This paper studies the leader-following attitude coordination problems of multiple spacecraft in the presence of inertia parameter uncertainties. To achieve attitude coordination in the situation that even the leader&...This paper studies the leader-following attitude coordination problems of multiple spacecraft in the presence of inertia parameter uncertainties. To achieve attitude coordination in the situation that even the leader's attitude is only applicable to a part of the following spacecraft, a nonlinear attitude observer is proposed to obtain an accurate estimation of the leader's attitude and angular velocity for all the followers. In addition, a distributed control scheme based on noncertainty equivalence principle is presented for multiple spacecraft' attitude synchronization. With a dynamic scaling, attitude consensus can be achieved asymptotically without any information of the bounds of the uncertain inertia parameters. Furthermore, once the estimations of inertia parameters reach their ideal values, the estimation process will stop and the ideal value of inertia parameter will be held. This is a special advantage of parameter estimation method based on non-certainty equivalence. Numerical simulations are presented to demonstrate that the proposed non-certainty equivalence-based method requires smaller control toque and converges faster compared with the certainty equivalence-based method.展开更多
To comprehensively assess fi＇actionated spacecraft, an assessment tool is developed based on lifecycle simulation under uncertainty driven by modular evolutionary stochastic models. First, fractionated spacecraft nom...To comprehensively assess fi＇actionated spacecraft, an assessment tool is developed based on lifecycle simulation under uncertainty driven by modular evolutionary stochastic models. First, fractionated spacecraft nomenclature and architecture are clarified, and assessment criteria are analyzed. The mean and standard deviation of risk adjusted lifecycle cost and net present value （NPV） are defined as assessment metrics. Second, fractionated spacecraft sizing models are briefly described, followed by detailed discussion on risk adjusted lifecycle cost and NPV models. Third, uncertainty sources over fractionated spacecraft life- cycle are analyzed and modeled with probability theory. Then the chronological lifecycle simulation process is expounded, and simulation modules are developed with object oriented methodology to build up the assessment tool. The preceding uncertainty models are integrated in these simulation modules, hence the random object status can be simulated and evolve with lifecycle timeline. A case study to investigate the fractionated spacecraft for a hypothetical earth observation mission is carried out with the proposed assessment tool, and the results show that fractionation degree and launch manifest have great influence on cost and NPV, and generally fractionated spacecraft is more advanced than its monolithic counterpart under uncertainty effect. Finally, some conclusions are given and future research topics are highlighted.展开更多
This paper presents a new device integrating a nonlinear vibration absorber with a levitation magnetoelectric energy harvester for whole-spacecraft systems. This device effectively reduces vibration and has a stronger...This paper presents a new device integrating a nonlinear vibration absorber with a levitation magnetoelectric energy harvester for whole-spacecraft systems. This device effectively reduces vibration and has a stronger energy harvesting capability than the existing systems. It harvests energy from a wide frequency range and has a high output voltage. The harvested energy is determined by magnetic field strength, excitation frequency, and resistive load. The change in the magnetic field strength has the least impact on the output voltage. The vibration reduction effects and harvested energy of the system are analyzed with an approximate analytical method that combines the harmonic balance approach and the pseudo-arclength continuation algorithm. The results of the Runge-Kutta method are nearly consistent with those of the approximate analytical method. Moreover, the effects of the excitation frequency, resistive load, and parameters of the nonlinear energy sink on the system vibration response and energy harvesting are analyzed.展开更多
This paper presents a discrete-time attitude control strategy with equi-global practical stabilizability for aligning the attitude of multiple spacecraft to a predesigned configuration according to a time-variant refe...This paper presents a discrete-time attitude control strategy with equi-global practical stabilizability for aligning the attitude of multiple spacecraft to a predesigned configuration according to a time-variant reference.By utilizing the interference of the wireless channel,the communication scheme designed in this paper can save communication resources,amount of computation,and energy proportionally to the number of spacecraft.The exact discrete-time model and approximate discrete-time model of the consensus-based spacecraft tracking system are given.Then the framework for the design of an event-triggered control scheme for the exact discrete-time system via its approximate models is developed,which avoids the periodic actuation,and Zeno behavior is proved to be excluded.Furthermore,the control scheme can handle the presence of the unknown fading channel.Finally,simulation results are presented to demonstrate the effectiveness of the control strategy.展开更多
In this paper,a spacecraft system is investigated.The system is formulated by partial differential equations with the initial and the boundary conditions.The spectral analysis and semigroup generation for the system a...In this paper,a spacecraft system is investigated.The system is formulated by partial differential equations with the initial and the boundary conditions.The spectral analysis and semigroup generation for the system are employed and discussed in the appropriate Hilbert spaces,and some exponential stability-type results are obtained.Finally,a significant optimal energy control is pro-posed,and existence and uniqueness of the optimal energy control are demon-strated.Eventually,an approximation theorem for minimum energy control is proved in terms of semigroup approach and geometric method.展开更多
Spacecrafts are large-scale systems characterized by various on-orbit configurations,multi-disciplinary coupling,and complex mission modes.Research and exploration on the data-driven spacecraft digital twins developme...Spacecrafts are large-scale systems characterized by various on-orbit configurations,multi-disciplinary coupling,and complex mission modes.Research and exploration on the data-driven spacecraft digital twins development methods must be carried out to satisfy various requirements such as spacecraft on-orbit condition monitoring and risk warning,fast flight conditions predictions,intelligent failure location,and virtual verification of failure.In this paper,significant progress is made in multiple key technologies,such as cyber-physical system modeling and simulation,hybrid modeling and model evolution through mechanism-data fusion,and interactive virtualreality perception and mapping.The spacecraft digital twins’model is constructed,and the spacecraft digital twin’s platform is designed and developed.Multiple digital twins’application scenarios,such as onorbit mission simulation and emulation,real-time interactive monitoring,and fast operating condition prediction,are supported.The research results are applied to the key on-orbit operation tasks,such as entering orbit,rendezvous and docking,position conversion,and astronaut exiting,enabling system-level digital operation for the sub-systems of spacecraft such as energy,power,control,and communication sub-systems.展开更多
To ensure the safety of astronauts and equipment during landing,the airbag landing system is commonly utilized to attenuate the impact response of the spacecraft.However,the complex impact dynamics and multi-disciplin...To ensure the safety of astronauts and equipment during landing,the airbag landing system is commonly utilized to attenuate the impact response of the spacecraft.However,the complex impact dynamics and multi-disciplinary coupling pose significant challenges to mission design.This paper first investigates the typical design scheme of the airbag landing system for manned spacecrafts to obtain basic insight.A comprehensive review of the past research works on the airbag landing system is then carried out from three aspects:dynamic modeling,performance optimization,and experimental study.The airbag landing system for spacecraft is a rigid-flexible-gas coupling system,which can be modeled through multi-body dynamics or finite element method.Different venting structures and optimization methods are introduced to improve the cushioning performance.Experimental setups for drop test and airbag test are developed to verify the design feasibility.Finally,this paper proposes key issues in the dynamics analysis and design optimization of the airbag landing system for future study.展开更多
Formation control of multiple spacecraft has attracted extensive research attention.However,achieving reliable performance under sensor failures remains a significant challenge.This paper develops an integrated framew...Formation control of multiple spacecraft has attracted extensive research attention.However,achieving reliable performance under sensor failures remains a significant challenge.This paper develops an integrated framework that jointly designs distributed observers and local controllers to ensure robust formation control in the presence of external disturbances and sensor malfunctions.Treating the spacecraft formation as a single interconnected system,each spacecraft constructs a distributed observer that estimates the overall system state by incorporating both its own measurements and the predicted control information shared among the spacecraft.Based on the observer estimates,a local control law is synthesized to maintain the desired formation.Rigorous theoretical analysis and numerical simulations demonstrate that the proposed integrated approach effectively guarantees formation stability and resilience against sensor failures and disturbances.展开更多
The effect of plasma and charged particle interaction with spacecraft in a low Earth orbit(LEO)environment leads to ion focusing and the formation of an ion void in the downstream region as a result of charging.Simula...The effect of plasma and charged particle interaction with spacecraft in a low Earth orbit(LEO)environment leads to ion focusing and the formation of an ion void in the downstream region as a result of charging.Simulations and investigations using a fixed potential imposed on the spacecraft showed the nonsignificance of geophysical parameter changes to ion focusing.Variation of the temperature ratio(T_(r))contributed only to local ion focusing and manifested as two-ion streamers dispersed at the upper and lower edges of the spacecraft-the outermost layers of the satellite structure at the top and bottom,respectively.A simulation involving changing the ambient plasma density(N_(p))also showed the formation of local ion focusing,in which ions were more concentrated as the density increased.Furthermore,auroral electron density(N_(ae))variation had no clear impact on ion focusing,as indicated by static two-ion structures in the wake field.However,variation of the object potential(ϕ)strongly affected ion focusing formation,leading to distortion of the initial ion void region behind the spacecraft.The formation of ion focusing in this study was subject to the electric field produced by the object potential and the ambipolar electric field resulting from plasma expansion in the downstream region.展开更多
Some ideas in the development of fault diagnosis system for spacecraft are introduced. Firstly, the architecture of spacecraft fault diagnosis is proposed hierarchically with four diagnosis frames, i.e., system level,...Some ideas in the development of fault diagnosis system for spacecraft are introduced. Firstly, the architecture of spacecraft fault diagnosis is proposed hierarchically with four diagnosis frames, i.e., system level, subsystem level, component level and element level. Secondly, a hierarchical diagnosis model is expressed with four layers, i.e., sensors layer, function layer, behavior layer and structure layer. These layers are used to work together to accomplish the fault alarm, diagnosis and localization. Thirdly, a fault-tree-oriented hybrid knowledge representation based on frame and generalized rule and its relevant reasoning strategy is put forward. Finally, a diagnosis case for spacecraft power system is exemplified combining the above with a powerful expert system development tool G2.展开更多
This paper considers a fault-tolerant control and vibration suppression problem of flexible spacecraft.The attitude dynamics is modeled by an interconnected system,in which the rigid part and the flexible part are cou...This paper considers a fault-tolerant control and vibration suppression problem of flexible spacecraft.The attitude dynamics is modeled by an interconnected system,in which the rigid part and the flexible part are coupled with each other.Such a model allows us to use the interconnected system approach to analyze the flexible spacecraft.Both distributed and decentralized observer-based fault-tolerant control schemes are developed,under which the closed-loop stability of flexible spacecraft can be ensured by using the cycle-small-gain theorem.Compared with the traditional method,this paper considers the faults occurred not only in the rigid parts,but also in the flexible parts.In addition,the application of the interconnected system approach simplifies the system model of flexible spacecraft,thereby the difficulty of theoretical analysis and engineering practice of fault-tolerant control of flexible spacecraft are greatly reduced.Simulation results show the effectiveness of the proposed methods and the comparison of different fault-tolerant control approach.展开更多
This paper investigates the cooperative tracking control problem of Electromagnetic Formation Spacecraft(EMFS)on elliptical orbit.The actuator saturation and topology switching problems exist in formation cooperative ...This paper investigates the cooperative tracking control problem of Electromagnetic Formation Spacecraft(EMFS)on elliptical orbit.The actuator saturation and topology switching problems exist in formation cooperative tracking control.The proposed novel adaptive consensus protocol addresses this problem by utilizing both synchronous and asynchronous topology switching.Firstly,to enhance the robustness of the system and minimize the impact of time-varying parameters on the control algorithm,the controller gain is determined through solving the Adaptive Riccati Differential Equation(ARDE).Secondly,a three-layer network communication structure with mirror nodes is constructed,in which different control input saturation levels are designed according to the correlation with the leader.Then,the Average Dwell Time(ADT)switching technique is utilized to generate the control switching signal,ensuring that the topology maintains a directed spanning tree when the switching signal condition is satisfied.Finally,simulation results validate the theoretical findings and provide a comparison with other methods,demonstrating the superiority of the proposed approach.展开更多
For the improvement of accuracy and better fault-tolerant performance,a global position system(GPS)/vision navigation(VISNAV)integrated relative navigation and attitude determination approach is presented for ultra-cl...For the improvement of accuracy and better fault-tolerant performance,a global position system(GPS)/vision navigation(VISNAV)integrated relative navigation and attitude determination approach is presented for ultra-close spacecraft formation flying.Onboard GPS and VISNAV system are adopted and a federal Kalman filter architecture is used for the total navigation system design.Simulation results indicate that the integrated system can provide a total improvement of relative navigation and attitude estimation performance in accuracy and fault-tolerance.展开更多
A control strategy combining feedforward control and feedback control is presented for the optimal deployment of a spacecraft solar array system with the initial state uncertainty. A dynamic equation of the spacecraft...A control strategy combining feedforward control and feedback control is presented for the optimal deployment of a spacecraft solar array system with the initial state uncertainty. A dynamic equation of the spacecraft solar array system is established under the assumption that the initial linear momentum and angular momentum of the system are zero. In the design of feedforward control, the dissipation energy of each revolute joint is selected as the performance index of the system. A Legendre pseudospectral method(LPM) is used to transform the optimal control problem into a nonlinear programming problem. Then, a sequential quadratic programming algorithm is used to solve the nonlinear programming problem and offline generate the optimal reference trajectory of the system. In the design of feedback control, the dynamic equation is linearized along the reference trajectory in the presence of initial state errors. A trajectory tracking problem is converted to a two-point boundary value problem based on Pontryagin’s minimum principle. The LPM is used to discretize the two-point boundary value problem and transform it into a set of linear algebraic equations which can be easily calculated. Then, the closed-loop state feedback control law is designed based on the resulting optimal feedback control and achieves good performance in real time. Numerical simulations demonstrate the feasibility and effectiveness of the proposed control strategy.展开更多
An integrated simulation system for solar sail spacecraft with individually controllable elements(SSICE)is investigated in this paper,including the modelling of power management,thermal control,attitude control,umbra ...An integrated simulation system for solar sail spacecraft with individually controllable elements(SSICE)is investigated in this paper,including the modelling of power management,thermal control,attitude control,umbra prediction,and orbit prediction subsystems.Considering the self-control and reactivity subsystems,an agent based method is applied to develop the subsystem models.Each subsystem is an individual agent component,which manages itself autonomously and reacts to the requirements from other agents.To reduce computing burden on a specified computer and improve the suitability and flexibility of the integrated simulation system,a distributed framework is employed in the system by deploying agent components on different computers.The data transmission among agents is based on the transmission control protocol/Internet protocol(TCP/IP).A practical example of sun pointing is used to test the operating effect of the integrated system and the working condition of subsystems.The simulation results verify that the integrated system has higher sun pointing accuracy,quicker dynamical response to variations of the lighting,attitude and temperature and fewer computing resources with effective and accurate subsystems.The integrated system proposed in this paper can be applied to solar sail design,operation,and mission planning.展开更多
The problem of robust global stabilization of a spacecraft circular orbit rendezvous system with input saturation and inputadditive uncertainties is studied in this paper. The relative models with saturation nonlinear...The problem of robust global stabilization of a spacecraft circular orbit rendezvous system with input saturation and inputadditive uncertainties is studied in this paper. The relative models with saturation nonlinearity are established based on ClohesseyWiltshire equation. Considering the advantages of the recently developed parametric Lyapunov equation-based low gain feedback design method and an existing high gain scheduling technique, a new robust gain scheduling controller is proposed to solve the robust global stabilization problem. To apply the proposed gain scheduling approaches, only a scalar nonlinear equation is required to be solved.Different from the controller design, simulations have been carried out directly on the nonlinear model of the spacecraft rendezvous operation instead of a linearized one. The effectiveness of the proposed approach is shown.展开更多
FSC （Fractionated Spacecraft Cluster） is a kind of loosely distributed space system which is comprised of multiple physically independent spacecrafts orbiting closely and interactively communicating via wireless net...FSC （Fractionated Spacecraft Cluster） is a kind of loosely distributed space system which is comprised of multiple physically independent spacecrafts orbiting closely and interactively communicating via wireless network. Spaceborne ad-hoc network, as the physical infrastructure for information exchanging, is one of the enabling technologies of FSC. The demonstration of FSC flying supported by ad-hoc network is worth for the sake of proving the rationality of FSC and seeking technological improvements. Considering this, a NNP （Network Node Prototype） for spaceborne ad-hoc network is developed in this paper, which transmits the information required by the FSC cooperation. Four NNPs are then built up and collaborated into a hardware-in-loop simulation system, in which a typical loose satellite cluster flying mission was performed. The simulation results showed that the NNPs can support the inter-satellite communication for satellite cluster flying.展开更多
The fuel slosh in the storage tanks affects the attitude dynamics of the liquid-filled spacecraft during orbit transferring. To describe the interactions between the fuel slosh dynamics and the spacecraft attitude dyn...The fuel slosh in the storage tanks affects the attitude dynamics of the liquid-filled spacecraft during orbit transferring. To describe the interactions between the fuel slosh dynamics and the spacecraft attitude dynamics, a novel nonlinear dynamic model for three-axis liquid-filled spacecraft is presented, and in this paper, the multi-body dynamics method is utilized. In this model, the fuel slosh is represented by the motions of an equivalent sphere pendulum, and the fuel slosh is underactuated. The proposed dynamics model meets the demand of attitude controller design of liquid-filled spacecraft. Then, a nonlinear proportional-plus-derivative (PD) type controller is designed for the proposed model based on the Lyapunov direct approach. This controller can suppress the fuel slosh and stabilize the attitude of the liquid-filled spacecraft. Numerical simulations are presented to verify the effectiveness of the proposed nonlinear dynamic model and the designed underactuated controller when compared with the conventional control scheme.展开更多
In this paper, forced response of fluid-spacecraft coupling system and force and moment of acting on rect-angular container are studied. Firsily, the interrelation between the generaized coordinates of fluid velocity ...In this paper, forced response of fluid-spacecraft coupling system and force and moment of acting on rect-angular container are studied. Firsily, the interrelation between the generaized coordinates of fluid velocity potential function and surface wave-height function is derived for liearized eqqations describing motion of contained fluid.The drnamical equations of coupling system is obtained by Lagrangian formulation. These equations provides some in-sights of fluid-spacecraft coupling characteristics.It is not in the sense of the whole modal mass that the fluid sloshing of corresponding order is excited by the vibration of the spacecratt.Then, the force and moment of the fiuid on the container are derived and discussed in detal. Latly, numerical simulation and conclusions are given.展开更多
Thrust-vectoring capability has become a critical feature for propulsion systems as space missions move from static to dynamic.Thrust-vectoring is a well-developed area of rocket engine science.For electric propulsion...Thrust-vectoring capability has become a critical feature for propulsion systems as space missions move from static to dynamic.Thrust-vectoring is a well-developed area of rocket engine science.For electric propulsion,however,it is an evolving field that has taken a new leap forward in recent years.A review and analysis of thrust-vectoring schemes for electric propulsion systems have been conducted.The scope of this review includes thrust-vectoring schemes that can be implemented for electrostatic,electromagnetic,and beam-driven thrusters.A classification of electric propulsion schemes that provide thrust-vectoring capability is developed.More attention is given to schemes implemented in laboratory prototypes and flight models.The final part is devoted to a discussion on the suitability of different electric propulsion systems with thrust-vectoring capability for modern space mission operations.The thrust-vectoring capability of electric propulsion is necessary for inner and outer space satellites,which are at a disadvantage with conventional unidirectional propulsion systems due to their limited maneuverability.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11402200,11502203)
文摘This paper studies the leader-following attitude coordination problems of multiple spacecraft in the presence of inertia parameter uncertainties. To achieve attitude coordination in the situation that even the leader's attitude is only applicable to a part of the following spacecraft, a nonlinear attitude observer is proposed to obtain an accurate estimation of the leader's attitude and angular velocity for all the followers. In addition, a distributed control scheme based on noncertainty equivalence principle is presented for multiple spacecraft' attitude synchronization. With a dynamic scaling, attitude consensus can be achieved asymptotically without any information of the bounds of the uncertain inertia parameters. Furthermore, once the estimations of inertia parameters reach their ideal values, the estimation process will stop and the ideal value of inertia parameter will be held. This is a special advantage of parameter estimation method based on non-certainty equivalence. Numerical simulations are presented to demonstrate that the proposed non-certainty equivalence-based method requires smaller control toque and converges faster compared with the certainty equivalence-based method.
基金Foundation items： National Natural Science Foundation of China （50975280, 61004094） Program for New Century Excellent Talents in University （NCET-08-0149）+1 种基金 Fund of Innovation by Graduate School of National University of Defense Technology （B090102） Hunan Provincial Innovation Foundation for Postgraduate, China.
文摘To comprehensively assess fi＇actionated spacecraft, an assessment tool is developed based on lifecycle simulation under uncertainty driven by modular evolutionary stochastic models. First, fractionated spacecraft nomenclature and architecture are clarified, and assessment criteria are analyzed. The mean and standard deviation of risk adjusted lifecycle cost and net present value （NPV） are defined as assessment metrics. Second, fractionated spacecraft sizing models are briefly described, followed by detailed discussion on risk adjusted lifecycle cost and NPV models. Third, uncertainty sources over fractionated spacecraft life- cycle are analyzed and modeled with probability theory. Then the chronological lifecycle simulation process is expounded, and simulation modules are developed with object oriented methodology to build up the assessment tool. The preceding uncertainty models are integrated in these simulation modules, hence the random object status can be simulated and evolve with lifecycle timeline. A case study to investigate the fractionated spacecraft for a hypothetical earth observation mission is carried out with the proposed assessment tool, and the results show that fractionation degree and launch manifest have great influence on cost and NPV, and generally fractionated spacecraft is more advanced than its monolithic counterpart under uncertainty effect. Finally, some conclusions are given and future research topics are highlighted.
基金the National Natural Science Foundation of China (Project No. 11772205)the Training Project of Liaoning Provincial Higher Education Institutions in Domestic and Overseas (Project No. 2018LNGXGJWPY-YB008)the Scientific Research Fund of Liaoning Provincial Education Department (Project No. L201703).
文摘This paper presents a new device integrating a nonlinear vibration absorber with a levitation magnetoelectric energy harvester for whole-spacecraft systems. This device effectively reduces vibration and has a stronger energy harvesting capability than the existing systems. It harvests energy from a wide frequency range and has a high output voltage. The harvested energy is determined by magnetic field strength, excitation frequency, and resistive load. The change in the magnetic field strength has the least impact on the output voltage. The vibration reduction effects and harvested energy of the system are analyzed with an approximate analytical method that combines the harmonic balance approach and the pseudo-arclength continuation algorithm. The results of the Runge-Kutta method are nearly consistent with those of the approximate analytical method. Moreover, the effects of the excitation frequency, resistive load, and parameters of the nonlinear energy sink on the system vibration response and energy harvesting are analyzed.
基金co-supported by the Equipment Advance Research Project,China(No.50912020401)the Chinese Government Scholarship(No.201906830037)。
文摘This paper presents a discrete-time attitude control strategy with equi-global practical stabilizability for aligning the attitude of multiple spacecraft to a predesigned configuration according to a time-variant reference.By utilizing the interference of the wireless channel,the communication scheme designed in this paper can save communication resources,amount of computation,and energy proportionally to the number of spacecraft.The exact discrete-time model and approximate discrete-time model of the consensus-based spacecraft tracking system are given.Then the framework for the design of an event-triggered control scheme for the exact discrete-time system via its approximate models is developed,which avoids the periodic actuation,and Zeno behavior is proved to be excluded.Furthermore,the control scheme can handle the presence of the unknown fading channel.Finally,simulation results are presented to demonstrate the effectiveness of the control strategy.
文摘In this paper,a spacecraft system is investigated.The system is formulated by partial differential equations with the initial and the boundary conditions.The spectral analysis and semigroup generation for the system are employed and discussed in the appropriate Hilbert spaces,and some exponential stability-type results are obtained.Finally,a significant optimal energy control is pro-posed,and existence and uniqueness of the optimal energy control are demon-strated.Eventually,an approximation theorem for minimum energy control is proved in terms of semigroup approach and geometric method.
文摘Spacecrafts are large-scale systems characterized by various on-orbit configurations,multi-disciplinary coupling,and complex mission modes.Research and exploration on the data-driven spacecraft digital twins development methods must be carried out to satisfy various requirements such as spacecraft on-orbit condition monitoring and risk warning,fast flight conditions predictions,intelligent failure location,and virtual verification of failure.In this paper,significant progress is made in multiple key technologies,such as cyber-physical system modeling and simulation,hybrid modeling and model evolution through mechanism-data fusion,and interactive virtualreality perception and mapping.The spacecraft digital twins’model is constructed,and the spacecraft digital twin’s platform is designed and developed.Multiple digital twins’application scenarios,such as onorbit mission simulation and emulation,real-time interactive monitoring,and fast operating condition prediction,are supported.The research results are applied to the key on-orbit operation tasks,such as entering orbit,rendezvous and docking,position conversion,and astronaut exiting,enabling system-level digital operation for the sub-systems of spacecraft such as energy,power,control,and communication sub-systems.
基金co-supported by the National Natural Science Foundation of China(Nos.11932001,12272003,U224126)。
文摘To ensure the safety of astronauts and equipment during landing,the airbag landing system is commonly utilized to attenuate the impact response of the spacecraft.However,the complex impact dynamics and multi-disciplinary coupling pose significant challenges to mission design.This paper first investigates the typical design scheme of the airbag landing system for manned spacecrafts to obtain basic insight.A comprehensive review of the past research works on the airbag landing system is then carried out from three aspects:dynamic modeling,performance optimization,and experimental study.The airbag landing system for spacecraft is a rigid-flexible-gas coupling system,which can be modeled through multi-body dynamics or finite element method.Different venting structures and optimization methods are introduced to improve the cushioning performance.Experimental setups for drop test and airbag test are developed to verify the design feasibility.Finally,this paper proposes key issues in the dynamics analysis and design optimization of the airbag landing system for future study.
基金supported by the National Natural Science Foundation of China(62088101,62522307,62273045,U2341213)Beijing Nova Program(20230484481)。
文摘Formation control of multiple spacecraft has attracted extensive research attention.However,achieving reliable performance under sensor failures remains a significant challenge.This paper develops an integrated framework that jointly designs distributed observers and local controllers to ensure robust formation control in the presence of external disturbances and sensor malfunctions.Treating the spacecraft formation as a single interconnected system,each spacecraft constructs a distributed observer that estimates the overall system state by incorporating both its own measurements and the predicted control information shared among the spacecraft.Based on the observer estimates,a local control law is synthesized to maintain the desired formation.Rigorous theoretical analysis and numerical simulations demonstrate that the proposed integrated approach effectively guarantees formation stability and resilience against sensor failures and disturbances.
基金Kobe Universitythe National Research and Innovation Agency (BRIN)
文摘The effect of plasma and charged particle interaction with spacecraft in a low Earth orbit(LEO)environment leads to ion focusing and the formation of an ion void in the downstream region as a result of charging.Simulations and investigations using a fixed potential imposed on the spacecraft showed the nonsignificance of geophysical parameter changes to ion focusing.Variation of the temperature ratio(T_(r))contributed only to local ion focusing and manifested as two-ion streamers dispersed at the upper and lower edges of the spacecraft-the outermost layers of the satellite structure at the top and bottom,respectively.A simulation involving changing the ambient plasma density(N_(p))also showed the formation of local ion focusing,in which ions were more concentrated as the density increased.Furthermore,auroral electron density(N_(ae))variation had no clear impact on ion focusing,as indicated by static two-ion structures in the wake field.However,variation of the object potential(ϕ)strongly affected ion focusing formation,leading to distortion of the initial ion void region behind the spacecraft.The formation of ion focusing in this study was subject to the electric field produced by the object potential and the ambipolar electric field resulting from plasma expansion in the downstream region.
文摘Some ideas in the development of fault diagnosis system for spacecraft are introduced. Firstly, the architecture of spacecraft fault diagnosis is proposed hierarchically with four diagnosis frames, i.e., system level, subsystem level, component level and element level. Secondly, a hierarchical diagnosis model is expressed with four layers, i.e., sensors layer, function layer, behavior layer and structure layer. These layers are used to work together to accomplish the fault alarm, diagnosis and localization. Thirdly, a fault-tree-oriented hybrid knowledge representation based on frame and generalized rule and its relevant reasoning strategy is put forward. Finally, a diagnosis case for spacecraft power system is exemplified combining the above with a powerful expert system development tool G2.
基金supported by National Natural Science Foundation of China(Nos.61622304,61773201)Natural Science Foundation of Jiangsu Province,China(No.BK20160035)Fundamental Research Funds for the Central Universities,China(No.NE2015002)。
文摘This paper considers a fault-tolerant control and vibration suppression problem of flexible spacecraft.The attitude dynamics is modeled by an interconnected system,in which the rigid part and the flexible part are coupled with each other.Such a model allows us to use the interconnected system approach to analyze the flexible spacecraft.Both distributed and decentralized observer-based fault-tolerant control schemes are developed,under which the closed-loop stability of flexible spacecraft can be ensured by using the cycle-small-gain theorem.Compared with the traditional method,this paper considers the faults occurred not only in the rigid parts,but also in the flexible parts.In addition,the application of the interconnected system approach simplifies the system model of flexible spacecraft,thereby the difficulty of theoretical analysis and engineering practice of fault-tolerant control of flexible spacecraft are greatly reduced.Simulation results show the effectiveness of the proposed methods and the comparison of different fault-tolerant control approach.
基金funded by the National Natural Science Foundation of China(No.6200326)。
文摘This paper investigates the cooperative tracking control problem of Electromagnetic Formation Spacecraft(EMFS)on elliptical orbit.The actuator saturation and topology switching problems exist in formation cooperative tracking control.The proposed novel adaptive consensus protocol addresses this problem by utilizing both synchronous and asynchronous topology switching.Firstly,to enhance the robustness of the system and minimize the impact of time-varying parameters on the control algorithm,the controller gain is determined through solving the Adaptive Riccati Differential Equation(ARDE).Secondly,a three-layer network communication structure with mirror nodes is constructed,in which different control input saturation levels are designed according to the correlation with the leader.Then,the Average Dwell Time(ADT)switching technique is utilized to generate the control switching signal,ensuring that the topology maintains a directed spanning tree when the switching signal condition is satisfied.Finally,simulation results validate the theoretical findings and provide a comparison with other methods,demonstrating the superiority of the proposed approach.
文摘For the improvement of accuracy and better fault-tolerant performance,a global position system(GPS)/vision navigation(VISNAV)integrated relative navigation and attitude determination approach is presented for ultra-close spacecraft formation flying.Onboard GPS and VISNAV system are adopted and a federal Kalman filter architecture is used for the total navigation system design.Simulation results indicate that the integrated system can provide a total improvement of relative navigation and attitude estimation performance in accuracy and fault-tolerance.
基金supported by the National Natural Science Foundation of China(Nos.11732005 and11472058)
文摘A control strategy combining feedforward control and feedback control is presented for the optimal deployment of a spacecraft solar array system with the initial state uncertainty. A dynamic equation of the spacecraft solar array system is established under the assumption that the initial linear momentum and angular momentum of the system are zero. In the design of feedforward control, the dissipation energy of each revolute joint is selected as the performance index of the system. A Legendre pseudospectral method(LPM) is used to transform the optimal control problem into a nonlinear programming problem. Then, a sequential quadratic programming algorithm is used to solve the nonlinear programming problem and offline generate the optimal reference trajectory of the system. In the design of feedback control, the dynamic equation is linearized along the reference trajectory in the presence of initial state errors. A trajectory tracking problem is converted to a two-point boundary value problem based on Pontryagin’s minimum principle. The LPM is used to discretize the two-point boundary value problem and transform it into a set of linear algebraic equations which can be easily calculated. Then, the closed-loop state feedback control law is designed based on the resulting optimal feedback control and achieves good performance in real time. Numerical simulations demonstrate the feasibility and effectiveness of the proposed control strategy.
基金This work was supported by the National Natural Science Foundation of China(11772024).
文摘An integrated simulation system for solar sail spacecraft with individually controllable elements(SSICE)is investigated in this paper,including the modelling of power management,thermal control,attitude control,umbra prediction,and orbit prediction subsystems.Considering the self-control and reactivity subsystems,an agent based method is applied to develop the subsystem models.Each subsystem is an individual agent component,which manages itself autonomously and reacts to the requirements from other agents.To reduce computing burden on a specified computer and improve the suitability and flexibility of the integrated simulation system,a distributed framework is employed in the system by deploying agent components on different computers.The data transmission among agents is based on the transmission control protocol/Internet protocol(TCP/IP).A practical example of sun pointing is used to test the operating effect of the integrated system and the working condition of subsystems.The simulation results verify that the integrated system has higher sun pointing accuracy,quicker dynamical response to variations of the lighting,attitude and temperature and fewer computing resources with effective and accurate subsystems.The integrated system proposed in this paper can be applied to solar sail design,operation,and mission planning.
基金supported by the Innovative Team Program ofthe National Natural Science Foundation of China(No.61021002)National Basic Research Program of China(973 Program)(No.2012CB821205)
文摘The problem of robust global stabilization of a spacecraft circular orbit rendezvous system with input saturation and inputadditive uncertainties is studied in this paper. The relative models with saturation nonlinearity are established based on ClohesseyWiltshire equation. Considering the advantages of the recently developed parametric Lyapunov equation-based low gain feedback design method and an existing high gain scheduling technique, a new robust gain scheduling controller is proposed to solve the robust global stabilization problem. To apply the proposed gain scheduling approaches, only a scalar nonlinear equation is required to be solved.Different from the controller design, simulations have been carried out directly on the nonlinear model of the spacecraft rendezvous operation instead of a linearized one. The effectiveness of the proposed approach is shown.
文摘FSC （Fractionated Spacecraft Cluster） is a kind of loosely distributed space system which is comprised of multiple physically independent spacecrafts orbiting closely and interactively communicating via wireless network. Spaceborne ad-hoc network, as the physical infrastructure for information exchanging, is one of the enabling technologies of FSC. The demonstration of FSC flying supported by ad-hoc network is worth for the sake of proving the rationality of FSC and seeking technological improvements. Considering this, a NNP （Network Node Prototype） for spaceborne ad-hoc network is developed in this paper, which transmits the information required by the FSC cooperation. Four NNPs are then built up and collaborated into a hardware-in-loop simulation system, in which a typical loose satellite cluster flying mission was performed. The simulation results showed that the NNPs can support the inter-satellite communication for satellite cluster flying.
基金Sponsored by the Innovative Team Program of the National Natural Science Foundation of China ( Grant No. 61021002)
文摘The fuel slosh in the storage tanks affects the attitude dynamics of the liquid-filled spacecraft during orbit transferring. To describe the interactions between the fuel slosh dynamics and the spacecraft attitude dynamics, a novel nonlinear dynamic model for three-axis liquid-filled spacecraft is presented, and in this paper, the multi-body dynamics method is utilized. In this model, the fuel slosh is represented by the motions of an equivalent sphere pendulum, and the fuel slosh is underactuated. The proposed dynamics model meets the demand of attitude controller design of liquid-filled spacecraft. Then, a nonlinear proportional-plus-derivative (PD) type controller is designed for the proposed model based on the Lyapunov direct approach. This controller can suppress the fuel slosh and stabilize the attitude of the liquid-filled spacecraft. Numerical simulations are presented to verify the effectiveness of the proposed nonlinear dynamic model and the designed underactuated controller when compared with the conventional control scheme.
文摘In this paper, forced response of fluid-spacecraft coupling system and force and moment of acting on rect-angular container are studied. Firsily, the interrelation between the generaized coordinates of fluid velocity potential function and surface wave-height function is derived for liearized eqqations describing motion of contained fluid.The drnamical equations of coupling system is obtained by Lagrangian formulation. These equations provides some in-sights of fluid-spacecraft coupling characteristics.It is not in the sense of the whole modal mass that the fluid sloshing of corresponding order is excited by the vibration of the spacecratt.Then, the force and moment of the fiuid on the container are derived and discussed in detal. Latly, numerical simulation and conclusions are given.
基金performed at large-scale research facility"Beam-M"of Bauman Moscow State Technical University following the government task by the Ministry of Science and Higher Education of the Russian Federation(No.FSFN-2024-0007).
文摘Thrust-vectoring capability has become a critical feature for propulsion systems as space missions move from static to dynamic.Thrust-vectoring is a well-developed area of rocket engine science.For electric propulsion,however,it is an evolving field that has taken a new leap forward in recent years.A review and analysis of thrust-vectoring schemes for electric propulsion systems have been conducted.The scope of this review includes thrust-vectoring schemes that can be implemented for electrostatic,electromagnetic,and beam-driven thrusters.A classification of electric propulsion schemes that provide thrust-vectoring capability is developed.More attention is given to schemes implemented in laboratory prototypes and flight models.The final part is devoted to a discussion on the suitability of different electric propulsion systems with thrust-vectoring capability for modern space mission operations.The thrust-vectoring capability of electric propulsion is necessary for inner and outer space satellites,which are at a disadvantage with conventional unidirectional propulsion systems due to their limited maneuverability.
