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    25 April 2011, Volume 31 Issue 2 Previous Issue    Next Issue
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    Relative Cooperative Attitude and Position Control of Fractioned Spacecraft Based on Iterative Optimization
    ZHU Zhi-Bin, LI Guo, HE Ying-Zi, WEI Chun-Ling
    2011, 31 (2):  1-8.  doi: 10.3780/j.issn-1000-758X.2011.02.001
    Abstract ( 2958 )   PDF (382KB) ( 1695 )   Save
    In short range guidance stage, eccentric low-level continuous vector thruster and transformed torque equipment were used to maintain the close approaching and circling of specific object, and complete simultaneously orbit control and light of sight(LOS) stabilization. Relative coupling attitude and orbit dynamic model was established based on T-H equation and error quaternion. Expected relative position gaits were designed respectively for close approaching phase and circling phase. Expected attitude was computed based on LOS angles. Traditional θ-D method can only linearize dynamic equation at start point which hold limited neighbor stable area that can not cover large alteration of relative states during the process. Piecewise linearized θ-D suboptimal controller was proposed based on iterative optimal theory and utilized in relative attitude and orbit control, in which vector part of error quaternion was directly used for state feedback. Decent dimension alternation was made for coupling attitude and position state equation. Simulation results demonstrate that this method are effective.
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    Determination of the Ambiguity Search Space in Hybrid GPS/Galileo Navigation
    ZHAO Yi, GONG Cheng, DENG Ning
    2011, 31 (2):  9-15.  doi: 10.3780/j.issn.1000-758X.2011.02.002
    Abstract ( 3783 )   PDF (445KB) ( 2109 )   Save
    In order to fix the ambiguities in hybrid GPS/Galileo navigation and positioning, several conventional spacedetermining methods for least squares ambiguity decorrelation adjustment (LAMBDA) in GPS scenario were adopted in GPS/Galileo hybrid scenario. Simulation results show the conventional space-determining methods can′t meet the performance requirements for the high dimension in ambiguity vector. Compared to the conventional methods in determining LAMBDA ambiguity-search space, a new space-determining method specifically for high-dimension ambiguity vector was proposed. The simulation tests indicated that the proposed algorithm guaranteed an essential alignment of real and predefined candidate ambiguity numbers in joint  positioning mode, and hence improved the searching efficiency without scarifying success ratio in determining the phase ambiguity.
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    Fuel-optimal Precise Rendezvous Guidance Law in Elliptical Reference Orbit with J2 Perturbation
    JING Wu-Xing, CHEN Wei-Yue
    2011, 31 (2):  16-24.  doi: 10.3780/j.issn.1000-758X.2011.02.003
    Abstract ( 2849 )   PDF (564KB) ( 1785 )   Save
    For rendezvous near an elliptical reference orbit, a numerical gradient algorithm and a genetic algorithm for optimization were adopted to determine the optimal transfer time and impulses. The solutions for half-revolution and complete-revolution rendezvous were also given to eliminate the singularities. Based on the optimization algorithms, a two-impulse iteration method with linear gradient was proposed for rendezvous guidance to eliminate the impact of J2 perturbation on relative motion. The simulation results of rendezvous near reference orbit with different eccentricities show that the guidance algorithm is simple, feasible and can be used in remote rendezvous near circle and arbitrary elliptical reference orbit.
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    Guidance Law for Lunar Pinpoint Soft LandingBased on Lyapunov Stability Theory
    LIANG Dong, LIU Liang-Dong, HE Ying-Zi
    2011, 31 (2):  25-31.  doi: 10.3780/j.issn.1000-758X.2011.02.004
    Abstract ( 2833 )   PDF (321KB) ( 1880 )   Save
    To achieve the pinpoint soft landing on a target landing site of the lunar surface, a globally exponentially stable guidance method for lunar pinpoint soft landing was studied by the 3-D spherical nonlinear orbit dynamics model.Based on Lyapunov direct method, a pinpoint guidance law tracking convergent sliding mode was designed. It was theoretically proved that the guidance law was globally exponentially stable by using Lyapunov stability theory. The numerical simulation results show that this guidance method can meet the need of lunar pinpoint soft landing.
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    Review of Deployabletruss Masts for Space Application
    LIU Zhi-Quan, LI Biao, CHENG Gang
    2011, 31 (2):  32-38.  doi: 10.3780/j.issn.1000-758X.2011.02.005
    Abstract ( 5500 )   PDF (512KB) ( 2948 )   Save
    Deployabletruss masts for space application are wildly used in the scope of achieving large size, high stiffness spacecraft. The configuration, mechanism and development of several typical space deployable-truss masts were discussed. The characteristics were compared among these diffenent deployable-truss masts. The trends of the deployable-truss masts were presented. The result show that the ADAM type articulated truss, adaptive to the development of large spacecraft, is the main  trend of space development-truss masts. The key technologies of the ADAM type articulated truss for engineering application were analysed.
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    A New Method for Testing Linear Performance ofHelium Mass Spectrometer Leaker Detector
    WANG Yong, SUN Li-Chen, YAN Rong-Xin, SUN Li-Zhi-
    2011, 31 (2):  39-42.  doi: 10.3780/j.issn.1000-758X.2011.02.006
    Abstract ( 2472 )   PDF (235KB) ( 1959 )   Save
    Based on the characteristic that pumping speed of the mechanical pump was constant within a certain pressure range, a new method for testing the linear performance of the leak detector was proposed. Meanwhile, its rationality was also proved through tests. The gas flow in the leak detector was changed by adjusting the inlet pressure of the leak detector. When the helium concentration in mixed gas was constant, the helium gas flow in the leak detector was also changed. So the output of the leak detector was changed. By changing the relationship between the inlet pressure and the output of the leak detector, the linear performance of the leak detector was obtained. The results show that this method is simple, convenient and inexpensive.
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    Effect of Thruster Configuration on Fuel Consumption
    YUE Xiao-Kui, DUAN Chen-Lu
    2011, 31 (2):  43-46.  doi: 10.3780/j.issn.1000-758X.2011.02.007
    Abstract ( 2684 )   PDF (232KB) ( 1918 )   Save
    The control precision as well as the propellant consumption is directly affected by the amount and configuration of the thrusters. The thrust allocation scheme of a spacecraft was analyzed. Based on the geometric dilution of precision (GDOP) used in satellite navigation system positioning theory, the concept of thruster fuel consume factor (FCF) was proposed to express the ratio between the expect control and the fuel consumption caused by the thrusters. The matrix theoretical analysis shows that FCF decreases as the amount of the thruster increasing.
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    Spacecraft Thermal Control Technology Based onVariable Frequency Pump
    NING Xian-Wen, ZHANG Jia-Xun
    2011, 31 (2):  47-52.  doi: 10.3780/j.issn.1000-758X.2011.02.008
    Abstract ( 2854 )   PDF (327KB) ( 1925 )   Save
    The traditional temperature control mode using temperature sensing valve has three deficiencies with the reliability, dynamic behavior, pump operational efficiency. In order to solve these problems, a new thermal control technology based on variable frequency pump was put forward for a fluid loop prototype model. The temperature control performance of the thermal control technology based on variable frequency pump was tested. During all transients, the controlled temperature was within the range of ±0.3℃ around the setpoint, with a maximum admissible variation range of ±0.5℃. Thermal control strategy based on variable frequency pump has effective performance.
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    Numerical Analysis of Thermal Induced Vibration for Deployable Antenna
    LIU Jin, ZHU Min-Bo, CAO Gang
    2011, 31 (2):  53-57.  doi: 10.3780/j.issn.1000-758X.2011.02.009
    Abstract ( 2906 )   PDF (280KB) ( 1814 )   Save
    Thermal induced vibration of a deployable antenna was analyzed by the non-coupling dynamics and finite element method. Thermal dynamic forces was simulated by a half sine wave thermal shock. Typical model node displacement and stress, as well as root mean square of antenna induced by thermal dynamic forces were discussed. The results show that thermal induced vibration of antenna occurs when thermal dynamic forces greatly change. Meanwhile, the dynamic response of thermal induced vibration is significantly greater than that of the static response.
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    Error Analysis and Moving Target Position for Spaceborne SAR-DPCA with Three-channel
    XIA Meng, YANG Xiao-Niu
    2011, 31 (2):  58-63.  doi: 10.3780/j.issn.1000-758X.2011.02.010
    Abstract ( 2690 )   PDF (372KB) ( 2491 )   Save
    For residual clutter caused by system errors and motion errors in spaceborne SAR-GMTI with three channel when using displaced phase center antenna(DPCA) technology to suppress clutter, a novel method of detection and position for moving target was presented based on error compensation. Aiming at elimination of residual clutter, errors were analyzed in detail and corresponding compensation functions were derived. After compensation, DPCA and interferometric processing were applied to cultter suppression and moving target position.
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    Analysis of H2-Ni Battery Temperature Oscillation Mechanism for GEO Satellites
    LIU Bai-Lin, ZHOU Zuo-Xin
    2011, 31 (2):  64-71.  doi: 10.3780/j.issn.1000-758X.2011.02.011
    Abstract ( 2858 )   PDF (489KB) ( 1992 )   Save
    Based on the layout of the GEO communications satellites bus, the thermal math model (TMM) of south satellite battery cabin was presented to analyze the mathematical mechanism that influences battery temperature on orbit. It is shown that daily change of orbit heat flux will obviously influences the temperatures of west board, +Y panel of Earth deck and +Y panel of anti-Earth deck, and further influences the temperature of service module (SM) structure board through radiation, which induces the battery temperate variation through SM board conduction. This is the key reason of battery temperature variation.
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    Scheduling for Image Satellite Oriented Ocean Survey
    JING Fei, WANG Jun, LI Jun, JING Ning
    2011, 31 (2):  72-78.  doi: 10.3780/j.issn.1000-758X.2011.02.012
    Abstract ( 2645 )   PDF (438KB) ( 1988 )   Save
    Image satellite oriented ocean survey (ISOS) is a type of earth observation satellites(EOSs) in high orbit. The scheduling of EOS is a complex combinatorial optimization. A mathematical model with multiform data transmission mode coexistence was proposed by analyzing the constraints and characteristics of ISOS. A scheduling algorithm for ISOS based on the maximal ratio of gain and loss was presented. The experimental results show that the proposed model and algorithm are effective in solving the scheduling problem of ISOS.
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    Low Bit-rate Image Compression Algorithm Based on CCSDS
    GAO Yu-E, SU Jian
    2011, 31 (2):  79-83.  doi: 10.3780/j.issn.1000-758X.2011.02.013
    Abstract ( 2716 )   PDF (274KB) ( 2091 )   Save
    In order to improve the compression efficiency of the image data compression algorithmadopted by consulative committee for space data system (CCSDS), a two dimensional prediction model was proposed. By utilizing the spatial correlation of pixels existing in the image to improve and optimize the prediction of direct current (DC) coefficients and the entropy coding, the compression performance of DC coefficients as well as enhance the ability for error resiliency could be improved. Experimental results show that the algorithm can obtain better quality of image encoding at low bitrate image and improve (S/N)P by 0.13~0.3dB compared with the original algorithm in CCSDS. Moreover, the proposed algorithm significantly meet the need of the low bit rate transmission of the onboard image compression data.
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