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25 August 2023, Volume 43 Issue 4 Previous Issue    Next Issue

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Key technologies and progress of inertial sensors for space gravitational wave detection WU Shufan, ZHANG Qianyun, LIU Meilin, SHEN Qiang 2023, 43 (4):  1-12.  doi: 10.16708/j.cnki.1000-758X.2023.0048 Abstract ( 343 )   PDF (6507KB) ( 476 )   Save Space inertial sensor is one of the key science payloads in space gravitational wave detection mission，aiming to detect infinitesimal change in gravitational wave.The research progress，detection principle and working mechanism of the inertial sensor were introduced and discussed to illustrate its technical challenges.The key technologies of the inertial sensor design were illustrated in three aspects：capacitance displacement sensing，electrostatic feedback control and ground evaluation.Then，the development and research status of inertial sensors worldwide were reviewed and summarized.It could be seen that the residual acceleration noise was the key indicator of the inertial sensor.It reached 3×10-15m/(s2·Hz1/2) orders of magnitude abroad.There are three orders of magnitude deficit between domestic and abroad.Thus，the study on high precision space inertial sensor has great strategic and scientific significance.To meet the needs of inertial sensors in China's future space gravitational wave detection missions，the research can focus on inertial sensor control system strategy，AC actuator parameter optimization，multi-degree-of-freedom decoupling control technology，and low noise technology. Related Articles | Metrics

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A review of motion control methods of macro/micro space manipulator systems YIN Wang, WANG Xiang, WANG Wei, LIU Dongyu 2023, 43 (4):  13-23.  doi: 10.16708/j.cnki.1000-758X.2023.0049 Abstract ( 303 )   PDF (5711KB) ( 568 )   Save A single manipulator can hardly meet the growing demand for space missions.In order to improve the comprehensive performance of the manipulator system，such as rapid response，high precision and large load，several countries begin to develop macro-micro manipulator systems.The development status of macro-micro manipulators on the International Space Station and Chinese Space Station was reviewed，and the motion control methods were summarized from separated time independent control mode and coordinate control mode.When the macro-micro manipulator adopts the mode of time-separating and independent control，it can be equivalent to a flexible base manipulator system.The control algorithms of flexible structure mounted manipulator systems were researched from the perspectives of optimal reaction control，active damping control and end-point trajectory tracking control.The research provides reference for on-orbit operation of China′s space manipulator.Finally，the future research prospect of dynamic modeling and motion control of space macromicro manipulator were looked into. Related Articles | Metrics

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Hypercube satellite formation control based on ADDPG strategy MIAO Jun, TU Xinying, YIN Jianfeng, PENG Jing, LI Haijin, CHEN Ziyun 2023, 43 (4):  24-34.  doi: 10.16708/j.cnki.1000-758X.2023.0050 Abstract ( 187 )   PDF (8277KB) ( 178 )   Save For the high precision control problem of large-scale satellite formation，an attraction-based deep deterministic policy gradient（ADDPG）was proposed.Firstly，topological configuration characteristics of a hypercube topological formation were formulated，and a satellite formation dynamic model was established.Then，the virtual center of hypercube satellite formation was designed to measure the overall flight state of the formation.In order to solve the problems of exploration and expansion balance of model-free deep reinforcement learning，the ε-imitation action selection strategy method was introduced.Lastly，the satellite formation control strategy based on ADDPG was proposed.The algorithm does not depend on the environmental model.With the existing information being optimized，the probability of blind trial and error in the initial exploration of the learning model would be decreased.The simulation results show that the ADDPG strategy enables higher precision as well as lower energy consumption.Compared with the well-known algorithm，the algorithm introduced in this paper not only accelerates the formation convergence rate，but also improves the control precision by 5% and reduces the energy consumption by 7%.Thus，the effectiveness of the algorithm is verified. Related Articles | Metrics

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Source analysis of multipactor-induced low-pressure gas of microwave component in spacecraft CHEN Zeyu, WANG Rui, CUI Wanzhao 2023, 43 (4):  35-42.  doi: 10.16708/j.cnki.1000-758X.2023.0051 Abstract ( 211 )   PDF (3166KB) ( 232 )   Save The low-pressure discharge effect of microwave components is a special effect threatening the safety of space electronic components.The low pressure environment inside the component after the desorption of the adsorbed gas from the component material provides the necessary conditions for low pressure discharge.Firstly，the difference between the multipactor and the low-pressure discharge was compared，and the root cause of the destructive effect of low-pressure discharge was described.Through theoretical analysis and calculation，the desorption efficiencies of thermal and electron bombardment effects on adsorbed gases with different bond energies were compared.It is found that thermogenic desorption mainly causes the desorption of physiosorbed gases with low bond energy，and that the electron bombardment effect can cause the desorption of chemisorbed gases with high bond energy.It was elucidated that electron-induced desorption processes caused by secondary electron multiplication are the main reason for the formation of the low-pressure environment inside the on-board microwave components.Finally，the method of suppressing the low-pressure discharge effect by surface treatment of component materials and increasing the threshold of secondary electron multiplication is discussed. Related Articles | Metrics

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Simulation study on the influence of magnetic screen size on Hall thruster performance XU Zongqi, TIAN Leichao, WANG Pingyang, HUA Zhiwei, HANG Guanrong 2023, 43 (4):  43-51.  doi: 10.16708/j.cnki.1000-758X.2023.0052 Abstract ( 162 )   PDF (6134KB) ( 122 )   Save  Magnetic screen is an important part of magnetic circuit system, and its sizes have an important influence on magnetic flux density distribution.In order to explore the influence law, a low-power Hall thruster was chosen as the research object.First, the finite element software Maxwell was used to simulate the magnetic flux density distributions under different axial and radial sizes of the magnetic screens.The results showed that there was a set of dimensions that could create the best magnetic field configuration for the thruster.Then, PIC method was employed to simulate the distributions of plasma parameters at 200V anode voltage and 0.8mg/s gas flow rate in the discharge channel with the dimensions as the design standard.Finally, according to the ion velocity and ion number density distributions, the calculated thrust, anode specific impulse, and anode efficiency were respectively 6.9mN, 880s, and 41.89%.This simulation study provides a theoretical basis for magnetic field design of Hall thruster and a numerical reference for future experimental research. Related Articles | Metrics

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Research on satellite software reconfiguration method for autonomous access of task LI Xiang, GONG Jianglei, GUO Lifang, HAN Xiaodong, WANG Chao, YANG Kaifei 2023, 43 (4):  52-65.  doi: 10.16708/j.cnki.1000-758X.2023.0053 Abstract ( 190 )   PDF (11571KB) ( 168 )   Save In the field of satellite designing，the software reconfiguration method has a bad performance in security and flexibility，for which the requirements of sustainable updating and extending are obviously restrained.To solve the problem，a structure of satellite software for task-level reconfiguration was presented.Meanwhile，the typical hardware environment based on a fault-tolerant SRAM and a multiple-level design approach based on soft-bus were described，and the mechanism of task auto recovery after the computer′s restarting was studied.The data protocol of software reconfiguration was proposed to guide the engineer to generate the patch.A simulation test was conducted based on the software architecture and process of task auto accessing，the results show that the proposed method is safe and effective，which can improve the performance of satellite software in the aspect of flexibility and supply a good solution for improving the usability of the satellite software. Related Articles | Metrics

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A maximum posteriori probability criterion based multiuser detection method in space based constellation networks ZHANG Kenan, LI Xingqian, YANG Sheng, DING Kai 2023, 43 (4):  66-72.  doi: 10.16708/j.cnki.1000-758X.2023.0054 Abstract ( 110 )   PDF (2582KB) ( 66 )   Save In space based constellation network，users are allowed to enter or leave the network arbitrarily.Hence，the number，identities and transmitted data of active users vary with time and have considerable impacts on the receiver’s performance.The so-called problem of multiuser detection means identifying the identity of each active user and detecting the data transmitted by each active user.Traditional methods assume that the number of active users is equal to the maximum number of users that the network can hold.The model of traditional methods is simple and the performance is suboptimal.A maximum posteriori probability（MAP）criterion based multiuser detection method was proposed.The proposed method models the state of users as Markov chain and transforms multiuser detection into searching optimal path in grid map with BCJR algorithm.Simulation results indicate that the proposed method obtains 2.6dB and 1dB Eb/N0 gains respectively when activity detection error rate and symbol error rate reach 10-3，comparing with reference methods. Related Articles | Metrics

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Dynamic modeling and analysis of space membrane structure based on constant strain element DU Xuelin, ZHANG Kang, ZHANG Ruixiang, YE Tuo, YI Wenhui, JIANG Jiabin 2023, 43 (4):  73-84.  doi: 10.16708/j.cnki.1000-758X.2023.0055 Abstract ( 178 )   PDF (19065KB) ( 335 )   Save It is necessary to analyze the dynamic deployment performance of space membrane structures for ensuring the surface accuracy and signal gain of spacecraft composed of thin membrane structure，such as inflatable deployable antennas，mesh deployable antennas，and solar sails.The whole thin membrane reflector was discretized into many constant strain triangular elements of which the nodes could be regarded as particles by using the finite element method.Under the premise of considering the elastic potential energy of the triangular element，the equilibrium equation of the triangular element was obtained by the principle of minimum potential energy，so as to realize the transformation between the strain of the point on the element and the strain of the three oblique edges of the element.Finally，the contact model was established to prevent the contact between elements in the deployment process from happening，and the mass matrix and stiffness matrix of the structure were assembled by the discrete topology of the thin membrane reflector，and the dynamic equation was established.Based on the results the dynamic model can simulate the deployment of the membrane accurately，and can be applied to analyzing the deployment performance of the membrane structure. Related Articles | Metrics

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Grid convergence analysis for numerical simulation of propellant reposition process in vane-type surface tension tank DAI Wei, ZHANG Zhongyuan, LI Guangyu, HAN Wei 2023, 43 (4):  85-92.  doi: 10.16708/j.cnki.1000-758X.2023.0056 Abstract ( 103 )   PDF (4854KB) ( 332 )   Save In order to verify the performance of 2.67L satellite tank，a tank simulation model was established.The reposition processes of propellant at 50% and 60% filling rates were simulated.For improving the simulation efficiency，the concept of GCI index was introduced.The simulation results of 2.95million，6.25million，7.67million and 9.55million grids were compared to analyze the grid convergence of the simulation model.Through the comparison and verification of the simulation results，it was considered that the error of numerical simulation could converge and had high simulation efficiency when the number of grids was 6.25million.Based on the results，the capability of the tank propellant management device to suppress liquid sloshing was analyzed.And it is shown that the 2.67L satellite tank has good performance in anti-disturbance capability. Related Articles | Metrics

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Orbit prediction method for space station based on PPO2 algorithm of reinforcement learning LEI Qiwei, ZHANG Hongbo 2023, 43 (4):  93-103.  doi: 10.16708/j.cnki.1000-758X.2023.0057 Abstract ( 185 )   PDF (10671KB) ( 190 )   Save There are many factors affecting the atmospheric density of the thermosphere and the mechanism is complex.It is difficult to establish an accurate atmospheric model，resulting in the perturbation of atmospheric resistance，which has become one of the main factors affecting the orbit prediction accuracy of the space station.The orbit prediction method based on PPO2 algorithm of reinforcement learning was studied.The reinforcement learning network was used to modify the relevant parameters in the atmospheric model and improve the orbit prediction accuracy.Firstly，the orbital dynamics model of the space station was established，the error characteristics of the atmospheric model parameters were analyzed，and the orbital dynamics model modification scheme based on reinforcement learning was designed.PPO2 algorithm was selected as the reinforcement learning algorithm，the design of training parameters and reinforcement learning network model were completed，the training and test samples of PPO2 algorithm were generated，and the simulation training and test were completed.The simulation results show that the scheme could effectively compensate the orbit prediction error caused by the inaccuracy of atmospheric density model，and improve accuracy and efficiency of the orbit prediction of the space station. Related Articles | Metrics

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Design and simulation of two-phase thermal control system for space high power source LIU Qingzhi, YANG Changpeng, XU Kan, ZHAO Xin 2023, 43 (4):  104-110.  doi: 10.16708/j.cnki.1000-758X.2023.0058 Abstract ( 189 )   PDF (4605KB) ( 477 )   Save Scheme of pumped two-phase loop with micro-channel evaporator，phase change device and radiator was brought forward to solve the thermal control problem of high power source applied to spacecraft in the future.Simulation was conducted to research characteristics and thermal control capability of two-phase loop with Sinda/Fluint thermal analysis software.The results are consistent with prediction，and temperature of the heat sources is under control.The conclusion is drawn that excessive drive capacity of pump results in bigger temperature difference of two-phase loop by simulation.Effect of heat transfer capacity of evaporator and phase change device on thermal control system was analyzed and suggestions were given. Related Articles | Metrics

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Research on additional force strategy of alternating electromagnetic despun in radial co-linear formation LIAO Qian, SHI Yongkang, HUANG Shaohua, CHEN Jinshan 2023, 43 (4):  111-119.  doi: 10.16708/j.cnki.1000-758X.2023.0059 Abstract ( 94 )   PDF (5140KB) ( 66 )   Save Space targets such as fast spinning invalid satellites threaten the safety of satellites in orbit，and the research on efficient removal of such high-priority targets has become an inevitable trend-By discussing different despun methods，a radially distributed electromagnetic despun formation strategy based on non-uniform magnetic field was proposed，which regarded the electromagnetic additional force generated by the rotating target in the non-uniform alternating electromagnetic field as the control force，adjusted the control current through the position，and used the numerical simulation method to verify the feasibility.The simulation results show that the output current of the electromagnetic coil is controlled by the distance feedback，which can reduce the relative distance variation between the electromagnetic satellite and the target and also the propellant consumption during the electromagnetic despun process.The feasibility of the propellant-free despun strategy can be realized by the distributive electromagnetic despun formation. Related Articles | Metrics

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Single frequency cycle slip detection based on Kalman filter smoothed Doppler observation WU Wei, LIU Huicui, CAO Jianfeng, JU Bing, WANG Qianxin, WU Zhiyuan 2023, 43 (4):  120-125.  doi: 10.16708/j.cnki.1000-758X.2023.0060 Abstract ( 140 )   PDF (1981KB) ( 105 )   Save To solve the problem that the Doppler method cannot detect the cycle slips due to the low observation accuracy of the single-frequency GNSS receivers on high earth orbit（HEO）satellites，a cycle slip detection method based on the Kalman filter smoothed Doppler observations was proposed.Firstly，the Doppler observations were smoothed by Kalman filtering to reduce the influence of noise.Then，the smoothed Doppler observations and carrier phase observations were adopted by Doppler method to calculate the cycle-slip detection value which should be differenced between epochs to improve the cycle-slip detection rate.The GNSS observations data received by CE-5T1 mission return vehiclse were used.The proposed method can detect the cycle slips more accurately than the traditional Doppler method in a low signaltonoise environment，which can support the future GNSS experiments on HEO satellites. Related Articles | Metrics

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Space emitter fine feature identification based on multi-domain fusion WANG Xiaohan, YAN Yi, FAN Yanan, LI Xue, MOU Jiao 2023, 43 (4):  126-136.  doi: 10.16708/j.cnki.1000-758X.2023.0061 Abstract ( 168 )   PDF (7466KB) ( 194 )   Save Emitter identification mainly focuses on individual differences of emitters，and obtains characteristic parameters related to equipment hardware on emitter signals through signal processing means，so as to master the model and working status of emitter equipment.As communication signals become more and more complex，feature identification in a single domain cannot fully reflect the fine differences of signals，and there is a large amount of data redundancy in direct identification of signal processing results，resulting in poor identification effect.In order to improve the identification effect of space emitter，an emitter identification method was proposed based on the multi-domain feature fusion.By perfroming Hilbert-Huang transform and higher order spectrum analysis of the signal，the mean，variance，kurtosis，skewness and information entropy of the teansformed results are exteacted，SVM classifier is used to classify emitters and realize the fine feature identification of multidomain fusion.The simulation results show that the accuracy of multidomain feather fusion method can reach 95.44% under the SNR of 20dB，and that the accuracy is improved by 9.41% compared with the traditional classification method based on marginal spectrum information entropy.Compared with the classification and identification methods based on HHT marginal spectrum，marginal spectrum information entropy，bispectral projection，bispectral rectangular integral and fourth-order cumulant slice spectrum，the identification effect of the proposed method is improved. Related Articles | Metrics

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A direct measurement technique of satellite-based CO2 flux LYU Meng, ZHANG Sibo, WANG Lei, YAO Wei 2023, 43 (4):  137-148.  doi: 10.16708/j.cnki.1000-758X.2023.0062 Abstract ( 165 )   PDF (4997KB) ( 263 )   Save At present，the mainstream of global carbon flux monitoring is realized through assimilation algorithms by integrating ground-based greenhouse gas flux network and concentration measurement，satellite-based remote sensing greenhouse gas concentration and other data sources.Considering the limited coverage of in-situ measurement，a direct carbon flux measurement method was proposed.The method was based on the first order closure theory of turbulence，adopted the horizontal wind profile and CO2 concentration profile and combined with Monin-Obukhov similarity theory to directly calculate CO2 flux.The horizontal wind profile was retrieved by the dual looking lidar using the coherent Doppler wind measurement method，and the CO2 concentration profile was detected based on the differential absorption principle of the lidar.The method could achieve the current international wind measurement accuracy of 1m/s and the detection accuracy of 10-6 CO2 concentration based on the satellite platform.Through preliminary analysis of the flux model，it is found that under neutral atmospheric condition with strong carbon sources（such as near ground CO2 concentration difference>10-5），the accuracy of the CO2 flux can meet the requirements of scientific application，that is，the uncertainty of CO2 flux measurement within 25% can be achieved.In general，this method can provide large-scale CO2 flux observation data as a meaningful supplement to the in-situ measurement of ground-based carbon flux. Related Articles | Metrics