Spacecraft autonomous reconstruction method based on control energy interval division

Abstract

The invention discloses a spacecraft autonomous reconstruction method based on control energy interval division, and the method comprises the steps: firstly describing a failure fault of an actuator based on residual effective factors, and obtaining a corresponding system configuration; then, a callable fault set is determined through a callable criterion, and a control energy cost function and an allowable cost upper limit are set, so that a combination of lowest residual effective factors and a reconfigurable fault set are determined; secondly, performing interval division on a control energy cost function value field and obtaining a series of reconfigurable fault subsets; thirdly, performing normal and fault mode integrated design on each reconfigurable fault subset to form an active and passive combined reconfiguration control library; and finally, designing a decision module, so that each fault subset uniquely corresponds to a certain control law in the control library. The method has the low operation complexity of a passive reconstruction method and the low control energy consumption of an active reconstruction method.

Description

Technical Field

[0001] The invention relates to a spacecraft autonomous reconstruction method based on control energy interval division, belonging to the technical field of spacecraft overall design. Background Art

[0002] Actuator failures in control systems can affect system stability and control performance, leading to safety accidents. To this end, it is necessary to develop appropriate fault-tolerant control strategies to minimize performance losses while ensuring the achievement of control objectives. Given the high reliability requirements of space missions, when actuator failures occur in spacecraft control systems, the faulty actuators are usually shut down and only normal components are used to continue the mission. This strategy is called fault-tolerant control based on system reconstruction.

[0003] System reconstruction can be divided into two modes: active and passive. Active reconstruction, such as the real-time active reconstruction fault-tolerant control method in Chinese patent CN106843254B, is to design corresponding control laws according to different faults. It is flexible and efficient, but difficult to implement and requires complex fault identification and system reconstruction, which increases the computational burden, especially for on-orbit spacecraft with limited resources. In addition, the delay and uncertainty of the fault identification process will weaken the effect of reconstruction, and may cause adverse transient responses when the controller switches, further damaging system components.

[0004] Passive reconstruction, such as the passive fault-tolerant control method of a rigid satellite attitude system based on adaptive PI control in Chinese patent CN107831774A, is based on the use of a fixed controller with a certain degree of robustness to deal with all tolerable faults, which is simple and easy to implement; passive reconstruction does not require complex fault identification or system reconstruction mechanisms, is simple to operate, and has no response delay. Therefore, it is more effective when the reaction time after a fault is short, and the system response is smoother. However, this method will come at the expense of reducing the overall system performance.

[0005] If we choose to shut down the corresponding actuator directly when the actuator failure is not serious, it will inevitably cause a waste of control capabilities and hardware resources. Therefore, it is necessary to introduce a residual effective factor to measure the severity of the actuator failure. However, the definition domain of the residual effective factor is obviously an infinite set, and it is certainly unrealistic to actively reconstruct each type of failure. Therefore, how to combine the advantages of active and passive reconstruction to provide a reconstruction strategy that takes actuator failure into consideration is a problem worthy of study. Summary of the invention

[0006] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art, to provide a spacecraft autonomous reconstruction method based on control energy interval division, to combine the advantages of active reconstruction method and passive reconstruction method, to formulate a reconstruction strategy taking actuator failure into account, and to balance the implementation effect and implementation difficulty of the reconstruction scheme.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A method for autonomous reconstruction of spacecraft based on control energy interval division, firstly, based on the residual effective factor, the failure of the actuator is described and the corresponding system configuration is obtained; then, the stabilizable fault set is determined by the stabilizable criterion, and the control energy cost function and the allowable cost upper limit are set to determine the combination of the lowest residual effective factor and the reconfigurable fault set; secondly, the control energy cost function value domain is divided into intervals and a series of reconfigurable fault subsets are obtained; thirdly, for each reconfigurable fault subset, the normal and fault mode are integrated and designed to form an active and passive combined reconstruction control library; finally, a decision module is designed so that each fault subset uniquely corresponds to a control law in the control library. The invention has both the low computational complexity of the passive reconstruction method and the low control energy consumption of the active reconstruction method.

[0009] More specifically:

[0010] (1) Based on the spacecraft system model, for the actuator failure cases of existing spacecraft, the residual effective factor μ is used to describe the actuator failure fault f(μ), so as to obtain the full set of all fault components

[0011] (2) The system configuration in the fault-free case is (A, B0), where A is the system matrix of the control system and B0 is the input matrix. According to the actuator failure f(μ) obtained in step (1), the corresponding column of B0 is multiplied by the residual effective factor μ, and then the system configuration (A, B0) corresponding to the fault f(μ) is obtained. f ), which is convenient for solving the Riccati equation later.

[0012] (3) Based on the stabilization theory, determine the subset of faults f(μ) obtained in step (1) for which the system can be stabilized: Set the control energy cost function and the permissible cost ceiling Where x0 is the initial state of the system, u is the control input, Q, R, and N are all positive matrices related to the control cost, so as to determine the boundary f(μ min ) and reconfigurable fault collection

[0013] (4) Divide the control energy cost function range evenly into n intervals:

[0014] J k ={j|j0+0.1*(k-1)*(j max -j0)<j≤j0+0.1*k*(j max-j0)},k=1,2,...,n

[0015] k is the interval number; j0 is the minimum control energy cost of the fault-free system, and the reconfigurable fault set obtained in step (3) is Divided into a series of reconfigurable fault subsets: The setting of the number of subsets n needs to consider the computational complexity. Obviously, The subscripts 1, 2, 3, ... n represent the sequence numbers of the fault subsets.

[0016] (5) For each reconfigurable fault subset in step (4) Take the largest remaining effective factor as the fault reference and repeat step (2) to obtain the input matrix B under the fault Fk , solve the system matrix A, input matrix B Fk , the Riccati equation composed of positive definite matrices Q and R:

[0017]

[0018] According to the solution matrix W of the equation Fk Set the optimal reconstruction control law respectively This forms a reconstruction control library

[0019] (6) The reconfigurable fault subset obtained in step (4) The reconstructed control library obtained in step (5) The control law in k Strictly corresponding, when the actuator residual effective factor μ decreases, the control law is switched in time.

[0020] An electronic device, comprising:

[0021] Processor; and

[0022] a memory for storing computer program instructions;

[0023] When the computer program instructions are loaded and executed by the processor, the processor executes the above-mentioned spacecraft autonomous reconstruction method.

[0024] A computer-readable storage medium stores computer program instructions, which, when loaded and executed by a processor, cause the processor to execute the above-mentioned spacecraft autonomous reconstruction method.

[0025] A computer program product stored on a non-transitory computer-readable medium, the computer program product comprising program codes for implementing the above-mentioned spacecraft autonomous reconfiguration method.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The method of the present invention analyzes the system configuration corresponding to the actuator failure fault through the residual effective factor, and further classifies the reconfigurable fault set by dividing the value range of the control energy cost function. On this basis, the reconstruction control law is set up respectively, which makes full use of the actuators that have not completely failed, and avoids the waste of spacecraft hardware resources to a certain extent.

[0028] (2) The method of the present invention fully utilizes the advantages of active reconstruction and reduces the overall reconstruction cost of the reconstruction strategy while achieving the reconstruction goal. Compared with the traditional active reconstruction method, it effectively reduces the computational complexity and is very suitable for on-orbit spacecraft with limited computing resources but high control performance requirements.

[0029] (3) The method of the present invention is an extension of the passive reconstruction concept. By establishing a reconstruction control library, each reconfigurable fault subset corresponds to only one optimal control law, thereby achieving comprehensive coverage of reconfigurable faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] A spacecraft autonomous reconstruction method based on control energy interval division, such as Figure 1 As shown, including:

[0033] (1) Based on the spacecraft system model, for the actuator failure cases of existing spacecraft, a general spacecraft uses four flywheels as actuators. Assuming that the failure degree of the four actuators is the same, the remaining effective factor satisfies μ i =μ∈[0,1], i=1,2,3,4, i is the serial number of the actuator, μ=1 means that all actuators in the system have no faults, thus obtaining the fault f(μ) and the complete set of faults

[0034] (2) According to the fault f(μ) obtained in step (1), the corresponding column of the input matrix B0 is multiplied by the residual effective factor μ, and then the system configuration (A, B) corresponding to the fault f(μ) is obtained. f ), where B f =B0*diag(μ), since the set of fault modes is infinite, the corresponding system configurations are also infinite.

[0035] (3) Based on the stabilization theory, determine the set of faults in the full set of faults obtained in step (1) that satisfy the stabilization of the system. Usually μ>0 can ensure that the system can be stabilized; for this purpose, an energy cost function related to the control input u is set and the cost cap Q, R, and N are all positive definite matrices related to the control cost, x0 is the initial state of the system; the optimal control energy cost corresponding to the fault f(μ) is The solution matrix W f The following Riccati equation is satisfied:

[0036]

[0037] W f is the solution of the Riccati equation, when j f ≤j max When , the fault f(μ) is said to be reconfigurable; solve to obtain the minimum remaining effective factor μ min , thereby determining the boundary of reconfigurable faults f(μ min ) and reconfigurable fault sets

[0038] (4) Divide the range of the control energy cost function into intervals. The division basis can be designed according to needs. It is assumed that it is divided into 10 intervals on average:

[0039] J k ={j|j0+0.1*(k-1)*(j max -j0)<j≤j0+0.1*k*(j max -j0)},k=1,2,...,10

[0040] k is the interval number; j0 is the minimum control energy cost of the fault-free system;

[0041] In this way, a series of reconfigurable fault subsets are obtained:

[0042] (5) For each fault subset in step (4) Repeat step (2) to obtain the input matrix B under fault Fk , solve the system matrix A, input matrix B Fk , the Riccati equation composed of positive definite matrices Q and R:

[0043]

[0044] According to the solution matrix W of the equation Fk Set the optimal reconstruction control law respectively Reconstruction control library

[0045] (6) Establishing a corresponding relationship requires: The failure mode subset obtained in step (4) The control library obtained in step (5) The only control law u k Correspondingly, so that the control law can be switched in time when the residual effective factor μ of the actuator decreases.

[0046] In summary, the above embodiments verify the feasibility and effectiveness of the spacecraft autonomous reconstruction method based on control energy interval division proposed in the present invention.

[0047] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

[0048] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A spacecraft autonomous reconstruction method based on control energy interval division, characterized in that: include: (1) The actuator failure fault f(μ) is described using the residual effective factor μ, thereby obtaining the complete set of all fault components: (2) The system configuration in the fault-free case is (A, B0), where A is the system matrix of the control system and B0 is the input matrix. According to the actuator failure f(μ) obtained in step (1), the corresponding column of B0 is multiplied by the residual effective factor μ, and then the system configuration (A, B0) corresponding to the fault f(μ) is obtained. f ), used in step (5) to solve the Riccati equation; (3) Based on the stabilization theory, determine the subset of faults f(μ) obtained in step (1) for which the system can be stabilized: Set the control energy cost function j f (x0,u) and the permissible cost upper limit j max , where x0 is the initial state of the system and u is the control input, so as to determine the boundary f(μ min ) and reconfigurable fault collection μ min is the minimum remaining effective factor; (4) Divide the control energy cost function value range evenly into n intervals; The reconfigurable fault set obtained in step (3) Partitioned into a set of reconfigurable fault subsets (5) For each reconfigurable fault subset in step (4) Take the largest remaining effective factor as the fault reference and solve the system matrix A and input matrix B Fk , positive definite matrices Q, R, and the solution matrix W Fk , and further set the optimal reconstruction control law This forms a reconstruction control library (6) The reconfigurable fault subset obtained in step (4) The reconstructed control library obtained in step (5) The control law in k Strictly corresponding, when the actuator residual effective factor μ decreases, the control law is switched in time.

2. The spacecraft autonomous reconstruction method according to claim 1, characterized in that: The control energy cost function is: Among them, Q, R, and N are all positive definite matrices related to the control cost.

3. The spacecraft autonomous reconstruction method according to claim 2, characterized in that: The maximum allowable cost is:

4. The spacecraft autonomous reconstruction method according to claim 1, characterized in that: The range of the control energy cost function is: J k ={j|j0+0.1*(k-1)*(j max -j0)<j≤j0+0.1*k*(j max -j0)},k=1,2,...,n k is the interval number; j0 is the minimum control energy cost of the fault-free system.

5. The spacecraft autonomous reconstruction method according to claim 1, characterized in that: The Riccati equation in step (5) is:

6. The spacecraft autonomous reconstruction method according to claim 1, characterized in that: B f B0*diag(μ) 7. The spacecraft autonomous reconstruction method according to claim 1, characterized in that: When solving the Riccati equation, W f is the solution of the Riccati equation, when j f ≤j max When , the fault f(μ) is said to be reconfigurable.

8. An electronic device comprising: processor; as well as a memory for storing computer program instructions; When the computer program instructions are loaded and executed by the processor, the processor performs the method according to any one of claims 1 to 7.

9. A computer-readable storage medium having computer program instructions stored thereon, wherein when the computer program instructions are loaded and executed by a processor, the processor is caused to execute the method according to any one of claims 1 to 7.

10. A computer program product stored on a non-transitory computer readable medium, the computer program product comprising a program code for carrying out the method according to any one of claims 1 to 7.

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