An approach to sequence planning for on-orbit assembly of large space truss structures in a multirobot environment is presented.A hierarchical representation of large space truss structures at the structural volume el...An approach to sequence planning for on-orbit assembly of large space truss structures in a multirobot environment is presented.A hierarchical representation of large space truss structures at the structural volume element level and strut level is adopted.The representation of connectivity matrix and directed graph is respectively presented at the strut level and SVE level.The multirobot environment that consists of autonomous space robots and struts is supposed.Then the multirobot serial assembly strategy,assembly states,assembly tasks and assembly sequences are described.The assembly sequence planning algorithms at the strut level and SVE level are respectively discussed.The results of the simulations show that this approach is feasible and efficient.Two extensions of this approach include more accurate assessment of the efficiency representation and improvements in planning algorithm.In the future,the assembly sequence planning of more large space truss structures and complex multirobot environments and assembly tasks will be considered.展开更多
The oscillation of large space structure(LSS)can be easily induced because of its low vibration frequency.The coupling effect between LSS vibration control and attitude control can significantly reduce the overall per...The oscillation of large space structure(LSS)can be easily induced because of its low vibration frequency.The coupling effect between LSS vibration control and attitude control can significantly reduce the overall performance of the control system,especially when the scale of flexible structure increases.This paper proposes an optimal placement method of piezoelectric stack actuators(PSAs)network which reduces the coupling effect between attitude and vibration control system.First,a spacecraft with a honeycomb-shaped telescope is designed for a resolution-critical imaging scenario.The coupling dynamics of the spacecraft is established using finite element method(FEM)and floating frame of reference formulation(FFRF).Second,a coupling-effect-reducing optimal placement criterion for PSAs based on coupling-matrix enhanced Gramian is designed to reduce the coupling effect excitation while balancing controllability.Additionally,a laddered multi-layered optimizing scheme is established to increase the speed and accuracy when solving the gigantic discrete optimization problem.Finally,the effectiveness of the proposed method is illustrated through numerical simulation.展开更多
Large steel space structures,when exposed to a harsh corrosive environment,are inevitably subjected to atmospheric corrosion and stress corrosion cracking.This paper proposes a framework for assessing the corrosion da...Large steel space structures,when exposed to a harsh corrosive environment,are inevitably subjected to atmospheric corrosion and stress corrosion cracking.This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion.The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced.The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking.Based on the results,the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.展开更多
文摘An approach to sequence planning for on-orbit assembly of large space truss structures in a multirobot environment is presented.A hierarchical representation of large space truss structures at the structural volume element level and strut level is adopted.The representation of connectivity matrix and directed graph is respectively presented at the strut level and SVE level.The multirobot environment that consists of autonomous space robots and struts is supposed.Then the multirobot serial assembly strategy,assembly states,assembly tasks and assembly sequences are described.The assembly sequence planning algorithms at the strut level and SVE level are respectively discussed.The results of the simulations show that this approach is feasible and efficient.Two extensions of this approach include more accurate assessment of the efficiency representation and improvements in planning algorithm.In the future,the assembly sequence planning of more large space truss structures and complex multirobot environments and assembly tasks will be considered.
基金supported by National Natural Science Foundation of China(No.U23B6001).
文摘The oscillation of large space structure(LSS)can be easily induced because of its low vibration frequency.The coupling effect between LSS vibration control and attitude control can significantly reduce the overall performance of the control system,especially when the scale of flexible structure increases.This paper proposes an optimal placement method of piezoelectric stack actuators(PSAs)network which reduces the coupling effect between attitude and vibration control system.First,a spacecraft with a honeycomb-shaped telescope is designed for a resolution-critical imaging scenario.The coupling dynamics of the spacecraft is established using finite element method(FEM)and floating frame of reference formulation(FFRF).Second,a coupling-effect-reducing optimal placement criterion for PSAs based on coupling-matrix enhanced Gramian is designed to reduce the coupling effect excitation while balancing controllability.Additionally,a laddered multi-layered optimizing scheme is established to increase the speed and accuracy when solving the gigantic discrete optimization problem.Finally,the effectiveness of the proposed method is illustrated through numerical simulation.
基金support from the Hong Kong Polytechnic University through its Niche Area Project in Performance-Based Structural Health Monitoring and the Fundamental Research Funds for the Central University of China(2010-II-019).
文摘Large steel space structures,when exposed to a harsh corrosive environment,are inevitably subjected to atmospheric corrosion and stress corrosion cracking.This paper proposes a framework for assessing the corrosion damage of large steel space structures subjected to both stress corrosion cracking and atmospheric corrosion.The empirical model for estimating atmospheric corrosion based on measured information is briefly introduced.The proposed framework is applied to a real large steel space structure built in the southern coastal area in China to assess its corrosion damage and investigate the effects of atmospheric corrosion on stress corrosion cracking.Based on the results,the conceptual design of the corrosion monitoring system of large steel space structures is finally conducted as the first step for a real corrosion monitoring system.
