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    Design and Application of Particle Filtering Algorithm Based on URTS Smoothing Proposal Distribution Function
    LI Bao-Li, GONG Yi-Song, GUI Qing-Ming
    null    2011, 31 (3): 14-19.   DOI: 10.3780/j.issn.1000-758X.2011.03.003
    Abstract10740)      PDF(pc) (330KB)(1957)      
    To improve the state estimate performance of the particle filtering with the Unscented Kalman filtering proposal distribution function, the Unscented Kalman filtering and the Rauch-Tung-Striebel (RTS) fixed interval smoothing algorithm were integrated, and a new kind of proposal distribution function named as Unscented RTS smoothing proposal distribution function was designed. The Unscented RTS smoothing distribution implements the Unscented Kalman filtering, and then carries out the RTS fixedinterval smoothing to produce a prediction sample. The accuracy of prediction particles is greatly improved by the new proposal distribution function, and the state estimation accuracy of the corresponding particle filtering method (PF-URTS) is also improved. The applications of the new particle filtering algorithm to the GPS/DR integrated navigation system will prove the feasibility and validity of  the proposed  method.
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    UDUT FACTORIZATION FILTER AND ITS APPLICATION
    Chen Zngui (Beijing Institute of Control Engineering)
    null   
    Abstract8986)           
    In this report the UDUT factorization filter algorithm is pre-sented.The whole filter formulae,including time updating and measurementupdating,have been derived by using a simple method,which is easy tounderstand by engineer.A standard and universal UDU~T factorization filtersubroutine has been writeen using FORTRAN-77.The algorithm has highnumerical stability.As a bridge between the UDU~T factorization filter theoryand engineering application,the standrad and universal subroutine has goodperformance,application flexibility and can be applied to other scientificfields.
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    VFAS ADAPTIVE SOFTWARE SYSTEM ON VIEW FACTORS
    Fu Zhenxuan (Beijing Institute of Information and Control) Li Xilun Yao Weidong (Beijing Institute of Spacecraft System Engineering)
    null   
    Abstract5923)           
    Based on VF01 and VF02,VFAS system has made a great progress in reducing the user's man-hour and improving the accuracy of the calculation results.The calculation of viewfactor among different surfa- ces now may be changed into that among any different nodes,and the shadowing between nodes can be decided automatically by the system.
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    In orbit Estimation of Satellite inertial matrix using STLS
    LIN Jia-Wei, WANG Ping
    null    2010, 30 (6): 31-38.  
    Abstract5712)      PDF(pc) (384KB)(3106)      
    Dynamics equations of inertial matrix estimation were deduced. The structured total least norm (STLN) algorithm was used to estimate the parameters. Theoretical analysis shows that the STLS solution is maximum likelihood estimate when the sensor noise is Gaussian. This method has two advantages over existing methods: sensor noise is considered and the consistency of the estimate is proved.
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    Review of Deployabletruss Masts for Space Application
    LIU Zhi-Quan, LI Biao, CHENG Gang
    null    2011, 31 (2): 32-38.   DOI: 10.3780/j.issn.1000-758X.2011.02.005
    Abstract5610)      PDF(pc) (512KB)(3054)      
    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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    Orbit Design for Mars Exploration by the Accurate Dynamic Model
    CHEN Yang, ZHAO Guo-Qiang, BAOYin He-Xi, LI Jun-Feng
    null    2011, 31 (1): 8-15.   DOI: 10.3780/j.issn.1000-758X.2011.01.002
    Abstract5342)      PDF(pc) (479KB)(2956)      
    The precision orbit design for Mars exploration by the accurate dynamic model was studied. The launch window and trans-Mars orbit was determined through the partical swarm optimization (PSO) algorithm within the heliocentric two-body restriction. The patched conics method was introduced to design the earth-centred parking orbit and departure hyperbolic orbit. The solution of two-body Lambert problem was input as initial value for precision orbit design, and the preliminary orbit was corrected with the restrictions of the Mars B-plane parameters and flight time by the accurate dynamic model. Finally the designed orbit was simulated with the STK softwares.
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    Cited: Baidu(13)
    Nonlinear Feed Forward Control on Attitude andOrbital Coupling Model  for Spacecraft
    TIE Yu-Jia, YUE Xiao-Kui, CAO Jing
    null    2010, 30 (6): 11-16.  
    Abstract5238)      PDF(pc) (322KB)(2385)      
    Precise relative orbit and attitude model play a significant role in the spacecrafts formation flying, rendezvous and docking. Nevertheless, the independent relative orbital model can't meet the high precision requirements. Based on the nonlinear relative motion dynamics equations and attitude kinematics equations described by modified Redrigues parameters (MRPs), a relative dynamic model of 6 DOF was developed. The accuracy of the model is  guaranteed with couplings and nonlinear terms′supporting. Nonlinear feed forward control law was designed for the coupled nonlinear dynamic model, whose close loop system was proved to be global asymptotic stable by Lyapunov direct method. The numerical simulations results verify the effectiveness of the model and control law.
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    Target Spacecraft Phasing Strategy in Orbital Rendezvous
    ZHANG Jin, HUANG Hai-Bing, WANG Wei, TANG Yi
    null    2011, 31 (1): 33-41.   DOI: 10.3780/j.issn.1000-758X.2011.01.005
    Abstract4951)      PDF(pc) (447KB)(2602)      
    To make preparations for the rendezvous and docking, the target phasing maneuver mission is a non-fixed time rendezvous problem. According to the basic phasing principle, the phase influences by atmosphere drag, drift of right ascension of ascending node and orbital errors were analyzed and used to improve the approximate formulae, which estimated the effect of impulse on the phase angle. With the combination of the approximate formulae and the numerical integration, the target phasing strategy was improved in three aspects: the calculation of maneuver data for the perturbed trajectory, the selection of the phasing-direction and the selection of the maneuver revolution number. The simulation results show that the proposed target phasing strategy can obtain the maneuver data for the perturbed trajectory and can meet the terminal precision requirements. Compared with the phasing-direction selection method, with which only the terminal phase angle deviation is considered, the proposed strategy can reduce the fuel consumption.
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    Applications and Construction of the Structured LDPC Codes in Satellite Navigation System
    JIANG Ming, HE Shan-Bao, DOU Jin-Fang, ZHAO Chun-Ming, WANG Chen
    null    2010, 30 (6): 64-71.  
    Abstract4850)      PDF(pc) (533KB)(2449)      
    The structured low density parity check (LDPC) codes can be described by the base-matrices and lifting factors, which have low encoding/decoding complexity and good coding performance. Compared to the irregular LDPC codes specified in IS-GPS-800, the structured LDPC codes also can be encoded with linear complexity, where the parity bits are connected with dual-diagonal and “a-0-a” pattern. Moreover, it is very convenience for the structured LDPC codes to support the adaptive transmissions with various lengths using different lifting factors and pruning techniques, where the puncturing and shortening patterns can be easily optimized by PEXIT. Based on the construction method considering cycle conditions and ACE spectrums, a simple coding scheme using only one base-matrix was proposed which can support two different lifting factors and achieve various transmission lengths by puncturing and shortening. The simulation result show that the structured LDPC codes with optimized puncturing/shortening pattern achieve considerable performance gain over the irregular LDPC codes in IS-GPS-800.
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    Transfer Matrix for Relative Dynamics in Elliptic Orbit
    YUE Xiao-Kui, YUAN Yun-Xia
    null    2011, 31 (1): 42-47.   DOI: 10.3780/j.issn.1000-758X.2011.01.006
    Abstract4757)      PDF(pc) (283KB)(3067)      
    Based on Lawden equation, a new form of state transfer matrixes was presented. The state transfer matrix was derived in terms of position-velocity in solid space, and transformed from angle domain to time domain, so the state transfer matrix denoting true position and velocity was obtained. Arbitrary forms can be obtained by primary transformation. The numerical simulations show this state transfer matrix is effective and feasible for theory and project applications. It can be used for solid orbit rendezvous, orbit correction, formation configuration design and control for elliptic orbits with arbitrary eccentricity.
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    THE ONE OF THERMAL PHYSICAL PROPERTIES OF CARBON FIBRE/EPOXY—RESIN COMPOSITES—THERMAL CONDUCTIVITY
    Zhang Jianke (Lanzhou Physics Institute)
    null   
    Abstract4714)           
    The relations between thermal conductivity of carbon fibre/epoxy-resin composites and various volume concentrations of fibre V_f and temperature have been discussed. The thermal conduction mechanism of Carbon fibre/epoxyresin is researched and a lot of results are given in this paper.
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    Semi-empirical Method for Force Specification in Force Limited Vibration Test
    LI Zheng-Ju, MA Xing-Rui, HAN Zeng-Yao
    null    2011, 31 (1): 1-7.   DOI: 10.3780/j.issn.1000-758X.2011.01.001
    Abstract4693)      PDF(pc) (372KB)(2754)      
    The force limited vibration test can alleviate the over testing phenomenon generated by the resonant frequency in the acceleration-controlled vibration test. Force specification estimation is a prerequisite for the force limited vibration test. The principle of force limited vibration test was introduced. And the calculation method for semi-empirical coefficient was derived by the two degree of freedom system. Furthermore, the force specification of some spacecraft payload was caculated in the random vibration test. The results show that this method is reasonable to estimate the force specification.
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    Guidance for Dynamic Obstacle Avoidance of Autonomous Rendezvous and Docking with Non-Cooperative Target
    SONG Shen-Min, ZHANG Da-Wei, PEI Run
    null    2010, 30 (6): 39-48.  
    Abstract4678)      PDF(pc) (558KB)(2692)      
    Firstly, the relative motion state equations were described in line of sight coordinate frame. And the artificial potential function guidance was used for autonomous rendezvous and docking  with a non-cooperative target spacecraft and dynamic obstacle avoidance missions. Then, mission of autonomous rendezvous and docking with the non-cooperative target was accomplished and dynamic obstacle avoidance was studied by potential function guidance. Secondly, the stability of the method was analyzed and proved by Lyapunov theory, and the effects of two different dynamic obstacle avoidances were studied and discussed. Meanwhile, the capability of potential function guidance was analyzed. Finally, the numerical simulation results based on a precise mathematic model demonstrate the validity and effectiveness of the proposed guidance method.
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    Rotating Formation Flying for Tethered Micro-satellites
    CHEN Zhi-Ming, LIU Hai-Ying, WANG Hui-Nan, FENG Cheng-Tao
    null    2011, 31 (1): 76-83.   DOI: 10.3780/j.issn.1000-758X.2011.01.011
    Abstract4676)      PDF(pc) (451KB)(2491)      
    A tethered control method was studied in order to solve three satellites formation  flying problem. Based on the equilibrium analysis of spinning rigid body satellite, the Thomson and Likins-Pringle equilibrium modeling of three satellites formation flying using tethers were established. The equilibrium conditions were obtained through equilibrium analysis of formation system, and then three control methods were presented to solve disequilibrium problem of Likins-Pringle equilibrium system. Simulation  results demonstrate that the Thomson equilibrium system will be in steady-spin motion with specific conditions, and Likins-Pringle equilibrium system will operate steadily using spring system and tethers added with thrusters control methods under specific conditions.
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    Parallel Imaging of MPI and Pthread Mixed Programming Based on Cluster
    TIAN Lei, FAN Shi-Ming
    null    2010, 30 (5): 31-38.  
    Abstract4629)      PDF(pc) (358KB)(2513)      
    The mixed programming for Nonlinear Chirp Scaling (NCS) algorithm was designed according to the requirements of space borne Synthetic Aperture Radar (SAR) real time and near real time imaging. The two level pipelined parallel imaging of multiprocess and multithread with Message Passing Interface (MPI) and Pthread was researched and implemented on SMP cluster. Through the experiments on HP cluster, it is proved that the mixed program imaging algorithm can not only adapt to the instance that the time of one block of original echo data transferred from the front system is more than or equal to eight seconds, but also the instance that a great number of  original  echo data has been already accumulated.
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    THE RESEARCH ON CROSSING DIPOLES CIRCULAR POLARIZATION ANTENNAS
    Liu Jianxin(Beijing University of post and Telecommunication, Beijing 100088)Yan ZhongWen(Beijing Institute of Spacecraft System Engineering, Beijing 100086)
    null   
    Abstract4567)           
    y the Hallen equation's solution, a method of forming crossing dipoles circular polarization antennas from choosing the length of dipoles is given in this paper.The equation is solved by moment method. The computed and measured circular polarization antennas' patterns are also given. Because of the simple and reliable structure, this sort of antennas can be used widely in spacecraft.
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    EXTRACTING INTRINSIC IMAGES IN COLOR IMAGE
    Huang Yuming (Beijing Institute of Control Engineerig) Xu Guangyou (Qing Hua University) Ye Peijian (CAST)
    null   
    Abstract4469)           
    The position and the color of a light source affect the image ofan object,and ideal results can't be obtained by usual segmentation algorithmdue to the appearence of highlights.The Dichromatic Reflection Model is usedto divide a color image into two intrinsic images——matte image and highl-ight image.The matte image is the original image with the highlights remo-ved,reflecting the invariance of the object and being not affected by theenvironmental factors(such as the position and the color of the light sour-ce);but the highlight image is just an image of highlights,reflecting theenvironmental factors,and providing information for shape from gloss.The color image in this paper refers to that of a monochrome object gene-rated by color CCD camera under monochrome light(not the light with singlewavelength).
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    Modulation Transfer Function Compensation Technology of Optical Remote Sensing Imaging System
    Zeng Yong1 Chen Shiping2 Yu Jin1 (1 China Center for Resources Satellite Data and Application,Beijing 100094) (2 China Academy of Space Technology,Beijing 100081)
    null   
    Abstract4388)           
    Modulation transfer function compensation (MTFC) is very important for optical remote sensing imaging system to promote image quality and optimize the imaging system modulation transfer function (MTF). Based on inverse filtering and Wiener filtering,the MTFC technology was studied and improved according to CBERS imaging system characteristics. The optimal design of MTFC was done from MTFC curve shape as follows:the middle frequency MTF was enhanced remarkably,and the high frequency part was enhanced moderately. It not only improved the image definition,but also controlled the noise involved. Compromise has been found between the image definition and noise for this technology. CBERS-02B HR imaging system is taken as an example,the result shows that MTFC can improve the image quality obviously,and at the same time,it increases some noises. Several suggestions are given to the applicability of MTFC finally.
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    Cited: Baidu(3)
    Reliability Verification Test Methods of a Connecting/Separating Mechanism for Manned Spacecraft
    LIU Zhi-Quan, SUN Guo-Peng, GONG Ying
    null    2011, 31 (1): 56-61.   DOI: 10.3780/j.issn.1000-758X.2011.01.008
    Abstract4273)      PDF(pc) (406KB)(2404)      
    The functions, principles and failure modes of a connecting/separating mechanism for manned spacecraft were introduced. Reliability characteristic parameters of the mechanism were given. The reliability verification test method of the mechanism was put forward, including test method choosing, test state determination, test program, failure criterion and  reliability  assessment  method. An application example of the method was shown. By these reliability  verification  test methods, the reliability of the connecting/separating mechanism for manned spacecraft could be verified.
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    Thermal-structural Modeling and Simulation for Scan Mirror on Imager in Solar Radiation
    YOU Si-Liang, CHEN Gui-Lin, WANG Gan-Quan
    null    2011, 31 (1): 62-69.   DOI: 10.3780/j.issn.1000-758X.2011.01.009
    Abstract4162)      PDF(pc) (646KB)(2484)      
    The solar-radiation disturbance exists in the optical payloads onboard the three-axis stabilized satellite platform. It leads to thermal distortion, which obviously affects the imaging quality of optical system. The approximate modeling technique of complex external heat flux was applied, as well as the multi-software-coupled finite element simulation. The thermal effect of the imager′s scan mirror caused by solar radiation was researched, and compared under different thermal design conditions on the FY-4 imager. The optimal scheme of the thermal design of the scan mirror was obtained. The result shows that the thermal distortion is closely related to the thermal coating on the side and the back of the scan mirror. It is difficult to  resolve  the conflict  between the temperature fluctuation and the thermal distortion if only using the thermal design method. It is necessary to improve the material of the scan mirror or adjust the optical-mechanical structure.
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