A Distributed, Event-Triggered Approach for Fine-Grained Attitude Control of Spacecraft with Low Communication Requirements

Abstract

This invention discloses a distributed, event-triggered, low-communication fine-grained attitude control method for spacecraft, aiming to overcome the problems of high communication frequency, severe resource waste, and difficulty in effectively compensating for multi-source interference in existing technologies. This method constructs a deeply coupled attitude model for the spacecraft, comprehensively considering the dynamic effects of combined interferences such as center-of-mass changes and flexural vibrations; designs an event-triggered mechanism based on changes in control signals to update control commands as needed, thereby reducing the communication frequency; and constructs an adaptive composite controller to estimate and compensate for interference and communication errors online, ensuring attitude control accuracy. In a 50-second simulation, this method triggers only 75 communications while controlling the attitude tracking error to within 5 × 10⁻⁶. ‑3 Within rad, it has the advantages of low communication load, high control precision, and strong anti-interference capability, and is suitable for distributed spacecraft systems with strict requirements for attitude stability and communication resource consumption.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of spacecraft control, and particularly relates to a distributed spacecraft low-communication attitude fine control method based on event triggering. BACKGROUND

[0002] With the increasing complexity of space missions, distributed spacecraft systems gradually become an important development direction in the fields of space networking, formation observation and on-orbit service due to their modularity, high redundancy and task reconstruction capability. However, under the distributed architecture, the controller and the actuator usually adopt wireless communication mode, which faces problems such as limited bandwidth and low link reliability, seriously affecting the accuracy and stability of the attitude control.

[0003] Traditional attitude control methods mostly adopt a periodic communication mechanism to update control instructions at each sampling period. Although it is simple to implement, it still frequently transmits data when the system state changes slowly, resulting in waste of communication resources and increased control load. Especially in bandwidth-limited or high-dynamic tasks, it is easy to cause link congestion, data delay and even system instability. In addition, spacecrafts often accompany multiple disturbances such as mass center shift, flexible appendage vibration and actuator nonlinearity during the maneuvering process. These disturbances show strong coupling characteristics and dynamically change with the task state, which puts higher requirements on the anti-interference ability and precision maintenance of the control system.

[0004] To reduce the communication burden, some studies have introduced an event-triggered control mechanism to achieve on-demand communication by setting state error or control quantity change thresholds. For example, Chinese patent (application number ZL202211178812.6) and Chinese patent (application number ZL202011334538.8) propose an error-based event-triggered strategy, which effectively reduces redundant data transmission. At the same time, to address actuator failures and structural vibrations, Chinese patent (application number ZL202110528568.0) uses adaptive control for disturbance compensation. However, the existing methods still have the following shortcomings: first, the modeling of complex disturbances such as mass center changes and flexible vibrations is not systematic; second, the efficiency of communication resource scheduling and control accuracy are difficult to balance; third, in extreme environments such as deep space exploration, the autonomous control capability is insufficient.

[0005] Therefore, there is an urgent need for a method that can achieve high-precision attitude control under low-communication conditions, which can systematically model multiple-source disturbances and dynamically compensate for disturbance effects through adaptive strategies, while optimizing communication resource utilization. SUMMARY

[0006] To solve the above technical problems, the application provides a kind of based on event trigger's distributed spacecraft low communication attitude fine control method, the mass center change, flexible structure vibration etc. Compound interference factors possibly faced by spacecraft in actual maneuvering process are considered comprehensively, event trigger mechanism is combined with adaptive compound controller design, and high-precision attitude tracking accuracy and robustness are maintained while reducing communication burden.

[0007] To achieve the above object, the application adopts the following technical solutions:

[0008] A kind of based on event trigger's distributed spacecraft low communication attitude fine control method, comprising:

[0009] Step 1, the inertia disturbance caused by mass center change and the disturbance torque generated by flexible structure vibration are considered comprehensively, and a spacecraft attitude deep coupling model is established;

[0010] Step 2, design event trigger mechanism based on control signal change, by setting relative error threshold and absolute error threshold, only trigger communication update when control signal change exceeds preset range;

[0011] Step 3, construct adaptive compound controller, adopt online adaptive learning and compound control method to compensate and suppress system disturbance and communication error caused by event trigger communication at the same time, realize accurate attitude tracking.

[0012] Secondly, the application provides an electronic device, comprising: one or more processors;Memory for storing one or more programs;Wherein, when one or more programs are executed by the one or more processors, the one or more processors realize the foregoing one kind of based on event trigger's distributed spacecraft low communication attitude fine control method.

[0013] Thirdly, the application provides a computer readable storage medium, which stores executable instructions, the instructions are executed by processor to enable processor to realize the foregoing one kind of based on event trigger's distributed spacecraft low communication attitude fine control method.

[0014] The application has the following beneficial effects:

[0015] Significantly reduce communication burden: by designing event trigger mechanism based on control signal change, only update control instruction when necessary, greatly reduce redundant data transmission, effectively alleviate the bandwidth pressure, improve system efficiency.

[0016] High-precision attitude control: the spacecraft attitude deep coupling model accurately describes the dynamic characteristics of mass center change, flexible vibration and other multi-source disturbances, combined with adaptive compound controller to compensate disturbance and communication error online, meet the demand of high-precision control.

[0017] Strong anti-interference ability: adaptive law estimates the compound interference boundary dynamically, adjusts the control parameters in real time, effectively suppresses the influence of uncertainty such as centroid deviation and structural vibration, and ensures that the system still has excellent robustness and stability under low communication conditions.

[0018] Strong engineering applicability: the method structure is clear, the parameter design is flexible, the existing distributed spacecraft control system can be effectively embedded, and it is suitable for high dynamic task scenes such as deep space exploration and polar observation, and has broad engineering application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a low-communication attitude fine control method block diagram of distributed spacecraft based on event triggering of the application;

[0020] Figure 2 It is a spacecraft attitude tracking error response graph in an embodiment of the application;

[0021] Figure 3 It is a response graph of the actuator thruster in an embodiment of the application;

[0022] Figure 4 It is a response graph of the actuator thruster in an embodiment of the application;

[0023] Figure 5 It is a comparison graph of the number of controller and actuator triggers of the method and the conventional periodic sampling control. DETAILED DESCRIPTION

[0024] The application will be further described below in combination with the drawings and embodiments.

[0025] Figure 1 A block diagram of a low-communication attitude fine control system of distributed spacecraft based on event triggering according to the application is given. The specific implementation process of the application is developed around the closed-loop control structure shown in Figure 1 , mainly including the following three core modules:

[0026] Spacecraft attitude deep coupling modeling module: a deep coupling model covering the dynamic coupling of spacecraft attitude kinematics and dynamics and multi-source compound interference is constructed. This module considers the influence of inertia disturbance caused by centroid change and additional torque generated by structural flexible vibration on system dynamic performance, and provides accurate modeling basis and disturbance channel expression for subsequent control strategy.

[0027] Event trigger mechanism design module: design the trigger condition based on the control input change, combined with the relative and absolute error threshold, when the control signal changes to the set standard, trigger the control update, realize the non-periodic on-demand communication between the controller and the actuator. This mechanism effectively reduces the frequency of redundant communication, relieves the communication bandwidth pressure, while ensuring the response accuracy and timeliness of the control closed loop.

[0028] Composite controller design module: build a controller structure integrating disturbance estimation, adaptive adjustment and virtual control signal construction. According to the system state and disturbance estimation information, this module dynamically adjusts the control gain parameters, realizes online compensation of composite disturbance and real-time control of attitude accuracy, ensures the stability of the closed loop system, and improves the cooperative ability of anti-disturbance performance and control performance.

[0029] The system realizes the accurate attitude control under the condition of multi-source composite disturbance and effectively reduces the communication burden through the cooperative operation of the above modules, and has good engineering realizability and adaptability. The key implementation steps will be described in detail in the following combined with the system structure and control process.

[0030] Step 1, considering the inertia change caused by the change of center of mass and the disturbance torque produced by the vibration of flexible structure, the spacecraft attitude deep coupling model is established;

[0031] Considering the mass center change and flexible accessory vibration problem usually appeared in the attitude maneuver of distributed spacecraft, the spacecraft attitude kinematics and dynamics equation is established as:

[0032] ,

[0033] In the formula, , , respectively represent the three-axis angular velocity vector of the spacecraft and the roll angle , pitch angle , yaw angle composed of three-axis attitude angle vector, , , is the three-axis component of , is the transpose operation of vector or matrix, is the skew-symmetric matrix of , is the derivative of ; and are represented as:

[0034] ,

[0035] ,

[0036] is the angular velocity of the spacecraft's orbit; and denote the spacecraft's moment of inertia and the distribution matrix of the thrusters, respectively, is the derivative of is the thrust vector of the actuator thrusters; and are the rigid-flex coupling matrix and the displacement vector of the flexible modes, respectively, , is the first and second derivative of The inertia uncertainty caused by the mass center change and the structural flexible vibration disturbance in the spacecraft attitude dynamics can be further described as:

[0037] ,

[0038] ,

[0039] wherein, is the principal moment of inertia of the rigid part of the spacecraft; , are the moving mass center mass matrix and the mass center offset vector related matrix, respectively, and are the damping matrix and the stiffness matrix, respectively, wherein, and denote the damping coefficient and the modal frequency of the flexible appendage, is the square of , is the dimension of the modal vector, , denotes the time.

[0040] Substituting the inertia uncertainty and the structural flexible vibration disturbance into the spacecraft attitude kinematics and dynamics equations, the spacecraft attitude deep coupling model can be established as:

[0041] ,

[0042] wherein, denote the mass center change disturbance and the flexible appendage vibration disturbance generated in the spacecraft maneuver, is the first derivative of , denotes the inverse operation of the matrix.

[0043] Step 2, design an event trigger mechanism based on the change of the control signal, set relative error threshold and absolute error threshold, and only trigger communication update when the control signal changes beyond the preset range; ​

[0044] To achieve efficient utilization of communication resources, the following event triggering mechanism is designed to reduce unnecessary communication frequency:

[0045] ,

[0046] In the formula, Indicates the controller output. For the control command signals generated by the controller, Indicates the number of thrusters; Indicates the time period With time any time within the interval , Set to 0, It is a time series; , These are all design parameters, representing the relative error threshold and the absolute error threshold, respectively. Denotes the infimum of a set. Represents the absolute value of a variable.

[0047] When the designed triggering conditions are met hour, It will be transmitted to the actuator thruster, while There is no communication transmission between the controller module and the actuator module during the time interval, which will effectively reduce the communication burden. The current output signal of the controller Quantity, For the previous moment The control signal adopted by the actuator.

[0048] To facilitate controller design, intermediate parameters can be defined:

[0049] ,

[0050] in, for The Each component. Based on the event triggering conditions, it can be verified that... hour, and .therefore, for It was established at that time. Considering... ,So In each time series Both are true, therefore:

[0051] .

[0052] The above discussion can be verified And by The definition can be further obtained as follows:

[0053] ,

[0054] In the formula, This is a symbolic function. Based on the above analysis, the relationship between the actuator and the controller can be established as follows:

[0055] ,

[0056] In the formula, multiplicative interference Additive interference ,and and They can be represented as:

[0057] ,

[0058] because This can be verified. and Bounded.

[0059] Step 3: Construct an adaptive composite controller and use an online estimation method to compensate for system disturbances and communication errors caused by event-triggered communication in real time, so as to achieve accurate attitude tracking;

[0060] To design the composite controller, the attitude tracking error of the spacecraft is first defined. ,in, Let the desired attitude angle of the spacecraft be given. A virtual control signal is designed based on the attitude tracking error. The goal is to ensure the convergence of the attitude error by having the actual angular velocity track the virtual control signal. For design parameters, for The first derivative.

[0061] Furthermore, in order to effectively compensate for the multiplicative interference caused by the triggering mechanism... Additive interference And disturbances caused by changes in the center of mass and vibrations of flexible attachments. The following definition is given:

[0062] ,

[0063] ,

[0064] In the formula, Indicates when The lower bound of the time variable, when The upper bound of the time variable, The norm of a vector or matrix. This indicates taking the eigenvalues ​​of the matrix. According to... The expression can be verified Simultaneously design adaptive laws for... and Engage in online learning:

[0065] ,

[0066] ,

[0067] In the formula, and They are respectively and The estimated value; , for and The first derivative; , These are the correction parameters for the adaptive law; , For design parameters; Defined as ,and ,in, For design parameters, for The first derivative.

[0068] Combining adaptive laws, a composite controller can be constructed as follows:

[0069] ,

[0070] In the formula, express The squared term; For design parameters; Defined as , express The squared term.

[0071] This composite controller design enables the control of multiplicative disturbances introduced by event-triggered mechanisms. Additive perturbation term And the combined disturbances caused by the combined effects of changes in the center of mass and the vibration of the flexible structure. Separate learning and collaborative compensation effectively suppress the impact of multi-source disturbances on the system's attitude control performance, ensuring the accuracy and robustness of the control system under discrete triggering and compound disturbance conditions.

[0072] To verify the effectiveness of the method described in this invention and to further explain the collaborative working mechanism of the proposed modeling method, event triggering strategy, and composite controller, a simulation experiment is conducted through a typical attitude maneuvering task scenario, and key performance indicators are analyzed.

[0073] The initial state of the distributed spacecraft is chosen as follows: rad, rad / s, the desired tracking signal is rad. The spacecraft's principal inertia matrix, moving center of mass mass matrix, and center of mass offset vector correlation matrix are set as follows:

[0074] ,

[0075] ,

[0076] in, , .

[0077] The spacecraft's actuators consist of six thrusters, and their structural matrix is ​​as follows:

[0078] .

[0079] Vibration parameters for the flexible attachment are set as follows: , rad / s, rad / s, The rigid-flexible coupling matrix is: .

[0080] The design parameters involved in the method are as follows: , , , , , The simulation results are as follows: Figures 2 to 4 As shown.

[0081] Figure 2 The response curves of the spacecraft's three-axis attitude tracking error are shown. As can be seen from the figure, the attitude error gradually converges and enters the steady-state region within approximately 15 seconds. During the steady-state phase from 20 to 50 seconds, the three-axis attitude error remains consistently stable. Within rad indicates that the designed controller, under the combined effect of adaptive law and disturbance compensation mechanism, can effectively suppress sampling errors caused by event triggering and complex disturbances in the system, and achieve high-precision attitude tracking control.

[0082] Figure 3 and Figure 4The control input responses of the six actuator thrusters during the simulation are presented. It can be seen that throughout the entire control process, the control inputs of the six thrusters remain in a constant state. Within the range of N, it meets the conventional thrust force constraint requirements, indicating that the control strategy has good executability under the constraint conditions.

[0083] Figure 5 The number of triggers for each actuator during the simulation was statistically analyzed. With a sampling period of 10 milliseconds, a traditional periodic communication mechanism would generate approximately 5000 control communications during the entire 50-second simulation. In contrast, the event-triggered mechanism proposed in this invention only triggered 75 communications, significantly reducing the communication frequency between the controller and actuators, thereby effectively alleviating the communication burden on the system.

[0084] In summary, this invention is applicable to distributed spacecraft systems that primarily rely on wireless communication, and is particularly suitable for complex missions with limited communication resources and high control precision requirements, such as polar observation, deep space exploration, and high-dynamic Earth pointing. The proposed method is engineering-feasible in terms of control system structure, execution mode, and control algorithm, and can be embedded into existing attitude control system architectures. The results of the embodiments verify the effectiveness of this invention in achieving high-precision attitude control under multi-source composite interference conditions, while significantly reducing the communication frequency of the control system, demonstrating good practicality and engineering application value.

[0085] The present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned event-triggered distributed spacecraft low-communication attitude fine control method.

[0086] The present invention provides a computer-readable storage medium storing executable instructions thereon, which, when executed by a processor, enable the processor to implement the aforementioned event-triggered distributed spacecraft low-communication attitude fine control method.

[0087] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are 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 within the protection scope of the present invention.

Claims

1. An event-triggered distributed spacecraft low communication attitude fine control method, characterized in that, The method comprises the following steps: Step 1, a spacecraft attitude deep coupling model is established by comprehensively considering inertia disturbance caused by centroid change and interference torque generated by flexible structure vibration; the model comprises: Considering the centroid change and the flexible structure vibration in the attitude maneuver of the distributed spacecraft, the kinematics and dynamics equations of the spacecraft attitude are established; The inertia uncertainty caused by the centroid change and the dynamic influence of the flexible structure vibration in the spacecraft attitude dynamics are analyzed; The inertia uncertainty and the dynamic influence of the flexible structure vibration are substituted into the kinematics and dynamics equations of the spacecraft attitude, and a spacecraft attitude deep coupling model is established; Step 2, an event-triggered mechanism based on the change of the output signal of the control channel is designed, and the communication update is triggered only when the change of the output signal of the control channel exceeds the preset range by setting the relative error threshold and the absolute error threshold; the execution process comprises: monitoring the change of the output signal of each control channel in real time; the current control channel output signal is compared with the last execution signal; when the change of any channel signal exceeds the preset threshold combination, the communication update of the channel is triggered; the channel which is not triggered to update keeps the original control instruction; Step 3, an adaptive composite controller is constructed, and an online adaptive learning and composite control method is adopted to simultaneously compensate and suppress the system disturbance and the communication error caused by the event-triggered communication, so as to realize accurate attitude tracking; the execution process comprises: a virtual control signal based on the state error is designed; a compensation control law containing disturbance estimation and parameter adaptation is constructed; the virtual control signal and the compensation control law are combined to generate the final control instruction; and the stability of the closed-loop system is ensured through the online adjustment mechanism.

2. The event-triggered distributed low communication attitude fine control method for spacecraft according to claim 1, wherein, The spacecraft attitude deep coupling model is represented as: ， wherein , denote the three-axis attitude angle vector of the spacecraft composed of roll angle , pitch angle , and yaw angle , , , are the three-axis components of , is the derivative of , is the transpose operation of a vector or matrix, is the skew-symmetric matrix of , is the derivative of , is the derivative of ; and are denoted as: ， ， the principal moment of inertia of the rigid part of the spacecraft; denotes the disturbance of the center of mass due to the spacecraft maneuver and the vibration of the flexible structure, is the first derivative of , denotes the inverse of a matrix, is the angular velocity of the orbit in which the spacecraft is located; denotes the distribution matrix of the thrusters, is the thrust vector of the actuators, the thrusters; is the rigid-flexible coupling matrix.

3. The event-triggered distributed low communication attitude fine control method for spacecraft according to claim 1, characterized in that, The event-triggered mechanism in step 2 comprises: When the designed trigger condition is met, The trigger condition is that when the designed trigger condition is met, ， wherein is the control instruction signal generated by the controller at time , is the first component of the controller's current output signal, , is the control signal adopted by the actuator at the previous time , , are design parameters, respectively the relative error threshold and the absolute error threshold, denotes any time , , , is set to 0, is a time series.

4. The event-triggered distributed low communication attitude fine control method for spacecraft according to claim 2, characterized in that, Defining an attitude tracking error for a spacecraft wherein is a desired attitude angle for the spacecraft, a virtual control signal is designed from the attitude tracking error , the desired actual angular velocity is able to track the virtual control signal to ensure the convergence of the attitude error, wherein is a design parameter, is a first derivative of ; To effectively compensate for multiplicative interference caused by the triggering mechanism , additive interference , and interference caused by the change of the center of mass and the vibration of the flexible structure , the following definitions are given: ， ， wherein denotes the lower bound of a variable when denotes the upper bound of a variable when denotes the lower bound of a variable when denotes the upper bound of a variable when denotes the norm of a vector or matrix, denotes taking the eigenvalues of a matrix; Designing adaptive laws with Online learning: ， ， wherein and are and are the estimated values of , are and are the first derivatives of , are the modified parameters of the adaptive law , are design parameters are defined as , and wherein are design parameters are the first derivatives of .

5. The event-triggered distributed low communication attitude fine control method for spacecraft according to claim 4, wherein, The composite controller is: ， wherein represents the square term of is a design parameter; is defined as , represents the square term of 6. An electronic device, comprising: It comprises: One or more processors; A memory for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors realize the event-triggered distributed spacecraft low-communication attitude fine control method according to any one of claims 1-5.

7. A computer-readable storage medium, characterized in that, The executable instructions are stored thereon, and the instructions are executed by the processor to enable the processor to realize the event-triggered distributed spacecraft low-communication attitude fine control method according to any one of claims 1-5.

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