The spaceborne synthetic aperture radar(SAR)sparse flight 3-D imaging technology through multiple observations of the cross-track direction is designed to form the cross-track equivalent aperture,and achieve the third...The spaceborne synthetic aperture radar(SAR)sparse flight 3-D imaging technology through multiple observations of the cross-track direction is designed to form the cross-track equivalent aperture,and achieve the third dimensionality recognition.In this paper,combined with the actual triple star orbits,a sparse flight spaceborne SAR 3-D imaging method based on the sparse spectrum of interferometry and the principal component analysis(PCA)is presented.Firstly,interferometric processing is utilized to reach an effective sparse representation of radar images in the frequency domain.Secondly,as a method with simple principle and fast calculation,the PCA is introduced to extract the main features of the image spectrum according to its principal characteristics.Finally,the 3-D image can be obtained by inverse transformation of the reconstructed spectrum by the PCA.The simulation results of 4.84 km equivalent cross-track aperture and corresponding 1.78 m cross-track resolution verify the effective suppression of this method on high-frequency sidelobe noise introduced by sparse flight with a sparsity of 49%and random noise introduced by the receiver.Meanwhile,due to the influence of orbit distribution of the actual triple star orbits,the simulation results of the sparse flight with the 7-bit Barker code orbits are given as a comparison and reference to illuminate the significance of orbit distribution for this reconstruction results.This method has prospects for sparse flight 3-D imaging in high latitude areas for its short revisit period.展开更多
Long-time integration technique is an effective way of improving target detection performance for unmanned aerial vehicle(UAV)in the passive bistatic radar(PBR),while range migration(RM)and Doppler frequency migration...Long-time integration technique is an effective way of improving target detection performance for unmanned aerial vehicle(UAV)in the passive bistatic radar(PBR),while range migration(RM)and Doppler frequency migration(DFM)may have a major effect due to the target maneuverability.This paper proposed an innovative long-time coherent integration approach,regarded as Continuous Radon-matched filtering process(CRMFP),for low-observable UAV target in passive bistatic radar.It not only mitigates the RM by collaborative research in range and velocity dimensions but also compensates the DFM and ensures the coherent integration through the matched filtering process(MFP).Numerical and real-life data following detailed analysis verify that the proposed method can overcome the Doppler mismatch influence and acquire comparable detection performance.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
Instead of foreseeing and preparing for all possible scenarios of machine failures,accidents,and other challenges arising in space missions,it appears logical to take advantage of the flexibility of additive manufactu...Instead of foreseeing and preparing for all possible scenarios of machine failures,accidents,and other challenges arising in space missions,it appears logical to take advantage of the flexibility of additive manufacturing for“in-space manufacturing”(ISM).Manned missions into space rely on complicated equipment,and their safe operation is a great challenge.Bearing in mind the absolute distance for manned missions to the Moon and Mars,the supply of spare parts for the repair and replacement of lost equipment via shipment from Earth would require too much time.With the high flexibility in design and the ability to manufacture ready-to-use components directly from a computer-aided model,additive manufacturing technologies appear to be extremely attractive in this context.Moreover,appropriate technologies are required for the manufacture of building habitats for extended stays of astronauts on the Moon and Mars,as well as material/feedstock.The capacities for sending equipment and material into space are not only very limited and costly,but also raise concerns regarding environmental issues on Earth.Accordingly,not all materials can be sent from Earth,and strategies for the use of in-situ resources,i.e.,in-situ resource utilization(ISRU),are being envisioned.For the manufacturing of both complex parts and equipment,as well as for large infrastructure,appropriate technologies for material processing in space need to be developed.展开更多
基金This work was supported by the General Design Department,China Academy of Space Technology(10377).
文摘The spaceborne synthetic aperture radar(SAR)sparse flight 3-D imaging technology through multiple observations of the cross-track direction is designed to form the cross-track equivalent aperture,and achieve the third dimensionality recognition.In this paper,combined with the actual triple star orbits,a sparse flight spaceborne SAR 3-D imaging method based on the sparse spectrum of interferometry and the principal component analysis(PCA)is presented.Firstly,interferometric processing is utilized to reach an effective sparse representation of radar images in the frequency domain.Secondly,as a method with simple principle and fast calculation,the PCA is introduced to extract the main features of the image spectrum according to its principal characteristics.Finally,the 3-D image can be obtained by inverse transformation of the reconstructed spectrum by the PCA.The simulation results of 4.84 km equivalent cross-track aperture and corresponding 1.78 m cross-track resolution verify the effective suppression of this method on high-frequency sidelobe noise introduced by sparse flight with a sparsity of 49%and random noise introduced by the receiver.Meanwhile,due to the influence of orbit distribution of the actual triple star orbits,the simulation results of the sparse flight with the 7-bit Barker code orbits are given as a comparison and reference to illuminate the significance of orbit distribution for this reconstruction results.This method has prospects for sparse flight 3-D imaging in high latitude areas for its short revisit period.
基金supported by the National Natural Science Foundation of China (Nos.51975447,52275268)National Key Research and Development Program of China (No.2021YFC2203600)+2 种基金National Defense Basic Scientific Research Program of China (No.JCKY2021210B007)the Project about Building up“Scientists+Engineers”of Shaanxi Qinchuangyuan Platform (No.2022KXJ-030)Wuhu and Xidian University Special Fund for Industry University Research Cooperation (No.XWYCXY012021-012)。
文摘Long-time integration technique is an effective way of improving target detection performance for unmanned aerial vehicle(UAV)in the passive bistatic radar(PBR),while range migration(RM)and Doppler frequency migration(DFM)may have a major effect due to the target maneuverability.This paper proposed an innovative long-time coherent integration approach,regarded as Continuous Radon-matched filtering process(CRMFP),for low-observable UAV target in passive bistatic radar.It not only mitigates the RM by collaborative research in range and velocity dimensions but also compensates the DFM and ensures the coherent integration through the matched filtering process(MFP).Numerical and real-life data following detailed analysis verify that the proposed method can overcome the Doppler mismatch influence and acquire comparable detection performance.
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.
文摘Instead of foreseeing and preparing for all possible scenarios of machine failures,accidents,and other challenges arising in space missions,it appears logical to take advantage of the flexibility of additive manufacturing for“in-space manufacturing”(ISM).Manned missions into space rely on complicated equipment,and their safe operation is a great challenge.Bearing in mind the absolute distance for manned missions to the Moon and Mars,the supply of spare parts for the repair and replacement of lost equipment via shipment from Earth would require too much time.With the high flexibility in design and the ability to manufacture ready-to-use components directly from a computer-aided model,additive manufacturing technologies appear to be extremely attractive in this context.Moreover,appropriate technologies are required for the manufacture of building habitats for extended stays of astronauts on the Moon and Mars,as well as material/feedstock.The capacities for sending equipment and material into space are not only very limited and costly,but also raise concerns regarding environmental issues on Earth.Accordingly,not all materials can be sent from Earth,and strategies for the use of in-situ resources,i.e.,in-situ resource utilization(ISRU),are being envisioned.For the manufacturing of both complex parts and equipment,as well as for large infrastructure,appropriate technologies for material processing in space need to be developed.
