Large scale flexible spacecraft rotary inertia Kalman filtering discrimination method
Technical field
The present invention relates to a kind of spacecraft method for identification of rotational inertia, in particular to a kind of large scale flexible spacecraft rotation
Inertia Kalman filtering discrimination method.
Background technique
Document " the in-orbit identification method of Xu Wenfu, He Yong, Wang Xueqian, Liang Bin, Liu Yu spacecraft mass characterisitic parameter
[J] aerospace journal, 2010,31 (8): 1906-1914 " disclose it is a kind of on the basis of Rigid Body Dynamics Model based on the non-of PSO
The Global Optimal Problem that parameter identification problem is converted to nonlinear system is picked out spacecraft by linear optimization method, this method
Rotary inertia parameter.In the case that document the method is suitable for satellite as rigid body, does not account for large scale flexible spacecraft and scratch
Property influence of the coupling to rotary inertia parameter identification;For large scale flexible spacecraft, the rigid-flexible coefficient of coup is larger, is turning
If ignored when dynamic inertia identification, identifier substantial deviation true value will cause, so that identification be caused to fail.Therefore, this method
It is not applied for the identification of rotational inertia of large scale flexible spacecraft.
Summary of the invention
In order to overcome the shortcomings of existing spacecraft method for identification of rotational inertia, the practicability is poor, and the present invention provides a kind of large scale
Flexible spacecraft rotary inertia Kalman filtering discrimination method.This method is first against large scale flexible spacecraft, according to small angle
Spend it is motor-driven under kinetics equation determine observational equation.Then using the PD control device of closed-loop control excitation, control satellite is turned over
The angle of setting.According to observational equation, identification of rotational inertia is carried out using Kalman filtering.Due to using Kalman filtering side
Method considers that the influence factor of large scale flexible spacecraft flexibility coupling carries out identification of rotational inertia, it is in-orbit to realize rotary inertia
Identification.It reduces since the rigid-flexible coefficient of coup of spacecraft is big, flexible vibration generates attitude angle and attitude angular velocity to system
Larger impact.The rotary inertia of identification is that subsequent gesture stability provides the foundation, and enhances spacecraft attitude control system
Precision, practicability are good.
A kind of the technical solution adopted by the present invention to solve the technical problems: large scale flexible spacecraft rotary inertia karr
Graceful filter identification method, its main feature is that the following steps are included:
Step 1: determining identified parameters and inputting out the observational equation between measurement data.
Rotary inertia parameter to be identified is expressed as to the inverse form of parameter to be identified,
In formula, x is the vector for needing to estimate, each element corresponds to six elements of the inverse matrix of inertial matrix I.
For large scale flexible spacecraft, the kinetics equation under low-angle is motor-driven is
Wherein, I is satellite rotary inertia, parameter to be identified;It is spacecraft angular acceleration, ProtIt is that flexible appendage is opposite
In the rotation Coupled Rigid-flexible coefficient of body coordinate system, CηAnd KηFor the modal damping matrix and stiffness matrix of attachment, η is flexible attached
Mode of oscillation of the part under modal coordinate, T are the bonding force squares that satellite is subject to.
It obtains
It enables
It obtains
Determine that observational equation is as follows:
Z=Hx (5)
Here
Here S1、S2、S3It is rolling, pitching, yaw excitation T1、T2、T3And influence of the flexible part to spacecraft, lead to
It crossesIt shows.
Step 2: determining incentive program.
PD control device is motivated using closed-loop control, desired gesture stability torque size are as follows:
In formula, ω and Θ are respectively incremental vector needed for angular speed and Euler angle, and J is rotary inertia, and T is control force
Square, KωAnd KωFor PD control device coefficient.
Step 3: Kalman filtering recognizes.
System state equation
X (k+1)=x (k)+w (k) (8)
Observational equation
Z (k)=H (k) x (k)+v (k) (9)
In formula, w (k) and v (k) is the white noise sequence that mean value is zero, noise characteristic
E [w (k)]=E [v (k)]=0
E[w(k)wT(j)]=Qkδkj
E[v(k)vT(j)]=Rkδkj
E[w(k)vT(j)]=0
In formula, δkjFor Crow Buddhist nun gram δ function, characteristic is
QkFor nonnegative definite matrix, RkFor positive definite matrix.
The step of recognizing rotary inertia based on Kalman filtering is as follows:
The first step, prediction:
(b) P (k+1/k)=P (k/k) (11)
Second step, amendment:
(c) K (k+1)=P (k+1/k) HT(k+1)[H(k+1)P(k+1/k)HT(k+1)+Rk+1]-1 (13)
Wherein, P is error covariance matrix, and K is determining optimum gain matrix, completes large scale flexible spacecraft rotary inertia
Identification.
The beneficial effects of the present invention are: this method is first against large scale flexible spacecraft, according to low-angle it is motor-driven under
Kinetics equation determines observational equation.Then using the PD control device of closed-loop control excitation, control satellite turns over the angle of setting.
According to observational equation, identification of rotational inertia is carried out using Kalman filtering.Due to using kalman filter method, large scale is considered
The influence factor of flexible spacecraft flexibility coupling carries out identification of rotational inertia, realizes rotary inertia in-orbit identification.Reduce by
The larger impact that big, flexible vibration generates attitude angle and attitude angular velocity to system in the rigid-flexible coefficient of coup of spacecraft.Identification
Rotary inertia be subsequent gesture stability provide the foundation, enhance the precision of spacecraft attitude control system, practicability is good.
It elaborates with reference to the accompanying drawings and detailed description to the present invention.
Detailed description of the invention
Fig. 1 is the excitation curve of embodiment of the present invention method.
Fig. 2 is embodiment of the present invention method x-axis identification of rotational inertia curve graph.
Fig. 3 is embodiment of the present invention method y-axis identification of rotational inertia curve graph.
Fig. 4 is embodiment of the present invention method z-axis identification of rotational inertia curve graph.
Fig. 5 is embodiment of the present invention method xy axis product of inertia change curve.
Fig. 6 is embodiment of the present invention method xz axis product of inertia change curve.
Fig. 7 is embodiment of the present invention method yz axis product of inertia change curve.
Specific embodiment
Referring to Fig.1-7.Large scale flexible spacecraft rotary inertia Kalman filtering discrimination method specific steps of the present invention are such as
Under:
Step 1: determining identified parameters and inputs out the observational equation between measurement data.
Rotary inertia parameter to be identified is expressed as to the inverse form of parameter to be identified,
X is the vector for needing to estimate, each element corresponds to six elements of the inverse matrix of inertial matrix I.For example,It is right
Answer the I of the inverse matrix of inertial matrixxxCorresponding element.
For large scale flexible spacecraft, the kinetics equation under low-angle is motor-driven is
Wherein, I is satellite rotary inertia, parameter to be identified;It is spacecraft angular acceleration, ProtIt is that flexible appendage is opposite
In the rotation Coupled Rigid-flexible coefficient of body coordinate system, CηAnd KηFor the modal damping matrix and stiffness matrix of attachment, η is flexible attached
Mode of oscillation of the part under modal coordinate, T are the bonding force squares that satellite is subject to.
It obtains
It enables
It obtains
Determine that observational equation is as follows:
Z=Hx (5)
Here
Here S1、S2、S3It is rolling, pitching, yaw excitation T1、T2、T3And influence of the flexible part to spacecraft, lead to
It crossesIt shows.
Step 2: incentive program is determined.
The incentive program that this step is designed correctly, control satellite turn over the angle of setting.It designs PD control device and uses closed loop
Control excitation, designs desired gesture stability torque size are as follows:
ω and Θ is respectively incremental vector needed for angular speed and Euler angle, and J is rotary inertia, and T is control moment, KωWith
KωFor PD control device coefficient.
Step 3: Kalman filtering identification.
System state equation
X (k+1)=x (k)+w (k) (8)
Observational equation
Z (k)=H (k) x (k)+v (k) (9)
In formula, w (k) and v (k) is the white noise sequence that mean value is zero, noise characteristic
E [w (k)]=E [v (k)]=0
E[w(k)wT(j)]=Qkδkj
E[v(k)vT(j)]=Rkδkj
E[w(k)vT(j)]=0
In formula, δkjFor Crow Buddhist nun gram (Kroneker) δ function, characteristic is
QkFor nonnegative definite matrix, RkFor positive definite matrix.
The step of recognizing rotary inertia based on Kalman filtering is as follows:
The first step, prediction:
(2) P (k+1/k)=P (k/k) (11)
Second step, amendment:
(1) K (k+1)=P (k+1/k) HT(k+1)[H(k+1)P(k+1/k)HT(k+1)+Rk+1]-1 (13)
Wherein, P is error covariance matrix, and K is determining optimum gain matrix, and above step can be completed with large-scale flexible
The identification of rotational inertia of windsurfing satellite.
Example
The selection one typical space flight with large-scale flexible windsurfing is illustrated.
In this example, the gross mass of system is 1.5803e+06kg, inertia J are as follows:
Consider ten rank mode
Prot=
The first row: 1.71909719232044e-11-1.29102143360427e-17 2.78433175158856e-
16
2.89832740153608e-12 -1.62565723128785e-17 1.16330704617975e-13
313397.818665696 -6.29499312000034e-17 7.17940509526988e-13
-38.5913142691036
Second row: 0.0206769221783322 86750.3989421326 41199.5429747264
-6.87008404112719 12912.7899794399 6.13468084264884 -
4.03978886873467e-29
-45074.3325616449 -0.113569550719451 -53.3032831613732
The third line: 280749.877191912-0.210839800425953 4.54715882740672
47333.2785184105 -0.265489973505254 1899.82458124203
-1.91900817744354e-11 -1.02805039362318 11724.8583024403
-66349.2699140260
Step 1: determining identified parameters and inputs out the observational equation between measurement data.
Step 2: incentive program determines.
The initial Euler's angular displacement of system and angular speed deviation are as follows:
Θ=[0.2,0.2 0.2] deg
ω=[0.001,0.001,0.001] deg/s
Control process is from initial deviation to zero.
Design desired gesture stability torque size are as follows:
ω and Θ is respectively incremental vector needed for angular speed and Euler angle.
Posture process is referring to Fig. 1.
Step 3: Kalman filtering identification.
Kalman filtering identification is divided into two steps, first is that prediction, second is that amendment, is turned according to Kalman filtering step
The identification of dynamic inertia.It can be seen that all axes of inertia Identification Errors referring to Fig. 2-Fig. 7 emulation deviation and be less than 10%.