nth flywheel in the three axes of X, Y and Z respectively; Calculating the angular momentum of a rotating part In the formula, I ZD is the moment of inertia of the rotating part, ω ZD is the rotating parts speed; The above angular momentum is combined to get the angular momentum of the whole star. In this system, each component is Then we can get the three-axis composite angular momentum The change of satellite angular momentum is calculated based on the calculation results of the three-axis composite angular momentum before and after the anomaly.

4. The satellite instantaneous force anomaly analysis method based on angular momentum conservation according to claim 1 is characterized in that: The three-axis orthogonal angular momentum synthesis method used in the relative angular momentum difference analysis or the whole-star angular momentum change analysis is replaced by other synthesis methods, including non-orthogonal synthesis methods.

5. The satellite instantaneous force anomaly analysis method based on angular momentum conservation according to claim 1 is characterized in that: The relative angular momentum difference analysis or whole-satellite angular momentum change analysis obtains interference torque by adding space environment torque detection or high-precision perturbation force analysis model, thereby improving the accuracy of calculation results.

6. The satellite instantaneous force anomaly analysis method based on angular momentum conservation according to claim 1 is characterized in that: The relative angular momentum difference analysis or whole-star angular momentum change analysis further improves the accuracy and scope of application of the method by increasing the elimination of measurement errors, calculating the confidence interval of the value, and accurately quantifying the judgment standard.

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