Discrete unloading method and device for large-scale assembly control moment gyroscope

Abstract

The embodiment of the invention relates to the technical field of spacecrafts, in particular to a discrete unloading method and device for a large-scale assembly control moment gyroscope. The method comprises the following steps: S1, calculating the angular momentum of a current control moment gyroscope needing to be unloaded; s2, judging whether the current angular momentum exceeds an unloading threshold value or not, and if yes, taking the current angular momentum as the angular momentum to be unloaded; s3, the jet system jets for a preset time in an on-satellite control period; s4, the unloading angular momentum of current injection unloading is calculated according to the preset injection time, the rotational inertia and the acceleration of the air injection system, and the angular momentum to be unloaded is updated according to the unloading angular momentum; and S5, judging whether the updated angular momentum to be unloaded is lower than a safety threshold value or not, if so, completing unloading, and if not, repeating the steps S3-S5 after a preset number of control periods. According to the scheme, the vibration of the flexible structure can be inhibited when the angular momentum of the control moment gyroscope is unloaded.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of spacecrafts, and particularly to a discrete unloading method and device for control moment gyroscopes of a large composite body. Background Art

[0002] Large payload operations required for the assembly of large composite bodies such as space stations will cause the momentum of the control moment gyroscopes providing attitude control to saturate. Therefore, thrusters need to be used to unload the control moment gyroscopes.

[0003] During the operation of the payload of a large composite body, the most fundamental problem is that the vibration of large flexible appendages on the spacecraft may be excited due to the long-term or periodic ignition of thrusters. After the control moment gyroscopes are saturated, jet unloading is required. In the design process of the jet system, it is necessary to avoid causing large impact loads on the structure and reduce flexible vibration. The jet unloading of ordinary spacecrafts all adopts a centralized jetting method or directly switches to the jet control mode to unload the angular momentum of the control moment gyroscopes. The traditional method does not consider the impact of unloading on the structure and flexible excitation. For large spacecrafts such as space stations, using the traditional method has great control risks. Summary of the Invention

[0004] The embodiments of the present invention provide a discrete unloading method, device, electronic device and storage medium for control moment gyroscopes of a large composite body, which can suppress the vibration of the flexible structure when unloading the angular momentum of the control moment gyroscopes.

[0005] In a first aspect, the present invention provides a discrete unloading method for control moment gyroscopes of a large composite body, including:

[0006] S1: Calculate the angular momentum that needs to be unloaded by the current control moment gyroscope;

[0007] S2: When it is determined whether the current angular momentum exceeds the unloading threshold, if it exceeds, use the current angular momentum as the angular momentum to be unloaded;

[0008] S3: The jet system jets for a preset time within one on-board control cycle;

[0009] S4: Calculate the unloading angular momentum of the current jet unloading according to the preset time, moment of inertia and acceleration of the jet system, and update the angular momentum to be unloaded according to the unloading angular momentum;

[0010] S5: Determine whether the updated angular momentum to be unloaded is lower than the safety threshold. If it is lower, the unloading is completed. If it is not lower, after an interval of a preset number of control cycles, repeat S3 - S5.

[0011] In a possible design, the preset time and the preset number are determined by the following method:

[0012] Select multiple undetermined times between the minimum injection time and the control period of the injection system;

[0013] Select multiple undetermined quantities;

[0014] Establish a pulse sequence according to the undetermined quantity, undetermined time, and control period. The pulse sequence consists of multiple repeated injection periods and interval periods; among them, the injection period is one control period, the injection duration within this control period is the undetermined time, the interval period is the number of undetermined control periods, and the injection system does not inject during the interval period;

[0015] Traverse each undetermined time and undetermined quantity to obtain multiple pulse sequences;

[0016] Simulate the power density under each pulse sequence;

[0017] When the power density is the lowest, determine the undetermined time and undetermined quantity in the pulse sequence as the preset time and preset quantity respectively.

[0018] In a possible design, the angular momentum is calculated by the following formula:

[0019] H needisat =(J all ([ω x ω y ω z T +C BO [0 ω0 0] T )

[0020] +[h CMGSumx h CMGSumy h CMGSumz T )

[0021] Among them, J all is the moment of inertia, [ω x ω y ω z T is the three-axis angular velocity of the celestial body, ω0 is the orbital angular velocity, C BO is the coordinate transformation matrix from the orbital coordinate system to the body coordinate system, [h CMGSumx h CMGSumy h CMGSumz T is the three-axis angular momentum of the control moment gyro, expressed within this system.

[0022] In a possible design, S4 is implemented by the following formula:

[0023] ​​​​

[0024] Among them, H DistUnloadCMD is the angular momentum to be unloaded, and C IB is the coordinate transformation matrix from the body coordinate system to the inertial coordinate system, and T jx , T jy , T jz are the preset times of jetting in three axial directions, a JS is the acceleration, and J all is the moment of inertia.

[0025] In a second aspect, the present invention provides a discrete unloading device for a large combined body control moment gyroscope, and the device includes:

[0026] The first unit is used to calculate the angular momentum that the current control moment gyroscope needs to be unloaded;

[0027] The second unit is used to judge whether the current angular momentum exceeds the unloading threshold. If it exceeds, the current angular momentum is used as the angular momentum to be unloaded;

[0028] The third unit is used to make the jetting system jet for a preset time within one on-star control period;

[0029] The fourth unit is used to calculate the unloading angular momentum unloaded in the current jet according to the preset time, moment of inertia and acceleration of the jetting system, and update the angular momentum to be unloaded according to the unloading angular momentum;

[0030] The fifth unit is used to judge whether the updated angular momentum to be unloaded is lower than the safety threshold. If it is lower, the unloading is completed. If it is not lower, after an interval of a preset number of control periods, the third unit is started.

[0031] In a possible design, the preset time and the preset number are determined by the following method:

[0032] Select a plurality of undetermined times between the minimum jetting time of the jetting system and the control period;

[0033] Select a plurality of undetermined numbers;

[0034] Establish a pulse sequence according to the undetermined number, undetermined time and control period. The pulse sequence is composed of multiple repeated jetting periods and interval periods; among them, the jetting period is one control period, and the jetting duration within this control period is the undetermined time, and the interval period is the undetermined number of control periods, and the jetting system does not jet within the interval period;

[0035] Traverse each undetermined time and undetermined number to obtain multiple pulse sequences;

[0036] Simulate the power density under each pulse sequence;

[0037] When the power density is the lowest, the undetermined time and undetermined quantity in the pulse sequence are respectively determined as the preset time and preset quantity.

[0038] In a possible design, the angular momentum is calculated by the following formula:

[0039] H needisat =(J all ([ω x ω y ω z T +C BO [0 ω0 0] T )

[0040] +[h CMGSumx h CMGSumy h CMGSumz T )

[0041] Wherein, J all is the moment of inertia, [ω x ω y ω z T is the triaxial angular velocity of the star body, ω0 is the orbital angular velocity, C BO is the coordinate transformation matrix from the orbital coordinate system to the body coordinate system, [h CMGSumx h CMGSumy h CMGSumz T is the triaxial angular momentum of the control moment gyro, expressed within this system.

[0042] In a possible design, S4 is implemented by the following formula:

[0043]

[0044] Wherein, H DistUnloadCMD is the angular momentum to be unloaded, C IB is the coordinate transformation matrix from the body coordinate system to the inertial coordinate system, T jx 、T jy 、T jz are the preset times of jetting in the three axis directions, a JS is the acceleration, J all is the moment of inertia.

[0045] Thirdly, an embodiment of the present invention further provides an electronic device, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the method of any embodiment of this specification is implemented.

[0046] ​​​​Fourthly, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed on a computer, the computer is made to execute the method according to any embodiment of this specification.

[0047] An embodiment of the present invention provides a discrete unloading method, device, electronic device and storage medium for a large combined body control moment gyro. By discretely designing the jet, that is, the jet system jets at intervals according to a preset pulse sequence, jet unloading is carried out while minimizing the vibration excitation of the flexible structure by the jet. Since the current unloading methods do not consider the flexible problem and there is excitation to the flexible structure during the unloading process, especially for large spacecraft, whose structural modal frequencies are low and are easily excited by the jet, this method can, while achieving the unloading target, design through the frequency and energy of the jet that can be ejected, and can effectively suppress the flexible structure, and can be applied and popularized to other flexible spacecraft. Description of the Drawings

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0049] Figure 1 It is a pulse width diagram of jet unloading provided by an embodiment of the present invention. Detailed Embodiments

[0050] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0051] The following describes the specific implementation manners of the above concepts.

[0052] The present invention provides a discrete unloading method for a large combined body control moment gyro, including:

[0053] S1: Calculate the angular momentum that needs to be unloaded by the current control moment gyro;

[0054] S2: When it is judged whether the current angular momentum exceeds the unloading threshold, if it exceeds, then use the current angular momentum as the angular momentum to be unloaded;

[0055] S3: The jet system jets for a preset time within one satellite control period;

[0056] S4: Calculate the angular momentum unloaded by the current jet according to the preset time of jetting by the jet system, the moment of inertia, and the acceleration, and update the angular momentum to be unloaded according to the unloaded angular momentum;

[0057] S5: Determine whether the updated angular momentum to be unloaded is lower than the safety threshold. If it is lower, the unloading is completed. If it is not lower, after an interval of a preset number of control periods, repeat S3 - S5.

[0058] Starting from the impact load on the structure during spacecraft jet unloading, by analyzing its frequency characteristics, this method links the energy of jet unloading with the vibration of the flexible structure of a large spacecraft, thereby realizing the vibration suppression of the flexible structure, and at the same time unloading the angular momentum of the spacecraft. This method essentially analyzes the influencing factors of the vibration of the flexible structure, designs the jet pulse width and interval, and achieves multiple purposes of unloading and vibration suppression, with novelty.

[0059] By effectively designing the jet pulse width, this method reduces the impact force of centralized jet control. On the one hand, it can reduce the impact interference of centralized jet on the structure, and on the other hand, it protects the attitude index, and can ensure a very high platform stability and accuracy during unloading. When the Chinese space station is in orbit application, during discrete unloading, the system stability index is maintained at the level of 0.01° / s. This method is different from the traditional centralized unloading method. It is a discrete unloading method in the basic strategy and is different from the traditional method in the basic idea, with creativity.

[0060] The information used in this method is the synthetic angular momentum of the satellite body, the control torque of the jet engine, and the frequency characteristics of the flexible structure. These indexes are all design data during the development of the spacecraft, and the data availability is good. Therefore, the jet strategy can be designed only on the ground and can be reflected as a normal control strategy of the spacecraft in the control system software, with good engineering feasibility and practicality.

[0061] In this embodiment, it can be realized by the following method to judge whether to start discrete jet unloading:

[0062] If the system angular momentum ||H needisat ||>ΔH1 UL (ΔH1 UL is the judgment threshold for CMG angular momentum unloading, that is, the unloading threshold), then set the unloading flag:

[0063] UnLoadMode_Dist=1;

[0064] Meanwhile, let:

[0065] HDistUnloadCMD = H needisat

[0066] H DistUnloadCMD Used to record the initial value of the angular momentum that needs to be unloaded this time.

[0067] If ||H needisat || · <ΔH2 UL (ΔH2 UL is the threshold for the completion of angular momentum unloading, that is, the safety threshold), then clear the unloading flag:

[0068] UnLoadMode_Dist = 0;

[0069] In some embodiments of the present invention, the preset time and the preset quantity are determined by the following method:

[0070] Select multiple pending times between the minimum injection time and the control period of the injection system;

[0071] Select multiple pending quantities;

[0072] Establish a pulse sequence according to the pending quantity, the pending time, and the control period. The pulse sequence consists of multiple repeated injection periods and interval periods; wherein, the injection period is one control period, the injection duration within this control period is the pending time, the interval period is the number of control periods of the pending quantity, and the injection system does not inject within the interval period;

[0073] Traverse each pending time and pending quantity to obtain multiple pulse sequences;

[0074] Simulate the power density under each pulse sequence;

[0075] When the power density is the lowest, determine the pending time and the pending quantity in the pulse sequence as the preset time and the preset quantity respectively.

[0076] Specifically, set the discrete jet time length Tmin, that is, the pending time, and the jet time interval between two jets N_Off_Step · ΔT, where ΔT is the on-board control period and N_Off_Step is the number of beats of the interval control period, that is, the pending quantity;

[0077] Design the jet time length and the jet interval according to the given vibration frequency of the flexible structure of the large composite body. The specific process is as follows:

[0078] Let u(t) be a pulse sequence of n pulses separated by n - 1 delay times N_Off_Step · ΔT, and the width of each jet pulse is Tmin, as Figure 1 shown.

[0079] To illustrate the relationship between the input signal and the power spectral density (PSD) of the induced load, it is assumed that a linear mapping y(s) = G(s)u(s) can be constructed from the thruster ignition input to the induced load variation.

[0080] Its mean square value or average power can be calculated from its power spectral function Φ yy (ω) through Equation (1):

[0081]

[0082] From the assumption, the input is a scalar, and the power spectral density of the output signal is as in Equation (2):

[0083] Φ yy (ω) = G(jω)Φ uu (ω)G * (jω) (2)

[0084] This equation establishes the relationship between the power spectral density of the input pulse and the mean value of the induced load.

[0085] The design objective is to select an appropriate delay time to minimize the vibration of the flexible attachment caused by the jet within a certain frequency range.

[0086] The upper bound maximum value is selected to minimize the power density at the characteristic frequency:

[0087]

[0088] Therefore, to minimize the average energy of the output signal of any (stable) system dynamics, it is necessary to minimize the maximum value of the amplitude of the power spectral density of the input signal.

[0089] Thus, the problem of optimal design within a specific frequency range [ω1, ω2] can be described as:

[0090]

[0091] The conditions are:

[0092] a) The total opening time of the thruster is fixed;

[0093] b) The total delay time is fixed;

[0094] c) The variation range of the delay time is fixed.

[0095] The method given by Equation (4) is called the energy-optimal pulse control method.

[0096] It is noted that the input signal power density spectrum is a function of the delay time N_Off_Step·ΔT and the magnitude Tmin, which can be determined by a reasonable selection of N_Off_Step and Tmin.

[0097] Such a selection can maximize the energy uniformity of the selected bandwidth and reduce the energy concentration at any characteristic frequency. This pulse mode can minimize the power density peak within a specific frequency range and minimize the excitation of the vibration of the system's flexible appendages.

[0098] Thus far, the discrete jet preset time Tmin and the number of steps (preset quantity) of the jet time interval between two jets, N_Off_Step, have been obtained.

[0099] In some embodiments of the present invention, the angular momentum is calculated by the following formula:

[0100] H needisat =(J all ([ω x ω y ω z T +C BO [0 ω0 0] T )

[0101] +[h CMGSumx h CMGSumy h CMGSumz T )

[0102] Wherein, J all is the moment of inertia, [ω x ω y ω z T is the three-axis angular velocity of the star body, ω0 is the orbital angular velocity, C BO is the coordinate transformation matrix from the orbital coordinate system to the body coordinate system, [h CMGSumx h CMGSumy h CMGSumz T is the three-axis angular momentum of the control moment gyro, expressed within this system.

[0103] In some embodiments of the present invention, S4 is implemented by the following formula:

[0104]

[0105] Wherein, H DistUnloadCMD is the angular momentum to be unloaded, C IB is the coordinate transformation matrix from the body coordinate system to the inertial coordinate system, T jx 、T jy ​​​​, T jz is the preset time for jetting in three axial directions, a JS is the acceleration, J all is the moment of inertia.

[0106] In a second aspect, the present invention provides a discrete unloading device for a large combined control moment gyroscope, the device comprising:

[0107] A first unit for calculating the angular momentum that the current control moment gyroscope needs to be unloaded;

[0108] A second unit for determining whether the current angular momentum exceeds the unloading threshold, and if it exceeds, taking the current angular momentum as the angular momentum to be unloaded;

[0109] A third unit for the jet system to jet for a preset time within one on-star control period;

[0110] A fourth unit for calculating the unloading angular momentum of the current jetting unloading according to the preset time, moment of inertia and acceleration of the jet system, and updating the angular momentum to be unloaded according to the unloading angular momentum;

[0111] A fifth unit for determining whether the updated angular momentum to be unloaded is lower than the safety threshold. If it is lower, the unloading is completed. If it is not lower, after an interval of a preset number of control periods, the third unit is started.

[0112] In some embodiments of the present invention, the preset time and the preset number are determined by the following method:

[0113] Select a plurality of pending times between the minimum jetting time of the jetting system and the control period;

[0114] Select a plurality of pending numbers;

[0115] Establish a pulse sequence according to the pending number, pending time and control period. The pulse sequence consists of repeated multiple groups of jetting periods and interval periods; wherein, the jetting period is one control period, the jetting duration within this control period is the pending time, the interval period is the pending number of control periods, and the jetting system does not jet within the interval period;

[0116] Traverse each pending time and pending number to obtain a plurality of pulse sequences;

[0117] Simulate the power density under each pulse sequence;

[0118] When the power density is the lowest, determine the pending time and pending number in the pulse sequence as the preset time and preset number respectively.

[0119] In some embodiments of the present invention, the angular momentum is calculated by the following formula:

[0120] Hneedisat =(J all ([ω x ω y ω z ) T +C BO [0 ω0 0] T )

[0121] +[h CMGSumx h CMGSumy h CMGSumz ) T )

[0122] where J all is the moment of inertia, [ω x ω y ω z is the triaxial angular velocity of the celestial body, ω0 is the orbital angular velocity, C T is the coordinate transformation matrix from the orbital coordinate system to the body coordinate system, [h BO h CMGSumx h CMGSumy h CMGSumz is the triaxial angular momentum of the control moment gyro, expressed in this system. T

[0123] In some embodiments of the present invention, S4 is implemented by the following formula:

[0124]

[0125] where H DistUnloadCMD is the angular momentum to be unloaded, C IB is the coordinate transformation matrix from the body coordinate system to the inertial coordinate system, T jx , T jy , T jz are the preset times of injection in the three axis directions, a JS is the acceleration, and J all is the moment of inertia.

[0126] ​An embodiment of the present invention provides a discrete unloading device for a large combined body control moment gyroscope. The device embodiment can be implemented by software, or by hardware or a combination of software and hardware. At the hardware level, it is a hardware architecture diagram of an electronic device where the discrete unloading device for a large combined body control moment gyroscope provided by the embodiment of the present invention is located. In addition to a processor, a memory, a network interface, and a non-volatile memory, the electronic device where the device is located in the embodiment usually may also include other hardware, such as a forwarding chip responsible for processing messages, etc. Taking software implementation as an example, as a device in a logical sense, it is formed by reading a corresponding computer program in the non-volatile memory into the memory and running it through the CPU of its electronic device. The discrete unloading device for a large combined body control moment gyroscope provided by this embodiment includes:

[0127] A first unit for calculating the angular momentum that needs to be unloaded by the current control moment gyroscope;

[0128] A second unit for determining whether the current angular momentum exceeds the unloading threshold. If it exceeds, the current angular momentum is used as the angular momentum to be unloaded;

[0129] A third unit for the jet system to jet for a preset time within one on-board control cycle;

[0130] A fourth unit for calculating the unloading angular momentum unloaded by the current jet according to the preset time, moment of inertia, and acceleration of the jet system, and updating the angular momentum to be unloaded according to the unloading angular momentum;

[0131] A fifth unit for determining whether the updated angular momentum to be unloaded is lower than the safety threshold. If it is lower, the unloading is completed. If it is not lower, after an interval of a preset number of control cycles, the third unit is started.

[0132] In some embodiments of the present invention, the preset time and the preset number are determined by the following method:

[0133] Select multiple pending times between the minimum jet time of the jet system and the control cycle;

[0134] Select multiple pending numbers;

[0135] Establish a pulse sequence according to the pending number, pending time, and control cycle. The pulse sequence consists of multiple repeated jetting cycles and interval cycles; among them, the jetting cycle is one control cycle, the jetting duration within this control cycle is the pending time, the interval cycle is the pending number of control cycles, and the jet system does not jet within the interval cycle;

[0136] Traverse each pending time and pending number to obtain multiple pulse sequences;

[0137] Simulate and analyze the power density under each pulse sequence;

[0138] When the power density is the lowest, the undetermined time and undetermined quantity in the pulse sequence are respectively determined as the preset time and preset quantity.

[0139] In some embodiments of the present invention, the angular momentum is calculated by the following formula:

[0140] H needisat =(J all ([ω x ω y ω z ) T +C BO [0 ω0 0] T )

[0141] +[h CMGSumx h CMGSumy h CMGSumz ) T )

[0142] where J all is the moment of inertia, [ω x ω y ω z T is the triaxial angular velocity of the star, ω0 is the orbital angular velocity, C BO is the coordinate transformation matrix from the orbital coordinate system to the body coordinate system, [h CMGSumx h CMGSumy h CMGSumz T is the triaxial angular momentum of the control moment gyro, expressed within this system.

[0143] In some embodiments of the present invention, S4 is implemented by the following formula:

[0144]

[0145] where H DistUnloadCMD is the angular momentum to be unloaded, C IB is the coordinate transformation matrix from the body coordinate system to the inertial coordinate system, T jx , T jy , T jz are the preset times of jetting in the three axis directions, a JS is the acceleration, and J all is the moment of inertia.

[0146] It is understandable that the structure illustrated in the embodiments of the present invention does not constitute a specific limitation on a discrete unloading device for a large combined body control moment gyroscope. In other embodiments of the present invention, a discrete unloading device for a large combined body control moment gyroscope may include more or fewer components than those illustrated, or combine certain components, or split certain components, or have different component arrangements. The illustrated components can be implemented in hardware, software, or a combination of software and hardware.

[0147] Regarding the information interaction, execution process, etc. between the various modules within the above-mentioned device, since they are based on the same concept as the method embodiments of the present invention, the specific content can be referred to the descriptions in the method embodiments of the present invention and will not be elaborated here.

[0148] The embodiments of the present invention also provide an electronic device, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, it implements a discrete unloading method for a large combined body control moment gyroscope in any embodiment of the present invention.

[0149] The embodiments of the present invention also provide a computer-readable storage medium. A computer program is stored on the computer-readable storage medium. When the computer program is executed by a processor, the processor is enabled to execute a discrete unloading method for a large combined body control moment gyroscope in any embodiment of the present invention.

[0150] Specifically, a system or device equipped with a storage medium can be provided. Software program code for implementing the functions in any of the above embodiments is stored on the storage medium, and the computer (or CPU or MPU) of the system or device reads and executes the program code stored on the storage medium.

[0151] In this case, the program code read from the storage medium itself can implement the functions of any one of the above embodiments. Therefore, the program code and the storage medium storing the program code constitute a part of the present invention.

[0152] Embodiments of the storage medium for providing program code include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), magnetic tapes, non-volatile memory cards, and ROMs. Optionally, the program code can be downloaded from a server computer via a communication network.

[0153] Furthermore, it should be clear that not only can the actual operations be completed in part or in whole by executing the program code read by the computer, but also by the operating system operating on the computer based on the instructions of the program code, so as to implement the functions of any one of the above embodiments.

[0154] In addition, it can be understood that the program code read from the storage medium is written into the memory provided in the expansion board inserted into the computer or into the memory provided in the expansion module connected to the computer. Subsequently, based on the instructions of the program code, the CPU etc. installed on the expansion board or the expansion module are made to execute part or all of the actual operations, thereby implementing the functions of any one of the above embodiments.

[0155] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0156] Those of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps including the above method embodiments; and the aforementioned storage medium includes various media such as ROM, RAM, magnetic disk or optical disc that can store program code.

[0157] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A discrete unloading method for a large combined control moment gyroscope, characterized in that, Including: S1: Calculate the angular momentum that the current control moment gyro needs to be unloaded. S2: When it is judged whether the current angular momentum exceeds the unloading threshold, if it exceeds, use the current angular momentum as the angular momentum to be unloaded. S3: The jet system jets for a preset time within one on-orbit control period. S4: Calculate the unloading angular momentum unloaded by the current jet according to the preset time, moment of inertia and acceleration of the jet system, and update the angular momentum to be unloaded according to the unloading angular momentum. S5: Judge whether the updated angular momentum to be unloaded is lower than the safety threshold. If it is lower, the unloading is completed. If it is not lower, after an interval of a preset number of control periods, repeat S3 - S5.

2. The method according to claim 1, wherein The preset time and the preset number are determined by the following method: Select multiple pending times between the minimum jet time of the jet system and the control period. Select multiple pending numbers. Establish a pulse sequence according to the pending number, pending time and control period. The pulse sequence consists of multiple repeated jet periods and interval periods; among them, the jet period is one control period, the jet duration within this control period is the pending time, the interval period is the pending number of control periods, and the jet system does not jet during the interval period. Traverse each pending time and pending number to obtain multiple pulse sequences. Simulate the power density under each pulse sequence. When the power density is the lowest, determine the pending time and pending number in the pulse sequence as the preset time and preset number respectively.

3. The method according to claim 1, characterized in that, The angular momentum is calculated by the following formula: H needisat = (J all ([ω x ω y ω z T + C BO [0 ω0 0] T ) + [h CMGSumx h CMGSumy h CMGSumz T )​​ Among them, J all is the moment of inertia, [ω x ω y ω z T is the three-axis angular velocity of the celestial body, ω0 is the orbital angular velocity, C BO is the coordinate transformation matrix from the orbital coordinate system to the body coordinate system, [h CMGSumx h CMGSumy h CMGSumz T is the three-axis angular momentum of the control moment gyro, expressed within this system.​​ 4. The method according to claim 1, wherein S4 is implemented by the following formula: Among them, H DistUnloadCMD is the angular momentum to be unloaded, C IB is the coordinate transformation matrix from the body coordinate system to the inertial coordinate system, T jx 、T jy 、T jz are the preset times of jetting in the three axis directions, a JS is the acceleration, J all is the moment of inertia.

5. A discrete unloading device for a large combined body control moment gyroscope, characterized in that, The device includes: The first unit is used to calculate the angular momentum that the current control moment gyro needs to be unloaded. The second unit is used to judge whether the current angular momentum exceeds the unloading threshold. If it exceeds, use the current angular momentum as the angular momentum to be unloaded. The third unit is used to make the jet system jet for a preset time within one on-orbit control period. The fourth unit is used to calculate the unloading angular momentum unloaded by the current jet according to the preset time, moment of inertia and acceleration of the jet system, and update the angular momentum to be unloaded according to the unloading angular momentum. The fifth unit is used to judge whether the updated angular momentum to be unloaded is lower than the safety threshold. If it is lower, the unloading is completed. If it is not lower, after an interval of a preset number of control periods, start the third unit.

6. The method according to claim 5, characterized in that The preset time and the preset number are determined by the following method: Select multiple pending times between the minimum jet time of the jet system and the control period. Select multiple pending numbers. Establish a pulse sequence according to the pending number, pending time and control period. The pulse sequence consists of multiple repeated jet periods and interval periods; among them, the jet period is one control period, the jet duration within this control period is the pending time, the interval period is the pending number of control periods, and the jet system does not jet during the interval period. Traverse each pending time and pending number to obtain multiple pulse sequences. Simulate the power density under each pulse sequence. When the power density is the lowest, determine the pending time and pending number in the pulse sequence as the preset time and preset number respectively.

7. The method according to claim 5, characterized in that, The angular momentum is calculated by the following formula: H needisat = (J all ([ω x ω y ω z ) T + C BO [0 ω0 0] T ) + [h CMGSumx h CMGSumy h CMGSumz ) T ) Among them, J all is the moment of inertia, [ω x ω y ω z T is the three-axis angular velocity of the celestial body, ω0 is the orbital angular velocity, C BO is the coordinate transformation matrix from the orbital coordinate system to the body coordinate system, [h CMGSumx h CMGSumy h CMGSumz T is the three-axis angular momentum of the control moment gyro, expressed within this system.​​ 8. The method according to claim 5, characterized in that, S4 is implemented by the following formula: Among them, H DistUnloadCMD is the angular momentum to be unloaded, C IB is the coordinate transformation matrix from the body coordinate system to the inertial coordinate system, T jx 、T jy 、T jz are the preset times of jetting in the three axis directions, a JS is the acceleration, J all is the moment of inertia.

9. An electronic device, comprising a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the method according to any one of claims 1-4 is implemented.

10. A computer-readable storage medium, on which a computer program is stored. When the computer program is executed in a computer, the computer is caused to execute the method according to any one of claims 1-4.

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