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25 April 2003, Volume 23 Issue 02 Previous Issue    Next Issue

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Lagrange's Equations in Quasicoordinates for Dynamics Modeling of Flexible Spacecraft Miao Bingqi * Qu Guangji ** Xia Suiqin * Cheng Daosheng ** ( *College of Mechanical and Electrical Engineering, Zhejiang University of Technology,Hangzhou 310014) ( ** Chinese Academy of Space Technology, Beijing 100086)$$$$ 2003, 23 (02):  .  Abstract ( 1933 )   Save Lagrange's equations in quasicoordinates are usually used for dynamics modeling of spacecraft. This paper provides a formulation of Lagrange's equations in quasicoordinates for dynamics modeling of multi body flexible spacecraft based on the Hamilton's principle. From the derived equations the dynamic equation of flexible spacecraft with central body and flexible appendages is created. Related Articles | Metrics

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Matrix Reduction Method for Updating Dynamic Model Zhu Anwen Qu Guangji Gao Yaonan (Beijing Institute of Spacecraft System Engineering, Beijing 100086)$$$$ 2003, 23 (02):  .  Abstract ( 1990 )   Save When the spacecraft structural dynamic model is updated using test data, the freedom of FEM can be matched with test freedom by means of reduction method. A new method of iterative matrix reduction based on Guyan reduction and IRS reduction is brought forward, which has low converge speed but with high analysis accuracy. Related Articles | Metrics

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Differential Smoothing of Fused Range Rate He Mingke Zhu Jubo (National University of Defense Technology, Changsha 410073) Ma Shunnan Liu Qiuhui (Naval Base of Test, Dalian 116023)$$$$ 2003, 23 (02):  .  Abstract ( 1959 )   Save In target tracking system, some radar can provide the measurements such as slant range, elevation, azimuth and range rate. Discussed in this paper is a polynomial least squares differential smooth algorithm used to determine velocity of targets by these measurement. The algorithm in this paper fuses state information and range rate information. And the simulation results indicate that this algorithm can increase the estimate accuracy of velocity. Related Articles | Metrics

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Research of Multi-Agent Based Satellite Fault Diagnosis and Fusion Technology Fan Xianfeng Jiang Xingwei (Harbin Institute of Technology, Harbin 150001)$$$$ 2003, 23 (02):  .  Abstract ( 1547 )   Save In order to improve the accuracy of Multi Agent based fault diagnosis system for satellite and to make use of diagnosis information captured by every diagnosis method, technology of data fusion is introduced into Multi Agent diagnosis based on the analysis of fault diagnosis theory . Weights are introduced into fusion of diagnosis result according to the feature of satellite fault diagnosis. The improved Dempster Shafer evidential theory arithmetic and the method of weights calculating are given. At last, validity of the method is proved by an example given in this paper. Related Articles | Metrics

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Study of Low α_ s Organic Thermal Control Coatings and Their Protection for Space Materials Zhang Lei * Yan Chuanwei * Sun Gang ** Tong Jingyu ** Li Jinhong ** Cao Chunan * (* State Key Lab for Corrosion and Protection, Institute of Metal Research, The Chinese Academy of Sciences, Shenyang 110016) (** Beijing Institute of Spacecraft Environment Engineering, Beijing 100029)$$$$ 2003, 23 (02):  .  Abstract ( 1586 )   Save The white control coating with low ratio of solar absorptance to emittance is successfully prepared Three low sunlight absorption siloxane thermal control coatings are developed and the factors( resin type, filler type, ratio of resin to pigment ect) which influence the protection are also investigated Surface protection and transfor ratio of thermal control coating are analyzed after exposure to ground state fast atomic oxygen(AO)radiation environment using LAMBDA 9 spectroradimeter and scanning electron microscope The result shows that siloxane thermal control coatings has excellent protection against anti AO effects and good stability for space environment Specialy, 9 5 siloxane thermal control coating has the lowest α s , and the most stable Related Articles | Metrics

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Concept of Spacecraft Sparse Formation-Flying and Its Design Method Sun Lan Xu Bin Zhang Heng (Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080)$$$$ 2003, 23 (02):  .  Abstract ( 1604 )   Save A new concept of spacecraft sparse formation flying and its design method are presented in this paper. Differences between the new concept and the widely accepted spacecraft compact formation flying are explained, and possible application prospects of sparse formation flying are described. A new formula that is more widely applicable than Hill's solution is proposed for the design of sparse flying formations, and several sparse formations are derived. In the case that distances between formation spacecrafts are very closed, the new formula become naturally the same as Hill's solution. Advantages of the new formula are illustrated clearly by calculating one simple example. Related Articles | Metrics

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Research of Multi-Agent Based Satellite Fault Diagnosis and Fusion Technology Fan Xianfeng Jiang Xingwei (Harbin Institute of Technology, Harbin 150001)$$$$ 2003, 23 (02):  .  Abstract ( 1847 )   Save In order to improve the accuracy of Multi Agent based fault diagnosis system for satellite and to make use of diagnosis information captured by every diagnosis method, technology of data fusion is introduced into Multi Agent diagnosis based on the analysis of fault diagnosis theory . Weights are introduced into fusion of diagnosis result according to the feature of satellite fault diagnosis. The improved Dempster Shafer evidential theory arithmetic and the method of weights calculating are given. At last, validity of the method is proved by an example given in this paper. Related Articles | Metrics

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A Multi-Rigid-body Model of Parachute Deployment Zhang Qingbin Cheng Wenke Peng Yong Qin Zizeng (College of Aerospace and Material Engineering, National University of Defense Technology, Changsha 410073)$$$$ 2003, 23 (02):  .  Abstract ( 1940 )   Save A numerical simulation of parachute deployment is examined by multi rigid body model. The parachute system is regarded as a chain multi rigid body. An order n recursion algorithm is constructed to resolve constrain between ropes. The model can be used to study the "Line Sail" of parachute deployment. Related Articles | Metrics

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The Study on Double-Star Position/SINS Integration Navigation System Lin Xueyuan Liu Jianye Wang Shuhua (Navigation Research Center, Nanjing University of Aeronautics and Astronautics, Nanjing 210016)$$$$ 2003, 23 (02):  .  Abstract ( 1683 )   Save Double star position system is one kind of regional position system build up. The position principle of Double star position system is introduced, and its shortcoming that is the bad real time of position is explained. For this fact one scheme that the output velocities of SINS after revised by the Kalman filter modify the output level positions of Double star navigation system is put forward, then the Double star position system is integrated with the inertial system, and the state and measurement equations are build up. The simulation results demonstrate this method is feasible, and has an important theoretic value for the practical use of the Double star navigation system. Related Articles | Metrics

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Configuration Maintenance and Initialization Satellite Formations Han Chao Tan Tian Yang Yu (Beijing University of Aeronautics and Astronautics, Beijing 100083)$$$$ 2003, 23 (02):  .  Abstract ( 2065 )   Save This paper deduces the orbit maneuver equations for relative motion control of satellite formations based on the relative orbit elements. It proposes orbit maneuver control methods for relative orbital motion control of satellite formations, including the maneuver control both in and out of the orbit plane, based on orbit parameters of relative motion controlled by pulses in different directions. The configuration initialization of satellite formations is carried out based on orbit maneuver control of relative elements. This orbit initialization can be considered as a special kind of orbit maneuver control. This procedure in easily realized for initialization of satellite formations . Related Articles | Metrics

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The Study of the Effect of O-Ring Exposure to Atomic Oxygen and Ultraviolet Shao Xinjie (Ordnance Engineering College, Shi Jiazhuang 050003) Zhang Jianbin (Beijing University of Aeronautics & Astronautics, Beijing 100083) Wang Guangzhen (Tsinghua University, Beijing 100084)$$$$ 2003, 23 (02):  .  Abstract ( 1560 )   Save Experiments are conducted with the ground analog equipments to investigate the effect of atomic oxygen and ultraviolet on silicone rubber O rings. By measuring the pressure between two O rings, leakage rates before and after exposure to atomic oxygen or ultraviolet are compared . In addition,the surface characteristics of O ring are analyzed by scanning electron microscope . All experiments prove that the surface characteristics and leakage rate of an O ring are affected seriously when it is exposed to atomic oxygen and ultraviolet. Related Articles | Metrics

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Design on GPS/INS Integrated Navigation System Based on Free Software Kuang Qihe Liu Jianye (College of Automation Engineering, NUAA, Nanjing 210016)$$$$ 2003, 23 (02):  .  Abstract ( 1647 )   Save Free software has brought a novel design mode to navigation system. The real time core may be tailored to navigation system. This paper presents GPS/INS integratd navigation system design based on free software. A practical of GPS/INS integrated navigation system based on uC/OS free soft ware is presented. The simulation has verified the system's good performance. Related Articles | Metrics