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25 February 2006, Volume 26 Issue 01 Previous Issue    Next Issue

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Formation Control for Spacecraft in Eccentric Orbits Yu Ping Zhang Honghua(Beijing Institute of Control Engineering,Beijing 100080) 2006, 26 (01):  1-8.  Abstract ( 1743 )   Save Some formation modes of spacecraft formation flying in eccentric orbits are derived.The formation modes in eccentric orbits are more than the formation modes in circular orbits.Based on the Tschauner-Hempel equation the formation control algorithm for spacecraft in eccentric orbits is put forward.The control acceleration is on the track of orbit and is fixed in this control(algorithm).The control schedule is optimized in order to economize fuel.Furthermore,numerical(examples) and simulation results are also given to verify the effectiveness of the algorithms proposed above. Related Articles | Metrics

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The Overall Design Method of Spacecraft Rendezvous Zhu Renzhang~1 Tang Yi~2 Li Yili~2 Lin Yan~1(1 Beijing University of Aeronautics and Astronautics,Beijing 100083)(2 China Academy of Space Technology,Beijing 100094) 2006, 26 (01):  9-16.  Abstract ( 1674 )   Save The overall design method of spacecraft rendezvous is investigated,where the chaser is semi-autonomic.The flight time and the initial phase difference can be determined,if the(inclination) and the orbital period of the target vehicle and the injection and docking position of the chaser vehicle are known.The orbit maneuver and the trajectory of chaser are designed,in order to regulate the flight time and phase difference,and complete the rendezvous mission. Related Articles | Metrics

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Detection of Systematic Error Based on Integral Matched Filter Duan Xiaojun Zhu Jubo Wang Guangxin(National University of Defense Technology,Changsha 410073) 2006, 26 (01):  17-21+58.  Abstract ( 1827 )   Save As far as the target tracking system is concerned,if the measurement units applied in data fusion,such as location or velocity,have systematic error,the Least-square differential smooth method can be used to filter and detect the systematic error.Since the processing precision of differential smooth method is low,a method of integral matched filter is proposed.The(mathematical) deduction testifies that this method can obtain more precise systematic error(estimation) than the differential smooth method.And the simulation result also verifies this(conclusion). Related Articles | Metrics

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An Improved Adams-Cowell Algorithm Fu Zhaoping Li Hong(Hua Zhong University of Science and Technology,Wuhan 430074) 2006, 26 (01):  22-26.  Abstract ( 2595 )   Save A more precise algorithm(WA-C) in calculating orbital equation is given,on the base of classical Adams-Cowell algorithm.WA-C is revised by using extrapolation technology to(improve) precision.An example is tested through A-C,KSG,ACm and WA-C algorithm,and(comparison) is given.The test result shows that WA-C algorithm is more efficient to improve(precision) in orbital equation calculation then other methods. Related Articles | Metrics

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Autonomous Navigation of Low-Earth-Orbit Satellites Using Magnetic Measurements by Unscented Kalman Filter Gao Changsheng Jing Wuxing Zhang Yan Huang Xiangyu(Harbin Institute of Technology,Harbin 150001) 2006, 26 (01):  27-32.  Abstract ( 1940 )   Save Autonomous navigation does not need any information from the land station,so it can satisfy some specific requirements.In order to describe the distribution of the geomagnetic field better,the high-accuracy dynamic model of orbit and the 10×10-order model of the geomagnetic field are established.Taking the vector and the magnitude of the geomagnetic field as the observed variable respectively,the autonomous navigation is realized by the Unscented Kalman Filter.(Suppose) that the sampling period is 10s,and the measurement noise of the magnetometer is 100nT,the results of the simulation show that the satellite navigation error is 1km、0.9km、0.3km.When the observed variable is the geomagnetic vector,otherwise it is 1.6km、1.3km、0.5km. Related Articles | Metrics

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Review of the Development of Soft-landing Mechanisms for Lunar Explorations Liu Zhiquan Huang Chuanping(China Academy of Space Technology,Beijing 100094) 2006, 26 (01):  33-39.  Abstract ( 1719 )   Save Soft-landing is the key technique for lunar exploration.The development of soft-landing mechanisms for lunar explorations is reviewde,and the structures,principles and(characteristics) of soft-landing mechanisms are analysed.Analyses of the characteristics of different deployment mechanisms and snubbers on soft-landing mechanisms are carried out.The(development) tendencies of the soft-landing mechanisms for lunar probe are predicted. Related Articles | Metrics

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Security Architecture of Space Internet Wang Jian Zhang Quan Tang Chaojing(School of Electronic Science and Engineering,National University of Defense Technology,Changsha 410073) 2006, 26 (01):  40-47.  Abstract ( 1639 )   Save According to the principle and method of designing security architecture of(information) system,incorporated the characters of space communication,the security architecture model of space internet is promoted by analyzingsecurity threats,security requirements,security policies and security mechanisms in space internet. Related Articles | Metrics

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Relatively Locating a Space Target Using Angle-only Measurements Liu Yuan Xie Jingwen Wu Zhengrong(Beijing Institute of Tracking and Telecommunication Technology,Beijing 100094) 2006, 26 (01):  48-52+71.  Abstract ( 1715 )   Save The problem of locating a space target relatively using angle-only measurements is(investigated).These measurements are collected from multi-sensors synchronously.A differential-self-calibration method with extended Kalman filter(EKF) is proposed.The effect of the method is demonstrated by simulation,and the result of simulation shows that the good real-time(characteristic) with accurate results. Related Articles | Metrics

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The Attitude Integrated Algorithm in Complete Integrated GPS/SINS Navigation System Du Yaling Liu Jianye Xiong Zhi(Navigation Research Center,Nanjing University of Aeronautics & Astronautics,Nanjing 210016)Jiang Yong(Unmanned Aerial Vehicles Research Department,Nanjing University of Aeronautics & Astronautics,Nanjing 210016) 2006, 26 (01):  53-58.  Abstract ( 1955 )   Save The difference of platform angles error and attitude error are analysed,and the(conversion) matrix is gained.To take the application into account,the observations vector(pretreatment) instead of complicated attitude observation equation is used,to improve the attitude integrated algorithm.Then the system eliminates the math former errors,and realized very easy.The plentiful simulations results show that the improved attitude integrated algorithm can enhance the precision validly, Related Articles | Metrics

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Pattern Character Based Image Compression Method You Yuhu Zhou Xiaokuan(School of Astronautics,Beijing University of Aeronautics and Astronautics,Beijing 100083) 2006, 26 (01):  59-64.  Abstract ( 1660 )   Save Even though the wavelet based image compression algorithms have been well(recognized) recently,the compression results of these algorithms are not well enough for the images with rich textures,since the spatial pattern characters of an image which are important for human vision have not yet been involved in these algorithms directly.A new image compression method based directly on pattern characters of image named PCBC(Pattern Character Based Image(Compression) Method) is introduced.The results of testing on a set of remote sensing images with rich textures show that the PSNR(Power Signal-to-Noise Ratio) of PCBC is higher than that of SPIHT(Set Partitioning in Hierarchical Trees). Related Articles | Metrics

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Space-borne SAR Image Simulation and Its Application in Geo-rectification You Hongjian Ding Chibiao Wu Yirong(Institute of Electronics,Chinese Academy of Sciences,Beijing 100080) 2006, 26 (01):  65-71.  Abstract ( 2297 )   Save The image position of space-borne SAR is calculated based on range-doppler principle and then the scatter coefficientof terrain is simulated according to experientialformula.The(density)of simulated image points in mountain is not symmetricalowing to the difference between the interval of DEM and the resolution of SAR image,and side-look character of SAR.Four DEM corner points are used to interpolate the simulated SAR image.The space-borne SAR is rectified(after) thatthe simulated image is matched with the real SAR image.The method is demonstrated by simulating RADARSAT image and rectifying the real SAR image. Related Articles | Metrics