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25 June 2023, Volume 43 Issue 3 Previous Issue    Next Issue

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Opportunities and challenges of longdistance high-capacity continuous wireless power transmission LI Ming, DONG Shiwei, SHI Dele 2023, 43 (3):  1-13.  doi: 10.16708/j.cnki.1000-758X.2023.0033 Abstract ( 403 )   PDF (1058KB) ( 674 )   Save Long-distance high-capacity continuous wireless power transmission（WPT）is one of the candidate routes to realize space-based solar power exploitation and carbon neutrality.Firstly，the application demands and development opportunities were introduced with specific technical requirements for practical applications of long-distance high-capacity continuous WPT.Secondly，the international state-of-the-art research progress was reported.Then technical challenges were discussed，with respect to development trend and application needs.And toward these challenges，development suggestions were proposed. Related Articles | Metrics

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Software defined TT&C system architecture and key technology LI Chao, JIAO Yiwen, FU Shiyuan, WU Tao 2023, 43 (3):  14-24.  doi: 10.16708/j.cnki.1000-758X.2023.0034 Abstract ( 323 )   PDF (6999KB) ( 427 )   Save In order to meet the rapidly changing needs of civil and commercial aerospace TT&C and the explosive growth of TT&C tasks caused by the rapid development of small satellites and large constellations，software-defined technology，which is considered a revolutionary technology that changes the rules of the game，was introduced from the internet industry into aerospace TT&C systems，a software-defined aerospace TT&C system architecture was proposed，and a new round of technological innovation in the TT&C system was realized.Firstly，the architecture and existing problems of the traditional TT&C system were analyzed，and then the technical characteristics of the software-defined aerospace TT&C system were discussed，such as hierarchical design standards，open application interfaces，centralized system control，and flexible reorganization of basic resources.Then，the advantages of the architecture and four key technologies including standard interfaces and specifications，software-defined RF front-end，software-defined channel and softwaredefined baseband were analyzed，and the development of software-defined TT&C system was prospected.The research results show that compared with the traditional TT&C system，the software-defined aerospace TT&C system architecture can better meet the needs for TT&C resources of the growing aerospace industry. Related Articles | Metrics

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Observability analysis of satellite autonomous orbit determination with modeling and measurement errors ZHOU Bochao, LI Yong, ZHANG Ai, CUI Shihang 2023, 43 (3):  25-34.  doi: 10.16708/j.cnki.1000-758X.2023.0035 Abstract ( 169 )   PDF (4403KB) ( 200 )   Save Autonomous orbit determination for a satellite with modelling and measurement errors is concerned in this paper．It’s well known that the performance of autonomous orbit determination is greatly affected by systematic errors in the dynamic model and the measurement.One way to deal with these errors is treating them as unknown biases and estimating them with dynamic states of the satellite together.Based on k-order local weak observability theory，sufficient and necessary conditions of korder local weak observability were mathematically proved for the orbit determination system with these errors.The extended Kalman filter was applied to estimate orbital states and these systematic errors simultaneously．Simulation results show that the estimation algorithm is effective when the modeling errors and measurement errors are constant or slow time-varying for non-circular orbits. Related Articles | Metrics

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Simulation and analysis of thermal state for micronano satellite YAN Xinqing, LI Yaqi, ZHANG Chenxi, HUANGFU Zhongmin, ZHANG Ning, LIU Xuemei 2023, 43 (3):  35-42.  doi: 10.16708/j.cnki.1000-758X.2023.0036 Abstract ( 309 )   PDF (4863KB) ( 428 )   Save The satellite thermal control system achieves the purpose of controlling the temperature level and temperature stability of the star by regulating the process of heat collection，transfer and emission on the satellite.It is very important to analyze the on-orbit thermal state of the satellite and to adjust and evaluate the thermal control measures based on the analysis results.Aiming at the key problems of thermal state analysis of low-orbit micro-nano satellites，the calculation method of the extra-space heat flow experienced by the satellites in orbit was given.On this basis，the temperature influencing factors and heat transfer characteristics were considered，and the instantaneous temperature calculation model of the satellite shell，radiator，internal environment，and internal and external stand-alone units were established.Taking an LEO（low earth orbit）micro-nano satellite as an example，the simulation calculation was carried out，and the results were analyzed and discussed，which provides a fast and simple analysis method for further indepth study of the thermal control design of the satellite. Related Articles | Metrics

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Fuzzy hybrid optimization for equal reentry range return trajectory CHEN Weiyue, WANG Guojun, WANG Yang, CHEN Meng, ZHANG Zhiguo 2023, 43 (3):  43-54.  doi: 10.16708/j.cnki.1000-758X.2023.0037 Abstract ( 116 )   PDF (3037KB) ( 103 )   Save Gradient kind methods depend on initial values for reentry trajectory optimization problem.Genetic algorithm requires large population and many iterations for reentry trajectory optimization.In order to avoid the disadvantages mentioned，an improved steady state genetic algorithm combined with successive quadratic programming（GA-SQP）algorithm was proposed.For equal reentry range trajectory design problem，an initial population genic check method was designed.Also a fuzzy fitness function and an inferior gene score method were provided.The reentry overload duration limitation and bank angular velocity limitation were included.In the singularity situations of reentry point behind target point and short brake duration，constraints evaluation method was also provided for successive quadratic programming process.The improved steady state GA-SQP method proposed can be applied to equal reentry range trajectory design in variable orbit altitude situations.The improved steady state  GA-SQP method proposed is independent of initial values.Comparative simulations show that the population and iterations of improved steady state GA-SQP method are decreased.The improved steady-state GA-SQP algorithm needs 34.7% fewer iterations，and its computation speed and result precision are suitable for engineering applications. Related Articles | Metrics

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Window selection probability of LTP protocol optimization in deep space communication WANG Yan, CHENG Zijing, JIN Liang, TIAN Xiaolu, HAO Xiaoqiang, WANG Pengyu 2023, 43 (3):  55-62.  doi: 10.16708/j.cnki.1000-758X.2023.0038 Abstract ( 92 )   PDF (2457KB) ( 75 )   Save In order to satisfy the requirement of DTN（delay/disruption tolerant network）in different types and different differential transmission weight data，a window selection probability function optimized method was designed based on adaptive genetic algorithm.The method used red/green（important/unimportant）data error rate as fitness function to complete cross compilation and global optimization，which allowed important data could be selected in a higher rate and could be transmitted in a higher accuracy；on the other hand，unimportant data would not be lost and could be transmitted within excepted error rate range.The method was used in the extended window unequal fountain code coding of LTP protocol in DTN network transport layer；compared to the results of the traditional genetic algorithm，optimization algorithm of adaptive genetic algorithm could decrease the important data error rate and channel total error rate in deep space communication，which could satisfy the requirement of differential data transmission，decrease data retransmission caused by high error rate，increase data transmission efficiency and save channel resources. Related Articles | Metrics

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Design and implementation of important data protection for the Zhurong Mars rover LAN Tian, ZHU Ma, PENG Song, CHEN Baichao, JIA Yang 2023, 43 (3):  63-72.  doi: 10.16708/j.cnki.1000-758X.2023.0039 Abstract ( 227 )   PDF (3428KB) ( 272 )   Save There is very limited ground support on the Martian surface，so the Zhurong rover needs to independently realize reliable survival and efficient exploration，and important data protection is a necessary condition for the autonomous capability.Due to energy constraints，only a small amount of equipment in the rover is in longterm operation，and the distributed important data protection scheme based on the onboard information network cannot be adopted.To solve this problem，an important data protection architecture that combines distributed and centralized data protection was proposed.The system management unit（SMU）centrally stored important data and provided distributed important data services for other devices.To realize the time recovery after reset or switch，an ondevice time protection method based on multiple backup was proposed，which realized the ondevice time protection with low consumption and high reliability.To protect more timed commands in limited space，an important data protection method combining private storage area and public storage area was proposed，which effectively improves the utilization rate of storage space.Proposed important data protection scheme provides reliable business continuity guarantee for the Zhurong Mars rover under the double constraints of limited ground support and limited energy，which can provide a reference for the design of subsequent deep space probes. Related Articles | Metrics

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Digital design of power processing unit for ion electric propulsion system XIN Zhiping, GU Zhiru, WANG Chao, JIANG Yuanda, HU Jiusong 2023, 43 (3):  73-80.  doi: 10.16708/j.cnki.1000-758X.2023.0040 Abstract ( 129 )   PDF (4616KB) ( 167 )   Save In order to reduce the mass of the spacecraft，improve the service life，and meet the needs of commercial aerospace small satellite electric propulsion systems，the digital design requirements of the PPU and the design scheme of the beam power supply were summarized.The BUCK scheme and the full-bridge circuit were adopted to design beam power supply according to the requirements of high precision，high stability，and fast response of the PPU.With STM32 microcontroller as the core，digital heating power supply and beam power supply were designed to realize data acquisition and telemetry of satellite platform/ground detection equipment，and the change of output voltage parameters of power supply.The experimental results show that the control accuracy of the three digital power supplies is less than 3%，and that the digitally controlled PPU has the characteristics of flexible adjustment，which can effectively reduce the volume of the control board. Related Articles | Metrics

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Design and analysis of “contact-heat conduction” heat pipe radiator YAO Liang, WANG Suming, ZHANG Hongna, LI Xiaobin, LI Fengchen, WANG Lu, ZHAO Liang 2023, 43 (3):  81-92.  doi: 10.16708/j.cnki.1000-758X.2023.0041 Abstract ( 199 )   PDF (7319KB) ( 282 )   Save Space nuclear reactor power supply has the advantages of self-generating energy，high power density，and long service life，suitable for high-power deep space exploration missions.Aiming at the heat dissipation system in space nuclear reactor power supply，a new structure of “contact-heat conduction” heat pipe radiator was designed，a heat transfer calculation model of “divided nodes-layered coupling” was put forward，and its radiation heat dissipation performance was calculated.Taking JIMO（Jupiter icy moon orbiter）space exploration mission as the background，the performance of whole heat dissipation system was analyzed and compared.The conclusions are as follows：in order to improve the heat dissipation performance of a single radiant panel and the whole system，besides increasing the inlet temperature of NaK78，the method of increasing the circulating mass flow of NaK78 can also be adopted.For a single radiant panel，when the mass flow of NaK78 is increased from 1kg/s to 10kg/s with a fixed heat dissipation area，the heat dissipation capacity of radiant panel can be increased by 1414%;while for the whole system，when the mass flow of NaK78 is increased from 1kg/s to 10kg/s with a fixed heat dissipation capacity，the total area of radiant panel required can be reduced by 67.73%.The increase of cycle mass flow can be achieved by using the “series-parallel” combination of radiation plate connection.The JIMO heat dissipation system adopts a new type of radiating plate structure，which can reduce the total radiating area by 5906% and the total mass of the radiating plate by 4.24%.The new type of radiating plate structure has high efficiency and lightweight.The conclusions are of guiding significance in the optimal design of heat pipe radiator of space reactor power system. Related Articles | Metrics

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Finegrained ship detection based on consistency criteria of hierarchical classification ZHANG Zhengning, ZHANG Lin, WANG Yue, LI Yunfei, YANG Yunchao 2023, 43 (3):  93-104.  doi: 10.16708/j.cnki.1000-758X.2023.0042 Abstract ( 177 )   PDF (5682KB) ( 291 )   Save Hierarchical and fine-grained detection of ships is essential in both military and civilian applications.Existing fine-grained detection approaches often need part-level labeling or an attention mechanism to retrieve key features.However，they do not properly exploit the affiliation information inherent in the hierarchical categorization structure of ships to increase fine-grained detection performance.Aiming at ships' hierarchical classification，we built a multi-level consistent classification mathematical model for ships.This paper proposed a finegrained detection method and loss function based on the strict consistency criterion across multiple classification levels and created a multilevel compatible fine-grained ship detection network（MLCDet）.The experimental results show that the method is effective，robust，has low resource consumption，and can effectively utilize the affiliation between categories in the classification system to improve object detection accuracy.Without the requirement for parts annotation information，mAP is increased by 1.3 percent.At the same time，the total model parameters are only increased by 0.02 percent，while the inference speed remains unchanged. Related Articles | Metrics

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LEO satellite constellation design based on QoS DAI Cuiqin, QIN Jiepeng, XU Tao, TANG Hong 2023, 43 (3):  105-115.  doi: 10.16708/j.cnki.1000-758X.2023.0043 Abstract ( 294 )   PDF (7474KB) ( 294 )   Save The design of LEO（low earth orbit）satellite constellation is the prerequisite and key to deploy LEO satellite network.However，the uneven distribution of ground users and the unreasonable allocation of satellite resources pose a major challenge to the service quality of satellite networks.To solve the above problems，a method of LEO satellite constellation based on QoS（quality of service） was proposed by establishing a QoS metrics system.Firstly，the LEO satellite network model and constellation coverage model were established，and the metric of constellation invulnerability was defined via the building criteria of inter satellite link.Secondly，the resource matching between satellite constellation and target area users was analyzed by establishing user links and defining user matching degree.Following that，the LEO constellation design problem was established to maximize the costeffectiveness ratio under the constraints of QoS metrics.The defined QoS metrics included signal-to-noise ratio，bit error rate，invulnerability，constellation coverage rate and user matching degree.In addition，the orbital parameters of the designed LEO satellite constellation were obtained through the genetic tabu intelligent algorithm.The simulation results show that the proposed LEO satellite constellation design scheme can maximize the constellation cost-effectiveness ratio while meeting the specified QoS constraints. Related Articles | Metrics

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LEO constellation configuration design method with constant trajectory of subsatellite points ZHANG Yasheng, JIA Lu, YU Jinlong, LIANG Shuang 2023, 43 (3):  116-122.  doi: 10.16708/j.cnki.1000-758X.2023.0044 Abstract ( 373 )   PDF (5014KB) ( 461 )   Save An analytical design method for the LEO constellation configuration with constant trajectory was provided，where all satellites share a common subsatellite trajectory and the trajectory is fixed.The constellation configuration was coded with two parameters，the regressor and the number of satellites.Firstly，based on the idea of average orbital elements，an analytical model of repeat ground track orbit design was established under the condition that the harmonic order of the Earth’s non-spherical perturbation band is J4.Secondly，according to the relative motion law of the satellite and Earth，the analytical formula satisfying the common trajectory condition was established.Finally，the constellation configuration design model of the LEO constant trajectory constellation was constructed by combining the concept of repeat ground track orbit design and common trajectory design.The ultimate simulation results show that the configuration design method meets the design expectation，which verifies the effectiveness of this configuration design method.The constellation configuration is characterized by simple form，easy maintenance，and wide coverage.It guarantees the consistency of orientation between the space system and ground system，which greatly reduces the complexity of satellite-ground system cooperation. Related Articles | Metrics

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Research of dynamic beam resource scheduling of LEO constellation based on A2C algorithm LIU Wei, ZHENG Runze, ZHANG Lei, GAO Zihe, TAO Ying, CUI Kaixin 2023, 43 (3):  123-133.  doi: 10.16708/j.cnki.1000-758X.2023.0045 Abstract ( 245 )   PDF (3584KB) ( 279 )   Save The giant low-orbit constellation provided low-latency，largecapacity communication channels for user spacecraft such as manned spacecraft，space stations and remote sensing satellites，and there was a resource allocation optimizing problem of satellite beams.The intelligent optimization framework of A2C（advanced actor-critic）using discrete-time deep reinforcement learning was studied，and the beam resource scheduling algorithm that could effectively meet the needs of multi-users，dynamic and concurrent access was formed by combining the concepts of individuals and genes in genetic algorithms.Based on simulation and analysis，the proposed algorithm could be applicable in a variety of typical scenarios.The method could provide effective scheduling results for more than 3000 tasks in 20s，and the task success rate was not less than 91%.The complexity was reduced by algorithm optimization，which could save more than 45% of the time compared with traditional genetic algorithms.At the same time，the convergence problem in the traditional A2C algorithm framework was optimized，which solved the non-convergence problem in the traditional fully connected A2C algorithm.Meanwhile，the convergence speed was increased by more than 38% compared with the DQN（deep q-network）algorithm. Related Articles | Metrics

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An inter satellite routing protocol based on computing resource degree SU An, LIU Naijin, CHEN Qingxia, XIANG Xueshuang, LIU Jia 2023, 43 (3):  134-143.  doi: 10.16708/j.cnki.1000-758X.2023.0046 Abstract ( 217 )   PDF (5805KB) ( 290 )   Save With the improvement of launch technology and the expansion of the demand for space missions，LEO internet constellation has gradually become a research hotspot in the aerospace industry.Computing resource awareness at the network layer helps to build the shortest computing delay path and effectively use the node resources on the edge or path for task scheduling.The traditional networking protocol did not consider the computing power resources of neighbor nodes，it was difficult to achieve resource awareness and inter satellite collaborative networking to complete the unloading task.In order to solve the problems mentioned above，the LEO satellite network was modeled as a MANET network，and the node computing resource was introduced into the active protocol OLSR to sense the computing power，CPU，memory and load of the surrounding network nodes，and the MPR selection algorithm and routing table update algorithm were modified according to this index.Simulation results show that the proposed routing protocol reduces task computing latency by 15% to 30% in inter satellite collaborative computing，and verifies the advantages of inter satellite collaborative computing by comparing it with terrestrial cloud computing. Related Articles | Metrics

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Physical layer security technology for multi-satellite TT&C systems based on directional modulation WANG Jin, ZHANG Guoting, LIU Guangkai, Bai Zhen, WEI Huizan, SUN Jingyun, ZHAO Jiaqing 2023, 43 (3):  144-152.  doi: 10.16708/j.cnki.1000-758X.2023.0047 Abstract ( 183 )   PDF (6189KB) ( 178 )   Save For giant constellations，the space TT&C system needed to serve multiple satellites simultaneously.Due to the broadcasting characteristics of microwave，the information was visible to multiple target satellites and non-target satellites during transmission by the hemispherical coverage multi-target TT&C system.In this process，the confidential messages were easy to be intercepted and eavesdropped by non-target satellites.The directional modulation（DM）technology，as a physical layer security technology，was used to solve this problem.The DM technology was applied for the ground station multi-beam transmitter to enhance the physical layer security.To optimize the beamforming matrices and the superimposed artificial noise vector for transmitted signals，the orthogonal projection method was designed when the directions of the non-target satellites were inaccessible，and the maximum signal-to-leakage-and-noise ratio（Max-SLNR）criterion was applied when the directions of the non-target satellites were available.It follows from the simulation results that both algorithms can distort the received signal constellation pattern in the directions of the non-target satellites，while maintaining the standard constellation pattern in the directions of the target satellites.In contrast，the orthogonal projection algorithm is more suitable without the directions of the non-target satellites，to achieve the undifferentiated interception effect for non-target satellite directions.However，the Max-SLNR algorithm can directionally interfere the receivers of non-target satellites with known directions. Related Articles | Metrics