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    Scheme design and analysis of recoverable sounding rocket reducer
    YANG Jian-Yu, YANG Xuan
    null    2019, 39 (5): 1-.   DOI: 10.16708/j.cnki.1000-758X.2019.0034
    Abstract291)      PDF(pc) (2810KB)(153)      
    In order to meet the requirements of the rapid recovery of sounding rocket and reduce the development cost,a new type of sounding rocket skirt reel deceleration program was proposed. It has light weight,changeable expansion angle,expanded resistance area and some other advantages. The aerodynamic characteristics of the supersonic sounding rocket reducer were analyzed, the external flow field was simulated and analyzed. The influence of different taper angles on the aerodynamic characteristics and overload was given. The stress and strain of the external flow field, the pressure field and the gear unit were presented. The results show that the pneumatic resistance of the gear unit is obviously related to its cone angle and has the nonlinear characteristics, and the maximum stress of the reducer is less than the allowable stress. This paper can provide reference for the design of sounding rocket and new reducer.
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    Feasibility analysis of airbreathing plasma propulsion system
    YANG Zhaolun, GUO Ning, CHEN Xuekang, YAN Nengwen, WANG Cong
    Chinese Space Science and Technology    2020, 40 (1): 54-.   DOI: 10.16708/j.cnki.1000-758X.2020.0007
    Abstract288)      PDF(pc) (1591KB)(245)      
    The airbreathing plasma propulsion system has been studied as a potential technology for longlife super low altitude flight. According to different orbital environmental conditions, the feasibility of the airbreathing plasma propulsion system was discussed by using the tubular inlet and the mechanical pressurization suction method. The analysis shows that the ratio of the total power required by the spacecraft to the windward surface should be greater than 2kW/m2, and that the specific impulse of the plasma thruster should be greater than 4×104m/s, so as to meet the requirements of pushdrag balance. It is pointed out that in order to realize the application of suction system in earth orbit, the key technology is to increase gas collection efficiency and reduce collection power consumption, while the efficiency of plasma thruster needs to be further improved.
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    Research progress of electromagnetic sail propulsion for deep space exploration
    YU Wei-Dong, WEN Xiao-Dong, ZHANG Tian-Ping, LIU Li-Juan
    null    2019, 39 (4): 43-.   DOI: 10.16708/j.cnki.1000-758X.2019.0028
    Abstract261)      PDF(pc) (5928KB)(239)      
    Electromagnetic sail, a kind of space propulsion technology driven by solar wind, has broad application prospects in deep space exploration missions that require spacecraft working for a long time due to its characteristics of no propellants or less propellants. The basic concepts and main classifications of the electromagnetic sails are introduced. The working principles, system compositions, research status of ESail,PMS and MPS are discussed and followed by the plasma magnetoshell technology. Finally, the research progress of electromagnetic sail propulsion technology is summarized, which provides research direction and development ideas for domestic research in this field.
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    Attitude and orbit coupling control for fly-around observation of multi-satellite proximity operation
    XU Ying, ZHANG Jin, YU Moyao, XU Dandan
    Chinese Space Science and Technology    2019, 39 (6): 21-.   DOI: 10.16708/j.cnki.1000-758X.2019.0046
    Abstract257)      PDF(pc) (6611KB)(148)      
    Aiming at the observation mission of multi-satellite proximity operation, dynamics models of relative attitude and orbit are established. Two kinds of desired triangular formation configurations of observation satellites in elliptical and space circular orbits are considered respectively. The desired attitude is designed that the observation satellite's line of sight always points to the target satellite. The proportional-differential control law based on the quaternion and angular velocity error feedback and an improved guidance method based on artificial potential field method are used to control the relative attitude and orbit. The simulation results show that all observation satellites can effectively track the desired relative attitude and desired relative orbit under the action of the control law. In the triangular formation configuration of space circular orbit, after starting from the same initial position, the formation configuration of three observation satellites always keeps a regular triangle. Moreover, the side length of the regular triangle increases gradually from zero to finally the desired value.
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    Preliminary design and test of attitude control system for lunar CubeSats
    YANG Chi-Hang, LIU Jiang-Kai, LONG Long- , SONG Huan, LI Long, ZHU Ling-Chao, YE Bing-Xu, CHEN Hong-Ru, ZHANG Hao
    null    2019, 39 (4): 28-.   DOI: 10.16708/j.cnki.1000-758X.2019.0026
    Abstract255)      PDF(pc) (2728KB)(180)      
    CubeSats are miniature functional satellites The increasing interest in CubeSats has uncovered the potential for planetary missions Besides, CubeSats is an excellent educational platform. The preliminary attitude control system is designed and the corresponding hardware is built using commercial products for a lunar mission employing a CubeSat constellation to provide positioning service for landers/rovers on the far side of the moon At the same time, the basic frame and necessary subsystems including the structure, power and onboard computer subsystems, and the attitude experiment platform are constructed Based on the hardware platform, the control model is deeply understood through measuring damping coefficients by experiments A PD control method is designed to control the attitude The numerical and physical simulation results match well, and the CubeSat system achieves accurate attitude maneuver.
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    Thrust and specific impulse tests of miniature gallium field emission electric propulsion thruster
    XU Ming-Ming, LIU Xin-Yu, KANG Xiao-Ming, GUO Deng-Shuai, HE Wei-Guo
    null    2019, 39 (5): 69-.   DOI: 10.16708/j.cnki.1000-758X.2019.0042
    Abstract215)      PDF(pc) (3215KB)(159)      
    The development of electric propulsion technology has promoted the research process of micro thrust measurement technology and specific impulse measurement technology. In order to evaluate the performance of the developed miniature gallium field emission electric thruster, thrust and specific impulse measurements were made. A thrust measurement platform for field emission electric thrusters was developed, the LabVIEW development was carried out and the measurement platform was calibrated and analyzed. The measured values and theoretical values of the thrust were compared through experiments. The measured values range from 3 to 28μN. In addition, using the time of flight method, the thruster′s specific impulse data under different emission currents were measured, and the specific impulse′s range is 5917-8875s.
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    High speed onboard router based on LEO constellation
    LYU Yuancao, WANG Fengchun, XU Nan, HAN Xiaodong, FENG Yanjun, XING Chuan
    Chinese Space Science and Technology    2019, 39 (6): 87-.   DOI: 10.16708/j.cnki.1000-758X.2019.0054
    Abstract215)      PDF(pc) (5344KB)(131)      
    With the explosion of the internet traffic, the IPbased large volume data transmission provided by satellite network becomes a prerequisite to integrate satellite network and terrestrial network. Onboard router,whose transmission rate and QoS (Quality of Service) determine the throughput and efficiency of the entire network,is the key facility of the satellite network. Based on the low throughput of existing onboard routers, a design of high speed onboard router for LEO (Low Earth Orbit) satellite constellation is proposed. Implementing dynamic routing into the snapshotbased routing scheme makes it possible to minimize packet drop when link failure happens. This scheme enables iterative data switching after one time route computing. By using sharedmemory mode to build switchingmemory unit, also with Spacewire and Serdes interface units deployment, the intersatellite throughput can achieve up to 51 Gbit/s in theory. Moreover, the onboard router supports IPbased transmission, which lays the foundation for integrating with terrestrial network.
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    Study on the inhibition effect of modified Allan variance on Flicker PM noise
    LIU Ying-Qian, CHEN Qiang, XUE Ren-Kui, LAN Xue-Mei, ZHANG Zhen-Zhi
    null    2019, 39 (4): 68-.   DOI: 10.16708/j.cnki.1000-758X.2019.0031
    Abstract209)      PDF(pc) (1184KB)(189)      
    In the time and frequency field, Allan variance is utilized in general to indicate frequency stability. Allan variance can not inhibit Flicker PM effectively because it′s defective algorithm. In order to reduce the impact of noise on frequency stability, frequency stability should be indicated by modified Allan variance. Modified Allan variance for inhibition mechanism of Flicker PM is analyzed. Through the satellite commonview method, the comparative data of hydrogen clock and UTC(NIM) are evaluated. Then, the noise model is used to demonstrate the results of evaluation. The effectiveness of the modified Allen variance against Flicker PM inhibition is verified.
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    High power electrodeless electromagnetic propulsion based on high density plasma: a review
    LIU Li-Juan, WEN Xiao-Dong, SUN Xin-Feng, ZHANG Tian-Ping, GUO Ning
    null    2019, 39 (5): 37-.   DOI: 10.16708/j.cnki.1000-758X.2019.0038
    Abstract206)      PDF(pc) (4869KB)(290)      
    High power electrodeless electromagnetic propulsion based on high density plasma has already become one of the most competitive core propulsion technologies in future space missions, such as deep space exploration, manned space flight, solar power station and onorbit maintenance and service. Based on the different acceleration mechanisms adopted in different electrodeless electromagnetic propulsion technologies, the propulsion performances of different electromagnetic propulsion technologies were compared.Then the field reversed electrodeless electromagnetic propulsion technology adopting the rotating magnetic field acceleration mechanism was analyzed,which has great advantages and potential in developing to super high power propulsion thruster. At last, the existing technical challenges confronted in developing this new conceptual thruster was presented, aiming at providing technical and theoretical supporting for the future development of the field reversed electrodeless electromagnetic propulsion technology.
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    Space microgravity combination and its control
    YU Shao-Hua
    null    2019, 39 (5): 49-.   DOI: 10.16708/j.cnki.1000-758X.2019.0039
    Abstract203)      PDF(pc) (1448KB)(168)      
    Space microgravity combination is an upgraded version of the tethered satellite system, a more powerful and prospective version for future applications. However, both the systems are beset with the same problem: if there is no preset control,the system′s motion is unstable. Therefore, an effective control algorithm has to be developed to make the system stable. Based on a simplified dynamic model of tethered satellite,the relationship between microgravity and dynamic inertia forces was used to deduce a very unique range rate control algorithm to stabilize the system concisely and productively. This algorithm can be applied to massdistributed, elastic and other more complex cases of tethered satellite control. It can also be successfully adopted to control inorbit rendezvous and docking missions of the space microgravity combination.
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    Investigation of the Sband electromagnetic wave attenuation by the Hall thruster plume
    YU Bo, ZHANG Min, YU Shui-Lin, KANG Xiao-Lu
    null    2019, 39 (5): 19-.   DOI: 10.16708/j.cnki.1000-758X.2019.0036
    Abstract192)      PDF(pc) (11601KB)(125)      
    The Hall thruster plume exerts an attenuation influence on Sband electromagnetic wave and plays an important role in the layout strategy of the thruster and antenna on the satellite. In order to study the law of the signal attenuation, an algorithm of geometric lightpath was established to numerically describe the transportation of electromagnetic wave in Hall plume. A rectification test of the algorithm accuracy was conducted, and the signalnoise ratios (SNR) were measured by the method of wave transmission in space. According to the test and calculation results at same operation cases, the maximum relative error was 26.1%, and the average relative error was 7.3%. The calculation results kept qualitatively consistent with the test results. Based on those, the 84 typical operation cases of the SNR attenuation of the Sband electromagnetic wave were computed. The calculation results show that the absorption by plume exerted a more remarkable effect than the reflection on signal attenuation, and that the max attenuation region covered the antenna position of 0.3-0.6m,the direction angle of 15°-30°, and the attenuation value of SNR between -7dB and -4dB. This paper provides a reference base for the layout strategy of the thruster and the antenna on satellites.
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    Development and ignition characteristics of miniature gallium field emission electric propulsion thruster
    XU Ming-Ming, KANG Xiao-Ming, GUO Deng-Shuai, LIU Xin-Yu, HE Wei-Guo
    null    2019, 39 (4): 73-.   DOI: 10.16708/j.cnki.1000-758X.2019.0032
    Abstract191)      PDF(pc) (3944KB)(190)      
    In order to meet the demand for propulsion systems of micronano spacecraft such as the cubic satellite, the first needletype miniature gallium field emission electric propulsion thruster in China was developed. The problem that gallium is difficult to fully wet the tungsten needle under vacuum environment was solved by increasing the wetting temperature. The thruster′s stable ignition was realized, and the thruster′s ignition characteristics under different wetting temperatures and different geometric parameters were tested. The relationship is obtained that the emission current increases as the wetting temperature increases, the pole spacing decreases, and the inner hole diameter of absorbing pole increases. The theoretical thrust under different emission currents is given by formula calculation.The electric field strength under different geometric parameters is obtained by simulation, and the reason why the geometric parameters affect the emission current is revealed.
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    Lossless data hiding in JPEG2000 images with code stream mapping
    ZHANG Ming-Ming, ZHOU Quan, HU Yan-Lang
    null    2019, 39 (5): 28-.   DOI: 10.16708/j.cnki.1000-758X.2019.0037
    Abstract188)      PDF(pc) (11364KB)(101)      
    Remote sensing images are compressed in JPEG2000 standard and transmitted to ground by aircraft, while some other telemetry data is needed in transmission and additional data is embedded in compressed files. The author researched JPEG2000 data structure and transformed the data part of the compressed file into an image and blocked it, and then made statistics on 256 gray values to find gray values with the most occurrences and zero occurrence. Corresponding bytes of these gray values were mapped to represent different binary secret data. Receiver extracted secret data by mapping and recovered host modified bytes. Hiding capacity has an improvement of average 500bits, PSNR of marked images are larger than 30dB,and host data can still be restored losslessly. Experimental results show that this scheme can realize lossless information carrying in JPEG2000 images and file expansion does not occur.
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    Satellite attitude control method based on deep reinforcement learning
    WANG Yue-Jiao, MA Zhong, YANG Yi-Dai, WANG Zhu-Ping, TANG Lei
    null    2019, 39 (4): 36-.   DOI: 10.16708/j.cnki.1000-758X.2019.0027
    Abstract176)      PDF(pc) (2780KB)(195)      
    Aiming at the problem of sudden changes in the attitudes encountered by satellites while performing complex tasks such as discarding a payload or capturing a target, a satellite attitude control method based on the deep reinforcement learning is proposed to restore the satellite to a stable state. Concretely, the attitude dynamics environment of the vehicle is firstly established, and the output of continuous control torque is discretized. Deep Q Network algorithm is then performed to train the autonomous attitude control of the satellite for further processing, and the optimal intelligent output of discrete behavior is rewarded with the stabilization of attitude angular velocity. Finally, the validity of the mechanism is verified by the simulation test. Results analysis illustrates that the deep reinforcement learning algorithm for satellite attitude control can stabilize satellite attitude after the satellite is disturbed by sudden random disturbance, and it can effectively solve the problem of traditional PD controller depending on the mass parameters of the controlled object. The proposed method adopts selflearning to control the satellite attitude, which has strong intelligence and universal applicability, and has a strong application potential for future intelligent control of satellites performing complex space tasks.
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    Verification on electromagnetic vector modulation of plasma flow generated in helicon plasma thruster#br#
    DING Liang, ZHENG Huiqi, PENG Yuchuan, REN Qiongying, ZHAO Hua
    Chinese Space Science and Technology    2020, 40 (4): 38-43.   DOI: 10.16708/j.cnki.1000-758X.2020.0043
    Abstract174)      PDF(pc) (10374KB)(114)      
    The electromagnetic vector modulation of electrical thruster′s flow is based on magnetic field reforming which leads to the orientation altering of plasma flow. To verify the electromagnetic vector modulation of electrical thruster, the theoretical simulation and experiments were carried out for the helicon plasma thruster (HPT). The magnetic field can be altered with electromagnetic vector modulation coils illustrated in theoretical simulation results. The plasma flow is deflected as the magnetic field is adjusted as shown in experimental results. Plasma density fluctuates according to an accessional magnetic field generated periodically. The plasma flow changes its orientation with 60 degrees at most with a modulated frequency which reaches 15Hz. The electromagnetic vector modulation for helicon plasma thruster is verified feasible.
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    1553B bus communication software based on BM3803
    HAN Chun-Hui, WANG Yu, HUANG Shu-Hua, XU Quan, ZHANG Shen, LU Yue-Lin
    null    2019, 39 (5): 61-.   DOI: 10.16708/j.cnki.1000-758X.2019.0041
    Abstract173)      PDF(pc) (5113KB)(137)      
    processor is used in a satellite ground detection equipment to simulate the bus controller in the satellite in order to detect the remote terminal, and a satellite data simulation platform with stronger realtime performance than the traditional Windows+1553B_PCI board solution is constructed. The realtime operating system μC/OSII is transplanted to BM3803, and the boardlevel support package for BM3803 is designed to ensure the onorbit software update and the task realtime. The software structure with high separation of user tasks and hardware is determined. When designing the user tasks of μC/OSII, the verification functions of BM3803 and B61580 are fully utilized to improve the software reliability. Finally, the same user task is completed with this design and the Windows+1553B_PCI board solution respectively, and the design has better realtime performance, which can meet the realtime requirements of the highlevel satellite communication protocol.
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    Emergency return analysis of hybrid trajectory based on one impulse for human lunar mission
    LYU Pengwei, SHANG Zhi, WANG Ping
    Chinese Space Science and Technology    2020, 40 (1): 1-.   DOI: 10.16708/j.cnki.1000-758X.2020.0001
    Abstract172)      PDF(pc) (3881KB)(104)      
    For human earthmoon transfer mission, emergency return trajectories are key to astronauts′ safe return to earth. Emergency return trajectories based on human translunar hybrid trajectory were proposed, considering safety the most important requirement in human earthmoon transfer mission. There are three emergent return methods,which are direct return, immediate transfer and steer by the moon, and steer by the moon and return. The characteristics of transfer time and velocity increment of the three emergent return methods were studied. The advantages and disadvantages of the three emergency return methods were analyzed, providing reference for translunar trajectory selection in subsequent human lunar exploration missions.
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    Thermalstructural coupling analysis of space inflatable
    membrane diffraction imaging structures
    SUN Xiang-Wei, XU Yan, WANG Pei-Dong, FANG Qin, ZHU Dong-Fang
    null    2019, 39 (5): 8-.   DOI: 10.16708/j.cnki.1000-758X.2019.0035
    Abstract160)      PDF(pc) (11565KB)(68)      
    With the development of space optical technology, diffraction imaging system has become a research hotspot in the field of space optics. In this paper, a structural design scheme of an inflatable membrane diffraction imaging structures is presented. Thermodynamic coupling effects of inflatable structures under the space thermal environment were studied. A coupled thermalstructural sequence analysis framework for inflatable structures was developed. The thermalstructural coupling analysis of the inflatable structure was realized by IDEAS and ANSYS secondary development technology. The transient heat transfer, thermal stress and thermal deformation of the structures in orbit were investigated. The results show that there is large thermal deformation in the inflatable support structures, but the maximum thermal stress is much less than the tensile strength of the polyimide membrane,and there is no large thermal deformation response at the center of the structures. The technology support for thermal protection design of inflatable membrane diffraction imaging structures is provided.
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    Space robot capture collision force control method based on explicit force control
    FANG Qun, CUI Ming-Ming
    null    2019, 39 (4): 1-.   DOI: 10.16708/j.cnki.1000-758X.2019.0023
    Abstract160)      PDF(pc) (6328KB)(202)      
    Aiming at the collision force control problem of space robots in capturing floating targets, the dynamic model of the space robot′s catching target and the contact collision model with the target are established. The parameters such as the closing speed of the claw and the initial position of the target are analyzed. On the basis of this, the taskfirst inverse kinematics solution method is used to design the capture force control method based on explicit force control, the collision force control method based on external force control and the collision force based on explicit force control. The control method is compared and analyzed. The results show that the collision force control method based on the explicit force control can achieve the collision force control that meets the requirements of stationarity, and the required pedestal thrust and joint control torque are small.
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    Research on unconventional dynamic problems for #br# small satellites
    BAI Zhaoguang, YANG Xinfeng, CUI Yufu, LIU Zhijia, DENG Weihua
    Chinese Space Science and Technology    2019, 39 (6): 1-.   DOI: 10.16708/j.cnki.1000-758X.2019.0044
    Abstract155)      PDF(pc) (2387KB)(105)      
    Some special dynamic problems encountered in small satellites were studied, and the corresponding solutions were developed. To solve the difficulties of analysis and test for high level shock much higher than the frequentlyused shock test standard spectrum, a method was proposed to analyze the high level shock. As for problems in strength design under random vibration for small satellites, the influence of the modal effective mass ratios and modal frequencies on quasistatic load computation was studied. The analysis shows that neglecting the coupling of modal effective masses and the coupling of modal frequencies leads to large error in quasistatic load computation under random vibration. The method for quasistatic load computation with consideration of the coupling of modal effective masses was proposed. Finally, the study on vibration reduction was carried out for a small satellite, and the vibration reduction for sine vibration and random vibration was analyzed. The calculation method of the main frequency for vibration reduction system with symmetrical installation was given.
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