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Review on strategies of space-based optical space situational awareness 被引量:8
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作者 HU Yunpeng LI Kebo +1 位作者 LIANG Yan’gang CHEN Lei 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2021年第5期1152-1166,共15页
Space-based optical(SBO)space surveillance has attracted widespread interest in the last two decades due to its considerable value in space situation awareness(SSA).SBO observation strategy,which is related to the per... Space-based optical(SBO)space surveillance has attracted widespread interest in the last two decades due to its considerable value in space situation awareness(SSA).SBO observation strategy,which is related to the performance of space surveillance,is the top-level design in SSA missions reviewed.The recognized real programs about SBO SAA proposed by the institutions in the U.S.,Canada,Europe,etc.,are summarized firstly,from which an insight of the development trend of SBO SAA can be obtained.According to the aim of the SBO SSA,the missions can be divided into general surveillance and space object tracking.Thus,there are two major categories for SBO SSA strategies.Existing general surveillance strategies for observing low earth orbit(LEO)objects and beyond-LEO objects are summarized and compared in terms of coverage rate,revisit time,visibility period,and image processing.Then,the SBO space object tracking strategies,which has experienced from tracking an object with a single satellite to tracking an object with multiple satellites cooperatively,are also summarized.Finally,this paper looks into the development trend in the future and points out several problems that challenges the SBO SSA. 展开更多
关键词 space situation awareness(SSA) space-based space surveillance space-based optical(SBO)observation strategy general surveillance space object tracking
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A novel high precision Doppler frequency estimation method based on the third-order phase-locked loop 被引量:1
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作者 Tao Deng Mao-Li Ma +1 位作者 Qing-Hui Liu Ya-Jun Wu 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2021年第9期83-90,共8页
In deep space exploration,many engineering and scientific requirements require the accuracy of the measured Doppler frequency to be as high as possible.In our paper,we analyze the possible frequency measurement points... In deep space exploration,many engineering and scientific requirements require the accuracy of the measured Doppler frequency to be as high as possible.In our paper,we analyze the possible frequency measurement points of the third-order phase-locked loop(PLL)and find a new Doppler measurement strategy.Based on this finding,a Doppler frequency measurement algorithm with significantly higher measurement accuracy is obtained.In the actual data processing,compared with the existing engineering software,the accuracy of frequency of 1 second integration is about 5.5 times higher when using the new algorithm.The improved algorithm is simple and easy to implement.This improvement can be easily combined with other improvement methods of PLL,so that the performance of PLL can be further improved. 展开更多
关键词 Doppler frequency measurement:deep space exploration:carrier tracking:phase locked loop:high precision
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Optical SDMA for applying compressive sensing in WSN 被引量:1
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作者 Xuewen Liu Song Xiao Lei Quan 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2016年第4期780-789,共10页
In order to apply compressive sensing in wireless sensor network, inside the nodes cluster classified by the spatial correlation, we propose that a cluster head adopts free space optical communication with space divis... In order to apply compressive sensing in wireless sensor network, inside the nodes cluster classified by the spatial correlation, we propose that a cluster head adopts free space optical communication with space division multiple access, and a sensor node uses a modulating retro-reflector for communication. Thus while a random sampling matrix is used to guide the establishment of links between head cluster and sensor nodes, the random linear projection is accomplished. To establish multiple links at the same time, an optical space division multiple access antenna is designed. It works in fixed beams switching mode and consists of optic lens with a large field of view(FOV), fiber array on the focal plane which is used to realize virtual channels segmentation, direction of arrival sensor, optical matrix switch and controller. Based on the angles of nodes' laser beams, by dynamically changing the route, optical matrix switch actualizes the multi-beam full duplex tracking receiving and transmission. Due to the structure of fiber array, there will be several fade zones both in the focal plane and in lens' FOV. In order to lower the impact of fade zones and harmonize multibeam, a fiber array adjustment is designed. By theoretical, simulated and experimental study, the antenna's qualitative feasibility is validated. 展开更多
关键词 wireless sensor network compressive sensing space division multiple access optical matrix switch laser beam tracking
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Fuzzy adaptive robust control for space robot considering the effect of the gravity 被引量:14
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作者 Qin Li Liu Fucai +1 位作者 Liang Lihuan Gao Jingfang 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2014年第6期1562-1570,共9页
Space robot is assembled and tested in gravity environment, and completes on-orbit service(OOS) in microgravity environment. The kinematic and dynamic characteristic of the robot will change with the variations of g... Space robot is assembled and tested in gravity environment, and completes on-orbit service(OOS) in microgravity environment. The kinematic and dynamic characteristic of the robot will change with the variations of gravity in different working condition. Fully considering the change of kinematic and dynamic models caused by the change of gravity environment, a fuzzy adaptive robust control(FARC) strategy which is adaptive to these model variations is put forward for trajectory tracking control of space robot. A fuzzy algorithm is employed to approximate the nonlinear uncertainties in the model, adaptive laws of the parameters are constructed, and the approximation error is compensated by using a robust control algorithm. The stability of the control system is guaranteed based on the Lyapunov theory and the trajectory tracking control simulation is performed. The simulation results are compared with the proportional plus derivative(PD) controller, and the effectiveness to achieve better trajectory tracking performance under different gravity environment without changing the control parameters and the advantage of the proposed controller are verified. 展开更多
关键词 Fuzzy adaptive Microgravity Robustness space robot Trajectory tracking control
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Real-time space object tracklet extraction from telescope survey images with machine learning 被引量:2
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作者 Andrea De Vittori Riccardo Cipollone +1 位作者 Pierluigi Di Lizia Mauro Massari 《Astrodynamics》 EI CSCD 2022年第2期205-218,共14页
In this study,a novel approach based on the U-Net deep neural network for image segmentation is leveraged for real-time extraction of tracklets from optical acquisitions.As in all machine learning(ML)applications,a se... In this study,a novel approach based on the U-Net deep neural network for image segmentation is leveraged for real-time extraction of tracklets from optical acquisitions.As in all machine learning(ML)applications,a series of steps is required for a working pipeline:dataset creation,preprocessing,training,testing,and post-processing to refine the trained network output.Online websites usually lack ready-to-use datasets;thus,an in-house application artificially generates 360 labeled images.Particularly,this software tool produces synthetic night-sky shots of transiting objects over a specified location and the corresponding labels:dual-tone pictures with black backgrounds and white tracklets.Second,both images and labels are downscaled in resolution and normalized to accelerate the training phase.To assess the network performance,a set of both synthetic and real images was inputted.After the preprocessing phase,real images were fine-tuned for vignette reduction and background brightness uniformity.Additionally,they are down-converted to eight bits.Once the network outputs labels,post-processing identifies the centroid right ascension and declination of the object.The average processing time per real image is less than 1.2 s;bright tracklets are easily detected with a mean centroid angular error of 0.25 deg in 75%of test cases with a 2 deg field-of-view telescope.These results prove that an ML-based method can be considered a valid choice when dealing with trail reconstruction,leading to acceptable accuracy for a fast image processing pipeline. 展开更多
关键词 space surveillance and tracking (SST) space debris tracklet telescope images machine learning(ML) U-Net
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C60-based clustering scheme for sensor management in STSS 被引量:3
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作者 Tiebing Wang Miao Li +2 位作者 Xueying Wang Wei An Yiyu Zhou 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2015年第5期993-999,共7页
Clustering-based sensor-management schemes have been widely used for various wireless sensor networks(WSNs), as they are well suited to the distributive and collaborative nature of WSN. In this paper, a C60-based clus... Clustering-based sensor-management schemes have been widely used for various wireless sensor networks(WSNs), as they are well suited to the distributive and collaborative nature of WSN. In this paper, a C60-based clustering algorithm is proposed for the specific planned network of space tracking and surveillance system(STSS), where all the sensors are partitioned into 12 clusters according to the C60(or football surface) architecture, and then a hierarchical sensor-management scheme is well designed.Finally, the algorithm is applied to a typical STSS constellation,and the simulation results show that the proposed method has better target-tracking performance than the nonclustering scheduling method. 展开更多
关键词 wireless sensor networks (WSNs) sensor manage-ment CLUSTERING C60 space tracking and surveillance system (STSS)
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