Large flexible accessory disturbance force estimation method based on ground test data

Abstract

The invention discloses a large-scale flexible accessory disturbance force estimation method based on ground test data, and the method comprises the steps: selecting a segmentation frequency point according to a fundamental frequency f0, and dividing the full frequency range of a large-scale flexible accessory to be subjected to disturbance force estimation into a low frequency band and a high frequency band; measuring disturbing force when the driving motor is in a no-load state to obtain FAong (f); respectively establishing finite element models of a driving motor no-load state and a large flexible accessory state, and determining internal virtual disturbing force nodes and disturbing force output nodes in the two states; transfer characteristic simulation is carried out, and FRFAong (f) and FRFLoad (f) are obtained; and estimating the disturbance force of the large flexible accessory based on the divided low-frequency band and high-frequency band in combination with FAong (f), FRFAong (f) and FRFLoad (f). According to the method disclosed by the invention, the disturbance force estimated value of the driving motor for driving the large flexible accessory, which is suitable for engineering practice, can be given by utilizing the ground measured data of the disturbance force of the driving motor without load and the transfer characteristics obtained by finite element simulation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of spacecraft dynamics analysis and test technology, and particularly relates to a large flexible accessory disturbance force estimation method based on ground test data. BACKGROUND

[0002] During the on-orbit operation of a spacecraft, normal operation of moving parts thereon or slight excitation of the space environment and other factors can cause the spacecraft to produce a small-amplitude reciprocating motion, i.e., micro-vibration of the spacecraft, and the normal operation of moving parts or slight excitation of the space environment and other factors are referred to as disturbance sources. The micro-vibration phenomenon of the spacecraft can affect the normal use of high-precision pointing equipment on the spacecraft, such as laser communication payloads, optical remote sensing cameras, and the like, thereby directly affecting the success or failure of the system mission. With the increasing requirement of spacecraft payloads for high-precision pointing, micro-vibration analysis and design have become one of the key technologies of spacecraft design.

[0003] The engineering implementation process of spacecraft micro-vibration analysis and design includes micro-vibration environment requirement analysis, micro-vibration disturbance source disturbance force testing and modeling, micro-vibration structure transfer characteristic analysis, multi-level micro-vibration suppression scheme design, micro-vibration ground measurement test, and micro-vibration on-orbit measurement. Among them, the testing and modeling of the disturbance forces of various disturbance sources on the spacecraft is one of the key steps of spacecraft micro-vibration analysis and design.

[0004] Existing researches have shown that typical disturbance forces of the spacecraft during on-orbit operation include momentum wheels, control moment gyroscopes, solar wing driving mechanisms, antenna pointing mechanisms, and thrusters. Among them, the solar wing driving mechanism and the antenna pointing mechanism both belong to the combined disturbance of driving motors and large flexible accessories. Since typical large flexible accessories such as solar wings and deployable antennas are difficult to be directly deployed under the gravity environment due to their large structure, large flexibility, large mass / inertia, and small damping, it is very difficult or even impossible to directly measure the disturbance force of the driving motor driving the large flexible accessory through ground test. At the same time, there is no mature method for high-precision simulation of the disturbance force of the driving motor driving the large flexible accessory. The existing theoretical modeling method only considers the disturbance force of the driving motor and the large flexible accessory rotating around the rotating axis, and ignores the disturbance forces of the remaining five degrees of freedom, which cannot be directly applied in engineering. Therefore, it is necessary to propose a simple and reliable disturbance force estimation method for the spacecraft driving motor driving the large flexible accessory suitable for engineering practice. SUMMARY

[0005] The technical problem solved by the present application is to overcome the shortcomings of the prior art and provide a large flexible accessory disturbance force estimation method based on ground test data, which can utilize the disturbance force ground test data of the driving motor in no-load state and the transfer characteristics obtained by finite element simulation to give the disturbance force estimation value of the driving motor driving the large flexible accessory suitable for engineering practice.

[0006] To solve the above technical problems, the present application discloses a large flexible accessory disturbance force estimation method based on ground test data, comprising:

[0007] The full frequency range of the large flexible accessory to be estimated for disturbance force is divided into a low frequency band and a high frequency band according to the fundamental frequency f0 of the fixed boundary state of the large flexible accessory to be estimated for disturbance force;

[0008] The disturbance force of the driving motor in no-load state is measured to obtain F Along (f); wherein F Along (f) represents a vector composed of the frequency domain response data of the disturbance force and torque of the driving motor in no-load state, and f represents the frequency;

[0009] The finite element models of the driving motor in no-load state and with large flexible accessory are respectively established, and the internal virtual disturbance force nodes and disturbance force output nodes in the two states of the driving motor in no-load state and with large flexible accessory are determined;

[0010] The transfer characteristic simulation is carried out to obtain FRF Along (f) and FRF Load (f); wherein FRF Along (f) represents a matrix composed of the force and torque transfer functions from the internal virtual disturbance force nodes to the disturbance force output nodes when the driving motor is in no-load state, and FRF Load (f) represents a matrix composed of the force and torque transfer functions from the internal virtual disturbance force nodes to the disturbance force output nodes when the driving motor is with large flexible accessory;

[0011] Based on the divided low frequency band and high frequency band, combined with F Along (f), FRF Along (f) and FRF Load (f), the disturbance force of the large flexible accessory is estimated to obtain the disturbance force estimation result.

[0012] In the above large flexible accessory disturbance force estimation method based on ground test data, if f A , it is divided into a low frequency band; if f A , it is divided into a high frequency band; wherein f A represents the frequency of the division frequency point.

[0013] In the large flexible appendage disturbance force estimation method based on ground test data, f A > 2f0.

[0014] In the large flexible appendage disturbance force estimation method based on ground test data, the disturbance force of the driving motor in the no-load state is measured, and F Along (f) comprises:

[0015] The time-domain response data of the three-direction disturbance force and torque of the driving motor for driving the large flexible appendage in the no-load state is measured using a six-component force platform;

[0016] The time-domain response data of the three-direction disturbance force and torque of the driving motor for driving the large flexible appendage in the no-load state is measured using a six-component force platform; Along (f) is obtained by frequency domain conversion.

[0017] In the large flexible appendage disturbance force estimation method based on ground test data, the sampling frequency of the time-domain response data of the disturbance force and torque is greater than twice the upper limit of the disturbance force estimation frequency range.

[0018] In the large flexible appendage disturbance force estimation method based on ground test data, finite element models of the driving motor in the no-load and large flexible appendage states are established respectively, and internal virtual disturbance force nodes and disturbance force output nodes in the driving motor in the no-load and large flexible appendage states are determined, comprising:

[0019] A first finite element model of the driving motor in the no-load state is established; in the first finite element model, a multi-point constraint unit MPC is used to connect the edge nodes of the rotating shaft of the driving motor in the first finite element model with the center of the rotating shaft, as internal virtual disturbance force nodes in the no-load state of the driving motor; the nodes of the driving motor and the spacecraft connection interface in the first finite element model are connected, as disturbance force output nodes in the no-load state of the driving motor;

[0020] A second finite element model of the driving motor in the large flexible appendage state is established; in the second finite element model, a multi-point constraint unit MPC is used to connect the edge nodes of the rotating shaft of the driving motor in the second finite element model with the center of the rotating shaft, as internal virtual disturbance force nodes in the large flexible appendage state; the nodes of the driving motor and the spacecraft connection interface in the second finite element model are connected, as disturbance force output nodes in the large flexible appendage state.

[0021] In the large flexible accessory disturbance force estimation method based on ground test data, the driving motor part in the first finite element model is completely consistent with the driving motor part in the second finite element model; the internal virtual disturbance force node in the first finite element model is completely consistent with the internal virtual disturbance force node in the second finite element model; and the disturbance force output node in the first finite element model is completely consistent with the disturbance force output node in the second finite element model.

[0022] In the large flexible accessory disturbance force estimation method based on ground test data, the transfer characteristic simulation is carried out to obtain FRF Along (f) and FRF Load (f) include:

[0023] The frequency response analysis in the low frequency range is carried out in the first finite element model, and the three-direction unit disturbance force and torque are sequentially applied to the internal virtual disturbance force node in the no-load state of the driving motor to obtain the force and torque transfer function from the internal virtual disturbance force node in the no-load state of the driving motor to the disturbance force output node in the no-load state of the driving motor, and then the FRF Along (f) is obtained.

[0024] The frequency response analysis in the low frequency range is carried out in the second finite element model, and the three-direction unit disturbance force and torque are sequentially applied to the internal virtual disturbance force node in the state of the large flexible accessory to obtain the force and torque transfer function from the internal virtual disturbance force node in the state of the large flexible accessory to the disturbance force output node in the state of the large flexible accessory, and then the FRF Load (f) is obtained.

[0025] In the large flexible accessory disturbance force estimation method based on ground test data, based on the divided low frequency range and high frequency range, the disturbance force of the large flexible accessory is estimated in combination with F Along (r), FRF Along (r) and FRF Load (r) to obtain the disturbance force estimation result, including:

[0026] When f≤f A , there is:

[0027] [F Load (r)]=[FRF Load (r)]·[FRF Along (r)] -1 ·[F Along (r)]

[0028] When f>f A , there is:

[0029] [F Load (r)]≈[FAlong (f)]

[0030] wherein, [F Load (f)] represents the disturbance force estimation result.

[0031] In the large flexible appendage disturbance force estimation method based on ground test data, the rotation rate of the driving motor in the no-load state is consistent with the common rotation rate of the driving motor in driving the large flexible appendage in orbit.

[0032] The present application has the following advantages:

[0033] The present application discloses a large flexible appendage disturbance force estimation method based on ground test data, which divides the full frequency band of disturbance force estimation into a low frequency band and a high frequency band, estimates the disturbance force of the driving motor driving the large flexible appendage in the low frequency band by assuming that there is a constant virtual disturbance force in the driving motor, and further estimates the disturbance force of the driving motor driving the large flexible appendage according to the ground measured disturbance force of the driving motor in the no-load state and the vibration transfer characteristics obtained by simulation, and directly uses the ground measured disturbance force of the driving motor in the no-load state for approximation in the high frequency band. In this way, the technical scheme provided by the present application can obtain the engineering usable disturbance force estimation value of the driving motor driving the large flexible appendage in orbit by using the disturbance force data of the driving motor measured in the no-load state on the ground and the vibration transfer characteristics of the driving motor and the large flexible appendage, thereby avoiding the problems of difficulty in direct ground measurement, lack of high-precision simulation method, and imperfect theoretical model, and can be used for spacecraft micro-vibration analysis and design. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a flowchart of a large flexible appendage disturbance force estimation method based on ground test data in an embodiment of the present application. DETAILED DESCRIPTION

[0035] To make the purpose, technical scheme and advantages of the present application clearer, the following will further describe the disclosed embodiments of the present application in combination with the drawings.

[0036] One of the core ideas of the present application is that, in view of the deficiencies in the prior art that the disturbance force of the driving motor driving the large flexible appendage on the spacecraft is difficult to measure directly on the ground, high-precision simulation methods are lacking, and theoretical models are not perfect enough to be directly applied in engineering, the present application provides a large flexible appendage disturbance force estimation method based on ground test data, which can use the ground measured disturbance force data of the driving motor in the no-load state and the transfer characteristics obtained by finite element simulation to give the disturbance force estimation value of the driving motor driving the large flexible appendage suitable for engineering practice.

[0037] Reference Figure 1 In the present embodiment, the large flexible appendage disturbance force estimation method based on ground test data comprises:

[0038] Step 1, select a division frequency point according to the fundamental frequency f0 of the fixed boundary state of the large flexible accessory to be disturbed force estimated, and divide the full frequency range of the large flexible accessory to be disturbed force estimated into a low frequency band and a high frequency band.

[0039] In this embodiment, if f≤f A , it is divided into a low frequency band; if f>f A , it is divided into a high frequency band. Wherein, f represents the frequency; f A represents the frequency of the division frequency point, and f A >2f0.

[0040] Step 2, measure the disturbance force of the driving motor under no load to obtain F Along (f).

[0041] In this embodiment, the six-component force platform can be used to measure the time domain response data of the three-direction disturbance force and torque of the driving motor for driving the large flexible accessory under no load; then, the measured time domain response data of the three-direction disturbance force and torque of the driving motor for driving the large flexible accessory under no load is converted into frequency domain to obtain the frequency domain response data of the disturbance force and torque of the driving motor under no load, and then obtain F Along (f). Wherein, F Along (f) represents a vector composed of the frequency domain response data of the disturbance force and torque of the driving motor under no load; the sampling frequency of the time domain response data of the disturbance force and torque is greater than 2 times the upper limit of the disturbance force estimation frequency range; the rotation rate of the driving motor under no load is consistent with the common rotation rate of the driving motor driving the large flexible accessory on the track, if the common rotation rate of the driving motor driving the large flexible accessory on the track has multiple, it should be measured and estimated respectively.

[0042] Step 3, respectively establish the finite element models of the driving motor under no load and with large flexible accessory, and determine the internal virtual disturbance force nodes and disturbance force output nodes under the two states of the driving motor under no load and with large flexible accessory.

[0043] In the embodiment, a first finite element model of the driving motor in an idle state and a second finite element model of the driving motor with a large flexible accessory can be respectively established. Further, in the first finite element model, a multi-point constraint unit MPC (Multi-Point Constraint, MPC) is used to connect the edge nodes of the rotating shaft of the driving motor in the first finite element model with the center of the rotating shaft, as internal virtual disturbance force nodes in the idle state of the driving motor; the interface nodes of the driving motor and the spacecraft in the first finite element model are connected, as disturbance force output nodes in the idle state of the driving motor. In the second finite element model, a multi-point constraint unit MPC is used to connect the edge nodes of the rotating shaft of the driving motor in the second finite element model with the center of the rotating shaft, as internal virtual disturbance force nodes in the state of the driving motor with a large flexible accessory; the interface nodes of the driving motor and the spacecraft in the second finite element model are connected, as disturbance force output nodes in the state of the driving motor with a large flexible accessory. The driving motor part in the first finite element model is completely consistent with the driving motor part in the second finite element model; the internal virtual disturbance force nodes in the first finite element model are completely consistent with the internal virtual disturbance force nodes in the second finite element model; the disturbance force output nodes in the first finite element model are completely consistent with the disturbance force output nodes in the second finite element model.

[0044] Step 4, carry out transfer characteristic simulation to obtain FRF Along (f). Load (f).

[0045] In the embodiment, transfer characteristic simulation in the idle state of the driving motor and the state of the driving motor with a large flexible accessory can be respectively carried out based on the first finite element model and the second finite element model:

[0046] In the first finite element model, frequency response analysis in a low-frequency range is carried out, and three-direction unit disturbance forces and torques are sequentially applied to the internal virtual disturbance force nodes in the idle state of the driving motor, to obtain force and torque transfer functions from the internal virtual disturbance force nodes in the idle state of the driving motor to the disturbance force output nodes in the idle state of the driving motor, and further to obtain FRF Along (f). Wherein, FRF Along (f) represents a matrix composed of force and torque transfer functions from the internal virtual disturbance force nodes to the disturbance force output nodes in the idle state of the driving motor.

[0047] In the second finite element model, frequency response analysis in a low-frequency range is carried out, and three-direction unit disturbance forces and torques are sequentially applied to the internal virtual disturbance force nodes in the state of the driving motor with a large flexible accessory, to obtain force and torque transfer functions from the internal virtual disturbance force nodes in the state of the driving motor with a large flexible accessory to the disturbance force output nodes in the state of the driving motor with a large flexible accessory, and further to obtain FRF Load(f). Wherein, FRF Load (f) represents a matrix composed of force and moment transfer functions from the internal virtual disturbance force node to the disturbance force output node when the large flexible appendage is attached.

[0048] Step 5, based on the divided low frequency band and high frequency band, combining F Along (f), FRF Along (f) and FRF Load (f), the disturbance force of the large flexible appendage is estimated to obtain the disturbance force estimation result.

[0049] In the embodiment, when the disturbance force estimation of the large flexible appendage is performed, it can be divided into two parts of low frequency band and high frequency band to estimate respectively:

[0050] When f≤f A , there is:

[0051] [F Load (f) ] = [FRF Load (f) ] · [FRF Along (f) ] -1 · [F Along (f) ]

[0052] When f>f A , there is:

[0053] [F Load (f) ] ≈ [F Along (f) ]

[0054] Wherein, [F Load (f) ] represents the disturbance force estimation result.

[0055] Although the present application has been disclosed with the above preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not depart from the technical solutions of the present application, shall fall within the protection scope of the technical solutions of the present application.

[0056] The contents not described in detail in the specification of the present application belong to the known technology of the person skilled in the art.

Claims

1. A method for estimating the disturbance force of a large flexible attachment based on ground test data, characterized in that: include: Selecting a split frequency point according to the fundamental frequency f0 of the large flexible attachment for which the disturbance force estimation is to be performed in a fixed boundary state, and dividing the full frequency range of the large flexible attachment for which the disturbance force estimation is to be performed into a low frequency band and a high frequency band; The disturbance force of the drive motor is measured when it is no-load, and F Along (f); where F Along (f) represents the vector composed of the frequency domain response data of the disturbance force and torque of the drive motor when it is no-load, and f represents the frequency; Establish finite element models of the drive motor in two states: no-load and with large flexible attachments, and determine the internal virtual disturbance force nodes and disturbance force output nodes in the two states; Carry out transfer characteristic simulation to obtain FRF Along (f) and FRF Load (f); where FRF Along (f) represents the matrix composed of the force and torque transfer function from the internal virtual disturbance force node to the disturbance force output node when the drive motor is unloaded, FRF Load (f) represents the matrix composed of the force and torque transfer function from the internal virtual disturbance force node to the disturbance force output node when a large flexible attachment is attached; Based on the divided low frequency band and high frequency band, combined with F Along (f), FRF Along (f) and FRF Load (f) The disturbance force of the large flexible attachment is estimated and the disturbance force estimation results are obtained.

2. The method for estimating the disturbance force of a large flexible attachment based on ground test data according to claim 1 is characterized in that: If f≤f A , it is divided into the low frequency band; if f>f A , it is divided into high frequency band; among them, f A Indicates the frequency of the split frequency point.

3. The method for estimating the disturbance force of a large flexible attachment based on ground test data according to claim 2 is characterized in that: f A >2f0.

4. The method for estimating the disturbance force of a large flexible attachment based on ground test data according to claim 1 is characterized in that: The disturbance force of the drive motor is measured when it is no-load, and F Along (f) including: A six-component force measurement platform was used to measure the time-domain response data of the three-dimensional disturbance force and torque of the drive motor used to drive a large flexible accessory in the no-load state. The measured time domain response data of the three-direction disturbance force and torque of the driving motor driving the large flexible attachment in the no-load state are converted into frequency domain to obtain the frequency domain response data of the disturbance force and torque of the driving motor when it is no-load, and then the F Along (f).

5. The method for estimating the disturbance force of a large flexible attachment based on ground test data according to claim 4 is characterized in that: The sampling frequency of the time domain response data of the disturbance force and torque is greater than twice the upper limit of the disturbance force estimation frequency range.

6. The method for estimating the disturbance force of a large flexible attachment based on ground test data according to claim 1 is characterized in that: Finite element models of the drive motor in two states, no-load and with large flexible attachments, are established respectively. The internal virtual disturbance force nodes and disturbance force output nodes of the drive motor in two states, no-load and with large flexible attachments, are determined, including: Establish a first finite element model of the drive motor in the no-load state; use a multi-point constraint unit (MPC) in the first finite element model to connect the edge nodes of the rotation axis of the drive motor in the first finite element model with the center of the rotation axis as internal virtual disturbance force nodes of the drive motor in the no-load state; connect the interface nodes of the drive motor and the spacecraft in the first finite element model as disturbance force output nodes of the drive motor in the no-load state; A second finite element model with a large flexible attachment state was established. A multi-point constraint unit (MPC) was used in the second finite element model to connect the edge node of the rotation axis of the driving motor in the second finite element model with the center of the rotation axis as the internal virtual disturbance force node in the state with a large flexible attachment. The driving motor in the second finite element model was connected to the spacecraft connection interface node as the disturbance force output node in the state with a large flexible attachment.

7. The method for estimating the disturbance force of a large flexible attachment based on ground test data according to claim 6 is characterized in that: The driving motor part in the first finite element model is completely consistent with the driving motor part in the second finite element model; the internal virtual disturbance force node in the first finite element model is completely consistent with the internal virtual disturbance force node in the second finite element model; The disturbance force output node in the first finite element model is completely consistent with the disturbance force output node in the second finite element model.

8. The method for estimating the disturbance force of a large flexible attachment based on ground test data according to claim 6 is characterized in that: Carry out transfer characteristic simulation to obtain FRF Along (f) and FRF Load (f) including: The frequency response analysis of the low frequency band is performed in the first finite element model. The unit disturbance force and torque in three directions are applied to the internal virtual disturbance force node of the drive motor in the no-load state in sequence. The force and torque transfer function from the internal virtual disturbance force node of the drive motor in the no-load state to the disturbance force output node of the drive motor in the no-load state is obtained, and then the FRF is obtained. Along (f); The frequency response analysis of the low frequency band is performed in the second finite element model. The unit disturbance force and moment in three directions are applied to the internal virtual disturbance force node in the state with large flexible attachments in sequence. The force and moment transfer function from the internal virtual disturbance force node in the state with large flexible attachments to the disturbance force output node in the state with large flexible attachments is obtained, and then the FRF is obtained. Load (f).

9. The method for estimating the disturbance force of a large flexible attachment based on ground test data according to claim 1, characterized in that: Based on the divided low frequency band and high frequency band, combined with F Along (f), FRF Along (f) and FRF Load (f) Estimate the disturbance force of the large flexible attachment and obtain the disturbance force estimation results, including: When f≤f A When: [F Load (f)]=[FRF Load (f)]·[FRF Along (f)] -1 ·[F Along (f)] When f>f A When: [F Load (f)]≈[F Along (f)] Among them, [F Load (f)] represents the disturbance force estimation results.

10. The method for estimating the disturbance force of a large flexible attachment based on ground test data according to claim 1, characterized in that: The rotation rate of the drive motor when it is unloaded is consistent with the common rotation rate of the drive motor when it is driving a large flexible attachment on track.

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