A flexible and agile spacecraft attitude control method under asymmetric time-varying constraints

Abstract

The present invention relates to a method for attitude control of a flexible agile spacecraft under asymmetric time-varying constraints, including: establishing an attitude control model of a flexible agile spacecraft with respect to flexible vibration, unknown external disturbance torque and uncertainty of inertial parameters; establishing a full-state constraint inequality of the agile spacecraft; designing a modal observer and a disturbance observer of the agile spacecraft, constructing an attitude controller of a flexible agile spacecraft under asymmetric full-state constraints, and controlling the attitude of the agile spacecraft using the flexible agile spacecraft attitude controller. The method realizes the asymmetric full-state constraint control performance of the flexible agile spacecraft because the priority of the state constraints is directly processed without error transformation. In addition, in the presence of multiple constraints and disturbances, the attitude control performance and system robustness can be improved.

Description

Technical Field

[0001] The invention relates to the field of spacecraft control technology, and in particular to a flexible and agile spacecraft attitude control method under asymmetric time-varying constraints. Background Art

[0002] As the core of the space race, spacecraft is the carrier of human exploration of space. However, with the increasing maturity of rocket launch technology and satellite control technology, launching spacecraft is no longer the exclusive right of aerospace powers, and the number of satellites in orbit has also increased exponentially. As an important carrier for earth observation, remote sensing satellites are very important for climate observation, disaster forecasting, terrain detection, traffic monitoring, etc. The number of remote sensing satellites in a country can certainly be used as a factor in judging the strength of its aerospace capabilities, but in addition to the number, the performance of a single spacecraft can better reflect the level of scientific and technological development. From low resolution to high resolution, from earth observation to deep space exploration, from non-agile to agile maneuvers, remote sensing satellites are developing in the direction of being lighter, more agile, and more intelligent. Enhancing the autonomous decision-making and control capabilities of remote sensing spacecraft, improving the efficiency of satellite in-orbit operation, and extending the service life of satellites are the foundation for my country's aerospace technology to stand on the world stage.

[0003] Most of the early remote sensing missions used non-agile spacecraft, which did not have the ability to maneuver in attitude and could only achieve attitude stabilization. Later, the emergence of semi-agile spacecraft increased the flexibility of observation to a certain extent. They have the ability to maneuver in the rolling direction, but still do not have the ability to maneuver quickly in the pitch axis direction. Semi-agile spacecraft can basically meet the needs of earth observation, but the observation efficiency is limited by the maneuverability and lacks the ability to continuously track the target. Agile satellites have the ability to maneuver quickly in three axes, such as the French Pleiades series, the American WorldView series, and the QuickBird satellite, which greatly improves the efficiency of satellite observation and is a major breakthrough in the development of aerospace technology. For remote sensing satellites, the improvement of attitude maneuverability means that more observation tasks can be completed within a limited time window.

[0004] In recent years, agile spacecraft has attracted extensive attention from researchers at home and abroad for its three-axis rapid maneuverability and high pointing accuracy. It can not only meet the needs of multi-target observation and rapid switching target detection in space science, but also provide on-orbit maneuvering target detection and monitoring services for space monitoring. In addition, agile spacecraft can also achieve multi-target imaging, expand the observation range, and improve the observation efficiency of remote sensing observation. This makes agile spacecraft widely used in many fields, but also puts forward more stringent requirements for the attitude control system of agile spacecraft.

[0005] The attitude control system is one of the most complex systems in a spacecraft system and is also the key to successfully executing a spacecraft's space mission. There are various limitations on the attitude control system, such as the light-shielding requirements of onboard optical instruments, the pointing requirements of payloads, angular velocity measurement and maneuvering restrictions, and the control capabilities of actuators. For agile spacecraft, the attitude of agile spacecraft is time-varying due to the dynamic observation of targets and the frequent switching of multiple targets. Therefore, how to solve the attitude control problem of agile spacecraft when facing asymmetric time-varying full-state constraints is a challenge that must be faced. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a flexible agile spacecraft attitude control method under asymmetric time-varying constraints, which can not only effectively deal with flexible vibration, inertial uncertainty and external interference, but also has attitude constraint performance, priority of directly processing state constraints without error transformation, and strong robustness.

[0007] To solve the above problems, the present invention provides a flexible and agile spacecraft attitude control method under asymmetric time-varying constraints, the method comprising the following steps:

[0008] S1. According to the state and dynamic characteristics of the agile spacecraft during on-orbit operation, an attitude control model of the flexible agile spacecraft is established with respect to the flexible vibration, unknown external disturbance torque and uncertainty of inertial parameters;

[0009] S2. Establishing a full-state constraint inequality for the agile spacecraft, wherein the full-state constraint inequality includes an asymmetric time-varying attitude constraint and an angular velocity constraint;

[0010] S3. According to the attitude control model established in step S1, a modal observer and a disturbance observer of the agile spacecraft are designed; the modal observer is used to obtain online observation values ​​of flexible vibration, and the disturbance observer is used to obtain online observation values ​​of composite disturbance composed of unknown external disturbance torque and inertia parameter uncertainty;

[0011] S4, constructing an asymmetric time-varying integral Lyapunov function for processing attitude constraints according to the full-state constraint inequality established in step S2, and constructing a constant integral Lyapunov function for processing angular velocity constraints according to the full-state constraint inequality established in step S2;

[0012] S5. According to the attitude control model established in step S1, the full-state constraint inequality established in step S2, the online observation value obtained in step S3, and the asymmetric time-varying integral Lyapunov function and the constant integral Lyapunov function established in step S4, a flexible agile spacecraft attitude controller based on asymmetric full-state constraints is constructed, and the attitude of the agile spacecraft is controlled by using the flexible agile spacecraft attitude controller.

[0013] Preferably, in step S1, the expression of the posture control model is:

[0014] ;

[0015] in, , , , , represents the orbital angular velocity, represents the semi-major axis of the orbit, , represents the gravitational parameter, , represents the attitude angle vector, , as well as They represent the roll angle, pitch angle, and yaw angle of the flexible and agile spacecraft respectively; , represents the angular velocity vector of the flexible agile spacecraft system relative to the inertial system; , express dimensional modal coordinate vector, , represents the defined total modal velocity, , Represents the coupling coefficient matrix between the vibration of the flexible structure and the rotation of the rigid body; , , , represents the damping ratio of the flexible structure; , represents the nominal part of the moment of inertia of the rigid body of the flexible agile spacecraft, , represents the moment of inertia matrix of the rigid body of the flexible agile spacecraft, , represents the total attitude inertia matrix of the flexible agile spacecraft, , represents the bounded unknown inertia matrix; , Represents the interference composed of modal vibration related terms, unknown external interference torque and unknown inertia, , represents the modal vibration related terms, , represents composite interference, , represents the unknown external disturbance torque vector acting on the flexible agile spacecraft; , represents the control torque vector with saturation constraint, ; represents the maximum control torque provided by the actuator, and , represents the control torque vector of the attitude controller of the flexible agile spacecraft, , Indicates the saturation of the control torque; the matrix , Respectively expressed as: , , represents the n-dimensional identity matrix, .

[0016] Preferably, in step S2, the full-state constraint inequality is expressed as:

[0017] ;

[0018] in, and They represent the upper and lower bounds of the asymmetric time-varying attitude angle, which are the asymmetric time-varying attitude constraints; Represents the angular velocity boundary, that is, the angular velocity constraint.

[0019] Preferably, in step S3, the structures of the modal observer and the disturbance observer of the agile spacecraft are expressed as follows:

[0020] ;

[0021] ;

[0022] in, and They represent the flexible vibration modes respectively. and The online observation value of Represents the composite disturbance consisting of unknown external disturbance torque and inertia parameter uncertainty The online observation value of , represents the gain matrix of the modal observer, represents the auxiliary variable of the disturbance observer, , represents the gain matrix of the disturbance observer, , , , , represents the asymmetric virtual control vector, , Represents auxiliary variables; , Indicates the angular velocity constraint in the X-axis direction, Indicates the angular velocity constraint in the Y-axis direction, Represents the angular velocity constraint in the Z-axis direction.

[0023] Preferably, in step S4, the asymmetric time-varying integral Lyapunov function for processing attitude angle constraints is specifically expressed as:

[0024] ;

[0025] in, Expressing expectation, , represents the attitude angle error, , represents the integration variable.

[0026] Preferably, in step S4, the constant integral type Lyapunov function for processing angular velocity constraints is specifically expressed as:

[0027] ;

[0028] in, represents the angular velocity error, , represents the asymmetric stable control signal, represents the integration variable.

[0029] Preferably, in step S5, the flexible agile spacecraft attitude controller under the asymmetric full-state constraint is specifically expressed as:

[0030] ;

[0031] in, represents the online observation value of the modal vibration related terms, represents the positive design constant, , represents auxiliary variables, , represents the asymmetric virtual control vector, , represents the design parameter matrix, , , , , represents the identity matrix; , , , ,

[0032] , represents the upper bound of the asymmetric time-varying roll angle at time t, represents the upper bound of the asymmetric time-varying pitch angle at time t, represents the upper bound of the asymmetric time-varying yaw angle at time t.

[0033] The beneficial effects of the present invention are as follows: the present invention provides a method for attitude control of a flexible agile spacecraft under asymmetric time-varying constraints. Since the method directly processes the priority of state constraints without error transformation, the proposed asymmetric TVIBLF and constant IBLF are directly used for time-varying attitude constraint problems and angular velocity constraint problems, achieving asymmetric full-state constraint control performance of flexible agile spacecraft. In addition, the method also takes into account flexible vibration, inertial uncertainty and unknown external interference torque, designs a modal observer to deal with flexible vibration, and uses a multivariable nonlinear disturbance observer to eliminate disturbance effects including inertial uncertainty. Therefore, in the presence of multiple constraints and disturbances, the attitude control performance and system robustness are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of a method for attitude control of a flexible and agile spacecraft under asymmetric time-varying constraints of the present invention;

[0035] Figure 2 It is a schematic diagram of the posture tracking curve under the asymmetric time-varying posture constraint in the present invention;

[0036] Figure 3 It is a schematic diagram of an angular velocity tracking curve under a constant constraint in the present invention;

[0037] Figure 4 It is a schematic diagram of the interference observation error curve in the present invention;

[0038] Figure 5 is a schematic diagram of a modal observation error curve in the present invention;

[0039] Figure 6 It is a schematic diagram of the custom modal observation error curve in the present invention. DETAILED DESCRIPTION

[0040] The present invention relates to a flexible and agile spacecraft attitude control method under asymmetric time-varying constraints, such as Figure 1 As shown, the method comprises the following steps:

[0041] Step 1: According to the real-time state and dynamic characteristics of the agile spacecraft during on-orbit operation, an attitude control model of the flexible agile spacecraft is established with respect to flexible vibration, unknown external interference torque and uncertainty of inertial parameters;

[0042] Furthermore, the specific implementation process of step one is:

[0043] First, the attitude kinematics and dynamics equations of an agile spacecraft with flexible appendages during on-orbit operation are established:

[0044] ;

[0045] In the formula, , represents the orbital angular velocity, represents the semi-major axis of the orbit. In the specific implementation process, , , represents the gravitational parameter, , represents the attitude angle vector, , as well as They represent the roll angle, pitch angle, and yaw angle of the agile spacecraft respectively; , Represents the angular velocity vector of the spacecraft system relative to the inertial system; in the specific implementation process, take the initial value , .

[0046] In the formula, , express dimensional modal coordinate vector, , represents the defined total modal velocity, , Represents the coupling coefficient matrix between the vibration of the flexible structure and the rotation of the rigid body; , , , , represents the damping ratio of the flexible structure; and Represent the damping ratio and modal frequency of the flexible structure respectively; then the initial modal variables, damping ratio, modal frequency matrix and coupling coefficient matrix of the first four modes are:

[0047] ;

[0048] The coupling coefficient matrix between the vibration of the flexible structure and the rotation of the rigid body is obtained as follows:

[0049] ;

[0050] In the formula, , represents the moment of inertia matrix of the rigid body of the flexible spacecraft, , represents the total attitude inertia matrix of the flexible spacecraft, represents the control torque vector; , represents the modal vibration related terms, , represents the unknown external disturbance torque vector acting on the agile spacecraft; , represents the control torque vector with saturation constraint, ; represents the maximum control torque provided by the actuator, and , represents the control torque vector, , Indicates the saturation of the control torque; the matrix , Respectively expressed as: , , represents the n-dimensional unit matrix. In the specific implementation process, take .

[0051] During the on-orbit maneuvers of agile spacecraft, the load motion, working fluid and fuel consumption will lead to uncertainty in the inertia parameters. is a symmetric positive definite matrix, take , represents the bounded unknown inertia matrix, It represents the nominal part of the moment of inertia of the rigid body of the flexible spacecraft. In the specific implementation process, its value is taken as:

[0052] ;

[0053] The attitude control model of the flexible agile spacecraft with respect to flexible vibration, unknown external disturbance torque and uncertainty of inertial parameters is obtained as follows:

[0054] ;

[0055] in, , , Represents the interference composed of modal vibration related terms, unknown external interference torque and unknown inertia, the matrix , Respectively expressed as: , .

[0056] Step 2: Establishing the full-state constraint inequality of the agile spacecraft, wherein the full-state constraint inequality includes an asymmetric time-varying attitude constraint and an angular velocity constraint;

[0057] Furthermore, the specific implementation process of step 2 is:

[0058] An asymmetric time-varying attitude constraint and an angular velocity constraint of an agile spacecraft are established to keep the attitude and angular velocity of the agile spacecraft within a set value; the asymmetric time-varying attitude constraint and the angular velocity constraint of the agile spacecraft are expressed as:

[0059] ;

[0060] in, and They represent the upper and lower bounds of the asymmetric time-varying attitude angle, which are the asymmetric time-varying attitude constraints; Represents the angular velocity boundary, which is the angular velocity constraint;

[0061] In the specific implementation process, the angular velocity boundary is taken as: , the asymmetric time-varying attitude constraint boundary function satisfies:

[0062] .

[0063] Step 3: According to the attitude control model established in step 1, a modal observer and a disturbance observer of the agile spacecraft are designed; the modal observer is used to obtain online observation values ​​of the flexible vibration mode, and the disturbance observer is used to obtain online observation values ​​of the composite disturbance composed of unknown external disturbance torque and inertia parameter uncertainty;

[0064] Furthermore, the specific implementation process of step three is:

[0065] In order to solve the influence of flexible vibration, inertial uncertainty and unknown external disturbance torque on flexible agile spacecraft, the modal observer and multivariable nonlinear disturbance observer of agile spacecraft are designed to eliminate these influences.

[0066] The structures of the modal observer and disturbance observer are expressed as follows:

[0067] ;

[0068] ;

[0069] in, and They represent the flexible vibration modes respectively. and The online observation value of Represents the composite disturbance consisting of unknown external disturbance torque and inertia parameter uncertainty The online observation value of , Represents the gain matrix of the modal observer. In the specific implementation process, take , represents the auxiliary variable of the disturbance observer, and takes , , , ;

[0070] In order to compensate for the nonlinearity of the control torque caused by actuator saturation, a second-order auxiliary system is introduced:

[0071] ;

[0072] in, , Indicates the positive design constant. In the specific implementation process, , , and is an auxiliary variable.

[0073] Step 4: construct an asymmetric time-varying integral Lyapunov function (TVIBLF) for processing attitude angle constraints according to the full-state constraint inequality established in step S2, and construct a constant integral Lyapunov function (IBLF) for processing angular velocity constraints according to the full-state constraint inequality established in step 2;

[0074] Furthermore, the specific implementation process of step 4 is as follows:

[0075] In order to ensure the posture under asymmetric constraints, an asymmetric time-varying integral Lyapunov function (TVIBLF) of the following form is designed:

[0076] ;

[0077] in, Expressing expectation, , represents the attitude angle error, , Represents the integral variable; the attitude angle error vector is defined as:

[0078] ;

[0079] The derivative of is: ;

[0080] in, In the specific implementation process, according to the mission requirements, it is assumed that the flexible agile satellite needs to maneuver three times in a short period of time. The expected attitudes of the three maneuvers are , and ;

[0081] Introduce the following first-order filter:

[0082] ;

[0083] in, , , the filter error is , represents the asymmetric virtual control vector, It is an asymmetric stable control signal.

[0084] In general, the angular velocity of agile spacecraft is also restricted within finite boundaries due to measurement and performance requirements. Therefore, the construction of the constant integral type Lyapunov function (IBLF) for handling angular velocity constraints is:

[0085] ;

[0086] in, represents the angular velocity error, , represents the asymmetric stable control signal, is a continuously differentiable function, represents the integral variable; and there exists a positive constant , ,satisfy ; Define angular velocity error:

[0087] ;in, ; The derivative of is:

[0088] ;

[0089] Step 5. Based on the attitude control model established in step 1, the full-state constraint inequality established in step 2, the online observation values ​​obtained in step 3, and the asymmetric TVIBLF and constant IBLF established in step 4, a flexible agile spacecraft attitude controller under asymmetric full-state constraints is constructed, and the attitude of the agile spacecraft is controlled using the flexible agile spacecraft attitude controller.

[0090] Furthermore, the specific process of step five is:

[0091] definition: ;

[0092] in, exist is continuously differentiable;

[0093] The asymmetric stable control signal Designed for:

[0094] ;

[0095] in,

[0096] ;

[0097] ;

[0098] ;

[0099] ;

[0100] ;

[0101] In the specific implementation process, ;

[0102] Then we get The derivative of is:

[0103] ;

[0104] The derivative of is:

[0105] ;

[0106] in,

[0107] ;

[0108] ;

[0109] Finally, the attitude controller of flexible agile spacecraft under asymmetric full-state constraints based on disturbance observer is obtained as follows:

[0110] ;

[0111] in, represents the design parameter matrix, , , ; In the specific implementation process, take the parameter matrix .

[0112] In order to verify the superiority of the flexible agile spacecraft attitude control method under asymmetric time-varying constraints proposed in the present invention, simulation verification is carried out using Simulink based on the parameters taken in the above specific implementation process.

[0113] Through numerical simulation verification, it can be obtained Figure 2~Figure 6 ,in, Figure 2 and Figure 3 They are respectively the attitude tracking curve under asymmetric time-varying constraints and the angular velocity attitude tracking curve under constant constraints. Figure 2 and Figure 3 It can be found from observation that the attitude control of a flexible agile spacecraft under an asymmetric time-varying constraint of the present invention is performed, which not only ensures the attitude tracking performance, but also realizes the full-state attitude constraint control of the flexible agile spacecraft. Figure 4 is the error diagram of the disturbance observer, where It can be seen that the disturbance observer makes a high-precision estimate of the disturbance composed of inertial uncertainty and unknown external disturbance torque, and the disturbance estimation error gradually decreases and converges to the range of 0.05Nm. Figure 5 and Figure 6 shows the error curves of the modal variables, Figure 5 middle, ,exist Figure 6 middle, , and They are the modal errors of the first four orders and the corresponding custom modal errors. It is not difficult to see that the designed modal observer has good observation performance and the modal estimation error gradually decreases. and Finally, they are and .

[0114] The above simulation results show that the present invention can realize agile spacecraft attitude control under full-state constraints when the system has flexible vibration, inertia uncertainty and external interference.

[0115] The above description is only a specific implementation case of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A flexible and agile spacecraft attitude control method under asymmetric time-varying constraints, characterized by: The method comprises the following steps: S1. According to the real-time state and dynamic characteristics of the agile spacecraft during on-orbit operation, an attitude control model of the flexible agile spacecraft is established with respect to the flexible vibration, unknown external disturbance torque and uncertainty of inertial parameters; S2. Establishing a full-state constraint inequality for the agile spacecraft, wherein the full-state constraint inequality includes an asymmetric time-varying attitude constraint and an angular velocity constraint; S3. According to the attitude control model established in step S1, a modal observer and a disturbance observer of the agile spacecraft are constructed; the modal observer is used to obtain online observation values ​​of flexible vibration, and the disturbance observer is used to obtain online observation values ​​of composite disturbance composed of unknown external disturbance torque and inertia parameter uncertainty; S4, constructing an asymmetric time-varying integral Lyapunov function for processing attitude constraints according to the full-state constraint inequality established in step S2, and constructing a constant integral Lyapunov function for processing angular velocity constraints according to the full-state constraint inequality established in step S2; S5. According to the attitude control model established in step S1, the full-state constraint inequality established in step S2, the online observation value obtained in step S3, and the asymmetric time-varying integral Lyapunov function and the constant integral Lyapunov function established in step S4, a flexible agile spacecraft attitude controller under asymmetric full-state constraints is constructed, and the attitude of the agile spacecraft is controlled by the flexible agile spacecraft attitude controller; In step S5, the flexible agile spacecraft attitude controller under the asymmetric full-state constraint is specifically expressed as: in, represents the online observation value of the modal vibration related items, c2 represents the positive design constant, represents an asymmetric virtual control vector; J m0 =J m -ΔJ,J m0 represents the nominal part of the moment of inertia of the rigid body of the flexible spacecraft, J m =JF s F s T , J m represents the moment of inertia matrix of the rigid body of the flexible spacecraft, J∈R 3×3 , J represents the total attitude inertia matrix of the flexible spacecraft, ΔJ=0.1J m0 , ΔJ represents the bounded unknown inertia matrix; F s ∈R 3×n , F s Represents the coupling coefficient matrix between the vibration of the flexible structure and the rotation of the rigid body; ω=[ω x ω y ω z ] T , ω represents the angular velocity vector of the spacecraft system relative to the inertial system; C=2ζΩ,ζ∈R n×n ,Ω∈R n×n , C represents the damping ratio of the flexible structure; represents the online observation value of the composite disturbance d2 composed of unknown external disturbance torque and inertia parameter uncertainty, k ω represents the design parameter matrix, I∈R 3 ×3 , I represents the identity matrix; θ and ψ represent the roll angle, pitch angle, and yaw angle of the agile spacecraft, respectively; k cai (t) and k cbi (t) represent the upper and lower bounds of the asymmetric time-varying attitude angle, i.e., the asymmetric time-varying attitude constraint. Represents the angular velocity boundary, that is, the angular velocity constraint, j = x, y, z.

2. The method for controlling the attitude of a flexible and agile spacecraft under an asymmetric time-varying constraint according to claim 1, characterized in that: In step S1, the expression of the posture control model is: in, ω0 represents the orbital angular velocity, a represents the orbital semi-major axis, μ = 3.986012 × 10 5 km 3 / s 2 , μ represents the gravitational parameter, Φ represents the attitude angle vector, θ and ψ represent the roll, pitch and yaw angles of the agile spacecraft respectively; ω = [ωxωyωz] T , ω represents the angular velocity vector of the spacecraft system relative to the inertial system; η∈R n , η represents the n-dimensional modal coordinate vector, Ψ represents the total modal velocity defined, F s ∈R 3×n , F s Represents the coupling coefficient matrix between the vibration of the flexible structure and the rotation of the rigid body; C = 2ζΩ, K = Ω 2 ,ζ∈R n×n ,Ω∈R n×n , C represents the damping ratio of the flexible structure; J m0 =J m -ΔJ,J m0 represents the nominal part of the moment of inertia of the rigid body of the flexible spacecraft, J m =JF s F s T , J m represents the moment of inertia matrix of the rigid body of the flexible spacecraft, J∈R 3×3 , J represents the total attitude inertia matrix of the flexible spacecraft, ΔJ=0.1J m0 , ΔJ represents the bounded unknown inertia matrix; d3 = d1 + d2, d3 represents the interference composed of modal vibration related terms, unknown external interference torque and unknown inertia, d1 = F s CΨ+F s Kη-s(ω)F s Ψ,d1 represents the modal vibration related terms, d2 represents composite interference, d represents the unknown external disturbance torque vector acting on the agile spacecraft; sat u = [sat u x sat u y sat u z ] T , sat u represents the control moment vector with saturation constraint, u max represents the maximum control torque provided by the actuator, sat u=u+Δu, u represents the control torque vector, Δu=[Δu x Δu y Δu z ] T ,Δu represents the saturation of the control torque; matrices A and B are expressed as: I n Represents the n-dimensional identity matrix.

3. The method for controlling the attitude of a flexible and agile spacecraft under an asymmetric time-varying constraint according to claim 2, characterized in that: In step S2, the full-state constraint inequality is expressed as: Among them, k cai (t) and k cbi (t) respectively represent the upper and lower bounds of the asymmetric time-varying attitude angle, i.e., the asymmetric time-varying attitude constraint; Represents the angular velocity boundary, that is, the angular velocity constraint.

4. The method for controlling attitude of a flexible and agile spacecraft under asymmetric time-varying constraints according to claim 3 is characterized in that: In step S3, the structures of the modal observer and the disturbance observer of the agile spacecraft are expressed as follows: in, and denote the online observed values ​​of the flexible vibration modes η and Ψ, respectively. represents the online observation value of the composite disturbance d2 composed of unknown external disturbance torque and inertia parameter uncertainty, P∈R 2n×2n , P represents the gain matrix of the modal observer, z represents the auxiliary variable of the disturbance observer, D = diag[d x ,d y ,d z ]>0, D represents the gain matrix of the disturbance observer, p(ω)=DJ m0 ω, 5. The method for controlling the attitude of a flexible and agile spacecraft under an asymmetric time-varying constraint according to claim 4, characterized in that: In step S4, the asymmetric time-varying integral Lyapunov function for processing attitude angle constraints is specifically expressed as: Among them, i d Expressing expectation, z i Represents the attitude angle error, z i =ii d , δ i represents the integration variable.

6. The method for controlling attitude of a flexible and agile spacecraft under asymmetric time-varying constraints according to claim 5, characterized in that: In step S4, the constant integral type Lyapunov function for processing angular velocity constraints is specifically expressed as: in, represents the angular velocity error, represents the asymmetric stable control signal, represents the integration variable.

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